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Okano T, Kelley MW. Stem cell therapy for the inner ear: recent advances and future directions. Trends Amplif 2012; 16:4-18. [PMID: 22514095 DOI: 10.1177/1084713812440336] [Citation(s) in RCA: 56] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
In vertebrates, perception of sound, motion, and balance is mediated through mechanosensory hair cells located within the inner ear. In mammals, hair cells are only generated during a short period of embryonic development. As a result, loss of hair cells as a consequence of injury, disease, or genetic mutation, leads to permanent sensory deficits. At present, cochlear implantation is the only option for profound hearing loss. However, outcomes are still variable and even the best implant cannot provide the acuity of a biological ear. The recent emergence of stem cell technology has the potential to open new approaches for hair cell regeneration. The goal of this review is to summarize the current state of inner ear stem cell research from a viewpoint of its clinical application for inner ear disorders to illustrate how complementary studies have the potential to promote and refine stem cell therapies for inner ear diseases. The review initially discusses our current understanding of the genetic pathways that regulate hair cell formation from inner ear progenitors during normal development. Subsequent sections discuss the possible use of endogenous inner ear stem cells to induce repair as well as the initial studies aimed at transplanting stem cells into the ear.
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152
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Atoh1, an essential transcription factor in neurogenesis and intestinal and inner ear development: function, regulation, and context dependency. J Assoc Res Otolaryngol 2012; 13:281-93. [PMID: 22370966 DOI: 10.1007/s10162-012-0317-4] [Citation(s) in RCA: 79] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2011] [Accepted: 02/06/2012] [Indexed: 01/07/2023] Open
Abstract
Atoh1 (also known as Math1, Hath1, and Cath1 in mouse, human, and chicken, respectively) is a proneural basic helix-loop-helix (bHLH) transcription factor that is required in a variety of developmental contexts. Atoh1 is involved in differentiation of neurons, secretory cells in the gut, and mechanoreceptors including auditory hair cells. Together with the two closely related bHLH genes, Neurog1 and NeuroD1, Atoh1 regulates neurosensory development in the ear as well as neurogenesis in the cerebellum. Atoh1 activity in the cochlea is both necessary and sufficient to drive auditory hair cell differentiation, in keeping with its known role as a regulator of various genes that are markers of terminal differentiation. Atoh1 is known in other fields as an oncogene and a tumor suppressor involved in regulation of cell cycle control and apoptosis. Aberrant Atoh1 activity in adult tissue is implicated in cancer progression, specifically in medullablastoma and adenomatous polyposis carcinoma. We demonstrate through protein sequence comparison that Atoh1 contains conserved phosphorylation sites outside the bHLH domain, which may allow regulation through post-translational modification. With such diverse roles, tight regulation of Atoh1 at both the transcriptional and protein level is essential.
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153
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Taylor RR, Jagger DJ, Forge A. Defining the cellular environment in the organ of Corti following extensive hair cell loss: a basis for future sensory cell replacement in the Cochlea. PLoS One 2012; 7:e30577. [PMID: 22299045 PMCID: PMC3267727 DOI: 10.1371/journal.pone.0030577] [Citation(s) in RCA: 59] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2011] [Accepted: 12/21/2011] [Indexed: 01/01/2023] Open
Abstract
Background Following the loss of hair cells from the mammalian cochlea, the sensory epithelium repairs to close the lesions but no new hair cells arise and hearing impairment ensues. For any cell replacement strategy to be successful, the cellular environment of the injured tissue has to be able to nurture new hair cells. This study defines characteristics of the auditory sensory epithelium after hair cell loss. Methodology/Principal Findings Studies were conducted in C57BL/6 and CBA/Ca mice. Treatment with an aminoglycoside-diuretic combination produced loss of all outer hair cells within 48 hours in both strains. The subsequent progressive tissue re-organisation was examined using immunohistochemistry and electron microscopy. There was no evidence of significant de-differentiation of the specialised columnar supporting cells. Kir4.1 was down regulated but KCC4, GLAST, microtubule bundles, connexin expression patterns and pathways of intercellular communication were retained. The columnar supporting cells became covered with non-specialised cells migrating from the outermost region of the organ of Corti. Eventually non-specialised, flat cells replaced the columnar epithelium. Flat epithelium developed in distributed patches interrupting regions of columnar epithelium formed of differentiated supporting cells. Formation of the flat epithelium was initiated within a few weeks post-treatment in C57BL/6 mice but not for several months in CBA/Ca's, suggesting genetic background influences the rate of re-organisation. Conclusions/Significance The lack of dedifferentiation amongst supporting cells and their replacement by cells from the outer side of the organ of Corti are factors that may need to be considered in any attempt to promote endogenous hair cell regeneration. The variability of the cellular environment along an individual cochlea arising from patch-like generation of flat epithelium, and the possible variability between individuals resulting from genetic influences on the rate at which remodelling occurs may pose challenges to devising the appropriate regenerative therapy for a deaf patient.
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Affiliation(s)
- Ruth R Taylor
- Centre for Auditory Research, The Ear Institute, University College London, London, United Kingdom.
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154
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Notch signaling and the developing inner ear. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2012; 727:161-73. [PMID: 22399346 DOI: 10.1007/978-1-4614-0899-4_12] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Sensory hair cells (HCs) and their associated nonsensory supporting cells (SCs) exhibit a typical mosaic pattern in each of the sensory patches in the inner ear. Notch signaling has been considered to conduct the formation of this mosaic pattern through one of its famous functions, known as 'lateral inhibition'. The two Notch ligands Delta-like1 and Jagged2 are believed to act synergistically at the stage of cell diversification in mammals. In addition, many current studies suggest that Notch signaling has another inductive, but not inhibiting, role in the determination of the prosensory region, which precedes the cell diversification of HCs and SCs and Jagged1 is thought to be an essential ligand in this process. Earlier in ear development, the first cell fate determination begins with the delamination of the neuroblasts from the otic epithelium. The delaminated neuroblasts migrate and coalesce to form cochleovestibular ganglion. Notch signaling pathway is thought to function during the delamination through its lateral inhibitory mechanism. Recently, many experiments examining Notch-related gene expression patterns and direct functional analyses of genes have revealed multiple important functions of Notch in inner ear development. Here, we survey a series of studies and discuss the issues that remain to be elucidated in the future.
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155
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Inhibition of Notch activity promotes nonmitotic regeneration of hair cells in the adult mouse utricles. J Neurosci 2011; 31:15329-39. [PMID: 22031879 DOI: 10.1523/jneurosci.2057-11.2011] [Citation(s) in RCA: 127] [Impact Index Per Article: 9.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
The capacity of adult mammals to regenerate sensory hair cells is not well defined. To explore early steps in this process, we examined reactivation of a transiently expressed developmental gene, Atoh1, in adult mouse utricles after neomycin-induced hair cell death in culture. Using an adenoviral reporter for Atoh1 enhancer, we found that Atoh1 transcription is activated in some hair cell progenitors (supporting cells) 3 d after neomycin treatment. By 18 d after neomycin, the number of cells with Atoh1 transcriptional activity increased significantly, but few cells acquired hair cell features (i.e., accumulated ATOH1 or myosin VIIa protein or developed stereocilia). Treatment with DAPT, an inhibitor of γ-secretase, reduced notch pathway activity, enhanced Atoh1 transcriptional activity, and dramatically increased the number of Atoh1-expressing cells with hair cell features, but only in the striolar/juxtastriolar region. Similar effects were seen with TAPI-1, an inhibitor of another enzyme required for notch activity (TACE). Division of supporting cells was rare in any control or DAPT-treated utricles. This study shows that mature mammals have a natural capacity to initiate vestibular hair cell regeneration and suggests that regional notch activity is a significant inhibitor of direct transdifferentiation of supporting cells into hair cells following damage.
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156
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Werner M, Van De Water TR, Andersson T, Arnoldsson G, Berggren D. Morphological and morphometric characteristics of vestibular hair cells and support cells in long term cultures of rat utricle explants. Hear Res 2011; 283:107-16. [PMID: 22127330 DOI: 10.1016/j.heares.2011.11.003] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 01/18/2011] [Revised: 10/31/2011] [Accepted: 11/03/2011] [Indexed: 11/27/2022]
Abstract
A method for long term culture of utricular macula explants is demonstrated to be stable and reproducible over a period of 28 days in vitro (DIV). This culture system for four-day-old rat utricular maculae is potentially suitable for studies of hair cell loss, repair and regeneration processes as they occur in post-natal mammalian inner ear sensory epithelia. The cellular events that occur within utricular macula hair cell epithelia during 28 days of culture are documented from serial sections. Vestibular hair cells (HCs) and supporting cells (SCs) were systematically counted using light microscopy (LM) and the assistance of morphometric computer software. Ultrastructural observations were made with transmission electron microscopy (TEM) for describing the changes in the fine detailed morphological characteristics that occurred in the explants related to time in vitro. After 2 DIV the density of HCs was 77%, at 21 DIV it was 69%, and at 28 DIV it was 52% of HCs present at explantation. Between 2 DIV and 28 DIV there was a 1.7% decrease of the vestibular macula HC density per DIV. The corresponding decrease of SC density within the utricular explants was less than 1% per DIV. The overall morphology of the epithelia, i.e. relationship of HCs to SCs, was well preserved during the first two weeks in culture. After this time a slight deterioration of the epithelia was observed and although type I and type II HCs were identified by TEM observations, these two HC types could no longer be distinguished from one another by LM observations. In preparations cultured for 21 DIV, SC nuclei were located more apical and further away from the basal membrane compared to their position in macula explants fixed immediately after dissection. The loss of cells that occurred was probably due to expulsion from the apical (i.e. luminal) surface of the sensory epithelia, but no lesions of the apical lining or ruptures of the basal membrane were observed. There were no significant changes in the volume of the vestibular HC comprising macular epithelium during the observation period of 28 DIV.
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Affiliation(s)
- Mimmi Werner
- Department of Clinical Sciences/Otolaryngology, University of Umeå, Umeå, Sweden
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157
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Watanabe R, Morell MH, Miller JM, Kanicki AC, O'Shea KS, Altschuler RA, Raphael Y. Nestin-expressing cells in the developing, mature and noise-exposed cochlear epithelium. Mol Cell Neurosci 2011; 49:104-9. [PMID: 22122823 DOI: 10.1016/j.mcn.2011.11.001] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2011] [Revised: 10/30/2011] [Accepted: 11/10/2011] [Indexed: 01/06/2023] Open
Abstract
The auditory sensory epithelium in non-mammalian vertebrates can replace lost hair cells by transdifferentiation of supporting cells, but this regenerative ability is lost in the mammalian cochlea. Future cell-based treatment of hearing loss may depend on stem cell transplantation or on transdifferentiation of endogenous cells in the cochlea. For both approaches, identification of cells with stem cell features within the mature cochlea may be useful. Here we use a Nestin-β-gal mouse to examine the presence of Nestin positive cells in the mature auditory epithelium, and determine how overstimulation of the ear impacts these cells. Nestin positive cells were found in the apical turn of the cochlea lateral to the outer hair cell area. This pattern of expression persisted into mature age. The area of Nestin positive cells was increased after the noise lesion. This increase in area coincided with an increase in expression of the Nestin mRNA. The data suggest that cells with potential stem cell features remain in the mature mammalian cochlea, restricted to the apical turn, and that an additional set of signals is necessary to trigger their contribution to cell replacement therapy in the ear. As such, this population of cells could serve to generate cochlear stem cells for research and potential therapy, and may be a target for treatments based on induced transdifferentiation of endogenous cochlear cells.
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Affiliation(s)
- Reiko Watanabe
- Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, MI 48109-5648, USA
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158
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Makishima T, Hochman L, Armstrong P, Rosenberger E, Ridley R, Woo M, Perachio A, Wood S. Inner ear dysfunction in caspase-3 deficient mice. BMC Neurosci 2011; 12:102. [PMID: 21988729 PMCID: PMC3208590 DOI: 10.1186/1471-2202-12-102] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/19/2011] [Accepted: 10/12/2011] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Caspase-3 is one of the most downstream enzymes activated in the apoptotic pathway. In caspase-3 deficient mice, loss of cochlear hair cells and spiral ganglion cells coincide closely with hearing loss. In contrast with the auditory system, details of the vestibular phenotype have not been characterized. Here we report the vestibular phenotype and inner ear anatomy in the caspase-3 deficient (Casp3(-/-)) mouse strain. RESULTS Average ABR thresholds of Casp3(-/-) mice were significantly elevated (P < 0.05) compared to Casp3(+/-) mice and Casp3(+/+) mice at 3 months of age. In DPOAE testing, distortion product 2F1-F2 was significantly decreased (P < 0.05) in Casp3(-/-) mice, whereas Casp3(+/-) and Casp3(+/+) mice showed normal and comparable values to each other. Casp3(-/-) mice were hyperactive and exhibited circling behavior when excited. In lateral canal VOR testing, Casp3(-/-) mice had minimal response to any of the stimuli tested, whereas Casp3(+/-) mice had an intermediate response compared to Casp3(+/+) mice. Inner ear anatomical and histological analysis revealed gross hypomorphism of the vestibular organs, in which the main site was the anterior semicircular canal. Hair cell numbers in the anterior- and lateral crista, and utricle were significantly smaller in Casp3(-/-) mice whereas the Casp3(+/-) and Casp3(+/+) mice had normal hair cell numbers. CONCLUSIONS These results indicate that caspase-3 is essential for correct functioning of the cochlea as well as normal development and function of the vestibule.
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Affiliation(s)
- Tomoko Makishima
- Department of Otolaryngology, University of Texas Medical Branch, Galveston, Texas, USA.
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159
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Ferretti P. Is there a relationship between adult neurogenesis and neuron generation following injury across evolution? Eur J Neurosci 2011; 34:951-62. [DOI: 10.1111/j.1460-9568.2011.07833.x] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/18/2023]
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160
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Schuck JB, Sun H, Penberthy WT, Cooper NGF, Li X, Smith ME. Transcriptomic analysis of the zebrafish inner ear points to growth hormone mediated regeneration following acoustic trauma. BMC Neurosci 2011; 12:88. [PMID: 21888654 PMCID: PMC3175199 DOI: 10.1186/1471-2202-12-88] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2011] [Accepted: 09/02/2011] [Indexed: 01/13/2023] Open
Abstract
Background Unlike mammals, teleost fishes are capable of regenerating sensory inner ear hair cells that have been lost following acoustic or ototoxic trauma. Previous work indicated that immediately following sound exposure, zebrafish saccules exhibit significant hair cell loss that recovers to pre-treatment levels within 14 days. Following acoustic trauma in the zebrafish inner ear, we used microarray analysis to identify genes involved in inner ear repair following acoustic exposure. Additionally, we investigated the effect of growth hormone (GH) on cell proliferation in control zebrafish utricles and saccules, since GH was significantly up-regulated following acoustic trauma. Results Microarray analysis, validated with the aid of quantitative real-time PCR, revealed several genes that were highly regulated during the process of regeneration in the zebrafish inner ear. Genes that had fold changes of ≥ 1.4 and P -values ≤ 0.05 were considered significantly regulated and were used for subsequent analysis. Categories of biological function that were significantly regulated included cancer, cellular growth and proliferation, and inflammation. Of particular significance, a greater than 64-fold increase in growth hormone (gh1) transcripts occurred, peaking at 2 days post-sound exposure (dpse) and decreasing to approximately 5.5-fold by 4 dpse. Pathway Analysis software was used to reveal networks of regulated genes and showed how GH affected these networks. Subsequent experiments showed that intraperitoneal injection of salmon growth hormone significantly increased cell proliferation in the zebrafish inner ear. Many other gene transcripts were also differentially regulated, including heavy and light chain myosin transcripts, both of which were down-regulated following sound exposure, and major histocompatability class I and II genes, several of which were significantly regulated on 2 dpse. Conclusions Transcripts for GH, MHC Class I and II genes, and heavy- and light-chain myosins, as well as many others genes, were differentially regulated in the zebrafish inner ear following overexposure to sound. GH injection increased cell proliferation in the inner ear of non-sound-exposed zebrafish, suggesting that GH could play an important role in sensory hair cell regeneration in the teleost ear.
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Affiliation(s)
- Julie B Schuck
- Department of Biology, Western Kentucky University, 1906 College Heights Blvd, Bowling Green, KY 42101, USA
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161
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Collado MS, Burns JC, Meyers JR, Corwin JT. Variations in shape-sensitive restriction points mirror differences in the regeneration capacities of avian and mammalian ears. PLoS One 2011; 6:e23861. [PMID: 21909368 PMCID: PMC3166124 DOI: 10.1371/journal.pone.0023861] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2011] [Accepted: 07/26/2011] [Indexed: 01/05/2023] Open
Abstract
When inner ear hair cells die, humans and other mammals experience permanent hearing and balance deficits, but non-mammalian vertebrates quickly recover these senses after epithelial supporting cells give rise to replacement hair cells. A postnatal decline in cellular plasticity appears to limit regeneration in mammalian balance organs, where declining proliferation responses are correlated with decreased spreading of supporting cells on artificial and native substrates. By culturing balance epithelia on substrates that differed in flexibility, we assessed spreading effects independent of age, showing a strong correlation between shape change and supporting cell proliferation. Then we made excision wounds in utricles cultured from young and old chickens and mice and compared quantified levels of spreading and proliferation. In utricles from young mice, and both young and old chickens, wounds re-epithelialized in <24 hours, while those in utricles from mature mice took three times longer. More cells changed shape in the fastest healing wounds, which accounted for some differences in the levels of proliferation, but inter-species and age-related differences in shape-sensitive restriction points, i.e., the cellular thresholds for shape changes that promote S-phase, were evident and may be particularly influential in the responses to hair cell losses in vivo.
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Affiliation(s)
- Maria Sol Collado
- Department of Neuroscience, University of Virginia School of Medicine, Charlottesville, Virginia, United States of America.
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162
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Karasawa T, Steyger PS. Intracellular mechanisms of aminoglycoside-induced cytotoxicity. Integr Biol (Camb) 2011; 3:879-86. [PMID: 21799993 DOI: 10.1039/c1ib00034a] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/25/2022]
Abstract
Since introduction into clinical practice over 60 years ago, aminoglycoside antibiotics remain important drugs in the treatment of bacterial infections, cystic fibrosis and tuberculosis. However, the ototoxic and nephrotoxic properties of these drugs are still a major clinical problem. Recent advances in molecular biology and biochemistry have begun to uncover the intracellular actions of aminoglycosides that lead to cytotoxicity. In this review, we discuss intracellular binding targets of aminoglycosides, highlighting specific aminoglycoside-binding proteins (HSP73, calreticulin and CLIMP-63) and their potential for triggering caspases and Bcl-2 signalling cascades that are involved in aminoglycoside-induced cytotoxicity. We also discuss potential strategies to reduce aminoglycoside cytotoxicity, which are necessary for greater bactericidal efficacy during aminoglycoside pharmacotherapy.
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Affiliation(s)
- Takatoshi Karasawa
- Oregon Hearing Research Center, Oregon Health & Science University, 3181 SW Sam Jackson Park Road, Portland, Oregon 97239, USA.
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163
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Marano RJ, Redmond SL. In vitro cultured primary cells from a human utricle explant possesses hair cell like characteristics. J Mol Histol 2011; 42:365-70. [PMID: 21660457 DOI: 10.1007/s10735-011-9333-7] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2011] [Accepted: 05/24/2011] [Indexed: 11/27/2022]
Abstract
The utricle is the enlarged portion of the membranous labyrinth of the inner ear and is essential for balance. It comprises of fine hair cells (mechanoreceptors), supporting cells and calcareous otoliths. Utricle cells are considered to be post-mitotic and possess a limited capacity for regeneration. Unlike birds and reptiles, mammalian mechanosensory hair cells do not regenerate. The in vitro culture of primary cells from the utricle and other inner ear structures of mammals have proven difficult. Presented here for the first time is the culture of primary cells derived from an explant of an adult human utricle, without any intervention or manipulation. Cells were proliferative until cellular quiescence occurred during passage six. Cell morphology was atypical of epithelial cells, appearing as a homogenous, slightly elongated population. Analysis of cultured utricle cells by immunofluorescent staining (IF) and reverse transcriptase polymerase chain reaction (RT-PCR) have shown these cells to possess epithelial (Epithelium-specific ets-1 (ESE-1)), supporting hair cell (p27(Kip1)), and hair cell specific (Atoh1 and Myosin VI) markers. Additionally, RT-PCR revealed positive gene expression for the proliferation control marker fibroblast growth factor receptor 1 (FGFR1) and negative gene expression for E-cadherin (CDH1), a vestibular cell differentiation marker.
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Affiliation(s)
- Robert J Marano
- Molecular and Cellular Otolaryngology Research Laboratory, Ear Science Institute Australia, 2nd Floor, M Block, Room 2.27 (M507), QEII Medical Centre, Nedlands, WA, 6009, Australia.
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164
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Warchol ME. Sensory regeneration in the vertebrate inner ear: Differences at the levels of cells and species. Hear Res 2011; 273:72-9. [DOI: 10.1016/j.heares.2010.05.004] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/17/2009] [Revised: 05/03/2010] [Accepted: 05/12/2010] [Indexed: 12/31/2022]
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165
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Huang M, Sage C, Tang Y, Lee SG, Petrillo M, Hinds PW, Chen ZY. Overlapping and distinct pRb pathways in the mammalian auditory and vestibular organs. Cell Cycle 2011; 10:337-51. [PMID: 21239885 DOI: 10.4161/cc.10.2.14640] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Retinoblastoma gene (Rb1) is required for proper cell cycle exit in the developing mouse inner ear and its deletion in the embryo leads to proliferation of sensory progenitor cells that differentiate into hair cells and supporting cells. In a conditional hair cell Rb1 knockout mouse, Pou4f3-Cre-pRb(-/-), pRb(-/-) utricular hair cells differentiate and survive into adulthood whereas differentiation and survival of pRb(-/-) cochlear hair cells are impaired. To comprehensively survey the pRb pathway in the mammalian inner ear, we performed microarray analysis of (pRb(-/-) cochlea and utricle. The comparative analysis shows that the core pathway shared between pRb(-/-) cochlea and utricle is centered on E2F, the key pathway that mediates pRb function. A majority of differentially expressed genes and enriched pathways are not shared but uniquely associated with pRb(-/-) cochlea or utricle. In pRb(-/-) cochlea, pathways involved in early inner ear development such as Wnt/β-catenin and Notch were enriched, whereas pathways involving in proliferation and survival are enriched in pRb(-/-) utricle. Clustering analysis showed that the pRb(-/-) inner ear has characteristics of a younger control inner ear, an indication of delayed differentiation. We created a transgenic mouse model (ER-Cre-pRb(flox/flox)) in which Rb1 can be acutely deleted postnatally. Acute Rb1 deletion in the adult mouse fails to induce proliferation or cell death in inner ear, strongly indicating that Rb1 loss in these postmitotic tissues can be effectively compensated for, or that pRb-mediated changes in the postmitotic compartment result in events that are functionally irreversible once enacted. This study thus supports the concept that pRb-regulated pathways relevant to hair cell development, encompassing proliferation, differentiation and survival, act predominantly during early development.
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Affiliation(s)
- Mingqian Huang
- Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts, USA
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166
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Changes in corneal basal epithelial phenotypes in an altered basement membrane. PLoS One 2011; 6:e14537. [PMID: 21264285 PMCID: PMC3021502 DOI: 10.1371/journal.pone.0014537] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/24/2010] [Accepted: 12/20/2010] [Indexed: 12/13/2022] Open
Abstract
Background To examine the corneal epithelial phenotype in an altered basement membrane. Methodology/Principal Findings Corneas from 9 patients with symptoms of continuous unstable corneal curvature (CUCC) were harvested by penetrating keratoplasty and subjected to histology examination and immunohistochemical staining with transactivating and N-terminally truncated pP63 transcript (ΔNp63), cytokeratin 3 (Krt3), ATP-binding cassette sub-family G member 2 (ABCG2), connexin 43 (CX43), p38 mitogen-activated protein kinases (p38MAPK), activating protein 2 (TFAP2), and extracellular signal-regulated kinase (Erk1/2) monoclonal antibodies. Positive immunostaining with ABCG2, p38MAPK, and TFAP2 monoclonal antibodies was observed in the basal epithelial cells of CUCC patients, and CX43 and ΔNp63 were detected in the full-thickness epithelial cells of CUCC patients. Conclusions/Significance Our results indicate that alteration of the corneal basement membrane induces a de-differentiation-like phenotype in corneal basal epithelial cells.
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167
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168
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The Development of a Stem Cell Therapy for Deafness. Regen Med 2011. [DOI: 10.1007/978-90-481-9075-1_27] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022] Open
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169
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Inokuchi JI. Physiopathological function of hematoside (GM3 ganglioside). PROCEEDINGS OF THE JAPAN ACADEMY. SERIES B, PHYSICAL AND BIOLOGICAL SCIENCES 2011; 87:179-98. [PMID: 21558756 PMCID: PMC3149380 DOI: 10.2183/pjab.87.179] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/10/2023]
Abstract
Since I was involved in the molecular cloning of GM3 synthase (SAT-I), which is the primary enzyme for the biosynthesis of gangliosides in 1998, my research group has been concentrating on our efforts to explore the physiological and pathological implications of gangliosides especially for GM3. During the course of study, we demonstrated the molecular pathogenesis of type 2 diabetes and insulin resistance focusing on the interaction between insulin receptor and gangliosides in membrane microdomains and propose a new concept: Life style-related diseases, such as type 2 diabetes, are a membrane microdomain disorder caused by aberrant expression of gangliosides. We also encountered an another interesting aspect indicating the indispensable role of gangliosides in auditory system. After careful behavioral examinations of SAT-I knockout mice, their hearing ability was seriously impaired with selective degeneration of the stereocilia of hair cells in the organ of Corti. This is the first observation demonstrating a direct link between gangliosides and hearing functions.
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Affiliation(s)
- Jin-ichi Inokuchi
- Division of Glycopathology, Institute of Molecular Biomembranes and Glycobiology, Tohoku Pharmaceutical University, Miyagi, Japan.
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170
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Oiticica J, Barboza-Junior LCM, Batissoco AC, Lezirovitz K, Mingroni-Netto RC, Haddad LA, Bento RF. Retention of progenitor cell phenotype in otospheres from guinea pig and mouse cochlea. J Transl Med 2010; 8:119. [PMID: 21087511 PMCID: PMC3001427 DOI: 10.1186/1479-5876-8-119] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2010] [Accepted: 11/18/2010] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Culturing otospheres from dissociated organ of Corti is an appropriate starting point aiming at the development of cell therapy for hair cell loss. Although guinea pigs have been widely used as an excellent experimental model for studying the biology of the inner ear, the mouse cochlea has been more suitable for yielding otospheres in vitro. The aim of this study was to compare conditions and outcomes of otosphere suspension cultures from dissociated organ of Corti of either mouse or guinea pig at postnatal day three (P3), and to evaluate the guinea pig as a potential cochlea donor for preclinical cell therapy. METHODS Organs of Corti were surgically isolated from P3 guinea pig or mouse cochlea, dissociated and cultivated under non-adherent conditions. Cultures were maintained in serum-free DMEM:F12 medium, supplemented with epidermal growth factor (EGF) plus either basic fibroblast growth factor (bFGF) or transforming growth factor alpha (TGFα). Immunofluorescence assays were conducted for phenotype characterization. RESULTS The TGFα group presented a number of spheres significantly higher than the bFGF group. Although mouse cultures yielded more cells per sphere than guinea pig cultures, sox2 and nestin distributed similarly in otosphere cells from both organisms. We present evidence that otospheres retain properties of inner ear progenitor cells such as self-renewal, proliferation, and differentiation into hair cells or supporting cells. CONCLUSIONS Dissociated guinea pig cochlea produced otospheres in vitro, expressing sox2 and nestin similarly to mouse otospheres. Our data is supporting evidence for the presence of inner ear progenitor cells in the postnatal guinea pig. However, there is limited viability for these cells in neonatal guinea pig cochlea when compared to the differentiation potential observed for the mouse organ of Corti at the same developmental stage.
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Affiliation(s)
- Jeanne Oiticica
- Department of Otolaryngology, Medical School, University of São Paulo, São Paulo, Brasil.
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171
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Shanidze N, Kim AH, Raphael Y, King WM. Eye-head coordination in the guinea pig I. Responses to passive whole-body rotations. Exp Brain Res 2010; 205:395-404. [PMID: 20686891 DOI: 10.1007/s00221-010-2374-4] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/02/2010] [Accepted: 07/15/2010] [Indexed: 11/28/2022]
Abstract
Vestibular reflexes act to stabilize the head and eyes in space during locomotion. Head stability is essential for postural control, whereas retinal image stability enhances visual acuity and may be essential for an animal to distinguish self-motion from that of an object in the environment. Guinea pig eye and head movements were measured during passive whole-body rotation in order to assess the efficacy of vestibular reflexes. The vestibulo-ocular reflex (VOR) produced compensatory eye movements with a latency of approximately 7 ms that compensated for 46% of head movement in the dark and only slightly more in the light (54%). Head movements, in response to abrupt body rotations, also contributed to retinal stability (21% in the dark; 25% in the light) but exhibited significant variability. Although compensatory eye velocity produced by the VOR was well correlated with head-in-space velocity, compensatory head-on-body speed and direction were variable and poorly correlated with body speed. The compensatory head movements appeared to be determined by passive biomechanical (e.g., inertial effects, initial tonus) and active mechanisms (the vestibulo-collic reflex or VCR). Chemically induced, bilateral lesions of the peripheral vestibular system abolished both compensatory head and eye movement responses.
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Affiliation(s)
- N Shanidze
- Department of Otolaryngology, University of Michigan, Ann Arbor, MI, USA.
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172
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Wang GP, Chatterjee I, Batts SA, Wong HT, Gong TW, Gong SS, Raphael Y. Notch signaling and Atoh1 expression during hair cell regeneration in the mouse utricle. Hear Res 2010; 267:61-70. [PMID: 20433915 PMCID: PMC2902641 DOI: 10.1016/j.heares.2010.03.085] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 12/11/2009] [Revised: 03/19/2010] [Accepted: 03/20/2010] [Indexed: 01/07/2023]
Abstract
The mammalian vestibular epithelium has a limited capacity for spontaneous hair cell regeneration. The mechanism underlying the regeneration is not well understood. Because the Notch signaling pathway mediates the formation of the sensory epithelial mosaic patterning during ear development, it may also play a role in hair cell regeneration in the mature mammalian vestibular epithelium after a lesion. To investigate the process of spontaneous regeneration in the vestibular epithelium vis-à-vis changes in Notch signaling, we induced a unilateral lesion by infusing streptomycin into the mouse posterior semicircular canal, and examined Notch signaling molecules and their mRNA expression levels by immunohistochemistry and quantitative real-time polymerase chain reaction (qRTPCR), respectively. We detected Jagged1 in supporting cells in both normal and lesioned utricles. Atoh1, a marker for early developing hair cells, was absent in the intact mature tissue, but re-appeared after the lesion. Many cells were either positive for both Atoh1 and myosin VIIa, or for one of them. qRTPCR data showed a post trauma decrease of Hes5 and an increase in Atoh1. Atoh1 up-regulation may either be a result of Hes5 down-regulation or mediated by another signaling pathway.
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Affiliation(s)
- Guo-Peng Wang
- Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
| | - Ishani Chatterjee
- Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Shelley A. Batts
- Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, MI 48109, USA
- Department of Otolaryngology-Head and Neck Surgery, Stanford University, 801 Welch Road, Stanford, CA 94305, USA
| | - Hiu Tung Wong
- Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Tzy-Wen Gong
- Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, MI 48109, USA
| | - Shu-Sheng Gong
- Department of Otolaryngology, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, Hubei 430022, China
- Department of Otolaryngology-Head and Neck Surgery, Beijing Tongren Hospital, Key Laboratory of Otolaryngology Head and Neck Surgery (Ministry of Education), Capital Medical University, Beijing 100730, China
| | - Yehoash Raphael
- Kresge Hearing Research Institute, Department of Otolaryngology, University of Michigan, Ann Arbor, MI 48109, USA
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173
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[Characterization of stem cells derived from the neonatal auditory sensory epithelium]. HNO 2010; 58:1056, 1058, 1060-6. [PMID: 20632158 DOI: 10.1007/s00106-010-2155-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/19/2022]
Abstract
BACKGROUND In contrast to regenerating hair cell-bearing organs of nonmammalian vertebrates the adult mammalian organ of Corti appears to have lost its ability to maintain stem cells. The result is a lack of regenerative ability and irreversible hearing loss following auditory hair cell death. Unexpectedly, the neonatal auditory sensory epithelium has recently been shown to harbor cells with stem cell features. The origin of these cells within the cochlea's sensory epithelium is unknown. MATERIAL AND METHODS We applied a modified neurosphere assay to identify stem cells within distinct subregions of the neonatal mouse auditory sensory epithelium. Sphere cells were characterized by multiple markers and morphologic techniques. RESULTS Our data reveal that both the greater and the lesser epithelial ridge contribute to the sphere-forming stem cell population derived from the auditory sensory epithelium. These self-renewing sphere cells express a variety of markers for neural and otic progenitor cells and mature inner ear cell types. CONCLUSION Stem cells can be isolated from specific regions of the auditory sensory epithelium. The distinct features of these cells imply a potential application in the development of a cell replacement therapy to regenerate the damaged sensory epithelium.
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174
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Shibata SB, Raphael Y. Future approaches for inner ear protection and repair. JOURNAL OF COMMUNICATION DISORDERS 2010; 43:295-310. [PMID: 20430401 PMCID: PMC2905731 DOI: 10.1016/j.jcomdis.2010.04.001] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2009] [Revised: 01/28/2010] [Accepted: 02/01/2010] [Indexed: 05/29/2023]
Abstract
UNLABELLED Health care professionals tending to patients with inner ear disease face inquiries about therapy options, including treatments that are being developed for future use but not yet available. The devastating outcome of sensorineural hearing loss, combined with the permanent nature of the symptoms, make these inquiries demanding and frequent. The vast information accessible online and the publicity for breakthroughs in research add to patient requests for access to advanced and innovative therapies, even before these are available for clinical use. This can sometimes be taxing on the health care provider who is in contact with the patients. Here we aim to equip the provider with information about some of the progress made for protective and reparative approaches for treating inner ears. LEARNING OUTCOMES (1) Readers will be able to explain why hearing loss is irreversible and common, (2) readers will be able to explain the importance of protective measures and the progress made in discovery and design of novel biological protective molecules, (3) readers will be able to describe reparative approaches currently under investigation (such as tissue engineering), the main difficulties in the design of such therapies and the major hurdles that remain for making novel technologies clinically viable, and (4) readers will be able to explain to their patients some of the progress in developing new treatments without making the promise of imminent clinical use. With this information, readers will be able to guide patients to make better choices for their treatment and to guide students toward research in this exciting field.
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Affiliation(s)
- Seiji B. Shibata
- Kresge Hearing Research Institute, Department of Otolaryngology, The University of Michigan, Ann Arbor, MI, 48109-5648, USA
| | - Yehoash Raphael
- Kresge Hearing Research Institute, Department of Otolaryngology, The University of Michigan, Ann Arbor, MI, 48109-5648, USA
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175
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Oshima K, Shin K, Diensthuber M, Peng AW, Ricci AJ, Heller S. Mechanosensitive hair cell-like cells from embryonic and induced pluripotent stem cells. Cell 2010; 141:704-16. [PMID: 20478259 DOI: 10.1016/j.cell.2010.03.035] [Citation(s) in RCA: 226] [Impact Index Per Article: 16.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2009] [Revised: 01/18/2010] [Accepted: 02/24/2010] [Indexed: 12/21/2022]
Abstract
Mechanosensitive sensory hair cells are the linchpin of our senses of hearing and balance. The inability of the mammalian inner ear to regenerate lost hair cells is the major reason for the permanence of hearing loss and certain balance disorders. Here, we present a stepwise guidance protocol starting with mouse embryonic stem and induced pluripotent stem cells, which were directed toward becoming ectoderm capable of responding to otic-inducing growth factors. The resulting otic progenitor cells were subjected to varying differentiation conditions, one of which promoted the organization of the cells into epithelial clusters displaying hair cell-like cells with stereociliary bundles. Bundle-bearing cells in these clusters responded to mechanical stimulation with currents that were reminiscent of immature hair cell transduction currents.
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Affiliation(s)
- Kazuo Oshima
- Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA
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176
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Abstract
Sensory hair cells of the inner ear are responsible for translating auditory or vestibular stimuli into electrical energy that can be perceived by the nervous system. Although hair cells are exquisitely mechanically sensitive, they can be easily damaged by excessive stimulation by ototoxic drugs and by the effects of aging. In mammals, auditory hair cells are never replaced, such that cumulative damage to the ear causes progressive and permanent deafness. In contrast, non-mammalian vertebrates are capable of replacing lost hair cells, which has led to efforts to understand the molecular and cellular basis of regenerative responses in different vertebrate species. In this review, we describe recent progress in understanding the limits to hair cell regeneration in mammals and discuss the obstacles that currently exist for therapeutic approaches to hair cell replacement.
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Affiliation(s)
- Andrew K Groves
- Department of Neuroscience, Baylor College of Medicine, BCM 295, 1 Baylor Plaza, Houston, TX 77030, USA.
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177
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Abstract
Cochlear hair cells transduce mechanical stimuli into electrical activity. The site of hair cell transduction is the hair bundle, an array of stereocilia with different height arranged in a staircase. Tip links connect the apex of each stereocilium to the side of its taller neighbor. The hair bundle and tip links of hair cells are susceptible to acoustic trauma and ototoxic drugs. It has been shown that hair cells in lower vertebrates and in the mammalian vestibular system may survive bundle loss and undergo self-repair of the stereocilia. Our goals were to determine whether cochlear hair cells could survive the trauma and whether the tip link and/or the hair bundle could be regenerated. We simulated the acoustic trauma-induced tip link damage or stereociliary loss by disrupting tip links or ablating the hair bundles in the cultured organ of Corti from neonatal gerbils. Hair-cell fate and stereociliary morphology and function were examined using confocal and scanning electron microscopies and electrophysiology. Most bundleless hair cells survived and developed for approximately 2 weeks. However, no spontaneous hair-bundle regeneration was observed. When tip links were ruptured, repair of tip links and restoration of mechanotransduction were observed in <24 h. Our study suggests that the dynamic nature of the hair cell's transduction apparatus is retained despite the fact that regeneration of the hair bundle is lost in mammalian cochlear hair cells.
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178
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Abstract
PURPOSE OF REVIEW This review will focus on 'self-repair' of the mammalian inner ear sensory epithelium, including recruiting the in-situ proliferation and differentiation of endogenous cells at the damaged site and the autologous transplantation RECENT FINDINGS Self-repair refers to a favorable structural and functional outcome of damaged inner ear sensory epithelium. Our advanced ability of manipulating the fate of inner ear sensory cells makes in-situ proliferation a possible candidate of hearing restoration. A practical alternative of the unavoidable immune rejection is to introduce autologous cells. Ependymal cells, induced pluripotent stem cells, and olfactory neuroepithelial cells have been recognized as promising sources, which will spur ongoing efforts to evaluate these new cell sources for cell replacement therapy. SUMMARY Further exploration of the innate advantages of in-situ proliferation and use of novel cell sources for autologous transplantation may serve as rehearsals for clinical trials in the near future.
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179
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Cheng CC, Wang DY, Kao MH, Chen JK. The growth-promoting effect of KGF on limbal epithelial cells is mediated by upregulation of ΔNp63α through the p38 pathway. J Cell Sci 2009; 122:4473-80. [DOI: 10.1242/jcs.054791] [Citation(s) in RCA: 38] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Corneal epithelial stem cells are thought to reside in the limbus, the transition zoon between cornea and conjunctiva. Keratinocyte growth factor (KGF) and hepatocyte growth factor (HGF) are two paracrine factors that regulate the proliferation, migration and differentiation of the limbal epithelial cells; however, the underlying mechanisms are still poorly understood. In an ex vivo limbal explant culture, we found that KGF is a more potent growth stimulator for the epithelial outgrowth than HGF. Immunofluorescence studies of the epithelial outgrowth from cells treated with HGF or KGF showed similar expression patterns of keratin-3 and keratin-14. Interestingly, p63 was highly expressed in KGF-treated limbal epithelial sheets but not in those treated with HGF. Kinase inhibitor studies showed that induction of ΔNp63α expression by KGF is mediated via the p38 pathway. The effect of KGF on limbal epithelial outgrowth was significantly reduced when endogenous ΔNp63α was suppressed, suggesting that KGF-induced limbal epithelial outgrowth is dependent on the expression of ΔNp63α. Our findings strongly suggest that limbal keratocytes regulate limbal epithelial cell growth and differentiation through a KGF paracrine loop, with ΔNp63α expression as one of the downstream targets.
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Affiliation(s)
- Chien-Chia Cheng
- Department of Physiology, College of Medicine, Chang Gung University, Kweishan, Taoyuan 333, Taiwan
| | - Der-Yuan Wang
- Section of Blood Products & IVDs, Drug Biology Division, Bureau of Food and Drug Analysis, Department of Health, Taiwan
| | - Ming-Hui Kao
- Section of Blood Products & IVDs, Drug Biology Division, Bureau of Food and Drug Analysis, Department of Health, Taiwan
| | - Jan-Kan Chen
- Department of Physiology, College of Medicine, Chang Gung University, Kweishan, Taoyuan 333, Taiwan
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180
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Hartman BH, Basak O, Nelson BR, Taylor V, Bermingham-McDonogh O, Reh TA. Hes5 expression in the postnatal and adult mouse inner ear and the drug-damaged cochlea. J Assoc Res Otolaryngol 2009; 10:321-40. [PMID: 19373512 PMCID: PMC2757554 DOI: 10.1007/s10162-009-0162-2] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/14/2008] [Accepted: 02/09/2009] [Indexed: 11/30/2022] Open
Abstract
The Notch signaling pathway is known to have multiple roles during development of the inner ear. Notch signaling activates transcription of Hes5, a homologue of Drosophila hairy and enhancer of split, which encodes a basic helix-loop-helix transcriptional repressor. Previous studies have shown that Hes5 is expressed in the cochlea during embryonic development, and loss of Hes5 leads to overproduction of auditory and vestibular hair cells. However, due to technical limitations and inconsistency between previous reports, the precise spatial and temporal pattern of Hes5 expression in the postnatal and adult inner ear has remained unclear. In this study, we use Hes5-GFP transgenic mice and in situ hybridization to report the expression pattern of Hes5 in the inner ear. We find that Hes5 is expressed in the developing auditory epithelium of the cochlea beginning at embryonic day 14.5 (E14.5), becomes restricted to a particular subset of cochlear supporting cells, is downregulated in the postnatal cochlea, and is not present in adults. In the vestibular system, we detect Hes5 in developing supporting cells as early as E12.5 and find that Hes5 expression is maintained in some adult vestibular supporting cells. In order to determine the effect of hair cell damage on Notch signaling in the cochlea, we damaged cochlear hair cells of adult Hes5-GFP mice in vivo using injection of kanamycin and furosemide. Although outer hair cells were killed in treated animals and supporting cells were still present after damage, supporting cells did not upregulate Hes5-GFP in the damaged cochlea. Therefore, absence of Notch-Hes5 signaling in the normal and damaged adult cochlea is correlated with lack of regeneration potential, while its presence in the neonatal cochlea and adult vestibular epithelia is associated with greater capacity for plasticity or regeneration in these tissues; which suggests that this pathway may be involved in regulating regenerative potential.
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Affiliation(s)
- Byron H. Hartman
- />Department of Biological Structure, University of Washington, Box 357420, Seattle, WA 98195 USA
| | - Onur Basak
- />Department of Molecular Embryology, Max-Planck Institute of Immunobiology, Stubeweg 51, 79108 Freiburg, Germany
| | - Branden R. Nelson
- />Department of Biological Structure, University of Washington, Box 357420, Seattle, WA 98195 USA
| | - Verdon Taylor
- />Department of Molecular Embryology, Max-Planck Institute of Immunobiology, Stubeweg 51, 79108 Freiburg, Germany
| | - Olivia Bermingham-McDonogh
- />Department of Biological Structure, University of Washington, Box 357420, Seattle, WA 98195 USA
- />Virginia Merrill Bloedel Hearing Research Center at the University of Washington, Seattle, WA 98195 USA
| | - Thomas A. Reh
- />Department of Biological Structure, University of Washington, Box 357420, Seattle, WA 98195 USA
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181
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Horner KC, Troadec JD, Dallaporta M, Pio J. Effect of chronic estradiol administration on vimentin and GFAP immunohistochemistry within the inner ear. Neurobiol Dis 2009; 35:201-8. [DOI: 10.1016/j.nbd.2009.04.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Revised: 04/17/2009] [Accepted: 04/21/2009] [Indexed: 11/15/2022] Open
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182
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Yamane H, Nakagawa T, Iguchi H, Shibata S, Takayama M, Nishimura K, Nakai Y. In vivoRegeneration of Vestibular Hair Cells of Guinea Pig. Acta Otolaryngol 2009. [DOI: 10.3109/00016489509125220] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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183
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Abstract
Hearing loss is a global health problem with profound socioeconomic impact. We contend that acquired hearing loss is mainly a modern disorder caused by man-made noise and modern drugs, among other causes. These factors, combined with increasing lifespan, have exposed a deficit in cochlear self-regeneration that was irrelevant for most of mammalian evolution. Nevertheless, the mammalian cochlea has evolved from phylogenetically older structures, which do have the capacity for self-repair. Moreover, nonmammalian vertebrates can regenerate auditory hair cells that restore sensory function. We will offer a critical perspective on recent advances in stem cell biology, gene therapy, cell cycle regulation and pharmacotherapeutics to define and validate regenerative medical interventions for mammalian hair cell loss. Although these advances are promising, we are only beginning to fully appreciate the complexity of the many challenges that lie ahead.
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Affiliation(s)
- John V Brigande
- Department of Otolaryngology, Oregon Hearing Research Center, Oregon Health & Science University, Portland, Oregon, USA
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184
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Diensthuber M, Oshima K, Heller S. Stem/progenitor cells derived from the cochlear sensory epithelium give rise to spheres with distinct morphologies and features. J Assoc Res Otolaryngol 2009; 10:173-90. [PMID: 19247714 DOI: 10.1007/s10162-009-0161-3] [Citation(s) in RCA: 56] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2008] [Accepted: 02/05/2009] [Indexed: 11/25/2022] Open
Abstract
Nonmammalian vertebrates regenerate lost sensory hair cells by means of asymmetric division of supporting cells. Inner ear or lateral line supporting cells in birds, amphibians, and fish consequently serve as bona fide stem cells resulting in high regenerative capacity of hair cell-bearing organs. Hair cell regeneration does not happen in the mammalian cochlea, but cells with proliferative capacity can be isolated from the neonatal cochlea. These cells have the ability to form clonal floating colonies, so-called spheres, when cultured in nonadherent conditions. We noticed that the sphere population derived from mouse cochlear sensory epithelium cells was heterogeneous, consisting of morphologically distinct sphere types, hereby classified as solid, transitional, and hollow. Cochlear sensory epithelium-derived stem/progenitor cells initially give rise to small solid spheres, which subsequently transition into hollow spheres, a change that is accompanied by epithelial differentiation of the majority of sphere cells. Only solid spheres, and to a lesser extent, transitional spheres, appeared to harbor self-renewing stem cells, whereas hollow spheres could not be consistently propagated. Solid spheres contained significantly more rapidly cycling Pax-2-expressing presumptive otic progenitor cells than hollow spheres. Islet-1, which becomes upregulated in nascent sensory patches, was also more abundant in solid than in hollow spheres. Likewise, hair cell-like cells, characterized by the expression of multiple hair cell markers, differentiated in significantly higher numbers in cell populations derived from solid spheres. We conclude that cochlear sensory epithelium cell populations initially give rise to small solid spheres that have self-renewing capacity before they subsequently convert into hollow spheres, a process that is accompanied by loss of stemness and reduced ability to spontaneously give rise to hair cell-like cells. Solid spheres might, therefore, represent the most suitable sphere type for cell-based assays or animal model transplantation studies aimed at development of cell replacement therapies.
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Affiliation(s)
- Marc Diensthuber
- Departments of Otolaryngology-Head & Neck Surgery and Molecular & Cellular Physiology, School of Medicine, Stanford University, 801 Welch Road, Stanford, CA 94305-5739, USA
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185
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Huang M, Sage C, Li H, Xiang M, Heller S, Chen ZY. Diverse expression patterns of LIM-homeodomain transcription factors (LIM-HDs) in mammalian inner ear development. Dev Dyn 2009; 237:3305-12. [PMID: 18942141 DOI: 10.1002/dvdy.21735] [Citation(s) in RCA: 31] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023] Open
Abstract
LIM-homeodomain transcription factors (LIM-HDs) are essential in tissue patterning and differentiation. But their expression patterns in the inner ear are largely unknown. Here we report on a study of twelve LIM-HDs, by their tempo-spatial patterns that imply distinct yet overlapping roles, in the developing mouse inner ear. Expression of Lmx1a and Isl1 begins in the otocyst stage, with Lmx1a exclusively in the non-sensory and Isl1 in the prosensory epithelia. The second wave of expression at E12.5 includes Lhx3, 5, 9, Isl2, and Lmx1b in the differentiating sensory epithelia with cellular specificities. With the exception of Lmx1a and Lhx3, all LIM-HDs are expressed in ganglion neurons. Expression of multiple LIM-HDs within a cell type suggests their redundant function.
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Affiliation(s)
- Mingqian Huang
- Eaton-Peabody Laboratory, Massachusetts Eye and Ear Infirmary and Department of Otology and Laryngology, Harvard Medical School, Boston, Massachusetts 02114, USA
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186
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Kawamoto K, Izumikawa M, Beyer LA, Atkin GM, Raphael Y. Spontaneous hair cell regeneration in the mouse utricle following gentamicin ototoxicity. Hear Res 2008; 247:17-26. [PMID: 18809482 DOI: 10.1016/j.heares.2008.08.010] [Citation(s) in RCA: 92] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/22/2008] [Accepted: 08/22/2008] [Indexed: 10/21/2022]
Abstract
Whereas most epithelial tissues turn-over and regenerate after a traumatic lesion, this restorative ability is diminished in the sensory epithelia of the inner ear; it is absent in the cochlea and exists only in a limited capacity in the vestibular epithelium. The extent of regeneration in vestibular hair cells has been characterized for several mammalian species including guinea pig, rat, and chinchilla, but not yet in mouse. As the fundamental model species for investigating hereditary disease, the mouse can be studied using a wide variety of genetic and molecular tools. To design a mouse model for vestibular hair cell regeneration research, an aminoglycoside-induced method of complete hair cell elimination was developed in our lab and applied to the murine utricle. Loss of utricular hair cells was observed using scanning electron microscopy, and corroborated by a loss of fluorescent signal in utricles from transgenic mice with GFP-positive hair cells. Regenerative capability was characterized at several time points up to six months following insult. Using scanning electron microscopy, we observed that as early as two weeks after insult, a few immature hair cells, demonstrating the characteristic immature morphology indicative of regeneration, could be seen in the utricle. As time progressed, larger numbers of immature hair cells could be seen along with some mature cells resembling surface morphology of type II hair cells. By six months post-lesion, numerous regenerated hair cells were present in the utricle, however, neither their number nor their appearance was normal. A BrdU assay suggested that at least some of the regeneration of mouse vestibular hair cells involved mitosis. Our results demonstrate that the vestibular sensory epithelium in mice can spontaneously regenerate, elucidate the time course of this process, and identify involvement of mitosis in some cases. These data establish a road map of the murine vestibular regenerative process, which can be used for elucidating the molecular events that govern this process.
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Affiliation(s)
- Kohei Kawamoto
- Department of Otolaryngology, Kansai Medical University, 10-15 Fumizono-cho, Moriguchi, Osaka 570-8506, Japan
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187
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Cotanche DA. Genetic and pharmacological intervention for treatment/prevention of hearing loss. JOURNAL OF COMMUNICATION DISORDERS 2008; 41:421-443. [PMID: 18455177 PMCID: PMC2574670 DOI: 10.1016/j.jcomdis.2008.03.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/04/2008] [Accepted: 03/12/2008] [Indexed: 05/26/2023]
Abstract
UNLABELLED Twenty years ago it was first demonstrated that birds could regenerate their cochlear hair cells following noise damage or aminoglycoside treatment. An understanding of how this structural and functional regeneration occurred might lead to the development of therapies for treatment of sensorineural hearing loss in humans. Recent experiments have demonstrated that noise exposure and aminoglycoside treatment lead to apoptosis of the hair cells. In birds, this programmed cell death induces the adjacent supporting cells to undergo regeneration to replace the lost hair cells. Although hair cells in the mammalian cochlea undergo apoptosis in response to noise damage and ototoxic drug treatment, the supporting cells do not possess the ability to undergo regeneration. However, current experiments on genetic manipulation, gene therapy, and stem cell transplantation suggest that regeneration in the mammalian cochlea may eventually be possible and may 1 day provide a therapeutic tool for hearing loss in humans. LEARNING OUTCOMES The reader should be able to: (1) Describe the anatomy of the avian and mammalian cochlea, identify the individual cell types in the organ of Corti, and distinguish major features that participate in hearing function, (2) Demonstrate a knowledge of how sound damage and aminoglycoside poisoning induce apoptosis of hair cells in the cochlea, (3) Define how hair cell loss in the avian cochlea leads to regeneration of new hair cells and distinguish this from the mammalian cochlea where there is no regeneration following damage, and (4) Interpret the potential for new approaches, such as genetic manipulation, gene therapy and stem cell transplantation, could provide a therapeutic approach to hair cell loss in the mammalian cochlea.
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MESH Headings
- Aminoglycosides/toxicity
- Animals
- Apoptosis/drug effects
- Apoptosis/genetics
- Apoptosis/physiology
- Birds
- Cell Proliferation/drug effects
- Genetic Therapy
- Guinea Pigs
- Hair Cells, Auditory/drug effects
- Hair Cells, Auditory/pathology
- Hair Cells, Auditory/physiology
- Hearing Loss, Noise-Induced/pathology
- Hearing Loss, Noise-Induced/physiopathology
- Hearing Loss, Noise-Induced/therapy
- Hearing Loss, Sensorineural/pathology
- Hearing Loss, Sensorineural/physiopathology
- Hearing Loss, Sensorineural/therapy
- Humans
- Mice
- Mice, Knockout
- Microscopy, Confocal
- Nerve Regeneration/drug effects
- Nerve Regeneration/genetics
- Nerve Regeneration/physiology
- Organ of Corti/drug effects
- Organ of Corti/pathology
- Organ of Corti/physiopathology
- Stem Cell Transplantation
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Affiliation(s)
- Douglas A Cotanche
- Laboratory of Cellular and Molecular Hearing Research, Department of Otolaryngology, Children's Hospital Boston, Boston, MA, USA.
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188
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Edge AS, Chen ZY. Hair cell regeneration. Curr Opin Neurobiol 2008; 18:377-82. [PMID: 18929656 PMCID: PMC5653255 DOI: 10.1016/j.conb.2008.10.001] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2008] [Revised: 09/30/2008] [Accepted: 10/02/2008] [Indexed: 01/03/2023]
Abstract
The mammalian inner ear largely lacks the capacity to regenerate hair cells, the sensory cells required for hearing and balance. Recent studies in both lower vertebrates and mammals have uncovered genes and pathways important in hair cell development and have suggested ways that the sensory epithelia could be manipulated to achieve hair cell regeneration. These approaches include the use of inner ear stem cells, transdifferentiation of nonsensory cells, and induction of a proliferative response in the cells that can become hair cells.
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Affiliation(s)
- Albert Sb Edge
- Department of Otology and Laryngology, Harvard Medical School, Boston, MA 02115, United States.
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189
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Hua Y, Xiao–wei C, Zhi–qiang G. Recent progresses in stem cell research and hearing restoration. J Otol 2008. [DOI: 10.1016/s1672-2930(08)50001-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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190
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Advances in Molecular and Cellular Therapies for Hearing Loss. Mol Ther 2008; 16:224-236. [DOI: 10.1038/sj.mt.6300351] [Citation(s) in RCA: 59] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2007] [Accepted: 10/10/2007] [Indexed: 02/07/2023] Open
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191
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Ying W, Min-min D, Hai-bo Y, Song-tao G. In vitro Differentiation of Adipose-Derived Stem Cells into Hair Cell-Like Cells in Guinea Pigs. J Otol 2007. [DOI: 10.1016/s1672-2930(07)50020-6] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022] Open
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192
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Ozeki H, Oshima K, Senn P, Kurihara H, Kaga K. Development and regeneration of hair cells. Acta Otolaryngol 2007:38-44. [PMID: 18340569 DOI: 10.1080/03655230701597200] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022]
Abstract
The vertebrate inner ear is derived from the otic placode and undergoes a complicated series of morphogenetic processes to differentiate into an elaborate structure harboring mechanosensory epithelia featuring hair cells, the mechanoreceptors of hearing and balance. Recently, the principal mechanisms producing hair cells and the key molecules involved in their fate determination and differentiation have been gradually unveiled. The in-depth understanding of hair cell development is consequently providing clues to strategies for mammalian hair cell regeneration. Among them, the identification and characterization of progenitor cells for the hair cell lineage, which is just emerging, is of particular interest. Herein, we review the molecular mechanisms of inner ear development with particular focus on perspectives for hair cell regeneration.
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193
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Kharlamova A, Aarts NL. A Review of Past and Present Hair Cell Regeneration Techniques. ACTA ACUST UNITED AC 2007. [DOI: 10.1044/cicsd_34_f_134] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
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194
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Corwin JT, Warchol ME, Saffer LD, Finley JE, Gu R, Lamber PR. Growth factors as potential drugs for the sensory epithelia of the ear. CIBA FOUNDATION SYMPOSIUM 2007; 196:167-82; discussion 182-7. [PMID: 8866134 DOI: 10.1002/9780470514863.ch12] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/02/2023]
Abstract
The highly ordered structures of the hearing and balance organs of vertebrate ears go through a coordinated sequence of cellular and morphogenetic events. It is to be expected that protein growth factors and other extracellular signals will regulate many events during embryonic development of the ear, including the induction of the ear, the specific induction of sensory epithelia, the proliferation of the cells that form the sensory epithelia, the differentiation of the sensory and supporting cells, and the attraction and maintenance of innervation. After embryonic development, growth factors will support cell survival and innervation of new sensory cells. In damaged sensory epithelia, supplementation of the normal growth factors in these tissues has the potential to influence cellular responses to trauma, to reduce cell death and to promote the replacement of dead cells through renewed proliferation and differentiation, so as to improve hearing and balance health via preventive and restorative treatments. Assessment of the influences of specific growth factors on the sensory epithelia of vertebrate ears is at an early stage: this paper provides a brief account of what we know from studies of normal and experimentally manipulated epithelia, discusses the current questions and suggests directions for future studies.
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Affiliation(s)
- J T Corwin
- Department of Otolaryngology, Head and Neck Surgery, University of Virginia School of Medicine, Charlottesville 22908, USA
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195
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Breuskin I, Bodson M, Thelen N, Thiry M, Nguyen L, Belachew S, Lefebvre PP, Malgrange B. Strategies to regenerate hair cells: identification of progenitors and critical genes. Hear Res 2007; 236:1-10. [PMID: 17920797 DOI: 10.1016/j.heares.2007.08.007] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/05/2007] [Revised: 08/03/2007] [Accepted: 08/12/2007] [Indexed: 01/13/2023]
Abstract
Deafness commonly results from a lesion of the sensory cells and/or of the neurons of the auditory part of the inner ear. There are currently no treatments designed to halt or reverse the progression of hearing loss. A key goal in developing therapy for sensorineural deafness is the identification of strategies to replace lost hair cells. In amphibians and birds, a spontaneous post-injury regeneration of all inner ear sensory hair cells occurs. In contrast, in the mammalian cochlea, hair cells are only produced during embryogenesis. Many studies have been carried out in order to demonstrate the persistence of endogenous progenitors. The present review is first focused on the occurrence of spontaneous supernumerary hair cells and on nestin positive precursors found in the organ of Corti. A second approach to regenerating hair cells would be to find genes essential for their differentiation. This review will also focus on critical genes for embryonic hair cell formation such as the cell cycle related proteins, the Atoh1 gene and the Notch signaling pathway. Understanding mechanisms that underlie hair cell production is an essential prerequisite to defining therapeutic strategies to regenerate hair cells in the mature inner ear.
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Affiliation(s)
- Ingrid Breuskin
- Center for Cellular and Molecular Neurosciences, Developmental Neurobiology Unit, University of Liege, 4000 Liege, Belgium
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196
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Xu H, Chen L, Baldini A. In vivo genetic ablation of the periotic mesoderm affects cell proliferation survival and differentiation in the cochlea. Dev Biol 2007; 310:329-40. [PMID: 17825816 PMCID: PMC2223065 DOI: 10.1016/j.ydbio.2007.08.006] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2007] [Revised: 07/24/2007] [Accepted: 08/01/2007] [Indexed: 02/08/2023]
Abstract
Tbx1 is required for ear development in humans and mice. Gene manipulation in the mouse has discovered multiple consequences of loss of function on early development of the inner ear, some of which are attributable to a cell autonomous role in maintaining cell proliferation of epithelial progenitors of the cochlear and vestibular apparata. However, ablation of the mesodermal domain of the gene also results in severe but more restricted abnormalities. Here we show that Tbx1 has a dynamic expression during late development of the ear, in particular, is expressed in the sensory epithelium of the vestibular organs but not of the cochlea. Vice versa, it is expressed in the condensed mesenchyme that surrounds the cochlea but not in the one that surrounds the vestibule. Loss of Tbx1 in the mesoderm disrupts this peri-cochlear capsule by strongly reducing the proliferation of mesenchymal cells. The organogenesis of the cochlea, which normally occurs inside the capsule, was dramatically affected in terms of growth of the organ, as well as proliferation, differentiation and survival of its epithelial cells. This model provides a striking demonstration of the essential role played by the periotic mesenchyme in the organogenesis of the cochlea.
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Affiliation(s)
- Huansheng Xu
- Institute of Biosciences and Technology, Texas A&M University Health Sciences Center, Houston, TX 77030
| | - Li Chen
- Institute of Biosciences and Technology, Texas A&M University Health Sciences Center, Houston, TX 77030
- Program in Cardiovascular Sciences, Baylor College of Medicine, Houston, TX 77030
| | - Antonio Baldini
- Institute of Biosciences and Technology, Texas A&M University Health Sciences Center, Houston, TX 77030
- Program in Cardiovascular Sciences, Baylor College of Medicine, Houston, TX 77030
- Telethon Institute of Genetics and Medicine, Naples, Italy
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197
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Gu R, Montcouquiol M, Marchionni M, Corwin JT. Proliferative responses to growth factors decline rapidly during postnatal maturation of mammalian hair cell epithelia. Eur J Neurosci 2007; 25:1363-72. [PMID: 17425563 DOI: 10.1111/j.1460-9568.2007.05414.x] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Millions of lives are affected by hearing and balance deficits that arise as a consequence of sensory hair cell loss. Those deficits affect mammals permanently, but hearing and balance recover in nonmammals after epithelial supporting cells divide and produce replacement hair cells. Hair cells are not effectively replaced in mammals, but balance epithelia cultured from the ears of rodents and adult humans can respond to hair cell loss with low levels of supporting cell proliferation. We have sought to stimulate vestibular proliferation; and we report here that treatment with glial growth factor 2 (rhGGF2) yields a 20-fold increase in cell proliferation within sheets of pure utricular hair cell epithelium explanted from adult rats into long-term culture. In epithelia from neonates, substantially greater proliferation responses are evoked by rhGGF2 alone, insulin alone and to a lesser degree by serum even during short-term cultures, but all these responses progressively decline during the first 2 weeks of postnatal maturation. Thus, sheets of utricular epithelium from newborn rats average > 40% labelling when cultured for 72 h with bromo-deoxyuridine (BrdU) and either rhGGF2 or insulin. Those from 5- and 6-day-olds average 8-15%, 12-day-olds average < 1% and after 72 h there is little or no labelling in epithelia from 27- and 35-day-olds. These cells are the mammalian counterparts of the progenitors that produce replacement hair cells in nonmammals, so the postnatal quiescence described here is likely to be responsible for at least part of the mammalian ear's unique vulnerability to permanent sensory deficits.
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Affiliation(s)
- Rende Gu
- Department of Neuroscience, University of Virginia, School of Medicine, HSC Box 801392, MR-4 Bldg., Rm 5150, Lane Road, Charlottesville, VA 22908, USA
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198
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Hawkins RD, Bashiardes S, Powder KE, Sajan SA, Bhonagiri V, Alvarado DM, Speck J, Warchol ME, Lovett M. Large scale gene expression profiles of regenerating inner ear sensory epithelia. PLoS One 2007; 2:e525. [PMID: 17565378 PMCID: PMC1888727 DOI: 10.1371/journal.pone.0000525] [Citation(s) in RCA: 62] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2006] [Accepted: 05/23/2007] [Indexed: 12/29/2022] Open
Abstract
Loss of inner ear sensory hair cells (HC) is a leading cause of human hearing loss and balance disorders. Unlike mammals, many lower vertebrates can regenerate these cells. We used cross-species microarrays to examine this process in the avian inner ear. Specifically, changes in expression of over 1700 transcription factor (TF) genes were investigated in hair cells of auditory and vestibular organs following treatment with two different damaging agents and regeneration in vitro. Multiple components of seven distinct known signaling pathways were clearly identifiable: TGFbeta, PAX, NOTCH, WNT, NFKappaB, INSULIN/IGF1 and AP1. Numerous components of apoptotic and cell cycle control pathways were differentially expressed, including p27(KIP) and TFs that regulate its expression. A comparison of expression trends across tissues and treatments revealed identical patterns of expression that occurred at identical times during regenerative proliferation. Network analysis of the patterns of gene expression in this large dataset also revealed the additional presence of many components (and possible network interactions) of estrogen receptor signaling, circadian rhythm genes and parts of the polycomb complex (among others). Equal numbers of differentially expressed genes were identified that have not yet been placed into any known pathway. Specific time points and tissues also exhibited interesting differences: For example, 45 zinc finger genes were specifically up-regulated at later stages of cochlear regeneration. These results are the first of their kind and should provide the starting point for more detailed investigations of the role of these many pathways in HC recovery, and for a description of their possible interactions.
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Affiliation(s)
- R. David Hawkins
- Division of Human Genetics, Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Stavros Bashiardes
- Division of Human Genetics, Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Kara E. Powder
- Division of Human Genetics, Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Samin A. Sajan
- Division of Human Genetics, Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Veena Bhonagiri
- Division of Human Genetics, Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - David M. Alvarado
- Division of Human Genetics, Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Judith Speck
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Mark E. Warchol
- Department of Otolaryngology, Washington University School of Medicine, St. Louis, Missouri, United States of America
| | - Michael Lovett
- Division of Human Genetics, Department of Genetics, Washington University School of Medicine, St. Louis, Missouri, United States of America
- * To whom correspondence should be addressed. E-mail:
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199
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Schirmer M, Kaiser A, Lessenich A, Lindemann S, Fedrowitz M, Gernert M, Löscher W. Auditory and vestibular defects and behavioral alterations after neonatal administration of streptomycin to Lewis rats: Similarities and differences to the circling (ci2/ci2) Lewis rat mutant. Brain Res 2007; 1155:179-95. [PMID: 17493596 DOI: 10.1016/j.brainres.2007.04.012] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2007] [Revised: 04/04/2007] [Accepted: 04/06/2007] [Indexed: 11/28/2022]
Abstract
The clinical usefulness of aminoglycoside antibiotics is limited by their ototoxicity. In rodents, damage to the inner ear is often associated with rotational behavior and locomotor hyperactivity reminiscent of such behaviors resulting from an imbalance of forebrain dopamine systems. Based on previous observations in the circling (ci2/ci2) Lewis (LEW) rat mutant, a spontaneous mutation leading to hair cell loss, deafness, impairment of vestibular functions, lateralized circling, hyperactivity and alterations in the nigrostriatal dopamine system, we have recently hypothesized that vestibular defects during postnatal development, independent of whether induced or inherited, lead to secondary changes in the dopaminergic system within the basal ganglia, which would be a likely explanation for the typical behavioral phenotype seen in such models. In the present study, we directly compared the phenotype induced by streptomycin in LEW rats with that of the ci2 LEW rat mutant. For this purpose, we treated neonatal LEW rats over 3 weeks by streptomycin, which induced bilateral degeneration of cochlear and vestibular hair cells. Following this treatment period, the behavioral syndrome of the streptomycin-treated animals, including the lateralized rotational behavior, was almost indistinguishable from that of ci2 mutant rats. However, in contrast to the ci2 mutant rat, all alterations, except the hearing loss, were only transient, disappearing between 7 and 24 weeks following treatment. In conclusion, in line with our hypothesis, vestibular defects induced in normal LEW rats led to the same phenotypic behavior as the inherited vestibular defect of ci2 mutant rats. However, with increasing time for recovery, adaptation to the vestibular impairment developed in streptomycin-treated rats, while all deficits persisted in the mutant animals. At least in part, the transient nature of the abnormal behaviors resulting from treatment with streptomycin could be explained by adaptation to the vestibular impairment by the use of visual cues, which is not possible in ci2 rats because of progressive retinal degeneration in these mutants. Although further experiments are needed to prove this hypothesis, the present study shows that direct comparisons between these two models serve to understand the mechanisms underlying the complex behavioral phenotype in rodents with vestibular defects and how these defects are compensated.
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Affiliation(s)
- Marko Schirmer
- Department of Pharmacology, Toxicology, and Pharmacy, University of Veterinary Medicine Hannover, Bünteweg 17, Hannover, Germany
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200
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Staecker H, Praetorius M, Baker K, Brough DE. Vestibular hair cell regeneration and restoration of balance function induced by math1 gene transfer. Otol Neurotol 2007; 28:223-31. [PMID: 17255891 DOI: 10.1097/mao.0b013e31802b3225] [Citation(s) in RCA: 111] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
HYPOTHESIS Delivery of math1 using an adenovector (Admath1.11D) results in vestibular hair cell regeneration and recovery of balance function in ototoxin-treated adult mice. BACKGROUND Loss of peripheral vestibular function is associated with disease processes such as vestibular neuronitis, aminoglycoside ototoxicity, and aging. Loss of vestibular hair cells is one of the mechanisms underlying balance dysfunction in all of these disorders. Currently, recovery from these diseases relies on central vestibular compensation rather than on local tissue recovery. Overexpression of the mammalian atonal homologue math1 has been demonstrated to induce generation of hair cells in neonatal organ of Corti cultures and in the guinea pig cochlea in vivo and could thus provide an approach to local tissue recovery. METHODS Admath1.11D was applied to cultures of aminoglycoside-treated macular organs or in vivo in a mouse aminoglycoside ototoxicity model. Outcome measures included histologic examination, immunohistochemistry, swim testing, and evaluation of the horizontal vestibulo-ocular reflex. RESULTS Delivery of math1 resulted in the generation of vestibular hair cells in vitro after aminoglycoside-mediated loss of hair cells. Math1-treated mice showed recovery of the vestibular neuroepithelium within 8 weeks after Admath1.11D treatment. Assessment of animals after vector infusion demonstrated a recovery of vestibular function compared with aminoglycoside-only-treated mice. CONCLUSION Molecular replacement of math1 may provide a therapeutic means of restoring vestibular function related to vestibular hair cell loss.
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Affiliation(s)
- Hinrich Staecker
- Otolaryngology Head and Neck Surgery, University of Kansas School of Medicine, Kansas City, Kansas 66160, USA.
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