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Aljazeeri IA, Hagr A. Application of anatomy-based spacing of electrode contacts for achieving a uniform semitonal resolution: A novel concept in cochlear implant electrode design. Sci Rep 2024; 14:2645. [PMID: 38302541 PMCID: PMC10834526 DOI: 10.1038/s41598-024-53070-8] [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: 09/19/2023] [Accepted: 01/27/2024] [Indexed: 02/03/2024] Open
Abstract
Using anatomy-based fitting, we can determine the place-specific map with individualized center frequencies for each electrode contact that is a closer match to the natural pitch-place of the cochlea. The primary objective of this study is to evaluate the tonal presentation across the electrode array and to calculate the semitone difference between each adjacent pair of contacts according to their anatomy-based map. The secondary objective is to determine the distancing of the contacts that would result in an equal semitone difference with a uniform tonal presentation. A total of 167 ears were included in this retrospective study. The frequencies across the electrode arrays were found to be unequally presented. The semitonal condensations were higher in the apical inter-contact spaces compared to the basal inter-contact spaces, being 3.0-2.3 semitones/mm (Kruskal Wallis test, p < 0.000). The anatomy-based spacing of the electrode contacts was larger in the basal inter-contact spaces compared to the apical inter-contact spaces, ranging from 1.92 to 1.48 mm. In conclusion, the current electrode designs do not have uniform tonal representation throughout the electrode array. There is a more condensed tonal presentation in the apical electrodes than in the basal electrodes, resulting in a lower tonal resolution in the apical region.
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Affiliation(s)
- Isra Ali Aljazeeri
- King Abdullah Ear Specialist Center (KAESC), College of Medicine, King Saud University Medical City (KSUMC), King Saud University, PO Box 245, 11411, Riyadh, Saudi Arabia.
- Otolaryngology and Ophthalmology Specialized Aljaber Hospital, Ministry of Health, Ahsa, Saudi Arabia.
| | - Abdulrahman Hagr
- King Abdullah Ear Specialist Center (KAESC), College of Medicine, King Saud University Medical City (KSUMC), King Saud University, PO Box 245, 11411, Riyadh, Saudi Arabia
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Vink HA, Ramekers D, Foster AC, Versnel H. The efficacy of a TrkB monoclonal antibody agonist in preserving the auditory nerve in deafened guinea pigs. Hear Res 2023; 439:108895. [PMID: 37837701 DOI: 10.1016/j.heares.2023.108895] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2023] [Revised: 08/31/2023] [Accepted: 10/02/2023] [Indexed: 10/16/2023]
Abstract
The auditory nerve typically degenerates following loss of cochlear hair cells or synapses. In the case of hair cell loss neural degeneration hinders restoration of hearing through a cochlear implant, and in the case of synaptopathy suprathreshold hearing is affected, potentially degrading speech perception in noise. It has been established that neurotrophins such as brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) can mitigate auditory nerve degeneration. Several potential BDNF mimetics have also been investigated for neurotrophic effects in the cochlea. A recent in vitro study showed favorable effects of M3, a TrkB monoclonal antibody agonist, when compared with BDNF. In the present study we set out to examine the effect of M3 on auditory nerve preservation in vivo. Thirty-one guinea pigs were bilaterally deafened, and unilaterally treated with a single 3-µl dose of 7 mg/ml, 0.7 mg/ml M3 or vehicle-only by means of a small gelatin sponge two weeks later. During the experiment and analyses the experimenters were blinded to the three treatment groups. Four weeks after treatment, we assessed the treatment effect (1) histologically, by quantifying survival of SGCs and their peripheral processes (PPs); and (2) electrophysiologically, with two different paradigms of electrically evoked compound action potential (eCAP) recordings shown to be indicative of neural health: single-pulse stimulation with varying inter-phase gap (IPG), and pulse-train stimulation with varying inter-pulse interval. We observed a consistent and significant preservative effect of M3 on SGC survival in the lower basal turn (approximately 40% more survival than in the untreated contralateral cochlea), but also in the upper middle and lower apical turn of the cochlea. This effect was similar for the two treatment groups. Survival of PPs showed a trend similar to that of the SGCs, but was only significantly higher for the highest dose of M3. The protective effect of M3 on SGCs was not reflected in any of the eCAP measures: no statistically significant differences were observed between groups in IPG effect nor between the M3 treatment groups and the control group using the pulse-train stimulation paradigm. In short, while a clear effect of M3 was observed on SGC survival, this was not clearly translated into functional preservation.
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Affiliation(s)
- Henk A Vink
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht University, Room G.02.531, P.O. Box 85500, 3508 GA, Utrecht, the Netherlands; UMC Utrecht Brain Center, Utrecht University, Utrecht, the Netherlands
| | - Dyan Ramekers
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht University, Room G.02.531, P.O. Box 85500, 3508 GA, Utrecht, the Netherlands; UMC Utrecht Brain Center, Utrecht University, Utrecht, the Netherlands
| | | | - Huib Versnel
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht University, Room G.02.531, P.O. Box 85500, 3508 GA, Utrecht, the Netherlands; UMC Utrecht Brain Center, Utrecht University, Utrecht, the Netherlands.
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Gunewardene N, Ma Y, Lam P, Wagstaff S, Cortez-Jugo C, Hu Y, Caruso F, Richardson RT, Wise AK. Developing the supraparticle technology for round window-mediated drug administration into the cochlea. J Control Release 2023; 361:621-635. [PMID: 37572963 DOI: 10.1016/j.jconrel.2023.08.016] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/04/2023] [Revised: 08/04/2023] [Accepted: 08/09/2023] [Indexed: 08/14/2023]
Abstract
The semi-permeable round window membrane (RWM) is the gateway to the cochlea. Although the RWM is considered a minimally invasive and clinically accepted route for localised drug delivery to the cochlea, overcoming this barrier is challenging, hindering development of effective therapies for hearing loss. Neurotrophin 3 (NT3) is an emerging treatment option for hearing loss, but its therapeutic effect relies on sustained delivery across the RWM into the cochlea. Silica supraparticles (SPs) are drug delivery carriers capable of providing long-term NT3 delivery, when injected directly into the guinea pig cochlea. However, for clinical translation, a RWM delivery approach is desirable. Here, we aimed to test approaches to improve the longevity and biodistribution of NT3 inside the cochlea after RWM implantation of SPs in guinea pigs and cats. Three approaches were tested (i) coating the SPs to slow drug release (ii) improving the retention of SPs on the RWM using a clinically approved gel formulation and (iii) permeabilising the RWM with hyaluronic acid. A radioactive tracer (iodine 125: 125I) tagged to NT3 (125I NT3) was loaded into the SPs to characterise drug pharmacokinetics in vitro and in vivo. The neurotrophin-loaded SPs were coated using a chitosan and alginate layer-by-layer coating strategy, named as '(Chi/Alg)SPs', to promote long term drug release. The guinea pigs were implanted with 5× 125I NT3 loaded (Chi/Alg) SPs on the RWM, while cats were implanted with 30× (Chi/Alg) SPs. A cohort of animals were also implanted with SPs (controls). We found that the NT3 loaded (Chi/Alg)SPs exhibited a more linear release profile compared to NT3 loaded SPs alone. The 125I NT3 loaded (Chi/Alg)SPs in fibrin sealant had efficient drug loading (~5 μg of NT3 loaded per SP that weights ~50 μg) and elution capacities (~49% over one month) in vitro. Compared to the SPs in fibrin sealant, the (Chi/Alg)SPs in fibrin sealant had a significantly slower 125I NT3 drug release profile over the first 7 days in vitro (~12% for (Chi/Alg) SPs in fibrin sealant vs ~43% for SPs in fibrin sealant). One-month post-implantation of (Chi/Alg) SPs, gamma count measurements revealed an average of 0.3 μg NT3 remained in the guinea pig cochlea, while for the cat, 1.3 μg remained. Histological analysis of cochlear tissue revealed presence of a 125I NT3 signal localised in the basilar membrane of the lower basal turn in some cochleae after 4 weeks in guinea pigs and 8 weeks in cats. Comparatively, and in contrast to the in vitro release data, implantation of the SPs presented better NT3 retention and distribution inside the cochlea in both the guinea pigs and cats. No significant difference in drug entry was observed upon acute treatment of the RWM with hyaluronic acid. Collectively, our findings indicate that SPs and (Chi/Alg)SPs can facilitate drug transfer across the RWM, with detectable levels inside the cat cochlea even after 8 weeks with the intracochlear approach. This is the first study to examine neurotrophin pharmacokinetics in the cochlea for such an extended period of times in these two animal species. Whilst promising, we note that outcomes between animals were variable, and opposing results were found between in vitro and in vivo release studies. These findings have important clinical ramifications, emphasising the need to understand the physical properties and mechanics of this complex barrier in parallel with the development of therapies for hearing loss.
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Affiliation(s)
- Niliksha Gunewardene
- Bionics Institute, East Melbourne, Victoria 3002, Australia; Department of Medical Bionics, The University of Melbourne, Fitzroy, Victoria 3065, Australia.
| | - Yutian Ma
- Bionics Institute, East Melbourne, Victoria 3002, Australia; Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Patrick Lam
- Bionics Institute, East Melbourne, Victoria 3002, Australia
| | | | - Christina Cortez-Jugo
- Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Yingjie Hu
- Bionics Institute, East Melbourne, Victoria 3002, Australia; Department of Medical Bionics, The University of Melbourne, Fitzroy, Victoria 3065, Australia; Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Frank Caruso
- Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Rachael T Richardson
- Bionics Institute, East Melbourne, Victoria 3002, Australia; Department of Medical Bionics, The University of Melbourne, Fitzroy, Victoria 3065, Australia; Department of Surgery (Otolaryngology), University of Melbourne, The Royal Victorian Eye and Ear Hospital, East Melbourne, Victoria 3002, Australia
| | - Andrew K Wise
- Bionics Institute, East Melbourne, Victoria 3002, Australia; Department of Medical Bionics, The University of Melbourne, Fitzroy, Victoria 3065, Australia.
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Sander KL, Warren SE, Mendel LL. Survey of selective electrode deactivation attitudes and practices by cochlear implant audiologists. Cochlear Implants Int 2023; 24:167-175. [PMID: 36732065 DOI: 10.1080/14670100.2023.2166571] [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: 02/04/2023]
Abstract
OBJECTIVES The purpose of this study was to explore clinician attitudes regarding selective electrode deactivation and to investigate the primary methodology used to identify poorly encoded electrodes, deactivate identified electrodes, and measure outcomes. METHODS An online survey consisting of 32 questions was administered to certified clinical and research cochlear implant (CI) audiologists. Questions asked participants about their demographic information, device programming patterns, and attitudes regarding selective electrode deactivation. RESULTS Fifty-four audiologists completed the survey. When asked whether they believed selectively deactivating poorly encoded electrodes could improve speech perception outcomes, 43% of respondents selected 'Probably Yes,' 39% selected 'Definitely Yes,' and 18% selected 'Might or Might Not.' Of those who reported deactivating electrodes as part of CI programming, various methodology was reported to identify and deactivate poorly encoding electrodes and evaluate effectiveness of deactivation. General reasons against deactivation were also reported. DISCUSSION CI audiologists generally believed selective electrode deactivation could be used to improve speech perception outcomes for patients; however, few reported implementing selective electrode deactivation in practice. Among those who do perform selective electrode deactivation, the reported methodology was highly variable. CONCLUSION These findings support the need for clinical practice guidelines to assist audiologists in performing selective electrode deactivation.
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Affiliation(s)
- Kara L Sander
- Department of Communication Sciences and Disorders, University of Memphis, Memphis, TN, USA
| | - Sarah E Warren
- Department of Communication Sciences and Disorders, University of Memphis, Memphis, TN, USA
| | - Lisa Lucks Mendel
- Department of Communication Sciences and Disorders, University of Memphis, Memphis, TN, USA
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Closing the Gap between the Auditory Nerve and Cochlear Implant Electrodes: Which Neurotrophin Cocktail Performs Best for Axonal Outgrowth and Is Electrical Stimulation Beneficial? Int J Mol Sci 2023; 24:ijms24032013. [PMID: 36768339 PMCID: PMC9916558 DOI: 10.3390/ijms24032013] [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: 11/29/2022] [Revised: 01/12/2023] [Accepted: 01/14/2023] [Indexed: 01/22/2023] Open
Abstract
Neurotrophins promote neurite outgrowth of auditory neurons and may help closing the gap to cochlear implant (CI) electrodes to enhance electrical hearing. The best concentrations and mix of neurotrophins for this nerve regrowth are unknown. Whether electrical stimulation (ES) during outgrowth is beneficial or may direct axons is another open question. Auditory neuron explant cultures of distinct cochlear turns of 6-7 days old mice were cultured for four days. We tested different concentrations and combinations of BDNF and NT-3 and quantified the numbers and lengths of neurites with an advanced automated analysis. A custom-made 24-well electrical stimulator based on two bulk CIs served to test different ES strategies. Quantification of receptors trkB, trkC, p75NTR, and histological analysis helped to analyze effects. We found 25 ng/mL BDNF to perform best, especially in basal neurons, a negative influence of NT-3 in combined BDNF/NT-3 scenarios, and tonotopic changes in trk and p75NTR receptor stainings. ES largely impeded neurite outgrowth and glia ensheathment in an amplitude-dependent way. Apical neurons showed slight benefits in neurite numbers and length with ES at 10 and 500 µA. We recommend BDNF as a potent drug to enhance the man-machine interface, but CIs should be better activated after nerve regrowth.
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Vink HA, Ramekers D, Thomeer HGXM, Versnel H. Combined brain-derived neurotrophic factor and neurotrophin-3 treatment is preferred over either one separately in the preservation of the auditory nerve in deafened guinea pigs. Front Mol Neurosci 2022; 15:935111. [PMID: 36226314 PMCID: PMC9549372 DOI: 10.3389/fnmol.2022.935111] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2022] [Accepted: 08/30/2022] [Indexed: 11/13/2022] Open
Abstract
Severe hearing loss or deafness is often caused by cochlear hair cell loss and can be mitigated by a cochlear implant (CI). CIs target the auditory nerve, consisting of spiral ganglion cells (SGCs), which degenerate gradually, following hair cell loss. In animal models, it has been established that treatment with the neurotrophins brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT-3) reduce SGC degeneration. In this study, we aimed to investigate whether treatment with both BDNF and NT-3 (Cocktail) is superior to treatment with each neurotrophin separately regarding cell preservation and neural responsiveness to electrical stimulation. To this end, deafened guinea pigs received neurotrophic treatment in their right ear via a gelatin sponge on the perforated round window membrane, followed by cochlear implantation 4 weeks later in the same ear for electrophysiological recordings to various stimulation paradigms. Normal-hearing and deafened untreated guinea pigs were included as positive and negative controls, respectively. Substantial SGC loss occurred in all deafened animals. Each of the neurotrophic treatments led to enhanced SGC survival mainly in the basal turn of the cochlea, gradually decreasing toward the apex. The Cocktail treatment resulted in the highest SGC survival in the treated ear, followed by BDNF, with the least protection of SGCs following NT-3 treatment. Survival of the SGC’s peripheral processes (PPs) followed the same trend in response to the treatment. However, survival of SGCs and PPs in the contralateral untreated ears was also highest in the Cocktail group. Consequently, analysis of the ratio between the treated and untreated ears showed that the BDNF group, which showed low SGC survival in the untreated ear, had the highest relative SGC survival of the three neurotrophin-treated groups. Neurotrophic treatment had positive effects in part of the electrically evoked compound action-potential recording paradigms. These effects were only observed for the BDNF or Cocktail treatment. We conclude that treatment with either BDNF or a cocktail of BDNF and NT-3 is preferred to NT-3 alone. Furthermore, since the Cocktail treatment resulted in better electrophysiological responsiveness and overall higher SGC survival than BDNF alone, we are inclined to recommend the Cocktail treatment rather than BDNF alone.
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Affiliation(s)
- Henk A. Vink
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
- UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
| | - Dyan Ramekers
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
- UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
- *Correspondence: Dyan Ramekers,
| | - Hans G. X. M. Thomeer
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
- UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
| | - Huib Versnel
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
- UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
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Reiss LA, Kirk J, Claussen AD, Fallon JB. Animal Models of Hearing Loss after Cochlear Implantation and Electrical Stimulation. Hear Res 2022; 426:108624. [DOI: 10.1016/j.heares.2022.108624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/24/2021] [Revised: 03/28/2022] [Accepted: 09/23/2022] [Indexed: 11/04/2022]
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Goyal MM, Zhou NJ, Vincent PFY, Hoffman ES, Goel S, Wang C, Sun DQ. Rationally Designed Magnetic Nanoparticles for Cochlear Drug Delivery: Synthesis, Characterization, and In Vitro Biocompatibility in a Murine Model. OTOLOGY & NEUROTOLOGY OPEN 2022; 2:e013. [PMID: 38516629 PMCID: PMC10950169 DOI: 10.1097/ono.0000000000000013] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 06/03/2022] [Indexed: 03/23/2024]
Abstract
Hypothesis Magnetic nanoparticles (MNPs) for cochlear drug delivery can be precisely engineered for biocompatibility in the cochlea. Background MNPs are promising drug delivery vehicles that can enhance the penetration of both small and macromolecular therapeutics into the cochlea. However, concerns exist regarding the application of oxidative, metal-based nanomaterials to delicate sensory tissues of the inner ear. Translational development of MNPs for cochlear drug deliver requires specifically tuned nanoparticles that are not cytotoxic to inner ear tissues. We describe the synthesis and characterization of precisely tuned MNP vehicles, and their in vitro biocompatibility in murine organ of Corti organotypic cultures. Methods MNPs were synthesized via 2-phase ligand transfer process with precise control of nanoparticle size. Core and hydrodynamic sizes of nanoparticles were characterized using electron microscopy and dynamic light scattering, respectively. In vitro biocompatibility was assayed via mouse organ of Corti organotypic cultures with and without an external magnetic field gradient. Imaging was performed using immunohistochemical labeling and confocal microscopy. Outer hair cell, inner hair cell, and spiral ganglion neurites were individually quantified. Results Monocore PEG-MNPs of 45 and 148 nm (mean hydrodynamic diameter) were synthesized. Organ of Corti cultures demonstrated preserved outer hair cell, inner hair cell, and neurite counts across 2 MNP sizes and doses, and irrespective of external magnetic field gradient. Conclusion MNPs can be custom-synthesized with precise coating, size, and charge properties specific for cochlear drug delivery while also demonstrating biocompatibility in vitro.
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Affiliation(s)
- Mukund M. Goyal
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD
| | - Nancy J. Zhou
- School of Medicine, Johns Hopkins University, Baltimore, MD
| | - Philippe F. Y. Vincent
- Department of Otolaryngology – Head and Neck Surgery, Johns Hopkins University, Baltimore, MD
| | - Elina S. Hoffman
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD
| | - Shiv Goel
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD
| | - Chao Wang
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD
| | - Daniel Q. Sun
- Department of Otolaryngology – Head and Neck Surgery, Johns Hopkins University, Baltimore, MD
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Gunewardene N, Lam P, Ma Y, Caruso F, Wagstaff S, Richardson RT, Wise AK. Pharmacokinetics and biodistribution of supraparticle-delivered neurotrophin 3 in the guinea pig cochlea. J Control Release 2022; 342:295-307. [PMID: 34999140 DOI: 10.1016/j.jconrel.2021.12.037] [Citation(s) in RCA: 7] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2021] [Accepted: 12/29/2021] [Indexed: 02/06/2023]
Abstract
Hearing loss is the most prevalent sensory disorder affecting nearly half a billion people worldwide. Aside from devices to assist hearing, such as hearing aids and cochlear implants, a drug treatment for hearing loss has yet to be developed. The neurotrophin family of growth factors has long been established as a potential therapy, however delivery of these factors into the inner ear at therapeutic levels over a sustained period of time has remained a challenge restricting clinical translation. We previously demonstrated that direct delivery of exogenous neurotrophin-3 (NT3) in the guinea pig cochleae via a bolus injection was rapidly cleared from the inner ear, with almost complete elimination 3 days post-treatment. Here, we explored the potential of suprapaticles (SPs) for NT3 delivery to the inner ear to achieve sustained delivery over time. SPs are porous spheroid structures comprised of smaller colloidal silica nanoparticles that provide a platform for long-term controlled release of therapeutics. This study aimed to assess the pharmacokinetics and biodistribution of SP-delivered NT3. We used a radioactive tracer (iodine 125: 125I) to label the NT3 to determine the loading, retention and distribution of NT3 delivered via SPs. Gamma measurements taken from 125I NT3 loaded SPs revealed high drug loading (an average of 5.3 μg of NT3 loaded per SP weighing 50 μg) and elution capacities in vitro (67% cumulative release over one month). Whole cochlear gamma measurements from SP-implanted cochleae harvested at various time points revealed detection of 125I NT3 in the guinea pig cochlea after one month, with 3.6 and 10% of the loaded drug remaining in the intracochlear and round window-implanted cochleae respectively. Autoradiography analysis of cochlear micro-sections revealed widespread 125I NT3 distribution after intracochlear SP delivery, but more restricted distribution with the round window delivery approach. Collectively, drug delivery into the inner ear using SPs support sustained, long-term availability and release of neurotrophins in the inner ear.
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Affiliation(s)
- Niliksha Gunewardene
- Bionics Institute, Melbourne, Australia; Medical Bionics Department, University of Melbourne, Australia.
| | | | - Yutian Ma
- Bionics Institute, Melbourne, Australia; ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia
| | - Frank Caruso
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Department of Chemical Engineering, The University of Melbourne, Parkville, Victoria 3010, Australia
| | | | - Rachael T Richardson
- Bionics Institute, Melbourne, Australia; Medical Bionics Department, University of Melbourne, Australia; Department of Surgery (Otolaryngology), University of Melbourne, Australia
| | - Andrew K Wise
- Bionics Institute, Melbourne, Australia; Medical Bionics Department, University of Melbourne, Australia; Department of Surgery (Otolaryngology), University of Melbourne, Australia.
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Zu M, Guo WW, Cong T, Ji F, Zhang SL, Zhang Y, Song X, Sun W, He DZZ, Shi WG, Yang SM. SCN11A gene deletion causes sensorineural hearing loss by impairing the ribbon synapses and auditory nerves. BMC Neurosci 2021; 22:18. [PMID: 33752606 PMCID: PMC7986359 DOI: 10.1186/s12868-021-00613-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/30/2020] [Accepted: 01/20/2021] [Indexed: 11/10/2022] Open
Abstract
Background The SCN11A gene, encoded Nav1.9 TTX resistant sodium channels, is a main effector in peripheral inflammation related pain in nociceptive neurons. The role of SCN11A gene in the auditory system has not been well characterized. We therefore examined the expression of SCN11A in the murine cochlea, the morphological and physiological features of Nav1.9 knockout (KO) ICR mice. Results Nav1.9 expression was found in the primary afferent endings beneath the inner hair cells (IHCs). The relative quantitative expression of Nav1.9 mRNA in modiolus of wild-type (WT) mice remains unchanged from P0 to P60. The number of presynaptic CtBP2 puncta in Nav1.9 KO mice was significantly lower than WT. In addition, the number of SGNs in Nav1.9 KO mice was also less than WT in the basal turn, but not in the apical and middle turns. There was no lesion in the somas and stereocilia of hair cells in Nav1.9 KO mice. Furthermore, Nav1.9 KO mice showed higher and progressive elevated ABR threshold at 16 kHz, and a significant increase in CAP thresholds. Conclusions These data suggest a role of Nav1.9 in regulating the function of ribbon synapses and the auditory nerves. The impairment induced by Nav1.9 gene deletion mimics the characters of cochlear synaptopathy.
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Affiliation(s)
- Mian Zu
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment for Prevention and Treatment, Beijing, China
| | - Wei-Wei Guo
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment for Prevention and Treatment, Beijing, China
| | - Tao Cong
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment for Prevention and Treatment, Beijing, China
| | - Fei Ji
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment for Prevention and Treatment, Beijing, China
| | - Shi-Li Zhang
- Clinical Hearing Center of Affiliated Hospital of Xuzhou Medical University, Xuzhou, Jiangsu, China
| | - Yue Zhang
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment for Prevention and Treatment, Beijing, China
| | - Xin Song
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Beijing, China.,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China.,Key Lab of Hearing Science, Ministry of Education, Beijing, China.,Beijing Key Lab of Hearing Impairment for Prevention and Treatment, Beijing, China
| | - Wei Sun
- Department of Communicative Disorders and Sciences, Center for Hearing and Deafness, The State University of New York at Buffalo, Buffalo, NY, USA
| | - David Z Z He
- Department of Biomedical Sciences, Creighton University School of Medicine, Omaha, NE, 68178, USA
| | - Wei-Guo Shi
- State Key Laboratory of Toxicology and Medical Countermeasures, Beijing Institute of Pharmacology and Toxicology, Beijing, China.
| | - Shi-Ming Yang
- College of Otolaryngology Head and Neck Surgery, Chinese PLA General Hospital, Beijing, China. .,National Clinical Research Center for Otolaryngologic Diseases, Beijing, China. .,Key Lab of Hearing Science, Ministry of Education, Beijing, China. .,Beijing Key Lab of Hearing Impairment for Prevention and Treatment, Beijing, China.
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11
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Vink HA, Versnel H, Kroon S, Klis SFL, Ramekers D. BDNF-mediated preservation of spiral ganglion cell peripheral processes and axons in comparison to that of their cell bodies. Hear Res 2020; 400:108114. [PMID: 33271438 DOI: 10.1016/j.heares.2020.108114] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/01/2020] [Revised: 10/21/2020] [Accepted: 11/10/2020] [Indexed: 01/19/2023]
Abstract
Treatment with neurotrophins prevents degeneration of spiral ganglion cells (SGCs) after severe hair cell loss. In a previous study we demonstrated a long-lasting effect with brain-derived neurotrophic factor (BDNF) after cessation of treatment. In that study the survival of the SGC cell bodies was examined. Here we address the question whether their peripheral processes and central processes (axons) were protected by this treatment as well in the cochleas of the aforementioned study. Guinea pigs were deafened by co-administration of kanamycin and furosemide. Two weeks after deafening the right cochleas were implanted with an intracochlear electrode array combined with a cannula connected to an osmotic pump filled with BDNF solution. Four weeks later the treatment was stopped by surgically removing the osmotic pump. At that point, or another four or eight weeks later, the animals were sacrificed for histological analysis. Control groups consisted of normal-hearing animals, and three groups of deafened animals: two-weeks-deaf untreated animals, and six- and fourteen-weeks-deaf sham-treated animals. Cochleas were processed for analysis of: (1) the myelinated portion of peripheral processes in the osseous spiral lamina, (2) the cell bodies in Rosenthal's canal, and (3) axons in the internal acoustic meatus. Packing densities and cross-sectional areas were determined using light microscopy. Up to eight weeks after treatment cessation the numbers of peripheral processes and axons were significantly higher than in untreated cochleas of control animals. Whereas the numbers of cell bodies and axons were similar to those at the start of treatment, the peripheral processes were significantly less well preserved. This smaller protective effect was found mainly in the apical turns. Strategies to prevent SGC degeneration after hair cell loss should consider the differential effects on the various neural elements.
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Affiliation(s)
- Henk A Vink
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht University, Room G.02.531, P.O. Box 85500, 3508 GA, Utrecht, the Netherlands; UMC Utrecht Brain Center, Utrecht University, Utrecht, the Netherlands.
| | - Huib Versnel
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht University, Room G.02.531, P.O. Box 85500, 3508 GA, Utrecht, the Netherlands; UMC Utrecht Brain Center, Utrecht University, Utrecht, the Netherlands.
| | - Steven Kroon
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht University, Room G.02.531, P.O. Box 85500, 3508 GA, Utrecht, the Netherlands
| | - Sjaak F L Klis
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht University, Room G.02.531, P.O. Box 85500, 3508 GA, Utrecht, the Netherlands; UMC Utrecht Brain Center, Utrecht University, Utrecht, the Netherlands.
| | - Dyan Ramekers
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht University, Room G.02.531, P.O. Box 85500, 3508 GA, Utrecht, the Netherlands; UMC Utrecht Brain Center, Utrecht University, Utrecht, the Netherlands.
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12
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BDNF Outperforms TrkB Agonist 7,8,3'-THF in Preserving the Auditory Nerve in Deafened Guinea Pigs. Brain Sci 2020; 10:brainsci10110787. [PMID: 33126525 PMCID: PMC7692073 DOI: 10.3390/brainsci10110787] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2020] [Revised: 10/23/2020] [Accepted: 10/27/2020] [Indexed: 02/06/2023] Open
Abstract
In deaf subjects using a cochlear implant (CI) for hearing restoration, the auditory nerve is subject to degeneration, which may negatively impact CI effectiveness. This nerve degeneration can be reduced by neurotrophic treatment. Here, we compare the preservative effects of the naturally occurring tyrosine receptor kinase B (TrkB) agonist brain-derived neurotrophic factor (BDNF) and the small-molecule TrkB agonist 7,8,3′-trihydroxyflavone (THF) on the auditory nerve in deafened guinea pigs. THF may be more effective than BDNF throughout the cochlea because of better pharmacokinetic properties. The neurotrophic compounds were delivered by placement of a gelatin sponge on the perforated round window membrane. To complement the histology of spiral ganglion cells (SGCs), electrically evoked compound action potential (eCAP) recordings were performed four weeks after treatment initiation. We analyzed the eCAP inter-phase gap (IPG) effect and measures derived from pulse-train evoked eCAPs, both indicative of SGC healthiness. BDNF but not THF yielded a significantly higher survival of SGCs in the basal cochlear turn than untreated controls. Regarding IPG effect and pulse-train responses, the BDNF-treated animals exhibited more normal responses than both untreated and THF-treated animals. We have thus confirmed the protective effect of BDNF, but we have not confirmed previously reported protective effects of THF with our clinically applicable delivery method.
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13
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Danielian A, Ishiyama G, Lopez IA, Ishiyama A. Morphometric linear and angular measurements of the human cochlea in implant patients using 3-dimensional reconstruction. Hear Res 2019; 386:107874. [PMID: 31893539 DOI: 10.1016/j.heares.2019.107874] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/20/2019] [Revised: 12/16/2019] [Accepted: 12/18/2019] [Indexed: 10/25/2022]
Abstract
The present study is the first to evaluate the spiral ganglion neurons (SGNs) and the linear and angular measurements of the cochlea in temporal bones of cochlear implant (CI) recipients. There are no studies evaluating the morphometric measures in subjects after long-term CI use, and this study fills in this gap in current knowledge, greatly important for the design of CI electrodes. Amira based 3-D reconstructions of the cochlea were generated from stained histopathological slides of 15 celloidin-embedded human temporal bones. The SGN angular distance from the round window exhibited a narrow range from 684°-704°, corresponding to linear distances of 17.87 and 34.48 mm along the inner and outer wall of the scala tympani. The first turn measured an average of 14.21 mm along the inner wall and 23.92 mm along the outer wall. The outer wall average for the second turn was 11.11 mm and for the partial third apical turn was only 4.49 mm. The range for cochlear duct angular distance was 876° to 1051°, with a mean of 2.63 turns, corresponding to an average linear distance of 39.53 mm, ranging from 35.44 mm to 43.57 mm 6 out of 15 temporal bones demonstrated better preservation of SGN in the middle and apical segments of Rosenthal's canal. The present study demonstrates that the anatomy of the cochlea of CI patients does not differ significantly from that of normative subjects and establishes measurements using the round window as the 0° reference point, an important surgical landmark. The relevance of the measurements to cochlear implant design are discussed.
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Affiliation(s)
- Arman Danielian
- UCLA David Geffen School of Medicine Department of Head and Neck Surgery, Los Angeles, CA, 90095, USA
| | - Gail Ishiyama
- UCLA David Geffen School of Medicine Department of Neurology, Los Angeles, CA, 90095, USA
| | - Ivan A Lopez
- UCLA David Geffen School of Medicine Department of Head and Neck Surgery, Los Angeles, CA, 90095, USA
| | - Akira Ishiyama
- UCLA David Geffen School of Medicine Department of Head and Neck Surgery, Los Angeles, CA, 90095, USA.
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14
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Nunez DA, Wijesinghe P, Nabi S, Yeh D, Garnis C. microRNAs in sudden hearing loss. Laryngoscope 2019; 130:E416-E422. [PMID: 31603566 DOI: 10.1002/lary.28327] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2019] [Revised: 08/10/2019] [Accepted: 09/05/2019] [Indexed: 12/11/2022]
Abstract
OBJECTIVES To compare the circulating microRNA (miRNA) expression profiles between sudden sensory neural hearing loss (SSNHL) patients and age-matched normal hearing controls. STUDY DESIGN Prospective cohort multi-center study. METHODS Patients presenting within 28 days of onset of SSNHL were prospectively recruited along with contemporaneous age-matched controls. Pooled sera of four patient (n = 09, mean age = 53.0 years; 07, 55.0; 10, 52.9; 10, 51.6) and two control (09, 51.2 and 03, 50.0) groups were assessed using a TaqMan Low Density Array. The patients' sera were also divided into two pools, untreated (04, 57.7) and treated (32, 52.6) for additional analysis. miRNA expression level was derived from cycle threshold (Ct) values normalized to a global mean. Inter-group mean Ct differences with fold changes ≥2.0 and ≤0.5 at P < .05 were considered significant. Bioinformatic databases were used to identify putative target mRNAs or validated genes and their functional annotations. RESULTS Thirty-six SSNHL patients (mean age 53.0 ± standard deviation (SD) 15.2 years) and 12 controls (50.9 ± 11.9) were studied. Eight miRNAs hsa-miR-590-5p/ -186-5p/ -195-5p/ -140-3p/ -128-3p/ -132-3p/ -375-3p, and -30a-3p were identified as significantly differentially expressed in SSNHL patients. Most of these miRNAs were abundantly identified in the nervous system and the putative target messenger RNAs (mRNAs) were enriched in signaling pathways such as phosphatidyl inositol 3 kinase/protein Kinase B (PI3K/Akt), Ras and mitogen-activated protein kinase (MAPK). CONCLUSION These findings suggest the possible cellular signaling pathways that underlie the disruption of auditory signal transmission in SSNHL. LEVEL OF EVIDENCE 2 Laryngoscope, 130:E416-E422, 2020.
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Affiliation(s)
- Desmond A Nunez
- Division of Otolaryngology, Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada.,Vancouver Coastal Health Research Institute, Vancouver, British Columbia, Canada.,Division of Otolaryngology-Head and Neck Surgery, Vancouver General Hospital, Vancouver, British Columbia, Canada
| | - Printha Wijesinghe
- Division of Otolaryngology, Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada.,Vancouver Coastal Health Research Institute, Vancouver, British Columbia, Canada
| | - Shahin Nabi
- Division of Otolaryngology, Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada.,Division of Otolaryngology-Head and Neck Surgery, Lion Gates Hospital, North Vancouver, British Columbia, Canada
| | - David Yeh
- Division of Otolaryngology-Head and Neck Surgery, Lion Gates Hospital, North Vancouver, British Columbia, Canada
| | - Cathie Garnis
- Division of Otolaryngology, Department of Surgery, University of British Columbia, Vancouver, British Columbia, Canada.,Department of Integrative Oncology, British Columbia Cancer Research Centre, Vancouver, British Columbia, Canada
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15
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Abstract
Over 450 million people worldwide suffer from hearing loss, leading to an estimated economic burden of ∼$750 billion. The past decade has seen significant advances in the understanding of the molecular mechanisms that contribute to hearing, and the environmental and genetic factors that can go awry and lead to hearing loss. This in turn has sparked enormous interest in developing gene therapy approaches to treat this disorder. This review documents the most recent advances in cochlear gene therapy to restore hearing loss, and will cover viral vectors and construct designs, potential routes of delivery into the inner ear, and, lastly, the most promising genes of interest.
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Affiliation(s)
- Lawrence Lustig
- Department of Otolaryngology-Head and Neck Surgery, Columbia University Medical Center, New York Presbyterian Hospital, New York, New York 10032
| | - Omar Akil
- Department of Otolaryngology-Head and Neck Surgery, University of California San Francisco, San Francisco, California 94117
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16
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Abbas L, Rivolta MN. The use of animal models to study cell transplantation in neuropathic hearing loss. Hear Res 2019; 377:72-87. [DOI: 10.1016/j.heares.2019.03.014] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/14/2018] [Revised: 03/12/2019] [Accepted: 03/15/2019] [Indexed: 01/29/2023]
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Bas E, Anwar MR, Goncalves S, Dinh CT, Bracho OR, Chiossone JA, Van De Water TR. Laminin-coated electrodes improve cochlear implant function and post-insertion neuronal survival. Neuroscience 2019; 410:97-107. [PMID: 31059743 DOI: 10.1016/j.neuroscience.2019.04.048] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2018] [Revised: 04/17/2019] [Accepted: 04/24/2019] [Indexed: 12/20/2022]
Abstract
The benefits of Cochlear implant (CI) technology depend among other factors on the proximity of the electrode array to the spiral ganglion neurons. Laminin, a component of the extracellular matrix, regulates Schwann cell proliferation and survival as well as reorganization of actin fibers within their cytoskeleton, which is necessary for myelination of peripheral axons. In this study we explore the effectiveness of laminin-coated electrodes in promoting neuritic outgrowth from auditory neurons towards the electrode array and the ability to reduce acoustic and electric auditory brainstem response (i.e. aABR and eABR) thresholds. In vitro: Schwann cells and neurites are attracted towards laminin-coated surfaces with longer neuritic processes in laminin-coated dishes compared to uncoated dishes. In vivo: Animals implanted with laminin-coated electrodes experience significant decreases in eABR and aABR thresholds at selected frequencies compared to the results from the uncoated electrodes group. At 1 month post implantation there were a greater number of spiral ganglion neurons and neuritic processes projecting into the scala tympani of animals implanted with laminin-coated electrodes compared to animals with uncoated electrodes. These data suggest that Schwann cells are attracted towards laminin-coated electrodes and promote neuritic outgrowth/ guidance and promote the survival of spiral ganglion neurons following electrode insertion trauma.
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Affiliation(s)
- Esperanza Bas
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, United States of America.
| | - Mir R Anwar
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, United States of America
| | - Stefania Goncalves
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, United States of America
| | - Christine T Dinh
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, United States of America
| | - Olena R Bracho
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, United States of America
| | - Juan A Chiossone
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, United States of America
| | - Thomas R Van De Water
- Department of Otolaryngology, University of Miami Miller School of Medicine, Miami, FL, United States of America
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18
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Pharmacokinetics and tissue distribution of neurotrophin 3 after intracochlear delivery. J Control Release 2019; 299:53-63. [PMID: 30790594 DOI: 10.1016/j.jconrel.2019.02.018] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2018] [Revised: 02/11/2019] [Accepted: 02/15/2019] [Indexed: 01/22/2023]
Abstract
Neurotrophin therapy has potential to reverse some forms of hearing loss. However, cochlear pharmacokinetic studies are challenging due to small fluid volumes. Here a radioactive tracer was used to determine neurotrophin-3 retention, distribution and clearance after intracochlear administration. 125I-neurotrophin-3 was injected into guinea pig cochleae using a sealed injection technique comparing dosing volumes, rates and concentrations up to 750 μg/mL. Retention was measured by whole-cochlear gamma counts at five time points while distribution and clearance were assessed by autoradiography. Smaller injection volumes and higher concentrations correlated with higher retention of neurotrophin-3. Distribution of neurotrophin-3 was widespread throughout the cochlear tissue, decreasing in concentration from base to apex. Tissue distribution was non-uniform, with greatest density in cells lining the scala tympani and lower density in neural target tissue. The time constant for clearance of neurotrophin-3 from cochlear tissues was 38 h but neurotrophin-3 remained detectable for at least 2 weeks. Neurotrophin-3 was evident in the semi-circular canals with minor spread to the contralateral cochlea. This study is the first comprehensive evaluation of the disposition profile for a protein therapy in the cochlea. The findings and methods in this study will provide valuable guidance for the development of protein therapies for hearing loss.
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19
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Shepherd RK, Carter PM, Enke YL, Wise AK, Fallon JB. Chronic intracochlear electrical stimulation at high charge densities results in platinum dissolution but not neural loss or functional changes in vivo. J Neural Eng 2018; 16:026009. [PMID: 30523828 DOI: 10.1088/1741-2552/aaf66b] [Citation(s) in RCA: 22] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
Abstract
OBJECTIVE Although there are useful guidelines defining the boundary between damaging and non-damaging electrical stimulation they were derived from acute studies using large surface area electrodes in direct contact with cortical neurons. These parameters are a small subset of the parameters used by neural stimulators. More recently, histological examination of cochleae from patients that were long-term cochlear implant users have shown evidence of particulate platinum (Pt). The pathophysiological effect of Pt within the cochlea is unknown. We examined the response of the cochlea to stimulus levels beyond those regarded as safe, and to evaluate the pathophysiological response of the cochlea following chronic stimulation at charge densities designed to induce Pt corrosion in vivo. APPROACH 19 guinea pigs were systemically deafened and implanted with a cochlear electrode array containing eight Pt electrodes of 0.05, 0.075 or 0.2 mm2 area. Animals were electrically stimulated continuously for 28 d using charge balanced current pulses at charge densities of 400, 267 or 100 µC/cm2/phase. Electrically-evoked auditory brainstem responses (EABRs) were recorded to monitor neural function. On completion of stimulation electrodes were examined using scanning electron microscopy (SEM) and cochleae examined histology. Finally, analysis of Pt was measured using energy dispersive x-ray spectroscopy (EDS) and inductively coupled plasma mass spectrometry (ICP-MS). MAIN RESULTS Compared with unstimulated control electrodes and electrodes stimulated at 100 µC/cm2/phase, stimulation at 267 or 400 µC/cm2/phase resulted in significant Pt corrosion. Cochleae stimulated at these high charge densities contained particulate Pt. The extent of the foreign body response depended on the level of stimulation; cochleae stimulated at 267 or 400 µC/cm2/phase exhibited an extensive tissue response that included a focal region of necrosis close to the electrode. Despite chronic stimulation at high charge densities there was no loss of auditory neurons (ANs) in stimulated cochleae compared with their contralateral controls. Indeed, we report a statistically significant increase in AN density proximal to electrodes stimulated at 267 or 400 µC/cm2/phase. Finally, there was no evidence of a reduction in AN function associated with chronic stimulation at 100, 267 or 400 µC/cm2/phase as evidenced by stable EABR thresholds over the stimulation program. SIGNIFICANCE Chronic electrical stimulation of Pt electrodes at 267 or 400 µC/cm2/phase evoked a vigorous tissue response and produced Pt corrosion products that were located close to the electrode. Despite these changes at the electrode/tissue interface there was no evidence of neural loss or a reduction in neural function.
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Affiliation(s)
- Robert K Shepherd
- Bionics Institute, St Vincent's Hospital, Melbourne, Australia. Medical Bionics Department, The University of Melbourne, Melbourne, Australia
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20
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Moon BS, Lu W, Park HJ. Valproic acid promotes the neuronal differentiation of spiral ganglion neural stem cells with robust axonal growth. Biochem Biophys Res Commun 2018; 503:2728-2735. [PMID: 30119886 DOI: 10.1016/j.bbrc.2018.08.032] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/01/2018] [Accepted: 08/03/2018] [Indexed: 11/28/2022]
Abstract
Hearing loss occurs with the loss of hair cells of the cochlea and subsequent degeneration of spiral ganglion neurons (SGNs). Regeneration of SGNs is a potentially promising therapeutic approach to hearing loss in addition to the use of a cochlear implant (CI), because this device stimulates SGNs directly to restore hearing bypassing the missing hair cells. The presence of SGN-neural stem cells (NSCs) has been reported in adult human and mice. These cells have the potential to become SGNs and thus represent a cellular foundation for regeneration therapies for hearing loss. Valproic acid (VPA) has been shown to influence the neural differentiation of NSCs through multiple signaling pathways involving glycogen synthase kinase3β (GSK3β). Our present study therefore aimed to modulate the neural differentiation potential of SGN-NSCs by treatment with VPA. We here report that a clinically relevant concentration of 1 mM VPA induced the differentiation of basic fibroblast growth factor (bFGF)-treated P1- and P14-SGN-NSCs into neuronal and glial cells, confirmed by neuronal marker (Tuj1 and MAP2) and glial cell marker (GFAP and S100β) detection. VPA-treated cells also promoted much longer neurite outgrowth compared to differentiated cells cultured without bFGF. The effects of VPA on the regulation of differentiation may be related to the activation of the Wnt/β-catenin signaling pathway, but not the inhibition of histone deacetylases (HDACs). We propose that VPA has the potential to convert SGN-NSCs into SGNs and thereby restore hearing when combined with a CI.
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Affiliation(s)
- Byoung-San Moon
- Department of Stem Cell Biology and Regenerative Medicine, Broad Center for Regenerative Medicine and Stem Cell Research, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA; Department of Neurosurgery, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA
| | - Wange Lu
- Department of Stem Cell Biology and Regenerative Medicine, Broad Center for Regenerative Medicine and Stem Cell Research, Keck School of Medicine of the University of Southern California, Los Angeles, CA, USA.
| | - Hong Ju Park
- Department of Otorhinolaryngology-Head and Neck Surgery, Asan Medical Center, University of Ulsan College of Medicine, Seoul, South Korea.
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21
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Mahmoodian-sani MR, Mehri-Ghahfarrokhi A. The potential of miR-183 family expression in inner ear for regeneration, treatment, diagnosis and prognosis of hearing loss. J Otol 2018; 12:55-61. [PMID: 29937838 PMCID: PMC5963458 DOI: 10.1016/j.joto.2017.03.003] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/13/2017] [Revised: 03/22/2017] [Accepted: 03/29/2017] [Indexed: 12/04/2022] Open
Abstract
miRNA-183 family, in normal biology, is expressed in a harmonious and stable manner in the neurosensory organs and cells. Studies have also shown that miRNA-183 family, in different pathways, affects the neurosensory development, maintenance, survival and function. In addition, it has potential neuroprotective effects in response to neurosensory destructive stimulations. miRNA-96 mutation causes hereditary deafness in humans and mice, and therefore affects the inner ear activity and its maintenance. Certain roles have been identified for miR-96 in the maintenance and function of the inner ear. The comparison of the target genes of family-183 in transcriptomes of newborn and adult hair cells shows that hundreds of target genes in this family may affect development and maintenance of the ears. Identifying the genes that are regulated by miRNA-183 family provides researchers with important information about the complex development and environmental regulation of the inner ear, and can offer new approaches to the maintenance and regeneration of hair cells and auditory nerve.
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Affiliation(s)
- Mohammad-Reza Mahmoodian-sani
- Research Center for Molecular Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
- Dept. of Genetics and Molecular Medicine, Hamadan University of Medical Sciences, Hamadan, Iran
- Corresponding author. Fax: +98 381 3330709.
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Tan X, Jahan I, Xu Y, Stock S, Kwan CC, Soriano C, Xiao X, García-Añoveros J, Fritzsch B, Richter CP. Auditory Neural Activity in Congenitally Deaf Mice Induced by Infrared Neural Stimulation. Sci Rep 2018; 8:388. [PMID: 29321651 PMCID: PMC5762820 DOI: 10.1038/s41598-017-18814-9] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2017] [Accepted: 12/11/2017] [Indexed: 11/16/2022] Open
Abstract
To determine whether responses during infrared neural stimulation (INS) result from the direct interaction with spiral ganglion neurons (SGNs), we tested three genetically modified deaf mouse models: Atoh1-cre; Atoh1f/f (Atoh1 conditional knockout, CKO), Atoh1-cre; Atoh1f/kiNeurog1 (Neurog1 knockin, KI), and the Vglut3 knockout (Vglut3−/−) mice. All animals were exposed to tone bursts and clicks up to 107 dB (re 20 µPa) and to INS, delivered with a 200 µm optical fiber. The wavelength (λ) was 1860 nm, the radiant energy (Q) 0-800 µJ/pulse, and the pulse width (PW) 100–500 µs. No auditory responses to acoustic stimuli could be evoked in any of these animals. INS could not evoke auditory brainstem responses in Atoh1 CKO mice but could in Neurog1 KI and Vglut3−/− mice. X-ray micro-computed tomography of the cochleae showed that responses correlated with the presence of SGNs and hair cells. Results in Neurog1 KI mice do not support a mechanical stimulation through the vibration of the basilar membrane, but cannot rule out the direct activation of the inner hair cells. Results in Vglut3−/− mice, which have no synaptic transmission between inner hair cells and SGNs, suggested that hair cells are not required.
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Affiliation(s)
- Xiaodong Tan
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, 320 E. Chicago Avenue, Searle 12-561, Chicago, IL, 60611, USA
| | - Israt Jahan
- Department of Biology, University of Iowa, 129 E. Jefferson Street, Iowa City, IA, 52242, USA
| | - Yingyue Xu
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, 320 E. Chicago Avenue, Searle 12-561, Chicago, IL, 60611, USA
| | - Stuart Stock
- Department of Cell and Molecular Biology, Northwestern University Feinberg School of Medicine, 303 E. Chicago Avenue, Chicago, IL, 60611, USA
| | - Changyow Claire Kwan
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, 320 E. Chicago Avenue, Searle 12-561, Chicago, IL, 60611, USA
| | - Carmen Soriano
- Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL, 60439, USA
| | - Xianghui Xiao
- Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, IL, 60439, USA
| | - Jaime García-Añoveros
- Departments of Anesthesiology, Physiology, and Neurology, Northwestern University Institute for Neuroscience, Ward 10-070, 303 East Chicago Avenue, Chicago, IL, 60611, USA
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, 129 E. Jefferson Street, Iowa City, IA, 52242, USA
| | - Claus-Peter Richter
- Department of Otolaryngology, Northwestern University Feinberg School of Medicine, 320 E. Chicago Avenue, Searle 12-561, Chicago, IL, 60611, USA. .,Department of Biomedical Engineering, Northwestern University, 2145 Sheridan Road, Tech E310, Evanston, IL, 60208, USA. .,The Hugh Knowles Center, Department of Communication Sciences and Disorders, Northwestern University, Frances Searle Building, 2240 Campus Drive, Evanston, IL, 60208, USA.
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Fransson A, Tornøe J, Wahlberg LU, Ulfendahl M. The feasibility of an encapsulated cell approach in an animal deafness model. J Control Release 2017; 270:275-281. [PMID: 29269144 PMCID: PMC5819869 DOI: 10.1016/j.jconrel.2017.12.014] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/24/2017] [Revised: 12/15/2017] [Accepted: 12/17/2017] [Indexed: 01/18/2023]
Abstract
For patients with profound hearing loss a cochlear implant (CI) is the only treatment today. The function of a CI depends in part of the function and survival of the remaining spiral ganglion neurons (SGN). It is well known from animal models that inner ear infusion of neurotrophic factors prevents SGN degeneration and maintains electrical responsiveness in deafened animals. The purpose with this study was to investigate the effects of a novel encapsulated cell (EC) device releasing neurotrophic factors in the deafened guinea pig. The results showed that an EC device releasing glial cell line-derived neurotrophic factor (GDNF) or brain-derived neurotrophic factor (BDNF) implanted for four weeks in deafened guinea pigs significantly preserved the SGNs and maintained their electrical responsiveness. There was a significant difference between BDNF and GDNF in favour of GDNF. This study, demonstrating positive structural and functional effects in the deafened inner ear, suggests that an implanted EC device releasing biologically protective substances offers a feasible approach for treating progressive hearing impairment.
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Affiliation(s)
- Anette Fransson
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden.
| | | | | | - Mats Ulfendahl
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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Gao K, Ding D, Sun H, Roth J, Salvi R. Kanamycin Damages Early Postnatal, but Not Adult Spiral Ganglion Neurons. Neurotox Res 2017; 32:603-613. [PMID: 28656549 PMCID: PMC5711550 DOI: 10.1007/s12640-017-9773-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2017] [Revised: 05/31/2017] [Accepted: 06/13/2017] [Indexed: 01/13/2023]
Abstract
Although aminoglycoside antibiotics such as kanamycin are widely used clinically to treat life-threatening bacterial infections, ototoxicity remains a significant dose-limiting side effect. The prevailing view is that the hair cells are the primary ototoxic target of aminoglycosides and that spiral ganglion neurons begin to degenerate weeks or months after the hair cells have died due to lack of neurotrophic support. To test the early developmental aspects of this issue, we compared kanamycin-induced hair cell and spiral ganglion pathology in rat postnatal day 3 cochlear organotypic cultures with adult whole cochlear explants. In both adult and postnatal day 3 cultures, hair cell damage began at the base of the cochleae and progressed toward the apex in a dose-dependent manner. In postnatal day 3 cultures, spiral ganglion neurons were rapidly destroyed by kanamycin prior to hair cell loss. In contrast, adult spiral ganglion neurons were resistant to kanamycin damage even at the highest concentration, consistent with in vivo models of delayed SGN degeneration. In postnatal day 3 cultures, kanamycin preferentially damaged type I spiral ganglion neurons, whereas type II neurons were resistant. Spiral ganglion degeneration of postnatal day 3 neurons was associated with upregulation of the superoxide radical and caspase-3-mediated cell death. These results show for the first time that kanamycin is toxic to postnatal day 3 spiral ganglion neurons, but not adult neurons.
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Affiliation(s)
- Kelei Gao
- Department of Otolaryngology Head and Neck Surgery, Xiang Ya Hospital, Central South University, Changsha, Hunan, 410013, China
| | - Dalian Ding
- Center for Hearing and Deafness, University at Buffalo, 137 Cary Hall, Buffalo, NY, 14214, USA
| | - Hong Sun
- Department of Otolaryngology Head and Neck Surgery, Xiang Ya Hospital, Central South University, Changsha, Hunan, 410013, China
- Center for Hearing and Deafness, University at Buffalo, 137 Cary Hall, Buffalo, NY, 14214, USA
| | - Jerome Roth
- Department of Audiology and Speech-Language Pathology, Asia University, Taichung, Taiwan
| | - Richard Salvi
- Department of Otolaryngology Head and Neck Surgery, Xiang Ya Hospital, Central South University, Changsha, Hunan, 410013, China.
- Department of Audiology and Speech-Language Pathology, Asia University, Taichung, Taiwan.
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25
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Sale PJP, Uschakov A, Saief T, Rowe DP, Abbott CJ, Luu CD, Hampson AJ, O'Leary SJ, Sly DJ. Cannula-based drug delivery to the guinea pig round window causes a lasting hearing loss that may be temporarily mitigated by BDNF. Hear Res 2017; 356:104-115. [PMID: 29089185 DOI: 10.1016/j.heares.2017.10.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 09/22/2017] [Accepted: 10/11/2017] [Indexed: 01/30/2023]
Abstract
Sustained local delivery of drugs to the inner ear may be required for future regenerative and protective strategies. The round window is surgically accessible and a promising delivery route. To be viable, a delivery system should not cause hearing loss. This study determined the effect on hearing of placing a drug-delivery microcatheter on to the round window, and delivering either artificial perilymph (AP) or brain-derived neurotrophic factor (BDNF) via this catheter with a mini-osmotic pump. Auditory brainstem responses (ABRs) were monitored for 4 months after surgery, while the AP or BDNF was administered for the first month. The presence of the microcatheter - whether dry or when delivering AP or BDNF for 4 weeks - was associated with an increase in ABR thresholds of up to 15 dB, 16 weeks after implantation. This threshold shift was, in part, delayed by the delivery of BDNF. We conclude that the chronic presence of a microcatheter in the round window niche causes hearing loss, and that this is exacerbated by delivery of AP, and ameliorated temporarily by delivery of BDNF.
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Affiliation(s)
- Phillip J P Sale
- Otolaryngology, Department of Surgery, University of Melbourne, East Melbourne 3002, Australia
| | - Aaron Uschakov
- Otolaryngology, Department of Surgery, University of Melbourne, East Melbourne 3002, Australia
| | - Tasfia Saief
- Otolaryngology, Department of Surgery, University of Melbourne, East Melbourne 3002, Australia
| | - David P Rowe
- Otolaryngology, Department of Surgery, University of Melbourne, East Melbourne 3002, Australia
| | - Carla J Abbott
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne 3002, Australia; Ophthalmology, Department of Surgery, University of Melbourne, Parkville 3010, Australia
| | - Chi D Luu
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, East Melbourne 3002, Australia; Ophthalmology, Department of Surgery, University of Melbourne, Parkville 3010, Australia
| | - Amy J Hampson
- Otolaryngology, Department of Surgery, University of Melbourne, East Melbourne 3002, Australia
| | - Stephen J O'Leary
- Otolaryngology, Department of Surgery, University of Melbourne, East Melbourne 3002, Australia.
| | - David J Sly
- Otolaryngology, Department of Surgery, University of Melbourne, East Melbourne 3002, Australia; Department of Health and Medical Sciences, Swinburne University of Technology, Hawthorn 3122, Australia
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26
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Time-dependent activity of primary auditory neurons in the presence of neurotrophins and antibiotics. Hear Res 2017; 350:122-132. [DOI: 10.1016/j.heares.2017.04.014] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Revised: 03/16/2017] [Accepted: 04/23/2017] [Indexed: 12/19/2022]
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27
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Schendzielorz P, Rak K, Radeloff K, Völker J, Gehrke T, Scherzad A, Kleinsasser N, Hagen R, Radeloff A. A polydopamine peptide coating enables adipose-derived stem cell growth on the silicone surface of cochlear implant electrode arrays. J Biomed Mater Res B Appl Biomater 2017. [PMID: 28639367 DOI: 10.1002/jbm.b.33947] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
The simultaneous application of neurotrophic factors with cochlear implantation is proposed to enhance the bioelectrical interface between electrodes and auditory neurons, and thus improve speech intelligibility in patients with cochlear implants (CIs). In cell-based approaches, the goal is to colonize CIs with cells producing neurotrophic factors. This study aims to evaluate whether a polydopamine (PD) functionalization of the hydrophobic silicone surface of the electrode carrier enables colonization of adipose-derived stem cells known to deliver neurotrophic factors. Surface characteristics of PD-coated silicone samples and electrode carriers were determined, and the proliferation and viability of adipose-derived stem cells (ASCs) on these surfaces were subsequently analyzed. A homogenous PD coating and cell growth with regular morphology was observed on coated silicone samples and electrode arrays. Hydrophilicity and cell viability was significantly enhanced by PD surface modification. Insertion forces of coated electrode arrays did not increase compared with untreated CIs. Hence, PD coating of the silicone surface of CIs might allow for sufficient colonization with ASCs as a continuous source of neurotrophic factors. © 2017 Wiley Periodicals, Inc. J Biomater Res Part A: 106B: 1431-1438, 2018.
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Affiliation(s)
- Philipp Schendzielorz
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic, and Reconstructive Head and Neck Surgery, Comprehensive Hearing Center, University of Wuerzburg, Josef-Schneider-Straße 11, 97080, Wuerzburg, Germany
| | - Kristen Rak
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic, and Reconstructive Head and Neck Surgery, Comprehensive Hearing Center, University of Wuerzburg, Josef-Schneider-Straße 11, 97080, Wuerzburg, Germany
| | - Katrin Radeloff
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic, and Reconstructive Head and Neck Surgery, Comprehensive Hearing Center, University of Wuerzburg, Josef-Schneider-Straße 11, 97080, Wuerzburg, Germany
| | - Johannes Völker
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic, and Reconstructive Head and Neck Surgery, Comprehensive Hearing Center, University of Wuerzburg, Josef-Schneider-Straße 11, 97080, Wuerzburg, Germany
| | - Thomas Gehrke
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic, and Reconstructive Head and Neck Surgery, Comprehensive Hearing Center, University of Wuerzburg, Josef-Schneider-Straße 11, 97080, Wuerzburg, Germany
| | - Agmal Scherzad
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic, and Reconstructive Head and Neck Surgery, Comprehensive Hearing Center, University of Wuerzburg, Josef-Schneider-Straße 11, 97080, Wuerzburg, Germany
| | - Norbert Kleinsasser
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic, and Reconstructive Head and Neck Surgery, Comprehensive Hearing Center, University of Wuerzburg, Josef-Schneider-Straße 11, 97080, Wuerzburg, Germany
| | - Rudolf Hagen
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic, and Reconstructive Head and Neck Surgery, Comprehensive Hearing Center, University of Wuerzburg, Josef-Schneider-Straße 11, 97080, Wuerzburg, Germany
| | - Andreas Radeloff
- Department of Oto-Rhino-Laryngology, Head and Neck Surgery, Carl von Ossietzky-University, Oldenburg, Germany
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28
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Encapsulated cell device approach for combined electrical stimulation and neurotrophic treatment of the deaf cochlea. Hear Res 2017; 350:110-121. [PMID: 28463804 DOI: 10.1016/j.heares.2017.04.013] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2016] [Revised: 03/15/2017] [Accepted: 04/23/2017] [Indexed: 12/21/2022]
Abstract
Profound hearing impairment can be overcome by electrical stimulation (ES) of spiral ganglion neurons (SGNs) via a cochlear implant (CI). Thus, SGN survival is critical for CI efficacy. Application of glial cell line-derived neurotrophic factor (GDNF) has been shown to reduce SGN degeneration following deafness. We tested a novel method for local, continuous GDNF-delivery in combination with ES via a CI. The encapsulated cell (EC) device contained a human ARPE-19 cell-line, genetically engineered for secretion of GDNF. In vitro, GDNF delivery was stable during ES delivered via a CI. In the chronic in vivo part, cats were systemically deafened and unilaterally implanted into the scala tympani with a CI and an EC device, which they wore for six months. The implantation of control devices (same cell-line not producing GDNF) had no negative effect on SGN survival. GDNF application without ES led to an unexpected reduction in SGN survival, however, the combination of GDNF with initial, short-term ES resulted in a significant protection of SGNs. A tight fibrous tissue formation in the scala tympani of the GDNF-only group is thought to be responsible for the increased SGN degeneration, due to mechanisms related to an aggravated foreign body response. Furthermore, the fibrotic encapsulation of the EC device led to cell death or cessation of GDNF release within the EC device during the six months in vivo. In both in vitro and in vivo, fibrosis was reduced by CI stimulation, enabling the neuroprotective effect of the combined treatment. Thus, fibrous tissue growth limits treatment possibilities with an EC device. For a stable and successful long-term neurotrophic treatment of the SGN via EC devices in human CI users, it would be necessary to make changes in the treatment approach (provision of anti-inflammatories), the EC device surface (reduced cell adhesion) and the ES (initiation prior to fibrosis formation).
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29
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Hu H, Ye B, Zhang L, Wang Q, Liu Z, Ji S, Liu Q, Lv J, Ma Y, Xu Y, Wu H, Huang F, Xiang M. Efr3a Insufficiency Attenuates the Degeneration of Spiral Ganglion Neurons after Hair Cell Loss. Front Mol Neurosci 2017; 10:86. [PMID: 28424585 PMCID: PMC5372784 DOI: 10.3389/fnmol.2017.00086] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2016] [Accepted: 03/10/2017] [Indexed: 01/19/2023] Open
Abstract
Sensorineural hearing loss (SNHL) is caused by an irreversible impairment of cochlear hair cells and subsequent progressive degeneration of spiral ganglion neurons (SGNs). Eighty-five requiring 3 (Efr3) is a plasma membrane protein conserved from yeast to human, and knockout of Efr3a was reported to facilitate the survival of hippocampal newborn neurons in adult mice. Previously, we found Efr3a expression in the auditory neural pathway is upregulated soon after the destruction of hair cells. Here we conducted a time-course analysis of drug-caused damage to hearing ability, hair cells and SGNs in Efr3a knocking down mice (Efr3a−/+, Efr3a KD) and their wild type littermates. Functional examination showed that both groups of mice suffered from serious hearing loss with a higher level of severity in wild type (WT) mice. Morphologic observation following drugs administration showed that both WT and Efr3a KD mice went through progressive loss of hair cells and SGNs, in association with degenerative changes in the perikarya, intracellular organelles, cell body conformation in SGNs, and the changes of SGNs in WT mice were more severe than in Efr3a KD mice. These beneficial effects of Efr3a KD could be ascribed to an increase in the expression of some neurotrophic factors and their receptors in Efr3a KD mice. Our results indicate that Efr3a insufficiency suppresses drug-caused SNHL neurodegeneration in association with an increase in the expression of some neurotrophic factors and their receptors, which may be targeted in the treatment of neurodegeneration.
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Affiliation(s)
- Haixia Hu
- Department of Otolaryngology and Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of MedicineShanghai, China.,Shanghai Key Laboratory of Translational Medicine on Ear and Nose DiseasesShanghai, China.,Ear Institute, Shanghai Jiao Tong University School of MedicineShanghai, China
| | - Bin Ye
- Department of Otolaryngology and Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of MedicineShanghai, China.,Shanghai Key Laboratory of Translational Medicine on Ear and Nose DiseasesShanghai, China.,Ear Institute, Shanghai Jiao Tong University School of MedicineShanghai, China
| | - Le Zhang
- Shanghai Advanced Research Institute, University of Chinese Academy of Sciences, Chinese Academy of SciencesShanghai, China
| | - Quan Wang
- Department of Otolaryngology and Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of MedicineShanghai, China.,Shanghai Key Laboratory of Translational Medicine on Ear and Nose DiseasesShanghai, China.,Ear Institute, Shanghai Jiao Tong University School of MedicineShanghai, China
| | - Zhiwei Liu
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing UniversityNanjing, China
| | - Suying Ji
- Institute of Neuroscience and State Key Laboratory of Neuroscience, Institute of Biological Science, Chinese Academy of SciencesShanghai, China
| | - Qiuju Liu
- Institute of Neuroscience and State Key Laboratory of Neuroscience, Institute of Biological Science, Chinese Academy of SciencesShanghai, China
| | - Jingrong Lv
- Department of Otolaryngology and Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of MedicineShanghai, China
| | - Yan Ma
- Department of Otolaryngology and Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of MedicineShanghai, China
| | - Ying Xu
- MOE Key Laboratory of Model Animal for Disease Study, Model Animal Research Center, Nanjing UniversityNanjing, China
| | - Hao Wu
- Shanghai Key Laboratory of Translational Medicine on Ear and Nose DiseasesShanghai, China.,Ear Institute, Shanghai Jiao Tong University School of MedicineShanghai, China
| | - Fude Huang
- Shanghai Advanced Research Institute, University of Chinese Academy of Sciences, Chinese Academy of SciencesShanghai, China.,Institute of Neuroscience and State Key Laboratory of Neuroscience, Institute of Biological Science, Chinese Academy of SciencesShanghai, China
| | - Mingliang Xiang
- Department of Otolaryngology and Head and Neck Surgery, Xinhua Hospital, Shanghai Jiao Tong University School of MedicineShanghai, China.,Shanghai Key Laboratory of Translational Medicine on Ear and Nose DiseasesShanghai, China.,Ear Institute, Shanghai Jiao Tong University School of MedicineShanghai, China
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30
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Ramamurthy P, White JB, Yull Park J, Hume RI, Ebisu F, Mendez F, Takayama S, Barald KF. Concomitant differentiation of a population of mouse embryonic stem cells into neuron-like cells and schwann cell-like cells in a slow-flow microfluidic device. Dev Dyn 2017; 246:7-27. [PMID: 27761977 PMCID: PMC5159187 DOI: 10.1002/dvdy.24466] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 09/16/2016] [Accepted: 09/30/2016] [Indexed: 12/14/2022] Open
Abstract
BACKGROUND To send meaningful information to the brain, an inner ear cochlear implant (CI) must become closely coupled to as large and healthy a population of remaining spiral ganglion neurons (SGN) as possible. Inner ear gangliogenesis depends on macrophage migration inhibitory factor (MIF), a directionally attractant neurotrophic cytokine made by both Schwann and supporting cells (Bank et al., 2012). MIF-induced mouse embryonic stem cell (mESC)-derived "neurons" could potentially substitute for lost or damaged SGN. mESC-derived "Schwann cells" produce MIF, as do all Schwann cells (Huang et al., a; Roth et al., 2007; Roth et al., 2008) and could attract SGN to a "cell-coated" implant. RESULTS Neuron- and Schwann cell-like cells were produced from a common population of mESCs in an ultra-slow-flow microfluidic device. As the populations interacted, "neurons" grew over the "Schwann cell" lawn, and early events in myelination were documented. Blocking MIF on the Schwann cell side greatly reduced directional neurite outgrowth. MIF-expressing "Schwann cells" were used to coat a CI: Mouse SGN and MIF-induced "neurons" grew directionally to the CI and to a wild-type but not MIF-knockout organ of Corti explant. CONCLUSIONS Two novel stem cell-based approaches for treating the problem of sensorineural hearing loss are described. Developmental Dynamics 246:7-27, 2017. © 2016 Wiley Periodicals, Inc.
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Affiliation(s)
- Poornapriya Ramamurthy
- Department of Biomedical Engineering, College of Engineering, University of Michigan, Ann Arbor, Michigan
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan
| | - Joshua B White
- Department of Biomedical Engineering, College of Engineering, University of Michigan, Ann Arbor, Michigan
| | - Joong Yull Park
- School of Mechanical Engineering, College of Engineering, Chung-Ang University, Seoul, Republic of Korea
| | - Richard I Hume
- Department of Molecular, Cellular, and Developmental Biology, University of Michigan, Ann Arbor, Michigan
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, Michigan
| | - Fumi Ebisu
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan
| | - Flor Mendez
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan
| | - Shuichi Takayama
- Department of Biomedical Engineering, College of Engineering, University of Michigan, Ann Arbor, Michigan
| | - Kate F Barald
- Department of Biomedical Engineering, College of Engineering, University of Michigan, Ann Arbor, Michigan
- Department of Cell and Developmental Biology, University of Michigan Medical School, Ann Arbor, Michigan
- Neuroscience Graduate Program, University of Michigan, Ann Arbor, Michigan
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31
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Li D, Sun J, Zhao L, Guo W, Sun W, Yang S. Aminoglycoside Increases Permeability of Osseous Spiral Laminae of Cochlea by Interrupting MMP-2 and MMP-9 Balance. Neurotox Res 2016; 31:348-357. [PMID: 28005182 DOI: 10.1007/s12640-016-9689-2] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2016] [Revised: 12/10/2016] [Accepted: 12/12/2016] [Indexed: 12/20/2022]
Abstract
The spiral ganglion neurons (SGNs) located in the Rosenthal's canal of cochlea are essential target for cochlear implant. Previous studies found that the canaliculi perforantes, small pores on the surface of the osseous spiral lamina (OSL) of the scala tympanic (ST) of cochlea, may provide communication between the cochlear perilymph and SGNs. In this study, we found that chronic treatment of aminoglycosides antibiotics, which is well known to cause sensory cell damage in the cochlea, induced significant damage of bone lining cells on the OSLs and increased the permeability of the Rosenthal's canal. The pores among the bone lining cells became significantly wider after chronic treatment of amikacin (100 mg/kg/day for 3-7 days). Injection of Evans Blue in the ST resulted in significant increase in its migration in the modulus in the amikacin-treated cochlea compared to the control ears, suggesting increased permeability of these passages. Treatment of amikacin with oxytetracycline, an inhibitor of matrix metalloproteases (MMPs), significantly reduced the amount of dye migrated from the ST to the modiolus. These results suggest that amikacin enhanced the permeability between the ST and SGNs by increasing MMPs. Aggregating the permeability of the bone lining cells on the OSLs may benefit gene and stem cell delivery to the SGNs in the cochlea.
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Affiliation(s)
- Dengke Li
- Department of Otolaryngology, Head and Neck Surgery, Institute of Otolaryngology of PLA, Chinese PLA General Hospital, Beijing, 100853, People's Republic of China
| | - Jianhe Sun
- Department of Otolaryngology, Head and Neck Surgery, Institute of Otolaryngology of PLA, Chinese PLA General Hospital, Beijing, 100853, People's Republic of China
| | - Lidong Zhao
- Department of Otolaryngology, Head and Neck Surgery, Institute of Otolaryngology of PLA, Chinese PLA General Hospital, Beijing, 100853, People's Republic of China
| | - Weiwei Guo
- Department of Otolaryngology, Head and Neck Surgery, Institute of Otolaryngology of PLA, Chinese PLA General Hospital, Beijing, 100853, People's Republic of China
| | - Wei Sun
- Department of Communicative Disorders and Sciences, Center for Hearing and Deafness, the State University of New York at Buffalo, Buffalo, New York, 14214, USA
| | - Shiming Yang
- Department of Otolaryngology, Head and Neck Surgery, Institute of Otolaryngology of PLA, Chinese PLA General Hospital, Beijing, 100853, People's Republic of China.
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32
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Wise AK, Tan J, Wang Y, Caruso F, Shepherd RK. Improved Auditory Nerve Survival with Nanoengineered Supraparticles for Neurotrophin Delivery into the Deafened Cochlea. PLoS One 2016; 11:e0164867. [PMID: 27788219 PMCID: PMC5082918 DOI: 10.1371/journal.pone.0164867] [Citation(s) in RCA: 47] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/24/2016] [Accepted: 10/03/2016] [Indexed: 11/23/2022] Open
Abstract
Cochlear implants electrically stimulate spiral ganglion neurons (SGNs) in order to provide speech cues to severe-profoundly deaf patients. In normal hearing cochleae the SGNs depend on endogenous neurotrophins secreted by sensory cells in the organ of Corti for survival. SGNs gradually degenerate following deafness and consequently there is considerable interest in developing clinically relevant strategies to provide exogenous neurotrophins to preserve SGN survival. The present study investigated the safety and efficacy of a drug delivery system for the cochlea using nanoengineered silica supraparticles. In the present study we delivered Brain-derived neurotrophic factor (BDNF) over a period of four weeks and evaluated SGN survival as a measure of efficacy. Supraparticles were bilaterally implanted into the basal turn of cochleae in profoundly deafened guinea pigs. One ear received BDNF-loaded supraparticles and the other ear control (unloaded) supraparticles. After one month of treatment the cochleae were examined histologically. There was significantly greater survival of SGNs in cochleae that received BDNF supraparticles compared to the contralateral control cochleae (repeated measures ANOVA, p = 0.009). SGN survival was observed over a wide extent of the cochlea. The supraparticles were well tolerated within the cochlea with a tissue response that was localised to the site of implantation in the cochlear base. Although mild, the tissue response was significantly greater in cochleae treated with BDNF supraparticles compared to the controls (repeated measures ANOVA, p = 0.003). These data support the clinical potential of this technology particularly as the supraparticles can be loaded with a variety of therapeutic drugs.
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Affiliation(s)
- Andrew K. Wise
- The Bionics Institute, 384–388 Albert Street, East Melbourne, Melbourne, Australia
- The Department of Medical Bionics, University of Melbourne, Melbourne, Australia
- Department of Otolaryngology, University of Melbourne, Melbourne, Australia
- * E-mail:
| | - Justin Tan
- Department of Otolaryngology, University of Melbourne, Melbourne, Australia
| | - Yajun Wang
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, and the Department of Chemical and Biomolecular Engineering, the University of Melbourne, Melbourne, Australia
| | - Frank Caruso
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, and the Department of Chemical and Biomolecular Engineering, the University of Melbourne, Melbourne, Australia
| | - Robert K. Shepherd
- The Bionics Institute, 384–388 Albert Street, East Melbourne, Melbourne, Australia
- The Department of Medical Bionics, University of Melbourne, Melbourne, Australia
- Department of Otolaryngology, University of Melbourne, Melbourne, Australia
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33
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Wiegner A, Wright CG, Vollmer M. Multichannel cochlear implant for selective neuronal activation and chronic use in the free-moving Mongolian gerbil. J Neurosci Methods 2016; 273:40-54. [PMID: 27519925 DOI: 10.1016/j.jneumeth.2016.08.006] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 08/05/2016] [Accepted: 08/08/2016] [Indexed: 12/18/2022]
Abstract
BACKGROUND Animal models for chronic multichannel cochlear implant stimulation and selective neuronal activation contribute to a better understanding of auditory signal processing and central neural plasticity. NEW METHOD This paper describes the design and surgical implantation of a multichannel cochlear implant (CI) system for chronic use in the free-moving gerbil. For chronic stimulation, adult-deafened gerbils were connected to a multichannel commutator that allowed low resistance cable rotation and stable electric connectivity to the current source. RESULTS Despite the small scale of the gerbil cochlea and auditory brain regions, final electrophysiological mapping experiments revealed selective and tonotopically organized neuronal activation in the auditory cortex. Contact impedances and electrically evoked auditory brainstem responses were stable over several weeks demonstrating the long-term integrity of the implant and the efficacy of the stimulation. COMPARISON WITH EXISTING METHODS Most animal models on multichannel signal processing and stimulation-induced plasticity are limited to larger animals such as ferrets, cats and primates. Multichannel CI stimulation in the free-moving rodent and evidence for selective neuronal activation in gerbil auditory cortex have not been previously reported. CONCLUSIONS Overall, our results show that the gerbil is a robust rodent model for selective and tonotopically organized multichannel CI stimulation. We anticipate that this model provides a useful tool to develop and test both passive stimulation and behavioral training strategies for plastic reorganization and restoration of degraded unilateral and bilateral central auditory signal processing in the hearing impaired and deaf central auditory system.
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Affiliation(s)
- Armin Wiegner
- Comprehensive Hearing Center, University Hospital Wuerzburg, Josef-Schneider-Str. 11, 97080 Wuerzburg, Germany.
| | - Charles G Wright
- Department of Otolaryngology-Head and Neck Surgery, Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, TX 75390, United States.
| | - Maike Vollmer
- Comprehensive Hearing Center, University Hospital Wuerzburg, Josef-Schneider-Str. 11, 97080 Wuerzburg, Germany.
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34
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Fransson A, Ulfendahl M. Structural changes in the inner ear over time studied in the experimentally deafened guinea pig. J Neurosci Res 2016; 95:869-875. [PMID: 27400677 PMCID: PMC5297876 DOI: 10.1002/jnr.23824] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/31/2016] [Revised: 06/03/2016] [Accepted: 06/17/2016] [Indexed: 11/24/2022]
Abstract
Today a cochlear implant (CI) may significantly restore auditory function, even for people with a profound hearing loss. Because the efficacy of a CI is believed to depend mainly on the remaining population of spiral ganglion neurons (SGNs), it is important to understand the timeline of the degenerative process of the auditory neurons following deafness. Guinea pigs were transtympanically deafened with neomycin, verified by recording auditory brainstem responses (ABRs), and then sacrificed at different time points. Loss of SGNs as well as changes in cell body and nuclear volume were estimated. To study the effect of delayed treatment, a group of animals that had been deaf for 12 weeks was implanted with a stimulus electrode mimicking a CI, after which they received a 4‐week treatment with glial cell‐derived neurotrophic factor (GDNF). The electrical responsiveness of the SGNs was measured by recording electrically evoked ABRs. There was a rapid degeneration during the first 7 weeks, shown as a significant reduction of the SGN population. The degenerative process then slowed, and there was no difference in the amount of remaining neurons between weeks 7 and 18. © 2016 The Authors Journal of Neuroscience Research Published by Wiley Periodicals, Inc.
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Affiliation(s)
- Anette Fransson
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
| | - Mats Ulfendahl
- Department of Neuroscience, Karolinska Institutet, Stockholm, Sweden
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Firing frequency and entrainment maintained in primary auditory neurons in the presence of combined BDNF and NT3. Sci Rep 2016; 6:28584. [PMID: 27335179 PMCID: PMC4917828 DOI: 10.1038/srep28584] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2015] [Accepted: 06/07/2016] [Indexed: 12/16/2022] Open
Abstract
Primary auditory neurons rely on neurotrophic factors for development and survival. We previously determined that exposure to brain-derived neurotrophic factor (BDNF) and neurotrophin-3 (NT3) alters the activity of hyperpolarization-activated currents (Ih) in this neuronal population. Since potassium channels are sensitive to neurotrophins, and changes in Ih are often accompanied by a shift in voltage-gated potassium currents (IK), this study examined IK with exposure to both BDNF and NT3 and the impact on firing entrainment during high frequency pulse trains. Whole-cell patch-clamp recordings revealed significant changes in action potential latency and duration, but no change in firing adaptation or total outward IK. Dendrotoxin-I (DTX-I), targeting voltage-gated potassium channel subunits KV1.1 and KV1.2, uncovered an increase in the contribution of DTX-I sensitive currents with exposure to neurotrophins. No difference in Phrixotoxin-1 (PaTX-1) sensitive currents, mediated by KV4.2 and KV4.3 subunits, was observed. Further, no difference was seen in firing entrainment. These results show that combined BDNF and NT3 exposure influences the contribution of KV1.1 and KV1.2 to the low voltage-activated potassium current (IKL). Whilst this is accompanied by a shift in spike latency and duration, both firing frequency and entrainment to high frequency pulse trains are preserved.
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Jin Y, Lyu AR, Park SJ, Xu J, Cui J, Sohn KC, Hur GM, Jin Y, Park YH. Early Postnatal NT-3 Gene Delivery Enhances Hearing Acquisition in the Developmental Period. Laryngoscope 2016; 126:E379-E385. [DOI: 10.1002/lary.26130] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/22/2016] [Revised: 05/07/2016] [Accepted: 05/11/2016] [Indexed: 12/18/2022]
Affiliation(s)
- Yongde Jin
- Department of Otolaryngology-Head and Neck Surgery; Yanbian University Hospital; Yanji China
| | - Ah-Ra Lyu
- Department of Otolaryngology-Head and Neck Surgery , College of Medicine; Chungnam National University; Daejeon Republic of Korea
- Department of Medical Science; Chungnam National University; Daejeon Republic of Korea
| | - Sung-Jae Park
- Department of Otolaryngology-Head and Neck Surgery , College of Medicine; Chungnam National University; Daejeon Republic of Korea
| | - Jun Xu
- Department of Otolaryngology-Head and Neck Surgery; Yanbian University Hospital; Yanji China
- Department of Otolaryngology-Head and Neck Surgery , College of Medicine; Chungnam National University; Daejeon Republic of Korea
| | - Jie Cui
- Department of Otolaryngology-Head and Neck Surgery; Yanbian University Hospital; Yanji China
| | - Kyung-Cheol Sohn
- Department of Dermatology , College of Medicine; Chungnam National University; Daejeon Republic of Korea
| | - Gang Min Hur
- Department of Pharmacology , College of Medicine; Chungnam National University; Daejeon Republic of Korea
| | - Yulian Jin
- Department of Otolaryngology-Head and Neck Surgery; Yanbian University Hospital; Yanji China
| | - Yong-Ho Park
- Department of Otolaryngology-Head and Neck Surgery , College of Medicine; Chungnam National University; Daejeon Republic of Korea
- Brain Research Institute , College of Medicine; Chungnam National University; Daejeon Republic of Korea
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Charge-balanced biphasic electrical stimulation inhibits neurite extension of spiral ganglion neurons. Neurosci Lett 2016; 624:92-9. [DOI: 10.1016/j.neulet.2016.04.069] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2016] [Revised: 04/17/2016] [Accepted: 04/28/2016] [Indexed: 11/23/2022]
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Suzuki J, Corfas G, Liberman MC. Round-window delivery of neurotrophin 3 regenerates cochlear synapses after acoustic overexposure. Sci Rep 2016; 6:24907. [PMID: 27108594 PMCID: PMC4842978 DOI: 10.1038/srep24907] [Citation(s) in RCA: 147] [Impact Index Per Article: 18.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2016] [Accepted: 04/04/2016] [Indexed: 12/27/2022] Open
Abstract
In acquired sensorineural hearing loss, such as that produced by noise or aging, there can be massive loss of the synaptic connections between cochlear sensory cells and primary sensory neurons, without loss of the sensory cells themselves. Because the cell bodies and central projections of these cochlear neurons survive for months to years, there is a long therapeutic window in which to re-establish functional connections and improve hearing ability. Here we show in noise-exposed mice that local delivery of neurotrophin-3 (NT-3) to the round window niche, 24 hours after an exposure that causes an immediate loss of up to 50% loss of synapses in the cochlear basal region, can regenerate pre- and post-synaptic elements at the hair cell / cochlear nerve interface. This synaptic regeneration, as documented by confocal microscopy of immunostained cochlear sensory epithelia, was coupled with a corresponding functional recovery, as seen in the suprathreshold amplitude of auditory brainstem response Wave 1. Cochlear delivery of neurotrophins in humans is likely achievable as an office procedure via transtympanic injection, making our results highly significant in a translational context.
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Affiliation(s)
- Jun Suzuki
- Department of Otology and Laryngology, Harvard Medical School, Boston MA 02115, USA.,Eaton-Peabody Laboratories, Massachusetts Eye &Ear Infirmary, Boston MA 02114, USA.,Department of Otorhinolaryngology-Head and Neck Surgery, Tohoku University Graduate School of Medicine, Sendai, Miyagi 980-8574, Japan
| | - Gabriel Corfas
- Kresge Hearing Research Institute and Department of Otolaryngology-Head and Neck Surgery, University of Michigan, Ann Arbor, MI, USA
| | - M Charles Liberman
- Department of Otology and Laryngology, Harvard Medical School, Boston MA 02115, USA.,Eaton-Peabody Laboratories, Massachusetts Eye &Ear Infirmary, Boston MA 02114, USA
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Quesnel AM, Nakajima HH, Rosowski JJ, Hansen MR, Gantz BJ, Nadol JB. Delayed loss of hearing after hearing preservation cochlear implantation: Human temporal bone pathology and implications for etiology. Hear Res 2016; 333:225-234. [PMID: 26341474 PMCID: PMC4775460 DOI: 10.1016/j.heares.2015.08.018] [Citation(s) in RCA: 118] [Impact Index Per Article: 14.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/11/2015] [Revised: 08/04/2015] [Accepted: 08/27/2015] [Indexed: 11/23/2022]
Abstract
After initially successful preservation of residual hearing with cochlear implantation, some patients experience subsequent delayed hearing loss. The etiology of such delayed hearing loss is unknown. Human temporal bone pathology is critically important in investigating the etiology, and directing future efforts to maximize long term hearing preservation in cochlear implant patients. Here we present the temporal bone pathology from a patient implanted during life with an Iowa/Nucleus Hybrid S8 implant, with initially preserved residual hearing and subsequent hearing loss. Both temporal bones were removed for histologic processing and evaluated. Complete clinical and audiologic records were available. He had bilateral symmetric high frequency severe to profound hearing loss prior to implantation. Since he was implanted unilaterally, the unimplanted ear was presumed to be representative of the pre-implantation pathology related to his hearing loss. The implanted and contralateral unimplanted temporal bones both showed complete degeneration of inner hair cells and outer hair cells in the basal half of the cochleae, and only mild patchy loss of inner hair cells and outer hair cells in the apical half. The total spiral ganglion neuron counts were similar in both ears: 15,138 (56% of normal for age) in the unimplanted right ear and 13,722 (51% of normal for age) in the implanted left ear. In the basal turn of the implanted left cochlea, loose fibrous tissue and new bone formation filled the scala tympani, and part of the scala vestibuli. Delayed loss of initially preserved hearing after cochlear implantation was not explained by additional post-implantation degeneration of hair cells or spiral ganglion neurons in this patient. Decreased compliance at the round window and increased damping in the scala tympani due to intracochlear fibrosis and new bone formation might explain part of the post-implantation hearing loss. Reduction of the inflammatory and immune response to cochlear implantation may lead to better long term hearing preservation post-implantation.
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Affiliation(s)
- Alicia M Quesnel
- Department of Otology and Laryngology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, USA.
| | - Hideko Heidi Nakajima
- Department of Otology and Laryngology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, USA.
| | - John J Rosowski
- Department of Otology and Laryngology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, USA.
| | - Marlan R Hansen
- University of Iowa Hospitals and Clinics, Department of Otolaryngology, 200 Hawkins Drive, Iowa City, IA 52242-1078, USA.
| | - Bruce J Gantz
- University of Iowa Hospitals and Clinics, Department of Otolaryngology, 200 Hawkins Drive, Iowa City, IA 52242-1078, USA.
| | - Joseph B Nadol
- Department of Otology and Laryngology, Harvard Medical School, Massachusetts Eye and Ear Infirmary, 243 Charles Street, Boston, MA 02114, USA.
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Fabrication and evaluation of an improved polymer-based cochlear electrode array for atraumatic insertion. Biomed Microdevices 2016; 17:32. [PMID: 25681972 DOI: 10.1007/s10544-015-9941-1] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
Abstract
An atraumatic cochlear electrode array has become indispensable to high-performance cochlear implants such as electric acoustic stimulation (EAS), wherein the preservation of residual hearing is significant. For an atraumatic implantation, we propose and demonstrate a new improved design of a cochlear electrode array based on liquid crystal polymer (LCP), which can be fabricated by precise batch processes and a thermal lamination process, in contrast to conventional wire-based cochlear electrode arrays. Using a thin-film process of LCP-film-mounted silicon wafer and thermal press lamination, we devise a multi-layered structure with variable layers of LCP films to achieve a sufficient degree of basal rigidity and a flexible tip. A peripheral blind via and self-aligned silicone elastomer molding process can reduce the width of the array. Measuring the insertion and extraction forces in a human scala tympani model, we investigate five human temporal bone insertion trials and record electrically evoked auditory brainstem responses (EABR) acutely in a guinea pig model. The diameters of the finalized electrode arrays are 0.3 mm (tip) and 0.75 mm (base). The insertion force with a displacement of 8 mm from a round window and the maximum extraction force are 2.4 mN and 34.0 mN, respectively. The electrode arrays can be inserted from 360° to 630° without trauma at the basal turn. The EABR data confirm the efficacy of the array. A new design of LCP-based cochlear electrode array for atraumatic implantation is fabricated. Verification indicates that foretells the development of an atraumatic cochlear electrode array and clinical implant.
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Sameer Mallick A, Qureishi A, Pearson R, O'Donoghue G. Neurotrophins and cochlear implants: a solution to sensorineural deafness? Cochlear Implants Int 2015; 14:158-64. [PMID: 22889496 DOI: 10.1179/1754762812y.0000000013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
OBJECTIVES To review current trends for treating sensorineural deafness by enhancing spiral ganglion neuron (SGN) survival using neurotrophins combined with cochlear implants and identify areas for future research and development. METHODS A literature search was undertaken on PubMed and Google scholar using terms: neurotrophins, cochlear implants (CIs), and sensorineural to identify the most recent and significant publications. The abstracts were read to identify relevant papers; these were accessed in full and analysed for this review. RESULTS Neurotrophins have a known role in cochlear development and the maintenance of SGNs. So far experiments using osmotic pumps to deliver neurotrophins have been successful for short-term enhanced survival of SGN's following aminoglycoside ototoxicity in animal models. They have demonstrated the re-sprouting of radial nerve fibres from SGN's towards the source of delivery. In addition electrical stimulation, gene and cell-based therapy have increased SGN survival to varying degrees. DISCUSSION Osmotic pumps carry a high risk of infection therefore CIs coated in a drug containing polymer or hydrogel are a realistic alternative for sustained delivery of neurotrophins. Increased SGN survival combined with neuronal re-growth raises the possibility for CIs to stimulate discrete SGN populations. Unfortunately, the duration of treatment needed for long-term survival still remains unclear and further work is needed. Nevertheless the combination of regenerative medicine to CI technology presents a novel approach to developing CI technology.
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Fransson A, de Medina P, Paillasse MR, Silvente-Poirot S, Poirot M, Ulfendahl M. Dendrogenin A and B two new steroidal alkaloids increasing neural responsiveness in the deafened guinea pig. Front Aging Neurosci 2015; 7:145. [PMID: 26257649 PMCID: PMC4513558 DOI: 10.3389/fnagi.2015.00145] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/17/2015] [Accepted: 07/13/2015] [Indexed: 12/20/2022] Open
Abstract
Aim: To investigate the therapeutic potential for treating inner ear damage of two new steroidal alkaloid compounds, Dendrogenin A and Dendrogenin B, previously shown to be potent inductors of cell differentiation. Methods: Guinea pigs, unilaterally deafened by neomycin infusion, received a cochlear implant followed by immediate or a 2-week delayed treatment with Dendrogenin A, Dendrogenin B, and, as comparison artificial perilymph and glial cell-line derived neurotrophic factor. After a 4-week treatment period the animals were sacrificed and the cochleae processed for morphological analysis. Electrically-evoked auditory brainstem responses (eABRs) were measured weekly throughout the experiment. Results: Following immediate or delayed Dendrogenin treatment the electrical responsiveness was significantly maintained, in a similar extent as has been shown using neurotrophic factors. Histological analysis showed that the spiral ganglion neurons density was only slightly higher than the untreated group. Conclusions: Our results suggest that Dendrogenins constitute a new class of drugs with strong potential to improve cochlear implant efficacy and to treat neuropathy/synaptopathy related hearing loss. That electrical responsiveness was maintained despite a significantly reduced neural population suggests that the efficacy of cochlear implants is more related to the functional state of the spiral ganglion neurons than merely their number.
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Affiliation(s)
- Anette Fransson
- Department of Neuroscience, Karolinska Institutet Stockholm, Sweden
| | | | | | | | - Marc Poirot
- INSERM UMR 1037, Cancer Research Center of Toulouse Toulouse, France
| | - Mats Ulfendahl
- Department of Neuroscience, Karolinska Institutet Stockholm, Sweden
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Khalin I, Alyautdin R, Kocherga G, Bakar MA. Targeted delivery of brain-derived neurotrophic factor for the treatment of blindness and deafness. Int J Nanomedicine 2015; 10:3245-67. [PMID: 25995632 PMCID: PMC4425321 DOI: 10.2147/ijn.s77480] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Neurodegenerative causes of blindness and deafness possess a major challenge in their clinical management as proper treatment guidelines have not yet been found. Brain-derived neurotrophic factor (BDNF) has been established as a promising therapy against neurodegenerative disorders including hearing and visual loss. Unfortunately, the blood–retinal barrier and blood–cochlear barrier, which have a comparable structure to the blood–brain barrier prevent molecules of larger sizes (such as BDNF) from exiting the circulation and reaching the targeted cells. Anatomical features of the eye and ear allow use of local administration, bypassing histo-hematic barriers. This paper focuses on highlighting a variety of strategies proposed for the local administration of the BDNF, like direct delivery, viral gene therapy, and cell-based therapy, which have been shown to successfully improve development, survival, and function of spiral and retinal ganglion cells. The similarities and controversies for BDNF treatment of posterior eye diseases and inner ear diseases have been analyzed and compared. In this review, we also focus on the possibility of translation of this knowledge into clinical practice. And finally, we suggest that using nanoparticulate drug-delivery systems may substantially contribute to the development of clinically viable techniques for BDNF delivery into the cochlea or posterior eye segment, which, ultimately, can lead to a long-term or permanent rescue of auditory and optic neurons from degeneration.
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Affiliation(s)
- Igor Khalin
- Faculty of Medicine and Defence Health, National Defence University of Malaysia, Kuala Lumpur, Malaysia
| | - Renad Alyautdin
- Scientific Centre for Expertise of Medical Application Products, Moscow, Russia
| | - Ganna Kocherga
- Ophthalmic Microsurgery Department, International Medical Center Oftalmika, Kharkiv, Ukraine
| | - Muhamad Abu Bakar
- Faculty of Medicine and Defence Health, National Defence University of Malaysia, Kuala Lumpur, Malaysia
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George SS, Wise AK, Fallon JB, Shepherd RK. Evaluation of focused multipolar stimulation for cochlear implants in long-term deafened cats. J Neural Eng 2015; 12:036003. [PMID: 25834113 DOI: 10.1088/1741-2560/12/3/036003] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
OBJECTIVE Focused multipolar (FMP) stimulation has been shown to produce restricted neural activation using intracochlear stimulation in animals with a normal population of spiral ganglion neurons (SGNs). However, in a clinical setting, the widespread loss of SGNs and peripheral fibres following deafness is expected to influence the effectiveness of FMP. APPROACH We compared the efficacy of FMP stimulation to both monopolar (MP) and tripolar (TP) stimulation in long-term deafened cat cochleae (n = 8). Unlike our previous study, these cochleae contained <10% of the normal SGN population adjacent to the electrode array. We also evaluated the effect of electrode position on stimulation modes by using either modiolar facing or lateral wall facing half-band electrodes. The spread of neural activity across the inferior colliculus, a major nucleus within the central auditory pathway, was used as a measure of spatial selectivity. MAIN RESULTS In cochleae with significant SGN degeneration, we observed that FMP and TP stimulation resulted in greater spatial selectivity than MP stimulation (p < 0.001). However, thresholds were significantly higher for FMP and TP stimulation compared to MP stimulation (p < 0.001). No difference between FMP and TP stimulation was found in any measures. The high threshold levels for FMP stimulation was significantly reduced without compromising spatial selectivity by varying the degree of current focusing (referred as 'partial-FMP' stimulation). Spatial selectivity of all stimulation modes was unaffected by the electrode position. Finally, spatial selectivity in long-term deafened cochleae was significantly less than that of cochleae with normal SGN population (George S S et al 2014 J. Neural Eng. 11 065003). SIGNIFICANCE The present results indicate that the greater spatial selectivity of FMP and TP stimulation over MP stimulation is maintained in cochleae with significant neural degeneration and is not adversely affected by electrode position. The greater spatial selectivity of FMP and TP stimulation would be expected to result in improved clinical performance.
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Affiliation(s)
- Shefin S George
- The Bionics Institute, East Melbourne 3002, Australia. Department of Medical Bionics, University of Melbourne, Melbourne 3002, Australia
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Infrared neural stimulation fails to evoke neural activity in the deaf guinea pig cochlea. Hear Res 2015; 324:46-53. [PMID: 25796297 DOI: 10.1016/j.heares.2015.03.005] [Citation(s) in RCA: 50] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/29/2014] [Revised: 03/02/2015] [Accepted: 03/09/2015] [Indexed: 11/23/2022]
Abstract
At present there is some debate as to the processes by which infrared neural stimulation (INS) activates neurons in the cochlea, as the lasers used for INS can potentially generate a range of secondary stimuli e.g. an acoustic stimulus is produced when the light is absorbed by water. To clarify whether INS in the cochlea requires functioning hair cells and to explore the potential relevance to cochlear implants, experiments using INS were performed in the cochleae of both normal hearing and profoundly deaf guinea pigs. A response to laser stimulation was readily evoked in normal hearing cochlea. However, no response was evoked in any profoundly deaf cochleae, for either acute or chronic deafening, contrary to previous work where a response was observed after acute deafening with ototoxic drugs. A neural response to electrical stimulation was readily evoked in all cochleae after deafening. The absence of a response from optical stimuli in profoundly deaf cochleae suggests that the response from INS in the cochlea is hair cell mediated.
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Pinyon JL, Tadros SF, Froud KE, Y Wong AC, Tompson IT, Crawford EN, Ko M, Morris R, Klugmann M, Housley GD. Close-field electroporation gene delivery using the cochlear implant electrode array enhances the bionic ear. Sci Transl Med 2015; 6:233ra54. [PMID: 24760189 DOI: 10.1126/scitranslmed.3008177] [Citation(s) in RCA: 96] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The cochlear implant is the most successful bionic prosthesis and has transformed the lives of people with profound hearing loss. However, the performance of the "bionic ear" is still largely constrained by the neural interface itself. Current spread inherent to broad monopolar stimulation of the spiral ganglion neuron somata obviates the intrinsic tonotopic mapping of the cochlear nerve. We show in the guinea pig that neurotrophin gene therapy integrated into the cochlear implant improves its performance by stimulating spiral ganglion neurite regeneration. We used the cochlear implant electrode array for novel "close-field" electroporation to transduce mesenchymal cells lining the cochlear perilymphatic canals with a naked complementary DNA gene construct driving expression of brain-derived neurotrophic factor (BDNF) and a green fluorescent protein (GFP) reporter. The focusing of electric fields by particular cochlear implant electrode configurations led to surprisingly efficient gene delivery to adjacent mesenchymal cells. The resulting BDNF expression stimulated regeneration of spiral ganglion neurites, which had atrophied 2 weeks after ototoxic treatment, in a bilateral sensorineural deafness model. In this model, delivery of a control GFP-only vector failed to restore neuron structure, with atrophied neurons indistinguishable from unimplanted cochleae. With BDNF therapy, the regenerated spiral ganglion neurites extended close to the cochlear implant electrodes, with localized ectopic branching. This neural remodeling enabled bipolar stimulation via the cochlear implant array, with low stimulus thresholds and expanded dynamic range of the cochlear nerve, determined via electrically evoked auditory brainstem responses. This development may broadly improve neural interfaces and extend molecular medicine applications.
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Affiliation(s)
- Jeremy L Pinyon
- Translational Neuroscience Facility and Department of Physiology, School of Medical Sciences, University of New South Wales, UNSW Australia, Sydney, New South Wales 2052, Australia
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Postnatal expression of neurotrophic factors accessible to spiral ganglion neurons in the auditory system of adult hearing and deafened rats. J Neurosci 2014; 34:13110-26. [PMID: 25253857 DOI: 10.1523/jneurosci.1014-14.2014] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Spiral ganglion neurons (SGNs) receive input from cochlear hair cells and project from the cochlea to the cochlear nucleus. After destruction of hair cells with aminoglycoside antibiotics or noise, SGNs gradually die. It has been assumed that SGN death is attributable to loss of neurotrophic factors (NTFs) derived from hair cells or supporting cells in the organ of Corti (OC). We used quantitative PCR (qPCR) to assay NTF expression-neurotrophin-3 (NT-3), BDNF, GDNF, neurturin, artemin, and CNTF-in the OC and cochlear nucleus at various ages from postnatal day 0 (P0) to P90 in control hearing and neonatally deafened rats. NT-3, neurturin, and CNTF were most abundant in the postnatal hearing OC; CNTF and neurturin most abundant in the cochlear nucleus. In the OC, NT-3 and CNTF showed a postnatal increase in expression approximately concomitant with hearing onset. In rats deafened by daily kanamycin injections (from P8 to P16), surviving inner hair cells were evident at P16 but absent by P19, with most postsynaptic boutons lost before P16. NT-3 and CNTF, which normally increase postnatally, had significantly reduced expression in the OC of deafened rats, although CNTF was expressed throughout the time that SGNs were dying. In contrast, neurturin expression was constant, unaffected by deafening or by age. CNTF and neurturin expression in the cochlear nucleus was unaffected by deafening or age. Thus, NTFs other than NT-3 are available to SGNs even as they are dying after deafening, apparently conflicting with the hypothesis that SGN death is attributable to lack of NTFs.
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Schendzielorz P, Schmitz T, Moseke C, Gbureck U, FrFlich K, Rak K, Groll JR, Hagen R, Radeloff A. Plasma-Assisted Hydrophilization of Cochlear Implant Electrode Array Surfaces Enables Adhesion of Neurotrophin-Secreting Cells. ORL J Otorhinolaryngol Relat Spec 2014; 76:257-65. [DOI: 10.1159/000368321] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2014] [Accepted: 09/09/2014] [Indexed: 11/19/2022]
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Wang Y, Wise AK, Tan J, Maina JW, Shepherd RK, Caruso F. Mesoporous silica supraparticles for sustained inner-ear drug delivery. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2014; 10:4244-4248. [PMID: 25099026 DOI: 10.1002/smll.201401767] [Citation(s) in RCA: 20] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/17/2014] [Indexed: 06/03/2023]
Abstract
Mesoporous silica supraparticles (MS-SPs) are prepared via self-assembly of mesoporous silica nanoparticles under capillary force action in confined droplets. The MS-SPs are effective carriers for sustained drug delivery. Animal studies show that these particles are suitable for chronic intracochlear implantation, and neurotrophins released from the MS-SPs can efficiently rescue primary auditory neurons in an in vivo sensorineural hearing loss model.
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Affiliation(s)
- Yajun Wang
- Department of Chemical and Biomolecular Engineering, The University of Melbourne, Parkville, Victoria, 3010, Australia; Department of Chemistry, Fudan University, Shanghai, 200433, P. R. China
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