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Singh J, Randle MR, Walters BJ, Cox BC. The transcription factor Pou4f3 is essential for the survival of postnatal and adult mouse cochlear hair cells and normal hearing. Front Cell Neurosci 2024; 18:1369282. [PMID: 38566840 PMCID: PMC10985149 DOI: 10.3389/fncel.2024.1369282] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 02/26/2024] [Indexed: 04/04/2024] Open
Abstract
Introduction Hair cells (HCs) of the cochlea are responsible for sound transduction and hearing perception in mammals. Genetic mutations in the transcription factor Pou4f3 cause non-syndromic autosomal dominant hearing loss in humans (DFNA15) which varies in the age of onset depending on the individual mutation. Mouse models with germline deletion or mutations in Pou4f3 have previously demonstrated its critical role in the maturation and survival of cochlear HCs during embryonic development. However, the role of Pou4f3 in auditory function and in the survival or maintenance of cochlear HCs after birth and during adulthood has not been studied. Methods Therefore, using the inducible CreER-loxP system, we deleted Pou4f3 from mouse cochlear HCs at different postnatal ages, relevant to specific stages of HC maturation and hearing function. Results and discussion Elevated auditory brainstem response thresholds and significant HC loss were detected in mice with Pou4f3 deletion compared to their control littermates, regardless of the age when Pou4f3 was deleted. However, HC loss occurred more rapidly when Pou4f3 was deleted from immature HCs. Additionally, HC loss caused by Pou4f3 deletion did not affect the number of cochlear supporting cells, but caused a delayed loss of spiral ganglion neurons at 4 months after the deletion. In conclusion, Pou4f3 is necessary for the survival of cochlear HCs and normal hearing at all postnatal ages regardless of their maturation state. Our data also suggest that Pou4f3 indirectly regulates the survival of spiral ganglion neurons.
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Affiliation(s)
- Jarnail Singh
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, United States
| | - Michelle R. Randle
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, United States
| | - Bradley J. Walters
- Department of Otolaryngology-Head and Neck Surgery, University of Mississippi Medical Center, Jackson, MS, United States
| | - Brandon C. Cox
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL, United States
- Department of Otolaryngology, Southern Illinois University School of Medicine, Springfield, IL, United States
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2
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Liu Y, Yang L, Singh S, Beyer LA, Prieskorn DM, Swiderski DL, Groves AK, Raphael Y. Combinatorial Atoh1, Gfi1, Pou4f3, and Six1 gene transfer induces hair cell regeneration in the flat epithelium of mature guinea pigs. Hear Res 2024; 441:108916. [PMID: 38103445 PMCID: PMC11223172 DOI: 10.1016/j.heares.2023.108916] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/05/2023] [Revised: 10/29/2023] [Accepted: 11/14/2023] [Indexed: 12/19/2023]
Abstract
Flat epithelium (FE) is a condition characterized by the loss of both hair cells (HCs) and supporting cells and the transformation of the organ of Corti into a simple flat or cuboidal epithelium, which can occur after severe cochlear insults. The transcription factors Gfi1, Atoh1, Pou4f3, and Six1 (GAPS) play key roles in HC differentiation and survival in normal ears. Previous work using a single transcription factor, Atoh1, to induce HC regeneration in mature ears in vivo usually produced very few cells and failed to produce HCs in severely damaged organs of Corti, especially those with FE. Studies in vitro suggested combinations of transcription factors may be more effective than any single factor, thus the current study aims to examine the effect of co-overexpressing GAPS genes in deafened mature guinea pig cochleae with FE. Deafening was achieved through the infusion of neomycin into the perilymph, leading to the formation of FE and substantial degeneration of nerve fibers. Seven days post neomycin treatment, adenovirus vectors carrying GAPS were injected into the scala media and successfully expressed in the FE. One or two months following GAPS inoculation, cells expressing Myosin VIIa were observed in regions under the FE (located at the scala tympani side of the basilar membrane), rather than within the FE. The number of cells, which we define as induced HCs (iHCs), was not significantly different between one and two months, but the larger N at two months made it more apparent that there were significantly more iHCs in GAPS treated animals than in controls. Additionally, qualitative observations indicated that ears with GAPS gene expression in the FE had more nerve fibers than FE without the treatment. In summary, our results showed that co-overexpression of GAPS enhances the potential for HC regeneration in a severe lesion model of FE.
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Affiliation(s)
- Yujie Liu
- Kresge Hearing Research Institute, Department of Otolaryngology-Head and Neck Surgery, University of Michigan, Ann Arbor, MI, USA; Department of Otolaryngology-Head and Neck Surgery, Beijing Tongren Hospital, Capital Medical University, Ministry of Education Key Laboratory of Otolaryngology-Head and Neck Surgery, Beijing 100730, China
| | - Lin Yang
- Kresge Hearing Research Institute, Department of Otolaryngology-Head and Neck Surgery, University of Michigan, Ann Arbor, MI, USA; Department of Otolaryngology-Head and Neck Surgery, Beijing Tiantan Hospital, Capital Medical University, Beijing 100070, China
| | - Sunita Singh
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA
| | - Lisa A Beyer
- Kresge Hearing Research Institute, Department of Otolaryngology-Head and Neck Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Diane M Prieskorn
- Kresge Hearing Research Institute, Department of Otolaryngology-Head and Neck Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Donald L Swiderski
- Kresge Hearing Research Institute, Department of Otolaryngology-Head and Neck Surgery, University of Michigan, Ann Arbor, MI, USA
| | - Andrew K Groves
- Department of Neuroscience, Baylor College of Medicine, Houston, Texas, USA; Department of Molecular and Human Genetics, Baylor College of Medicine, Houston, Texas, USA
| | - Yehoash Raphael
- Kresge Hearing Research Institute, Department of Otolaryngology-Head and Neck Surgery, University of Michigan, Ann Arbor, MI, USA.
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3
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Kaur C, Van Orden M, O'Malley JT, Wu PZ, Liberman MC. Supporting-cell vs. hair-cell survival in the human cochlea: Implications for regenerative therapies. Hear Res 2023; 435:108815. [PMID: 37263113 PMCID: PMC10426718 DOI: 10.1016/j.heares.2023.108815] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2023] [Revised: 05/15/2023] [Accepted: 05/24/2023] [Indexed: 06/03/2023]
Abstract
Animal studies have shown that the supporting-cells surviving in the organ of Corti after cochlear insult can be transdifferentiated into hair cells as a treatment for sensorineural hearing loss. Clinical trials of small-molecule therapeutics have been undertaken, but little is known about how to predict the pattern and degree of supporting-cell survival based on audiogram, hearing loss etiology or any other metric obtainable pre-mortem. To address this, we systematically assessed supporting-cell and hair cell survival, as a function of cochlear location in 274 temporal bone cases from the archives at the Massachusetts Eye and Ear and compared the histopathology with the audiograms and hearing-loss etiologies. Results showed that supporting-cell survival was always significantly greater in the apical half than the basal half of the cochlea, that inner pillars were more robust than outer pillars or Deiters' cells, and that total replacement of all supporting cells with a flat epithelium was rare outside of the extreme basal 20% of the cochlea. Supporting cell survival in the basal half of the cochlea was better correlated with the slope of the audiogram than with the mean high-frequency threshold per se: i.e. survival was better with flatter audiograms than with steeply down-sloping audiograms. Cochlear regions with extensive hair cell loss and exceptional supporting cell survival were most common in cases with hearing loss due to ototoxic drugs. Such cases also tended to have less pathology in other functionally critical structures, i.e. spiral ganglion neurons and the stria vascularis.
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Affiliation(s)
- Charanjeet Kaur
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Dept of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, MA 02115, USA.
| | | | - Jennifer T O'Malley
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA 02114, USA
| | - Pei-Zhe Wu
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Dept of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, MA 02115, USA
| | - M Charles Liberman
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114, USA; Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA 02114, USA; Dept of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, MA 02115, USA
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4
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Smith-Cortinez N, Tan AK, Stokroos RJ, Versnel H, Straatman LV. Regeneration of Hair Cells from Endogenous Otic Progenitors in the Adult Mammalian Cochlea: Understanding Its Origins and Future Directions. Int J Mol Sci 2023; 24:ijms24097840. [PMID: 37175547 PMCID: PMC10177935 DOI: 10.3390/ijms24097840] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 04/20/2023] [Accepted: 04/21/2023] [Indexed: 05/15/2023] Open
Abstract
Sensorineural hearing loss is caused by damage to sensory hair cells and/or spiral ganglion neurons. In non-mammalian species, hair cell regeneration after damage is observed, even in adulthood. Although the neonatal mammalian cochlea carries regenerative potential, the adult cochlea cannot regenerate lost hair cells. The survival of supporting cells with regenerative potential after cochlear trauma in adults is promising for promoting hair cell regeneration through therapeutic approaches. Targeting these cells by manipulating key signaling pathways that control mammalian cochlear development and non-mammalian hair cell regeneration could lead to regeneration of hair cells in the mammalian cochlea. This review discusses the pathways involved in the development of the cochlea and the impact that trauma has on the regenerative capacity of the endogenous progenitor cells. Furthermore, it discusses the effects of manipulating key signaling pathways targeting supporting cells with progenitor potential to promote hair cell regeneration and translates these findings to the human situation. To improve hearing recovery after hearing loss in adults, we propose a combined approach targeting (1) the endogenous progenitor cells by manipulating signaling pathways (Wnt, Notch, Shh, FGF and BMP/TGFβ signaling pathways), (2) by manipulating epigenetic control, and (3) by applying neurotrophic treatments to promote reinnervation.
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Affiliation(s)
- Natalia Smith-Cortinez
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
- UMC Utrecht Brain Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - A Katherine Tan
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
- UMC Utrecht Brain Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - Robert J Stokroos
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
- UMC Utrecht Brain Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - Huib Versnel
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
- UMC Utrecht Brain Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - Louise V Straatman
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht University, Heidelberglaan 100, 3584 CX Utrecht, The Netherlands
- UMC Utrecht Brain Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
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5
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Kaur C, Van Orden M, O’Malley JT, Wu PZ, Liberman MC. Supporting-cell vs. hair-cell survival in the human cochlea: Implications for regenerative therapies. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.04.24.538119. [PMID: 37163013 PMCID: PMC10168255 DOI: 10.1101/2023.04.24.538119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/11/2023]
Abstract
Animal studies have shown that the supporting-cells surviving in the organ of Corti after cochlear insult can be transdifferentiated into hair cells as a treatment for sensorineural hearing loss. Clinical trials of small-molecule therapeutics have been undertaken, but little is known about how to predict the pattern and degree of supporting-cell survival based on audiogram, hearing loss etiology or any other metric obtainable pre-mortem. To address this, we systematically assessed supporting-cell and hair cell survival, as a function of cochlear location in 274 temporal bone cases from the archives at the Massachusetts Eye and Ear and compared the histopathology with the audiograms and hearing-loss etiologies. Results showed that supporting-cell survival was always significantly greater in the apical half than the basal half of the cochlea, that inner pillars were more robust than outer pillars or Deiters' cells, and that total replacement of all supporting cells with a flat epithelium was rare outside of the extreme basal 20% of the cochlea. Supporting cell survival in the basal half of the cochlea was better correlated with the slope of the audiogram than with the mean high-frequency threshold per se: i.e. survival was better with flatter audiograms than with steeply down-sloping audiograms. Cochlear regions with extensive hair cell loss and exceptional supporting cell survival were most common in cases with hearing loss due to ototoxic drugs. Such cases also tended to have less pathology in other functionally critical structures, i.e. spiral ganglion neurons and the stria vascularis. Highlights Supporting cell survival was systematically assessed in 274 human cochleasSupporting cell survival was better with flat than with down-sloping audiogramsSupporting cell survival was most robust when hearing loss was from ototoxic drugsOtotoxic cases also showed less pathology in other critical cochlear structuresThe data can inform clinical trials for regeneration via supporting cell conversion.
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Affiliation(s)
- Charanjeet Kaur
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114
- Dept of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, MA 02115
| | | | - Jennifer T. O’Malley
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114
- Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA 02114
| | - Pei-zhe Wu
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114
- Dept of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, MA 02115
| | - M. Charles Liberman
- Eaton-Peabody Laboratories, Massachusetts Eye and Ear, Boston, MA 02114
- Otopathology Laboratory, Massachusetts Eye and Ear, Boston, MA 02114
- Dept of Otolaryngology-Head & Neck Surgery, Harvard Medical School, Boston, MA 02115
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6
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Ontogeny of cellular organization and LGR5 expression in porcine cochlea revealed using tissue clearing and 3D imaging. iScience 2022; 25:104695. [PMID: 35865132 PMCID: PMC9294204 DOI: 10.1016/j.isci.2022.104695] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2022] [Revised: 04/20/2022] [Accepted: 06/27/2022] [Indexed: 11/23/2022] Open
Abstract
Over 11% of the world's population experience hearing loss. Although there are promising studies to restore hearing in rodent models, the size, ontogeny, genetics, and frequency range of hearing of most rodents' cochlea do not match that of humans. The porcine cochlea can bridge this gap as it shares many anatomical, physiological, and genetic similarities with its human counterpart. Here, we provide a detailed methodology to process and image the porcine cochlea in 3D using tissue clearing and light-sheet microscopy. The resulting 3D images can be employed to compare cochleae across different ages and conditions, investigate the ontogeny of cochlear cytoarchitecture, and produce quantitative expression maps of LGR5, a marker of cochlear progenitors in mice. These data reveal that hair cell organization, inner ear morphology, cellular cartography in the organ of Corti, and spatiotemporal expression of LGR5 are dynamic over developmental stages in a pattern not previously documented.
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7
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Jang MW, Lim J, Park MG, Lee JH, Lee CJ. Active role of glia-like supporting cells in the organ of Corti: Membrane proteins and their roles in hearing. Glia 2022; 70:1799-1825. [PMID: 35713516 DOI: 10.1002/glia.24229] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2022] [Revised: 05/23/2022] [Accepted: 05/30/2022] [Indexed: 12/13/2022]
Abstract
The organ of Corti, located in the cochlea in the inner ear, is one of the major sensory organs involved in hearing. The organ of Corti consists of hair cells, glia-like supporting cells, and the cochlear nerve, which work in harmony to receive sound from the outer ear and transmit auditory signals to the cochlear nucleus in the auditory ascending pathway. In this process, maintenance of the endocochlear potential, with a high potassium gradient and clearance of electrolytes and biochemicals in the inner ear, is critical for normal sound transduction. There is an emerging need for a thorough understanding of each cell type involved in this process to understand the sophisticated mechanisms of the organ of Corti. Hair cells have long been thought to be active, playing a primary role in the cochlea in actively detecting and transmitting signals. In contrast, supporting cells are thought to be silent and function to support hair cells. However, growing lines of evidence regarding the membrane proteins that mediate ionic movement in supporting cells have demonstrated that supporting cells are not silent, but actively play important roles in normal signal transduction. In this review, we summarize studies that characterize diverse membrane proteins according to the supporting cell subtypes involved in cochlear physiology and hearing. This review contributes to a better understanding of supporting cell functions and facilitates the development of potential therapeutic tools for hearing loss.
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Affiliation(s)
- Minwoo Wendy Jang
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea.,Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea
| | - Jiwoon Lim
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea.,IBS School, University of Science and Technology (UST), Daejeon, Republic of Korea
| | - Mingu Gordon Park
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea.,Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea
| | - Jae-Hun Lee
- Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea
| | - C Justin Lee
- KU-KIST Graduate School of Converging Science and Technology, Korea University, Seoul, Republic of Korea.,Center for Cognition and Sociality, Institute for Basic Science (IBS), Daejeon, Republic of Korea.,IBS School, University of Science and Technology (UST), Daejeon, Republic of Korea
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8
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Chan J, Telang R, Kociszewska D, Thorne PR, Vlajkovic SM. A High-Fat Diet Induces Low-Grade Cochlear Inflammation in CD-1 Mice. Int J Mol Sci 2022; 23:ijms23095179. [PMID: 35563572 PMCID: PMC9101486 DOI: 10.3390/ijms23095179] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/07/2022] [Revised: 05/02/2022] [Accepted: 05/04/2022] [Indexed: 02/04/2023] Open
Abstract
There is growing evidence for a relationship between gut dysbiosis and hearing loss. Inflammatory bowel disease, diet-induced obesity (DIO), and type 2 diabetes have all been linked to hearing loss. Here, we investigated the effect of a chronic high-fat diet (HFD) on the development of inner ear inflammation using a rodent model. Three-week-old CD-1 (Swiss) mice were fed an HFD or a control diet for ten weeks. After ten weeks, mouse cochleae were harvested, and markers of cochlear inflammation were assessed at the protein level using immunohistochemistry and at the gene expression level using quantitative real-time RT-PCR. We identified increased immunoexpression of pro-inflammatory biomarkers in animals on an HFD, including intracellular adhesion molecule 1 (ICAM1), interleukin 6 receptor α (IL6Rα), and toll-like-receptor 2 (TLR2). In addition, increased numbers of ionized calcium-binding adapter molecule 1 (Iba1) positive macrophages were found in the cochlear lateral wall in mice on an HFD. In contrast, gene expression levels of inflammatory markers were not affected by an HFD. The recruitment of macrophages to the cochlea and increased immunoexpression of inflammatory markers in mice fed an HFD provide direct evidence for the association between HFD and cochlear inflammation.
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9
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Elliott KL, Fritzsch B, Yamoah EN, Zine A. Age-Related Hearing Loss: Sensory and Neural Etiology and Their Interdependence. Front Aging Neurosci 2022; 14:814528. [PMID: 35250542 PMCID: PMC8891613 DOI: 10.3389/fnagi.2022.814528] [Citation(s) in RCA: 14] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/13/2021] [Accepted: 01/03/2022] [Indexed: 12/19/2022] Open
Abstract
Age-related hearing loss (ARHL) is a common, increasing problem for older adults, affecting about 1 billion people by 2050. We aim to correlate the different reductions of hearing from cochlear hair cells (HCs), spiral ganglion neurons (SGNs), cochlear nuclei (CN), and superior olivary complex (SOC) with the analysis of various reasons for each one on the sensory deficit profiles. Outer HCs show a progressive loss in a basal-to-apical gradient, and inner HCs show a loss in a apex-to-base progression that results in ARHL at high frequencies after 70 years of age. In early neonates, SGNs innervation of cochlear HCs is maintained. Loss of SGNs results in a considerable decrease (~50% or more) of cochlear nuclei in neonates, though the loss is milder in older mice and humans. The dorsal cochlear nuclei (fusiform neurons) project directly to the inferior colliculi while most anterior cochlear nuclei reach the SOC. Reducing the number of neurons in the medial nucleus of the trapezoid body (MNTB) affects the interactions with the lateral superior olive to fine-tune ipsi- and contralateral projections that may remain normal in mice, possibly humans. The inferior colliculi receive direct cochlear fibers and second-order fibers from the superior olivary complex. Loss of the second-order fibers leads to hearing loss in mice and humans. Although ARHL may arise from many complex causes, HC degeneration remains the more significant problem of hearing restoration that would replace the cochlear implant. The review presents recent findings of older humans and mice with hearing loss.
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Affiliation(s)
- Karen L. Elliott
- Department of Biology, University of Iowa, Iowa City, IA, United States
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, IA, United States
- *Correspondence: Bernd Fritzsch
| | - Ebenezer N. Yamoah
- Department of Physiology and Cell Biology, School of Medicine, University of Nevada, Reno, NV, United States
| | - Azel Zine
- LBN, Laboratory of Bioengineering and Nanoscience, University of Montpellier, Montpellier, France
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Tisi A, Rovers J, Vink HA, Ramekers D, Maccarone R, Versnel H. No Protective Effects of Hair Cells or Supporting Cells in Ototoxically Deafened Guinea Pigs upon Administration of BDNF. Brain Sci 2021; 12:2. [PMID: 35053747 PMCID: PMC8773526 DOI: 10.3390/brainsci12010002] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2021] [Revised: 12/16/2021] [Accepted: 12/17/2021] [Indexed: 11/16/2022] Open
Abstract
We investigated whether treatment with brain-derived neurotrophic factor (BDNF), which is known to protect spiral ganglion cells (SGCs), could also protect hair cells (HCs) and supporting cells (SCs) in the organ of Corti of a guinea pig model of sensorineural hearing loss. Hearing loss was induced by administration of kanamycin/furosemide and two BDNF treatments were performed: (1) by gelatin sponge (BDNF-GS) with acute cochlear implantation (CI), and (2) through a mini-osmotic pump (BDNF-OP) with chronic CI. Outer HCs (OHCs), inner HCs (IHCs), Border, Phalangeal, Pillar, Deiters', and Hensen's cells were counted. The BDNF-GS cochleas had significantly fewer OHCs compared to the untreated ones, while the IHC and SC numbers did not differ between treated and untreated cochleas. The BDNF-OP group showed similar cell numbers to the untreated group. SGC packing density was not correlated with the total number of SCs for either BDNF group. Our data suggest that: (1) BDNF does not prevent cell death in the organ of Corti, and that the protection of SGCs could result from a direct targeting by BDNF; (2) BDNF might induce a different function/activity of the remaining cells in the organ of Corti (independently from cell number).
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Affiliation(s)
- Annamaria Tisi
- Department of Applied Clinical Sciences and Biotechnology, University of L′Aquila, 67100 L′Aquila, Italy; (A.T.); (R.M.)
| | - Jochebed Rovers
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht University, Room G.02.531, P.O. Box 85500, 3508 GA Utrecht, The Netherlands; (J.R.); (H.A.V.); (D.R.)
| | - Henk A. Vink
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht University, Room G.02.531, P.O. Box 85500, 3508 GA Utrecht, The Netherlands; (J.R.); (H.A.V.); (D.R.)
- UMC Utrecht Brain Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - Dyan Ramekers
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht University, Room G.02.531, P.O. Box 85500, 3508 GA Utrecht, The Netherlands; (J.R.); (H.A.V.); (D.R.)
- UMC Utrecht Brain Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
| | - Rita Maccarone
- Department of Applied Clinical Sciences and Biotechnology, University of L′Aquila, 67100 L′Aquila, Italy; (A.T.); (R.M.)
| | - Huib Versnel
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht University, Room G.02.531, P.O. Box 85500, 3508 GA Utrecht, The Netherlands; (J.R.); (H.A.V.); (D.R.)
- UMC Utrecht Brain Center, Utrecht University, Universiteitsweg 100, 3584 CG Utrecht, The Netherlands
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11
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Smith-Cortinez N, Yadak R, Hendriksen FGJ, Sanders E, Ramekers D, Stokroos RJ, Versnel H, Straatman LV. LGR5-Positive Supporting Cells Survive Ototoxic Trauma in the Adult Mouse Cochlea. Front Mol Neurosci 2021; 14:729625. [PMID: 34675775 PMCID: PMC8523910 DOI: 10.3389/fnmol.2021.729625] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2021] [Accepted: 09/07/2021] [Indexed: 11/13/2022] Open
Abstract
Sensorineural hearing loss is mainly caused by irreversible damage to sensory hair cells (HCs). A subgroup of supporting cells (SCs) in the cochlea express leucine-rich repeat-containing G-protein coupled receptor 5 (LGR5), a marker for tissue-resident stem cells. LGR5+ SCs could be used as an endogenous source of stem cells for regeneration of HCs to treat hearing loss. Here, we report long-term presence of LGR5+ SCs in the mature adult cochlea and survival of LGR5+ SCs after severe ototoxic trauma characterized by partial loss of inner HCs and complete loss of outer HCs. Surviving LGR5+ SCs (confirmed by GFP expression) were located in the third row of Deiters' cells. We observed a change in the intracellular localization of GFP, from the nucleus in normal-hearing to cytoplasm and membrane in deafened mice. These data suggests that the adult mammalian cochlea possesses properties essential for regeneration even after severe ototoxic trauma.
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Affiliation(s)
- Natalia Smith-Cortinez
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht, Netherlands.,UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
| | - Rana Yadak
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht, Netherlands.,UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
| | - Ferry G J Hendriksen
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht, Netherlands
| | - Eefje Sanders
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht, Netherlands
| | - Dyan Ramekers
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht, Netherlands.,UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
| | - Robert J Stokroos
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht, Netherlands.,UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
| | - Huib Versnel
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht, Netherlands.,UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
| | - Louise V Straatman
- Department of Otorhinolaryngology and Head & Neck Surgery, University Medical Center Utrecht, Utrecht, Netherlands.,UMC Utrecht Brain Center, University Medical Center Utrecht, Utrecht University, Utrecht, Netherlands
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12
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Ding D, Jiang H, Manohar S, Liu X, Li L, Chen GD, Salvi R. Spatiotemporal Developmental Upregulation of Prestin Correlates With the Severity and Location of Cyclodextrin-Induced Outer Hair Cell Loss and Hearing Loss. Front Cell Dev Biol 2021; 9:643709. [PMID: 34109172 PMCID: PMC8181405 DOI: 10.3389/fcell.2021.643709] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2020] [Accepted: 03/08/2021] [Indexed: 11/24/2022] Open
Abstract
2-Hyroxypropyl-beta-cyclodextrin (HPβCD) is being used to treat Niemann-Pick C1, a fatal neurodegenerative disease caused by abnormal cholesterol metabolism. HPβCD slows disease progression, but unfortunately causes severe, rapid onset hearing loss by destroying the outer hair cells (OHC). HPβCD-induced damage is believed to be related to the expression of prestin in OHCs. Because prestin is postnatally upregulated from the cochlear base toward the apex, we hypothesized that HPβCD ototoxicity would spread from the high-frequency base toward the low-frequency apex of the cochlea. Consistent with this hypothesis, cochlear hearing impairments and OHC loss rapidly spread from the high-frequency base toward the low-frequency apex of the cochlea when HPβCD administration shifted from postnatal day 3 (P3) to P28. HPβCD-induced histopathologies were initially confined to the OHCs, but between 4- and 6-weeks post-treatment, there was an unexpected, rapid and massive expansion of the lesion to include most inner hair cells (IHC), pillar cells (PC), peripheral auditory nerve fibers, and spiral ganglion neurons at location where OHCs were missing. The magnitude and spatial extent of HPβCD-induced OHC death was tightly correlated with the postnatal day when HPβCD was administered which coincided with the spatiotemporal upregulation of prestin in OHCs. A second, massive wave of degeneration involving IHCs, PC, auditory nerve fibers and spiral ganglion neurons abruptly emerged 4–6 weeks post-HPβCD treatment. This secondary wave of degeneration combined with the initial OHC loss results in a profound, irreversible hearing loss.
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Affiliation(s)
- Dalian Ding
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, United States
| | - Haiyan Jiang
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, United States
| | - Senthilvelan Manohar
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, United States
| | - Xiaopeng Liu
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, United States
| | - Li Li
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, United States
| | - Guang-Di Chen
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, United States
| | - Richard Salvi
- Center for Hearing and Deafness, University at Buffalo, Buffalo, NY, United States
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13
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He L, Guo JY, Liu K, Wang GP, Gong SS. Research progress on flat epithelium of the inner ear. Physiol Res 2020; 69:775-785. [PMID: 32901490 DOI: 10.33549/physiolres.934447] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022] Open
Abstract
Sensorineural hearing loss and vertigo, resulting from lesions in the sensory epithelium of the inner ear, have a high incidence worldwide. The sensory epithelium of the inner ear may exhibit extreme degeneration and is transformed to flat epithelium (FE) in humans and mice with profound sensorineural hearing loss and/or vertigo. Various factors, including ototoxic drugs, noise exposure, aging, and genetic defects, can induce FE. Both hair cells and supporting cells are severely damaged in FE, and the normal cytoarchitecture of the sensory epithelium is replaced by a monolayer of very thin, flat cells of irregular contour. The pathophysiologic mechanism of FE is unclear but involves robust cell division. The cellular origin of flat cells in FE is heterogeneous; they may be transformed from supporting cells that have lost some features of supporting cells (dedifferentiation) or may have migrated from the flanking region. The epithelial-mesenchymal transition may play an important role in this process. The treatment of FE is challenging given the severe degeneration and loss of both hair cells and supporting cells. Cochlear implant or vestibular prosthesis implantation, gene therapy, and stem cell therapy show promise for the treatment of FE, although many challenges remain to be overcome.
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Affiliation(s)
- L He
- Department of Otolaryngology-Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, China. ,
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14
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Smith KE, Murphy P, Jagger DJ. Divergent membrane properties of mouse cochlear glial cells around hearing onset. J Neurosci Res 2020; 99:679-698. [PMID: 33099767 DOI: 10.1002/jnr.24744] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/26/2020] [Revised: 09/21/2020] [Accepted: 10/05/2020] [Indexed: 11/11/2022]
Abstract
Spiral ganglion neurons (SGNs) are the primary afferent neurons of the auditory system, and together with their attendant glia, form the auditory nerve. Within the cochlea, satellite glial cells (SGCs) encapsulate the cell body of SGNs, whereas Schwann cells (SCs) wrap their peripherally- and centrally-directed neurites. Despite their likely importance in auditory nerve function and homeostasis, the physiological properties of auditory glial cells have evaded description. Here, we characterized the voltage-activated membrane currents of glial cells from the mouse cochlea. We identified a prominent weak inwardly rectifying current in SGCs within cochlear slice preparations (postnatal day P5-P6), which was also present in presumptive SGCs within dissociated cultures prepared from the cochleae of hearing mice (P14-P15). Pharmacological block by Ba2+ and desipramine suggested that channels belonging to the Kir4 family mediated the weak inwardly rectifying current, and post hoc immunofluorescence implicated the involvement of Kir4.1 subunits. Additional electrophysiological profiles were identified for glial cells within dissociated cultures, suggesting that glial subtypes may have specific membrane properties to support distinct physiological roles. Immunofluorescence using fixed cochlear sections revealed that although Kir4.1 is restricted to SGCs after the onset of hearing, these channels are more widely distributed within the glial population earlier in postnatal development (i.e., within both SGCs and SCs). The decrease in Kir4.1 immunofluorescence during SC maturation was coincident with a reduction of Sox2 expression and advancing neurite myelination. The data suggest a diversification of glial properties occurs in preparation for sound-driven activity in the auditory nerve.
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Affiliation(s)
- Katie E Smith
- UCL Ear Institute, University College London, London, UK
| | - Phoebe Murphy
- UCL Ear Institute, University College London, London, UK
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15
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Using Sox2 to alleviate the hallmarks of age-related hearing loss. Ageing Res Rev 2020; 59:101042. [PMID: 32173536 DOI: 10.1016/j.arr.2020.101042] [Citation(s) in RCA: 16] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/19/2019] [Revised: 03/04/2020] [Accepted: 03/05/2020] [Indexed: 02/07/2023]
Abstract
Age-related hearing loss (ARHL) is the most prevalent sensory deficit. ARHL reduces the quality of life of the growing population, setting seniors up for the enhanced mental decline. The size of the needy population, the structural deficit, and a likely research strategy for effective treatment of chronic neurosensory hearing in the elderly are needed. Although there has been profound advancement in auditory regenerative research, there remain multiple challenges to restore hearing loss. Thus, additional investigations are required, using novel tools. We propose how the (1) flat epithelium, remaining after the organ of Corti has deteriorated, can be converted to the repaired-sensory epithelium, using Sox2. This will include (2) developing an artificial gene regulatory network transmitted by (3) large viral vectors to the flat epithelium to stimulate remnants of the organ of Corti to restore hair cells. We hope to unite with our proposal toward the common goal, eventually restoring a functional human hearing organ by transforming the flat epithelial cells left after the organ of Corti loss.
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16
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Büning H, Schambach A, Morgan M, Rossi A, Wichova H, Staecker H, Warnecke A, Lenarz T. Challenges and advances in translating gene therapy for hearing disorders. EXPERT REVIEW OF PRECISION MEDICINE AND DRUG DEVELOPMENT 2020. [DOI: 10.1080/23808993.2020.1707077] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Hildegard Büning
- Institute of Experimental Hematology, Hannover Medical School, Hannover, Germany
- German Center for Infection Research, Braunschweig, Germany
- REBIRTH Cluster of Excellence, Hannover Medical School, Hannover, Germany
| | - Axel Schambach
- Institute of Experimental Hematology, Hannover Medical School, Hannover, Germany
- REBIRTH Cluster of Excellence, Hannover Medical School, Hannover, Germany
- Division of Hematology/Oncology, Boston Children’s Hospital, Harvard Medical School, Boston, MA, USA
| | - Michael Morgan
- Institute of Experimental Hematology, Hannover Medical School, Hannover, Germany
- REBIRTH Cluster of Excellence, Hannover Medical School, Hannover, Germany
| | - Axel Rossi
- Institute of Experimental Hematology, Hannover Medical School, Hannover, Germany
| | - Helena Wichova
- Department of Otolaryngology Head and Neck Surgery, University of Kansas School of Medicine, Kansas City, USA
| | - Hinrich Staecker
- Department of Otolaryngology Head and Neck Surgery, University of Kansas School of Medicine, Kansas City, USA
| | - Athanasia Warnecke
- Department of Otolaryngology, Hannover Medical School, 30625 Hannover, Germany
- Hearing4all Cluster of Excellence, Hannover Medical School, Hannover, Germany
| | - Thomas Lenarz
- Department of Otolaryngology, Hannover Medical School, 30625 Hannover, Germany
- Hearing4all Cluster of Excellence, Hannover Medical School, Hannover, Germany
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17
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Pang J, Xiong H, Ou Y, Yang H, Xu Y, Chen S, Lai L, Ye Y, Su Z, Lin H, Huang Q, Xu X, Zheng Y. SIRT1 protects cochlear hair cell and delays age-related hearing loss via autophagy. Neurobiol Aging 2019; 80:127-137. [PMID: 31170533 DOI: 10.1016/j.neurobiolaging.2019.04.003] [Citation(s) in RCA: 27] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2019] [Revised: 03/29/2019] [Accepted: 04/04/2019] [Indexed: 12/16/2022]
Abstract
Age-related hearing loss (AHL) is typically caused by the irreversible death of hair cells (HCs). Autophagy is a constitutive pathway to strengthen cell survival under normal or stress condition. Our previous work suggested that impaired autophagy played an important role in the development of AHL in C57BL/6 mice, although the underlying mechanism of autophagy in AHL still needs to be investigated. SIRT1 as an important regulator involves in AHL and is also a regulator of autophagy. Thus, we hypothesized that the modulation between SIRT1 and autophagy contribute to HC death and the progressive hearing dysfunction in aging. In the auditory cell line HEI-OC1, SIRT1 modulated autophagosome induction because of SIRT1 deacetylating a core autophagy protein ATG9A. The deacetylation of ATG9A not only affects the autophagosome membrane formation but also acts as a sensor of endoplasmic reticulum (ER) stress inducing autophagy. Moreover, the silencing of SIRT1 facilitated cell death via autophagy inhibition, whereas SIRT1 and autophagy activation reversed the SIRT1 inhibition media cell death. Notably, resveratrol, the first natural agonist of SIRT1, altered the organ of Corti autophagy impairment of the 12-month-old C57BL/6 mice and delayed AHL. The activation of SIRT1 modulates the deacetylation status of ATG9A, which acts as a sensor of ER stress, providing a novel perspective in elucidating the link between ER stress and autophagy in aging. Because SIRT1 activation restores autophagy with reduced HC death and hearing loss, it could be used as a strategy to delay AHL.
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Affiliation(s)
- Jiaqi Pang
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China; Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China; RNA Biomedical Institute, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Hao Xiong
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China; Department of Hearing and Speech Science, Xinhua College, Sun Yat-sen University, Guangzhou, China
| | - Yongkang Ou
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China; Department of Hearing and Speech Science, Xinhua College, Sun Yat-sen University, Guangzhou, China
| | - Haidi Yang
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China; Department of Hearing and Speech Science, Xinhua College, Sun Yat-sen University, Guangzhou, China
| | - Yaodong Xu
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China
| | - Suijun Chen
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China; Department of Hearing and Speech Science, Xinhua College, Sun Yat-sen University, Guangzhou, China
| | - Lan Lai
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China; Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China
| | - Yongyi Ye
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; School of Public Health, Sun Yat-Sen University, Guangzhou, China
| | - Zhongwu Su
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China
| | - Hanqing Lin
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China
| | - Qiuhong Huang
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China; Department of Hearing and Speech Science, Xinhua College, Sun Yat-sen University, Guangzhou, China
| | - Xiaoding Xu
- Guangdong Provincial Key Laboratory of Malignant Tumor Epigenetics and Gene Regulation, Medical Research Center, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China; RNA Biomedical Institute, Sun Yat-Sen Memorial Hospital, Sun Yat-Sen University, Guangzhou, China.
| | - Yiqing Zheng
- Department of Otolaryngology, Sun Yat-sen Memorial Hospital, Sun Yat-sen University, Guangzhou China; Institute of Hearing and Speech-Language Science, Sun Yat-sen University, Guangzhou, China; Department of Hearing and Speech Science, Xinhua College, Sun Yat-sen University, Guangzhou, China.
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18
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Werner M, Van De Water TR, Stenlund H, Berggren D. Ultrastructural Characterization of Stem Cell-Derived Replacement Vestibular Hair Cells Within Ototoxin-Damaged Rat Utricle Explants. Anat Rec (Hoboken) 2019; 303:506-515. [PMID: 31090209 PMCID: PMC7065082 DOI: 10.1002/ar.24148] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/01/2018] [Revised: 08/23/2018] [Accepted: 09/07/2018] [Indexed: 11/25/2022]
Abstract
The auditory apparatus of the inner ear does not show turnover of sensory hair cells (HCs) in adult mammals; in contrast, there are many observations supporting low‐level turnover of vestibular HCs within the balance organs of mammalian inner ears. This low‐level renewal of vestibular HCs exists during normal conditions and it is further enhanced after trauma‐induced loss of these HCs. The main process for renewal of HCs within mammalian vestibular epithelia is a conversion/transdifferentiation of existing supporting cells (SCs) into replacement HCs.In earlier studies using long‐term organ cultures of postnatal rat macula utriculi, HC loss induced by gentamicin resulted in an initial substantial decline in HC density followed by a significant increase in the proportion of HCs to SCs indicating the production of replacement HCs. In the present study, using the same model of ototoxic damage to study renewal of vestibular HCs, we focus on the ultrastructural characteristics of SCs undergoing transdifferentiation into new HCs. Our objective was to search for morphological signs of SC plasticity during this process. In the utricular epithelia, we observed immature HCs, which appear to be SCs transdifferentiating into HCs. These bridge SCs have unique morphological features characterized by formation of foot processes, basal accumulation of mitochondria, and an increased amount of connections with nearby SCs. No gap junctions were observed on these transitional cells. The tight junction seals were morphologically intact in both control and gentamicin‐exposed explants. Anat Rec, 303:506–515, 2020. © 2019 The Authors. The Anatomical Record published by Wiley Periodicals, Inc. on behalf of American Association of Anatomists.
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Affiliation(s)
- Mimmi Werner
- Department of Clinical Sciences, Otolaryngology, University of Umeå, Umeå, Sweden
| | - Thomas R Van De Water
- Cochlear Implant Research Program, Department of Otolaryngology, University of Miami Ear Institute, University of Miami Miller School of Medicine, Miami, Florida
| | - Hans Stenlund
- Department of Epidemiology and Global Health, University of Umeå, Umeå, Sweden
| | - Diana Berggren
- Department of Clinical Sciences, Otolaryngology, University of Umeå, Umeå, Sweden
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19
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Ma Y, Wise AK, Shepherd RK, Richardson RT. New molecular therapies for the treatment of hearing loss. Pharmacol Ther 2019; 200:190-209. [PMID: 31075354 DOI: 10.1016/j.pharmthera.2019.05.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 05/02/2019] [Indexed: 12/11/2022]
Abstract
An estimated 466 million people suffer from hearing loss worldwide. Sensorineural hearing loss is characterized by degeneration of key structures of the sensory pathway in the cochlea such as the sensory hair cells, the primary auditory neurons and their synaptic connection to the hair cells - the ribbon synapse. Various strategies to protect or regenerate these sensory cells and structures are the subject of intensive research. Yet despite recent advances in our understandings of the capacity of the cochlea for repair and regeneration there are currently no pharmacological or biological interventions for hearing loss. Current research focusses on localized cochlear drug, gene and cell-based therapies. One of the more promising drug-based therapies is based on neurotrophic factors for the repair of the ribbon synapse after noise exposure, as well as preventing loss of primary auditory neurons and regrowth of the auditory neuron fibers after severe hearing loss. Drug therapy delivery technologies are being employed to address the specific needs of neurotrophin and other therapies for hearing loss that include the need for high doses, long-term delivery, localised or cell-specific targeting and techniques for their safe and efficacious delivery to the cochlea. Novel biomaterials are enabling high payloads of drugs to be administered to the cochlea with subsequent slow-release properties that are proving to be beneficial for treating hearing loss. In parallel, new gene therapy technologies are addressing the need for cell specificity and high efficacy for the treatment of both genetic and acquired hearing loss with promising reports of hearing recovery. Some biomaterials and cell therapies are being used in conjunction with the cochlear implant ensuring therapeutic benefit to the primary neurons during electrical stimulation. This review will introduce the auditory system, hearing loss and the potential for repair and regeneration in the cochlea. Drug delivery to the cochlea will then be reviewed, with a focus on new biomaterials, gene therapy technologies, cell therapy and the use of the cochlear implant as a vehicle for drug delivery. With the current pre-clinical research effort into therapies for hearing loss, including clinical trials for gene therapy, the future for the treatment for hearing loss is looking bright.
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Affiliation(s)
- Yutian Ma
- Bionics Institute, East Melbourne, Australia; ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Australia; University of Melbourne, Department of Chemical Engineering, Parkville, Victoria, Australia
| | - Andrew K Wise
- Bionics Institute, East Melbourne, Australia; University of Melbourne, Medical Bionics Department, East Melbourne, Australia; University of Melbourne, Department of Surgery - Otolaryngology, East Melbourne, Australia
| | - Robert K Shepherd
- Bionics Institute, East Melbourne, Australia; University of Melbourne, Medical Bionics Department, East Melbourne, Australia; University of Melbourne, Department of Surgery - Otolaryngology, East Melbourne, Australia
| | - Rachael T Richardson
- Bionics Institute, East Melbourne, Australia; University of Melbourne, Medical Bionics Department, East Melbourne, Australia; University of Melbourne, Department of Surgery - Otolaryngology, East Melbourne, Australia.
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20
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McGovern MM, Randle MR, Cuppini CL, Graves KA, Cox BC. Multiple supporting cell subtypes are capable of spontaneous hair cell regeneration in the neonatal mouse cochlea. Development 2019; 146:146/4/dev171009. [PMID: 30770379 DOI: 10.1242/dev.171009] [Citation(s) in RCA: 28] [Impact Index Per Article: 5.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/14/2018] [Accepted: 01/09/2019] [Indexed: 12/20/2022]
Abstract
Supporting cells (SCs) are known to spontaneously regenerate hair cells (HCs) in the neonatal mouse cochlea, yet little is known about the relative contribution of distinct SC subtypes which differ in morphology and function. We have previously shown that HC regeneration is linked to Notch signaling, and some SC subtypes, but not others, lose expression of the Notch effector Hes5 Other work has demonstrated that Lgr5-positive SCs have an increased capacity to regenerate HCs; however, several SC subtypes express Lgr5. To further investigate the source for spontaneous HC regeneration, we used three CreER lines to fate-map distinct groups of SCs during regeneration. Fate-mapping either alone or combined with a mitotic tracer showed that pillar and Deiters' cells contributed more regenerated HCs overall. However, when normalized to the total fate-mapped population, pillar, Deiters', inner phalangeal and border cells had equal capacity to regenerate HCs, and all SC subtypes could divide after HC damage. Investigating the mechanisms that allow individual SC subtypes to regenerate HCs and the postnatal changes that occur in each group during maturation could lead to therapies for hearing loss.
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Affiliation(s)
- Melissa M McGovern
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL 62711, USA
| | - Michelle R Randle
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL 62711, USA
| | - Candice L Cuppini
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL 62711, USA
| | - Kaley A Graves
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL 62711, USA
| | - Brandon C Cox
- Department of Pharmacology, Southern Illinois University School of Medicine, Springfield, IL 62711, USA .,Department of Surgery, Division of Otolaryngology, Southern Illinois University School of Medicine, Springfield, IL 62711, USA
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21
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Atkinson PJ, Kim GS, Cheng AG. Direct cellular reprogramming and inner ear regeneration. Expert Opin Biol Ther 2019; 19:129-139. [PMID: 30584811 DOI: 10.1080/14712598.2019.1564035] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/14/2023]
Abstract
INTRODUCTION Sound is integral to communication and connects us to the world through speech and music. Cochlear hair cells are essential for converting sounds into neural impulses. However, these cells are highly susceptible to damage from an array of factors, resulting in degeneration and ultimately irreversible hearing loss in humans. Since the discovery of hair cell regeneration in birds, there have been tremendous efforts to identify therapies that could promote hair cell regeneration in mammals. AREAS COVERED Here, we will review recent studies describing spontaneous hair cell regeneration and direct cellular reprograming as well as other factors that mediate mammalian hair cell regeneration. EXPERT OPINION Numerous combinatorial approaches have successfully reprogrammed non-sensory supporting cells to form hair cells, albeit with limited efficacy and maturation. Studies on epigenetic regulation and transcriptional network of hair cell progenitors may accelerate discovery of more promising reprogramming regimens.
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Affiliation(s)
- Patrick J Atkinson
- a Department of Otolaryngology-Head and Neck Surgery , Stanford University School of Medicine , Stanford , CA , USA
| | - Grace S Kim
- a Department of Otolaryngology-Head and Neck Surgery , Stanford University School of Medicine , Stanford , CA , USA
| | - Alan G Cheng
- a Department of Otolaryngology-Head and Neck Surgery , Stanford University School of Medicine , Stanford , CA , USA
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22
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Jahan I, Elliott KL, Fritzsch B. Understanding Molecular Evolution and Development of the Organ of Corti Can Provide Clues for Hearing Restoration. Integr Comp Biol 2018; 58:351-365. [PMID: 29718413 PMCID: PMC6104702 DOI: 10.1093/icb/icy019] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Abstract
The mammalian hearing organ is a stereotyped cellular assembly with orderly innervation: two types of spiral ganglion neurons (SGNs) innervate two types of differentially distributed hair cells (HCs). HCs and SGNs evolved from single neurosensory cells through gene multiplication and diversification. Independent regulation of HCs and neuronal differentiation through expression of basic helix-loop-helix transcription factors (bHLH TFs: Atoh1, Neurog1, Neurod1) led to the evolution of vestibular HC assembly and their unique type of innervation. In ancestral mammals, a vestibular organ was transformed into the organ of Corti (OC) containing a single row of inner HC (IHC), three rows of outer HCs (OHCs), several unique supporting cell types, and a peculiar innervation distribution. Restoring the OC following long-term hearing loss is complicated by the fact that the entire organ is replaced by a flat epithelium and requires reconstructing the organ from uniform undifferentiated cell types, recapitulating both evolution and development. Finding the right sequence of gene activation during development that is useful for regeneration could benefit from an understanding of the OC evolution. Toward this end, we report on Foxg1 and Lmx1a mutants that radically alter the OC cell assembly and its innervation when mutated and may have driven the evolutionary reorganization of the basilar papilla into an OC in ancestral Therapsids. Furthermore, genetically manipulating the level of bHLH TFs changes HC type and distribution and allows inference how transformation of HCs might have happened evolutionarily. We report on how bHLH TFs regulate OHC/IHC and how misexpression (Atoh1-Cre; Atoh1f/kiNeurog1) alters HC fate and supporting cell development. Using mice with altered HC types and distribution, we demonstrate innervation changes driven by HC patterning. Using these insights, we speculate on necessary steps needed to convert a random mixture of post-mitotic precursors into the orderly OC through spatially and temporally regulated critical bHLH genes in the context of other TFs to restore normal innervation patterns.
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Affiliation(s)
- Israt Jahan
- Department of Biology, University of Iowa, 129 East Jefferson, Iowa City, IA 52242, USA
| | - Karen L Elliott
- Department of Biology, University of Iowa, 129 East Jefferson, Iowa City, IA 52242, USA
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, 129 East Jefferson, Iowa City, IA 52242, USA
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McPherson DR, Swalla BJ. High Time for Hair Cells: An Introduction to the Symposium on Sensory Hair Cells. Integr Comp Biol 2018; 58:276-281. [PMID: 30137315 DOI: 10.1093/icb/icy070] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Sensory hair cells are highly specialized cells that form the basis for our senses of hearing, orientation to gravity, and perception of linear acceleration (head translation in space) and angular acceleration (head rotation). In many species of fish and aquatic amphibians, hair cells mediate perception of water movement through the lateral line system, and electroreceptors derived from hair cell precursors mediate electric field detection. In tunicates, cells of the mechanosensory coronal organ on the incurrent siphon meet the structural, functional, and developmental criteria to be described as hair cells, and they function to deflect large particles from entering the animal. The past two decades have witnessed significant breakthroughs in our understanding of hair cell biology and how their specialized structures influence their functions. This symposium combines the approaches of developmental biology, evolutionary biology, and physiology to share the gains of recent research in understanding hair cell function in different model systems. We brought together researchers working on sensory hair cells in organisms spanning the chordates in order to examine the depth and breadth of hair cell evolution. It is clear that these specialized cells serve a range of functions in different animals, due to evolutionary tinkering with a basic specialized cell type. This collection of papers will serve to mark the progress that has been made in this field and also stimulate the next wave of progress in this exciting field.
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Affiliation(s)
| | - Billie J Swalla
- Friday Harbor Laboratories, Friday Harbor, 620 University Road, WA 98250, USA
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McGovern MM, Zhou L, Randle MR, Cox BC. Spontaneous Hair Cell Regeneration Is Prevented by Increased Notch Signaling in Supporting Cells. Front Cell Neurosci 2018; 12:120. [PMID: 29780306 PMCID: PMC5945818 DOI: 10.3389/fncel.2018.00120] [Citation(s) in RCA: 16] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2018] [Accepted: 04/13/2018] [Indexed: 11/13/2022] Open
Abstract
During embryonic development, differentiation of cochlear progenitor cells into hair cells (HCs) or supporting cells (SCs) is partially controlled through Notch signaling. Many studies have shown that inhibition of Notch signaling allows SCs to convert into HCs in both normal and drug damaged neonatal mouse cochleae. This mechanism is also implicated during HC regeneration in non-mammalian vertebrates; however, the mechanism of spontaneous HC regeneration in the neonatal mouse cochlea is less understood. While inhibition of Notch signaling can force SCs to convert into HCs and increase the number of regenerated HCs, it is currently unknown whether this pathway is involved in spontaneous HC regeneration observed in vivo. Therefore, we investigated the role of Notch signaling during the spontaneous HC regeneration process using Atoh1-CreERTM::Rosa26loxP-stop-loxP-DTA/+ mice injected with tamoxifen at postnatal day (P) 0 and P1 to ablate HCs and stimulate spontaneous HC regeneration. Expression changes of genes in the Notch pathway were measured using immunostaining and in situ hybridization, with most changes observed in the apical one-third of the cochlea where the majority of HC regeneration occurs. Expression of the Notch target genes Hes1, Hes5, Hey1, HeyL, and Jagged1 were decreased. To investigate whether reduction of Notch signaling is involved in the spontaneous HC regeneration process, we overexpressed the Notch1 intracellular fragment (N1ICD) in cochlear SCs and other non-sensory epithelial cells in the context of HC damage. Specifically, Atoh1-CreERTM::Rosa26loxP-stop-loxP-DTA/+::Sox10rtTA::TetO-LacZ::TetO-N1ICD mice were injected with tamoxifen at P0/P1 to stimulate spontaneous HC regeneration and given doxycycline from P0-P7 to induce expression of N1ICD as well as LacZ for fate-mapping. We observed a 92% reduction in the number of fate-mapped regenerated HCs in mice with N1ICD overexpression compared to controls with HC damage but no manipulation of Notch signaling. Therefore, we conclude that increased Notch signaling prevents spontaneous HC regeneration from occurring in the neonatal mouse cochlea. Understanding which components of the Notch pathway regulates regenerative plasticity in the neonatal mouse cochlea will inform investigations focused on stimulating HC regeneration in mature cochlea and eventually in humans to treat hearing loss.
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Affiliation(s)
- Melissa M. McGovern
- Department of Pharmacology, School of Medicine, Southern Illinois University, Springfield, IL, United States
| | - Luyi Zhou
- Department of Pharmacology, School of Medicine, Southern Illinois University, Springfield, IL, United States
| | - Michelle R. Randle
- Department of Pharmacology, School of Medicine, Southern Illinois University, Springfield, IL, United States
| | - Brandon C. Cox
- Department of Pharmacology, School of Medicine, Southern Illinois University, Springfield, IL, United States
- Department of Surgery, Division of Otolaryngology, School of Medicine, Southern Illinois University, Springfield, IL, United States
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Cytoskeletal Stability in the Auditory Organ In Vivo: RhoA Is Dispensable for Wound Healing but Essential for Hair Cell Development. eNeuro 2017; 4:eN-NWR-0149-17. [PMID: 28929130 PMCID: PMC5602105 DOI: 10.1523/eneuro.0149-17.2017] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2017] [Revised: 08/24/2017] [Accepted: 08/28/2017] [Indexed: 01/03/2023] Open
Abstract
Wound healing in the inner ear sensory epithelia is performed by the apical domains of supporting cells (SCs). Junctional F-actin belts of SCs are thin during development but become exceptionally thick during maturation. The functional significance of the thick belts is not fully understood. We have studied the role of F-actin belts during wound healing in the developing and adult cochlea of mice in vivo. We show that the thick belts serve as intracellular scaffolds that preserve the positions of surviving cells in the cochlear sensory epithelium. Junctions associated with the thick F-actin belts did not readily disassemble during wound healing. To compensate for this, basolateral membranes of SCs participated in the closure of surface breach. Because not only neighboring but also distant SCs contributed to wound healing by basolateral protrusions, this event appears to be triggered by contact-independent diffusible signals. In the search for regulators of wound healing, we inactivated RhoA in SCs, which, however, did not limit wound healing. RhoA inactivation in developing outer hair cells (OHCs) caused myosin II delocalization from the perijunctional domain and apical cell-surface enlargement. These abnormalities led to the extrusion of OHCs from the epithelium. These results demonstrate the importance of stability of the apical domain, both in wound repair by SCs and in development of OHCs, and that only this latter function is regulated by RhoA. Because the correct cytoarchitecture of the cochlear sensory epithelium is required for normal hearing, the stability of cell apices should be maintained in regenerative and protective interventions.
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Wang GP, Basu I, Beyer LA, Wong HT, Swiderski DL, Gong SS, Raphael Y. Severe streptomycin ototoxicity in the mouse utricle leads to a flat epithelium but the peripheral neural degeneration is delayed. Hear Res 2017; 355:33-41. [PMID: 28931463 DOI: 10.1016/j.heares.2017.09.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/15/2016] [Revised: 06/21/2017] [Accepted: 09/08/2017] [Indexed: 01/15/2023]
Abstract
The damaged vestibular sensory epithelium of mammals has a limited capacity for spontaneous hair cell regeneration, which largely depends on the transdifferentiation of surviving supporting cells. Little is known about the response of vestibular supporting cells to a severe insult. In the present study, we evaluated the impact of a severe ototoxic insult on the histology of utricular supporting cells and the changes in innervation that ensued. We infused a high dose of streptomycin into the mouse posterior semicircular canal to induce a severe lesion in the utricle. Both scanning electron microscopy and light microscopy of plastic sections showed replacement of the normal cytoarchitecture of the epithelial layer with a flat layer of cells in most of the samples. Immunofluorescence staining showed numerous cells in the severely damaged epithelial layer that were negative for hair cell and supporting cell markers. Nerve fibers under the flat epithelium had high density at the 1 month time point but very low density by 3 months. Similarly, the number of vestibular ganglion neurons was unchanged at 1 month after the lesion, but was significantly lower at 3 months. We therefore determined that the mouse utricular epithelium turns into a flat epithelium after a severe lesion, but the degeneration of neural components is slow, suggesting that treatments to restore balance by hair cell regeneration, stem cell therapy or vestibular prosthesis implantation will likely benefit from the short term preservation of the neural substrate.
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Affiliation(s)
- Guo-Peng Wang
- Department of Otolaryngology - Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, 100050, China; Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI 48109, USA
| | - Ishani Basu
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI 48109, USA
| | - Lisa A Beyer
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI 48109, USA
| | - Hiu Tung Wong
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI 48109, USA
| | - Donald L Swiderski
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI 48109, USA
| | - Shu-Sheng Gong
- Department of Otolaryngology - Head and Neck Surgery, Beijing Friendship Hospital, Capital Medical University, Beijing, 100050, China
| | - Yehoash Raphael
- Kresge Hearing Research Institute, Department of Otolaryngology - Head and Neck Surgery, University of Michigan, Ann Arbor, MI 48109, USA.
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27
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Liu W, Li H, Edin F, Brännström J, Glueckert R, Schrott-Fischer A, Molnar M, Pacholsky D, Pfaller K, Rask-Andersen H. Molecular composition and distribution of gap junctions in the sensory epithelium of the human cochlea-a super-resolution structured illumination microscopy (SR-SIM) study. Ups J Med Sci 2017; 122:160-170. [PMID: 28513246 PMCID: PMC5649321 DOI: 10.1080/03009734.2017.1322645] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/29/2022] Open
Abstract
BACKGROUND Mutations in the GJB2 gene, which encodes the Connexin26 (Cx26) protein, are the most common cause of childhood hearing loss in American and European populations. The cochlea contains a gap junction (GJ) network in the sensory epithelium and two connective tissue networks in the lateral wall and spiral limbus. The syncytia contain the GJ proteins beta 2 (GJB2/Cx26) and beta 6 (GJB6/Cx30). Our knowledge of their expression in humans is insufficient due to the limited availability of tissue. Here, we sought to establish the molecular arrangement of GJs in the epithelial network of the human cochlea using surgically obtained samples. METHODS We analyzed Cx26 and Cx30 expression in GJ networks in well-preserved adult human auditory sensory epithelium using confocal, electron, and super-resolution structured illumination microscopy (SR-SIM). RESULTS Cx30 plaques (<5 μm) dominated, while Cx26 plaques were subtle and appeared as 'mini-junctions' (2-300 nm). 3-D volume rendering of Z-stacks and orthogonal projections from single optical sections suggested that the GJs are homomeric/homotypic and consist of assemblies of identical GJs composed of either Cx26 or Cx30. Occasionally, the two protein types were co-expressed, suggesting functional cooperation. CONCLUSIONS Establishing the molecular composition and distribution of the GJ networks in the human cochlea may increase our understanding of the pathophysiology of Cx-related hearing loss. This information may also assist in developing future strategies to treat genetic hearing loss.
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Affiliation(s)
- Wei Liu
- Department of Surgical Sciences, Head and Neck Surgery, Section of Otolaryngology, Department of Otolaryngology, Uppsala University Hospital, Uppsala, Sweden;
| | - Hao Li
- Department of Surgical Sciences, Head and Neck Surgery, Section of Otolaryngology, Department of Otolaryngology, Uppsala University Hospital, Uppsala, Sweden;
| | - Fredrik Edin
- Department of Surgical Sciences, Head and Neck Surgery, Section of Otolaryngology, Department of Otolaryngology, Uppsala University Hospital, Uppsala, Sweden;
| | - Johan Brännström
- Department of Immunology, Genetics and Pathology, The Rudbeck Laboratory, Uppsala University, Uppsala, Sweden;
| | - Rudolf Glueckert
- Department of Otolaryngology, Medical University of Innsbruck, Innsbruck, Austria;
| | | | - Matyas Molnar
- Science for Life Laboratory, BioVis Facility, Uppsala University, Uppsala, Sweden;
| | - Dirk Pacholsky
- Science for Life Laboratory, BioVis Facility, Uppsala University, Uppsala, Sweden;
| | - Kristian Pfaller
- Department of Histology and Molecular Cell Biology, Institute of Anatomy and Histology, Medical University of Innsbruck, Innsbruck, Austria
| | - Helge Rask-Andersen
- Department of Surgical Sciences, Head and Neck Surgery, Section of Otolaryngology, Department of Otolaryngology, Uppsala University Hospital, Uppsala, Sweden;
- CONTACT Helge Rask-Andersen Department of Surgical Sciences, Head and Neck Surgery, Section of Otolaryngology, Department of Otolaryngology, Uppsala University Hospital, SE-751 85, Uppsala, Sweden
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28
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Ladrech S, Eybalin M, Puel JL, Lenoir M. Epithelial-mesenchymal transition, and collective and individual cell migration regulate epithelial changes in the amikacin-damaged organ of Corti. Histochem Cell Biol 2017; 148:129-142. [PMID: 28365859 DOI: 10.1007/s00418-017-1548-6] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 02/03/2017] [Indexed: 12/23/2022]
Abstract
Characterizing the microenvironment of a damaged organ of Corti and identifying the basic mechanisms involved in subsequent epithelial reorganization are critical for improving the outcome of clinical therapies. In this context, we studied the expression of a variety of cell markers related to cell shape, cell adhesion and cell plasticity in the rat organ of Corti poisoned with amikacin. Our results indicate that, after severe outer hair cell losses, the cytoarchitectural reorganization of the organ of Corti implicates epithelial-mesenchymal transition mechanisms and involves both collective and individual cell migratory processes. The results also suggest that both root cells and infiltrated fibroblasts participate in the homeostasis of the damaged epithelium, and that the flat epithelium that may emerge offers biological opportunities for late regenerative therapies.
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Affiliation(s)
- Sabine Ladrech
- INSERM U1051, Institut des Neurosciences de Montpellier, Hôpital Saint Eloi, 80 rue Augustin Fliche, 34091, Montpellier Cedex 5, France.,University of Montpellier, Montpellier, France
| | - Michel Eybalin
- INSERM U1051, Institut des Neurosciences de Montpellier, Hôpital Saint Eloi, 80 rue Augustin Fliche, 34091, Montpellier Cedex 5, France.,University of Montpellier, Montpellier, France
| | - Jean-Luc Puel
- INSERM U1051, Institut des Neurosciences de Montpellier, Hôpital Saint Eloi, 80 rue Augustin Fliche, 34091, Montpellier Cedex 5, France.,University of Montpellier, Montpellier, France
| | - Marc Lenoir
- INSERM U1051, Institut des Neurosciences de Montpellier, Hôpital Saint Eloi, 80 rue Augustin Fliche, 34091, Montpellier Cedex 5, France. .,University of Montpellier, Montpellier, France.
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29
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Hair Cell Loss, Spiral Ganglion Degeneration, and Progressive Sensorineural Hearing Loss in Mice with Targeted Deletion of Slc44a2/Ctl2. J Assoc Res Otolaryngol 2016; 16:695-712. [PMID: 26463873 PMCID: PMC4636594 DOI: 10.1007/s10162-015-0547-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/09/2015] [Accepted: 10/01/2015] [Indexed: 11/05/2022] Open
Abstract
SLC44A2 (solute carrier 44a2), also known as CTL2 (choline transporter-like protein 2), is expressed in many supporting cell types in the cochlea and is implicated in hair cell survival and antibody-induced hearing loss. In mice with the mixed C57BL/6-129 background, homozygous deletion of Slc44a2 exons 3–10 (Slc44a2Δ/Δ) resulted in high-frequency hearing loss and hair cell death. To reduce effects associated with age-related hearing loss (ARHL) in these strains, mice carrying the Slc44a2Δ allele were backcrossed to the ARHL-resistant FVB/NJ strain and evaluated after backcross seven (N7) (99 % FVB). Slc44a2Δ/Δ mice produced abnormally spliced Slc44a2 transcripts that contain a frameshift and premature stop codons. Neither full-length SLC44A2 nor a putative truncated protein could be detected in Slc44a2Δ/Δ mice, suggesting a likely null allele. Auditory brain stem responses (ABRs) of mice carrying the Slc44a2Δ allele on an FVB/NJ genetic background were tested longitudinally between the ages of 2 and 10 months. By 6 months of age, Slc44a2Δ/Δ mice exhibited hearing loss at 32 kHz, but at 12 and 24 kHz had sound thresholds similar to those of wild-type Slc44a2+/+ and heterozygous +/Slc44a2Δ mice. After 6 months of age, Slc44a2Δ/Δ mutants exhibited progressive hearing loss at all frequencies and +/Slc44a2Δ mice exhibited moderate threshold elevations at high frequency. Histologic evaluation of Slc44a2Δ/Δ mice revealed extensive hair cell and spiral ganglion cell loss, especially in the basal turn of the cochlea. We conclude that Slc44a2 function is required for long-term hair cell survival and maintenance of hearing.
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30
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Han C, Linser P, Park HJ, Kim MJ, White K, Vann JM, Ding D, Prolla TA, Someya S. Sirt1 deficiency protects cochlear cells and delays the early onset of age-related hearing loss in C57BL/6 mice. Neurobiol Aging 2016; 43:58-71. [PMID: 27255815 DOI: 10.1016/j.neurobiolaging.2016.03.023] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 02/29/2016] [Accepted: 03/22/2016] [Indexed: 10/22/2022]
Abstract
Hearing gradually declines with age in both animals and humans, and this condition is known as age-related hearing loss (AHL). Here, we investigated the effects of deficiency of Sirt1, a member of the mammalian sirtuin family, on age-related cochlear pathology and associated hearing loss in C57BL/6 mice, a mouse model of early-onset AHL. Sirt1 deficiency reduced age-related oxidative damage of cochlear hair cells and spiral ganglion neurons and delayed the early onset of AHL. In cultured mouse inner ear cell lines, Sirt1 knockdown increased cell viability under oxidative stress conditions, induced nuclear translocation of Foxo3a, and increased acetylation status of Foxo3a. This resulted in increased activity of the antioxidant enzyme catalase. In young wild-type mice, both Sirt1 and Foxo3a proteins resided in the cytoplasm of the supporting cells within the organ of Corti of the cochlea. Therefore, our findings suggest that SIRT1 promotes early-onset AHL through suppressing FOXO3a-mediated oxidative stress resistance in the cochlea of C57BL/6 mice.
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Affiliation(s)
- Chul Han
- Department of Aging and Geriatric Research, University of Florida, Gainesville, FL, USA
| | - Paul Linser
- Whitney Laboratory, University of Florida, St Augustine, FL, USA
| | - Hyo-Jin Park
- Department of Neurology, University of Florida, Gainesville, FL, USA
| | - Mi-Jung Kim
- Department of Aging and Geriatric Research, University of Florida, Gainesville, FL, USA
| | - Karessa White
- Department of Aging and Geriatric Research, University of Florida, Gainesville, FL, USA
| | - James M Vann
- Department of Genetics, University of Wisconsin, Madison, WI, USA; Department of Medical Genetics, University of Wisconsin, Madison, WI, USA
| | - Dalian Ding
- Center for Hearing and Deafness, State University of New York at Buffalo, NY, USA
| | - Tomas A Prolla
- Department of Genetics, University of Wisconsin, Madison, WI, USA; Department of Medical Genetics, University of Wisconsin, Madison, WI, USA
| | - Shinichi Someya
- Department of Aging and Geriatric Research, University of Florida, Gainesville, FL, USA.
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Parker A, Cross SH, Jackson IJ, Hardisty-Hughes R, Morse S, Nicholson G, Coghill E, Bowl MR, Brown SDM. The goya mouse mutant reveals distinct newly identified roles for MAP3K1 in the development and survival of cochlear sensory hair cells. Dis Model Mech 2015; 8:1555-68. [PMID: 26542706 PMCID: PMC4728324 DOI: 10.1242/dmm.023176] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2015] [Accepted: 10/30/2015] [Indexed: 01/10/2023] Open
Abstract
Mitogen-activated protein kinase, MAP3K1, plays an important role in a number of cellular processes, including epithelial migration during eye organogenesis. In addition, studies in keratinocytes indicate that MAP3K1 signalling through JNK is important for actin stress fibre formation and cell migration. However, MAP3K1 can also act independently of JNK in the regulation of cell proliferation and apoptosis. We have identified a mouse mutant, goya, which exhibits the eyes-open-at-birth and microphthalmia phenotypes. In addition, these mice also have hearing loss. The goya mice carry a splice site mutation in the Map3k1 gene. We show that goya and kinase-deficient Map3k1 homozygotes initially develop supernumerary cochlear outer hair cells (OHCs) that subsequently degenerate, and a progressive profound hearing loss is observed by 9 weeks of age. Heterozygote mice also develop supernumerary OHCs, but no cellular degeneration or hearing loss is observed. MAP3K1 is expressed in a number of inner-ear cell types, including outer and inner hair cells, stria vascularis and spiral ganglion. Investigation of targets downstream of MAP3K1 identified an increase in p38 phosphorylation (Thr180/Tyr182) in multiple cochlear tissues. We also show that the extra OHCs do not arise from aberrant control of proliferation via p27KIP1. The identification of the goya mutant reveals a signalling molecule involved with hair-cell development and survival. Mammalian hair cells do not have the ability to regenerate after damage, which can lead to irreversible sensorineural hearing loss. Given the observed goya phenotype, and the many diverse cellular processes that MAP3K1 is known to act upon, further investigation of this model might help to elaborate upon the mechanisms underlying sensory hair cell specification, and pathways important for their survival. In addition, MAP3K1 is revealed as a new candidate gene for human sensorineural hearing loss. Summary: The ENU-derived mouse mutant goya, reveals, for the first time, multiple roles of MAP3K1 in cochlear development and correct auditory function.
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Affiliation(s)
- Andrew Parker
- MRC Mammalian Genetics Unit, MRC Harwell, Oxford, OX11 0RD, UK
| | - Sally H Cross
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Edinburgh, EH4 2XU, UK
| | - Ian J Jackson
- MRC Human Genetics Unit, MRC IGMM, University of Edinburgh, Edinburgh, EH4 2XU, UK The Roslin Institute, University of Edinburgh, Easter Bush, EH25 9RG, UK
| | | | - Susan Morse
- MRC Mammalian Genetics Unit, MRC Harwell, Oxford, OX11 0RD, UK
| | - George Nicholson
- MRC Mammalian Genetics Unit, MRC Harwell, Oxford, OX11 0RD, UK Department of Statistics, University of Oxford, Oxford, OX1 3TG, UK
| | - Emma Coghill
- MRC Mammalian Genetics Unit, MRC Harwell, Oxford, OX11 0RD, UK
| | - Michael R Bowl
- MRC Mammalian Genetics Unit, MRC Harwell, Oxford, OX11 0RD, UK
| | - Steve D M Brown
- MRC Mammalian Genetics Unit, MRC Harwell, Oxford, OX11 0RD, UK
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32
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Jahan I, Pan N, Elliott KL, Fritzsch B. The quest for restoring hearing: Understanding ear development more completely. Bioessays 2015. [PMID: 26208302 DOI: 10.1002/bies.201500044] [Citation(s) in RCA: 36] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Neurosensory hearing loss is a growing problem of super-aged societies. Cochlear implants can restore some hearing, but rebuilding a lost hearing organ would be superior. Research has discovered many cellular and molecular steps to develop a hearing organ but translating those insights into hearing organ restoration remains unclear. For example, we cannot make various hair cell types and arrange them into their specific patterns surrounded by the right type of supporting cells in the right numbers. Our overview of the topologically highly organized and functionally diversified cellular mosaic of the mammalian hearing organ highlights what is known and unknown about its development. Following this analysis, we suggest critical steps to guide future attempts toward restoration of a functional organ of Corti. We argue that generating mutant mouse lines that mimic human pathology to fine-tune attempts toward long-term functional restoration are needed to go beyond the hope generated by restoring single hair cells in postnatal sensory epithelia.
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Affiliation(s)
- Israt Jahan
- Department of Biology, CLAS, University of Iowa, Iowa City, IA, USA
| | - Ning Pan
- Department of Biology, CLAS, University of Iowa, Iowa City, IA, USA
| | - Karen L Elliott
- Department of Biology, CLAS, University of Iowa, Iowa City, IA, USA
| | - Bernd Fritzsch
- Department of Biology, CLAS, University of Iowa, Iowa City, IA, USA
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33
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Taylor RR, Jagger DJ, Saeed SR, Axon P, Donnelly N, Tysome J, Moffatt D, Irving R, Monksfield P, Coulson C, Freeman SR, Lloyd SK, Forge A. Characterizing human vestibular sensory epithelia for experimental studies: new hair bundles on old tissue and implications for therapeutic interventions in ageing. Neurobiol Aging 2015; 36:2068-84. [PMID: 25818177 PMCID: PMC4436436 DOI: 10.1016/j.neurobiolaging.2015.02.013] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2014] [Revised: 02/09/2015] [Accepted: 02/11/2015] [Indexed: 12/19/2022]
Abstract
Balance disequilibrium is a significant contributor to falls in the elderly. The most common cause of balance dysfunction is loss of sensory cells from the vestibular sensory epithelia of the inner ear. However, inaccessibility of inner ear tissue in humans severely restricts possibilities for experimental manipulation to develop therapies to ameliorate this loss. We provide a structural and functional analysis of human vestibular sensory epithelia harvested at trans-labyrinthine surgery. We demonstrate the viability of the tissue and labeling with specific markers of hair cell function and of ion homeostasis in the epithelium. Samples obtained from the oldest patients revealed a significant loss of hair cells across the tissue surface, but we found immature hair bundles present in epithelia harvested from patients >60 years of age. These results suggest that the environment of the human vestibular sensory epithelium could be responsive to stimulation of developmental pathways to enhance hair cell regeneration, as has been demonstrated successfully in the vestibular organs of adult mice.
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Affiliation(s)
| | | | - Shakeel R Saeed
- UCL Ear Institute, London, UK; Royal National Throat Nose and Ear Hospital, UCLH NHS Foundation Trust, London, UK
| | - Patrick Axon
- Addenbrooke's Hospital, Cambridge University NHS Foundation Trust, Cambridge, UK
| | - Neil Donnelly
- Addenbrooke's Hospital, Cambridge University NHS Foundation Trust, Cambridge, UK
| | - James Tysome
- Addenbrooke's Hospital, Cambridge University NHS Foundation Trust, Cambridge, UK
| | - David Moffatt
- Addenbrooke's Hospital, Cambridge University NHS Foundation Trust, Cambridge, UK
| | - Richard Irving
- Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Medical Centre, Birmingham, UK
| | - Peter Monksfield
- Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Medical Centre, Birmingham, UK
| | - Chris Coulson
- Queen Elizabeth Hospital, University Hospitals Birmingham NHS Foundation Trust, Queen Elizabeth Medical Centre, Birmingham, UK
| | - Simon R Freeman
- Manchester Royal Infirmary, Central Manchester University Hospitals NHS Trust, Manchester, UK; Salford Royal Infirmary, Salford Royal NHS Foundation Trust, Salford, UK
| | - Simon K Lloyd
- Manchester Royal Infirmary, Central Manchester University Hospitals NHS Trust, Manchester, UK; Salford Royal Infirmary, Salford Royal NHS Foundation Trust, Salford, UK
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34
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Kersigo J, Fritzsch B. Inner ear hair cells deteriorate in mice engineered to have no or diminished innervation. Front Aging Neurosci 2015; 7:33. [PMID: 25852547 PMCID: PMC4364252 DOI: 10.3389/fnagi.2015.00033] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/19/2015] [Accepted: 02/28/2015] [Indexed: 12/14/2022] Open
Abstract
The innervation of the inner ear critically depends on the two neurotrophins Ntf3 and Bdnf. In contrast to this molecularly well-established dependency, evidence regarding the need of innervation for long-term maintenance of inner ear hair cells is inconclusive, due to experimental variability. Mutant mice that lack both neurotrophins could shed light on the long-term consequences of innervation loss on hair cells without introducing experimental variability, but do not survive after birth. Mutant mice with conditional deletion of both neurotrophins lose almost all innervation by postnatal day 10 and show an initially normal development of hair cells by this stage. No innervation remains after 3 weeks and complete loss of all innervation results in near complete loss of outer and many inner hair cells of the organ of Corti within 4 months. Mutants that retain one allele of either neurotrophin have only partial loss of innervation of the organ of Corti and show a longer viability of cochlear hair cells with more profound loss of inner hair cells. By 10 months, hair cells disappear with a base to apex progression, proportional to the residual density of innervation and similar to carboplatin ototoxicity. Similar to reports of hair cell loss after aminoglycoside treatment, blobbing of stereocilia of apparently dying hair cells protrude into the cochlear duct. Denervation of vestibular sensory epithelia for several months also resulted in variable results, ranging from unusual hair cells resembling the aberrations found in the organ of Corti, to near normal hair cells in the canal cristae. Fusion and/or resorption of stereocilia and loss of hair cells follows a pattern reminiscent of Myo6 and Cdc42 null mice. Our data support a role of innervation for long-term maintenance but with a remarkable local variation that needs to be taken into account when attempting regeneration of the organ of Corti.
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Affiliation(s)
| | - Bernd Fritzsch
- Department of Biology, University of IowaIowa City, IA, USA
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Abbas L, Rivolta MN. Aminoglycoside ototoxicity and hair cell ablation in the adult gerbil: A simple model to study hair cell loss and regeneration. Hear Res 2015; 325:12-26. [PMID: 25783988 PMCID: PMC4441107 DOI: 10.1016/j.heares.2015.03.002] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 02/27/2015] [Accepted: 03/03/2015] [Indexed: 11/19/2022]
Abstract
The Mongolian gerbil, Meriones unguiculatus, has been widely employed as a model for studies of the inner ear. In spite of its established use for auditory research, no robust protocols to induce ototoxic hair cell damage have been developed for this species. In this paper, we demonstrate the development of an aminoglycoside-induced model of hair cell loss, using kanamycin potentiated by the loop diuretic furosemide. Interestingly, we show that the gerbil is relatively insensitive to gentamicin compared to kanamycin, and that bumetanide is ineffective in potentiating the ototoxicity of the drug. We also examine the pathology of the spiral ganglion after chronic, long-term hair cell damage. Remarkably, there is little or no neuronal loss following the ototoxic insult, even at 8 months post-damage. This is similar to the situation often seen in the human, where functioning neurons can persist even decades after hair cell loss, contrasting with the rapid, secondary degeneration found in rats, mice and other small mammals. We propose that the combination of these factors makes the gerbil a good model for ototoxic damage by induced hair cell loss.
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Affiliation(s)
- Leila Abbas
- Centre for Stem Cell Biology and Department of Biomedical Sciences, University of Sheffield, Sheffield S10 2TN, United Kingdom
| | - Marcelo N Rivolta
- Centre for Stem Cell Biology and Department of Biomedical Sciences, University of Sheffield, Sheffield S10 2TN, United Kingdom.
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Jahan I, Pan N, Fritzsch B. Opportunities and limits of the one gene approach: the ability of Atoh1 to differentiate and maintain hair cells depends on the molecular context. Front Cell Neurosci 2015; 9:26. [PMID: 25698932 PMCID: PMC4318345 DOI: 10.3389/fncel.2015.00026] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 01/14/2015] [Indexed: 02/03/2023] Open
Abstract
Atoh1 (Math1) was the first gene discovered in ear development that showed no hair cell (HC) differentiation when absent and could induce HC differentiation when misexpressed. These data implied that Atoh1 was both necessary and sufficient for hair cell development. However, other gene mutations also result in loss of initially forming HCs, notably null mutants for Pou4f3, Barhl1, and Gfi1. HC development and maintenance also depend on the expression of other genes (Sox2, Eya1, Gata3, Pax2) and several genes have been identified that can induce HCs when misexpressed (Jag1) or knocked out (Lmo4). In the ear Atoh1 is not only expressed in HCs but also in some supporting cells and neurons that do not differentiate into HCs. Simple removal of one gene, Neurod1, can de-repress Atoh1 and turns those neurons into HCs suggesting that Neurod1 blocks Atoh1 function in neurons. Atoh1 expression in inner pillar cells may also be blocked by too many Hes/Hey factors but conversion into HCs has only partially been achieved through Hes/Hey removal. Detailed analysis of cell cycle exit confirmed an apex to base cell cycle exit progression of HCs of the organ of Corti. In contrast, Atoh1 expression progresses from the base toward the apex with a variable delay relative to the cell cycle exit. Most HCs exit the cell cycle and are thus defined as precursors before Atoh1 is expressed. Atoh1 is a potent differentiation factor but can differentiate and maintain HCs only in the ear and when other factors are co-expressed. Upstream factors are essential to regulate Atoh1 level of expression duration while downstream, co-activated by other factors, will define the context of Atoh1 action. We suggest that these insights need to be taken into consideration and approaches beyond the simple Atoh1 expression need to be designed able to generate the radial and longitudinal variations in hair cell types for normal function of the organ of Corti.
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Affiliation(s)
- Israt Jahan
- Department of Biology, University of Iowa Iowa City, IA, USA
| | - Ning Pan
- Department of Biology, University of Iowa Iowa City, IA, USA
| | - Bernd Fritzsch
- Department of Biology, University of Iowa Iowa City, IA, USA
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Richardson RT, Atkinson PJ. Atoh1 gene therapy in the cochlea for hair cell regeneration. Expert Opin Biol Ther 2015; 15:417-30. [DOI: 10.1517/14712598.2015.1009889] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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Abstract
The loss of auditory hair cells triggers repair responses within the population of nonsensory supporting cells. When hair cells are irreversibly lost from the mammalian cochlea, supporting cells expand to fill the resulting lesions in the sensory epithelium, an initial repair process that is dependent on gap junctional intercellular communication (GJIC). In the chicken cochlea (the basilar papilla or BP), dying hair cells are extruded from the epithelium and supporting cells expand to fill the lesions and then replace hair cells via mitotic and/or conversion mechanisms. Here, we investigated the involvement of GJIC in the initial epithelial repair process in the aminoglycoside-damaged BP. Gentamicin-induced hair cell loss was associated with a decrease of chicken connexin43 (cCx43) immunofluorescence, yet cCx30-labeled gap junction plaques remained. Fluorescence recovery after photobleaching experiments confirmed that the GJIC remained robust in gentamicin-damaged explants, but regionally asymmetric coupling was no longer evident. Dye injections in slice preparations from undamaged BP explants identified cell types with characteristic morphologies along the neural-abneural axis, but these were electrophysiologically indistinct. In gentamicin-damaged BP, supporting cells expanded to fill space formerly occupied by hair cells and displayed more variable electrophysiological phenotypes. When GJIC was inhibited during the aminoglycoside damage paradigm, the epithelial repair response halted. Dying hair cells were retained within the sensory epithelium and supporting cells remained unexpanded. These observations suggest that repair of the auditory epithelium shares common mechanisms across vertebrate species and emphasize the importance of functional gap junctions in maintaining a homeostatic environment permissive for subsequent hair cell regeneration.
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Postnatal expression of neurotrophic factors accessible to spiral ganglion neurons in the auditory system of adult hearing and deafened rats. J Neurosci 2014; 34:13110-26. [PMID: 25253857 DOI: 10.1523/jneurosci.1014-14.2014] [Citation(s) in RCA: 36] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023] Open
Abstract
Spiral ganglion neurons (SGNs) receive input from cochlear hair cells and project from the cochlea to the cochlear nucleus. After destruction of hair cells with aminoglycoside antibiotics or noise, SGNs gradually die. It has been assumed that SGN death is attributable to loss of neurotrophic factors (NTFs) derived from hair cells or supporting cells in the organ of Corti (OC). We used quantitative PCR (qPCR) to assay NTF expression-neurotrophin-3 (NT-3), BDNF, GDNF, neurturin, artemin, and CNTF-in the OC and cochlear nucleus at various ages from postnatal day 0 (P0) to P90 in control hearing and neonatally deafened rats. NT-3, neurturin, and CNTF were most abundant in the postnatal hearing OC; CNTF and neurturin most abundant in the cochlear nucleus. In the OC, NT-3 and CNTF showed a postnatal increase in expression approximately concomitant with hearing onset. In rats deafened by daily kanamycin injections (from P8 to P16), surviving inner hair cells were evident at P16 but absent by P19, with most postsynaptic boutons lost before P16. NT-3 and CNTF, which normally increase postnatally, had significantly reduced expression in the OC of deafened rats, although CNTF was expressed throughout the time that SGNs were dying. In contrast, neurturin expression was constant, unaffected by deafening or by age. CNTF and neurturin expression in the cochlear nucleus was unaffected by deafening or age. Thus, NTFs other than NT-3 are available to SGNs even as they are dying after deafening, apparently conflicting with the hypothesis that SGN death is attributable to lack of NTFs.
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Spontaneous regeneration of cochlear supporting cells after neonatal ablation ensures hearing in the adult mouse. Proc Natl Acad Sci U S A 2014; 111:16919-24. [PMID: 25385613 DOI: 10.1073/pnas.1408064111] [Citation(s) in RCA: 54] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
Supporting cells in the cochlea play critical roles in the development, maintenance, and function of sensory hair cells and auditory neurons. Although the loss of hair cells or auditory neurons results in sensorineural hearing loss, the consequence of supporting cell loss on auditory function is largely unknown. In this study, we specifically ablated inner border cells (IBCs) and inner phalangeal cells (IPhCs), the two types of supporting cells surrounding inner hair cells (IHCs) in mice in vivo. We demonstrate that the organ of Corti has the intrinsic capacity to replenish IBCs/IPhCs effectively during early postnatal development. Repopulation depends on the presence of hair cells and cells within the greater epithelial ridge and is independent of cell proliferation. This plastic response in the neonatal cochlea preserves neuronal survival, afferent innervation, and hearing sensitivity in adult mice. In contrast, the capacity for IBC/IPhC regeneration is lost in the mature organ of Corti, and consequently IHC survival and hearing sensitivity are impaired significantly, demonstrating that there is a critical period for the regeneration of cochlear supporting cells. Our findings indicate that the quiescent neonatal organ of Corti can replenish specific supporting cells completely after loss in vivo to guarantee mature hearing function.
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Jagger DJ, Forge A. Connexins and gap junctions in the inner ear--it's not just about K⁺ recycling. Cell Tissue Res 2014; 360:633-44. [PMID: 25381570 PMCID: PMC4452565 DOI: 10.1007/s00441-014-2029-z] [Citation(s) in RCA: 71] [Impact Index Per Article: 7.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Accepted: 10/06/2014] [Indexed: 12/19/2022]
Abstract
Normal development, function and repair of the sensory epithelia in the inner ear are all dependent on gap junctional intercellular communication. Mutations in the connexin genes GJB2 and GJB6 (encoding CX26 and CX30) result in syndromic and non-syndromic deafness via various mechanisms. Clinical vestibular defects, however, are harder to connect with connexin dysfunction. Cx26 and Cx30 proteins are widely expressed in the epithelial and connective tissues of the cochlea, where they may form homomeric or heteromeric gap junction channels in a cell-specific and spatiotemporally complex fashion. Despite the study of mutant channels and animal models for both recessive and dominant autosomal deafness, it is still unclear why gap junctions are essential for auditory function, and why Cx26 and Cx30 do not compensate for each other in vivo. Cx26 appears to be essential for normal development of the auditory sensory epithelium, but may be dispensable during normal hearing. Cx30 appears to be essential for normal repair following sensory cell loss. The specific modes of intercellular signalling mediated by inner ear gap junction channels remain undetermined, but they are hypothesised to play essential roles in the maintenance of ionic and metabolic homeostasis in the inner ear. Recent studies have highlighted involvement of gap junctions in the transfer of essential second messengers between the non-sensory cells, and have proposed roles for hemichannels in normal hearing. Here, we summarise the current knowledge about the molecular and functional properties of inner ear gap junctions, and about tissue pathologies associated with connexin mutations.
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Affiliation(s)
- Daniel J Jagger
- UCL Ear Institute, University College London, 332 Gray's Inn Road, London, WC1X 8EE, UK,
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Abdel-Hafez AMM, Elgayar SAM, Husain OA, Thabet HSA. Effect of nicotine on the structure of cochlea of guinea pigs. Anat Cell Biol 2014; 47:162-70. [PMID: 25276475 PMCID: PMC4178191 DOI: 10.5115/acb.2014.47.3.162] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2014] [Revised: 09/11/2014] [Accepted: 09/15/2014] [Indexed: 11/30/2022] Open
Abstract
Smoking has been positively associated with hearing loss in human. However, its effect on the cochlea has not been previously evaluated. Aim of work is to investigate the effect of nicotine, which is the primary pharmacological component of tobacco, on the structure of the cochlea of adult male guinea pigs. Fifteen male guinea pigs were classified into two groups: group I (control) and group II (nicotine treated group). Group II was further subdivided into two subgroups; IIA and IIB according to the dose of nicotine (3 mg/kg and 6 mg/kg, respectively). The cochlea was harvested and processed for light microscopy, transmission electron microscopy and scanning electron microscopy. Nicotine administration induced damage of outer hair cells which were distorted in shape with vacuolated cytoplasm and heterochromatic nuclei. Topography revealed damage of the stereocilia which included disorganization, bent and limp or complete loss and expansion of the surrounding supporting cells. These changes were more pronounced in the basal turn of the cochlea and mainly involved the outer hair cells. High dose induced more damage and resulted in protrusion of the apical poles of hair cells (blebing), particularly the outer two rows. Nicotine is proved to be harmful to the cells of the cochlea, particularly the outer hair cells of the basal turn. High doses induce blebing of hair cells.
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Affiliation(s)
| | - Sanaa A M Elgayar
- Department of Histology, Faculty of Medicine, Assiut University, Assiut, Egypt
| | - Ola A Husain
- Department of Histology, Faculty of Medicine, Assiut University, Assiut, Egypt
| | - Huda S A Thabet
- Department of Histology, Faculty of Medicine, Assiut University, Assiut, Egypt
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Irving S, Wise AK, Millard RE, Shepherd RK, Fallon JB. A partial hearing animal model for chronic electro-acoustic stimulation. J Neural Eng 2014; 11:046008. [PMID: 24921595 PMCID: PMC4116305 DOI: 10.1088/1741-2560/11/4/046008] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
Abstract
OBJECTIVE Cochlear implants (CIs) have provided some auditory function to hundreds of thousands of people around the world. Although traditionally carried out only in profoundly deaf patients, the eligibility criteria for implantation have recently been relaxed to include many partially-deaf patients with useful levels of hearing. These patients receive both electrical stimulation from their implant and acoustic stimulation via their residual hearing (electro-acoustic stimulation; EAS) and perform very well. It is unclear how EAS improves speech perception over electrical stimulation alone, and little evidence exists about the nature of the interactions between electric and acoustic stimuli. Furthermore, clinical results suggest that some patients that undergo cochlear implantation lose some, if not all, of their residual hearing, reducing the advantages of EAS over electrical stimulation alone. A reliable animal model with clinically-relevant partial deafness combined with clinical CIs is important to enable these issues to be studied. This paper outlines such a model that has been successfully used in our laboratory. APPROACH This paper outlines a battery of techniques used in our laboratory to generate, validate and examine an animal model of partial deafness and chronic CI use. MAIN RESULTS Ototoxic deafening produced bilaterally symmetrical hearing thresholds in neonatal and adult animals. Electrical activation of the auditory system was confirmed, and all animals were chronically stimulated via adapted clinical CIs. Acoustic compound action potentials (CAPs) were obtained from partially-hearing cochleae, using the CI amplifier. Immunohistochemical analysis allows the effects of deafness and electrical stimulation on cell survival to be studied. SIGNIFICANCE This animal model has applications in EAS research, including investigating the functional interactions between electric and acoustic stimulation, and the development of techniques to maintain residual hearing following cochlear implantation. The ability to record CAPs via the CI has clinical direct relevance for obtaining objective measures of residual hearing.
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Affiliation(s)
- S Irving
- Bionics Institute, Melbourne, Australia. University of Melbourne, Melbourne, Australia
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Anttonen T, Belevich I, Kirjavainen A, Laos M, Brakebusch C, Jokitalo E, Pirvola U. How to bury the dead: elimination of apoptotic hair cells from the hearing organ of the mouse. J Assoc Res Otolaryngol 2014; 15:975-92. [PMID: 25074370 DOI: 10.1007/s10162-014-0480-x] [Citation(s) in RCA: 42] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2014] [Accepted: 07/01/2014] [Indexed: 12/20/2022] Open
Abstract
Hair cell death is a major cause of hearing impairment. Preservation of surface barrier upon hair cell loss is critical to prevent leakage of potassium-rich endolymph into the organ of Corti and to prevent expansion of cellular damage. Understanding of wound healing in this cytoarchitecturally complex organ requires ultrastructural 3D visualization. Powered by the serial block-face scanning electron microscopy, we penetrate into the cell biological mechanisms in the acute response of outer hair cells and glial-like Deiters' cells to ototoxic trauma in vivo. We show that Deiters' cells function as phagocytes. Upon trauma, their phalangeal processes swell and the resulting close cellular contacts allow engulfment of apoptotic cell debris. Apical domains of dying hair cells are eliminated from the inner ear sensory epithelia, an event thought to depend on supporting cells' actomyosin contractile activity. We show that in the case of apoptotic outer hair cells of the organ of Corti, elimination of their apices is preceded by strong cell body shrinkage, emphasizing the role of the dying cell itself in the cleavage. Our data reveal that the resealing of epithelial surface by junctional extensions of Deiters' cells is dynamically reinforced by newly polymerized F-actin belts. By analyzing Cdc42-inactivated Deiters' cells with defects in actin dynamics and surface closure, we show that compromised barrier integrity shifts hair cell death from apoptosis to necrosis and leads to expanded hair cell and nerve fiber damage. Our results have implications concerning therapeutic protective and regenerative interventions, because both interventions should maintain barrier integrity.
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Affiliation(s)
- Tommi Anttonen
- Department of Biosciences, University of Helsinki, P.O. Box 56 (Viikinkaari 1), 00014, Helsinki, Finland
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Mechanisms of radiation-induced sensorineural hearing loss and radioprotection. Hear Res 2014; 312:60-8. [DOI: 10.1016/j.heares.2014.03.003] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/09/2013] [Revised: 02/12/2014] [Accepted: 03/07/2014] [Indexed: 12/20/2022]
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Atkinson PJ, Wise AK, Flynn BO, Nayagam BA, Richardson RT. Viability of long-term gene therapy in the cochlea. Sci Rep 2014; 4:4733. [PMID: 24751795 PMCID: PMC3994438 DOI: 10.1038/srep04733] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2013] [Accepted: 04/01/2014] [Indexed: 12/16/2022] Open
Abstract
Gene therapy has been investigated as a way to introduce a variety of genes to treat neurological disorders. An important clinical consideration is its long-term effectiveness. This research aims to study the long-term expression and effectiveness of gene therapy in promoting spiral ganglion neuron survival after deafness. Adenoviral vectors modified to express brain derived neurotrophic factor or neurotrophin-3 were unilaterally injected into the guinea pig cochlea one week post ototoxic deafening. After six months, persistence of gene expression and significantly greater neuronal survival in neurotrophin-treated cochleae compared to the contralateral cochleae were observed. The long-term gene expression observed indicates that gene therapy is potentially viable; however the degeneration of the transduced cells as a result of the original ototoxic insult may limit clinical effectiveness. With further research aimed at transducing stable cochlear cells, gene therapy may be an efficacious way to introduce neurotrophins to promote neuronal survival after hearing loss.
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Affiliation(s)
- Patrick J Atkinson
- 1] Bionics Institute, East Melbourne, Victoria, Australia [2] Department of Otolaryngology, University of Melbourne, East Melbourne, Victoria, Australia
| | - Andrew K Wise
- 1] Bionics Institute, East Melbourne, Victoria, Australia [2] Department of Otolaryngology, University of Melbourne, East Melbourne, Victoria, Australia [3] Department of Medical Bionics, University of Melbourne, East Melbourne, Victoria, Australia
| | | | - Bryony A Nayagam
- 1] Bionics Institute, East Melbourne, Victoria, Australia [2] Department of Audiology and Speech Pathology, University of Melbourne, Parkville, Victoria, Australia
| | - Rachael T Richardson
- 1] Bionics Institute, East Melbourne, Victoria, Australia [2] Department of Otolaryngology, University of Melbourne, East Melbourne, Victoria, Australia [3] Department of Medical Bionics, University of Melbourne, East Melbourne, Victoria, Australia
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Martone T, Giordano P, Dagna F, Carulli D, Albera R, Rossi F. Nestin expression and reactive phenomena in the mouse cochlea after kanamycin ototoxicity. Eur J Neurosci 2014; 39:1729-41. [PMID: 24689961 DOI: 10.1111/ejn.12576] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2013] [Accepted: 02/28/2014] [Indexed: 11/28/2022]
Abstract
Following injury to the adult mammalian cochlea, hair cells cannot be spontaneously replaced. Nonetheless, the postnatal cochlea contains progenitor cells, distinguished by the expression of nestin, which are able to proliferate and form neurospheres in vitro. Such resident progenitors might be endowed with reparative potential. However, to date little is known about their behaviour in situ following hair cell injury. Using adult mice and ex vivo cochlear cultures, we sought to determine whether: (i) resident cochlear progenitors respond to kanamycin ototoxicity and compensate for it; and (ii) the reparative potential of cochlear progenitors can be stimulated by the addition of growth factors. Morphological changes of cochlear tissue, expression of nestin mRNA and protein and cell proliferation were investigated in these models. Our observations show that ototoxic injury has modest effects on nestin expression and cell proliferation. On the other hand, the addition of growth factors to the injured cochlear explants induced the appearance of nestin-positive cells in the supporting cell area of the organ of Corti. The vast majority of nestin-expressing cells, however, were not proliferating. Growth factors also had a robust stimulatory effect on axonal sprouting and the proliferative response, which was more pronounced in injured cochleae. On the whole, our findings indicate that nestin expression after kanamycin ototoxicity is related to tissue reactivity rather than activation of resident progenitors attempting to replace the lost receptors. In addition, administration of growth factors significantly enhances tissue remodelling, suggesting that cochlear repair may be promoted by the exogenous application of regeneration-promoting substances.
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Affiliation(s)
- Tiziana Martone
- Department of Neuroscience, Neuroscience Institute of Turin (NIT), Turin, Italy; Neuroscience Institute Cavalieri-Ottolenghi (NICO), University of Turin, Orbassano, Turin, Italy
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Jagger DJ, Forge A. The enigmatic root cell – Emerging roles contributing to fluid homeostasis within the cochlear outer sulcus. Hear Res 2013; 303:1-11. [DOI: 10.1016/j.heares.2012.10.010] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/31/2012] [Revised: 10/19/2012] [Accepted: 10/26/2012] [Indexed: 12/20/2022]
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Korrapati S, Roux I, Glowatzki E, Doetzlhofer A. Notch signaling limits supporting cell plasticity in the hair cell-damaged early postnatal murine cochlea. PLoS One 2013; 8:e73276. [PMID: 24023676 PMCID: PMC3758270 DOI: 10.1371/journal.pone.0073276] [Citation(s) in RCA: 65] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/10/2013] [Accepted: 07/18/2013] [Indexed: 12/02/2022] Open
Abstract
In mammals, auditory hair cells are generated only during embryonic development and loss or damage to hair cells is permanent. However, in non-mammalian vertebrate species, such as birds, neighboring glia-like supporting cells regenerate auditory hair cells by both mitotic and non-mitotic mechanisms. Based on work in intact cochlear tissue, it is thought that Notch signaling might restrict supporting cell plasticity in the mammalian cochlea. However, it is unresolved how Notch signaling functions in the hair cell-damaged cochlea and the molecular and cellular changes induced in supporting cells in response to hair cell trauma are poorly understood. Here we show that gentamicin-induced hair cell loss in early postnatal mouse cochlear tissue induces rapid morphological changes in supporting cells, which facilitate the sealing of gaps left by dying hair cells. Moreover, we provide evidence that Notch signaling is active in the hair cell damaged cochlea and identify Hes1, Hey1, Hey2, HeyL, and Sox2 as targets and potential Notch effectors of this hair cell-independent mechanism of Notch signaling. Using Cre/loxP based labeling system we demonstrate that inhibition of Notch signaling with a γ- secretase inhibitor (GSI) results in the trans-differentiation of supporting cells into hair cell-like cells. Moreover, we show that these hair cell-like cells, generated by supporting cells have molecular, cellular, and basic electrophysiological properties similar to immature hair cells rather than supporting cells. Lastly, we show that the vast majority of these newly generated hair cell-like cells express the outer hair cell specific motor protein prestin.
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Affiliation(s)
- Soumya Korrapati
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Center for Hearing and Balance, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
| | - Isabelle Roux
- Department of Otolaryngology, Head and Neck Surgery, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Center for Hearing and Balance, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
| | - Elisabeth Glowatzki
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Department of Otolaryngology, Head and Neck Surgery, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Center for Hearing and Balance, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
| | - Angelika Doetzlhofer
- Solomon H. Snyder Department of Neuroscience, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Department of Otolaryngology, Head and Neck Surgery, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Center for Sensory Biology, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- Center for Hearing and Balance, Johns Hopkins University, School of Medicine, Baltimore, Maryland, United States of America
- * E-mail:
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Ladrech S, Mathieu M, Puel JL, Lenoir M. Supporting cells regulate the remodelling of aminoglycoside-injured organ of Corti, through the release of high mobility group box 1. Eur J Neurosci 2013; 38:2962-72. [DOI: 10.1111/ejn.12290] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2012] [Revised: 05/29/2013] [Accepted: 06/03/2013] [Indexed: 11/28/2022]
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