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Kanzaki S, Toyoda M, Umezawa A, Ogawa K. Application of Mesenchymal Stem Cell Therapy and Inner Ear Regeneration for Hearing Loss: A Review. Int J Mol Sci 2020; 21:ijms21165764. [PMID: 32796705 PMCID: PMC7460950 DOI: 10.3390/ijms21165764] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2020] [Accepted: 08/07/2020] [Indexed: 02/08/2023] Open
Abstract
Inner and middle ear disorders are the leading cause of hearing loss, and are said to be among the greatest risk factors of dementia. The use of regenerative medicine for the treatment of inner ear disorders may offer a potential alternative to cochlear implants for hearing recovery. In this paper, we reviewed recent research and clinical applications in middle and inner ear regeneration and cell therapy. Recently, the mechanism of inner ear regeneration has gradually been elucidated. "Inner ear stem cells," which may be considered the precursors of various cells in the inner ear, have been discovered in the cochlea and vestibule. Research indicates that cells such as hair cells, neurons, and spiral ligaments may form promising targets for inner ear regenerative therapies by the transplantation of stem cells, including mesenchymal stem cells. In addition, it is necessary to develop tests for the clinical monitoring of cell transplantation. Real-time imaging techniques and hearing rehabilitation techniques are also being investigated, and cell therapy has found clinical application in cochlear implant techniques.
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Affiliation(s)
- Sho Kanzaki
- Department of Otolaryngology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan;
- Correspondence:
| | - Masashi Toyoda
- Research Team for Geriatric Medicine, Tokyo Metropolitan Institute of Gerontology, 35-2 Sakae-cho, Itabashi, Tokyo 173-0015, Japan;
| | - Akihiro Umezawa
- National Center for Child Health and Development, 2-10-1 Okura, Setagaya, Tokyo 157-8535, Japan;
| | - Kaoru Ogawa
- Department of Otolaryngology, Keio University School of Medicine, 35 Shinanomachi, Shinjuku, Tokyo 160-8582, Japan;
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MRI detection of endolymphatic hydrops in Meniere's disease in 8 minutes using MIIRMR and a 20-channel coil after targeted gadolinium delivery. World J Otorhinolaryngol Head Neck Surg 2020; 5:180-187. [PMID: 32083244 PMCID: PMC7015851 DOI: 10.1016/j.wjorl.2019.04.001] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/18/2019] [Revised: 04/06/2019] [Accepted: 04/10/2019] [Indexed: 11/21/2022] Open
Abstract
Background Endolymphatic hydrops (EH) become visible in vertigo patients, particularly in those with Meniere's disease (MD), in vivo using gadolinium-enhanced MRI. However, the image quality is not satisfying after intravenous injection of gadolinium chelate (GdC), and occasional failure in GdC uptake has been noticed after traditional intratympanic injection. In the present report, targeted delivery of GdC and using a cost-effective MRI system to obtain high quality images of EH in only 8 min will be introduced. Methods 39 MD patients were recruited in the study. First, 0.1 ml of 20-fold diluted gadolinium-diethylenetriamine acid (Gd-DTPA) was delivered onto the posterior upper part of the tympanic medial wall using a soft-tipped micro-irrigation catheter through an artificially perforated tympanic membrane. Inner ear MRI was performed 24 h after Gd-DTPA administration using a 3T MR machine and a 20-channel head/neck coil with an 8 min sequence of medium inversion time inversion recovery imaging with magnitude reconstruction (MIIRMR). The parameters were as follows: TR 16000 ms, TE 663 ms, inversion time 2700 ms, flip angle 180°, slices per slab 60. Results Efficient inner ear uptake of Gd-DTPA was detected 24 h after delivery and it created excellent contrast in the inner ear of all cases. High quality images demonstrating EH in the vestibule and cochlea were obtained. Conclusion Targeted delivery of minimum Gd-DTPA (0.1 ml, 20-fold dilution) onto the posterior upper portion of the tympanic medial wall and MRI with MIIRMR in a 3T machine and 20-channel head/neck coil are clinically practical to obtain high quality images displaying EH.
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Coutant T, Laniesse D, Sykes JM. Advances in Therapeutics and Delayed Drug Release. Vet Clin North Am Exot Anim Pract 2019; 22:501-520. [PMID: 31395328 DOI: 10.1016/j.cvex.2019.05.006] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Reducing the frequency of drug administration in the treatment of exotic pets is advantageous because it may decrease handling frequency and thus potential stress and injury risk for the animal, increase owner compliance with the prescribed treatment, and decrease need for general anesthesia in patients that cannot be handled safely. Increasing efficient drug plasma concentration using sustained-released delivery systems is an appealing solution. Potential candidates that could provide a promising solution have been investigated in exotic pets. In this article, the technologies that are the closest to being integrated in exotic pet medicine are reviewed: osmotic pumps, nanoparticles, and hydrogels.
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Affiliation(s)
- Thomas Coutant
- Service NAC, CHV Fregis, 43 Avenue Aristide Briand, Arcueil 94110, France.
| | - Delphine Laniesse
- Eläinsairaala Evidensia Tammisto Vantaa, Tammiston Kauppatie 29, Vantaa 01510, Finland
| | - John M Sykes
- Wildlife Conservation Society, Zoological Health Program, 2300 Southern Boulevard, Bronx, NY 10460, USA
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Hackelberg S, Tuck SJ, He L, Rastogi A, White C, Liu L, Prieskorn DM, Miller RJ, Chan C, Loomis BR, Corey JM, Miller JM, Duncan RK. Nanofibrous scaffolds for the guidance of stem cell-derived neurons for auditory nerve regeneration. PLoS One 2017; 12:e0180427. [PMID: 28672008 PMCID: PMC5495534 DOI: 10.1371/journal.pone.0180427] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2016] [Accepted: 06/15/2017] [Indexed: 01/13/2023] Open
Abstract
Impairment of spiral ganglion neurons (SGNs) of the auditory nerve is a major cause for hearing loss occurring independently or in addition to sensory hair cell damage. Unfortunately, mammalian SGNs lack the potential for autonomous regeneration. Stem cell based therapy is a promising approach for auditory nerve regeneration, but proper integration of exogenous cells into the auditory circuit remains a fundamental challenge. Here, we present novel nanofibrous scaffolds designed to guide the integration of human stem cell-derived neurons in the internal auditory meatus (IAM), the foramen allowing passage of the spiral ganglion to the auditory brainstem. Human embryonic stem cells (hESC) were differentiated into neural precursor cells (NPCs) and seeded onto aligned nanofiber mats. The NPCs terminally differentiated into glutamatergic neurons with high efficiency, and neurite projections aligned with nanofibers in vitro. Scaffolds were assembled by seeding GFP-labeled NPCs on nanofibers integrated in a polymer sheath. Biocompatibility and functionality of the NPC-seeded scaffolds were evaluated in vivo in deafened guinea pigs (Cavia porcellus). To this end, we established an ouabain-based deafening procedure that depleted an average 72% of SGNs from apex to base of the cochleae and caused profound hearing loss. Further, we developed a surgical procedure to implant seeded scaffolds directly into the guinea pig IAM. No evidence of an inflammatory response was observed, but post-surgery tissue repair appeared to be facilitated by infiltrating Schwann cells. While NPC survival was found to be poor, both subjects implanted with NPC-seeded and cell-free control scaffolds showed partial recovery of electrically-evoked auditory brainstem thresholds. Thus, while future studies must address cell survival, nanofibrous scaffolds pose a promising strategy for auditory nerve regeneration.
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Affiliation(s)
- Sandra Hackelberg
- Kresge Hearing Research Institute, Department of Otolaryngology-Head & Neck Surgery, University of Michigan, Ann Arbor, MI, United States of America
| | - Samuel J. Tuck
- Geriatrics Research, Education, and Clinical Center (GRECC), VA Ann Arbor Healthcare Center (VAAAHC), Ann Arbor, MI, United States of America
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
| | - Long He
- Kresge Hearing Research Institute, Department of Otolaryngology-Head & Neck Surgery, University of Michigan, Ann Arbor, MI, United States of America
- Departments of Otorhinolaryngology, Guangzhou First Peoples' Hospital and First Affiliated Hospital, School of Medicine, Jinan University, Guangdong, China
| | - Arjun Rastogi
- Geriatrics Research, Education, and Clinical Center (GRECC), VA Ann Arbor Healthcare Center (VAAAHC), Ann Arbor, MI, United States of America
| | - Christina White
- Geriatrics Research, Education, and Clinical Center (GRECC), VA Ann Arbor Healthcare Center (VAAAHC), Ann Arbor, MI, United States of America
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
| | - Liqian Liu
- Kresge Hearing Research Institute, Department of Otolaryngology-Head & Neck Surgery, University of Michigan, Ann Arbor, MI, United States of America
| | - Diane M. Prieskorn
- Kresge Hearing Research Institute, Department of Otolaryngology-Head & Neck Surgery, University of Michigan, Ann Arbor, MI, United States of America
| | - Ryan J. Miller
- Kresge Hearing Research Institute, Department of Otolaryngology-Head & Neck Surgery, University of Michigan, Ann Arbor, MI, United States of America
- Geriatrics Research, Education, and Clinical Center (GRECC), VA Ann Arbor Healthcare Center (VAAAHC), Ann Arbor, MI, United States of America
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
| | - Che Chan
- Geriatrics Research, Education, and Clinical Center (GRECC), VA Ann Arbor Healthcare Center (VAAAHC), Ann Arbor, MI, United States of America
- Department of Materials Science and Engineering, University of Michigan, Ann Arbor, MI, United States of America
| | - Benjamin R. Loomis
- Kresge Hearing Research Institute, Department of Otolaryngology-Head & Neck Surgery, University of Michigan, Ann Arbor, MI, United States of America
| | - Joseph M. Corey
- Geriatrics Research, Education, and Clinical Center (GRECC), VA Ann Arbor Healthcare Center (VAAAHC), Ann Arbor, MI, United States of America
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, MI, United States of America
- Department of Neurology, University of Michigan, Ann Arbor, MI, United States of America
| | - Josef M. Miller
- Kresge Hearing Research Institute, Department of Otolaryngology-Head & Neck Surgery, University of Michigan, Ann Arbor, MI, United States of America
| | - R. Keith Duncan
- Kresge Hearing Research Institute, Department of Otolaryngology-Head & Neck Surgery, University of Michigan, Ann Arbor, MI, United States of America
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Wang Y, Olson ES. Cochlear perfusion with a viscous fluid. Hear Res 2016; 337:1-11. [PMID: 27220484 DOI: 10.1016/j.heares.2016.05.007] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/12/2015] [Revised: 05/06/2016] [Accepted: 05/19/2016] [Indexed: 11/28/2022]
Abstract
The flow of viscous fluid in the cochlea induces shear forces, which could provide benefit in clinical practice, for example to guide cochlear implant insertion or produce static pressure to the cochlear partition or wall. From a research standpoint, studying the effects of a viscous fluid in the cochlea provides data for better understanding cochlear fluid mechanics. However, cochlear perfusion with a viscous fluid may damage the cochlea. In this work we studied the physiological and anatomical effects of perfusing the cochlea with a viscous fluid. Gerbil cochleae were perfused at a rate of 2.4 μL/min with artificial perilymph (AP) and sodium hyaluronate (Healon, HA) in four different concentrations (0.0625%, 0.125%, 0.25%, 0.5%). The different HA concentrations were applied either sequentially in the same cochlea or individually in different cochleae. The perfusion fluid entered from the round window and was withdrawn from basal scala vestibuli, in order to perfuse the entire perilymphatic space. Compound action potentials (CAP) were measured after each perfusion. After perfusion with increasing concentrations of HA in the order of increasing viscosity, the CAP thresholds generally increased. The threshold elevation after AP and 0.0625% HA perfusion was small or almost zero, and the 0.125% HA was a borderline case, while the higher concentrations significantly elevated CAP thresholds. Histology of the cochleae perfused with the 0.0625% HA showed an intact Reissner's membrane (RM), while in cochleae perfused with 0.125% and 0.25% HA RM was torn. Thus, the CAP threshold elevation was likely due to the broken RM, likely caused by the shear stress produced by the flow of the viscous fluid. Our results and analysis indicate that the cochlea can sustain, without a significant CAP threshold shift, up to a 1.5 Pa shear stress. Beside these finding, in the 0.125% and 0.25% HA perfusion cases, a temporary CAP threshold shift was observed, perhaps due to the presence and then clearance of viscous fluid within the cochlea, or to a temporary position shift of the Organ of Corti. After 0.5% HA perfusion, a short latency positive peak (P0) appeared in the CAP waveform. This P0 might be due to a change in the cochlea's traveling-wave pattern, or distortion in the cochlear microphonic.
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Affiliation(s)
- Yi Wang
- Department of Biomedical Engineering, Columbia University, New York, NY 10025, USA
| | - Elizabeth S Olson
- Department of Biomedical Engineering, Columbia University, New York, NY 10025, USA; Department of Otolaryngology-Head & Neck Surgery, Columbia University, New York, NY 10032, USA.
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Ross AM, Rahmani S, Prieskorn DM, Dishman AF, Miller JM, Lahann J, Altschuler RA. Persistence, distribution, and impact of distinctly segmented microparticles on cochlear health following in vivo infusion. J Biomed Mater Res A 2016; 104:1510-22. [PMID: 26841263 DOI: 10.1002/jbm.a.35675] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/12/2015] [Revised: 01/11/2016] [Accepted: 01/29/2016] [Indexed: 01/12/2023]
Abstract
Delivery of pharmaceuticals to the cochleae of patients with auditory dysfunction could potentially have many benefits from enhancing auditory nerve survival to protecting remaining sensory cells and their neuronal connections. Treatment would require platforms to enable drug delivery directly to the cochlea and increase the potential efficacy of intervention. Cochlear implant recipients are a specific patient subset that could benefit from local drug delivery as more candidates have residual hearing; and since residual hearing directly contributes to post-implantation hearing outcomes, it requires protection from implant insertion-induced trauma. This study assessed the feasibility of utilizing microparticles for drug delivery into cochlear fluids, testing persistence, distribution, biocompatibility, and drug release characteristics. To allow for delivery of multiple therapeutics, particles were composed of two distinct compartments; one containing polylactide-co-glycolide (PLGA), and one composed of acetal-modified dextran and PLGA. Following in vivo infusion, image analysis revealed microparticle persistence in the cochlea for at least 7 days post-infusion, primarily in the first and second turns. The majority of subjects maintained or had only slight elevation in auditory brainstem response thresholds at 7 days post-infusion compared to pre-infusion baselines. There was only minor to limited loss of cochlear hair cells and negligible immune response based on CD45+ immunolabling. When Piribedil-loaded microparticles were infused, Piribedil was detectable within the cochlear fluids at 7 days post-infusion. These results indicate that segmented microparticles are relatively inert, can persist, release their contents, and be functionally and biologically compatible with cochlear function and therefore are promising vehicles for cochlear drug delivery. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 104A: 1510-1522, 2016.
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Affiliation(s)
- Astin M Ross
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, 48109.,Kresge Hearing Research Institute, University of Michigan, Ann Arbor, 48109
| | - Sahar Rahmani
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, 48109.,Biointerfaces Institute, University of Michigan, Ann Arbor, 48109
| | - Diane M Prieskorn
- Kresge Hearing Research Institute, University of Michigan, Ann Arbor, 48109
| | - Acacia F Dishman
- Biointerfaces Institute, University of Michigan, Ann Arbor, 48109.,Department of Biophysics, University of Michigan, Ann Arbor, 48109
| | - Josef M Miller
- Kresge Hearing Research Institute, University of Michigan, Ann Arbor, 48109
| | - Joerg Lahann
- Department of Biomedical Engineering, University of Michigan, Ann Arbor, 48109.,Biointerfaces Institute, University of Michigan, Ann Arbor, 48109.,Department of Chemical Engineering, University of Michigan, Ann Arbor, 48109
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Ayoob AM, Borenstein JT. The role of intracochlear drug delivery devices in the management of inner ear disease. Expert Opin Drug Deliv 2014; 12:465-79. [PMID: 25347140 DOI: 10.1517/17425247.2015.974548] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023]
Abstract
INTRODUCTION Diseases of the inner ear include those of the auditory and vestibular systems, and frequently result in disabling hearing loss or vertigo. Despite a rapidly expanding pipeline of potential cochlear therapeutics, the inner ear remains a challenging organ for targeted drug delivery, and new technologies are required to deliver these therapies in a safe and efficacious manner. In addition to traditional approaches for direct inner ear drug delivery, novel microfluidics-based systems are under development, promising improved control over pharmacokinetics over longer periods of delivery, ultimately with application towards hair cell regeneration in humans. AREAS COVERED Advances in the development of intracochlear drug delivery systems are reviewed, including passive systems, active microfluidic technologies and cochlear prosthesis-mediated delivery. This article provides a description of novel delivery systems and their potential future clinical applications in treating inner ear disease. EXPERT OPINION Recent progresses in microfluidics and miniaturization technologies are enabling the development of wearable and ultimately implantable drug delivery microsystems. Progress in this field is being spurred by the convergence of advances in molecular biology, microfluidic flow control systems and models for drug transport in the inner ear. These advances will herald a new generation of devices, with near-term applications in preclinical models, and ultimately with human clinical use for a range of diseases of the inner ear.
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Ceschi P, Bohl A, Sternberg K, Neumeister A, Senz V, Schmitz K, Kietzmann M, Scheper V, Lenarz T, Stöver T, Paasche G. Biodegradable polymeric coatings on cochlear implant surfaces and their influence on spiral ganglion cell survival. J Biomed Mater Res B Appl Biomater 2014; 102:1255-67. [DOI: 10.1002/jbm.b.33110] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2013] [Revised: 11/08/2013] [Accepted: 01/04/2014] [Indexed: 12/31/2022]
Affiliation(s)
- P. Ceschi
- Hannover Medical School; Department of Otolaryngology; Hannover Germany
- School of Veterinary Medicine Hannover Foundation; Department of Pharmacology; Toxicology and Pharmacy Hannover Germany
| | - A. Bohl
- University of Rostock, Institute for Biomedical Engineering; Rostock Germany
| | - K. Sternberg
- University of Rostock, Institute for Biomedical Engineering; Rostock Germany
| | | | - V. Senz
- University of Rostock, Institute for Biomedical Engineering; Rostock Germany
| | - K.P. Schmitz
- University of Rostock, Institute for Biomedical Engineering; Rostock Germany
| | - M. Kietzmann
- School of Veterinary Medicine Hannover Foundation; Department of Pharmacology; Toxicology and Pharmacy Hannover Germany
| | - V. Scheper
- Hannover Medical School; Department of Otolaryngology; Hannover Germany
| | - T. Lenarz
- Hannover Medical School; Department of Otolaryngology; Hannover Germany
| | - T. Stöver
- Hannover Medical School; Department of Otolaryngology; Hannover Germany
- KGU; Department of Otolaryngology; Frankfurt Germany
| | - G. Paasche
- Hannover Medical School; Department of Otolaryngology; Hannover Germany
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van Loon MC, Ramekers D, Agterberg MJ, de Groot JC, Grolman W, Klis SF, Versnel H. Spiral ganglion cell morphology in guinea pigs after deafening and neurotrophic treatment. Hear Res 2013; 298:17-26. [DOI: 10.1016/j.heares.2013.01.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2012] [Revised: 12/21/2012] [Accepted: 01/17/2013] [Indexed: 12/17/2022]
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Abstract
Animal studies on inner ear development, repair and regeneration provide understanding of molecular pathways that can be harnessed for treating inner ear disease. Use of transgenic mouse technology, in particular, has contributed knowledge of genes that regulate development of hair cells and innervation, and of molecular players that can induce regeneration, but this technology is not applicable for human treatment, for practical and ethical reasons. Therefore other means for influencing gene expression in the inner ear are needed. We describe several gene vectors useful for inner ear gene therapy and the practical aspects of introducing these vectors into the ear. We then review the progress toward using gene transfer for therapies in both auditory and balance systems, and discuss the technological milestones needed to advance to clinical application of these methods.
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Affiliation(s)
- Hideto Fukui
- Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, 1150 West Medical Center Dr., Ann Arbor, MI 48109-5648, USA
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Zhang Y, Zhang W, Johnston AH, Newman TA, Pyykk I, Zou J. Comparison of the distribution pattern of PEG-b-PCL polymersomes delivered into the rat inner ear via different methods. Acta Otolaryngol 2011; 131:1249-56. [PMID: 21905960 DOI: 10.3109/00016489.2011.615066] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
CONCLUSION Cochleostomy is the most efficient approach in delivering PEG-b-PCL polymersomes (PMs) to the inner ear. PMs can be delivered to the vestibule by transtympanic injection or cochleostomy. OBJECTIVE To evaluate the efficiency of delivering PEG-b-PCL PMs into the inner ear using different approaches. METHODS The PEG-b-PCL PMs were administered either by sustained topical round window membrane (RWM) delivery using gelatin sponge pledgets in combination with an osmotic pump, transtympanic injection, or cochleostomy. The distribution of the PMs in the inner ear was observed by confocal microscopy using either whole mount specimens or cryosections. RESULTS Cochleostomy resulted in distribution of the PMs in the spiral ligament (SL), mesothelial cells beneath the organ of Corti, supporting cells in the organ of Corti, and spiral ganglion cells (SGCs). Transtympanic injection induced uptake of the PMs in the SL and mesothelial cells beneath the organ of Corti. Topical administration showed distribution of the PMs only in the SL. In the vestibulum, transtympanic injection and cochleostomy induced more distribution of the PMs than did topical RWM delivery (p < 0.05, Kruskal-Wallis test).
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Affiliation(s)
- Ya Zhang
- Department of Otolaryngology, University of Tampere, Medical school and University Hospital of Tampere, Finland
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12
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Li X, Mao XB, Hei RY, Zhang ZB, Wen LT, Zhang PZ, Qiu JH, Qiao L. Protective role of hydrogen sulfide against noise-induced cochlear damage: a chronic intracochlear infusion model. PLoS One 2011; 6:e26728. [PMID: 22046339 PMCID: PMC3202565 DOI: 10.1371/journal.pone.0026728] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2011] [Accepted: 10/02/2011] [Indexed: 12/26/2022] Open
Abstract
Background A reduction in cochlear blood flow plays an essential role in noise-induced hearing loss (NIHL). The timely regulation of cochlear perfusion determines the progression and prognosis of NIHL. Hydrogen sulfide (H2S) has attracted increasing interest as a vasodilator in cardiovascular systems. This study identified the role of H2S in cochlear blood flow regulation and noise protection. Methodology/Principal Findings The gene and protein expression of the H2S synthetase cystathionine-γ-lyase (CSE) in the rat cochlea was examined using immunofluorescence and real-time PCR. Cochlear CSE mRNA levels varied according to the duration of noise exposure. A chronic intracochlear infusion model was built and artificial perilymph (AP), NaHS or DL-propargylglycine (PPG) were locally administered. Local sodium hydrosulfide (NaHS) significantly increased cochlear perfusion post-noise exposure. Cochlear morphological damage and hearing loss were alleviated in the NaHS group as measured by conventional auditory brainstem response (ABR), cochlear scanning electron microscope (SEM) and outer hair cell (OHC) count. The highest percentage of OHC loss occurred in the PPG group. Conclusions/Significance Our results suggest that H2S plays an important role in the regulation of cochlear blood flow and the protection against noise. Further studies may identify a new preventive and therapeutic perspective on NIHL and other blood supply-related inner ear diseases.
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Affiliation(s)
- Xu Li
- Department of Otolaryngology-Head and Neck Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Xiao-Bo Mao
- Department of Otolaryngology-Head and Neck Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Ren-Yi Hei
- Department of Otolaryngology-Head and Neck Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | | | - Li-Ting Wen
- Department of Otolaryngology-Head and Neck Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Peng-Zhi Zhang
- Department of Otolaryngology-Head and Neck Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, China
| | - Jian-Hua Qiu
- Department of Otolaryngology-Head and Neck Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, China
- * E-mail: (J-HQ); (LQ)
| | - Li Qiao
- Department of Otolaryngology-Head and Neck Surgery, Xijing Hospital, Fourth Military Medical University, Xi'an, China
- * E-mail: (J-HQ); (LQ)
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Abstract
INTRODUCTION Advances in molecular biology and in the basic understanding of the mechanisms associated with sensorineural hearing loss and other diseases of the inner ear are paving the way towards new approaches for treatments for millions of patients. However, the cochlea is a particularly challenging target for drug therapy, and new technologies will be required to provide safe and efficacious delivery of these compounds. Emerging delivery systems based on microfluidic technologies are showing promise as a means for direct intracochlear delivery. Ultimately, these systems may serve as a means for extended delivery of regenerative compounds to restore hearing in patients suffering from a host of auditory diseases. AREAS COVERED Recent progress in the development of drug delivery systems capable of direct intracochlear delivery is reviewed, including passive systems such as osmotic pumps, active microfluidic devices and systems combined with currently available devices such as cochlear implants. The aim of this article is to provide a concise review of intracochlear drug delivery systems currently under development and ultimately capable of being combined with emerging therapeutic compounds for the treatment of inner ear diseases. EXPERT OPINION Safe and efficacious treatment of auditory diseases will require the development of microscale delivery devices, capable of extended operation and direct application to the inner ear. These advances will require miniaturization and integration of multiple functions, including drug storage, delivery, power management and sensing, ultimately enabling closed-loop control and timed-sequence delivery devices for treatment of these diseases.
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Affiliation(s)
- Jeffrey T Borenstein
- Biomedical Engineering Center, Draper Laboratory, Cambridge, MA 02139, United States.
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Stöver T, Lenarz T. Biomaterials in cochlear implants. GMS CURRENT TOPICS IN OTORHINOLARYNGOLOGY, HEAD AND NECK SURGERY 2011; 8:Doc10. [PMID: 22073103 PMCID: PMC3199815 DOI: 10.3205/cto000062] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
The cochlear implant (CI) represents, for almost 25 years now, the gold standard in the treatment of children born deaf and for postlingually deafened adults. These devices thus constitute the greatest success story in the field of ‘neurobionic’ prostheses. Their (now routine) fitting in adults, and especially in young children and even babies, places exacting demands on these implants, particularly with regard to the biocompatibility of a CI’s surface components. Furthermore, certain parts of the implant face considerable mechanical challenges, such as the need for the electrode array to be flexible and resistant to breakage, and for the implant casing to be able to withstand external forces. As these implants are in the immediate vicinity of the middle-ear mucosa and of the junction to the perilymph of the cochlea, the risk exists – at least in principle – that bacteria may spread along the electrode array into the cochlea. The wide-ranging requirements made of the CI in terms of biocompatibility and the electrode mechanism mean that there is still further scope – despite the fact that CIs are already technically highly sophisticated – for ongoing improvements to the properties of these implants and their constituent materials, thus enhancing the effectiveness of these devices. This paper will therefore discuss fundamental material aspects of CIs as well as the potential for their future development.
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Affiliation(s)
- Timo Stöver
- Department of Otolaryngology, Goethe University Frankfurt, Frankfurt a.M., Germany
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Pararas EEL, Chen Z, Fiering J, Mescher MJ, Kim ES, McKenna MJ, Kujawa SG, Borenstein JT, Sewell WF. Kinetics of reciprocating drug delivery to the inner ear. J Control Release 2011; 152:270-7. [PMID: 21385596 DOI: 10.1016/j.jconrel.2011.02.021] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2010] [Revised: 02/08/2011] [Accepted: 02/23/2011] [Indexed: 11/26/2022]
Abstract
Reciprocating drug delivery is a means of delivering soluble drugs directly to closed fluid spaces in the body via a single cannula without an accompanying fluid volume change. It is ideally suited for drug delivery into small, sensitive and unique fluid spaces such as the cochlea. We characterized the pharmacokinetics of reciprocating drug delivery to the scala tympani within the cochlea by measuring the effects of changes in flow parameters on the distribution of drug throughout the length of the cochlea. Distribution was assessed by monitoring the effects of DNQX, a reversible glutamate receptor blocker, delivered directly to the inner ear of guinea pigs using reciprocating flow profiles. We then modeled the effects of those parameters on distribution using both an iterative curve-fitting approach and a computational fluid dynamic model. Our findings are consistent with the hypothesis that reciprocating delivery distributes the drug into a volume in the base of the cochlea, and suggest that the primary determinant of distribution throughout more distal regions of the cochlea is diffusion. Increases in flow rate distributed the drug into a larger volume that extended more apically. Over short time courses (less than 2h), the apical extension, though small, significantly enhanced apically directed delivery of drug. Over longer time courses (>5h) or greater distances (>3mm), maintenance of drug concentration in the basal scala tympani may prove more advantageous for extending apical delivery than increases in flow rate. These observations demonstrate that this reciprocating technology is capable of providing controlled delivery kinetics to the closed fluid space in the cochlea, and may be suitable for other applications such as localized brain and retinal delivery.
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Round window perfusion dynamics: implications for intracochlear therapy. Curr Opin Otolaryngol Head Neck Surg 2011; 18:377-85. [PMID: 20808222 DOI: 10.1097/moo.0b013e32833d30f0] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
PURPOSE OF REVIEW The treatments for inner ear diseases are evolving as the systemic administration of medication is replaced by novel intratympanic and intracochlear drug delivery. The current review explores the background and recent developments in this field. RECENT FINDINGS Although still in various stages of clinical development, novel drug delivery techniques such as the Silverstein MicroWick, the round window microcatheter, biodegradable hydrogels, biopolymers, nanoparticles, newly designed cochlear implant arrays, osmotic mini/micro pumps, and reciprocating perfusion systems hold significant promise. Animal data suggest that sustained delivery systems have more reliable inner ear pharmacokinetics than both systemic administration and intratympanic injections. SUMMARY As research scientists advance technologies for treating inner ear diseases, drug delivery techniques must keep pace. Viable treatment options for sensorineural hearing loss, tinnitus, and vestibular disorders are on the horizon and may usher in a new golden age for otology.
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Farahmand Ghavi F, Mirzadeh H, Imani M, Jolly C, Farhadi M. Corticosteroid-releasing cochlear implant: a novel hybrid of biomaterial and drug delivery system. J Biomed Mater Res B Appl Biomater 2010; 94:388-398. [PMID: 20583307 DOI: 10.1002/jbm.b.31666] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
In this study, drug-eluting cochlear implant (CI) electrodes were prepared, and the amount of drug released was determined. Dexamethasone (DEX) (0.25-2% w/w, the weight percent of the final cured polymer) was used as a bioactive agent to suppress postsurgical inflammations upon mixing with a two-part nonrestricted pourable medical-grade silicone elastomer. Batch reproducibility analysis was performed on three consecutive batches. Drug release experiments were accomplished in normal saline medium, where DEX was analyzed via a validated HPLC method. The drug loading percentage and the device surface area were the most dominant parameters explored to monitor the drug release behavior from CI coatings. Total cumulative amount of DEX released from various loaded samples was in the order of 2 > 1 > 0.5 > 0.35 > 0.25% w/w, but the cumulative percentage of drug released showed a reverse order. The DEX dosages between 0.1 and 1 microg were released from samples of smallest to highest loadings during the initial 24 h, and dosages <1-5 microg were released from similar samples of various loadings at the first patency 2 weeks. The extent of crosslinking was only effective on release profile at lower drug loadings of 0.25% w/w relative to 0.5%. It was also found that release profile was not affected by postcuring. (c) 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2010.
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Affiliation(s)
- Farhid Farahmand Ghavi
- Department of Novel Drug Delivery Systems, Iran Polymer and Petrochemical Institute, 14965/115 Tehran, Iran
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Abstract
Artemin and its receptors are upregulated in the auditory nerve of deafened rats as a possible intrinsic protective mechanism against ototoxicity-related apoptosis. Consequently, we examined the effect of artemin on spiral ganglion neurons in vitro and in vivo. Spiral ganglion neurons were isolated from neonatal rats and cultured in serum-free medium supplemented with artemin and/or brain-derived neurotrophic factor (BDNF). In vitro, the survival rate of spiral ganglion neurons cultivated with artemin or BDNF was significantly improved compared with negative controls. In addition, artemin was delivered to the inner ear of deafened guinea pigs for 28 days. In-vivo artemin was as effective as BDNF in spiral ganglion neuron protection. Therefore, artemin promotes the survival of spiral ganglion neurons in vitro and in vivo.
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Abstract
Delivery of medications to the inner ear has been an area of considerable growth in both the research and clinical realms during the past several decades. Systemic delivery of medication destined for treatment of the inner ear is the foundation on which newer delivery techniques have been developed. Because of systemic side effects, investigators and clinicians have begun developing and using techniques to deliver therapeutic agents locally. Alongside the now commonplace use of intratympanic gentamicin for Meniere's disease and the emerging use of intratympanic steroids for sudden sensorineural hearing loss, novel technologies, such as hydrogels and nanoparticles, are being explored. At the horizon of inner ear drug-delivery techniques, intracochlear devices that leverage recent advances in microsystems technology are being developed to apply medications directly into the inner ear. Potential uses for such devices include neurotrophic factor and steroid delivery with cochlear implantation, RNA interference technologies, and stem-cell therapy. The historical, current, and future delivery techniques and uses of drug delivery for treatment of inner ear disease serve as the basis for this review.
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Garnham C, Reetz G, Jolly C, Miller J, Salt A, Beal F. Drug delivery to the cochlea after implantation: consideration of the risk factors. Cochlear Implants Int 2009; 6 Suppl 1:12-4. [PMID: 18792345 DOI: 10.1179/cim.2005.6.supplement-1.12] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
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Han Y, Zhong C, Hong L, Wang Y, Qiao L, Qiu J. Effect of c-myc on the ultrastructural structure of cochleae in guinea pigs with noise induced hearing loss. Biochem Biophys Res Commun 2009; 390:458-62. [PMID: 19785991 DOI: 10.1016/j.bbrc.2009.09.091] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2009] [Accepted: 09/23/2009] [Indexed: 11/16/2022]
Abstract
Noise over-stimulation may induce hair cells loss and hearing deficit. The c-myc oncogene is a major regulator for cell proliferation, growth, and apoptosis. However, the role of this gene in the mammalian cochlea is still unclear. The study was designed to firstly investigate its function under noise condition, from the aspect of cochlear ultrastructural changes. We had established the adenoviral vector of c-myc gene and delivered the adenovirus suspension into the scala tympani of guinea pigs 4 days before noise exposure. The empty adenoviral vectors were injected as control. Then, all subjects were exposed to 4-kHz octave-band noise at 110dB SPL for 8h/day, 3 days consecutively. Auditory thresholds were assessed by auditory brainstem response, prior to and 7 days following noise exposure. On the seventh days after noise exposure, the cochlear sensory epithelia surface was observed microscopically and the cochleae were taken to study the ultrastructural changes. The results indicated that auditory threshold shift after noise exposure was higher in the ears treated with Ad.EGFP than that treated with Ad.c-myc-EGFP. Stereocilia loss and the disarrangement of outer hair cells were observed, with greater changes found in the Ad.EGFP group. Also, the ultrastructure changes were severe in the Ad.EGFP group, but not obvious in the Ad.c-myc-EGFP group. Therefore, c-myc gene might play an unexpected role in hearing functional and morphological protection from acoustic trauma.
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Affiliation(s)
- Yu Han
- Department of Otolaryngology, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032 Shaanxi Province, China
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Scheper V, Wolf M, Scholl M, Kadlecova Z, Perrier T, Klok HA, Saulnier P, Lenarz T, Stöver T. Potential novel drug carriers for inner ear treatment: hyperbranched polylysine and lipid nanocapsules. Nanomedicine (Lond) 2009; 4:623-35. [DOI: 10.2217/nnm.09.41] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Aim: Treatment of sensorineural hearing loss could be advanced using novel drug carriers such as hyperbranched polylysine (HBPL) or lipid nanocapsules (LNCs). This study examined HBPL and LNCs for their cellular uptake and possible toxicity in vitro and in vivo as the first step in developing novel nanosized multifunctional carriers. Method: Having incubated HBPL and LNCs with fibroblasts, nanoparticle uptake and cell viability were determined by confocal laser scanning microscopy, fluorescence measurements and neutral red staining. In vivo, electrophysiology, confocal laser scanning microscopy and cytocochleograms were performed for nanoparticle detection and also toxicity studies after intracochlear application. Results: Both nanoparticles were detectable in the fibroblasts’ cytoplasm without causing cytotoxic effects. After in vivo application they were visualized in cochlear cells, which did not lead to a change in hearing threshold or loss of hair cells. Biocompatibility and traceability were demonstrated for HBPL and LNCs. Thus, they comply with the basic requirements for drug carriers for potential application in the inner ear.
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Affiliation(s)
- Verena Scheper
- Department of Otolaryngology, Medical University Hannover, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Melanie Wolf
- Department of Otolaryngology, Medical University Hannover, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Markus Scholl
- École Polytechnique Fédérale de Lausanne, Institut des Matériaux, Laboratoire des Polymères, MXD 135 (Bâtiment MX-D), Switzerland
| | - Zuzana Kadlecova
- École Polytechnique Fédérale de Lausanne, Institut des Matériaux, Laboratoire des Polymères, MXD 135 (Bâtiment MX-D), Switzerland
| | - Thomas Perrier
- Université Angers – INSERM U646, Laboratoires Annuaires Ingénierie de la Vectorisation Particulaire, France
| | - Harm-Anton Klok
- École Polytechnique Fédérale de Lausanne, Institut des Matériaux, Laboratoire des Polymères, MXD 135 (Bâtiment MX-D), Switzerland
| | - Patrick Saulnier
- Université Angers – INSERM U646, Laboratoires Annuaires Ingénierie de la Vectorisation Particulaire, France
| | - Thomas Lenarz
- Department of Otolaryngology, Medical University Hannover, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
| | - Timo Stöver
- Department of Otolaryngology, Medical University Hannover, Carl-Neuberg-Str. 1, 30625 Hannover, Germany
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Glutamatergic neuronal differentiation of mouse embryonic stem cells after transient expression of neurogenin 1 and treatment with BDNF and GDNF: in vitro and in vivo studies. J Neurosci 2009; 28:12622-31. [PMID: 19036956 DOI: 10.1523/jneurosci.0563-08.2008] [Citation(s) in RCA: 98] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
Differentiation of the pluripotent neuroepithelium into neurons and glia is accomplished by the interaction of growth factors and cell-type restricted transcription factors. One approach to obtaining a particular neuronal phenotype is by recapitulating the expression of these factors in embryonic stem (ES) cells. Toward the eventual goal of auditory nerve replacement, the aim of the current investigation was to generate auditory nerve-like glutamatergic neurons from ES cells. Transient expression of Neurog1 promoted widespread neuronal differentiation in vitro; when supplemented with brain-derived neurotrophic factor (BDNF) and glial cell line-derived neurotrophic factor (GDNF), 75% of ES cell-derived neurons attained a glutamatergic phenotype after 5 d in vitro. Mouse ES cells were also placed into deafened guinea pig cochleae and Neurog1 expression was induced for 48 h followed by 26 d of BDNF/GDNF infusion. In vivo differentiation resulted in 50-75% of ES cells bearing markers of early neurons, and a majority of these cells had a glutamatergic phenotype. This is the first study to report a high percentage of ES cell differentiation into a glutamatergic phenotype and sets the stage for cell replacement of auditory nerve.
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Abstract
PURPOSE OF REVIEW Treatment of auditory and vestibular dysfunction has become increasingly dependent on inner ear drug delivery. Recent advances in molecular therapy and nanotechnology have pushed development of alternate delivery methodologies involving both transtympanic and direct intracochlear infusions. This review examines recent developments in the field relevant to both clinical and animal research environments. RECENT FINDINGS Transtympanic delivery of gentamicin and corticosteroids for the treatment of Meniere's disease and sudden sensorineural hearing loss continues to be clinically relevant, with understanding of pharmacokinetics becoming more closely studied. Stabilizing matrices placed on the round window membrane for sustained passive delivery of compounds offer more controlled dosing profiles than transtympanic injections. Nanoparticles are capable of traversing the round window membrane and cochlear membranous partitions, and may become useful gene delivery platforms. Cochlear and vestibular hair cell regeneration has been demonstrated by vector delivery to the inner ear, offering promise for future advanced therapies. SUMMARY Optimal methods of inner ear drug delivery will depend on toxicity, therapeutic dose range, and characteristics of the agent to be delivered. Advanced therapy development will likely require direct intracochlear delivery with detailed understanding of associated pharmacokinetics.
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Swan EEL, Mescher MJ, Sewell WF, Tao SL, Borenstein JT. Inner ear drug delivery for auditory applications. Adv Drug Deliv Rev 2008; 60:1583-99. [PMID: 18848590 PMCID: PMC2657604 DOI: 10.1016/j.addr.2008.08.001] [Citation(s) in RCA: 144] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2008] [Accepted: 08/21/2008] [Indexed: 02/07/2023]
Abstract
Many inner ear disorders cannot be adequately treated by systemic drug delivery. A blood-cochlear barrier exists, similar physiologically to the blood-brain barrier, which limits the concentration and size of molecules able to leave the circulation and gain access to the cells of the inner ear. However, research in novel therapeutics and delivery systems has led to significant progress in the development of local methods of drug delivery to the inner ear. Intratympanic approaches, which deliver therapeutics to the middle ear, rely on permeation through tissue for access to the structures of the inner ear, whereas intracochlear methods are able to directly insert drugs into the inner ear. Innovative drug delivery systems to treat various inner ear ailments such as ototoxicity, sudden sensorineural hearing loss, autoimmune inner ear disease, and for preserving neurons and regenerating sensory cells are being explored.
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Affiliation(s)
- Erin E Leary Swan
- Charles Stark Draper Laboratory, 555 Technology Square, Cambridge, MA 02139, USA.
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26
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Morphological changes in spiral ganglion cells after intracochlear application of brain-derived neurotrophic factor in deafened guinea pigs. Hear Res 2008; 244:25-34. [PMID: 18692557 DOI: 10.1016/j.heares.2008.07.004] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/22/2007] [Revised: 07/01/2008] [Accepted: 07/02/2008] [Indexed: 01/23/2023]
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Altschuler RA, O'Shea KS, Miller JM. Stem cell transplantation for auditory nerve replacement. Hear Res 2008; 242:110-6. [PMID: 18585449 DOI: 10.1016/j.heares.2008.06.004] [Citation(s) in RCA: 45] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/01/2007] [Revised: 06/01/2008] [Accepted: 06/03/2008] [Indexed: 01/03/2023]
Abstract
The successful function of cochlear prostheses depends on activation of auditory nerve. The survival of auditory nerve neurons, however, can vary widely in candidates for cochlear implants and influence implant efficacy. Stem cells offer the potential for improving the function of cochlear prostheses and increasing the candidate pool by replacing lost auditory nerve. The first phase of studies for stem cell replacement of auditory nerve has examined the in vitro survival and differentiation as well as in vivo differentiation and survival of exogenous embryonic and tissue stem cells placed into scala tympani and/or modiolus. These studies are reviewed and new results on in vivo placement of B-5 mouse embryonic stem cells into scala tympani of the guinea pig cochleae with differentiation into a glutamatergic neuronal phenotype are presented. Research on the integration and connections of stem cell derived neurons in the cochlea is described. Finally, an alternative approach is considered, based on the use of endogenous progenitors rather than exogenous stem cells, with a review of promising findings that have identified stem cell-like progenitors in cochlear and vestibular tissues to provide the potential for auditory nerve replacement.
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Affiliation(s)
- Richard A Altschuler
- Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, 1150W. Medical Center Drive, Ann Arbor, MI 48109-5616, United States.
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Hendricks JL, Chikar JA, Crumling MA, Raphael Y, Martin DC. Localized cell and drug delivery for auditory prostheses. Hear Res 2008; 242:117-31. [PMID: 18573323 DOI: 10.1016/j.heares.2008.06.003] [Citation(s) in RCA: 51] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/19/2007] [Revised: 05/09/2008] [Accepted: 06/02/2008] [Indexed: 12/20/2022]
Abstract
Localized cell and drug delivery to the cochlea and central auditory pathway can improve the safety and performance of implanted auditory prostheses (APs). While generally successful, these devices have a number of limitations and adverse effects including limited tonal and dynamic ranges, channel interactions, unwanted stimulation of non-auditory nerves, immune rejection, and infections including meningitis. Many of these limitations are associated with the tissue reactions to implanted auditory prosthetic devices and the gradual degeneration of the auditory system following deafness. Strategies to reduce the insertion trauma, degeneration of target neurons, fibrous and bony tissue encapsulation, and immune activation can improve the viability of tissue required for AP function as well as improve the resolution of stimulation for reduced channel interaction and improved place-pitch and level discrimination. Many pharmaceutical compounds have been identified that promote the viability of auditory tissue and prevent inflammation and infection. Cell delivery and gene therapy have provided promising results for treating hearing loss and reversing degeneration. Currently, many clinical and experimental methods can produce extremely localized and sustained drug delivery to address AP limitations. These methods provide better control over drug concentrations while eliminating the adverse effects of systemic delivery. Many of these drug delivery techniques can be integrated into modern auditory prosthetic devices to optimize the tissue response to the implanted device and reduce the risk of infection or rejection. Together, these methods and pharmaceutical agents can be used to optimize the tissue-device interface for improved AP safety and effectiveness.
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Affiliation(s)
- Jeffrey L Hendricks
- Department of Biomedical Engineering, The University of Michigan, 1107 Gerstacker Building, 2200 Bonisteel Boulevard, Ann Arbor, MI 48109-2099, USA.
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Yang J, Wu H, Zhang P, Hou DM, Chen J, Zhang SG. The pharmacokinetic profiles of dexamethasone and methylprednisolone concentration in perilymph and plasma following systemic and local administration. Acta Otolaryngol 2008; 128:496-504. [PMID: 17917839 DOI: 10.1080/00016480701558906] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
CONCLUSION Both methylprednisolone (MTH) and dexamethasone (DEX) could successfully and effectively penetrate the round window membrane (RWM) into perilymph. RWM topical application and otocyst infusion with MTH and DEX result in high perilymph drug concentrations and low plasma levels. An intratympanic administration schedule for DEX or MTH could be carried out twice daily. OBJECTIVE To explore the pharmacokinetics of DEX and MTH in the inner ear fluids and plasma following systemic and local administration. MATERIALS AND METHODS Three routes of administration of steroids were used in guinea pigs: intracardial injection, otocyst infusion and RWM topical application by granule gelfoam soaked with steroids. Samples of blood or perilymph of the scala tympani were collected at 1-6 h after administration. High-performance liquid chromatography was used to assay concentrations of steroids. RESULTS Both the topical application and infusion administration resulted in a significantly higher concentration of steroids in perilymph than intracardial injection. The level of steroids in the perilymph reached a peak at 1-2 h after dosing, and this was maintained at a relatively high level for several hours. The intracardial injection with steroids yielded very low perilymph levels at all sampling times after administration.
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30
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Johnson DG, Zhu XX, Frisina RD, Borkholder DA. Micro-molded cannulae for intracochlear infusions in small rodents. ACTA ACUST UNITED AC 2008; 2007:6617-20. [PMID: 18003542 DOI: 10.1109/iembs.2007.4353876] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
Abstract
The design, fabrication, and testing of micro-cannulae with integrated insertion stops is presented. The micro-cannulae were engineered through the use of a silicon micro-mold fabricated via bulk-silicon micro-machining techniques. The use of microelectronic fabrication techniques allows precise control of three critical parameters, insertion depth, interface contact area, and tubing out of round. Worst case variations were found to be 5microm for insertion depth, 502microm(2) for interface contact area, and 7% for tip out of round. Histological evaluation revealed the cannula to be located correctly within the basal portion of scala tympani.
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Affiliation(s)
- Dean G Johnson
- Rochester Institute of Technology, Rochester, NY, 14623 USA.
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Glueckert R, Bitsche M, Miller JM, Zhu Y, Prieskorn DM, Altschuler RA, Schrott-Fischer A. Deafferentiation-associated changes in afferent and efferent processes in the guinea pig cochlea and afferent regeneration with chronic intrascalar brain-derived neurotrophic factor and acidic fibroblast growth factor. J Comp Neurol 2008; 507:1602-21. [DOI: 10.1002/cne.21619] [Citation(s) in RCA: 117] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
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Miller JM, Le Prell CG, Prieskorn DM, Wys NL, Altschuler RA. Delayed neurotrophin treatment following deafness rescues spiral ganglion cells from death and promotes regrowth of auditory nerve peripheral processes: effects of brain-derived neurotrophic factor and fibroblast growth factor. J Neurosci Res 2007; 85:1959-69. [PMID: 17492794 DOI: 10.1002/jnr.21320] [Citation(s) in RCA: 85] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
The extent to which neurotrophic factors are able to not only rescue the auditory nerve from deafferentation-induced degeneration but also promote process regrowth is of basic and clinical interest, as regrowth may enhance the therapeutic efficacy of cochlear prostheses. The use of neurotrophic factors is also relevant to interventions to promote regrowth and repair at other sites of nerve trauma. Therefore, auditory nerve survival and peripheral process regrowth were assessed in the guinea pig cochlea following chronic infusion of BDNF + FGF(1) into scala tympani, with treatment initiated 4 days, 3 weeks, or 6 weeks after deafferentation from deafening. Survival of auditory nerve somata (spiral ganglion neurons) was assessed from midmodiolar sections. Peripheral process regrowth was assessed using pan-Trk immunostaining to selectively label afferent fibers. Significantly enhanced survival was seen in each of the treatment groups compared to controls receiving artificial perilymph. A large increase in peripheral processes was found with BDNF + FGF(1) treatment after a 3-week delay compared to the artificial perilymph controls and a smaller enhancement after a 6-week delay. Neurotrophic factor treatment therefore has the potential to improve the benefits of cochlear implants by maintaining a larger excitable population of neurons and inducing neural regrowth.
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Affiliation(s)
- Josef M Miller
- Kresge Hearing Research Institute, University of Michigan, Ann Arbor, Michigan 48109-0506, USA.
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Matsuoka AJ, Kondo T, Miyamoto RT, Hashino E. Enhanced Survival of Bone???Marrow-Derived Pluripotent Stem Cells in an Animal Model of Auditory Neuropathy. Laryngoscope 2007; 117:1629-35. [PMID: 17632425 DOI: 10.1097/mlg.0b013e31806bf282] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
OBJECTIVE The loss of spiral ganglion neurons (SGNs) is one of the major causes of profound sensorineural hearing loss (SNHL). Stem cell replacement therapy, which is still in its infancy, has the potential to treat or cure those who suffer from an array of illnesses and degenerative neurologic disorders, including sensorineural deafness (SNHL). Little is known about the potentials of mesenchymal stem cells (MSCs) and their ability to take on properties of SGNs. The two main purposes of this study were to evaluate the survival of mouse MSCs transplanted into normal and ouabain-treated gerbil cochleae and to determine the migratory patterns of MSCs with two differing injection methods. SUBJECTS Thirty-two Mongolian gerbils, 3 to 4 months old, were used as recipients, and four 6-week-old TgN(ACTbEGFP) mice that ubiquitously express green fluorescent protein (GFP) were used as donors. DESIGN The animals were deafened by ouabain, which damaged SGNs while leaving hair cell systems intact. After 4 weeks of recovery, the animals received an intraperilymphatic transplantation of 1.0x10(6) GFP-positive undifferentiated MSCs via two different injection methods: scala tympani injection and modiolar injection. Seven days after the transplantation, the survival of MSCs was evaluated by microscopic examination of frozen sections cut through the cochleae of the recipient animals. The number of profiles was counted on the five most central modiolar sections. One-way analyses of variance (ANOVA) were used to determine any significantdifferences among mean profile counts across the experimental conditions. RESULTS Our findings indicated that undifferentiated MSCs were able to survive in the modiolus both in the control and the ouabain-treated cochleae. The average number of profiles found in the modiolus was greater in the ouabain-treated cochleae than in the control cochleae. This difference was statistically significant (P<.01) as determined using a one-way ANOVA and an ad hoc Tukey-Kramer's test. With the scala tympani injection, there were no profiles found in the modiolus either in the control or ouabain-treated cochleae. This finding may indicate that donor MSCs need to be directly injected into the modiolus to replace injured SGNs. Finally, there was no evidence of hyperacute rejection in any of the gerbils despite the use of xenotransplantation. CONCLUSIONS These findings may have important clinical implications as a means of delivering MSCs in the cochlea for stem-cell replacement therapy. Survival of transplanted MSCs into the modiolus of the cochlea may result in regeneration of damaged SGNs.
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Affiliation(s)
- Akihiro J Matsuoka
- Department of Otolaryngology-Head and Neck Surgery, Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, Indiana 46202, USA.
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Stöver T, Paasche G, Lenarz T, Ripken T, Breitenfeld P, Lubatschowski H, Fabian T. Development of a drug delivery device: using the femtosecond laser to modify cochlear implant electrodes. Cochlear Implants Int 2007; 8:38-52. [PMID: 17479965 DOI: 10.1179/cim.2007.8.1.38] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/31/2022]
Abstract
Animal experiments suggest that pharmacological intervention could possibly enhance cochlear implant performance. One of the key aspects is therefore a drug delivery device for the human inner ear. The objective of this study was to investigate the possibility of using the femtosecond laser for modifying a cochlear implant electrode for the purpose of drug delivery to the cochlea. Using silicone sheets, the best parameters for creating defined channels at calculated diameters were investigated using a femtosecond laser. The results were transferred to a cochlear implant electrode array (Nucleus Contour). The capability of delivering substances through the drilled openings was tested in vitro. By variation of the output of the laser, spot distance, repetition rate, number of cycles and introducing several focus planes, it was possible to drill holes with nearly vertical walls in the silicone sheets. Transferring these data to the cochlear implant electrode resulted in prototypes for drug delivery with various openings along the array. The use of the femtosecond laser allows rapid modification and adaptation of designs to experimental prototypes of cochlear implant electrodes for the purpose of drug delivery to the inner ear.
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Affiliation(s)
- T Stöver
- Department of Otolaryngology, Medical University of Hannover, Germany.
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Maeda Y, Fukushima K, Kawasaki A, Nishizaki K, Smith RJH. Cochlear expression of a dominant-negative GJB2R75W construct delivered through the round window membrane in mice. Neurosci Res 2007; 58:250-4. [PMID: 17462767 DOI: 10.1016/j.neures.2007.03.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/26/2007] [Revised: 03/08/2007] [Accepted: 03/15/2007] [Indexed: 10/23/2022]
Abstract
Development of a gene-delivery method to the inner ear is an essential step for studies of hearing function and gene therapy. Application of liposomes or adenoviral vectors onto the intact round window membrane (RWM) offers the possibility of atraumatic exogenous gene transfer. GJB2 encodes the gap junction protein Connexin26, which plays a crucial role in potassium recycling in the inner ear. The R75W allele of GJB is a well-characterized mutation that causes deafness at the DFNA3 through a dominant-negative mechanism of action. In this study, a plasmid vector, pGJB2(R75W)-eGFP, was lipocomplexed with N-[1-(2,3-Dioleoloxy)propyl]N,N,N-trimethylammonium methylsulfate: cholesterol and applied onto mouse RWM. At 3 days (3d) post-treatment, immunohistochemistry demonstrated GJB2(R75W)-eGFP transgene expression in the cochlea in: inner and outer pillar cells, outer hair cells, Claudius cells and, in the spiral limbus and ligament. Significant hearing loss was detected by auditory brainstem response testing after 1, 2 and 3d post-treatment; hearing levels returned to control levels at 5d post-treatment. These data confirm that GJB2(R75W) induces functional impairment in the mature cochlea through a dominant negative effect, and importantly, that RWM application of exogenous genes is a feasible method to test their impact on hearing.
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Affiliation(s)
- Yukihide Maeda
- Department of Otolaryngology-Head and Neck Surgery, Okayama University Graduate School of Medicine, Dentistry and Pharmaceutical science, Okayama 700-8558, Japan
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Furukawa M, Ebmeyer J, Pak K, Austin DA, Melhus A, Webster NJG, Ryan AF. Jun N-terminal protein kinase enhances middle ear mucosal proliferation during bacterial otitis media. Infect Immun 2007; 75:2562-71. [PMID: 17325051 PMCID: PMC1865762 DOI: 10.1128/iai.01656-06] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Mucosal hyperplasia is a characteristic component of otitis media. The present study investigated the participation of signaling via the Jun N-terminal protein kinase (JNK) mitogen-activated protein kinase in middle ear mucosal hyperplasia in animal models of bacterial otitis media. Otitis media was induced by the inoculation of nontypeable Haemophilus influenzae into the middle ear cavity. Western blotting revealed that phosphorylation of JNK isoforms in the middle ear mucosa preceded but paralleled mucosal hyperplasia in this in vivo rat model. Nuclear JNK phosphorylation was observed in many cells of both the mucosal epithelium and stroma by immunohistochemistry. In an in vitro model of primary rat middle ear mucosal explants, bacterially induced mucosal growth was blocked by the Rac/Cdc42 inhibitor Clostridium difficile toxin B, the mixed-lineage kinase inhibitor CEP11004, and the JNK inhibitor SP600125. Finally, the JNK inhibitor SP600125 significantly inhibited mucosal hyperplasia during in vivo bacterial otitis media in guinea pigs. Inhibition of JNK in vivo resulted in a diminished proliferative response, as shown by a local decrease in proliferating cell nuclear antigen protein expression by immunohistochemistry. We conclude that activation of JNK is a critical pathway for bacterially induced mucosal hyperplasia during otitis media, influencing tissue proliferation.
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Affiliation(s)
- Masayuki Furukawa
- Department of Surgery, UCSD School of Medicine, Fir Bldg., Rm. 106, 9500 Gilman Dr. #0666, La Jolla, CA 92037, USA
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Kanzaki S, Shiotani A, Inoue M, Hasegawa M, Ogawa K. Sendai Virus Vector-Mediated Transgene Expression in the Cochlea in vivo. ACTA ACUST UNITED AC 2007; 12:119-26. [PMID: 17264475 DOI: 10.1159/000097798] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2005] [Accepted: 09/15/2006] [Indexed: 11/19/2022]
Abstract
We injected a recombinant Sendai virus (SeV) vector into the guinea pig cochlea using two different approaches--the scala media and scala tympani--and investigated which cell types took up the vector. The hearing threshold shift and distribution of transfected cells in animals using the scala media approach were different compared to those using the scala tympani approach. SeV can transfect very different types of cells, including stria vascularis, spiral ganglion neurons, and sensory epithelia of the organ of Corti, and fibrocytes of the scala tympani. Because SeV vectors can potentially deliver stimuli to the cochlea to induce hair cell regeneration, it may be a powerful tool for repairing the organ of Corti.
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Affiliation(s)
- Sho Kanzaki
- Department of Otolaryngology, Keio University, Tokyo, Japan.
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Hochmair I, Nopp P, Jolly C, Schmidt M, Schösser H, Garnham C, Anderson I. MED-EL Cochlear implants: state of the art and a glimpse into the future. Trends Amplif 2006; 10:201-19. [PMID: 17172548 PMCID: PMC4111377 DOI: 10.1177/1084713806296720] [Citation(s) in RCA: 99] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
Cochlear implantation is an accepted treatment method for adults and children with severe to profound hearing loss. Confidence in technology has led to changes in individuals who can receive a cochlear implant and changes in expected benefit with a cochlear implant. This article describes the research and development activities at MED-EL, which make possible the implementation of new speech-coding strategies as well as the application of acoustic and electric stimulation via a combined speech processor in MED-EL devices. Research on benefits from bilateral cochlear implantation and electric-acoustic stimulation are also reviewed. Finally, the potential of drug delivery systems is considered as a way to improve cochlear implant outcomes, and results from preliminary evaluations of a hybrid cochlear implant system with drug delivery capabilities are reported.
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Le Prell CG, Kawamoto K, Raphael Y, Dolan DF. Electromotile hearing: acoustic tones mask psychophysical response to high-frequency electrical stimulation of intact guinea pig cochleae. THE JOURNAL OF THE ACOUSTICAL SOCIETY OF AMERICA 2006; 120:3889-900. [PMID: 17225416 PMCID: PMC3132799 DOI: 10.1121/1.2359238] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
When sinusoidal electric stimulation is applied to the intact cochlea, a frequency-specific acoustic emission can be recorded in the ear canal. Acoustic emissions are produced by basilar membrane motion, and have been used to suggest a corresponding acoustic sensation termed "electromotile hearing." Electromotile hearing has been specifically attributed to electric stimulation of outer hair cells in the intact organ of Corti. To determine the nature of the auditory perception produced by electric stimulation of a cochlea with intact outer hair cells, guinea pigs were tested in a psychophysical task. First, subjects were trained to report detection of sinusoidal acoustic stimuli and dynamic range was assessed using response latency. Subjects were then implanted with a ball electrode placed into scala tympani. Following the surgical implant procedure, subjects were transferred to a task in which acoustic signals were replaced by sinusoidal electric stimulation, and dynamic range was assessed again. Finally, the ability of acoustic pure-tone stimuli to mask the detection of the electric signals was assessed. Based on the masking effects, it is concluded that sinusoidal electric stimulation of the intact cochlea results in perception of a tonal (rather than a broadband or noisy) sound at a frequency of 8 kHz or above.
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Affiliation(s)
- Colleen G Le Prell
- Kresge Hearing Research Institute, 1301 East Ann Street, Ann Arbor, Michigan 48109-0506, USA.
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Matsuoka AJ, Kondo T, Miyamoto RT, Hashino E. In vivo and in vitro characterization of bone marrow-derived stem cells in the cochlea. Laryngoscope 2006; 116:1363-7. [PMID: 16885736 DOI: 10.1097/01.mlg.0000225986.18790.75] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
OBJECTIVES/HYPOTHESIS Stem cell replacement therapy has the potential to treat or cure an array of degenerative neurologic disorders, including sensorineural deafness. However, little is known about the potential for marrow-derived stem cells (MSCs) to take on properties of spiral ganglion neurons. The main purpose of this prospective animal study was to evaluate the survival of MSCs transplanted into the gerbil cochlea. METHODS Eight 3- to 4-month-old Mongolian gerbils were used as recipients. The animals received an intraperilymphatic transplantation of 100,000 green fluorescent protein (GFP)-positive MSCs with scala tympani injection and modiolar injection. Seven days after transplantation, MSC survival was evaluated by microscopic examination of frozen sections cut through the cochleae of the recipient animals. RESULTS MSCs isolated from the TgN (ACTbEGFP) mouse line used in this study exhibited bright green florescence after five to seven passages in vitro. Seven days after postoperatively, most transplanted MSCs were found in the scala tympani and scala vestibule and only a small number located in the scala media in animals that received both forms of injection. There were no GFP-positive MSCs in the modiolus in animals with scala tympani injection. In contrast, the mean profile count in animals with modiolar injection was 28, which was the highest in all regions. Although MSCs have the potential to migrate, the anatomic barrier between the perilymphatic space and the modiolus might account for the absence of GFP-positive MSCs in this region. CONCLUSION These findings may have important clinical implications as a means of delivering MSCs in the cochlea for cell replacement therapy.
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Affiliation(s)
- Akihiro J Matsuoka
- Department of Otolaryngology-Head and Neck Surgery, Stark Neurosciences Research Institute, Indiana University School of Medicine, 699 West Drive, Indianapolis, IN 46202, USA.
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Abstract
OBJECTIVE To determine if exogenous neurotrophins can prevent spiral ganglion neuron degeneration in the rat cochlea. BACKGROUND The loss of hair cells resulting in sensorineural hearing loss also leads to the secondary degeneration of spiral ganglion neurons. The effectiveness of cochlear implantation in patients with profound sensorineural hearing loss relies in part on the survival of spiral ganglion neurons; therefore, any therapy that can prevent or halt the loss of these neurons would be of potential clinical benefit. Previous research has shown that intracochlear infusion with neurotrophins can provide trophic support to SGNs in deafened guinea pigs. Whether this effect is seen in other species remains to be determined. METHODS After documenting the rate of spiral ganglion neuron degeneration after ototoxic deafening, we investigated the trophic effects of exogenous brain-derived neurotrophic factor (BDNF) on rat spiral ganglion neurons. The left cochleae of profoundly deafened rats were implanted with a drug delivery system connected to a mini-osmotic pump. BDNF or artificial perilymph was infused for 28 days; then the cochleae were prepared for histological study. RESULTS Treatment with BDNF led to a statistically significant increase in spiral ganglion neuron density and a highly significant increase in spiral ganglion neuron soma area compared with artificial perilymph-treated and untreated deafened cochleae. CONCLUSION The study has demonstrated the trophic advantage of exogenous BDNF in the mature rat cochlea and provides confidence that spiral ganglion neuron rescue after sensorineural hearing loss with exogenous BDNF may have clinical application.
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Affiliation(s)
- Sarah L McGuinness
- Department of Otolaryngology, University of Melbourne, East Melbourne, Victoria, Australia
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Zhou J, Balaban C, Durrant JD. Effect of intracochlear perfusion of vanilloids on cochlear neural activity in the guinea pig. Hear Res 2006; 218:43-9. [PMID: 16781098 DOI: 10.1016/j.heares.2006.02.013] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/11/2005] [Revised: 01/31/2006] [Accepted: 02/21/2006] [Indexed: 11/17/2022]
Abstract
Recent findings show that the vanilloid receptor subtype 1 (TRPV1) is expressed by cochlear outer hair cells and spiral ganglion cells, and that its expression is up-regulated in ganglion cells after aminoglycoside treatment. This study tested the hypothesis that agents that act on TRPV1 receptors affect the spectrum of ensemble background activity (EBA). Consecutive intracochlear perfusions of the TRPV1 agonist, capsaicin (CAP 0.1, 1, and 10 parts per million), as well as its antagonist capsazepine (CZP), were used to test effects of TRPV1 activation on EBA recorded from the cochlear base. Perfusion with CAP alone produced a dose-dependent increase of the 900-Hz peak ratio (power normalized re the overall spectrum) of the EBA. The CAP effect was attenuated during concurrent perfusion with CZP. These findings are consistent with the hypothesis that TRPV1 activation increases background activity of spiral ganglion cells and support a role of TRPV1 in gating spontaneous and evoked auditory nerve excitability.
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Affiliation(s)
- Jianxun Zhou
- Department of Communication Science and Disorders, University of Pittsburgh, Forbes Tower 4033, Pittsburgh, PA 15260, USA
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Radeloff A, Smolders JWT. Brain-derived neurotrophic factor treatment does not improve functional recovery after hair cell regeneration in the pigeon. Acta Otolaryngol 2006; 126:452-9. [PMID: 16698693 DOI: 10.1080/00016480500437344] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Abstract
CONCLUSIONS Brain-derived neurotrophic factor (BDNF) supply to the inner ear does not improve the time course or the extent of functional recovery after hair cell regeneration. Specifically it does not improve the residual threshold elevation observed after the completion of spontaneous recovery. OBJECTIVE The avian inner ear is capable of hair cell regeneration and substantial functional recovery, but residual hearing deficits remain. We investigated whether functional recovery can be improved by intracochlear application of BDNF, which plays an important role in auditory ontogenesis and maintenance during adult life. METHODS Hair cells in adult pigeons were destroyed by local application of gentamicin. After 3 days either BDNF or control solution was administered to the scala tympani by implanted osmotic minipumps for 8 weeks. Auditory brain stem responses (ABR) to tone pips were used to assess recovery of hearing thresholds in both groups. RESULTS The application of gentamicin caused a frequency-dependent hearing loss that ranged from 24.8 dB SPL at low frequencies to 66.2 dB SPL at high frequencies. After day 10 substantial recovery was observed, but a significant threshold shift remained. The time course of recovery in the control and BDNF-treated groups was similar, without significant residual threshold differences in any frequency range.
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Affiliation(s)
- A Radeloff
- Physiologisches Institut II, Zentrum der Hals-Nasen-Ohrenheilkunde, Frankfurt am Main, Germany
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Magnusson AK, Tham R. Reversible and controlled peripheral vestibular loss by continuous infusion of ropivacaine (Narop) into the round window niche of rats. Neurosci Lett 2006; 400:16-20. [PMID: 16503375 DOI: 10.1016/j.neulet.2006.02.011] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/01/2005] [Revised: 01/10/2006] [Accepted: 02/06/2006] [Indexed: 11/19/2022]
Abstract
This paper describes a method for achieving a peripheral vestibular blockade in rats by instillation of local anaesthetics over the round window membrane through a permanently implanted cannula. Being rapidly reversible, the effect of the anaesthetic drug is easily controlled by a single continuous infusion, which can be repeated at any time. The method offers a unique opportunity to study the consequence of single or repeated transient vestibular loss without any use of general anaesthetics, which may be a severe confounding factor. Such studies might shed light on balance disorders related to permanent vestibular loss or episodic vestibular dysfunction. To evaluate the method, spontaneous horizontal eye movements were recorded during the first 4 h of continuous infusion. Unilateral infusion of ropivacaine gave rise to a high-frequency spontaneous nystagmus, reaching levels that have not been documented after a surgical labyrinthectomy under general anaesthesia. This vestibulo-oculomotor behaviour is consistent with a previous report using a single intratympanic instillation of lidocaine to achieve a short-lasting vestibular blockade. In the present study, it was demonstrated that the initial high-frequency nystagmus decreased during the first 100 min of infusion before stabilizing at the same level as recorded when the effect of general anaesthesia has worn off after a surgical ablation. When the transient vestibular blockade was repeated by a second infusion during the following day, the nystagmus frequency saturated on a significantly lower level than during the first blockade. Also, serial single infusions, with recovery between each functional vestibular loss, gave rise to a less severe nystagmus. It is suggested that this phenomenon is an expression of the behavioural concept of 'vestibular habituation', the neural substrate of which is rather unknown.
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Affiliation(s)
- Anna K Magnusson
- Department of Neuroscience and Locomotion, Faculty of Health Sciences, SE-581 85 Linköping, Sweden.
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Garnham C, Reetz G, Jolly C, Miller J, Salt A, Beal F. Drug delivery to the cochlea after implantation: consideration of the risk factors. Cochlear Implants Int 2006. [DOI: 10.1002/cii.273] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/10/2022]
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Paasche G, Bögel L, Leinung M, Lenarz T, Stöver T. Substance distribution in a cochlea model using different pump rates for cochlear implant drug delivery electrode prototypes. Hear Res 2005; 212:74-82. [PMID: 16337758 DOI: 10.1016/j.heares.2005.10.013] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/12/2005] [Revised: 10/31/2005] [Accepted: 10/31/2005] [Indexed: 12/16/2022]
Abstract
Several studies using animals have shown the protective effects of neurotrophic factors (NF) on spiral ganglion cells (SGC). This is of particular importance since the number of SGCs is considered to be among the factors defining the efficacy of cochlear implants. A device for local inner ear treatment is therefore of great interest. As described previously, we modified a Contour(TM) cochlear implant electrode, to examine the inbuilt canal to be used for fluid release [Paasche, G., Gibson, P., Averbeck, T., Becker, H., Lenarz, T., Stöver, T., 2003. Technical report: modification of a cochlear implant electrode for drug delivery to the inner ear. Otol. Neurotol. 24, 222-227]. In the present study, three different electrode prototypes with openings of the delivery channel at various locations along the electrode array were examined to determine distribution of dye in a cochlea model over time. We compared dye delivery with: (a) release of the dye at the tip, (b) release of the dye at the tip and the side of the electrode, and (c) release of the dye only at the side of the electrode (6 mm from the tip). A mechanical pump was used to drive the system at pump rates of 100, 10, and 1 microl/h. Dye concentration changes along the length of the whole cochlea were investigated. Mean values for all experimental conditions show that the distribution along the array is fastest with two outlets whereas the distribution via a single outlet at the side of the electrode array is not considered to be sufficient. The established experimental setup provides the possibility of investigating prototypes of a fluid based drug delivery system for the treatment of inner ear pathologies in combination with electrical stimulation.
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Affiliation(s)
- Gerrit Paasche
- Department of Otolaryngology, Medical University of Hannover, OE 6500, Carl-Neuberg-Strasse 1, 30625 Hannover, Germany.
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Chen Z, Kujawa SG, McKenna MJ, Fiering JO, Mescher MJ, Borenstein JT, Leary Swan EE, Sewell WF. Inner ear drug delivery via a reciprocating perfusion system in the guinea pig. J Control Release 2005; 110:1-19. [PMID: 16274830 PMCID: PMC2030590 DOI: 10.1016/j.jconrel.2005.09.003] [Citation(s) in RCA: 58] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2005] [Accepted: 09/08/2005] [Indexed: 10/25/2022]
Abstract
Rapid progress in understanding the molecular mechanisms associated with cochlear and auditory nerve degenerative processes offers hope for the development of gene-transfer and molecular approaches to treat these diseases in patients. For therapies based on these discoveries to become clinically useful, it will be necessary to develop safe and reliable mechanisms for the delivery of drugs into the inner ear, bypassing the blood-labyrinthine barrier. Toward the goal of developing an inner ear perfusion device for human use, a reciprocating microfluidic system that allows perfusion of drugs into the cochlear perilymph through a single inlet hole in scala tympani of the basal turn was developed. The performance of a prototype, extracorporeal reciprocating perfusion system in guinea pigs is described. Analysis of the cochlear distribution of compounds after perfusion took advantage of the place-dependent generation of responses to tones along the length of the cochlea. Perfusion with a control artificial perilymph solution had no effect. Two drugs with well-characterized effects on cochlear physiology, salicylate (5 mM) and DNQX (6,7-Dinitroquinoxaline-2,3-dione; 100 and 300 microM), reversibly altered responses. The magnitude of drug effect decreased with distance from the perfusion pipette for up to 10 mm, and increased with dose and length of application.
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Affiliation(s)
- Zhiqiang Chen
- Department of Otology and Laryngology, Harvard Medical School, Boston, MA 02114, United States
- Eaton Peabody Laboratory, Massachusetts Eye and Ear Infirmary, 243 Charles St., Boston, MA 02114, United States
- Department of Otolaryngology, MEEI, 243 Charles St., Boston, MA 02114, United States
| | - Sharon G. Kujawa
- Department of Otology and Laryngology, Harvard Medical School, Boston, MA 02114, United States
- Eaton Peabody Laboratory, Massachusetts Eye and Ear Infirmary, 243 Charles St., Boston, MA 02114, United States
- Department of Audiology, Massachusetts Eye and Ear Infirmary, 243 Charles St., Boston, MA 02114, United States
- Department of Otolaryngology, MEEI, 243 Charles St., Boston, MA 02114, United States
| | - Michael J. McKenna
- Department of Otology and Laryngology, Harvard Medical School, Boston, MA 02114, United States
- Department of Otolaryngology, MEEI, 243 Charles St., Boston, MA 02114, United States
| | - Jason O. Fiering
- Charles Stark Draper Laboratory, 555 Technology Square Cambridge, MA 02139, United States
| | - Mark J. Mescher
- Charles Stark Draper Laboratory, 555 Technology Square Cambridge, MA 02139, United States
| | - Jeffrey T. Borenstein
- Charles Stark Draper Laboratory, 555 Technology Square Cambridge, MA 02139, United States
| | - Erin E. Leary Swan
- Charles Stark Draper Laboratory, 555 Technology Square Cambridge, MA 02139, United States
- Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139, United States
| | - William F. Sewell
- Department of Otology and Laryngology, Harvard Medical School, Boston, MA 02114, United States
- Eaton Peabody Laboratory, Massachusetts Eye and Ear Infirmary, 243 Charles St., Boston, MA 02114, United States
- Program in Neuroscience, Harvard Medical School, United States
- Department of Otolaryngology, MEEI, 243 Charles St., Boston, MA 02114, United States
- * Corresponding author. Eaton Peabody Laboratory, Massachusetts Eye and Ear Infirmary, 243 Charles St., Boston, MA 02114, United States. Tel.: +1 617 573 3156; fax: +1 617 720 4408. E-mail address: (W.F. Sewell)
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Abstract
Several drugs that are applied directly to the inner ear are in widespread clinical use for the treatment of inner-ear disorders. Many new substances and drug delivery systems specific to the inner ear are under development and in some cases are being evaluated in animal experiments and in clinical studies. However, the pharmacokinetics of drugs in the inner ear is not well defined and the field is plagued by technical problems in obtaining pure samples of the inner-ear fluids for analysis. Nevertheless, a basic understanding of the mechanisms of drug dispersal in the inner ear has emerged, which facilitates the design and interpretation of future pharmacokinetic studies.
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Affiliation(s)
- Alec N Salt
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, MO 63110, USA.
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Barkdull GC, Vu C, Keithley EM, Harris JP. Cochlear microperfusion: experimental evaluation of a potential new therapy for severe hearing loss caused by inflammation. Otol Neurotol 2005; 26:19-26. [PMID: 15699715 DOI: 10.1097/00129492-200501000-00005] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
HYPOTHESIS Cochlear microperfusion will be a useful treatment of severe sensorineural hearing loss caused by inflammation. BACKGROUND Viruses, bacteria, and autoimmunity can initiate inflammation in the inner ear. The acute phase is associated with elevations in cytokines, nitrous oxide, and cellular infiltrates and the breakdown of the blood-labyrinthine barrier. The chronic phase leads to irreversible ossification of the labyrinth. METHODS The authors developed cochlear microperfusion to facilitate removal of inflammatory cells and their byproducts during the acute phase of inflammation. Using a ventral approach to the guinea pig cochlea, the authors displaced resident perilymph by delivering perfusate into the scala vestibuli and collecting the effluent from the scala tympani. The authors evaluated the benefit of the procedure in an animal model of severe hearing loss caused by inflammation. RESULTS Healthy controls undergoing cochlear microperfusion with phosphate-buffered saline incurred a mean hearing loss of 16 dB (n=4). This hearing loss was associated with the creation of two cochleostomies and not the perfusion itself. Sterile labyrinthitis (n=5) generated by perfusion of the cochlea with antigen consistently produced severe hearing loss over the initial 48 hours, and this hearing loss persisted for the subsequent 7 days. Therapeutic cochlear microperfusion, performed within the first 24 hours of developing severe hearing loss (n=9), immediately restored on average 24 dB (p <0.007) of hearing. CONCLUSION Cochlear microperfusion is a promising new technique for treating severe deafness caused by inflammation. The benefit may be sustained when combined with local delivery of immunosuppressive agents to the inner ear.
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Affiliation(s)
- Gregory C Barkdull
- Division of Otolaryngology-Head and Neck Surgery, Department of Surgery, University of California, San Diego, School of Medicine, 92103-8895, USA
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Maeda Y, Fukushima K, Nishizaki K, Smith RJH. In vitro and in vivo suppression of GJB2 expression by RNA interference. Hum Mol Genet 2005; 14:1641-50. [PMID: 15857852 DOI: 10.1093/hmg/ddi172] [Citation(s) in RCA: 86] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022] Open
Abstract
Mutations in GJB2 (gap junction protein, beta-2) are the major cause of autosomal recessive non-syndromic hearing loss. A few allele variants of this gene also cause autosomal dominant non-syndromic hearing loss as a dominant-negative consequence of expression of the mutant protein. Allele-specific gene suppression by RNA interference (RNAi) is a potentially attractive strategy to prevent hearing loss caused by this mechanism. In this proof-of-principle study, we identified a potent GJB2-targeting short interfering RNA (siRNA) to post-transcriptionally silence the expression of the R75W allele variant of GJB2 in cultured mammalian cells. In a mouse model, this siRNA duplex selectively suppressed GJB2(R75W) expression by >70% of control levels, thereby preventing hearing loss. The level of endogenous murine Gjb2 expression was not affected. Our data show that RNAi can be used with specificity and efficiency in vivo to protect against hearing loss caused as a dominant-negative consequence of mutant gene expression.
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Affiliation(s)
- Yukihide Maeda
- Molecular Otolaryngology Research Laboratory, Department of Otolaryngology-Head and Neck Surgery, Interdepartmental Ph.D. Genetics Program, The University of Iowa, 200 Hawkins Drive-21151 PFP, Iowa City, IA 52242, USA
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