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Zhang B, Hu Y, Du H, Han S, Ren L, Cheng H, Wang Y, Gao X, Zheng S, Cui Q, Tian L, Liu T, Sun J, Chai R. Tissue engineering strategies for spiral ganglion neuron protection and regeneration. J Nanobiotechnology 2024; 22:458. [PMID: 39085923 PMCID: PMC11293049 DOI: 10.1186/s12951-024-02742-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/08/2024] [Accepted: 07/25/2024] [Indexed: 08/02/2024] Open
Abstract
Cochlear implants can directly activate the auditory system's primary sensory neurons, the spiral ganglion neurons (SGNs), via circumvention of defective cochlear hair cells. This bypass restores auditory input to the brainstem. SGN loss etiologies are complex, with limited mammalian regeneration. Protecting and revitalizing SGN is critical. Tissue engineering offers a novel therapeutic strategy, utilizing seed cells, biomolecules, and scaffold materials to create a cellular environment and regulate molecular cues. This review encapsulates the spectrum of both human and animal research, collating the factors contributing to SGN loss, the latest advancements in the utilization of exogenous stem cells for auditory nerve repair and preservation, the taxonomy and mechanism of action of standard biomolecules, and the architectural components of scaffold materials tailored for the inner ear. Furthermore, we delineate the potential and benefits of the biohybrid neural interface, an incipient technology in the realm of implantable devices. Nonetheless, tissue engineering requires refined cell selection and differentiation protocols for consistent SGN quality. In addition, strategies to improve stem cell survival, scaffold biocompatibility, and molecular cue timing are essential for biohybrid neural interface integration.
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Affiliation(s)
- Bin Zhang
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Public Health, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China
- Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China
| | - Yangnan Hu
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Public Health, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China.
- Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China.
| | - Haoliang Du
- Department of Otolaryngology Head and Neck Surgery, Nanjing Drum Tower Hospital, Affiliated Hospital of Medical School, Jiangsu Provincial Key Medical Discipline (Laboratory), Nanjing University, Nanjing, 210008, China
| | - Shanying Han
- Department of Otolaryngology Head and Neck Surgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China
| | - Lei Ren
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Public Health, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China
| | - Hong Cheng
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Public Health, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China
| | - Yusong Wang
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Public Health, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China
| | - Xin Gao
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Public Health, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China
| | - Shasha Zheng
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Public Health, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China
| | - Qingyue Cui
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Public Health, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China
| | - Lei Tian
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Public Health, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China.
| | - Tingting Liu
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Public Health, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China.
| | - Jiaqiang Sun
- Department of Otolaryngology-Head and Neck Surgery, Division of Life Sciences and Medicine, The First Affiliated Hospital of USTC, University of Science and Technology of China, Hefei, Anhui, 230001, China.
| | - Renjie Chai
- State Key Laboratory of Digital Medical Engineering, Department of Otolaryngology Head and Neck Surgery, Zhongda Hospital, School of Public Health, Advanced Institute for Life and Health, Jiangsu Province High-Tech Key Laboratory for Bio-Medical Research, Southeast University, Nanjing, 210096, China.
- Co-Innovation Center of Neuroregeneration, Nantong University, Nantong, 226001, China.
- Department of Otolaryngology Head and Neck Surgery, Sichuan Provincial People's Hospital, University of Electronic Science and Technology of China, Chengdu, 610072, China.
- Department of Neurology, Aerospace Center Hospital, School of Life Science, Beijing Institute of Technology, Beijing, 100081, China.
- Institute for Stem Cell and Regeneration, Chinese Academy of Science, Beijing, China.
- Southeast University Shenzhen Research Institute, Shenzhen, 518063, China.
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Vecchi JT, Claussen AD, Hansen MR. Decreasing the physical gap in the neural-electrode interface and related concepts to improve cochlear implant performance. Front Neurosci 2024; 18:1425226. [PMID: 39114486 PMCID: PMC11303154 DOI: 10.3389/fnins.2024.1425226] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2024] [Accepted: 07/11/2024] [Indexed: 08/10/2024] Open
Abstract
Cochlear implants (CI) represent incredible devices that restore hearing perception for those with moderate to profound sensorineural hearing loss. However, the ability of a CI to restore complex auditory function is limited by the number of perceptually independent spectral channels provided. A major contributor to this limitation is the physical gap between the CI electrodes and the target spiral ganglion neurons (SGNs). In order for CI electrodes to stimulate SGNs more precisely, and thus better approximate natural hearing, new methodologies need to be developed to decrease this gap, (i.e., transitioning CIs from a far-field to near-field device). In this review, strategies aimed at improving the neural-electrode interface are discussed in terms of the magnitude of impact they could have and the work needed to implement them. Ongoing research suggests current clinical efforts to limit the CI-related immune response holds great potential for improving device performance. This could eradicate the dense, fibrous capsule surrounding the electrode and enhance preservation of natural cochlear architecture, including SGNs. In the long term, however, optimized future devices will likely need to induce and guide the outgrowth of the peripheral process of SGNs to be in closer proximity to the CI electrode in order to better approximate natural hearing. This research is in its infancy; it remains to be seen which strategies (surface patterning, small molecule release, hydrogel coating, etc.) will be enable this approach. Additionally, these efforts aimed at optimizing CI function will likely translate to other neural prostheses, which face similar issues.
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Affiliation(s)
- Joseph T. Vecchi
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, Iowa City, IA, United States
- Department of Otolaryngology Head-Neck Surgery, Carver College of Medicine, Iowa City, IA, United States
| | - Alexander D. Claussen
- Department of Otolaryngology Head-Neck Surgery, Carver College of Medicine, Iowa City, IA, United States
| | - Marlan R. Hansen
- Department of Molecular Physiology and Biophysics, Carver College of Medicine, Iowa City, IA, United States
- Department of Otolaryngology Head-Neck Surgery, Carver College of Medicine, Iowa City, IA, United States
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Changes in the Electrically Evoked Compound Action Potential over time After Implantation and Subsequent Deafening in Guinea Pigs. J Assoc Res Otolaryngol 2022; 23:721-738. [PMID: 35948695 PMCID: PMC9789241 DOI: 10.1007/s10162-022-00864-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 07/12/2022] [Indexed: 01/06/2023] Open
Abstract
The electrically evoked compound action potential (eCAP) is a direct measure of the responsiveness of the auditory nerve to electrical stimulation from a cochlear implant (CI). CIs offer a unique opportunity to study the auditory nerve's electrophysiological behavior in individual human subjects over time. In order to understand exactly how the eCAP relates to the condition of the auditory nerve, it is crucial to compare changes in the eCAP over time in a controlled model of deafness-induced auditory nerve degeneration. In the present study, 10 normal-hearing young adult guinea pigs were implanted and deafened 4 weeks later, so that the effect of deafening could be monitored within-subject over time. Following implantation, but before deafening, most examined eCAP characteristics significantly changed, suggesting increasing excitation efficacy (e.g., higher maximum amplitude, lower threshold, shorter latency). Conversely, inter-phase gap (IPG) effects on these measures - within-subject difference measures that have been shown to correlate well with auditory nerve survival - did not vary for most eCAP characteristics. After deafening, we observed an initial increase in excitability (steeper slope of the eCAP amplitude growth function (AGF), lower threshold, shorter latency and peak width) which typically returned to normal-hearing levels within a week, after which a slower process, probably reflecting spiral ganglion cell loss, took place over the remaining 6 weeks (e.g., decrease in maximum amplitude, AGF slope, peak area, and IPG effect for AGF slope; increase in IPG effect for latency). Our results suggest that gradual changes in peak width and latency reflect the rate of neural degeneration, while peak area, maximum amplitude, and AGF slope reflect neural population size, which may be valuable for clinical diagnostics.
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Effects of an enhanced acoustic environment on residual hearing following chronic cochlear implantation and electrical stimulation in the partially deafened cat. Hear Res 2022; 426:108635. [DOI: 10.1016/j.heares.2022.108635] [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: 11/03/2021] [Revised: 08/10/2022] [Accepted: 10/11/2022] [Indexed: 11/04/2022]
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Eggink MC, Frijns JHM, Sagers JE, O'Malley JT, Liberman MC, Stankovic KM. Human vestibular schwannoma reduces density of auditory nerve fibers in the osseous spiral lamina. Hear Res 2022; 418:108458. [PMID: 35334332 PMCID: PMC11181009 DOI: 10.1016/j.heares.2022.108458] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/22/2021] [Accepted: 02/05/2022] [Indexed: 12/24/2022]
Abstract
Hearing loss in patients with vestibular schwannoma (VS) is commonly attributed to mechanical compression of the auditory nerve, though recent studies suggest that this retrocochlear pathology may be augmented by cochlear damage. Although VS-associated loss of inner hair cells, outer hair cells, and spiral ganglion cells has been reported, it is unclear to what extent auditory-nerve peripheral axons are damaged in VS patients. Understanding the degree of damage VSs cause to auditory nerve fibers (ANFs) is important for accurately modeling clinical outcomes of cochlear implantation, which is a therapeutic option to rehabilitate hearing in VS-affected ears. A retrospective analysis of human temporal-bone histopathology was performed on archival specimens from the Massachusetts Eye and Ear collection. Seven patients met our inclusion criteria based on the presence of sporadic, unilateral, untreated VS. Tangential sections of five cochlear regions were stained with hematoxylin and eosin, and adjacent sections were stained to visualize myelinated ANFs and efferent fibers. Following confocal microscopy, peripheral axons of ANFs within the osseous spiral lamina were quantified manually, where feasible, and with a "pixel counting" method, applicable to all sections. ANF density was substantially reduced on the VS side compared to the unaffected contralateral side. In the upper basal turn, a significant difference between the VS side and unaffected contralateral side was found using both counting methods, corresponding to the region tuned to 2000 Hz. Even spiral ganglion cells (SGCs) contralateral to VS were affected by the tumor as the majority of contralateral SGC counts were below average for age. This observation provides histological insight into the clinical observation that unilateral vestibular schwannomas pose a long-term risk of progression of hearing loss in the contralateral ear as well. Our pixel counting method for ANF quantification in the osseous spiral lamina is applicable to other pathologies involving sensorineural hearing loss. Future research is needed to classify ANFs into morphological categories, accurately predict their electrical properties, and use this knowledge to inform optimal cochlear implant programming strategies.
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Affiliation(s)
- Maura C Eggink
- Department of Otolaryngology - Head and Neck Surgery, Harvard Medical School, Boston, MA, USA; Eaton Peabody Laboratories and Department of Otolaryngology - Head and Neck Surgery, Massachusetts Eye and Ear, Boston, MA, USA; Department of Otorhinolaryngology, Leiden University Medical Center, Leiden, the Netherlands; Department of Otorhinolaryngology, Amsterdam UMC, location Academic Medical Center, University of Amsterdam, the Netherlands
| | - Johan H M Frijns
- Department of Otorhinolaryngology, Leiden University Medical Center, Leiden, the Netherlands; The Leiden Institute for Brain and Cognition, Leiden, the Netherlands
| | - Jessica E Sagers
- Eaton Peabody Laboratories and Department of Otolaryngology - Head and Neck Surgery, Massachusetts Eye and Ear, Boston, MA, USA
| | - Jennifer T O'Malley
- Eaton Peabody Laboratories and Department of Otolaryngology - Head and Neck Surgery, Massachusetts Eye and Ear, Boston, MA, USA
| | - M Charles Liberman
- Department of Otolaryngology - Head and Neck Surgery, Harvard Medical School, Boston, MA, USA; Eaton Peabody Laboratories and Department of Otolaryngology - Head and Neck Surgery, Massachusetts Eye and Ear, Boston, MA, USA
| | - Konstantina M Stankovic
- Department of Otolaryngology - Head and Neck Surgery, Harvard Medical School, Boston, MA, USA; Eaton Peabody Laboratories and Department of Otolaryngology - Head and Neck Surgery, Massachusetts Eye and Ear, Boston, MA, USA; Department of Otolaryngology, Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA, USA.
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Tringides CM, Mooney DJ. Materials for Implantable Surface Electrode Arrays: Current Status and Future Directions. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2022; 34:e2107207. [PMID: 34716730 DOI: 10.1002/adma.202107207] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/10/2021] [Revised: 10/26/2021] [Indexed: 06/13/2023]
Abstract
Surface electrode arrays are mainly fabricated from rigid or elastic materials, and precisely manipulated ductile metal films, which offer limited stretchability. However, the living tissues to which they are applied are nonlinear viscoelastic materials, which can undergo significant mechanical deformation in dynamic biological environments. Further, the same arrays and compositions are often repurposed for vastly different tissues rather than optimizing the materials and mechanical properties of the implant for the target application. By first characterizing the desired biological environment, and then designing a technology for a particular organ, surface electrode arrays may be more conformable, and offer better interfaces to tissues while causing less damage. Here, the various materials used in each component of a surface electrode array are first reviewed, and then electrically active implants in three specific biological systems, the nervous system, the muscular system, and skin, are described. Finally, the fabrication of next-generation surface arrays that overcome current limitations is discussed.
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Affiliation(s)
- Christina M Tringides
- Harvard Program in Biophysics, Harvard University, Cambridge, MA, 02138, USA
- Harvard-MIT Division in Health Sciences and Technology, Massachusetts Institute of Technology, Cambridge, MA, 02139, USA
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA, 02138, USA
| | - David J Mooney
- Wyss Institute for Biologically Inspired Engineering, Harvard University, Cambridge, MA, 02138, USA
- John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA, 02138, USA
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Radeloff A, Nada N, El Mahallawi T, Kolkaila E, Vollmer M, Rak K, Hagen R, Schendzielorz P. Transplantation of adipose-derived stromal cells protects functional and morphological auditory nerve integrity in a model of cochlear implantation. Neuroreport 2021; 32:776-782. [PMID: 33994529 DOI: 10.1097/wnr.0000000000001651] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
Cochlear implants are considered the gold standard therapy for subjects with severe hearing loss and deafness. Cochlear implants bypass the damaged hair cells and directly stimulate spiral ganglion neurons (SGNs) of the auditory nerve. Hence, the presence of functional SGNs is crucial for speech perception in electric hearing with a cochlear implant. In deaf individuals, SGNs progressively degenerate due to the lack of neurotrophic support, normally provided by sensory cells of the inner ear. Adipose-derived stromal cells (ASCs) are known to produce neurotrophic factors. In a guinea pig model of sensory hearing loss and cochlear implantation, ASCs were autologously transplanted into the scala tympani prior to insertion of a cochlear implant on one side. Electrically evoked auditory brain stem responses (eABR) were recorded 8 weeks after cochlear implantation. At conclusion of the experiment, the cochleae were histologically evaluated. Compared to untreated control animals, transplantation of ASCs resulted in an increased number of SGNs and their peripheral neurites. In ASC-transplanted animals, mean eABR thresholds were lower and suprathreshold amplitudes larger, suggesting a larger population of intact auditory nerve fibers. Moreover, when compared to controls, amplitude-level functions of eABRs in ASC transplanted animals demonstrated steeper slopes in response to increasing interphase gaps (IPGs), indicative of better functionality of the auditory nerve. In summary, results suggest that transplantation of autologous ASCs into the deaf inner ear may have protective effects on the survival of SGNs and their peripheral processes and may thus contribute to long-term benefits in speech discrimination performance in cochlear implant subjects.
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Affiliation(s)
- Andreas Radeloff
- Division of Oto-Rhino-Laryngology, Head and Neck Surgery, Carl von Ossietzky-University
- Cluster of excellence "Hearing 4 All"
- Research Center Neurosensory Science, Oldenburg, Germany
| | - Nashwa Nada
- Department of Oto-Rhino-Laryngology, Head and Neck Surgery, Tanta University Hospitals, Tanta, Egypt
| | - Trandil El Mahallawi
- Department of Oto-Rhino-Laryngology, Head and Neck Surgery, Tanta University Hospitals, Tanta, Egypt
| | - Enaas Kolkaila
- Department of Oto-Rhino-Laryngology, Head and Neck Surgery, Tanta University Hospitals, Tanta, Egypt
| | - Maike Vollmer
- Department of Otol-Rhino-Laryngology, Head and Neck Surgery, University Magdeburg and Leibniz Institute for Neurobiology, Magdeburg
| | - Kristen Rak
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery, University of Würzburg, Germany
| | - Rudolf Hagen
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery, University of Würzburg, Germany
| | - Philipp Schendzielorz
- Department of Oto-Rhino-Laryngology, Plastic, Aesthetic and Reconstructive Head and Neck Surgery, University of Würzburg, Germany
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Sunwoo SH, Ha KH, Lee S, Lu N, Kim DH. Wearable and Implantable Soft Bioelectronics: Device Designs and Material Strategies. Annu Rev Chem Biomol Eng 2021; 12:359-391. [PMID: 34097846 DOI: 10.1146/annurev-chembioeng-101420-024336] [Citation(s) in RCA: 49] [Impact Index Per Article: 16.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
High-performance wearable and implantable devices capable of recording physiological signals and delivering appropriate therapeutics in real time are playing a pivotal role in revolutionizing personalized healthcare. However, the mechanical and biochemical mismatches between rigid, inorganic devices and soft, organic human tissues cause significant trouble, including skin irritation, tissue damage, compromised signal-to-noise ratios, and limited service time. As a result, profuse research efforts have been devoted to overcoming these issues by using flexible and stretchable device designs and soft materials. Here, we summarize recent representative research and technological advances for soft bioelectronics, including conformable and stretchable device designs, various types of soft electronic materials, and surface coating and treatment methods. We also highlight applications of these strategies to emerging soft wearable and implantable devices. We conclude with some current limitations and offer future prospects of this booming field.
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Affiliation(s)
- Sung-Hyuk Sunwoo
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea; .,School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul 08826, Republic of Korea
| | - Kyoung-Ho Ha
- Department of Mechanical Engineering, The University of Texas at Austin, Texas 78712, USA;
| | - Sangkyu Lee
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea;
| | - Nanshu Lu
- Department of Mechanical Engineering, The University of Texas at Austin, Texas 78712, USA; .,Center for Mechanics of Solids, Structures and Materials, Department of Aerospace Engineering and Engineering Mechanics, Department of Biomedical Engineering, and Texas Material Institute, The University of Texas at Austin, Texas 78712, USA
| | - Dae-Hyeong Kim
- Center for Nanoparticle Research, Institute for Basic Science (IBS), Seoul 08826, Republic of Korea; .,School of Chemical and Biological Engineering, Institute of Chemical Processes, Seoul National University, Seoul 08826, Republic of Korea.,Department of Materials Science and Engineering, Seoul National University, Seoul 08826, Republic of Korea
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Schulze J, Staecker H, Wedekind D, Lenarz T, Warnecke A. Expression pattern of brain-derived neurotrophic factor and its associated receptors: Implications for exogenous neurotrophin application. Hear Res 2020; 413:108098. [PMID: 33143996 DOI: 10.1016/j.heares.2020.108098] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/16/2020] [Revised: 08/24/2020] [Accepted: 10/19/2020] [Indexed: 01/20/2023]
Abstract
The application of neurotrophins such as brain-derived neurotrophic factor (BDNF) is a promising pharmacological approach in cochlear implant research. Several in vitro and in vivo studies demonstrated that treatment with neurotrophins support the spiral ganglion neuron (SGN) survival and the synapses. Of the more than 40 companies that are working in the field of inner ear therapeutics, only one company is currently advancing BDNF towards clinical translation. Thus, there are no approved clinical therapies with neurotrophins, their precursors or neurotrophin-like substances. For a better understanding of the mechanisms of BDNF in the inner ear, we analysed the expression of mature BDNF (mBDNF), its pro-form proBDNF and their respective receptors the low affinity p75 neurotrophin receptor (p75NTR) and the neurotrophic receptor tyrosine kinase 2 (NTRK2). In the adult murine inner ear, mBDNF is expressed in the inner and outer hair cells (IHC and OHC) of the organ of Corti and in the spiral ganglion of the Rosenthal's canal, whereas proBDNF is only detected in the supporting cells below the OHC. The corresponding receptors NTRK2 and p75NTR are expressed in the spiral ganglion whereof p75NTR is stronger expressed. For more insights in the effects of mBDNF and proBDNF on inner ear specific cells, we treated primary dissociated SGN with different concentrations of mBDNF and proBDNF alone and in combination. Interestingly, treatment with proBDNF is not toxic for SGN but simultaneously not protective. However, combined treatment of mBDNF and proBDNF maintained and perhaps slightly increased the protective effect of mBDNF. Thus, the mixture of mBDNF and proBDNF could be the new direction for the development of BDNF-based therapeutics in cochlear implantation and could represent more precisely the natural environment.
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Affiliation(s)
- Jennifer Schulze
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Hannover, Germany; Cluster of Excellence "Hearing4all" of the German Research Foundation (EXC 2177/1).
| | - Hinrich Staecker
- Department of Otolaryngology Head and Neck Surgery, University of Kansas School of Medicine, Kansas City, Kansas, USA
| | - Dirk Wedekind
- Department of experimental animal science, Hannover Medical School, Hannover, Germany
| | - Thomas Lenarz
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Hannover, Germany; Cluster of Excellence "Hearing4all" of the German Research Foundation (EXC 2177/1)
| | - Athanasia Warnecke
- Department of Otorhinolaryngology, Head and Neck Surgery, Hannover Medical School, Hannover, Germany; Cluster of Excellence "Hearing4all" of the German Research Foundation (EXC 2177/1)
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Yang JW, Yu ZY, Cheng SJ, Chung JHY, Liu X, Wu CY, Lin SF, Chen GY. Graphene Oxide-Based Nanomaterials: An Insight into Retinal Prosthesis. Int J Mol Sci 2020; 21:E2957. [PMID: 32331417 PMCID: PMC7216005 DOI: 10.3390/ijms21082957] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2020] [Revised: 04/17/2020] [Accepted: 04/20/2020] [Indexed: 12/27/2022] Open
Abstract
Retinal prosthesis has recently emerged as a treatment strategy for retinopathies, providing excellent assistance in the treatment of age-related macular degeneration (AMD) and retinitis pigmentosa. The potential application of graphene oxide (GO), a highly biocompatible nanomaterial with superior physicochemical properties, in the fabrication of electrodes for retinal prosthesis, is reviewed in this article. This review integrates insights from biological medicine and nanotechnology, with electronic and electrical engineering technological breakthroughs, and aims to highlight innovative objectives in developing biomedical applications of retinal prosthesis.
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Affiliation(s)
- Jia-Wei Yang
- Department of Electrical and Computer Engineering, College of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu 300, Taiwan; (J.-W.Y.); (S.-J.C.); (S.-F.L.)
- Institute of Biomedical Engineering, College of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu 300, Taiwan;
| | - Zih-Yu Yu
- Institute of Biomedical Engineering, College of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu 300, Taiwan;
| | - Sheng-Jen Cheng
- Department of Electrical and Computer Engineering, College of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu 300, Taiwan; (J.-W.Y.); (S.-J.C.); (S.-F.L.)
- Institute of Biomedical Engineering, College of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu 300, Taiwan;
| | - Johnson H. Y. Chung
- ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Wollongong, NSW 2500, Australia; (J.H.Y.C.); (X.L.)
| | - Xiao Liu
- ARC Centre of Excellence for Electromaterials Science, Intelligent Polymer Research Institute, University of Wollongong, Wollongong, NSW 2500, Australia; (J.H.Y.C.); (X.L.)
| | - Chung-Yu Wu
- Department of Electrical Engineering, National Chiao Tung University, Hsinchu, 300, Taiwan;
| | - Shien-Fong Lin
- Department of Electrical and Computer Engineering, College of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu 300, Taiwan; (J.-W.Y.); (S.-J.C.); (S.-F.L.)
- Institute of Biomedical Engineering, College of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu 300, Taiwan;
| | - Guan-Yu Chen
- Department of Electrical and Computer Engineering, College of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu 300, Taiwan; (J.-W.Y.); (S.-J.C.); (S.-F.L.)
- Institute of Biomedical Engineering, College of Electrical and Computer Engineering, National Chiao Tung University, Hsinchu 300, Taiwan;
- Department of Biological Science and Technology, National Chiao Tung University, Hsinchu 300, Taiwan
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Schwieger J, Hamm A, Gepp MM, Schulz A, Hoffmann A, Lenarz T, Scheper V. Alginate-encapsulated brain-derived neurotrophic factor-overexpressing mesenchymal stem cells are a promising drug delivery system for protection of auditory neurons. J Tissue Eng 2020; 11:2041731420911313. [PMID: 32341778 PMCID: PMC7168777 DOI: 10.1177/2041731420911313] [Citation(s) in RCA: 21] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 02/08/2020] [Indexed: 12/23/2022] Open
Abstract
The cochlear implant outcome is possibly improved by brain-derived neurotrophic factor treatment protecting spiral ganglion neurons. Implantation of genetically modified mesenchymal stem cells may enable the required long-term brain-derived neurotrophic factor administration. Encapsulation of mesenchymal stem cells in ultra-high viscous alginate may protect the mesenchymal stem cells from the recipient’s immune system and prevent their uncontrolled migration. Alginate stability and survival of mesenchymal stem cells in alginate were evaluated. Brain-derived neurotrophic factor production was measured and its protective effect was analyzed in dissociated rat spiral ganglion neuron co-culture. Since the cochlear implant is an active electrode, alginate–mesenchymal stem cell samples were electrically stimulated and alginate stability and mesenchymal stem cell survival were investigated. Stability of ultra-high viscous-alginate and alginate–mesenchymal stem cells was proven. Brain-derived neurotrophic factor production was detectable and spiral ganglion neuron survival, bipolar morphology, and neurite outgrowth were increased. Moderate electrical stimulation did not affect the mesenchymal stem cell survival and their viability was good within the investigated time frame. Local drug delivery by ultra-high viscous-alginate-encapsulated brain-derived neurotrophic factor–overexpressing mesenchymal stem cells is a promising strategy to improve the cochlear implant outcome.
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Affiliation(s)
- Jana Schwieger
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany.,NIFE-Lower Saxony Centre for Biomedical Engineering, Implant Research and Development, Hannover, Germany
| | - Anika Hamm
- NIFE-Lower Saxony Centre for Biomedical Engineering, Implant Research and Development, Hannover, Germany.,Department of Orthopaedic Surgery, Hannover Medical School, Hannover, Germany
| | - Michael M Gepp
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany.,Fraunhofer Project Center for Stem Cell Process Engineering, Würzburg, Germany
| | - André Schulz
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany
| | - Andrea Hoffmann
- NIFE-Lower Saxony Centre for Biomedical Engineering, Implant Research and Development, Hannover, Germany.,Department of Orthopaedic Surgery, Hannover Medical School, Hannover, Germany
| | - Thomas Lenarz
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany.,NIFE-Lower Saxony Centre for Biomedical Engineering, Implant Research and Development, Hannover, Germany.,Cluster of Excellence Hearing4all, German Research Foundation, Hannover, Germany
| | - Verena Scheper
- Department of Otolaryngology, Hannover Medical School, Hannover, Germany.,NIFE-Lower Saxony Centre for Biomedical Engineering, Implant Research and Development, Hannover, Germany.,Cluster of Excellence Hearing4all, German Research Foundation, Hannover, Germany
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12
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Dalrymple AN, Robles UA, Huynh M, Nayagam BA, Green RA, Poole-Warren LA, Fallon JB, Shepherd RK. Electrochemical and biological performance of chronically stimulated conductive hydrogel electrodes. J Neural Eng 2020; 17:026018. [DOI: 10.1088/1741-2552/ab7cfc] [Citation(s) in RCA: 24] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
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13
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Rochford AE, Carnicer-Lombarte A, Curto VF, Malliaras GG, Barone DG. When Bio Meets Technology: Biohybrid Neural Interfaces. ADVANCED MATERIALS (DEERFIELD BEACH, FLA.) 2020; 32:e1903182. [PMID: 31517403 DOI: 10.1002/adma.201903182] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/18/2019] [Revised: 07/06/2019] [Indexed: 06/10/2023]
Abstract
The development of electronics capable of interfacing with the nervous system is a rapidly advancing field with applications in basic science and clinical translation. Devices containing arrays of electrodes can be used in the study of cells grown in culture or can be implanted into damaged or dysfunctional tissue to restore normal function. While devices are typically designed and used exclusively for one of these two purposes, there have been increasing efforts in developing implantable electrode arrays capable of housing cultured cells, referred to as biohybrid implants. Once implanted, the cells within these implants integrate into the tissue, serving as a mediator of the electrode-tissue interface. This biological component offers unique advantages to these implant designs, providing better tissue integration and potentially long-term stability. Herein, an overview of current research into biohybrid devices, as well as the historical background that led to their development are provided, based on the host anatomical location for which they are designed (CNS, PNS, or special senses). Finally, a summary of the key challenges of this technology and potential future research directions are presented.
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Affiliation(s)
- Amy E Rochford
- Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge, CB3 0FA, UK
| | | | - Vincenzo F Curto
- Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge, CB3 0FA, UK
| | - George G Malliaras
- Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge, CB3 0FA, UK
| | - Damiano G Barone
- Electrical Engineering Division, Department of Engineering, University of Cambridge, Cambridge, CB3 0FA, UK
- Department of Clinical Neurosciences, University of Cambridge, Cambridge, CB2 0QQ, UK
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14
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Santos-Vizcaino E, Orive G, Pedraz JL, Hernandez RM. Clinical Applications of Cell Encapsulation Technology. Methods Mol Biol 2020; 2100:473-491. [PMID: 31939144 DOI: 10.1007/978-1-0716-0215-7_32] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Cell encapsulation comprises immunoisolation three-dimensional systems for housing therapeutic cells that secrete bioactive compounds de novo and in a sustained manner. This allows transplantation of multiple allo- or xenogeneic cells without the aid of immunosuppressant drugs. Recent advances in the field have provided improvements to these cell-based drug delivery systems, which have gained the attention of the scientific community and inspired many biotechnological companies to develop their own product candidates. From micro- to macroencapsulation devices, this chapter describes some of the most important approaches that are being currently tested in late-stage clinical trials and are likely to reach the market as future game changers. Most studies involve the treatment of diabetes, eye disorders, and diseases of the central nervous system. However, many other pathologies are also amenable to benefit from this technology. Latest advances to overcome major pending challenges related to biosafety and efficacy are also discussed.
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Affiliation(s)
- Edorta Santos-Vizcaino
- NanoBioCel Group, Laboratory of Pharmaceutics, School of Pharmacy, University of the Basque Country (UPV/EHU), Vitoria-Gasteiz, Spain.,Biomedical Research Networking Centre in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Vitoria-Gasteiz, Spain
| | - Gorka Orive
- NanoBioCel Group, Laboratory of Pharmaceutics, School of Pharmacy, University of the Basque Country (UPV/EHU), Vitoria-Gasteiz, Spain.,Biomedical Research Networking Centre in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Vitoria-Gasteiz, Spain.,University Institute for Regenerative Medicine and Oral Implantology-UIRMI (UPV/EHU-Fundación Eduardo Anitua), Vitoria, Spain.,BTI Biotechnology Institute, Vitoria, Spain
| | - Jose Luis Pedraz
- NanoBioCel Group, Laboratory of Pharmaceutics, School of Pharmacy, University of the Basque Country (UPV/EHU), Vitoria-Gasteiz, Spain.,Biomedical Research Networking Centre in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Vitoria-Gasteiz, Spain
| | - Rosa Maria Hernandez
- NanoBioCel Group, Laboratory of Pharmaceutics, School of Pharmacy, University of the Basque Country (UPV/EHU), Vitoria-Gasteiz, Spain. .,Biomedical Research Networking Centre in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Vitoria-Gasteiz, Spain.
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15
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Hügl S, Scheper V, Gepp MM, Lenarz T, Rau TS, Schwieger J. Coating stability and insertion forces of an alginate-cell-based drug delivery implant system for the inner ear. J Mech Behav Biomed Mater 2019; 97:90-98. [DOI: 10.1016/j.jmbbm.2019.05.007] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/10/2018] [Revised: 04/01/2019] [Accepted: 05/03/2019] [Indexed: 12/20/2022]
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16
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Pinyon JL, von Jonquieres G, Crawford EN, Duxbury M, Al Abed A, Lovell NH, Klugmann M, Wise AK, Fallon JB, Shepherd RK, Birman CS, Lai W, McAlpine D, McMahon C, Carter PM, Enke YL, Patrick JF, Schilder AG, Marie C, Scherman D, Housley GD. Neurotrophin gene augmentation by electrotransfer to improve cochlear implant hearing outcomes. Hear Res 2019; 380:137-149. [DOI: 10.1016/j.heares.2019.06.002] [Citation(s) in RCA: 13] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/06/2019] [Revised: 06/07/2019] [Accepted: 06/12/2019] [Indexed: 12/14/2022]
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17
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Ma Y, Cortez-Jugo C, Li J, Lin Z, Richardson RT, Han Y, Zhou J, Björnmalm M, Feeney OM, Zhong QZ, Porter CJH, Wise AK, Caruso F. Engineering Biocoatings To Prolong Drug Release from Supraparticles. Biomacromolecules 2019; 20:3425-3434. [DOI: 10.1021/acs.biomac.9b00710] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Affiliation(s)
- Yutian Ma
- Bionics Institute, East Melbourne, Victoria 3002, Australia
| | | | | | | | | | | | | | - Mattias Björnmalm
- Bionics Institute, East Melbourne, Victoria 3002, Australia
- Department of Materials, Department of Bioengineering, and the Institute of Biomedical Engineering, Imperial College London, London SW7 2AZ, U.K
| | - Orlagh M. Feeney
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, and Drug Delivery Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | | | - Christopher J. H. Porter
- ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, and Drug Delivery Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, Victoria 3052, Australia
| | - Andrew K. Wise
- Bionics Institute, East Melbourne, Victoria 3002, Australia
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18
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AAV-Mediated Neurotrophin Gene Therapy Promotes Improved Survival of Cochlear Spiral Ganglion Neurons in Neonatally Deafened Cats: Comparison of AAV2-hBDNF and AAV5-hGDNF. J Assoc Res Otolaryngol 2019; 20:341-361. [PMID: 31222416 PMCID: PMC6646500 DOI: 10.1007/s10162-019-00723-5] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2018] [Accepted: 04/15/2019] [Indexed: 01/22/2023] Open
Abstract
Outcomes with contemporary cochlear implants (CI) depend partly upon the survival and condition of the cochlear spiral ganglion (SG) neurons. Previous studies indicate that CI stimulation can ameliorate SG neural degeneration after deafness, and brain-derived neurotrophic factor (BDNF) delivered by an osmotic pump can further improve neural survival. However, direct infusion of BDNF elicits undesirable side effects, and osmotic pumps are impractical for clinical application. In this study, we explored the potential for two adeno-associated viral vectors (AAV) to elicit targeted neurotrophic factor expression in the cochlea and promote improved SG and radial nerve fiber survival. Juvenile cats were deafened prior to hearing onset by systemic aminoglycoside injections. Auditory brainstem responses showed profound hearing loss by 16-18 days postnatal. At ~ 4 weeks of age, AAV2-GFP (green fluorescent protein), AAV5-GFP, AAV2-hBDNF, or AAV5-hGDNF (glial-derived neurotrophic factor) was injected through the round window unilaterally. For GFP immunofluorescence, animals were studied ~ 4 weeks post-injection to assess cell types transfected and their distributions. AAV2-GFP immunofluorescence demonstrated strong expression of the GFP reporter gene in residual inner (IHCs), outer hair cells (OHCs), inner pillar cells, and in some SG neurons throughout the cochlea. AAV5-GFP elicited robust transduction of IHCs and some SG neurons, but few OHCs and supporting cells. After AAV-neurotrophic factor injections, animals were studied ~ 3 months post-injection to evaluate neural survival. AAV5-hGDNF elicited a modest neurotrophic effect, with 6 % higher SG density, but had no trophic effect on radial nerve fiber survival, and undesirable ectopic fiber sprouting occurred. AAV2-hBDNF elicited a similar 6 % increase in SG survival, but also resulted in greatly improved radial nerve fiber survival, with no ectopic fiber sprouting. A further study assessed whether AAV2-hBDNF neurotrophic effects would persist over longer post-injection periods. Animals examined 6 months after virus injection showed substantial neurotrophic effects, with 14 % higher SG density and greatly improved radial nerve fiber survival. Our results suggest that AAV-neurotrophin gene therapy can elicit expression of physiological concentrations of neurotrophins in the cochlea, supporting improved SG neuronal and radial nerve fiber survival while avoiding undesirable side effects. These studies also demonstrate the potential for application of cochlear gene therapy in a large mammalian cochlea comparable to the human cochlea and in an animal model of congenital/early acquired deafness.
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19
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Scheper V, Hoffmann A, Gepp MM, Schulz A, Hamm A, Pannier C, Hubka P, Lenarz T, Schwieger J. Stem Cell Based Drug Delivery for Protection of Auditory Neurons in a Guinea Pig Model of Cochlear Implantation. Front Cell Neurosci 2019; 13:177. [PMID: 31139049 PMCID: PMC6527816 DOI: 10.3389/fncel.2019.00177] [Citation(s) in RCA: 32] [Impact Index Per Article: 6.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2019] [Accepted: 04/12/2019] [Indexed: 01/04/2023] Open
Abstract
Background: The success of a cochlear implant (CI), which is the standard therapy for patients suffering from severe to profound sensorineural hearing loss, depends on the number and excitability of spiral ganglion neurons (SGNs). Brain-derived neurotrophic factor (BDNF) has a protective effect on SGNs but should be applied chronically to guarantee their lifelong survival. Long-term administration of BDNF could be achieved using genetically modified mesenchymal stem cells (MSCs), but these cells should be protected – by ultra-high viscous (UHV-) alginate (‘alginate-MSCs’) – from the recipient immune system and from uncontrolled migration. Methods: Brain-derived neurotrophic factor-producing MSCs were encapsulated in UHV-alginate. Four experimental groups were investigated using guinea pigs as an animal model. Three of them were systemically deafened and (unilaterally) received one of the following: (I) a CI; (II) an alginate-MSC-coated CI; (III) an injection of alginate-embedded MSCs into the scala tympani followed by CI insertion and alginate polymerization. Group IV was normal hearing, with CI insertion in both ears and a unilateral injection of alginate-MSCs. Using acoustically evoked auditory brainstem response measurements, hearing thresholds were determined before implantation and before sacrificing the animals. Electrode impedance was measured weekly. Four weeks after implantation, the animals were sacrificed and the SGN density and degree of fibrosis were evaluated. Results: The MSCs survived being implanted for 4 weeks in vivo. Neither the alginate-MSC injection nor the coating affected electrode impedance or fibrosis. CI insertion with and without previous alginate injection in normal-hearing animals resulted in increased hearing thresholds within the high-frequency range. Low-frequency hearing loss was additionally observed in the alginate-injected and implanted cochleae, but not in those treated only with a CI. In deafened animals, the alginate-MSC coating of the CI significantly prevented SGN from degeneration, but the injection of alginate-MSCs did not. Conclusion: Brain-derived neurotrophic factor-producing MSCs encapsulated in UHV-alginate prevent SGNs from degeneration in the form of coating on the CI surface, but not in the form of an injection. No increase in fibrosis or impedance was detected. Further research and development aimed at verifying long-term mechanical and biological properties of coated electrodes in vitro and in vivo, in combination with chronic electrical stimulation, is needed before the current concept can be tested in clinical trials.
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Affiliation(s)
- Verena Scheper
- Department of Otolaryngology, Hannover Medical School, Hanover, Germany.,Cluster of Excellence 'Hearing4all', German Research Foundation, Bonn, Germany.,Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hanover, Germany
| | - Andrea Hoffmann
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hanover, Germany.,Department of Orthopaedic Surgery, Hannover Medical School, Hanover, Germany
| | - Michael M Gepp
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany.,Fraunhofer Project Center for Stem Cell Process Engineering, Würzburg, Germany
| | - André Schulz
- Fraunhofer Institute for Biomedical Engineering IBMT, Sulzbach, Germany
| | - Anika Hamm
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hanover, Germany.,Department of Orthopaedic Surgery, Hannover Medical School, Hanover, Germany
| | - Christoph Pannier
- Department of Otolaryngology, Hannover Medical School, Hanover, Germany
| | - Peter Hubka
- Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hanover, Germany.,Department of Experimental Otology, Hannover Medical School, Hanover, Germany
| | - Thomas Lenarz
- Department of Otolaryngology, Hannover Medical School, Hanover, Germany.,Cluster of Excellence 'Hearing4all', German Research Foundation, Bonn, Germany.,Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hanover, Germany
| | - Jana Schwieger
- Department of Otolaryngology, Hannover Medical School, Hanover, Germany.,Lower Saxony Centre for Biomedical Engineering, Implant Research and Development (NIFE), Hanover, Germany
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20
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Ma Y, Wise AK, Shepherd RK, Richardson RT. New molecular therapies for the treatment of hearing loss. Pharmacol Ther 2019; 200:190-209. [PMID: 31075354 DOI: 10.1016/j.pharmthera.2019.05.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 05/02/2019] [Indexed: 12/11/2022]
Abstract
An estimated 466 million people suffer from hearing loss worldwide. Sensorineural hearing loss is characterized by degeneration of key structures of the sensory pathway in the cochlea such as the sensory hair cells, the primary auditory neurons and their synaptic connection to the hair cells - the ribbon synapse. Various strategies to protect or regenerate these sensory cells and structures are the subject of intensive research. Yet despite recent advances in our understandings of the capacity of the cochlea for repair and regeneration there are currently no pharmacological or biological interventions for hearing loss. Current research focusses on localized cochlear drug, gene and cell-based therapies. One of the more promising drug-based therapies is based on neurotrophic factors for the repair of the ribbon synapse after noise exposure, as well as preventing loss of primary auditory neurons and regrowth of the auditory neuron fibers after severe hearing loss. Drug therapy delivery technologies are being employed to address the specific needs of neurotrophin and other therapies for hearing loss that include the need for high doses, long-term delivery, localised or cell-specific targeting and techniques for their safe and efficacious delivery to the cochlea. Novel biomaterials are enabling high payloads of drugs to be administered to the cochlea with subsequent slow-release properties that are proving to be beneficial for treating hearing loss. In parallel, new gene therapy technologies are addressing the need for cell specificity and high efficacy for the treatment of both genetic and acquired hearing loss with promising reports of hearing recovery. Some biomaterials and cell therapies are being used in conjunction with the cochlear implant ensuring therapeutic benefit to the primary neurons during electrical stimulation. This review will introduce the auditory system, hearing loss and the potential for repair and regeneration in the cochlea. Drug delivery to the cochlea will then be reviewed, with a focus on new biomaterials, gene therapy technologies, cell therapy and the use of the cochlear implant as a vehicle for drug delivery. With the current pre-clinical research effort into therapies for hearing loss, including clinical trials for gene therapy, the future for the treatment for hearing loss is looking bright.
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Affiliation(s)
- Yutian Ma
- Bionics Institute, East Melbourne, Australia; ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Australia; University of Melbourne, Department of Chemical Engineering, Parkville, Victoria, Australia
| | - Andrew K Wise
- Bionics Institute, East Melbourne, Australia; University of Melbourne, Medical Bionics Department, East Melbourne, Australia; University of Melbourne, Department of Surgery - Otolaryngology, East Melbourne, Australia
| | - Robert K Shepherd
- Bionics Institute, East Melbourne, Australia; University of Melbourne, Medical Bionics Department, East Melbourne, Australia; University of Melbourne, Department of Surgery - Otolaryngology, East Melbourne, Australia
| | - Rachael T Richardson
- Bionics Institute, East Melbourne, Australia; University of Melbourne, Medical Bionics Department, East Melbourne, Australia; University of Melbourne, Department of Surgery - Otolaryngology, East Melbourne, Australia.
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21
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Welch C, Dillon MT, Pillsbury HC. Electric and Acoustic Stimulation in Cochlear Implant Recipients with Hearing Preservation. Semin Hear 2018; 39:414-427. [PMID: 30374212 PMCID: PMC6203459 DOI: 10.1055/s-0038-1670707] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/28/2022] Open
Abstract
Hearing loss affects 30 million people in the United States, and a subset of these patients have normal low-frequency hearing and ski-sloped high-frequency hearing loss. For these patients, hearing aids alone may not provide adequate benefit. Cochlear implantation alone has been utilized to improve speech perception. The addition of high-frequency electric hearing to low-frequency acoustic hearing in these patients is beneficial. Technical improvements have allowed preservation of low-frequency hearing in cochlear implant recipients, allowing for electric and acoustic stimulation in the same ear with significant improvements in speech perception, sound localization, music appreciation, and quality of life.
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Affiliation(s)
- Christopher Welch
- Department of Otolaryngology/Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Margaret T. Dillon
- Department of Otolaryngology/Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
| | - Harold C. Pillsbury
- Department of Otolaryngology/Head and Neck Surgery, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina
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22
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Akil O, Blits B, Lustig LR, Leake PA. Virally Mediated Overexpression of Glial-Derived Neurotrophic Factor Elicits Age- and Dose-Dependent Neuronal Toxicity and Hearing Loss. Hum Gene Ther 2018; 30:88-105. [PMID: 30183384 DOI: 10.1089/hum.2018.028] [Citation(s) in RCA: 20] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Contemporary cochlear implants (CI) are generally very effective for remediation of severe to profound sensorineural hearing loss, but outcomes are still highly variable. Auditory nerve survival is likely one of the major factors underlying this variability. Neurotrophin therapy therefore has been proposed for CI recipients, with the goal of improving outcomes by promoting improved survival of cochlear spiral ganglion neurons (SGN) and/or residual hair cells. Previous studies have shown that glial-derived neurotrophic factor (GDNF), brain-derived neurotrophic factor, and neurotrophin-3 can rescue SGNs following insult. The current study was designed to determine whether adeno-associated virus vector serotype 5 (AAV-5) encoding either green fluorescent protein or GDNF can transduce cells in the mouse cochlea to express useful levels of neurotrophin and to approximate the optimum therapeutic dose(s) for transducing hair cells and SGN. The findings demonstrate that AAV-5 is a potentially useful gene therapy vector for the cochlea, resulting in extremely high levels of transgene expression in the cochlear inner hair cells and SGN. However, overexpression of human GDNF in newborn mice caused severe neurological symptoms and hearing loss, likely due to Purkinje cell loss and cochlear nucleus pathology. Thus, extremely high levels of transgene protein expression should be avoided, particularly for proteins that have neurological function in neonatal subjects.
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Affiliation(s)
- Omar Akil
- 1 Department of Otolaryngology-Head and Neck Surgery, University of California, San Francisco, San Francisco, California
| | - Bas Blits
- 2 Department of Research and Development, UniQure Biopharma B.V., Amsterdam, The Netherlands
| | - Lawrence R Lustig
- 3 Department of Otolaryngology-Head and Neck Surgery, Columbia University Medical Center, New York, New York
| | - Patricia A Leake
- 1 Department of Otolaryngology-Head and Neck Surgery, University of California, San Francisco, San Francisco, California
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23
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Shepherd RK, Wise AK, Enke YL, Carter PM, Fallon JB. Evaluation of focused multipolar stimulation for cochlear implants: a preclinical safety study. J Neural Eng 2018; 14:046020. [PMID: 28607224 DOI: 10.1088/1741-2552/aa7586] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023]
Abstract
OBJECTIVE Cochlear implants (CIs) have a limited number of independent stimulation channels due to the highly conductive nature of the fluid-filled cochlea. Attempts to develop highly focused stimulation to improve speech perception in CI users includes the use of simultaneous stimulation via multiple current sources. Focused multipolar (FMP) stimulation is an example of this approach and has been shown to reduce interaction between stimulating channels. However, compared with conventional biphasic current pulses generated from a single current source, FMP is a complex stimulus that includes extended periods of stimulation before charge recovery is achieved, raising questions on whether chronic stimulation with this strategy is safe. The present study evaluated the long-term safety of intracochlear stimulation using FMP in a preclinical animal model of profound deafness. APPROACH Six cats were bilaterally implanted with scala tympani electrode arrays two months after deafening, and received continuous unilateral FMP stimulation at levels that evoked a behavioural response for periods of up to 182 d. Electrode impedance, electrically-evoked compound action potentials (ECAPs) and auditory brainstem responses (EABRs) were monitored periodically over the course of the stimulation program from both the stimulated and contralateral control cochleae. On completion of the stimulation program cochleae were examined histologically and the electrode arrays were evaluated for evidence of platinum (Pt) corrosion. MAIN RESULTS There was no significant difference in electrode impedance between control and chronically stimulated electrodes following long-term FMP stimulation. Moreover, there was no significant difference between ECAP and EABR thresholds evoked from control or stimulated cochleae at either the onset of stimulation or at completion of the stimulation program. Chronic FMP stimulation had no effect on spiral ganglion neuron (SGN) survival when compared with unstimulated control cochleae. Long-term implantation typically evoked a mild foreign body reaction proximal to the electrode array; however stimulated cochleae exhibited a small but statistically significant increase in the tissue response. Finally, there was no evidence of Pt corrosion following long-term FMP stimulation; stimulated electrodes exhibited the same surface features as the unstimulated control electrodes. SIGNIFICANCE Chronic intracochlear FMP stimulation at levels used in the present study did not adversely affect electrically-evoked neural thresholds or SGN survival but evoked a small, benign increase in inflammatory response compared to control ears. Moreover chronic FMP stimulation does not affect the surface of Pt electrodes at suprathreshold stimulus levels. These findings support the safe clinical application of an FMP stimulation strategy.
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Affiliation(s)
- Robert K Shepherd
- The Bionics Institute, East Melbourne 3002, Australia. Department of Medical Bionics, University of Melbourne, East Melbourne 3002, Australia
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24
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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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Schendzielorz P, Vollmer M, Rak K, Wiegner A, Nada N, Radeloff K, Hagen R, Radeloff A. Adipose-derived stromal cells enhance auditory neuron survival in an animal model of sensory hearing loss. Cytotherapy 2017; 19:1197-1207. [DOI: 10.1016/j.jcyt.2017.07.007] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/14/2016] [Revised: 07/17/2017] [Accepted: 07/18/2017] [Indexed: 12/27/2022]
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Regenerative medicine in hearing recovery. Cytotherapy 2017; 19:909-915. [DOI: 10.1016/j.jcyt.2017.04.008] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/20/2017] [Revised: 03/24/2017] [Accepted: 04/21/2017] [Indexed: 12/20/2022]
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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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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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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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Sandrof MA, Emerich DF, Thanos CG. Primary Choroid Plexus Tissue for Use in Cellular Therapy. Methods Mol Biol 2017; 1479:237-249. [PMID: 27738941 DOI: 10.1007/978-1-4939-6364-5_19] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The choroid plexus (CP) has been explored as a cellular therapeutic due to its broad-ranging secretome and demonstrated longevity in a variety of encapsulation modalities. While the CP organ is normally involved in disease repair processes in the brain, the range of indications that could potentially be ameliorated with exogenous CP therapy is widespread, including diseases of the central nervous system, hearing loss, chronic wounds, and others. The CP can be isolated from animal sources and digested into a highly purified epithelial culture that can withstand encapsulation and transplantation. Its epithelium can adapt to different microenvironments, and depending on culture conditions, can be manipulated into various three-dimensional configurations with distinct gene expression profiles. The cocktail of proteins secreted by the CP can be harvested in culture, and purified forms of these extracts have been evaluated in topical applications to treat poorly healing wounds. When encapsulated, the epithelial clusters can be maintained for extended durations in vitro with minimal impact on potency. A treatment for Parkinson's disease utilizing encapsulated porcine CP has been developed and is currently being evaluated in a Phase I clinical trial. The current chapter serves to summarize recent experience with CP factor delivery, and provides a description of the relevant materials and methods employed in these studies.
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Affiliation(s)
- M A Sandrof
- Cytosolv, Inc., 117 Chapman Street, Suite 107, Providence, RI, 02905, USA
| | | | - Chris G Thanos
- Cytosolv, Inc., 117 Chapman Street, Suite 107, Providence, RI, 02905, USA.
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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: 53] [Impact Index Per Article: 6.6] [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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Frick C, Müller M, Wank U, Tropitzsch A, Kramer B, Senn P, Rask-Andersen H, Wiesmüller KH, Löwenheim H. Biofunctionalized peptide-based hydrogels provide permissive scaffolds to attract neurite outgrowth from spiral ganglion neurons. Colloids Surf B Biointerfaces 2016; 149:105-114. [PMID: 27736723 DOI: 10.1016/j.colsurfb.2016.10.003] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/24/2016] [Revised: 09/03/2016] [Accepted: 10/03/2016] [Indexed: 12/15/2022]
Abstract
Cochlear implants (CI) allow for hearing rehabilitation in patients with sensorineural hearing loss or deafness. Restricted CI performance results from the spatial gap between spiral ganglion neurons and the CI, causing current spread that limits spatially restricted stimulation and impairs frequency resolution. This may be substantially improved by guiding peripheral processes of spiral ganglion neurons towards and onto the CI electrode contacts. An injectable, peptide-based hydrogel was developed which may provide a permissive scaffold to facilitate neurite growth towards the CI. To test hydrogel capacity to attract spiral ganglion neurites, neurite outgrowth was quantified in an in vitro model using a custom-designed hydrogel scaffold and PuraMatrix®. Neurite attachment to native hydrogels is poor, but significantly improved by incorporation of brain-derived neurotrophic factor (BDNF), covalent coupling of the bioactive laminin epitope IKVAV and the incorporation a full length laminin to hydrogel scaffolds. Incorporation of full length laminin protein into a novel custom-designed biofunctionalized hydrogel (IKVAV-GGG-SIINFEKL) allows for neurite outgrowth into the hydrogel scaffold. The study demonstrates that peptide-based hydrogels can be specifically biofunctionalized to provide a permissive scaffold to attract neurite outgrowth from spiral ganglion neurons. Such biomaterials appear suitable to bridge the spatial gap between neurons and the CI.
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Affiliation(s)
- Claudia Frick
- Department of Otolaryngology, Head and Neck Surgery, Tübingen Hearing Research Centre, Eberhard Karls University Tübingen, DE-72076 Tübingen, Germany.
| | - Marcus Müller
- Department of Otolaryngology, Head and Neck Surgery, Tübingen Hearing Research Centre, Eberhard Karls University Tübingen, DE-72076 Tübingen, Germany.
| | - Ute Wank
- EMC microcollections GmbH, DE-72070 Tübingen, Germany.
| | - Anke Tropitzsch
- Department of Otolaryngology, Head and Neck Surgery, Tübingen Hearing Research Centre, Eberhard Karls University Tübingen, DE-72076 Tübingen, Germany.
| | - Benedikt Kramer
- Department of Otolaryngology, Head and Neck Surgery, Tübingen Hearing Research Centre, Eberhard Karls University Tübingen, DE-72076 Tübingen, Germany.
| | - Pascal Senn
- Department of Clinical Neurosciences, Service of Otorhinolaryngology, Head & Neck Surgery, HUG, University Hospital of Geneva, CH-1211 Genève 14, Switzerland.
| | - Helge Rask-Andersen
- Department of Surgical Sciences, Head and Neck Surgery, Section of Otolaryngology, Uppsala University Hospital, Departments of Otolaryngology, Uppsala University Hospital, SE-751 85 Uppsala, Sweden.
| | | | - Hubert Löwenheim
- Department of Otolaryngology, Head and Neck Surgery, Tübingen Hearing Research Centre, Eberhard Karls University Tübingen, DE-72076 Tübingen, Germany.
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Hahnewald S, Tscherter A, Marconi E, Streit J, Widmer HR, Garnham C, Benav H, Mueller M, Löwenheim H, Roccio M, Senn P. Response profiles of murine spiral ganglion neurons on multi-electrode arrays. J Neural Eng 2015; 13:016011. [PMID: 26656212 DOI: 10.1088/1741-2560/13/1/016011] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
OBJECTIVE Cochlear implants (CIs) have become the gold standard treatment for deafness. These neuroprosthetic devices feature a linear electrode array, surgically inserted into the cochlea, and function by directly stimulating the auditory neurons located within the spiral ganglion, bypassing lost or not-functioning hair cells. Despite their success, some limitations still remain, including poor frequency resolution and high-energy consumption. In both cases, the anatomical gap between the electrode array and the spiral ganglion neurons (SGNs) is believed to be an important limiting factor. The final goal of the study is to characterize response profiles of SGNs growing in intimate contact with an electrode array, in view of designing novel CI devices and stimulation protocols, featuring a gapless interface with auditory neurons. APPROACH We have characterized SGN responses to extracellular stimulation using multi-electrode arrays (MEAs). This setup allows, in our view, to optimize in vitro many of the limiting interface aspects between CIs and SGNs. MAIN RESULTS Early postnatal mouse SGN explants were analyzed after 6-18 days in culture. Different stimulation protocols were compared with the aim to lower the stimulation threshold and the energy needed to elicit a response. In the best case, a four-fold reduction of the energy was obtained by lengthening the biphasic stimulus from 40 μs to 160 μs. Similarly, quasi monophasic pulses were more effective than biphasic pulses and the insertion of an interphase gap moderately improved efficiency. Finally, the stimulation with an external electrode mounted on a micromanipulator showed that the energy needed to elicit a response could be reduced by a factor of five with decreasing its distance from 40 μm to 0 μm from the auditory neurons. SIGNIFICANCE This study is the first to show electrical activity of SGNs on MEAs. Our findings may help to improve stimulation by and to reduce energy consumption of CIs and thereby contribute to the development of fully implantable devices with better auditory resolution in the future.
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Affiliation(s)
- Stefan Hahnewald
- Inner Ear Research Laboratory, University Departments of Clinical Research and Otorhinolaryngology, Head & Neck Surgery, Inselspital, University of Bern, Switzerland. Regenerative Neuroscience Cluster, Department of Clinical Research, University of Bern, Switzerland
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Temporary Neurotrophin Treatment Prevents Deafness-Induced Auditory Nerve Degeneration and Preserves Function. J Neurosci 2015; 35:12331-45. [PMID: 26354903 DOI: 10.1523/jneurosci.0096-15.2015] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
After substantial loss of cochlear hair cells, exogenous neurotrophins prevent degeneration of the auditory nerve. Because cochlear implantation, the current therapy for profound sensorineural hearing loss, depends on a functional nerve, application of neurotrophins is being investigated. We addressed two questions important for fundamental insight into the effects of exogenous neurotrophins on a degenerating neural system, and for translation to the clinic. First, does temporary treatment with brain-derived neurotrophic factor (BDNF) prevent nerve degeneration on the long term? Second, how does a BDNF-treated nerve respond to electrical stimulation? Deafened guinea pigs received a cochlear implant, and their cochleas were infused with BDNF for 4 weeks. Up to 8 weeks after treatment, their cochleas were analyzed histologically. Electrically evoked compound action potentials (eCAPs) were recorded using stimulation paradigms that are informative of neural survival. Spiral ganglion cell (SGC) degeneration was prevented during BDNF treatment, resulting in 1.9 times more SGCs than in deafened untreated cochleas. Importantly, SGC survival was almost complete 8 weeks after treatment cessation, when 2.6 times more SGCs were observed. In four eCAP characteristics (three involving alteration of the interphase gap of the biphasic current pulse and one involving pulse trains), we found large and statistically significant differences between normal-hearing and deaf controls. Importantly, for BDNF-treated animals, these eCAP characteristics were near normal, suggesting healthy responsiveness of BDNF-treated SGCs. In conclusion, clinically practicable short-term neurotrophin treatment is sufficient for long-term survival of SGCs, and it can restore or preserve SGC function well beyond the treatment period. Significance statement: Successful restoration of hearing in deaf subjects by means of a cochlear implant requires a healthy spiral ganglion cell population. Deafness-induced degeneration of these cells can be averted with neurotrophic factors. In the present study in deafened guinea pigs, we investigated the long-term effects of temporary (i.e., clinically practicable) treatment with brain-derived neurotrophic factor (BDNF). We show that, after treatment cessation, the neuroprotective effect remains for at least 8 weeks. Moreover, for the first time, it is shown that the electrical responsiveness of BDNF-treated spiral ganglion cells is preserved during this period as well. These findings demonstrate that treatment of the auditory nerve with neurotrophic factors may be relevant for cochlear implant users.
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Gillespie LN, Richardson RT, Nayagam BA, Wise AK. Treating hearing disorders with cell and gene therapy. J Neural Eng 2015; 11:065001. [PMID: 25420002 DOI: 10.1088/1741-2560/11/6/065001] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Hearing loss is an increasing problem for a substantial number of people and, with an aging population, the incidence and severity of hearing loss will become more significant over time. There are very few therapies currently available to treat hearing loss, and so the development of new therapeutic strategies for hearing impaired individuals is of paramount importance to address this unmet clinical need. Most forms of hearing loss are progressive in nature and therefore an opportunity exists to develop novel therapeutic approaches to slow or halt hearing loss progression, or even repair or replace lost hearing function. Numerous emerging technologies have potential as therapeutic options. This paper details the potential of cell- and gene-based therapies to provide therapeutic agents to protect sensory and neural cells from various insults known to cause hearing loss; explores the potential of replacing lost sensory and nerve cells using gene and stem cell therapy; and describes the considerations for clinical translation and the challenges that need to be overcome.
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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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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: 20] [Impact Index Per Article: 2.2] [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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Stoppel WL, Ghezzi CE, McNamara SL, Black LD, Kaplan DL. Clinical applications of naturally derived biopolymer-based scaffolds for regenerative medicine. Ann Biomed Eng 2015; 43:657-80. [PMID: 25537688 PMCID: PMC8196399 DOI: 10.1007/s10439-014-1206-2] [Citation(s) in RCA: 91] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2014] [Accepted: 11/26/2014] [Indexed: 01/05/2023]
Abstract
Naturally derived polymeric biomaterials, such as collagens, silks, elastins, alginates, and fibrins are utilized in tissue engineering due to their biocompatibility, bioactivity, and tunable mechanical and degradation kinetics. The use of these natural biopolymers in biomedical applications is advantageous because they do not release cytotoxic degradation products, are often processed using environmentally-friendly aqueous-based methods, and their degradation rates within biological systems can be manipulated by modifying the starting formulation or processing conditions. For these reasons, many recent in vivo investigations and FDA-approval of new biomaterials for clinical use have utilized natural biopolymers as matrices for cell delivery and as scaffolds for cell-free support of native tissues. This review highlights biopolymer-based scaffolds used in clinical applications for the regeneration and repair of native tissues, with a focus on bone, skeletal muscle, peripheral nerve, cardiac muscle, and cornea substitutes.
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Affiliation(s)
- Whitney L. Stoppel
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA
| | - Chiara E. Ghezzi
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA
| | - Stephanie L. McNamara
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA
- Cellular, Molecular and Developmental Biology Program, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA 02111, USA
- The Harvard/MIT MD-PhD Program, Harvard Medical School, Boston, MA 02115, USA
| | - Lauren D. Black
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA
- Cellular, Molecular and Developmental Biology Program, Sackler School of Graduate Biomedical Sciences, Tufts University School of Medicine, Boston, MA 02111, USA
| | - David L. Kaplan
- Department of Biomedical Engineering, Tufts University, Medford, MA 02155, USA
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Cell-based neurotrophin treatment supports long-term auditory neuron survival in the deaf guinea pig. J Control Release 2015; 198:26-34. [DOI: 10.1016/j.jconrel.2014.11.026] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2014] [Accepted: 11/25/2014] [Indexed: 12/16/2022]
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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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Electroacoustic stimulation: now and into the future. BIOMED RESEARCH INTERNATIONAL 2014; 2014:350504. [PMID: 25276779 PMCID: PMC4168031 DOI: 10.1155/2014/350504] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/16/2014] [Accepted: 08/04/2014] [Indexed: 12/22/2022]
Abstract
Cochlear implants have provided hearing to hundreds of thousands of profoundly deaf people around the world. Recently, the eligibility criteria for cochlear implantation have been relaxed to include individuals who have some useful residual hearing. These recipients receive inputs from both electric and acoustic stimulation (EAS). Implant recipients who can combine these hearing modalities demonstrate pronounced benefit in speech perception, listening in background noise, and music appreciation over implant recipients that rely on electrical stimulation alone. The mechanisms bestowing this benefit are unknown, but it is likely that interaction of the electric and acoustic signals in the auditory pathway plays a role. Protection of residual hearing both during and following cochlear implantation is critical for EAS. A number of surgical refinements have been implemented to protect residual hearing, and the development of hearing-protective drug and gene therapies is promising for EAS recipients. This review outlines the current field of EAS, with a focus on interactions that are observed between these modalities in animal models. It also outlines current trends in EAS surgery and gives an overview of the drug and gene therapies that are clinically translatable and may one day provide protection of residual hearing for cochlear implant recipients.
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Zanin MP, Hellström M, Shepherd RK, Harvey AR, Gillespie LN. Development of a cell-based treatment for long-term neurotrophin expression and spiral ganglion neuron survival. Neuroscience 2014; 277:690-9. [PMID: 25088914 DOI: 10.1016/j.neuroscience.2014.07.044] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2014] [Revised: 06/13/2014] [Accepted: 07/18/2014] [Indexed: 12/13/2022]
Abstract
Spiral ganglion neurons (SGNs), the target cells of the cochlear implant, undergo gradual degeneration following loss of the sensory epithelium in deafness. The preservation of a viable population of SGNs in deafness can be achieved in animal models with exogenous application of neurotrophins such as brain-derived neurotrophic factor (BDNF) and neurotrophin-3. For translation into clinical application, a suitable delivery strategy that provides ongoing neurotrophic support and promotes long-term SGN survival is required. Cell-based neurotrophin treatment has the potential to meet the specific requirements for clinical application, and we have previously reported that Schwann cells genetically modified to express BDNF can support SGN survival in deafness for 4 weeks. This study aimed to investigate various parameters important for the development of a long-term cell-based neurotrophin treatment to support SGN survival. Specifically, we investigated different (i) cell types, (ii) gene transfer methods and (iii) neurotrophins, in order to determine which variables may provide long-term neurotrophin expression and which, therefore, may be the most effective for supporting long-term SGN survival in vivo. We found that fibroblasts that were nucleofected to express BDNF provided the most sustained neurotrophin expression, with ongoing BDNF expression for at least 30 weeks. In addition, the secreted neurotrophin was biologically active and elicited survival effects on SGNs in vitro. Nucleofected fibroblasts may therefore represent a method for safe, long-term delivery of neurotrophins to the deafened cochlea to support SGN survival in deafness.
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Affiliation(s)
- M P Zanin
- Bionics Institute, Melbourne, Australia
| | - M Hellström
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, Australia
| | - R K Shepherd
- Bionics Institute, Melbourne, Australia; Department of Medical Bionics, University of Melbourne, Australia
| | - A R Harvey
- School of Anatomy, Physiology and Human Biology, The University of Western Australia, Australia
| | - L N Gillespie
- Bionics Institute, Melbourne, Australia; Department of Medical Bionics, University of Melbourne, Australia.
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Irving S, Wise AK, Millard RE, Shepherd RK, Fallon JB. A partial hearing animal model for chronic electro-acoustic stimulation. J Neural Eng 2014; 11:046008. [PMID: 24921595 PMCID: PMC4116305 DOI: 10.1088/1741-2560/11/4/046008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
OBJECTIVE Cochlear implants (CIs) have provided some auditory function to hundreds of thousands of people around the world. Although traditionally carried out only in profoundly deaf patients, the eligibility criteria for implantation have recently been relaxed to include many partially-deaf patients with useful levels of hearing. These patients receive both electrical stimulation from their implant and acoustic stimulation via their residual hearing (electro-acoustic stimulation; EAS) and perform very well. It is unclear how EAS improves speech perception over electrical stimulation alone, and little evidence exists about the nature of the interactions between electric and acoustic stimuli. Furthermore, clinical results suggest that some patients that undergo cochlear implantation lose some, if not all, of their residual hearing, reducing the advantages of EAS over electrical stimulation alone. A reliable animal model with clinically-relevant partial deafness combined with clinical CIs is important to enable these issues to be studied. This paper outlines such a model that has been successfully used in our laboratory. APPROACH This paper outlines a battery of techniques used in our laboratory to generate, validate and examine an animal model of partial deafness and chronic CI use. MAIN RESULTS Ototoxic deafening produced bilaterally symmetrical hearing thresholds in neonatal and adult animals. Electrical activation of the auditory system was confirmed, and all animals were chronically stimulated via adapted clinical CIs. Acoustic compound action potentials (CAPs) were obtained from partially-hearing cochleae, using the CI amplifier. Immunohistochemical analysis allows the effects of deafness and electrical stimulation on cell survival to be studied. SIGNIFICANCE This animal model has applications in EAS research, including investigating the functional interactions between electric and acoustic stimulation, and the development of techniques to maintain residual hearing following cochlear implantation. The ability to record CAPs via the CI has clinical direct relevance for obtaining objective measures of residual hearing.
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Affiliation(s)
- S Irving
- Bionics Institute, Melbourne, Australia. University of Melbourne, Melbourne, Australia
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Bolos M, Antequera D, Aldudo J, Kristen H, Bullido MJ, Carro E. Choroid plexus implants rescue Alzheimer's disease-like pathologies by modulating amyloid-β degradation. Cell Mol Life Sci 2014; 71:2947-55. [PMID: 24343520 PMCID: PMC11113864 DOI: 10.1007/s00018-013-1529-4] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2013] [Revised: 09/13/2013] [Accepted: 11/19/2013] [Indexed: 12/31/2022]
Abstract
The choroid plexuses (CP) release numerous biologically active enzymes and neurotrophic factors, and contain a subpopulation of neural progenitor cells providing the capacity to proliferate and differentiate into other types of cells. These characteristics make CP epithelial cells (CPECs) excellent candidates for cell therapy aiming at restoring brain tissue in neurodegenerative illnesses, including Alzheimer's disease (AD). In the present study, using in vitro approaches, we demonstrated that CP were able to diminish amyloid-β (Aβ) levels in cell cultures, reducing Aβ-induced neurotoxicity. For in vivo studies, CPECs were transplanted into the brain of the APP/PS1 murine model of AD that exhibits advanced Aβ accumulation and memory impairment. Brain examination after cell implantation revealed a significant reduction in brain Aβ deposits, hyperphosphorylation of tau, and astrocytic reactivity. Remarkably, the transplantation of CPECs was accompanied by a total behavioral recovery in APP/PS1 mice, improving spatial and non-spatial memory. These findings reinforce the neuroprotective potential of CPECs and the use of cell therapies as useful tools in AD.
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Affiliation(s)
- Marta Bolos
- Neuroscience Group, Instituto de Investigacion Hospital 12 de Octubre (i+12), Av. de Córdoba s/n, 28041 Madrid, Spain
- Center for Networker Biomedical Research in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
| | - Desireé Antequera
- Neuroscience Group, Instituto de Investigacion Hospital 12 de Octubre (i+12), Av. de Córdoba s/n, 28041 Madrid, Spain
- Center for Networker Biomedical Research in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
| | - Jesús Aldudo
- Center for Networker Biomedical Research in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
- Centro de Biología Molecular Severo Ochoa, CBM (UAM/CSIC), Madrid, Spain
| | - Henrike Kristen
- Centro de Biología Molecular Severo Ochoa, CBM (UAM/CSIC), Madrid, Spain
| | - María Jesús Bullido
- Center for Networker Biomedical Research in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
- Centro de Biología Molecular Severo Ochoa, CBM (UAM/CSIC), Madrid, Spain
| | - Eva Carro
- Neuroscience Group, Instituto de Investigacion Hospital 12 de Octubre (i+12), Av. de Córdoba s/n, 28041 Madrid, Spain
- Center for Networker Biomedical Research in Neurodegenerative Diseases (CIBERNED), Madrid, Spain
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Carriers in cell-based therapies for neurological disorders. Int J Mol Sci 2014; 15:10669-723. [PMID: 24933636 PMCID: PMC4100175 DOI: 10.3390/ijms150610669] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/14/2014] [Revised: 05/19/2014] [Accepted: 05/30/2014] [Indexed: 02/07/2023] Open
Abstract
There is a pressing need for long-term neuroprotective and neuroregenerative therapies to promote full function recovery of injuries in the human nervous system resulting from trauma, stroke or degenerative diseases. Although cell-based therapies are promising in supporting repair and regeneration, direct introduction to the injury site is plagued by problems such as low transplanted cell survival rate, limited graft integration, immunorejection, and tumor formation. Neural tissue engineering offers an integrative and multifaceted approach to tackle these complex neurological disorders. Synergistic therapeutic effects can be obtained from combining customized biomaterial scaffolds with cell-based therapies. Current scaffold-facilitated cell transplantation strategies aim to achieve structural and functional rescue via offering a three-dimensional permissive and instructive environment for sustainable neuroactive factor production for prolonged periods and/or cell replacement at the target site. In this review, we intend to highlight important considerations in biomaterial selection and to review major biodegradable or non-biodegradable scaffolds used for cell transplantation to the central and peripheral nervous system in preclinical and clinical trials. Expanded knowledge in biomaterial properties and their prolonged interaction with transplanted and host cells have greatly expanded the possibilities for designing suitable carrier systems and the potential of cell therapies in the nervous system.
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Atkinson PJ, Wise AK, Flynn BO, Nayagam BA, Richardson RT. Viability of long-term gene therapy in the cochlea. Sci Rep 2014; 4:4733. [PMID: 24751795 PMCID: PMC3994438 DOI: 10.1038/srep04733] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 04/01/2014] [Indexed: 12/16/2022] Open
Abstract
Gene therapy has been investigated as a way to introduce a variety of genes to treat neurological disorders. An important clinical consideration is its long-term effectiveness. This research aims to study the long-term expression and effectiveness of gene therapy in promoting spiral ganglion neuron survival after deafness. Adenoviral vectors modified to express brain derived neurotrophic factor or neurotrophin-3 were unilaterally injected into the guinea pig cochlea one week post ototoxic deafening. After six months, persistence of gene expression and significantly greater neuronal survival in neurotrophin-treated cochleae compared to the contralateral cochleae were observed. The long-term gene expression observed indicates that gene therapy is potentially viable; however the degeneration of the transduced cells as a result of the original ototoxic insult may limit clinical effectiveness. With further research aimed at transducing stable cochlear cells, gene therapy may be an efficacious way to introduce neurotrophins to promote neuronal survival after hearing loss.
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Affiliation(s)
- Patrick J Atkinson
- 1] Bionics Institute, East Melbourne, Victoria, Australia [2] Department of Otolaryngology, University of Melbourne, East Melbourne, Victoria, Australia
| | - Andrew K Wise
- 1] Bionics Institute, East Melbourne, Victoria, Australia [2] Department of Otolaryngology, University of Melbourne, East Melbourne, Victoria, Australia [3] Department of Medical Bionics, University of Melbourne, East Melbourne, Victoria, Australia
| | | | - Bryony A Nayagam
- 1] Bionics Institute, East Melbourne, Victoria, Australia [2] Department of Audiology and Speech Pathology, University of Melbourne, Parkville, Victoria, Australia
| | - Rachael T Richardson
- 1] Bionics Institute, East Melbourne, Victoria, Australia [2] Department of Otolaryngology, University of Melbourne, East Melbourne, Victoria, Australia [3] Department of Medical Bionics, University of Melbourne, East Melbourne, Victoria, Australia
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Landry TG, Fallon JB, Wise AK, Shepherd RK. Chronic neurotrophin delivery promotes ectopic neurite growth from the spiral ganglion of deafened cochleae without compromising the spatial selectivity of cochlear implants. J Comp Neurol 2014; 521:2818-32. [PMID: 23436344 DOI: 10.1002/cne.23318] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2012] [Accepted: 02/05/2013] [Indexed: 12/25/2022]
Abstract
Cochlear implants restore hearing cues in the severe-profoundly deaf by electrically stimulating spiral ganglion neurons (SGNs). However, SGNs degenerate following loss of cochlear hair cells, due at least in part to a reduction in the endogenous neurotrophin (NT) supply, normally provided by hair cells and supporting cells of the organ of Corti. Delivering exogenous NTs to the cochlea can rescue SGNs from degeneration and can also promote the ectopic growth of SGN neurites. This resprouting may disrupt the cochleotopic organization upon which cochlear implants rely to impart pitch cues. Using retrograde labeling and confocal imaging of SGNs, we determined the extent of neurite growth following 28 days of exogenous NT treatment in deafened guinea pigs with and without chronic electrical stimulation (ES). On completion of this treatment, we measured the spread of neural activation to intracochlear ES by recording neural responses across the cochleotopically organized inferior colliculus using multichannel recording techniques. Although NT treatment significantly increased both the length and the lateral extent of growth of neurites along the cochlea compared with deafened controls, these anatomical changes did not affect the spread of neural activation when examined immediately after 28 days of NT treatment. NT treatment did, however, result in lower excitation thresholds compared with deafened controls. These data support the application of NTs for improved clinical outcomes for cochlear implant patients.
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Affiliation(s)
- Thomas G Landry
- The Bionics Institute, East Melbourne, Victoria 3002, Australia
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Irving S, Trotter MI, Fallon JB, Millard RE, Shepherd RK, Wise AK. Cochlear implantation for chronic electrical stimulation in the mouse. Hear Res 2013; 306:37-45. [PMID: 24055621 DOI: 10.1016/j.heares.2013.09.005] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/31/2013] [Revised: 08/23/2013] [Accepted: 09/09/2013] [Indexed: 01/02/2023]
Abstract
The mouse is becoming an increasingly attractive model for auditory research due to the number of genetic deafness models available. These genetic models offer the researcher an array of congenital causes of hearing impairment, and are therefore of high clinical relevance. To date, the use of mice in cochlear implant research has not been possible due to the lack of an intracochlear electrode array and stimulator small enough for murine use, coupled with the difficulty of the surgery in this species. Here, we present a fully-implantable intracochlear electrode stimulator assembly designed for chronic implantation in the mouse. We describe the surgical approach for implantation, as well as presenting the first functional data obtained from intracochlear electrical stimulation in the mouse.
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Affiliation(s)
- S Irving
- Bionics Institute, Melbourne, Australia; Department of Psychology, University of Melbourne, Australia
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Wrzeszcz A, Reuter G, Nolte I, Lenarz T, Scheper V. Spiral ganglion neuron quantification in the guinea pig cochlea using Confocal Laser Scanning Microscopy compared to embedding methods. Hear Res 2013; 306:145-55. [PMID: 23968822 DOI: 10.1016/j.heares.2013.08.002] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/13/2013] [Revised: 07/10/2013] [Accepted: 08/06/2013] [Indexed: 12/16/2022]
Abstract
Neuron counting in the cochlea is a crucial but time-consuming operation for which various methods have been developed. To improve simplicity and efficiency, we tested an imaging method of the cochlea, and based on Confocal Laser Scanning Microscopy (CLSM), we visualised Rosenthal's Canal and quantified the spiral ganglion neurons (SGN) within. Cochleae of 8 normal hearing guinea pigs and one implanted with a silicone filament were fixed in paraformaldehyde (PFA), decalcified, dehydrated and cleared in Spalteholz solution. Using the tissue's autofluorescence, CLSM was performed at 100 fold magnification generating z-series stacks of about 20 slices of the modiolus. In 5 midmodiolar slices per cochlea the perimeters of the Rosenthal's Canal were surveyed, representative neuron diameters were measured and the neurons first counted manually and then software-assisted. For comparison, 8 normal hearing guinea pig cochleae were embedded in paraffin and examined similarly. The CLSM method has the advantage that the cochleae remain intact as an organ and keep their geometrical structure. Z-stack creation is nearly fully-automatic and frequently repeatable with various objectives and step sizes and without visible bleaching. The tissue shows minimal or no shrinking artefacts and damage typical of embedding and sectioning. As a result, the cells in the cleared cochleae reach an average diameter of 21 μm and a density of about 18 cells/10,000 μm(2) with no significant difference between the manual and the automatical counts. Subsequently we compared the CLSM data with those generated using the established method of paraffin slides, where the SGN reached a mean density of 9.5 cells/10,000 μm(2) and a mean soma diameter of 13.6 μm. We were able to prove that the semi-automatic CLSM method is a simple and effective technique for auditory neuron count. It provides a high grade of tissue preservation and the automatic stack-generation as well as the counter software reduces the effort considerably. In addition this visualisation technique offers the potential to detect the position and orientation of cochlear implants (CI) within the cochlea and tissue growing in the scala tympani around the CI and at the position of the cochleostomy due to the fact that the implant does not have to be removed to perform histology as in case of the paraffin method.
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Affiliation(s)
- Antonina Wrzeszcz
- Department of Otolaryngology, Hannover Medical School, Carl-Neuberg-Str. 1, 30625 Hannover, Germany.
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