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Shah DD, Carter P, Shivdasani MN, Fong N, Duan W, Esrafilzadeh D, Poole-Warren LA, Aregueta Robles UA. Deciphering platinum dissolution in neural stimulation electrodes: Electrochemistry or biology? Biomaterials 2024; 309:122575. [PMID: 38677220 DOI: 10.1016/j.biomaterials.2024.122575] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2024] [Revised: 03/28/2024] [Accepted: 04/13/2024] [Indexed: 04/29/2024]
Abstract
Platinum (Pt) is the metal of choice for electrodes in implantable neural prostheses like the cochlear implants, deep brain stimulating devices, and brain-computer interfacing technologies. However, it is well known since the 1970s that Pt dissolution occurs with electrical stimulation. More recent clinical and in vivo studies have shown signs of corrosion in explanted electrode arrays and the presence of Pt-containing particulates in tissue samples. The process of degradation and release of metallic ions and particles can significantly impact on device performance. Moreover, the effects of Pt dissolution products on tissue health and function are still largely unknown. This is due to the highly complex chemistry underlying the dissolution process and the difficulty in decoupling electrical and chemical effects on biological responses. Understanding the mechanisms and effects of Pt dissolution proves challenging as the dissolution process can be influenced by electrical, chemical, physical, and biological factors, all of them highly variable between experimental settings. By evaluating comprehensive findings on Pt dissolution mechanisms reported in the fuel cell field, this review presents a critical analysis of the possible mechanisms that drive Pt dissolution in neural stimulation in vitro and in vivo. Stimulation parameters, such as aggregate charge, charge density, and electrochemical potential can all impact the levels of dissolved Pt. However, chemical factors such as electrolyte types, dissolved gases, and pH can all influence dissolution, confounding the findings of in vitro studies with multiple variables. Biological factors, such as proteins, have been documented to exhibit a mitigating effect on the dissolution process. Other biological factors like cells and fibro-proliferative responses, such as fibrosis and gliosis, impact on electrode properties and are suspected to impact on Pt dissolution. However, the relationship between electrical properties of stimulating electrodes and Pt dissolution remains contentious. Host responses to Pt degradation products are also controversial due to the unknown chemistry of Pt compounds formed and the lack of understanding of Pt distribution in clinical scenarios. The cytotoxicity of Pt produced via electrical stimulation appears similar to Pt-based compounds, including hexachloroplatinates and chemotherapeutic agents like cisplatin. While the levels of Pt produced under clinical and acute stimulation regimes were typically an order of magnitude lower than toxic concentrations observed in vitro, further research is needed to accurately assess the mass balance and type of Pt produced during long-term stimulation and its impact on tissue response. Finally, approaches to mitigating the dissolution process are reviewed. A wide variety of approaches, including stimulation strategies, coating electrode materials, and surface modification techniques to avoid excess charge during stimulation and minimise tissue response, may ultimately support long-term and safe operation of neural stimulating devices.
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Affiliation(s)
- Dhyey Devashish Shah
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia
| | - Paul Carter
- Cochlear Ltd, Macquarie University, NSW, Australia
| | | | - Nicole Fong
- Cochlear Ltd, Macquarie University, NSW, Australia
| | - Wenlu Duan
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia
| | - Dorna Esrafilzadeh
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia
| | - Laura Anne Poole-Warren
- Graduate School of Biomedical Engineering, University of New South Wales, Sydney, Australia; The Tyree Foundation Institute of Health Engineering, University of New South Wales, Sydney, Australia.
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Fenov DM, Salcher R, Kludt E, Lesinski-Schiedat A, Harre J, Lenarz T, Giesemann A, Warnecke A. Long-term experience with biohybrid cochlear implants in human neurosensory restoration. Cochlear Implants Int 2024:1-11. [PMID: 39159131 DOI: 10.1080/14670100.2024.2379124] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/21/2024]
Abstract
OBJECTIVE The implantation of biohybrid electrodes was introduced a few years ago in our clinic. These electrodes coated with autologous mononuclear cells releasing anti-inflammatory and neuroprotective factors are thought to reduce insertion trauma and maintain the vitality of surviving spiral ganglion neurons. The clinical feasibility of this approach has already been demonstrated. In the present retrospective study, the four-year results of the two sides (classical electrode and biohybrid electrode) in the bilaterally implanted patients were compared in order to investigate possible adverse long-term effects. METHODS All patients received a complete audiological diagnosis which also included a speech audiogram and impedance measurement. The measurements were carried out 1 month, 3 months, 6 months, 1 year, 2 years, 3 years and 4 years after implantation. The hearing results were assessed by pure tone audiometry. RESULTS All patients showed satisfactory speech understanding and similar impedances on both sides although they had a long-term deafness before implantation of the side provided with a biohybrid electrode array. The results of speech understanding and impedance measurements were stable for years. Cone beam computed tomography was performed in 4 patients three years after implantation and could rule out cochlear ossification. Other complications were also not registered in any of the patients. CONCLUSION Due to satisfactory outcomes and lack of complications, the biohybrid electrode is considered to be a safe option in cochlear implantation. The simplicity of application of autologous cells as a source of anti-inflammatory and neuroprotective factors via a biohybrid electrode array is a key step for cell-based, regenerative therapies for deafness.
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Affiliation(s)
- Dragana Mitovska Fenov
- Department of Otolaryngology Head and Neck Surgery, Hannover Medical School, Hannover, Germany
| | - Rolf Salcher
- Department of Otolaryngology Head and Neck Surgery, Hannover Medical School, Hannover, Germany
| | - Eugen Kludt
- Department of Otolaryngology Head and Neck Surgery, Hannover Medical School, Hannover, Germany
| | - Anke Lesinski-Schiedat
- Department of Otolaryngology Head and Neck Surgery, Hannover Medical School, Hannover, Germany
| | - Jennifer Harre
- Department of Otolaryngology Head and Neck Surgery, Hannover Medical School, Hannover, Germany
- Cluster of Excellence 'Hearing for All', German Research Foundation, Bonn, Germany
| | - Thomas Lenarz
- Department of Otolaryngology Head and Neck Surgery, Hannover Medical School, Hannover, Germany
- Cluster of Excellence 'Hearing for All', German Research Foundation, Bonn, Germany
| | - Anja Giesemann
- Department for Diagnostic and Interventional Neuroradiology, Hannover Medical School, Hannover, Germany
| | - Athanasia Warnecke
- Department of Otolaryngology Head and Neck Surgery, Hannover Medical School, Hannover, Germany
- Cluster of Excellence 'Hearing for All', German Research Foundation, Bonn, Germany
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Nieratschker M, Yildiz E, Gerlitz M, Bera S, Gadenstaetter AJ, Kramer AM, Kwiatkowska M, Mistrik P, Landegger LD, Braun S, Schlingensiepen R, Honeder C, Arnoldner C, Rommelspacher H. A preoperative dose of the pyridoindole AC102 improves the recovery of residual hearing in a gerbil animal model of cochlear implantation. Cell Death Dis 2024; 15:531. [PMID: 39060244 PMCID: PMC11282255 DOI: 10.1038/s41419-024-06854-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2024] [Revised: 06/19/2024] [Accepted: 06/20/2024] [Indexed: 07/28/2024]
Abstract
Sensorineural hearing loss (SNHL) is the most common sensory deficit worldwide. Due to the heterogeneity of causes for SNHL, effective treatment options remain scarce, creating an unmet need for novel drugs in the field of otology. Cochlear implantation (CI) currently is the only established method to restore hearing function in profound SNHL and deaf patients. The cochlear implant bypasses the non-functioning sensory hair cells (HCs) and electrically stimulates the neurons of the cochlear nerve. CI also benefits patients with residual hearing by combined electrical and auditory stimulation. However, the insertion of an electrode array into the cochlea induces an inflammatory response, characterized by the expression of pro-inflammatory cytokines, upregulation of reactive oxygen species, and apoptosis and necrosis of HCs, putting residual hearing at risk. Here, we characterize the small molecule AC102, a pyridoindole, for its protective effects on residual hearing in CI. In a gerbil animal model of CI, AC102 significantly improves the recovery of hearing thresholds across multiple frequencies and confines the cochlear trauma to the directly mechanically injured area. In addition, AC102 significantly preserves auditory nerve fibers and inner HC synapses throughout the whole cochlea. In vitro experiments in an ethanol challenged HT22 cell-line revealed significant and dose-responsive anti-apoptotic effects following the treatment of with AC102. Further, AC102 treatment resulted in significant downregulation of the expression of pro-inflammatory cytokines in an organotypic ex vivo model of electrode insertion trauma (EIT). These results suggest that AC102's effects are likely elicited during the inflammatory phase of EIT and mediated by anti-apoptotic and anti-inflammatory properties, highlighting AC102 as a promising compound for hearing preservation during CI. Moreover, since the inflammatory response in CI shares similarities to that in other etiologies of SNHL, AC102 may be inferred as a potential general treatment option for various inner ear conditions.
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Affiliation(s)
- Michael Nieratschker
- Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Vienna, Vienna, Austria
| | - Erdem Yildiz
- Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Vienna, Vienna, Austria
| | - Matthias Gerlitz
- Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Vienna, Vienna, Austria
| | | | - Anselm J Gadenstaetter
- Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Vienna, Vienna, Austria
| | - Anne-Margarethe Kramer
- Center for Biomedical Research and Translational Surgery, Medical University of Vienna, Vienna, Austria
| | | | | | - Lukas D Landegger
- Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Vienna, Vienna, Austria
| | | | | | - Clemens Honeder
- Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Vienna, Vienna, Austria
| | - Christoph Arnoldner
- Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Vienna, Vienna, Austria.
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Berger E, Brandes G, Kaiser O, Reifenrath J, Lenarz T, Wissel K, Durisin M. Induction of cell death by sodium hexachloroplatinate (IV) in the HEI-OC1 cell line, primary rat spiral ganglion cells and rat organ of Corti explants. PLoS One 2024; 19:e0307973. [PMID: 39058727 PMCID: PMC11280268 DOI: 10.1371/journal.pone.0307973] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2024] [Accepted: 07/15/2024] [Indexed: 07/28/2024] Open
Abstract
Although cochlear implants have become a well-established method for patients with sensory neural hearing loss, clinical results indicate that in some cases, corrosion of electrode contacts leads to high impedance that interferes with successful stimulation of the auditory nerve. As it is unclear whether corrosion products induce cell damage, we focused on cell culture models of the organ of Corti cell line (HEI-OC1), rat spiral ganglion cells (SGC) and rat organ of Corti explant (OCex) cultivated from neonatal rat cochleae to characterize the cytotoxicity of sodium hexachloroplatinate (IV) (Na2(PtCl6)). The oxidative activity in HEI-OC1 cells decreased with increasing Na2(PtCl6) concentrations between 8 and 16 ng/μl, and live cell staining with Calcein acetoxymethyl/Ethidium homodimer III revealed an increasing number of cells with disrupted membranes. Ultrastructural evidence of mitophagy followed by necroptosis was detected. Additionally, exposure of the SGC to 15-35 ng/μl Na2(PtCl6) dose-dependently reduced neuronal survival and neuritogenesis, as determined by neurofilament antigen staining. In parallel, staining glial cells and fibroblasts with specific antibodies confirmed the dose-dependent induction of cell death by Na2(PtCl6). Exposure of the OCex to 25-45 ng/μl Na2(PtCl6) resulted in severe concentration-dependent hair cell loss. Our data show for the first time that Na2(PtCl6) induces cell death in a concentration-dependent manner in inner ear cell types and tissues.
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Affiliation(s)
- Elisabeth Berger
- Department of Otorhinolaryngology, Hannover Medical School, Hannover, Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover Medical School, Hannover, Germany
| | - Gudrun Brandes
- Hannover Medical School, Institute of Neuroanatomy and Cell Biology, Hannover, Germany
| | - Odett Kaiser
- Department of Otorhinolaryngology, Hannover Medical School, Hannover, Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover Medical School, Hannover, Germany
| | - Janin Reifenrath
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover Medical School, Hannover, Germany
- Clinic for Orthopaedic Surgery, Hannover Medical School, Hannover, Germany
| | - Thomas Lenarz
- Department of Otorhinolaryngology, Hannover Medical School, Hannover, Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover Medical School, Hannover, Germany
| | - Kirsten Wissel
- Department of Otorhinolaryngology, Hannover Medical School, Hannover, Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover Medical School, Hannover, Germany
| | - Martin Durisin
- Department of Otorhinolaryngology, Hannover Medical School, Hannover, Germany
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover Medical School, Hannover, Germany
- University Clinic of Otolaryngology, Head and Neck Surgery, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany
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Matter L, Abdullaeva OS, Shaner S, Leal J, Asplund M. Bioelectronic Direct Current Stimulation at the Transition Between Reversible and Irreversible Charge Transfer. ADVANCED SCIENCE (WEINHEIM, BADEN-WURTTEMBERG, GERMANY) 2024; 11:e2306244. [PMID: 38460180 PMCID: PMC11251568 DOI: 10.1002/advs.202306244] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Revised: 02/06/2024] [Indexed: 03/11/2024]
Abstract
Many biological processes rely on endogenous electric fields (EFs), including tissue regeneration, cell development, wound healing, and cancer metastasis. Mimicking these biological EFs by applying external direct current stimulation (DCS) is therefore the key to many new therapeutic strategies. During DCS, the charge transfer from electrode to tissue relies on a combination of reversible and irreversible electrochemical processes, which may generate toxic or bio-altering substances, including metal ions and reactive oxygen species (ROS). Poly(3,4-ethylenedioxythiophene) (PEDOT) based electrodes are emerging as suitable candidates for DCS to improve biocompatibility compared to metals. This work addresses whether PEDOT electrodes can be tailored to favor reversible biocompatible charge transfer. To this end, different PEDOT formulations and their respective back electrodes are studied using cyclic voltammetry, chronopotentiometry, and direct measurements of H2O2 and O2. This combination of electrochemical methods sheds light on the time dynamics of reversible and irreversible charge transfer and the relationship between capacitance and ROS generation. The results presented here show that although all electrode materials investigated generate ROS, the onset of ROS can be delayed by increasing the electrode's capacitance via PEDOT coating, which has implications for future bioelectronic devices that allow longer reversibly driven pulse durations during DCS.
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Affiliation(s)
- Lukas Matter
- Department of Microtechnology and NanoscienceChalmers University of TechnologyGothenburgSE 41296Sweden
- Department of Microsystems EngineeringUniversity of FreiburgGeorges‐Köhler‐Allee 20179110FreiburgGermany
- Brainlinks‐Braintools CenterUniversity of FreiburgGeorges‐Köhler‐Allee 20179110FreiburgGermany
- Freiburg Institute for Advanced Studies (FRIAS)University of FreiburgAlbertstraße 1979104FreiburgGermany
| | - Oliya S. Abdullaeva
- Division of Nursing and Medical TechnologyLuleå University of TechnologyLuleåSE 97187Sweden
| | - Sebastian Shaner
- Department of Microsystems EngineeringUniversity of FreiburgGeorges‐Köhler‐Allee 20179110FreiburgGermany
- Brainlinks‐Braintools CenterUniversity of FreiburgGeorges‐Köhler‐Allee 20179110FreiburgGermany
| | - José Leal
- Department of Microsystems EngineeringUniversity of FreiburgGeorges‐Köhler‐Allee 20179110FreiburgGermany
- Brainlinks‐Braintools CenterUniversity of FreiburgGeorges‐Köhler‐Allee 20179110FreiburgGermany
| | - Maria Asplund
- Department of Microtechnology and NanoscienceChalmers University of TechnologyGothenburgSE 41296Sweden
- Department of Microsystems EngineeringUniversity of FreiburgGeorges‐Köhler‐Allee 20179110FreiburgGermany
- Brainlinks‐Braintools CenterUniversity of FreiburgGeorges‐Köhler‐Allee 20179110FreiburgGermany
- Freiburg Institute for Advanced Studies (FRIAS)University of FreiburgAlbertstraße 1979104FreiburgGermany
- Division of Nursing and Medical TechnologyLuleå University of TechnologyLuleåSE 97187Sweden
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O'Malley JT, Wu PZ, Kaur C, Gantz BJ, Hansen MR, Quesnel AM, Liberman MC. Delayed hearing loss after cochlear implantation: Re-evaluating the role of hair cell degeneration. Hear Res 2024; 447:109024. [PMID: 38735179 PMCID: PMC11134194 DOI: 10.1016/j.heares.2024.109024] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 03/18/2024] [Revised: 04/18/2024] [Accepted: 04/26/2024] [Indexed: 05/14/2024]
Abstract
Delayed loss of residual acoustic hearing after cochlear implantation is a common but poorly understood phenomenon due to the scarcity of relevant temporal bone tissues. Prior histopathological analysis of one case of post-implantation hearing loss suggested there were no interaural differences in hair cell or neural degeneration to explain the profound loss of low-frequency hearing on the implanted side (Quesnel et al., 2016) and attributed the threshold elevation to neo-ossification and fibrosis around the implant. Here we re-evaluated the histopathology in this case, applying immunostaining and improved microscopic techniques for differentiating surviving hair cells from supporting cells. The new analysis revealed dramatic interaural differences, with a > 80 % loss of inner hair cells in the cochlear apex on the implanted side, which can account for the post-implantation loss of residual hearing. Apical degeneration of the stria further contributed to threshold elevation on the implanted side. In contrast, spiral ganglion cell survival was reduced in the region of the electrode on the implanted side, but apical counts in the two ears were similar to that seen in age-matched unimplanted control ears. Almost none of the surviving auditory neurons retained peripheral axons throughout the basal half of the cochlea. Relevance to cochlear implant performance is discussed.
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Affiliation(s)
- Jennifer T O'Malley
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, 02114, USA; Dept of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, MA, 02115, USA
| | - Pei-Zhe Wu
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, 02114, USA; Dept of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, MA, 02115, USA
| | - Charanjeet Kaur
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, 02114, USA; Dept of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, MA, 02115, USA
| | - Bruce J Gantz
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, IA, 52242, USA; Department of Neurosurgery, University of Iowa, Iowa City, IA, 52242
| | - Marlan R Hansen
- Department of Otolaryngology-Head and Neck Surgery, University of Iowa, Iowa City, IA, 52242, USA; Department of Neurosurgery, University of Iowa, Iowa City, IA, 52242
| | - Alicia M Quesnel
- Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, 02114, USA; Dept of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, MA, 02115, USA
| | - M Charles Liberman
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, 02114, USA; Dept of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, MA, 02115, USA.
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Yancey KL, Patro A, Smetak M, Perkins EL, Isaacson B, Bennett ML, O'Malley M, Haynes DS, Hunter JB. Evaluating calcium channel blockers and bisphosphonates as otoprotective agents in cochlear implantation hearing preservation candidates. Cochlear Implants Int 2024; 25:131-139. [PMID: 38738388 DOI: 10.1080/14670100.2024.2338003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/14/2024]
Abstract
OBJECTIVES Evaluate potential effects of calcium channel blockers (CCB) and bisphosphonates (BP) on residual hearing following cochlear implantation. METHODS Medications of 303 adult hearing preservation (HP) candidates (low frequency pure tone average [LFPTA] of 125, 250, and 500 Hz ≤80 dB HL) were reviewed. Postimplantation LFPTA of patients taking CCBs and BPs were compared to controls matched by age and preimplantation LFPTA. RESULTS Twenty-six HP candidates were taking a CCB (N = 14) or bisphosphonate (N = 12) at implantation. Median follow-up was 1.37 years (range 0.22-4.64y). Among subjects with initial HP, 29% (N = 2 of 7) CCB users compared to 50% (N = 2 of 4) controls subsequently lost residual hearing 3-6 months later (OR = 0.40, 95% CI = 0.04-4.32, p = 0.58). None of the four BP patients with initial HP experienced delayed loss compared to 50% (N = 2 of 4) controls with initial HP (OR = 0.00, 95% CI = 0.00-1.95, P = 0.43). Two CCB and one BP patients improved to a LFPTA <80 dB HL following initial unaided thresholds that suggested loss of residual hearing. DISCUSSION There were no significant differences in the odds of delayed loss of residual hearing with CCBs or BPs. CONCLUSION Further investigation into potential otoprotective adjuvants for maintaining residual hearing following initial successful hearing preservation is warranted, with larger cohorts and additional CCB/BP agents.
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Affiliation(s)
- Kristen L Yancey
- Department of Otolaryngology-Head and Neck Surgery, Weill Cornell Medical Center/New York Presbyterian Hospital, New York, NY, USA
| | - Ankita Patro
- Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Miriam Smetak
- Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Elizabeth L Perkins
- Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Brandon Isaacson
- Department of Otolaryngology-Head and Neck Surgery, University of Texas Southwestern Medical Center, Dallas, TX, USA
| | - Marc L Bennett
- Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Matthew O'Malley
- Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - David S Haynes
- Department of Otolaryngology-Head and Neck Surgery, Vanderbilt University Medical Center, Nashville, TN, USA
| | - Jacob B Hunter
- Department of Otolaryngology-Head and Neck Surgery, Thomas Jefferson University Hospital, Philadelphia, PA, USA
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Geerardyn A, Zhu M, Klabbers T, Huinck W, Mylanus E, Nadol JB, Verhaert N, Quesnel AM. Human Histology after Structure Preservation Cochlear Implantation via Round Window Insertion. Laryngoscope 2024; 134:945-953. [PMID: 37493203 DOI: 10.1002/lary.30900] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Revised: 06/22/2023] [Accepted: 07/05/2023] [Indexed: 07/27/2023]
Abstract
OBJECTIVES Current surgical techniques aim to preserve intracochlear structures during cochlear implant (CI) insertion to maintain residual cochlear function. The optimal technique to minimize damage, however, is still under debate. The aim of this study is to histologically compare insertional trauma and intracochlear tissue formation in humans with a CI implanted via different insertion techniques. METHODS One recent temporal bone from a donor who underwent implantation of a full-length CI (576°) via round window (RW) insertion was compared with nine cases implanted via cochleostomy (CO) or extended round window (ERW) approach. Insertional trauma was assessed on H&E-stained histological sections. 3D reconstructions were generated and virtually re-sectioned to measure intracochlear volumes of fibrosis and neo-ossification. RESULTS The RW insertion case showed electrode translocation via the spiral ligament. 2/9 CO/ERW cases showed no insertional trauma. The total volume of the cochlea occupied by fibro-osseous tissue was 10.8% in the RW case compared with a mean of 30.6% (range 8.7%-44.8%, N = 9) in the CO/ERW cases. The difference in tissue formation in the basal 5 mm of scala tympani, however, was even more pronounced when the RW case (12.3%) was compared with the cases with a CO/ERW approach (mean of 93.8%, range 81% to 100%, N = 9). CONCLUSIONS Full-length CI insertions via the RW can be minimally traumatic at the cochlear base without inducing extensive fibro-osseous tissue formation locally. The current study further supports the hypothesis that drilling of the cochleostomy with damage to the endosteum incites a local tissue reaction. LEVEL OF EVIDENCE 4: Case-control study Laryngoscope, 134:945-953, 2024.
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Affiliation(s)
- Alexander Geerardyn
- Department of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, Massachusetts, U.S.A
- Otopathology Laboratory, Massachusetts Eye and Ear, Boston, Massachusetts, U.S.A
- ExpORL, Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium
| | - MengYu Zhu
- Otopathology Laboratory, Massachusetts Eye and Ear, Boston, Massachusetts, U.S.A
| | - Tim Klabbers
- Department of Otorhinolaryngology, Radboudumc, Nijmegen, the Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Nijmegen, the Netherlands
| | - Wendy Huinck
- Department of Otorhinolaryngology, Radboudumc, Nijmegen, the Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Nijmegen, the Netherlands
| | - Emmanuel Mylanus
- Department of Otorhinolaryngology, Radboudumc, Nijmegen, the Netherlands
- Donders Institute for Brain, Cognition and Behaviour, Nijmegen, the Netherlands
| | - Joseph B Nadol
- Department of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, Massachusetts, U.S.A
- Otopathology Laboratory, Massachusetts Eye and Ear, Boston, Massachusetts, U.S.A
| | - Nicolas Verhaert
- ExpORL, Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium
| | - Alicia M Quesnel
- Department of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, Massachusetts, U.S.A
- Otopathology Laboratory, Massachusetts Eye and Ear, Boston, Massachusetts, U.S.A
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Rahman MT, Mostaert BJ, Hunger B, Saha U, Claussen AD, Razu I, Nasrin F, Khan NA, Eckard P, Coleman S, Oleson J, Kirk JR, Hirose K, Hansen MR. Contribution of macrophages to neural survival and intracochlear tissue remodeling responses following cochlear implantation. J Neuroinflammation 2023; 20:266. [PMID: 37974203 PMCID: PMC10652501 DOI: 10.1186/s12974-023-02955-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2023] [Accepted: 11/10/2023] [Indexed: 11/19/2023] Open
Abstract
BACKGROUND Cochlear implants (CIs) restore hearing to deafened patients. The foreign body response (FBR) following cochlear implantation (post-CI) comprises an infiltration of macrophages, other immune and non-immune cells, and fibrosis into the scala tympani, a space that is normally devoid of cells. This FBR is associated with negative effects on CI outcomes including increased electrode impedances and loss of residual acoustic hearing. This study investigates the extent to which macrophage depletion by an orally administered CSF-1R specific kinase (c-FMS) inhibitor, PLX-5622, modulates the tissue response to CI and neural health. MAIN TEXT 10- to 12-week-old CX3CR1 + /GFP Thy1 + /YFP mice on C57BL/6J/B6 background was fed chow containing 1200 mg/kg PLX5622 or control chow for the duration of the study. 7 days after starting the diet, 3-channel cochlear implants were implanted in the ear via the round window. Serial impedance and neural response telemetry (NRT) measurements were acquired throughout the study. Electric stimulation began 7 days post-CI until 28 days post-CI for 5 h/day, 5 days/week, with programming guided by NRT and behavioral responses. Cochleae harvested at 10, 28 or 56 days post-CI were cryosectioned and labeled with an antibody against α-smooth muscle actin (α-SMA) to identify myofibroblasts and quantify the fibrotic response. Using IMARIS image analysis software, the outlines of scala tympani, Rosenthal canal, modiolus, and lateral wall for each turn were traced manually to measure region volume. The density of nuclei, CX3CR1 + macrophages, Thy1 + spiral ganglion neuron (SGN) numbers, and the ratio of the α-SMA + volume/scala tympani volume were calculated. Cochlear implantation in control diet subjects caused infiltration of cells, including macrophages, into the cochlea. Fibrosis was evident in the scala tympani adjacent to the electrode array. Mice fed PLX5622 chow showed reduced macrophage infiltration throughout the implanted cochleae across all time points. However, scala tympani fibrosis was not reduced relative to control diet subjects. Further, mice treated with PLX5622 showed increased electrode impedances compared to controls. Finally, treatment with PLX5622 decreased SGN survival in implanted and contralateral cochleae. CONCLUSION The data suggest that macrophages play an important role in modulating the intracochlear tissue response following CI and neural survival.
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Affiliation(s)
- Muhammad Taifur Rahman
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Brian J Mostaert
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Bryce Hunger
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Utsow Saha
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Alexander D Claussen
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Ibrahim Razu
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Farjana Nasrin
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Nashwaan Ali Khan
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Peter Eckard
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA
| | - Sarah Coleman
- Department of Biostatistics, The University of Iowa, Iowa City, IA, USA
| | - Jacob Oleson
- Department of Biostatistics, The University of Iowa, Iowa City, IA, USA
| | | | - Keiko Hirose
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St. Louis, MO, USA
| | - Marlan R Hansen
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, Iowa City, IA, 52242, USA.
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Sagi V, Kosaraju N, Moore LS, Mulders JY, Solyali M, Ma X, Regula DP, Hooper JE, Stankovic KM. Mortui vivos docent: a modern revival of temporal bone plug harvests. Front Neurosci 2023; 17:1242831. [PMID: 37886674 PMCID: PMC10598599 DOI: 10.3389/fnins.2023.1242831] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2023] [Accepted: 09/04/2023] [Indexed: 10/28/2023] Open
Abstract
Human temporal bones (HTBs) are invaluable resources for the study of otologic disorders and for evaluating novel treatment approaches. Given the high costs and technical expertise required to collect and process HTBs, there has been a decline in the number of otopathology laboratories. Our objective is to encourage ongoing study of HTBs by outlining the necessary steps to establish a pipeline for collection and processing of HTBs. In this methods manuscript, we: (1) provide the design of a temporal bone plug sawblade that can be used to collect specimens from autopsy donors; (2) establish that decalcification time can be dramatically reduced from 9 to 3 months if ethylenediaminetetraacetic acid is combined with microwave tissue processing and periodic bone trimming; (3) show that serial sections of relatively-rapidly decalcified HTBs can be successfully immunostained for key inner ear proteins; (4) demonstrate how to drill down a HTB to the otic capsule within a few hours so that subsequent decalcification time can be further reduced to only weeks. We include photographs and videos to facilitate rapid dissemination of the developed methods. Collected HTBs can be used for many purposes, including, but not limited to device testing, imaging studies, education, histopathology, and molecular studies. As new technology develops, it is imperative to continue studying HTBs to further our understanding of the cellular and molecular underpinnings of otologic disorders.
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Affiliation(s)
- Varun Sagi
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Nikitha Kosaraju
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
- David Geffen School of Medicine at UCLA, Los Angeles, CA, United States
| | - Lindsay S. Moore
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Jip Y. Mulders
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
| | - Mehmet Solyali
- Department of Physics, Stanford University School of Humanities and Sciences, Stanford, CA, United States
| | - Xiaojie Ma
- Department of Otolaryngology – Head and Neck Surgery, Massachusetts Eye and Ear and Harvard Medical School, Boston, MA, United States
| | - Donald P. Regula
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, United States
| | - Jody E. Hooper
- Department of Pathology, Stanford University School of Medicine, Stanford, CA, United States
| | - Konstantina M. Stankovic
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, United States
- Department of Neurosurgery, Stanford University School of Medicine, Stanford, CA, United States
- Wu Tsai Neurosciences Institute, Stanford University, Stanford, CA, United States
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11
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Vibert D, Kompis M, Caversaccio M, Mantokoudis G. Vestibular function, subjective complaints, perceived disability in daily life, and sports activities in patients with cochlear implants performed during childhood: a prospective cross-section study. Acta Otolaryngol 2023; 143:735-741. [PMID: 37897347 DOI: 10.1080/00016489.2023.2268159] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Accepted: 09/28/2023] [Indexed: 10/30/2023]
Abstract
BACKGROUND Vestibular function (VF) in patients with cochlear implantation (CI) performed during childhood is underinvestigated. OBJECTIVE To study VF in patients receiving CI during childhood. MATERIAL & METHODS Sixty patients (22 females) from 7-34 years old, unilaterally (n = 21) and bilaterally (n = 39) implanted, were included. Deafness was congenital (n = 45), consequential to meningitis (n = 3), skull fracture (n = 1), perinatal CMV infection (n = 1), ototoxic drugs (n = 1), unknown etiology (n = 9). VF was measured between 1 to 22 years after implantation, including calorics, v-HIT, c-VEMPS. Dizziness handicap inventory (DHI), age at independent walking(IW), sport activities were also investigated. RESULTS Nine CI-patients (15%) reported dizziness/vertigo either prior or months to years after surgery. Comparison between symptomatic (15%), asymptomatic (85%), uni-bilaterally CI-patients showed no significant difference on VF's impairment for calorics (p = .603) and v-HIT (p = 1). Symptoms were not related to vestibular impairment. Age at implantation (p = 0.956), uni- bilateral (p = .32), simultaneous versus sequential (p = .134) did not influence IW age. DHI showed a tendency for being symptomatic at higher implantation age. Interval between CI, IWage, current age between surgery and vestibular evaluation did not have a significant effect on symptomatology. CONCLUSION & SIGNIFICANCE This first middle to long-term evaluation of the VF in CI-patients, implanted in childhood, pointed out that 85% of patients were asymptomatic, with a mean time of >10 years after surgery. Vestibular impairment and symptoms seem to be mainly due to the underlying inner ear's disease rather than surgery.
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Affiliation(s)
- Dominique Vibert
- Department of Otorhinolaryngology, Head & Neck Surgery, Inselspital, University of Bern, Switzerland
| | - Martin Kompis
- Department of Otorhinolaryngology, Head & Neck Surgery, Inselspital, University of Bern, Switzerland
| | - Marco Caversaccio
- Department of Otorhinolaryngology, Head & Neck Surgery, Inselspital, University of Bern, Switzerland
| | - Georgios Mantokoudis
- Department of Otorhinolaryngology, Head & Neck Surgery, Inselspital, University of Bern, Switzerland
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12
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Bruschke S, Baumann U, Stöver T. Residual low-frequency hearing after early device activation in cochlear implantation. Eur Arch Otorhinolaryngol 2023; 280:3977-3985. [PMID: 36943438 PMCID: PMC10382339 DOI: 10.1007/s00405-023-07887-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2022] [Accepted: 02/14/2023] [Indexed: 03/23/2023]
Abstract
PURPOSE The cochlear implant (CI) is a standard treatment for patients with severe to profound hearing loss. In recent years, early device activation of the sound processor after 2-3 days following surgery has been established. The aim of this study is to evaluate the residual hearing of CI patients with substantial preoperative low-frequency hearing after early device activation over a period of 12 months. METHODS Results were compared between an early fitted group (EF) with device activation to less than 15 days after CI surgery and a control group (CG) with device activation after 3-6 weeks. In total, 57 patients were divided into EF group (n = 32), and CG (n = 25). Low-frequency residual hearing and speech recognition in quiet and in noise were compared over an observation period of 12 months. RESULTS No significant difference (p > 0.05) in the residual low-frequency hearing PTAlow between EF and CG was found, neither preoperatively (EF 33.2 dB HL/CG 35.0 dB HL), nor postoperatively (EF 46.8 dB HL/CG 46.2 dB HL). In both groups, postoperative residual hearing decreased compared to preoperative and remained stable within the first year after CI surgery. Furthermore, both groups showed no significant differences (p > 0.05) in speech recognition in quiet and in noise within the first year. CONCLUSION Early device activation is feasible in CI patients with preoperative low-frequency residual hearing, without an additional effect on postoperative hearing preservation.
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Affiliation(s)
- Stefanie Bruschke
- Goethe University Frankfurt, University Hospital, ENT Department, Theodor-Stern-Kai 7, 60590, Frankfurt a. M, Germany.
| | - Uwe Baumann
- Goethe University Frankfurt, University Hospital, ENT Department, Theodor-Stern-Kai 7, 60590, Frankfurt a. M, Germany
| | - Timo Stöver
- Goethe University Frankfurt, University Hospital, ENT Department, Theodor-Stern-Kai 7, 60590, Frankfurt a. M, Germany
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Almasri RM, Ladouceur F, Mawad D, Esrafilzadeh D, Firth J, Lehmann T, Poole-Warren LA, Lovell NH, Al Abed A. Emerging trends in the development of flexible optrode arrays for electrophysiology. APL Bioeng 2023; 7:031503. [PMID: 37692375 PMCID: PMC10491464 DOI: 10.1063/5.0153753] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2023] [Accepted: 08/08/2023] [Indexed: 09/12/2023] Open
Abstract
Optical-electrode (optrode) arrays use light to modulate excitable biological tissues and/or transduce bioelectrical signals into the optical domain. Light offers several advantages over electrical wiring, including the ability to encode multiple data channels within a single beam. This approach is at the forefront of innovation aimed at increasing spatial resolution and channel count in multichannel electrophysiology systems. This review presents an overview of devices and material systems that utilize light for electrophysiology recording and stimulation. The work focuses on the current and emerging methods and their applications, and provides a detailed discussion of the design and fabrication of flexible arrayed devices. Optrode arrays feature components non-existent in conventional multi-electrode arrays, such as waveguides, optical circuitry, light-emitting diodes, and optoelectronic and light-sensitive functional materials, packaged in planar, penetrating, or endoscopic forms. Often these are combined with dielectric and conductive structures and, less frequently, with multi-functional sensors. While creating flexible optrode arrays is feasible and necessary to minimize tissue-device mechanical mismatch, key factors must be considered for regulatory approval and clinical use. These include the biocompatibility of optical and photonic components. Additionally, material selection should match the operating wavelength of the specific electrophysiology application, minimizing light scattering and optical losses under physiologically induced stresses and strains. Flexible and soft variants of traditionally rigid photonic circuitry for passive optical multiplexing should be developed to advance the field. We evaluate fabrication techniques against these requirements. We foresee a future whereby established telecommunications techniques are engineered into flexible optrode arrays to enable unprecedented large-scale high-resolution electrophysiology systems.
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Affiliation(s)
- Reem M. Almasri
- Graduate School of Biomedical Engineering, UNSW, Sydney, NSW 2052, Australia
| | | | - Damia Mawad
- School of Materials Science and Engineering, UNSW, Sydney, NSW 2052, Australia
| | - Dorna Esrafilzadeh
- Graduate School of Biomedical Engineering, UNSW, Sydney, NSW 2052, Australia
| | - Josiah Firth
- Australian National Fabrication Facility, UNSW, Sydney, NSW 2052, Australia
| | - Torsten Lehmann
- School of Electrical Engineering and Telecommunications, UNSW, Sydney, NSW 2052, Australia
| | | | | | - Amr Al Abed
- Graduate School of Biomedical Engineering, UNSW, Sydney, NSW 2052, Australia
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14
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Braack KJ, Miles T, Amat F, Brown DJ, Atlas MD, Kuthubutheen J, Mulders WH, Prêle CM. Using x-ray micro computed tomography to quantify intracochlear fibrosis after cochlear implantation in a Guinea pig model. Heliyon 2023; 9:e19343. [PMID: 37662829 PMCID: PMC10474428 DOI: 10.1016/j.heliyon.2023.e19343] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2023] [Revised: 08/07/2023] [Accepted: 08/18/2023] [Indexed: 09/05/2023] Open
Abstract
Cochlear implants (CIs) allow individuals with profound hearing loss to understand speech and perceive sounds. However, not all patients obtain the full benefits that CIs can provide and the cause of this disparity is not fully understood. One possible factor for the variability in outcomes after cochlear implantation, is the development of fibrotic scar tissue around the implanted electrode. It has been hypothesised that limiting the extent of fibrosis after implantation may improve overall CI function, and longevity of the device. Currently, histology is often used to quantify the extent of intracochlear tissue growth after implantation however this method is labour intensive, time-consuming, often involves significant user bias, and causes physical distortion of the fibrosis. Therefore, this study aimed to evaluate x-ray micro computed tomography (μCT) as a method to measure the amount and distribution of fibrosis in a guinea pig model of cochlear implantation. Adult guinea pigs were implanted with an inactive electrode, and cochleae harvested eight weeks later (n = 7) and analysed using μCT, to quantify the extent of tissue reaction, followed by histological analysis to confirm that the tissue was indeed fibrotic. Cochleae harvested from an additional six animals following implantation were analysed by μCT, before and after contrast staining with osmium tetroxide (OsO4), to enhance the visualisation of soft tissues within the cochlea, including the tissue reaction. Independent analysis by two observers showed that the quantification method was robust and provided additional information on the distribution of the response within the cochlea. Histological analysis revealed that μCT visualised dense collagenous material and new bone formation but did not capture loose, areolar fibrotic tissue. Treatment with OsO4 significantly enhanced the visible tissue reaction detected using μCT. Overall, μCT is an alternative and reliable method that can be used to quantify the extent of the CI-induced intracochlear tissue response and will be a useful tool for the in vivo assessment of novel anti-fibrotic treatments.
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Affiliation(s)
- Kady J. Braack
- School of Human Sciences, University of Western Australia, Crawley, WA 6009, Australia
| | - Tylah Miles
- Institute for Respiratory Health, University of Western Australia, Nedlands, WA 6009, Australia
| | - Farah Amat
- School of Human Sciences, University of Western Australia, Crawley, WA 6009, Australia
| | - Daniel J. Brown
- Curtin Medical School, Curtin University, Bentley, WA 6102, Australia
| | - Marcus D. Atlas
- Curtin Medical School, Curtin University, Bentley, WA 6102, Australia
- Medical School, University of Western Australia, Crawley, WA 6009, Australia
- Ear Science Institute Australia, Subiaco, WA 6008, Australia
| | - Jafri Kuthubutheen
- Medical School, University of Western Australia, Crawley, WA 6009, Australia
- Department of Otolaryngology Head and Neck Surgery, Sir Charles Gairdner Hospital, Hospital Avenue, Nedlands, WA 6009, Australia
| | | | - Cecilia M. Prêle
- Institute for Respiratory Health, University of Western Australia, Nedlands, WA 6009, Australia
- Ear Science Institute Australia, Subiaco, WA 6008, Australia
- School of Medical, Molecular and Forensic Sciences, Murdoch University, Murdoch, WA 6150, Australia
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15
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Matter L, Harland B, Raos B, Svirskis D, Asplund M. Generation of direct current electrical fields as regenerative therapy for spinal cord injury: A review. APL Bioeng 2023; 7:031505. [PMID: 37736015 PMCID: PMC10511262 DOI: 10.1063/5.0152669] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2023] [Accepted: 08/21/2023] [Indexed: 09/23/2023] Open
Abstract
Electrical stimulation (ES) shows promise as a therapy to promote recovery and regeneration after spinal cord injury. ES therapy establishes beneficial electric fields (EFs) and has been investigated in numerous studies, which date back nearly a century. In this review, we discuss the various engineering approaches available to generate regenerative EFs through direct current electrical stimulation and very low frequency electrical stimulation. We highlight the electrode-tissue interface, which is important for the appropriate choice of electrode material and stimulator circuitry. We discuss how to best estimate and control the generated field, which is an important measure for comparability of studies. Finally, we assess the methods used in these studies to measure functional recovery after the injury and treatment. This work reviews studies in the field of ES therapy with the goal of supporting decisions regarding best stimulation strategy and recovery assessment for future work.
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Affiliation(s)
- Lukas Matter
- Author to whom correspondence should be addressed:
| | - Bruce Harland
- School of Pharmacy, The University of Auckland, NZ 1023 Auckland, New Zealand
| | - Brad Raos
- School of Pharmacy, The University of Auckland, NZ 1023 Auckland, New Zealand
| | - Darren Svirskis
- School of Pharmacy, The University of Auckland, NZ 1023 Auckland, New Zealand
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Schuerch K, Wimmer W, Rummel C, Caversaccio MD, Weder S. Objective evaluation of intracochlear electrocochleography: repeatability, thresholds, and tonotopic patterns. Front Neurol 2023; 14:1181539. [PMID: 37621854 PMCID: PMC10446839 DOI: 10.3389/fneur.2023.1181539] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/07/2023] [Accepted: 06/26/2023] [Indexed: 08/26/2023] Open
Abstract
Introduction Intracochlear electrocochleography (ECochG) is increasingly being used to measure residual inner ear function in cochlear implant (CI) recipients. ECochG signals reflect the state of the inner ear and can be measured during implantation and post-operatively. The aim of our study was to apply an objective deep learning (DL)-based algorithm to assess the reproducibility of longitudinally recorded ECochG signals, compare them with audiometric hearing thresholds, and identify signal patterns and tonotopic behavior. Methods We used a previously published objective DL-based algorithm to evaluate post-operative intracochlear ECochG signals collected from 21 ears. The same measurement protocol was repeated three times over 3 months. Additionally, we measured the pure-tone thresholds and subjective loudness estimates for correlation with the objectively detected ECochG signals. Recordings were made on at least four electrodes at three intensity levels. We extracted the electrode positions from computed tomography (CT) scans and used this information to evaluate the tonotopic characteristics of the ECochG responses. Results The objectively detected ECochG signals exhibited substantial repeatability over a 3-month period (bias-adjusted kappa, 0.68; accuracy 83.8%). Additionally, we observed a moderate-to-strong dependence of the ECochG thresholds on audiometric and subjective hearing levels. Using radiographically determined tonotopic measurement positions, we observed a tendency for tonotopic allocation with a large variance. Furthermore, maximum ECochG amplitudes exhibited a substantial basal shift. Regarding maximal amplitude patterns, most subjects exhibited a flat pattern with amplitudes evenly distributed over the electrode carrier. At higher stimulation frequencies, we observed a shift in the maximum amplitudes toward the basal turn of the cochlea. Conclusions We successfully implemented an objective DL-based algorithm for evaluating post-operative intracochlear ECochG recordings. We can only evaluate and compare ECochG recordings systematically and independently from experts with an objective analysis. Our results help to identify signal patterns and create a better understanding of the inner ear function with the electrode in place. In the next step, the algorithm can be applied to intra-operative measurements.
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Affiliation(s)
- Klaus Schuerch
- Department of ENT, Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Hearing Research Laboratory, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Wilhelm Wimmer
- Department of Otorhinolaryngology, TUM School of Medicine, Klinikum Rechts der Isar, Technical University of Munich, Munich, Germany
| | - Christian Rummel
- Support Center for Advanced Neuroimaging (SCAN), University Institute for Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Marco Domenico Caversaccio
- Department of ENT, Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Hearing Research Laboratory, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Stefan Weder
- Department of ENT, Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Hearing Research Laboratory, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
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17
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Rahman MT, Mostaert BJ, Hunger B, Saha U, Claussen AD, Razu I, Farjana N, Khan NA, Coleman S, Oleson J, Kirk J, Keiko H, Hansen MR. Contribution of macrophages to intracochlear tissue remodeling responses following cochlear implantation and neural survival. RESEARCH SQUARE 2023:rs.3.rs-3065630. [PMID: 37461619 PMCID: PMC10350110 DOI: 10.21203/rs.3.rs-3065630/v1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 07/24/2023]
Abstract
Introduction Cochlear implants (CIs) restore hearing to deafened patients. The foreign body response (FBR) following cochlear implantation (post-CI) comprises an infiltration of macrophages, other immune and non-immune cells, and fibrosis into the scala tympani; a space that is normally devoid of cells. This FBR is associated with negative effects on CI outcomes including increased electrode impedances and loss of residual acoustic hearing. This study investigates the extent to which macrophage depletion by an orally administered CSF-1R specific kinase (c-FMS) inhibitor, PLX-5622, modulates the tissue response to CI and neural health. Materials and methods 10-12-week-old CX3CR1+/GFP Thy1+/YFP mice on C57Bl6 background with normal hearing were fed chow containing 1200 mg/kg PLX5622 or control chow for the duration of the study. 7-days after starting the diet, 3-channel cochlear implants were implanted ear via the round window. Serial impedance and neural response telemetry (NRT) measurements were acquired throughout the study. Electric stimulation began 7 days post-CI until 28- days post-CI for 5 hrs/day, 5 days/week, with programming guided by NRT and behavioral responses. Cochleae harvested at 10-, 28- or 56-days post-CI were cryosectioned and labeled with antibody against α-smooth muscle actin (α-SMA) to identify myofibroblasts and quantify the fibrotic response. Using IMARIS image analysis software, the outlines of scala tympani, Rosenthal canal, modiolus and lateral wall for each turn were traced manually to measure region volume. Density of nuclei, CX3CR1+ macrophages, Thy1+ spiral ganglion neuron (SGN) numbers and ratio of volume of α-SMA+ space/volume of scala tympani were calculated. Results Cochlear implantation in control diet subjects caused infiltration of cells, including macrophages, into the cochlea: this response was initially diffuse throughout the cochlea and later localized to the scala tympani of the basal turn by 56-days post-CI. Fibrosis was evident in the scala tympani adjacent to the electrode array. Mice fed PLX5622 chow showed reduced macrophage infiltration throughout the implanted cochleae across all timepoints. However, scala tympani fibrosis was not reduced relative to control diet subjects. Further, mice treated with PLX5622 showed increased electrode impedances compared to controls. Finally, treatment with PLX5622 decreased SGN survival in implanted and contralateral cochleae. Discussion The data suggest that macrophages play an important role in modulating the intracochlear tissue response following CI and neural survival.
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Affiliation(s)
| | - Brain J Mostaert
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | - Bryce Hunger
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | - Utsow Saha
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | | | - Ibrahim Razu
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | - Nasrin Farjana
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | - Nashwaan Ali Khan
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
| | - Sarah Coleman
- Department of Statistics, The University of Iowa, IA
| | - Jackob Oleson
- Department of Statistics, The University of Iowa, IA
| | | | - Hirose Keiko
- Department of Otolaryngology-Head and Neck Surgery, Washington University School of Medicine, St Louis, MO
| | - Marlan R Hansen
- Department of Otolaryngology-Head and Neck Surgery, The University of Iowa, IA
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18
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Schraivogel S, Aebischer P, Weder S, Caversaccio M, Wimmer W. Cochlear implant electrode impedance subcomponents as biomarker for residual hearing. Front Neurol 2023; 14:1183116. [PMID: 37288065 PMCID: PMC10242064 DOI: 10.3389/fneur.2023.1183116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Accepted: 04/25/2023] [Indexed: 06/09/2023] Open
Abstract
Introduction and objectives Maintaining the structural integrity of the cochlea and preserving residual hearing is crucial for patients, especially for those for whom electric acoustic stimulation is intended. Impedances could reflect trauma due to electrode array insertion and therefore could serve as a biomarker for residual hearing. The aim of this study is to evaluate the association between residual hearing and estimated impedance subcomponents in a known collective from an exploratory study. Methods A total of 42 patients with lateral wall electrode arrays from the same manufacturer were included in the study. For each patient, we used data from audiological measurements to compute residual hearing, impedance telemetry recordings to estimate near and far-field impedances using an approximation model, and computed tomography scans to extract anatomical information about the cochlea. We assessed the association between residual hearing and impedance subcomponent data using linear mixed-effects models. Results The progression of impedance subcomponents showed that far-field impedance was stable over time compared to near-field impedance. Low-frequency residual hearing demonstrated the progressive nature of hearing loss, with 48% of patients showing full or partial hearing preservation after 6 months of follow-up. Analysis revealed a statistically significant negative effect of near-field impedance on residual hearing (-3.81 dB HL per kΩ; p < 0.001). No significant effect of far-field impedance was found. Conclusion Our findings suggest that near-field impedance offers higher specificity for residual hearing monitoring, while far-field impedance was not significantly associated with residual hearing. These results highlight the potential of impedance subcomponents as objective biomarkers for outcome monitoring in cochlear implantation.
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Affiliation(s)
- Stephan Schraivogel
- Hearing Research Laboratory, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
- Department of ENT—Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Philipp Aebischer
- Hearing Research Laboratory, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
- Department of ENT—Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Stefan Weder
- Department of ENT—Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Marco Caversaccio
- Hearing Research Laboratory, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
- Department of ENT—Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Wilhelm Wimmer
- Department of ENT—Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Department of Otorhinolaryngology, TUM School of Medicine, Klinikum Rechts der Isar, Technical University of Munich, Munich, Germany
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19
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Findlay C, Edwards M, Hough K, Grasmeder M, Newman TA. Leveraging real-world data to improve cochlear implant outcomes: Is the data available? Cochlear Implants Int 2023:1-12. [PMID: 37088565 DOI: 10.1080/14670100.2023.2198792] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/25/2023]
Abstract
OBJECTIVES A small but persistent proportion of individuals do not gain the expected benefit from cochlear implants(CI). A step-change in the understanding of factors affecting outcomes could come through data science. This study evaluates clinical data capture to assess the quality and utility of CI user's health records for data science, by assessing the recording of otitis media. Otitis media was selected as it is associated with the development of sensorineural hearing loss and may affect cochlear implant outcomes. METHODS A retrospective service improvement project evaluating the medical records of 594 people with a CI under the care of the University of Southampton Auditory Implant Service between 2014 and 2020. RESULTS The clinical records are suitable for data science research. Of the cohort studied 20% of Adults and more than 40% of the paediatric cases have a history of middle ear inflammation. DISCUSSION Data science has potential to improve cochlear implant outcomes and improve understanding of the mechanisms underlying poor performance, through retrospective secondary analysis of real-world data. CONCLUSION Implant centres and the British Cochlear Implant Group National Hearing Implant Registry are urged to consider the importance of consistently and accurate recording of patient data over time for each CI user. Data where links to hearing loss have been identified, such as middle ear inflammation, may be particularly valuable in future analyses and to inform clinical trials.
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Affiliation(s)
- Callum Findlay
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Building 85, Highfield Campus, Southampton S017 1BJ, UK
- Department of Otolaryngology, University Hospital Southampton NHS FT, Tremona Road, Southampton SO16 6YD, UK
| | - Mathew Edwards
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Building 85, Highfield Campus, Southampton S017 1BJ, UK
| | - Kate Hough
- Faculty of Engineering and Physical Sciences, Highfield Campus, University of Southampton, Building 85, Southampton, UK
| | - Mary Grasmeder
- Faculty of Physical Sciences, Highfield Campus, University of Southampton Auditory Implant Services, B19, Southampton SO171BJ, UK
| | - Tracey A Newman
- Clinical and Experimental Sciences, Faculty of Medicine, University of Southampton, Building 85, Highfield Campus, Southampton S017 1BJ, UK
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20
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Kirk JR, Smyth D, Dueck WF. A new paradigm of hearing loss and preservation with cochlear implants: Learnings from fundamental studies and clinical research. Hear Res 2023; 433:108769. [PMID: 37120894 DOI: 10.1016/j.heares.2023.108769] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/20/2022] [Revised: 02/18/2023] [Accepted: 04/15/2023] [Indexed: 05/02/2023]
Abstract
In 2010 Cochlear initiated a coordinated preclinical research program to identify the factors and underlying mechanisms of acoustic hearing loss following cochlear implantation and device use. At its inception the program was structured around several major hypotheses implicated in the loss of acoustic hearing. The understanding of causes evolved over the course of the program, leading to an increased appreciation of the role of the biological response in post-implant hearing loss. A systematic approach was developed which mapped the cochlear implant journey along a timeline that considers all events in an individual's hearing history. By evaluating the available data in this context, rather than by discrete hypothesis testing, causative and associated factors may be more readily detected. This approach presents opportunities for more effective research management and may aid in identifying new prospects for intervention. Many of the outcomes of the research program apply beyond preservation of acoustic hearing to factors important to overall cochlear health and considerations for future therapies.
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Affiliation(s)
- Jonathon R Kirk
- Cochlear Limited, 1 University Avenue, Macquarie University, NSW 2109, Australia.
| | - Daniel Smyth
- Cochlear Limited, 1 University Avenue, Macquarie University, NSW 2109, Australia
| | - Wolfram F Dueck
- Cochlear Limited, 1 University Avenue, Macquarie University, NSW 2109, Australia
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21
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Schuerch K, Wimmer W, Dalbert A, Rummel C, Caversaccio M, Mantokoudis G, Gawliczek T, Weder S. An intracochlear electrocochleography dataset - from raw data to objective analysis using deep learning. Sci Data 2023; 10:157. [PMID: 36949075 PMCID: PMC10033652 DOI: 10.1038/s41597-023-02055-9] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/27/2022] [Accepted: 03/08/2023] [Indexed: 03/24/2023] Open
Abstract
Electrocochleography (ECochG) measures electrophysiological inner ear potentials in response to acoustic stimulation. These potentials reflect the state of the inner ear and provide important information about its residual function. For cochlear implant (CI) recipients, we can measure ECochG signals directly within the cochlea using the implant electrode. We are able to perform these recordings during and at any point after implantation. However, the analysis and interpretation of ECochG signals are not trivial. To assist the scientific community, we provide our intracochlear ECochG data set, which consists of 4,924 signals recorded from 46 ears with a cochlear implant. We collected data either immediately after electrode insertion or postoperatively in subjects with residual acoustic hearing. This data descriptor aims to provide the research community access to our comprehensive electrophysiological data set and algorithms. It includes all steps from raw data acquisition to signal processing and objective analysis using Deep Learning. In addition, we collected subject demographic data, hearing thresholds, subjective loudness levels, impedance telemetry, radiographic findings, and classification of ECochG signals.
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Affiliation(s)
- Klaus Schuerch
- Department of ENT, Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Hearing Research Laboratory, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Wilhelm Wimmer
- Department of ENT, Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Hearing Research Laboratory, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Adrian Dalbert
- Department of Otorhinolaryngology, Head&Neck Surgery, University Hospital Zurich, University of Zurich, Zurich, Switzerland
| | - Christian Rummel
- Support Center for Advanced Neuroimaging (SCAN), University Institute for Diagnostic and Interventional Neuroradiology, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Marco Caversaccio
- Department of ENT, Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- Hearing Research Laboratory, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
| | - Georgios Mantokoudis
- Department of ENT, Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Tom Gawliczek
- Department of ENT, Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Stefan Weder
- Department of ENT, Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland.
- Hearing Research Laboratory, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland.
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22
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Evaluation of a Less Invasive Cochlear Implant Surgery in OPA1 Mutations Provoking Deafblindness. Genes (Basel) 2023; 14:genes14030627. [PMID: 36980899 PMCID: PMC10048538 DOI: 10.3390/genes14030627] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2022] [Revised: 02/10/2023] [Accepted: 02/27/2023] [Indexed: 03/06/2023] Open
Abstract
Cochlear implantation (CI) for deafblindness may have more impact than for non-syndromic hearing loss. Deafblind patients have a double handicap in a society that is more and more empowered by fast communication. CI is a remedy for deafness, but requires revision surgery every 20 to 25 years, and thus placement should be minimally invasive. Furthermore, failed reimplantation surgery will have more impact on a deafblind person. In this context, we assessed the safety of minimally invasive robotically assisted cochlear implant surgery (RACIS) for the first time in a deafblind patient. Standard pure tone audiometry and speech audiometry were performed in a patient with deafblindness as part of this robotic-assisted CI study before and after surgery. This patient, with an optic atrophy 1 (OPA1) (OMIM#165500) mutation consented to RACIS for the second (contralateral) CI. The applicability and safety of RACIS were evaluated as well as her subjective opinion on her disability. RACIS was uneventful with successful surgical and auditory outcomes in this case of deafblindness due to the OPA1 mutation. RACIS appears to be a safe and beneficial intervention to increase communication skills in the cases of deafblindness due to an OPA1 mutation. The use of RACIS use should be widespread in deafblindness as it minimizes surgical trauma and possible failures.
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23
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Ahnood A, Chambers A, Gelmi A, Yong KT, Kavehei O. Semiconducting electrodes for neural interfacing: a review. Chem Soc Rev 2023; 52:1491-1518. [PMID: 36734845 DOI: 10.1039/d2cs00830k] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
In the past 50 years, the advent of electronic technology to directly interface with neural tissue has transformed the fields of medicine and biology. Devices that restore or even replace impaired bodily functions, such as deep brain stimulators and cochlear implants, have ushered in a new treatment era for previously intractable conditions. Meanwhile, electrodes for recording and stimulating neural activity have allowed researchers to unravel the vast complexities of the human nervous system. Recent advances in semiconducting materials have allowed effective interfaces between electrodes and neuronal tissue through novel devices and structures. Often these are unattainable using conventional metallic electrodes. These have translated into advances in research and treatment. The development of semiconducting materials opens new avenues in neural interfacing. This review considers this emerging class of electrodes and how it can facilitate electrical, optical, and chemical sensing and modulation with high spatial and temporal precision. Semiconducting electrodes have advanced electrically based neural interfacing technologies owing to their unique electrochemical and photo-electrochemical attributes. Key operation modalities, namely sensing and stimulation in electrical, biochemical, and optical domains, are discussed, highlighting their contrast to metallic electrodes from the application and characterization perspective.
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Affiliation(s)
- Arman Ahnood
- School of Engineering, RMIT University, VIC 3000, Australia
| | - Andre Chambers
- School of Physics, University of Melbourne, Melbourne, Victoria 3010, Australia
| | - Amy Gelmi
- School of Science, RMIT University, VIC 3000, Australia
| | - Ken-Tye Yong
- School of Biomedical Engineering, University of Sydney, Sydney, NSW 2006, Australia.,The University of Sydney Nano Institute, Sydney, NSW 2006, Australia.
| | - Omid Kavehei
- School of Biomedical Engineering, University of Sydney, Sydney, NSW 2006, Australia.,The University of Sydney Nano Institute, Sydney, NSW 2006, Australia.
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24
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Ishiyama P, Ishiyama G, Lopez IA, Ishiyama A. Archival Human Temporal Bone: Anatomical and Histopathological Studies of Cochlear Implantation. J Pers Med 2023; 13:352. [PMID: 36836587 PMCID: PMC9959196 DOI: 10.3390/jpm13020352] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2022] [Revised: 02/12/2023] [Accepted: 02/14/2023] [Indexed: 02/22/2023] Open
Abstract
Since being FDA approved in 1984, cochlear implantation has been used successfully to restore hearing in those with severe to profound hearing loss with broader applications including single-sided deafness, the use of hybrid electroacoustic stimulation, and implantation at all extremes of age. Cochlear implants have undergone multiple changes in the design aimed at improving the processing technology, while simultaneously minimizing the surgical trauma and foreign body reaction. The following review examines the human temporal bone studies regarding the anatomy of the human cochlea and how the anatomy relates to cochlear implant design, the factors related to complications after implantation, and the predictors of new tissue formation and osteoneogenesis. Histopathological studies are reviewed which aim to understand the potential implications of the effects of new tissue formation and inflammation following implantation.
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Affiliation(s)
- Paul Ishiyama
- Department of Head and Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Gail Ishiyama
- Department of Neurology, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Ivan A. Lopez
- Department of Head and Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
| | - Akira Ishiyama
- Department of Head and Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA 90095, USA
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25
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Geerardyn A, Zhu M, Wu P, O'Malley J, Nadol JB, Liberman MC, Nakajima HH, Verhaert N, Quesnel AM. Three-dimensional quantification of fibrosis and ossification after cochlear implantation via virtual re-sectioning: Potential implications for residual hearing. Hear Res 2023; 428:108681. [PMID: 36584546 PMCID: PMC10942756 DOI: 10.1016/j.heares.2022.108681] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/14/2022] [Revised: 12/13/2022] [Accepted: 12/18/2022] [Indexed: 12/24/2022]
Abstract
Hearing preservation may be achieved initially in the majority of patients after cochlear implantation, however, a significant proportion of these patients experience delayed hearing loss months or years later. A prior histological report in a case of delayed hearing loss suggested a potential cochlear mechanical origin of this hearing loss due to tissue fibrosis, and older case series highlight the frequent findings of post-implantation fibrosis and neoosteogenesis though without a focus on the impact on residual hearing. Here we present the largest series (N = 20) of 3-dimensionally reconstructed cochleae based on digitally scanned histologic sections from patients who were implanted during their lifetime. All patients were implanted with multichannel electrodes via a cochleostomy or an extended round window insertion. A quantified analysis of intracochlear tissue formation was carried out via virtual re-sectioning orthogonal to the cochlear spiral. Intracochlear tissue formation was present in every case. On average 33% (SD 14%) of the total cochlear volume was occupied by new tissue formation, consisting of 26% (SD 12%) fibrous and 7% (SD 6%) bony tissue. The round window was completely covered by fibro-osseous tissue in 85% of cases and was associated with an obstruction of the cochlear aqueduct in 100%. The basal part of the basilar membrane was at least partially abutted by the electrode or new tissue formation in every case, while the apical region, corresponding with a characteristic frequency of < 500 Hz, appeared normal in 89%. This quantitative analysis shows that after cochlear implantation via extended round window or cochleostomy, intracochlear fibrosis and neoossification are present in all cases at anatomical locations that could impact normal inner ear mechanics.
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Affiliation(s)
- A Geerardyn
- Department of Otolaryngology - Head & Neck Surgery, Harvard Medical School, Boston, MA, USA; Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, USA; ExpORL, Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium
| | - M Zhu
- Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, USA
| | - P Wu
- Department of Otolaryngology - Head & Neck Surgery, Harvard Medical School, Boston, MA, USA; Eaton Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA, USA
| | - J O'Malley
- Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, USA
| | - J B Nadol
- Department of Otolaryngology - Head & Neck Surgery, Harvard Medical School, Boston, MA, USA; Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, USA
| | - M C Liberman
- Department of Otolaryngology - Head & Neck Surgery, Harvard Medical School, Boston, MA, USA; Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, USA; Eaton Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA, USA
| | - H H Nakajima
- Department of Otolaryngology - Head & Neck Surgery, Harvard Medical School, Boston, MA, USA; Eaton Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA, USA
| | - N Verhaert
- ExpORL, Department of Neurosciences, Katholieke Universiteit Leuven, Leuven, Belgium
| | - A M Quesnel
- Department of Otolaryngology - Head & Neck Surgery, Harvard Medical School, Boston, MA, USA; Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA, USA.
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26
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Chen A, Chen D, Lv K, Li G, Pan J, Ma D, Tang J, Zhang H. Zwitterionic Polymer/Polydopamine Coating of Electrode Arrays Reduces Fibrosis and Residual Hearing Loss after Cochlear Implantation. Adv Healthc Mater 2023; 12:e2200807. [PMID: 36177664 DOI: 10.1002/adhm.202200807] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 09/15/2022] [Indexed: 02/03/2023]
Abstract
Since the first surgery 50 years ago, cochlear implantation (CI) is the major treatment for patients with severe sensorineural hearing loss. However, unexpected foreign body reactions (FBRs) after surgery are reported in 90% of CI recipients, resulting in the formation of fibrosis in the cochlea and progressive residual hearing loss. Zwitterion modification is universally used to reduce bio-fouling and suppress FBRs but never for CI. In the present study, a zwitterionic coating is developed, which is composed of poly sulfobetaine methacrylate (PSB) and polydopamine (PDA) for cochlear implants. The PSB-PDA coating shows a series of characters for an ideal anti-FBRs material, including super-hydrophilicity, low protein and cell adsorption, long-term stability, and high biocompatibility. Compared to the uncoated controls, PSB-PDA coating inhibits the activation of macrophages and reduces the release of inflammatory factors (TNF-α, IL-1β, NO) and fibrosis-related factors (TGF-β1, α-SMA, collagen I). PSB-PDA coated electrode arrays suppress fibrosis completely and preserve residual hearing significantly in rat CI models. These results suggest that PSB-PDA coating is a novel strategy for anti-fibrosis to improve the outcomes of CI.
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Affiliation(s)
- Anning Chen
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, 510282, China.,Hearing Research Center, Southern Medical University, Guangzhou, 510282, China
| | - Dongxiu Chen
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, 510282, China.,Hearing Research Center, Southern Medical University, Guangzhou, 510282, China
| | - Kai Lv
- Guangdong Provincial Engineering and Technological Research Center for Drug Carrier Development, Key Laboratory of Biomaterials of Guangdong Higher Education Institutes, Department of Biomedical Engineering, Jinan University, Guangzhou, 510632, China
| | - Guowei Li
- Department of Nuclear Medicine and PET/CT-MRI Center, the First Affiliated Hospital of Jinan University, Guangzhou, 510630, China
| | - Jing Pan
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, 510282, China.,Hearing Research Center, Southern Medical University, Guangzhou, 510282, China
| | - Dong Ma
- Guangdong Provincial Engineering and Technological Research Center for Drug Carrier Development, Key Laboratory of Biomaterials of Guangdong Higher Education Institutes, Department of Biomedical Engineering, Jinan University, Guangzhou, 510632, China
| | - Jie Tang
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, 510282, China.,Hearing Research Center, Southern Medical University, Guangzhou, 510282, China.,Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou, 510515, China.,Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou, 510515, China
| | - Hongzheng Zhang
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou, 510282, China.,Hearing Research Center, Southern Medical University, Guangzhou, 510282, China
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27
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Berger E, Brandes G, Reifenrath J, Lenarz T, Durisin M, Wissel K. In vitro impact of platinum nanoparticles on inner ear related cell culture models. PLoS One 2023; 18:e0284794. [PMID: 37093819 PMCID: PMC10124869 DOI: 10.1371/journal.pone.0284794] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2023] [Accepted: 04/07/2023] [Indexed: 04/25/2023] Open
Abstract
So far, it was supposed that the increase of electrical impedance following cochlear implant (CI) insertion was due to technical defects of the electrode, inflammatory and/or formation of scar tissue along the electrode. However, it was recently reported that corrosion of the platinum electrode contacts may be the reason for high impedances. It could be shown that platinum particles were stripped from the electrode surfaces. Its potential cytotoxic effects within the inner ear remains to be examined. In this study in vitro cell culture models of the mouse organ of Corti cell line (HEI-OC1) and the spiral ganglion (SG) cells derived from the cochleae neonatal rats were used to investigate the effects of the polyvinylpyrrolidone coated platinum nanoparticles (Pt-NPPVP, 3 nm) on cell metabolism, neuronal survival and neurite outgrowth. Our data revealed no decrease of the metabolic activity of the HEI-OC1 cells at Pt-NPPVP concentrations between 50-150 μg/ml. Also, staining with Calcein AM/EthD demonstrated prevalent presence of vital cells. As shown by transmission electron microscopy no Pt-NPPVP could be found at the cell surface or in the cytosol of the HEI-OC1 cells. Similarly, the SG cells exposed to 20-100 μg/ml Pt-NPPVP did not show any reduced survival rate and neurite outgrowth following staining of the neurofilament antigen even at the highest Pt-NPPVP concentration. Although the SG cells were exposed to Pt-NPPVP for further 72 h and 96 h immunocytochemical staining of the glial cells and fibroblasts presented normal cell morphology and growth independently of the cultivation period. Our data indicates that the used Pt-NPPVP do not trigger the cellular uptake and, thus, presumable do not initiate apoptotic pathways in cells of the organ of Corti cell line or the auditory nerve. The protection mechanisms to the Pt-NPPVP interactions remain to be clarified.
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Affiliation(s)
- Elisabeth Berger
- Hannover Medical School, Department of Otorhinolaryngology, Hannover, Germany
- Hannover Medical School, Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany
| | - Gudrun Brandes
- Hannover Medical School, Institute of Neuroanatomy and Cell Biology, Center of Anatomy and Cell Biology, Hannover, Germany
| | - Janin Reifenrath
- Hannover Medical School, Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany
- Hannover Medical School, Clinic for Orthopaedic Surgery, Hannover, Germany
| | - Thomas Lenarz
- Hannover Medical School, Department of Otorhinolaryngology, Hannover, Germany
- Hannover Medical School, Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany
| | - Martin Durisin
- Hannover Medical School, Department of Otorhinolaryngology, Hannover, Germany
- Hannover Medical School, Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany
- University Clinic of Otolaryngology, Head and Neck Surgery, Otto-von-Guericke-University Magdeburg, Magdeburg, Germany
| | - Kirsten Wissel
- Hannover Medical School, Department of Otorhinolaryngology, Hannover, Germany
- Hannover Medical School, Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hannover, Germany
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28
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Jensen MJ, Claussen AD, Higgins T, Vielman-Quevedo R, Mostaert B, Xu L, Kirk J, Hansen MR. Cochlear implant material effects on inflammatory cell function and foreign body response. Hear Res 2022; 426:108597. [PMID: 35963812 PMCID: PMC10875706 DOI: 10.1016/j.heares.2022.108597] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/22/2021] [Revised: 07/08/2022] [Accepted: 08/03/2022] [Indexed: 11/28/2022]
Abstract
OBJECTIVES The objectives of this study were to assess the effects of cochlear implant (CI) biomaterials on the function of macrophages and fibroblasts, two key mediators of the foreign body response (FBR) and to determine how these materials influence fibrous tissue growth and new bone formation within the cochlea. METHODS Macrophages and fibroblasts were cultured on polydimethylsiloxane (PDMS) and platinum substrates and human CI electrodes in vitro. Cell count, cell proliferation, cytokine production, and cell adhesion were measured. CI electrodes were implanted into murine cochleae for three weeks without electrical stimulation. Implanted cochleae were harvested for 3D X-ray microscopy with the CI left in-situ. The location of new bone growth within the scala tympani (ST) with reference to different portions of the implant (PDMS vs platinum) was quantified. RESULTS Cell counts of macrophages and fibroblasts were significantly higher on platinum substrates and platinum contacts of CI electrodes. Fibroblast proliferation was greater on platinum relative to PDMS, and cells grown on platinum formed more/larger focal adhesions. 3D X-ray microscopy showed neo-ossification in the peri‑implant areas of the ST. Volumetric quantification of neo-ossification showed a trend toward greater bone formation adjacent to the platinum electrodes compared to areas opposite or away from the platinum electrode bearing surfaces. CONCLUSIONS Fibrotic reactions are biomaterial specific, as demonstrated by the differences in cell adhesion, proliferation, and fibrosis on platinum and PDMS. The inflammatory reaction to platinum contacts on CI electrodes likely contributes to fibrosis to a greater degree than PDMS, and platinum contacts may influence the deposition of new bone, as demonstrated in the in vivo data. This information can potentially be used to influence the design of future generations of neural prostheses.
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Affiliation(s)
- Megan J Jensen
- Department of Otolaryngology-Head & Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, United States
| | - Alexander D Claussen
- Department of Otolaryngology-Head & Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, United States
| | - Timon Higgins
- Carver College of Medicine, Iowa City, IA, United States
| | - Rene Vielman-Quevedo
- Department of Otolaryngology-Head & Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, United States
| | - Brian Mostaert
- Department of Otolaryngology-Head & Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, United States
| | - Linjing Xu
- Department of Otolaryngology-Head & Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, United States
| | | | - Marlan R Hansen
- Department of Otolaryngology-Head & Neck Surgery, University of Iowa Hospitals and Clinics, Iowa City, IA 52242, United States; Department of Neurosurgery, University of Iowa Hospitals and Clinics, Iowa City, IA, United States.
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Buswinka CJ, Colesa DJ, Swiderski DL, Raphael Y, Pfingst BE. Components of impedance in a cochlear implant animal model with TGFβ1-accelerated fibrosis. Hear Res 2022; 426:108638. [PMID: 36368194 PMCID: PMC10794021 DOI: 10.1016/j.heares.2022.108638] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2022] [Revised: 09/21/2022] [Accepted: 10/18/2022] [Indexed: 11/04/2022]
Abstract
Outcomes of cochlear implantation are likely influenced by the biological state of the cochlea. Fibrosis is a pathological change frequently seen in implanted ears. The goal of this work was to investigate the relationship between fibrosis and impedance. To that end, we employed an animal model of extensive fibrosis and tested whether aspects of impedance differed from controls. Specifically, an adenovirus with a TGF-β1 gene insert (Ad.TGF-β1) was injected into guinea pig scala tympani to elicit rapid onset fibrosis and investigate the relation between fibrosis and impedance. We found a significant correlation between treatment and rate of impedance increase. A physical circuit model of impedance was used to separate the effect of fibrosis from other confounding factors. Supported by preliminary, yet nonconclusive, electron microscopy data, this modeling suggested that deposits on the electrode surface are an important contributor to impedance change over time.
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Affiliation(s)
- Christopher J Buswinka
- Eaton-Peabody Laboratories, Mass Eye and Ear Hospital and Harvard Medical School, Boston MA 02114.
| | - Deborah J Colesa
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Donald L Swiderski
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Yehoash Raphael
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI, 48109, USA
| | - Bryan E Pfingst
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI, 48109, USA
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Claussen AD, Quevedo RV, Kirk JR, Higgins T, Mostaert B, Rahman MT, Oleson J, Hernandez R, Hirose K, Hansen MR. Chronic cochlear implantation with and without electric stimulation in a mouse model induces robust cochlear influx of CX3CR1 +/GFP macrophages. Hear Res 2022; 426:108510. [PMID: 35527124 PMCID: PMC9596618 DOI: 10.1016/j.heares.2022.108510] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/28/2021] [Revised: 03/27/2022] [Accepted: 04/23/2022] [Indexed: 12/16/2022]
Abstract
BACKGROUND Cochlear implantation is an effective auditory rehabilitation strategy for those with profound hearing loss, including those with residual low frequency hearing through use of hybrid cochlear implantation techniques. Post-mortem studies demonstrate the nearly ubiquitous presence of intracochlear fibrosis and neo-ossification following cochlear implantation. Current evidence suggests post-implantation intracochlear fibrosis is associated with delayed loss of residual acoustic hearing in hybrid cochlear implant (CI) recipients and may also negatively influence outcomes in traditional CI recipients. This study examined the contributions of surgical trauma, foreign body response and electric stimulation to intracochlear fibrosis and the innate immune response to cochlear implantation and the hierarchy of these contributions. METHODS Normal hearing CX3CR1+/GFP mice underwent either round window opening (sham), acute CI insertion or chronic CI insertion with no, low- or high-level electric stimulation. Electric stimulation levels were based on neural response telemetry (NRT), beginning post-operative day 7 for 5 h per day. Subjects (n=3 per timepoint) were sacrificed at 4 h, 1,4,7,8,11,14 and 21 days. An unoperated group (n=3) served as controls. Cochleae were harvested at each time-point and prepared for immunohistochemistry with confocal imaging. The images were analyzed to obtain CX3CR1+ macrophage cell number and density in the lateral wall (LW), scala tympani (ST) and Rosenthal's canal (RC). RESULTS A ST peri-implant cellular infiltrate and fibrosis occurred exclusively in the chronically implanted groups starting on day 7 with a concurrent infiltration of CX3CR1+ macrophages not seen in the other groups. CX3CR1+ macrophage infiltration was seen in the LW and RC in all experimental groups within the first week, being most prominent in the 3 chronically implanted groups during the second and third week. CONCLUSIONS The cochlear immune response was most prominent in the presence of chronic cochlear implantation, regardless of electric stimulation level. Further, the development of intracochlear ST fibrosis was dependent on the presence of the indwelling CI foreign body. An innate immune response was evoked by surgical trauma alone (sham and acute CI groups) to a lesser degree. These data suggest that cochlear inflammation and intrascalar fibrosis after cochlear implantation are largely dependent on the presence of a chronic indwelling foreign body and are not critically dependent on electrical stimulation. Also, these data support a role for surgical trauma in inciting the initial innate immune response.
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Affiliation(s)
- Alexander D Claussen
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, United States; Department of Otolaryngology Head and Neck Surgery, University of California San Diego, San Diego, CA 92103, United States.
| | - René Vielman Quevedo
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, United States; Department of Biomedical Sciences, Creighton University, Omaha, NE 68178, United States
| | | | - Timon Higgins
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, United States
| | - Brian Mostaert
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, United States
| | - Muhammad Taifur Rahman
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, United States
| | - Jacob Oleson
- Department of Biostatistics, College of Public Health, University of Iowa, Iowa City, IA 52242, United States
| | - Reyna Hernandez
- Department of Biostatistics, College of Public Health, University of Iowa, Iowa City, IA 52242, United States
| | - Keiko Hirose
- Department of Otolaryngology Head and Neck Surgery, Washington University School of Medicine, St. Louis, MO 63110, United States
| | - Marlan R Hansen
- Department of Otolaryngology Head and Neck Surgery, University of Iowa, Iowa City, IA 52242, United States
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Chen A, Chen Y, Liu S, Ma D, Tang J, Zhang H. Mesoporous silica nanoparticle-modified electrode arrays of cochlear implants for delivery of siRNA-TGFβ1 into the inner ear. Colloids Surf B Biointerfaces 2022; 218:112753. [PMID: 35963142 DOI: 10.1016/j.colsurfb.2022.112753] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/25/2022] [Revised: 06/29/2022] [Accepted: 08/03/2022] [Indexed: 10/16/2022]
Abstract
Cochlear implants (CI) are widely used in patients to restore hearing function. Uncontrolled fibrosis in the cochleae induced by excess secretion of TGFβ1 seriously affects the effectiveness of CIs. siRNA is a potential therapeutic strategy to downregulate TGFβ1 specifically. However, treatment with siRNA in cochleae is difficult due to the poor penetration capability and instability of siRNA and the inaccessibility and vulnerability of cochleae. To address these challenges, we developed amino-functionalized mesoporous silica nanoparticle (MSN-NH2)-modified electrode arrays to deliver siRNA-TGFβ1 into the inner ear. The shape, diameter, pore diameter, and zeta potential of MSN-NH2 were investigated. siRNA loading capability and protective effect of MSN-NH2 were determined by agarose gel electrophoresis assay. The cytotoxicity, cellular uptake assay, and TGFβ1 knockdown efficiency of MSN-NH2 were studied by CCK-8 assay, flow cytometry, and real-time PCR, respectively. MSN-NH2-siTGFβ1 nanoparticles were absorbed into the electrode arrays and worked in the cochleae. MSN-NH2-siTGFβ1-modified CI electrode arrays may be an attractive therapeutic clinical intervention strategy to inhibit cochlear implantation fibrosis.
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Affiliation(s)
- Anning Chen
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China; Hearing Research Center, Southern Medical University, Guangzhou 510282, China
| | - Yaoheng Chen
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China; Hearing Research Center, Southern Medical University, Guangzhou 510282, China
| | - Shixin Liu
- Guangdong Provincial Engineering and Technological Research Center for Drug Carrier Development, Key Laboratory of Biomaterials of Guangdong Higher Education Institutes, Department of Biomedical Engineering, Jinan University, Guangzhou 510632, China
| | - Dong Ma
- Guangdong Provincial Engineering and Technological Research Center for Drug Carrier Development, Key Laboratory of Biomaterials of Guangdong Higher Education Institutes, Department of Biomedical Engineering, Jinan University, Guangzhou 510632, China.
| | - Jie Tang
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China; Hearing Research Center, Southern Medical University, Guangzhou 510282, China; Department of Physiology, School of Basic Medical Sciences, Southern Medical University, Guangzhou 510515, China; Key Laboratory of Mental Health of the Ministry of Education, Southern Medical University, Guangzhou 510515, China.
| | - Hongzheng Zhang
- Department of Otolaryngology Head & Neck Surgery, Zhujiang Hospital, Southern Medical University, Guangzhou 510282, China; Hearing Research Center, Southern Medical University, Guangzhou 510282, China.
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Rahman MT, Chari DA, Ishiyama G, Lopez I, Quesnel AM, Ishiyama A, Nadol JB, Hansen MR. Cochlear implants: Causes, effects and mitigation strategies for the foreign body response and inflammation. Hear Res 2022; 422:108536. [PMID: 35709579 PMCID: PMC9684357 DOI: 10.1016/j.heares.2022.108536] [Citation(s) in RCA: 16] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/20/2021] [Revised: 04/20/2022] [Accepted: 05/23/2022] [Indexed: 12/15/2022]
Abstract
Cochlear implants provide effective auditory rehabilitation for patients with severe to profound sensorineural hearing loss. Recent advances in cochlear implant technology and surgical approaches have enabled a greater number of patients to benefit from this technology, including those with significant residual low frequency acoustic hearing. Nearly all cochleae implanted with a cochlear implant electrode array develop an inflammatory and fibrotic response. This tissue reaction can have deleterious consequences for implant function, residual acoustic hearing, and the development of the next generation of cochlear prosthetics. This article reviews the current understanding of the inflammatory/foreign body response (FBR) after cochlear implant surgery, its impact on clinical outcome, and therapeutic strategies to mitigate this response. Findings from both in human subjects and animal models across a variety of species are highlighted. Electrode array design, surgical techniques, implant materials, and the degree and type of electrical stimulation are some critical factors that affect the FBR and inflammation. Modification of these factors and various anti-inflammatory pharmacological interventions have been shown to mitigate the inflammatory/FBR response. Ongoing and future approaches that seek to limit surgical trauma and curb the FBR to the implanted biomaterials of the electrode array are discussed. A better understanding of the anatomical, cellular and molecular basis of the inflammatory/FBR response after cochlear implantation has the potential to improve the outcome of current cochlear implants and also facilitate the development of the next generation of neural prostheses.
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Affiliation(s)
- Muhammad T Rahman
- Department of Otolaryngology-Head & Neck Surgery, University of Iowa, Iowa City, IA, USA
| | - Divya A Chari
- Department of Otolaryngology-Head & Neck Surgery, Harvard University, Boston, MA, USA
| | - Gail Ishiyama
- Department of Head & Neck Surgery, University of California Los Angeles, LA, USA
| | - Ivan Lopez
- Department of Head & Neck Surgery, University of California Los Angeles, LA, USA
| | - Alicia M Quesnel
- Department of Otolaryngology-Head & Neck Surgery, Harvard University, Boston, MA, USA
| | - Akira Ishiyama
- Department of Head & Neck Surgery, University of California Los Angeles, LA, USA
| | - Joseph B Nadol
- Department of Otolaryngology-Head & Neck Surgery, Harvard University, Boston, MA, USA
| | - Marlan R Hansen
- Department of Otolaryngology-Head & Neck Surgery, University of Iowa, Iowa City, IA, USA.
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Wimmer W, Sclabas L, Caversaccio M, Weder S. Cochlear Implant Electrode Impedance as Potential Biomarker for Residual Hearing. Front Neurol 2022; 13:886171. [PMID: 35832176 PMCID: PMC9271767 DOI: 10.3389/fneur.2022.886171] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 05/31/2022] [Indexed: 11/13/2022] Open
Abstract
Introduction and ObjectivesAmong cochlear implant candidates, an increasing number of patients are presenting with residual acoustic hearing. To monitor the postoperative course of structural and functional preservation of the cochlea, a reliable objective biomarker would be desirable. Recently, impedance telemetry has gained increasing attention in this field. The aim of this study was to investigate the postoperative course of the residual acoustic hearing and clinical impedance in patients with long electrode arrays and to explore the applicability of impedance telemetry for monitoring residual hearing.MethodsWe retrospectively analyzed records of 42 cochlear implant recipients with residual hearing covering a median postoperative follow-up of 25 months with repeated simultaneous pure tone audiometry and impedance telemetry. We used a linear mixed-effects model to estimate the relation between clinical electrode impedance and residual hearing. Besides the clinical impedance, the follow-up time, side of implantation, gender, and age at implantation were included as fixed effects. An interaction term between impedance and follow-up time, as well as subject-level random intercepts and slopes, were included.ResultsLoss of residual hearing occurred either during surgery or within the first 6 post-operative months. Electrode contacts inserted further apically (i.e., deeper) had higher impedances, independent of residual hearing. The highest impedances were measured 1 month postoperatively and gradually decreased over time. Basal electrodes were more likely to maintain higher impedance. Follow-up time was significantly associated with residual hearing. Regardless of the time, we found that a 1 kΩ increase in clinical impedance was associated with a 4.4 dB deterioration of residual hearing (p < 0.001).ConclusionPure tone audiometry is the current gold standard for monitoring postoperative residual hearing. However, the association of clinical impedances with residual hearing thresholds found in our study could potentially be exploited for objective monitoring using impedance telemetry. Further analysis including near-field related impedance components could be performed for improved specificity to local immune responses.
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Affiliation(s)
- Wilhelm Wimmer
- Hearing Research Laboratory, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
- Department of ENT—Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
- *Correspondence: Wilhelm Wimmer
| | - Luca Sclabas
- Department of ENT—Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Marco Caversaccio
- Hearing Research Laboratory, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
- Department of ENT—Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
| | - Stefan Weder
- Hearing Research Laboratory, ARTORG Center for Biomedical Engineering Research, University of Bern, Bern, Switzerland
- Department of ENT—Head and Neck Surgery, Inselspital, Bern University Hospital, University of Bern, Bern, Switzerland
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Okayasu T, O’Malley JT, Nadol JB. Prevalence of Macrophages Within the Cochlear Vessels Following Cochlear Implantation in the Human: An Immunohistopathological Study Using Anti-Iba1 Antibody. Otol Neurotol 2021; 42:e1470-e1477. [PMID: 34325451 PMCID: PMC8595581 DOI: 10.1097/mao.0000000000003312] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
HYPOTHESIS The prevalence of monocyte-derived macrophages within cochlear vessels may increase following cochlear implantation. BACKGROUND Recently, we reported an increase in the number of ionized calcium-binding adaptor molecule 1 (Iba1)-positive macrophages in selected cochlear sites such as the osseous spiral lamina and Rosenthal's canal following cochlear implantation. Activation of the immune system induces the recruitment of monocyte-derived macrophages. The prevalence of monocyte-derived macrophages within cochlear vessels may increase following cochlear implantation. However, the delivery system of macrophages to the human cochlea is incompletely understood. METHODS The prevalence of macrophages and monocytes within cochlear blood vessels in 10 human subjects who had undergone unilateral cochlear implantation was studied by light microscopy using anti-Iba1 immunostaining. The densities of Iba1-positve monocytes per area of lumen of cochlear vessels in the sections near the round window in implanted ears were compared with the contralateral unimplanted ears. The correlation between the densities of Iba1-positve monocytes and the duration (months after the cochlear implantation) was also evaluated. RESULTS The prevalence of Iba1-positive macrophages/monocytes in vessels near the round window in implanted ears (mean 26%, median 21%) was greater than in opposite unimplanted ears (mean 5.2%, median 2.5%: p < 0.01). The density of Iba1-positive monocytes in implanted ears (mean 32, median 16 cells/105 μm2) tended to be greater than that in unimplanted ears (mean 6.6, median 0.93 cells/105 μm2: p = 0.08). The density of Iba1-positive monocytes was significantly correlated with duration of implantation but not in the unimplanted ears. CONCLUSION An increase in prevalence of Iba1-positive macrophages/monocytes within cochlear blood vessels after cochlear implantation was demonstrated. These findings suggest a delivery system of Iba1-positive macrophages through cochlear vessels in human that is ongoing for long duration.
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Affiliation(s)
- Tadao Okayasu
- Otopathology Laboratory, Department of Otolaryngology-Head and Neck Surgery, Massachusetts Eye and Ear, 243 Charles Street, Boston, MA 02114 USA
- Department of Otolaryngology, Harvard Medical School-Head and Neck Surgery, 243 Charles Street, Boston, MA 02114 USA
- Department of Otolaryngology-Head and Neck Surgery, Nara Medical University, 840 Shijo-cho, Kashihara city, Nara 634-8522, Japan
| | - Jennifer T. O’Malley
- Otopathology Laboratory, Department of Otolaryngology-Head and Neck Surgery, Massachusetts Eye and Ear, 243 Charles Street, Boston, MA 02114 USA
| | - Joseph B. Nadol
- Otopathology Laboratory, Department of Otolaryngology-Head and Neck Surgery, Massachusetts Eye and Ear, 243 Charles Street, Boston, MA 02114 USA
- Department of Otolaryngology, Harvard Medical School-Head and Neck Surgery, 243 Charles Street, Boston, MA 02114 USA
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Whitaker R, Hernaez-Estrada B, Hernandez RM, Santos-Vizcaino E, Spiller KL. Immunomodulatory Biomaterials for Tissue Repair. Chem Rev 2021; 121:11305-11335. [PMID: 34415742 DOI: 10.1021/acs.chemrev.0c00895] [Citation(s) in RCA: 109] [Impact Index Per Article: 36.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
All implanted biomaterials are targets of the host's immune system. While the host inflammatory response was once considered a detrimental force to be blunted or avoided, in recent years, it has become a powerful force to be leveraged to augment biomaterial-tissue integration and tissue repair. In this review, we will discuss the major immune cells that mediate the inflammatory response to biomaterials, with a focus on how biomaterials can be designed to modulate immune cell behavior to promote biomaterial-tissue integration. In particular, the intentional activation of monocytes and macrophages with controlled timing, and modulation of their interactions with other cell types involved in wound healing, have emerged as key strategies to improve biomaterial efficacy. To this end, careful design of biomaterial structure and controlled release of immunomodulators can be employed to manipulate macrophage phenotype for the maximization of the wound healing response with enhanced tissue integration and repair, as opposed to a typical foreign body response characterized by fibrous encapsulation and implant isolation. We discuss current challenges in the clinical translation of immunomodulatory biomaterials, such as limitations in the use of in vitro studies and animal models to model the human immune response. Finally, we describe future directions and opportunities for understanding and controlling the biomaterial-immune system interface, including the application of new imaging tools, new animal models, the discovery of new cellular targets, and novel techniques for in situ immune cell reprogramming.
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Affiliation(s)
- Ricardo Whitaker
- School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, Pennsylvania 19104, United States
| | - Beatriz Hernaez-Estrada
- School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, Pennsylvania 19104, United States.,NanoBioCel Group, Laboratory of Pharmaceutics, School of Pharmacy, University of the Basque Country (UPV/EHU), Vitoria-Gasteiz 01006, Spain
| | - Rosa Maria Hernandez
- NanoBioCel Group, Laboratory of Pharmaceutics, School of Pharmacy, University of the Basque Country (UPV/EHU), Vitoria-Gasteiz 01006, Spain.,Biomedical Research Networking Centre in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Vitoria-Gasteiz 01006, Spain
| | - Edorta Santos-Vizcaino
- NanoBioCel Group, Laboratory of Pharmaceutics, School of Pharmacy, University of the Basque Country (UPV/EHU), Vitoria-Gasteiz 01006, Spain.,Biomedical Research Networking Centre in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Vitoria-Gasteiz 01006, Spain
| | - Kara L Spiller
- School of Biomedical Engineering, Science, and Health Systems, Drexel University, Philadelphia, Pennsylvania 19104, United States
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Hough K, Verschuur CA, Cunningham C, Newman TA. Macrophages in the cochlea; an immunological link between risk factors and progressive hearing loss. Glia 2021; 70:219-238. [PMID: 34536249 DOI: 10.1002/glia.24095] [Citation(s) in RCA: 28] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2021] [Revised: 09/08/2021] [Accepted: 09/09/2021] [Indexed: 02/06/2023]
Abstract
Macrophages are abundant in the cochlea; however, their role in hearing loss is not well understood. Insults to the cochlea, such as noise or insertion of a cochlear implant, cause an inflammatory response, which includes activation of tissue-resident macrophages. Activation is characterized by changes in macrophage morphology, mediator expression, and distribution. Evidence from other organs shows activated macrophages can become primed, whereby subsequent insults cause an elevated inflammatory response. Primed macrophages in brain pathologies respond to circulating inflammatory mediators by disproportionate synthesis of inflammatory mediators. This signaling occurs behind an intact blood-brain barrier, similar to the blood-labyrinth barrier in the cochlea. Local tissue damage can occur as the result of mediator release by activated macrophages. Damage is typically localized; however, if it is to structures with limited ability to repair, such as neurons or hair cells within the cochlea, it is feasible that this contributes to the progressive loss of function seen in hearing loss. We propose that macrophages in the cochlea link risk factors and hearing loss. Injury to the cochlea causes local macrophage activation that typically resolves. However, in susceptible individuals, some macrophages enter a primed state. Once primed, these macrophages can be further activated, as a consequence of circulating inflammatory molecules associated with common co-morbidities. Hypothetically, this would lead to further cochlear damage and loss of hearing. We review the evidence for the role of tissue-resident macrophages in the cochlea and propose that cochlear macrophages contribute to the trajectory of hearing loss and warrant further study.
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Affiliation(s)
- Kate Hough
- Faculty of Engineering and Physical Sciences, University of Southampton, Southampton, UK
| | - Carl A Verschuur
- Faculty of Engineering and Physical Sciences, Auditory Implant Centre, University of Southampton, Southampton, UK
| | - Colm Cunningham
- School of Biochemistry & Immunology, Trinity Biomedical Sciences Institute & Trinity College Institute of Neuroscience (TCIN), Dublin, Ireland
| | - Tracey A Newman
- Clinical and Experimental Sciences, Faculty of Medicine, IfLS, University of Southampton, Southampton, UK
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Bennion DM, Horne R, Peel A, Reineke P, Henslee A, Kaufmann C, Guymon CA, Hansen MR. Zwitterionic Photografted Coatings of Cochlear Implant Biomaterials Reduce Friction and Insertion Forces. Otol Neurotol 2021; 42:1476-1483. [PMID: 34310554 DOI: 10.1097/mao.0000000000003288] [Citation(s) in RCA: 11] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
HYPOTHESIS Application of photografted zwitterionic coatings to cochlear implant (CI) biomaterials will reduce friction and insertion forces. BACKGROUND Strategies to minimize intracochlear trauma during implantation of an electrode array are critical to optimize outcomes including preservation of residual hearing. To this end, advances in thin-film zwitterionic hydrogel coatings on relevant biomaterials may show promise, in addition to the potential of these materials for decreasing the intracochlear foreign body response. METHODS Using a recently designed one-step process, thin-film coatings derived from zwitterionic sulfobetaine methacrylate (SBMA) were photopolymerized and photografted to the surface of polydimethylsiloxane (PDMS, silastic) samples and also to CI arrays from two manufacturers. Fluorescein staining and scanning electron microscopy with energy-dispersive X-ray spectroscopy verified and characterized the coatings. Tribometry was used to measure the coefficient of friction between uncoated and coated PDMS and synthetic and biological tissues. Force transducer measurements were obtained during insertion of uncoated (n = 9) and coated (n = 9) CI electrode arrays into human cadaveric cochleae. RESULTS SBMA thin-film coating of PDMS resulted in >90% reduction in frictional coefficients with steel, ceramic, and dermal tissue from guinea pigs (p < 0.0001). We employed a novel method for applying covalently bonded, durable, and uniform coating in geographically selective areas at the electrode array portion of the implant. Image analysis confirmed uniform coating of PDMS systems and the CI electrode arrays with SBMA polymer films. During insertion of electrode arrays into human cadaveric cochleae, SBMA coatings reduced maximum force by ∼40% during insertion (p < 0.001), as well as decreasing force variability and the overall work of insertion. CONCLUSION Thin-film SBMA photografted coatings on PDMS and electrode arrays significantly reduce frictional coefficients and insertional forces in cadaveric cochleae. These encouraging findings support that thin-film zwitterionic coating of CI electrode arrays may potentially reduce insertional trauma and thereby promote improved hearing and other long-term outcomes.
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Affiliation(s)
- Douglas M Bennion
- Department of Otolaryngology-Head and Neck Surgery Department of Chemical and Biochemical Engineering, University of Iowa iotaMotion, Inc, Iowa City, Iowa
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Lin C, Ekblad-Nordberg Å, Michaëlsson J, Götherström C, Hsu CC, Ye H, Johansson J, Rising A, Sundström E, Åkesson E. In Vitro Study of Human Immune Responses to Hyaluronic Acid Hydrogels, Recombinant Spidroins and Human Neural Progenitor Cells of Relevance to Spinal Cord Injury Repair. Cells 2021; 10:1713. [PMID: 34359882 PMCID: PMC8303367 DOI: 10.3390/cells10071713] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2021] [Revised: 06/28/2021] [Accepted: 06/30/2021] [Indexed: 02/07/2023] Open
Abstract
Scaffolds of recombinant spider silk protein (spidroin) and hyaluronic acid (HA) hydrogel hold promise in combination with cell therapy for spinal cord injury. However, little is known concerning the human immune response to these biomaterials and grafted human neural stem/progenitor cells (hNPCs). Here, we analyzed short- and long-term in vitro activation of immune cells in human peripheral blood mononuclear cells (hPBMCs) cultured with/without recombinant spidroins, HA hydrogels, and/or allogeneic hNPCs to assess potential host-donor interactions. Viability, proliferation and phenotype of hPBMCs were analyzed using NucleoCounter and flow cytometry. hPBMC viability was confirmed after exposure to the different biomaterials. Short-term (15 h) co-cultures of hPBMCs with spidroins, but not with HA hydrogel, resulted in a significant increase in the proportion of activated CD69+ CD4+ T cells, CD8+ T cells, B cells and NK cells, which likely was caused by residual endotoxins from the Escherichia coli expression system. The observed spidroin-induced hPBMC activation was not altered by hNPCs. It is resource-effective to evaluate human compatibility of novel biomaterials early in development of the production process to, when necessary, make alterations to minimize rejection risk. Here, we present a method to evaluate biomaterials and hPBMC compatibility in conjunction with allogeneic human cells.
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Affiliation(s)
- Chenhong Lin
- Division of Neurogeriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, SE-171 64 Stockholm, Sweden;
| | - Åsa Ekblad-Nordberg
- Division of Obstetrics and Gynecology, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, SE-141 52 Stockholm, Sweden; (Å.E.-N.); (C.G.)
| | - Jakob Michaëlsson
- Center for Infectious Medicine, Department of Medicine Huddinge, Karolinska Institutet, SE-141 86 Stockholm, Sweden;
| | - Cecilia Götherström
- Division of Obstetrics and Gynecology, Department of Clinical Science, Intervention and Technology, Karolinska Institutet, SE-141 52 Stockholm, Sweden; (Å.E.-N.); (C.G.)
| | - Chia-Chen Hsu
- Department of Engineering Science, Institute of Biomedical Engineering, University of Oxford, Oxford OX3 7DQ, UK; (C.-C.H.); (H.Y.)
| | - Hua Ye
- Department of Engineering Science, Institute of Biomedical Engineering, University of Oxford, Oxford OX3 7DQ, UK; (C.-C.H.); (H.Y.)
| | - Jan Johansson
- Department of Biosciences and Nutrition, Karolinska Institutet, SE-141 83 Stockholm, Sweden; (J.J.); (A.R.)
| | - Anna Rising
- Department of Biosciences and Nutrition, Karolinska Institutet, SE-141 83 Stockholm, Sweden; (J.J.); (A.R.)
- Department of Anatomy, Physiology and Biochemistry, Swedish University of Agricultural Sciences, SE-750 07 Uppsala, Sweden
| | - Erik Sundström
- Division of Neurogeriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, SE-171 64 Stockholm, Sweden;
| | - Elisabet Åkesson
- Division of Neurogeriatrics, Department of Neurobiology, Care Sciences and Society, Karolinska Institutet, SE-171 64 Stockholm, Sweden;
- The R&D Unit, Stockholms Sjukhem, SE-112 19 Stockholm, Sweden
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Kim S, Han G, Hwang D, Won D, Shin Y, Kim C, Kang JM, Park J, Jung H, Park W, Yun J. Design and Usability Evaluations of a 3D-Printed Implantable Drug Delivery Device for Acute Liver Failure in Preclinical Settings. Adv Healthc Mater 2021; 10:e2100497. [PMID: 34160141 DOI: 10.1002/adhm.202100497] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/15/2021] [Revised: 05/18/2021] [Indexed: 12/11/2022]
Abstract
Acute liver failure (ALF) requiring liver transplantation is a disease that occurs due to rapid hepatocellular dysfunction. As liver transplantation has various limitations, including donor scarcity, high cost, and immuno-incompatibility, continuous local delivery of biopharmaceuticals to the liver tissue can be a promising ALF treatment option. Here, the in vivo safety and usability of a 3D-printed implantable drug delivery device for effective ALF treatment is evaluated. The implantable reservoir consists of a 3D-printed container and a semipermeable membrane for repeated administrations of drugs, specifically to the liver tissue. The physical stability and function of the 3D-printed reservoir are confirmed by the mechanical properties and in vitro drug release test, respectively. In mice implanted with the reservoir system, mortality, weight changes, clinical signs, hematological and serum biochemical changes, and organ weight changes are not observed, suggesting no foreign body reaction. The usability of the reservoir system is further evaluated using an ALF model of 70% hepatectomized mice treated with N-acetylcysteine through the system, showing cell-specific regeneration and significant liver injury alleviation. Overall, the 3D-printed reservoir system is safe for studying the therapeutic potential of ALF treatment, and it can be used for the delivery of various active pharmaceutical ingredients.
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Affiliation(s)
- Shin‐Young Kim
- Department of Biotechnology The Catholic University of Korea 43 Jibong‐ro Bucheon‐Si Gyeonggi‐do 14662 Republic of Korea
| | - Ginam Han
- Department of Biotechnology The Catholic University of Korea 43 Jibong‐ro Bucheon‐Si Gyeonggi‐do 14662 Republic of Korea
- Department of Biomedical‐Chemical Engineering The Catholic University of Korea 43 Jibong‐ro Bucheon‐Si Gyeonggi‐do 14662 Republic of Korea
| | - Da‐Bin Hwang
- Department of Biotechnology The Catholic University of Korea 43 Jibong‐ro Bucheon‐Si Gyeonggi‐do 14662 Republic of Korea
| | - Dong‐Hoon Won
- Department of Biotechnology The Catholic University of Korea 43 Jibong‐ro Bucheon‐Si Gyeonggi‐do 14662 Republic of Korea
| | - Yoo‐Sub Shin
- Department of Biotechnology The Catholic University of Korea 43 Jibong‐ro Bucheon‐Si Gyeonggi‐do 14662 Republic of Korea
| | - Changuk Kim
- Department of Biotechnology The Catholic University of Korea 43 Jibong‐ro Bucheon‐Si Gyeonggi‐do 14662 Republic of Korea
| | - Jeon Min Kang
- Biomedical Engineering Research Center Asan Institute for Life Sciences Asan Medical Center 88 Olympic‐ro 43‐gil Songpa‐gu Seoul 05505 Republic of Korea
| | - Jung‐Hoon Park
- Biomedical Engineering Research Center Asan Institute for Life Sciences Asan Medical Center 88 Olympic‐ro 43‐gil Songpa‐gu Seoul 05505 Republic of Korea
| | - Hyun‐Do Jung
- Department of Biotechnology The Catholic University of Korea 43 Jibong‐ro Bucheon‐Si Gyeonggi‐do 14662 Republic of Korea
- Department of Biomedical‐Chemical Engineering The Catholic University of Korea 43 Jibong‐ro Bucheon‐Si Gyeonggi‐do 14662 Republic of Korea
| | - Wooram Park
- Department of Biotechnology The Catholic University of Korea 43 Jibong‐ro Bucheon‐Si Gyeonggi‐do 14662 Republic of Korea
- Department of Biomedical‐Chemical Engineering The Catholic University of Korea 43 Jibong‐ro Bucheon‐Si Gyeonggi‐do 14662 Republic of Korea
| | - Jun‐Won Yun
- Department of Biotechnology The Catholic University of Korea 43 Jibong‐ro Bucheon‐Si Gyeonggi‐do 14662 Republic of Korea
- Department of Medical and Biological Sciences The Catholic University of Korea 43 Jibong‐ro Bucheon‐Si Gyeonggi‐do 14662 Republic of Korea
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Hough K, Sanderson A, Grasmeder M, Mitchell T, Verschuur CA, Newman TA. Inflammation at the Tissue-Electrode Interface in a Case of Rapid Deterioration in Hearing Performance Leading to Explant After Cochlear Implantation. Otol Neurotol 2021; 42:e445-e450. [PMID: 33710995 DOI: 10.1097/mao.0000000000003014] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
OBJECTIVE The reasons for soft failure after cochlear implantation require investigation. This study proposes a method to study and characterize the tissue response to the array in a case of soft failure in a person undergoing reimplantation. CASE The woman in her 50s, with an underlying autoimmune condition, received a cochlear implant using hearing preservation technique after developing profound hearing loss more than 2 kHz with a moderate loss of less than 500 Hz over a 10-year period. The case was identified as a soft failure due to deteriorating performance, discomfort, and migration over the 10 months after implantation. Impedance telemetry, speech perception measures, and audiometric thresholds are described. At explantation there was evidence of fibrosis. INTERVENTIONS To use histology and immunohistochemistry to determine the cellular response of the tissue associated with the electrode array at time of explantation. MAIN OUTCOME MEASURES Identification of the cell types, regional variations, and inflammatory marker expression in the fibrotic tissue associated with the array. RESULTS Neutrophils and eosinophils were identified, along with a variable pattern of collagen deposition. CD68 and CD163-positive macrophages and T cells were variably distributed through the tissue and interleukin-1 beta and vascular endothelial growth factor receptor-2 expression was identified. CONCLUSIONS The expression profile is evidence of active inflammation in the tissue despite the time since implantation. This study is the first to characterize the tissue response to the array in a person undergoing reimplantation, and who can be followed to determine the individual response to arrays. It establishes that the investigation of explanted devices after soft-failure is feasible.
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Affiliation(s)
- Kate Hough
- Faculty of Engineering and Physical Sciences
| | | | - Mary Grasmeder
- Faculty of Engineering and Physical Sciences, Auditory Implant Centre
| | - Tim Mitchell
- Faculty of Engineering and Physical Sciences, Auditory Implant Centre
| | - Carl A Verschuur
- Faculty of Engineering and Physical Sciences, Auditory Implant Centre
| | - Tracey A Newman
- Clinical and Experimental Sciences, Faculty of Medicine, Institute for Life Sciences, University of Southampton, Southampton, UK
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Noonan KY, Lopez IA, Ishiyama G, Ishiyama A. Immune Response of Macrophage Population to Cochlear Implantation: Cochlea Immune Cells. Otol Neurotol 2021; 41:1288-1295. [PMID: 32925862 DOI: 10.1097/mao.0000000000002764] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
HYPOTHESIS The presence and distribution of ionized calcium binding adaptor 1 and CD68 macrophages in the human cochlea is altered in cochlear implantation (CI) compared with the normative or nonimplanted cochlea. BACKGROUND It has been hypothesized that CI induces an immunological response in macrophages leading to implant failure or reduced hearing. Macrophages are resident immune cells in human cochlea and have been shown to phagocytize implant material. In animal models, macrophage populations increase with surgical stress and with the introduction of a foreign body. However, the function and response of inner ear macrophages to CI are only beginning to be understood. This study seeks to investigate the inflammatory response to CI by comparing cochlear macrophages in implanted and nonimplanted human temporal bones. METHODS Nineteen temporal bones from nine implanted ears, seven contralateral controls, and three normal control ears were evaluated for the presence and distribution of CD68 and Iba1 expressing positive macrophages. RESULTS Three types of macrophage populations were detected 1) CD68 positive macrophages, 2) Iba1 positive macrophages, and 3) CD68 and Iba1 colocalizing macrophages. Macrophage distribution was ubiquitous: the stria vascularis, Rosenthal canal, and the mid-modiolus intermingled in the spiral ganglia. Iba1 and CD68 macrophages were found in the CI and non-CI contralateral and normal human cochlea. Most ionized calcium binding adaptor 1 expressing macrophages were ramified/amoeboid cells, while CD68 expressing macrophages were round shaped with foamy appearance in some areas. In the CI cochlea, both types of macrophages were detected in the fibrous sheath surrounding the CI path and within fibrotic areas within the scala tympani and the scala vestibuli in the case of CI translocation. In four cases, the density of macrophages was unchanged in the CI compared with the contralateral nonimplanted side, and in three cases, there was an increased number of macrophages in the implanted CI side compared with the nonimplanted side. CONCLUSION Multiple populations of macrophages exist within the cochlea which are present at baseline and in response to trauma from CI. These results further support evidence for a macrophage response to cochlear implantation. Further studies are indicated to evaluate whether these macrophages have a beneficial, detrimental, or a mixed effect in CI patients.
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Affiliation(s)
| | - Ivan A Lopez
- University of California Los Angeles, Los Angeles, California
| | - Gail Ishiyama
- University of California Los Angeles, Los Angeles, California
| | - Akira Ishiyama
- University of California Los Angeles, Los Angeles, California
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The Distribution and Prevalence of Macrophages in the Cochlea Following Cochlear Implantation in the Human: An Immunohistochemical Study Using Anti-Iba1 Antibody. Otol Neurotol 2021; 41:e304-e316. [PMID: 31821256 DOI: 10.1097/mao.0000000000002495] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
HYPOTHESIS Cochlear implantation may cause an increase in the number of macrophages in the human cochlea similar to previous findings in the vestibular endorgans. BACKGROUND Macrophages play a key role in both an inflammatory response and homeostatic maintenance. Recently, an increase in the prevalence of macrophages was demonstrated in the human vestibular endorgans after implantation. However, the prevalence of macrophages in the cochlea after implantation is unclear. The aim of this study was to compare the distribution and prevalence of macrophages in implanted human cochleae and the contralateral unimplanted ears. METHODS The prevalence of macrophages in the cochlea in 10 human subjects who had undergone unilateral cochlear implantation was studied by light microscopy using anti-Iba1 immunostaining. The densities of macrophages in the osseous spiral lamina (OSL) and Rosenthal's canal (RC) in implanted cochleae were compared with the contralateral unimplanted ears. The distribution of macrophage morphology (amoeboid, transitional, and ramified) was also compared. RESULTS There were activated and phagocytosing macrophages within the fibrotic sheath surrounding the electrode track and within fibrous tissue with lymphocytic infiltration in implanted ears. The densities of macrophages in OSL and RC in implanted ears were significantly greater than in unimplanted ears in some areas. There was also a difference in the prevalence of macrophage phenotype between the OSL and RC. CONCLUSION An increase in the density of macrophages in the cochlea after cochlear implantation was demonstrated. Both phagocytosis and anti-inflammatory activity of macrophages were suggested by the distribution and prevalence of macrophages in the implanted cochlea.
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Shepherd RK, Carter PM, Dalrymple AN, Enke YL, Wise AK, Nguyen T, Firth J, Thompson A, Fallon JB. Platinum dissolution and tissue response following long-term electrical stimulation at high charge densities. J Neural Eng 2021; 18:10.1088/1741-2552/abe5ba. [PMID: 33578409 PMCID: PMC8711780 DOI: 10.1088/1741-2552/abe5ba] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Accepted: 02/12/2021] [Indexed: 11/11/2022]
Abstract
Objective. Established guidelines for safe levels of electrical stimulation for neural prostheses are based on a limited range of the stimulus parameters used clinically. Recent studies have reported particulate platinum (Pt) associated with long-term clinical use of these devices, highlighting the need for more carefully defined safety limits. We previously reported no adverse effects of Pt corrosion products in the cochleae of guinea pigs following 4 weeks of electrical stimulation using charge densities far greater than the published safe limits for cochlear implants. The present study examines the histopathological effects of Pt within the cochlea following continuous stimulation at a charge density well above the defined safe limits for periods up to 6 months.Approach. Six cats were bilaterally implanted with Pt electrode arrays and unilaterally stimulated using charge balanced current pulses at a charge density of 267μC cm-2phase-1using a tripolar electrode configuration. Electrochemical measurements were made throughout the implant duration and evoked potentials recorded at the outset and on completion of the stimulation program. Cochleae were examined histologically for particulate Pt, tissue response, and auditory nerve survival; electrodes were examined for surface corrosion; and cochlea, brain, kidney, and liver tissue analysed for trace levels of Pt.Main results. Chronic stimulation resulted in both a significant increase in tissue response and particulate Pt within the tissue capsule surrounding the electrode array compared with implanted, unstimulated control cochleae. Importantly, there was no stimulus-induced loss of auditory neurons (ANs) or increase in evoked potential thresholds. Stimulated electrodes were significantly more corroded compared with unstimulated electrodes. Trace analysis revealed Pt in both stimulated and control cochleae although significantly greater levels were detected within stimulated cochleae. There was no evidence of Pt in brain or liver; however, trace levels of Pt were recorded in the kidneys of two animals. Finally, increased charge storage capacity and charge injection limit reflected the more extensive electrode corrosion associated with stimulated electrodes.Significance. Long-term electrical stimulation of Pt electrodes at a charge density well above existing safety limits and nearly an order of magnitude higher than levels used clinically, does not adversely affect the AN population or reduce neural function, despite a stimulus-induced tissue response and the accumulation of Pt corrosion product. The mechanism resulting in Pt within the unstimulated cochlea is unclear, while the level of Pt observed systemically following stimulation at these very high charge densities does not appear to be of clinical significance.
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Affiliation(s)
- Robert K Shepherd
- Bionics Institute, St Vincent's Hospital, Melbourne, Australia
- Medical Bionics Department, University of Melbourne, Melbourne, Australia
| | | | - Ashley N Dalrymple
- Bionics Institute, St Vincent's Hospital, Melbourne, Australia
- Department of Mechanical Engineering, Carnegie Mellon University, Pittsburgh, PA, United States of America
| | | | - Andrew K Wise
- Bionics Institute, St Vincent's Hospital, Melbourne, Australia
- Medical Bionics Department, University of Melbourne, Melbourne, Australia
| | - Trung Nguyen
- Bionics Institute, St Vincent's Hospital, Melbourne, Australia
| | - James Firth
- Bionics Institute, St Vincent's Hospital, Melbourne, Australia
| | - Alex Thompson
- Bionics Institute, St Vincent's Hospital, Melbourne, Australia
| | - James B Fallon
- Bionics Institute, St Vincent's Hospital, Melbourne, Australia
- Medical Bionics Department, University of Melbourne, Melbourne, Australia
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Beta-Titanium Alloy Covered by Ferroelectric Coating–Physicochemical Properties and Human Osteoblast-Like Cell Response. COATINGS 2021. [DOI: 10.3390/coatings11020210] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
Beta-titanium alloys are promising materials for bone implants due to their advantageous mechanical properties. For enhancing the interaction of bone cells with this perspective material, we developed a ferroelectric barium titanate (BaTiO3) coating on a Ti39Nb alloy by hydrothermal synthesis. This coating was analyzed by scanning electron and Raman microscopy, X-ray diffraction, piezoresponse force microscopy, X-ray photoelectron spectroscopy, nanoindentation, and roughness measurement. Leaching experiments in a saline solution revealed that Ba is released from the coating. A progressive decrease of Ba concentration in the material was also found after 1, 3, and 7 days of cultivation of human osteoblast-like Saos-2 cells. On day 1, the Saos-2 cells adhered on the BaTiO3 film in higher initial numbers than on the bare alloy, but they were less spread, and their initial proliferation rate was slower. These cells also contained a lower amount of beta1-integrins and vinculin, i.e., molecules involved in cell adhesion, and produced a lower amount of collagen I. This cell behavior was attributed to a higher surface roughness of BaTiO3 film rather than to its potential cytotoxicity, because the cell viability on this film was very high, reaching almost 99%. The amount of alkaline phosphatase, an enzyme involved in bone matrix mineralization, was similar in cells on the BaTiO3-coated and uncoated alloy, and on day 7, the cells on BaTiO3 film attained a higher final cell population density. These results indicate that after some improvements, particularly in its roughness and stability, the hydrothermal ferroelectric BaTiO3 film could be promising coating for improved osseointegration of bone implants.
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Perin P, Marino F, Varela-Nieto I, Szczepek AJ. Editorial: Neuroimmunology of the Inner Ear. Front Neurol 2021; 12:635359. [PMID: 33633679 PMCID: PMC7899967 DOI: 10.3389/fneur.2021.635359] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 01/07/2021] [Indexed: 12/20/2022] Open
Affiliation(s)
- Paola Perin
- Department of Brain and Behavioural Sciences, University of Pavia, Pavia, Italy
| | - Franca Marino
- Center of Research in Medical Pharmacology University of Insubria, Varese, Italy
| | - Isabel Varela-Nieto
- Institute for Biomedical Research "Alberto Sols" (IIBM), Spanish National Research Council-Autonomous University of Madrid (CSIC-UAM), Madrid, Spain.,Rare Diseases Networking Biomedical Research Centre, Centro de Investigación Biomédica en Red, Carlos III Institute of Health, Madrid, Spain.,La Paz Hospital Institute for Health Research (IdiPAZ), Madrid, Spain
| | - Agnieszka J Szczepek
- Department of Otorhinolaryngology, Head and Neck Surgery, Charité-Universitätsmedizin Berlin, Corporate Member of Freie Universität Berlin, Humboldt-Universität zu Berlin, and Berlin Institute of Health, Berlin, Germany.,Faculty of Medicine and Health Sciences, University of Zielona Gora, Zielona Gora, Poland
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46
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Aregueta-Robles UA, Enke YL, Carter PM, Green RA, Poole-Warren LA. Subthreshold Electrical Stimulation for Controlling Protein-Mediated Impedance Increases in Platinum Cochlear Electrode. IEEE Trans Biomed Eng 2020; 67:3510-3520. [DOI: 10.1109/tbme.2020.2989754] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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47
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Shepherd RK, Carter PM, Enke YL, Thompson A, Flynn B, Trang EP, Dalrymple AN, Fallon JB. Chronic intracochlear electrical stimulation at high charge densities: reducing platinum dissolution. J Neural Eng 2020; 17:056009. [DOI: 10.1088/1741-2552/abb7a6] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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48
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Band-Limited Chirp-Evoked Compound Action Potential in Guinea Pig: Comprehensive Neural Measure for Cochlear Implantation Monitoring. Ear Hear 2020; 42:142-162. [PMID: 32665481 DOI: 10.1097/aud.0000000000000910] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES Patients with severely impaired high-frequency hearing and sufficient residual low-frequency hearing can be provided with a cochlear implant (CI), thereby facilitating ipsilateral electric and acoustic stimulation with established advantages over electric stimulation alone. However, partial or complete hearing loss often occurred after implantation due to, inter alia, acute mechanical trauma to cochlear structures during electrode insertion. Possibilities of intraoperative monitoring using electrocochleography (ECochG) have recently been studied in CI patients, primarily using the ongoing response to low-frequency tone bursts consisting of the cochlear microphonic (CM) and the auditory nerve neurophonic. By contrast, the transient neural response to tone bursts, that is, compound action potential (CAP), was generally less detectable or less sensitive as a monitoring measure, thus falling short of providing useful contribution to electrocochleography analysis. In this study, we investigate using chirps to evoke more robust CAP responses in a limited frequency band by synchronizing neural firing, and thereby improving CAP sensitivity to mechanical trauma in a guinea pig model of cochlear implantation. DESIGN Stimuli were band-limited between 100 Hz and 10 kHz to investigate their frequency range selectivity as a preliminary model for low-frequency hearing. They were constructed by adding a harmonic series either with zero phase delay (click) or by adjusting the phase delay at a rate that is inversely related to a traveling wave delay model (chirp), with three different parameters to examine level-dependent delay compression. The amplitude spectrum was thus identical between stimuli with differences only in phase. In Experiment 1, we compared input-output functions recorded at the round window in normal-hearing guinea pigs and implemented a high-pass noise masking paradigm to infer neural contribution to the CAP. In Experiment 2, guinea pigs were implanted with a custom-built CI electrode using a motorized micromanipulator. Acute mechanical trauma was simulated during the electrode insertion. At each insertion step, CAP and CM responses were measured at the round window for the following stimuli: broad-band click, band-limited click, and band-limited chirps (3 parameters), and tone bursts at frequencies 1, 2, 4, and 8 kHz. RESULTS Chirps compared with the equal-band click showed significantly lower thresholds and steeper slopes of sigmoid-fitted input-output functions. The shorter chirp evoked significantly larger amplitudes than click when compared at equal sensation level. However, the click evoked larger amplitudes than chirps at higher levels and correspondingly achieved larger saturation amplitudes. The results of the high-pass noise masking paradigm suggest that chirps could efficiently synchronize neural firing in their targeted frequency band, while the click recruited more basal fibers outside its limited band. Finally, monitoring sensitivity during electrode insertion, defined as relative amplitude change per unit distance, was higher for chirp-evoked CAP and tone burst-evoked CM, but smaller for CAP responses evoked by clicks or tone bursts. CONCLUSION The chirp was shown to be an efficient stimulus in synchronizing neural firing for a limited frequency band in the guinea pig model. This study provides a proof of principle for using chirp-evoked CAP as a comprehensive neural measure in CI patients with residual hearing.
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Dalrymple AN, Huynh M, Nayagam BA, Lee CD, Weiland GR, Petrossians A, J J, Iii W, Fallon JB, Shepherd RK. Electrochemical and biological characterization of thin-film platinum-iridium alloy electrode coatings: a chronic in vivo study. J Neural Eng 2020; 17:036012. [PMID: 32408281 DOI: 10.1088/1741-2552/ab933d] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
OBJECTIVE To evaluate the electrochemical properties, biological response, and surface characterization of an electrodeposited Platinum-Iridium (Pt-Ir) electrode coating on cochlear implants subjected to chronic stimulation in vivo. APPROACH Electrochemical impedance spectroscopy (EIS), charge storage capacity (CSC), charge injection limit (CIL), and voltage transient (VT) impedance were measured bench-top before and after implant and in vivo. Coated Pt-Ir and uncoated Pt electrode arrays were implanted into cochlea of normal hearing rats and stimulated for ∼4 h d, 5 d week-1 for 5 weeks at levels within the normal clinical range. Neural function was monitored using electrically-evoked auditory brainstem responses. After explant, the electrode surfaces were assessed, and cochleae examined histologically. MAIN RESULTS When measured on bench-top before and after stimulation, Pt-Ir coated electrodes had significantly lower VT impedance (p < 0.001) and significantly higher CSC (p < 0.001) and CIL (p < 0.001) compared to uncoated Pt electrodes. In vivo, the CSC and CIL of Pt-Ir were significantly higher than Pt throughout the implantation period (p= 0.047 and p< 0.001, respectively); however, the VT impedance (p= 0.3) was not. There was no difference in foreign body response between material cohorts, although cochleae implanted with coated electrodes contained small deposits of Pt-Ir. There was no evidence of increased neural loss or loss of neural function in either group. Surface examination revealed no Pt corrosion on any electrodes. SIGNIFICANCE Electrodeposited Pt-Ir electrodes demonstrated significant improvements in electrochemical performance on the bench-top and in vivo compared to uncoated Pt. Neural function and tissue response to Pt-Ir electrodes were not different from uncoated Pt, despite small deposits of Pt-Ir in the tissue capsule. Electrodeposited Pt-Ir coatings offer promise as an improved electrode coating for active neural prostheses.
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Simoni E, Gentilin E, Candito M, Borile G, Romanato F, Chicca M, Nordio S, Aspidistria M, Martini A, Cazzador D, Astolfi L. Immune Response After Cochlear Implantation. Front Neurol 2020; 11:341. [PMID: 32477241 PMCID: PMC7240074 DOI: 10.3389/fneur.2020.00341] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/18/2019] [Accepted: 04/07/2020] [Indexed: 12/20/2022] Open
Abstract
A cochlear implant (CI) is an electronic device that enables hearing recovery in patients with severe to profound hearing loss. Although CIs are a successful treatment for profound hearing impairment, their effectivity may be improved by reducing damages associated with insertion of electrodes in the cochlea, thus preserving residual hearing ability. Inner ear trauma leads to inflammatory reactions altering cochlear homeostasis and reducing post-operative audiological performances and electroacoustic stimulation. Strategies to preserve residual hearing ability led to the development of medicated devices to minimize CI-induced cochlear injury. Dexamethasone-eluting electrodes recently showed positive outcomes. In previous studies by our research group, intratympanic release of dexamethasone for 14 days was able to preserve residual hearing from CI insertion trauma in a Guinea pig model. Long-term effects of dexamethasone-eluting electrodes were therefore evaluated in the same animal model. Seven Guinea pigs were bilaterally implanted with medicated rods and four were implanted with non-eluting ones. Hearing threshold audiograms were acquired prior to implantation and up to 60 days by recording compound action potentials. For each sample, we examined the amount of bone and fibrous connective tissue grown within the scala tympani in the basal turn of the cochlea, the cochleostomy healing, the neuronal density, and the correlation between electrophysiological parameters and histological results. Detection of tumor necrosis factor alpha, interleukin-6, and foreign body giant cells showed that long-term electrode implantation was not associated with an ongoing inflammation. Growth of bone and fibrous connective tissue around rods induced by CI was reduced in the scala tympani by dexamethasone release. For cochleostomy sealing, dexamethasone-treated animals showed less bone tissue growth than negative. Dexamethasone did not affect cell density in the spiral ganglion. Overall, these results support the use of dexamethasone as anti-inflammatory additive for eluting electrodes able to protect the cochlea from CI insertion trauma.
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Affiliation(s)
- Edi Simoni
- Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Padua, Italy.,Otorhinolaryngology Unit, Department of Neurosciences, University of Padua, Padua, Italy.,Section of Human Anatomy, Department of Neuroscience, University of Padua, Padua, Italy
| | - Erica Gentilin
- Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Padua, Italy.,Otorhinolaryngology Unit, Department of Neurosciences, University of Padua, Padua, Italy
| | - Mariarita Candito
- Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Padua, Italy.,Otorhinolaryngology Unit, Department of Neurosciences, University of Padua, Padua, Italy
| | - Giulia Borile
- Department of Physics and Astronomy "G. Galilei", University of Padua, Padua, Italy.,Laboratory for Nanofabrication of Nanodevices, Padua, Italy
| | - Filippo Romanato
- Department of Physics and Astronomy "G. Galilei", University of Padua, Padua, Italy.,Laboratory for Nanofabrication of Nanodevices, Padua, Italy
| | - Milvia Chicca
- Department of Life Sciences and Biotechnology, University of Ferrara, Ferrara, Italy
| | - Sara Nordio
- Fondazione Ospedale San Camillo IRCCS, Venice, Italy
| | - Marta Aspidistria
- Department of Statistical Sciences, University of Padua, Padova, Italy
| | - Alessandro Martini
- Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Padua, Italy.,Otorhinolaryngology Unit, Department of Neurosciences, University of Padua, Padua, Italy
| | - Diego Cazzador
- Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Padua, Italy.,Otorhinolaryngology Unit, Department of Neurosciences, University of Padua, Padua, Italy.,Section of Human Anatomy, Department of Neuroscience, University of Padua, Padua, Italy
| | - Laura Astolfi
- Bioacoustics Research Laboratory, Department of Neurosciences, University of Padua, Padua, Italy.,Otorhinolaryngology Unit, Department of Neurosciences, University of Padua, Padua, Italy
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