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Gene therapy development in hearing research in China. Gene Ther 2020; 27:349-359. [PMID: 32681137 DOI: 10.1038/s41434-020-0177-1] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2020] [Revised: 06/13/2020] [Accepted: 07/08/2020] [Indexed: 12/15/2022]
Abstract
Sensorineural hearing loss, the most common form of hearing impairment, is mainly attributable to genetic mutations or acquired factors, such as aging, noise exposure, and ototoxic drugs. In the field of gene therapy, advances in genetic and physiological studies and profound increases in knowledge regarding the underlying mechanisms have yielded great progress in terms of restoring the auditory function in animal models of deafness. Nonetheless, many challenges associated with the translation from basic research to clinical therapies remain to be overcome before a total restoration of auditory function can be expected. In recent years, Chinese research teams have promoted various developmental efforts in this field, including gene sequencing to identify additional potential loci that cause deafness, studies to elucidate the underlying molecular mechanisms, and research to optimize vectors and delivery routes. In this review, we summarize the state of the field and focus mainly on the progress of gene therapy in animal model studies and the optimization of therapeutic strategies in China.
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Huang YB, Ma R, Yang JM, Han Z, Cong N, Gao Z, Ren D, Wang J, Chi FL. Cell proliferation during hair cell regeneration induced by Math 1 in vestibular epithelia in vitro. Neural Regen Res 2018; 13:497-501. [PMID: 29623936 PMCID: PMC5900514 DOI: 10.4103/1673-5374.228734] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2022] Open
Abstract
Hair cell regeneration is the fundamental method of correcting hearing loss and balance disorders caused by hair cell damage or loss. How to promote hair cell regeneration is a hot focus in current research. In mammals, cochlear hair cells cannot be regenerated and few vestibular hair cells can be renewed through spontaneous regeneration. However, Math1 gene transfer allows a few inner ear cells to be transformed into hair cells in vitro or in vivo. Hair cells can be renewed through two possible means in birds: supporting cell differentiation and transdifferentiation with or without cell division. Hair cell regeneration is strongly associated with cell proliferation. Therefore, this study explored the relationship between Math1-induced vestibular hair cell regeneration and cell division in mammals. The mouse vestibule was isolated to harvest vestibular epithelial cells. Ad-Math1-enhanced green fluorescent protein (EGFP) was used to track cell division during hair cell transformation. 5-Bromo-2′-deoxyuridine (BrdU) was added to track cell proliferation at various time points. Immunocytochemistry was utilized to determine cell differentiation and proliferation. Results demonstrated that when epithelial cells were in a higher proliferative stage, more of these cells differentiated into hair cells by Math1 gene transfer. However, in the low proliferation stage, no BrdU-positive cells were seen after Math1 gene transfer. Cell division always occurred before Math1 transfection but not during or after Math1 transfection, when cells were labeled with BrdU before and after Ad-Math1-EGFP transfection. These results confirm that vestibular epithelial cells with high proliferative potential can differentiate into new hair cells by Math1 gene transfer, but this process is independent of cell proliferation.
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Affiliation(s)
- Yi-Bo Huang
- Department of Otology and Skull Base Surgery, EYE & ENT Hospital of Fudan University; Shanghai Clinical Medical Center of Hearing Medicine; Key Laboratory of Hearing Medicine, Ministry of Health, Shanghai, China
| | - Rui Ma
- Department of Otology and Skull Base Surgery, EYE & ENT Hospital of Fudan University; Shanghai Clinical Medical Center of Hearing Medicine; Key Laboratory of Hearing Medicine, Ministry of Health, Shanghai, China
| | - Juan-Mei Yang
- Department of Otology and Skull Base Surgery, EYE & ENT Hospital of Fudan University; Shanghai Clinical Medical Center of Hearing Medicine; Key Laboratory of Hearing Medicine, Ministry of Health, Shanghai, China
| | - Zhao Han
- Department of Otology and Skull Base Surgery, EYE & ENT Hospital of Fudan University; Shanghai Clinical Medical Center of Hearing Medicine; Key Laboratory of Hearing Medicine, Ministry of Health, Shanghai, China
| | - Ning Cong
- Department of Otology and Skull Base Surgery, EYE & ENT Hospital of Fudan University; Shanghai Clinical Medical Center of Hearing Medicine; Key Laboratory of Hearing Medicine, Ministry of Health, Shanghai, China
| | - Zhen Gao
- Department of Otology and Skull Base Surgery, EYE & ENT Hospital of Fudan University; Shanghai Clinical Medical Center of Hearing Medicine; Key Laboratory of Hearing Medicine, Ministry of Health, Shanghai, China
| | - Dongdong Ren
- Department of Otology and Skull Base Surgery, EYE & ENT Hospital of Fudan University; Shanghai Clinical Medical Center of Hearing Medicine; Key Laboratory of Hearing Medicine, Ministry of Health, Shanghai, China
| | - Jing Wang
- Department of Otology and Skull Base Surgery, EYE & ENT Hospital of Fudan University; Shanghai Clinical Medical Center of Hearing Medicine; Key Laboratory of Hearing Medicine, Ministry of Health, Shanghai, China
| | - Fang-Lu Chi
- Department of Otology and Skull Base Surgery, EYE & ENT Hospital of Fudan University; Shanghai Clinical Medical Center of Hearing Medicine; Key Laboratory of Hearing Medicine, Ministry of Health, Shanghai, China
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Matsumoto H, Fujiwara S, Miyagi H, Nakamura N, Shiga Y, Ohta T, Tsuzuki M. Carbonic Anhydrase Inhibitors Induce Developmental Toxicity During Zebrafish Embryogenesis, Especially in the Inner Ear. MARINE BIOTECHNOLOGY (NEW YORK, N.Y.) 2017; 19:430-440. [PMID: 28695384 DOI: 10.1007/s10126-017-9763-7] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/11/2016] [Accepted: 06/06/2017] [Indexed: 06/07/2023]
Abstract
In vertebrates, carbonic anhydrases (CAs) play important roles in ion transport and pH regulation in many organs, including the eyes, kidneys, central nervous system, and inner ear. In aquatic organisms, the enzyme is inhibited by various chemicals present in the environment, such as heavy metals, pesticides, and pharmaceuticals. In this study, the effects of CA inhibitors, i.e., sulfonamides [ethoxyzolamide (EZA), acetazolamide (AZA), and dorzolamide (DZA)], on zebrafish embryogenesis were investigated. In embryos treated with the sulfonamides, abnormal development, such as smaller otoliths, an enlarged heart, an irregular pectoral fin, and aberrant swimming behavior, was observed. Especially, the development of otoliths and locomotor activity was severely affected by all the sulfonamides, and EZA was a consistently stronger inhibitor than AZA or DZA. In the embryos treated with EZA, inner ear hair cells containing several CA isoforms, which provide HCO3- to the endolymph for otolith calcification and maintain an appropriate pH there, were affected. Acridine orange/ethidium bromide staining indicated that the hair cell damage in the inner ear and pectral fin is due to apoptosis. Moreover, RNA measurement demonstrated that altered gene expression of cell cycle arrest- and apoptosis-related proteins p53, p21, p27, and Bcl-2 occurred even at 0.08 ppm with which normal development was observed. This finding suggests that a low concentration of EZA may affect embryogenesis via the apoptosis pathway. Thus, our findings demonstrated the importance of potential risk assessment of CA inhibition, especially regarding the formation of otoliths as a one of the most sensitive organs in embryogenesis.
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Affiliation(s)
- Hiroko Matsumoto
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Horinouchi, Hachioji, Tokyo, 192-0392, Japan
| | - Shoko Fujiwara
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Horinouchi, Hachioji, Tokyo, 192-0392, Japan.
| | - Hisako Miyagi
- Department of Life Science and Technology, Tokyo Institute of Technology, 4259-B13 Nagatsuta-cho, Midori-ku, Yokohama, 226-8501, Japan
| | - Nobuhiro Nakamura
- Department of Life Science and Technology, Tokyo Institute of Technology, 4259-B13 Nagatsuta-cho, Midori-ku, Yokohama, 226-8501, Japan
| | - Yasuhiro Shiga
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Horinouchi, Hachioji, Tokyo, 192-0392, Japan
| | - Toshihiro Ohta
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Horinouchi, Hachioji, Tokyo, 192-0392, Japan
| | - Mikio Tsuzuki
- School of Life Sciences, Tokyo University of Pharmacy and Life Sciences, Horinouchi, Hachioji, Tokyo, 192-0392, Japan
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Revuelta M, Santaolalla F, Arteaga O, Alvarez A, Sánchez-del-Rey A, Hilario E. Recent advances in cochlear hair cell regeneration-A promising opportunity for the treatment of age-related hearing loss. Ageing Res Rev 2017; 36:149-155. [PMID: 28414155 DOI: 10.1016/j.arr.2017.04.002] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/21/2017] [Revised: 04/05/2017] [Accepted: 04/10/2017] [Indexed: 01/22/2023]
Abstract
The objective of this paper is to review current information regarding the treatment of age-related hearing loss by using cochlear hair cell regeneration. Recent advances in the regeneration of the inner ear, including the usefulness of stem cells, are also presented. Based on the current literature, cochlear cell regeneration may well be possible in the short term and cochlear gene therapy may also be useful for the treatment of hearing loss associated with ageing. The present review provide further insight into the pathogenesis of Inner Ear senescence and aged-related hearing loss and facilitate the development of therapeutic strategies to repair hair cells damaged by ageing. More research will be needed in order to translate them into an effective treatment for deafness linked to cochlear senescence in humans.
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Żak M, van Oort T, Hendriksen FG, Garcia MI, Vassart G, Grolman W. LGR4 and LGR5 Regulate Hair Cell Differentiation in the Sensory Epithelium of the Developing Mouse Cochlea. Front Cell Neurosci 2016; 10:186. [PMID: 27559308 PMCID: PMC4988241 DOI: 10.3389/fncel.2016.00186] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/02/2016] [Accepted: 07/19/2016] [Indexed: 02/06/2023] Open
Abstract
In the developing cochlea, Wnt/β-catenin signaling positively regulates the proliferation of precursors and promotes the formation of hair cells by up-regulating Atoh1 expression. Not much, however, is known about the regulation of Wnt/β-catenin activity in the cochlea. In multiple tissues, the activity of Wnt/β-catenin signaling is modulated by an interaction between LGR receptors and their ligands from the R-spondin family. The deficiency in Lgr4 and Lgr5 genes leads to developmental malformations and lethality. Using the Lgr5 knock-in mouse line we show that loss of LGR5 function increases Wnt/β-catenin activity in the embryonic cochlea, resulting in a mild overproduction of inner and outer hair cells (OHC). Supernumerary hair cells are likely formed due to an up-regulation of the “pro-hair cell” transcription factors Atoh1, Nhlh1, and Pou4f3. Using a hypomorphic Lgr4 mouse model we showed a mild overproduction of OHCs in the heterozygous and homozygous Lgr4 mice. The loss of LGR4 function prolonged the proliferation in the mid-basal turn of E13 cochleae, causing an increase in the number of SOX2-positive precursor cells within the pro-sensory domain. The premature differentiation of hair cells progressed in a medial to lateral gradient in Lgr4 deficient embryos. No significant up-regulation of Atoh1 was observed following Lgr4 deletion. Altogether, our findings suggest that LGR4 and LGR5 play an important role in the regulation of hair cell differentiation in the embryonic cochlea.
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Affiliation(s)
- Magdalena Żak
- Department of Otorhinolaryngology and Head and Neck Surgery, Brain Center Rudolf Magnus, University Medical Center Utrecht Utrecht, Netherlands
| | - Thijs van Oort
- Department of Otorhinolaryngology and Head and Neck Surgery, Brain Center Rudolf Magnus, University Medical Center Utrecht Utrecht, Netherlands
| | - Ferry G Hendriksen
- Department of Otorhinolaryngology and Head and Neck Surgery, Brain Center Rudolf Magnus, University Medical Center Utrecht Utrecht, Netherlands
| | - Marie-Isabelle Garcia
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Faculty of Medicine, Université Libre de Bruxelles Brussels, Belgium
| | - Gilbert Vassart
- Institut de Recherche Interdisciplinaire en Biologie Humaine et Moléculaire, Faculty of Medicine, Université Libre de Bruxelles Brussels, Belgium
| | - Wilko Grolman
- Department of Otorhinolaryngology and Head and Neck Surgery, Brain Center Rudolf Magnus, University Medical Center Utrecht Utrecht, Netherlands
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Monroe JD, Rajadinakaran G, Smith ME. Sensory hair cell death and regeneration in fishes. Front Cell Neurosci 2015; 9:131. [PMID: 25954154 PMCID: PMC4404912 DOI: 10.3389/fncel.2015.00131] [Citation(s) in RCA: 54] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2015] [Accepted: 03/21/2015] [Indexed: 01/31/2023] Open
Abstract
Sensory hair cells are specialized mechanotransductive receptors required for hearing and vestibular function. Loss of hair cells in humans and other mammals is permanent and causes reduced hearing and balance. In the early 1980’s, it was shown that hair cells continue to be added to the inner ear sensory epithelia in cartilaginous and bony fishes. Soon thereafter, hair cell regeneration was documented in the chick cochlea following acoustic trauma. Since then, research using chick and other avian models has led to great insights into hair cell death and regeneration. However, with the rise of the zebrafish as a model organism for studying disease and developmental processes, there has been an increased interest in studying sensory hair cell death and regeneration in its lateral line and inner ears. Advances derived from studies in zebrafish and other fish species include understanding the effect of ototoxins on hair cells and finding otoprotectants to mitigate ototoxin damage, the role of cellular proliferation vs. direct transdifferentiation during hair cell regeneration, and elucidating cellular pathways involved in the regeneration process. This review will summarize research on hair cell death and regeneration using fish models, indicate the potential strengths and weaknesses of these models, and discuss several emerging areas of future studies.
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Affiliation(s)
- Jerry D Monroe
- Department of Biology, Western Kentucky University Bowling Green, KY, USA
| | - Gopinath Rajadinakaran
- Department of Genetics and Genome Sciences, University of Connecticut Health Center Farmington, CT, USA
| | - Michael E Smith
- Department of Biology, Western Kentucky University Bowling Green, KY, USA
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pRb phosphorylation regulates the proliferation of supporting cells in gentamicin-damaged neonatal avian utricle. Neuroreport 2015; 25:1144-50. [PMID: 25100553 DOI: 10.1097/wnr.0000000000000241] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
The ability of nonmammalian vertebrates to regenerate hair cells (HCs) after damage-induced HC loss has stimulated and inspired research in the field of HC regeneration. The protein pRb encoded by retinoblastoma gene Rb1 forces sensory progenitor cells to exit cell cycle and maintain differentiated HCs and supporting cells (SCs) in a quiescent state. pRb function is regulated by phosphorylation through the MEK/ERK or the pRb/Raf-1 signaling pathway. In our previous study, we have shown that pRb phosphorylation is crucial for progenitor cell proliferation and survival during the early embryonic stage of avian otocyst sensory epithelium development. However, in damaged avian utricle, the role of pRb in regulating the cell cycling of SCs or HCs regeneration still remains unclear. To further elucidate the function of pRb phosphorylation on SCs re-entering the cell cycle triggered by gentamycin-induced HCs damage, we isolated neonatal chicken utricles and treated them with the MEK inhibitor U0126 or the pRb/Raf-1 inhibitor RRD-251, respectively in vitro. We found that after gentamycin-induced HCs damage, pRb phosphorylation is important for the quiescent SCs re-entering the cell cycle in the neonatal chicken utricle. In addition, the proliferation of SCs decreased in a dose-dependent manner in response to both U0126 and RRD-251, which indicates that both the MEK/ERK and the pRb/Raf-1 signaling pathway play important roles in pRb phosphorylation in damaged neonatal chicken utricle. Together, these findings on the function of pRb in damaged neonatal chicken utricle improve our understanding of the regulation of the cell cycle of SCs after HCs loss and may shed light on the mammalian HC regeneration from SCs in damaged organs.
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Han Y, Hong L, Zhong C, Qiu J. Construction of recombinant adenoviral vector carrying <i>cyclinA2</i> gene. Drug Discov Ther 2015; 9:66-9. [DOI: 10.5582/ddt.2014.01048] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/10/2023]
Affiliation(s)
- Yu Han
- Department of Otolaryngology, Xijing Hospital, Fourth Military Medical University
| | - Liu Hong
- Xijing Hospital of Digestive Diseases, Fourth Military Medical University
| | - Cuiping Zhong
- Department of Otolaryngology, Xijing Hospital, Fourth Military Medical University
| | - Jianhua Qiu
- Department of Otolaryngology, Xijing Hospital, Fourth Military Medical University
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Regulation of p27Kip1 by Sox2 maintains quiescence of inner pillar cells in the murine auditory sensory epithelium. J Neurosci 2012; 32:10530-40. [PMID: 22855803 DOI: 10.1523/jneurosci.0686-12.2012] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022] Open
Abstract
Sox2 plays critical roles in cell fate specification during development and in stem cell formation; however, its role in postmitotic cells is largely unknown. Sox2 is highly expressed in supporting cells (SCs) of the postnatal mammalian auditory sensory epithelium, which unlike non-mammalian vertebrates remains quiescent even after sensory hair cell damage. Here, we induced the ablation of Sox2, specifically in SCs at three different postnatal ages (neonatal, juvenile and adult) in mice. In neonatal mice, Sox2-null inner pillar cells (IPCs, a subtype of SCs) proliferated and generated daughter cells, while other SC subtypes remained quiescent. Furthermore, p27(Kip1), a cell cycle inhibitor, was absent in Sox2-null IPCs. Similarly, upon direct deletion of p27(Kip1), p27(Kip1)-null IPCs also proliferated but retained Sox2 expression. Interestingly, cell cycle control of IPCs by Sox2-mediated expression of p27(Kip1) gradually declined with age. In addition, deletion of Sox2 or p27(Kip1) did not cause a cell fate change. Finally, chromatin immunoprecipitation with Sox2 antibodies and luciferase reporter assays with the p27(Kip1) promoter support that Sox2 directly activates p27(Kip1) transcription in postmitotic IPCs. Hence, in contrast to the well known activity of Sox2 in promoting proliferation and cell fate determination, our data demonstrate that Sox2 plays a novel role as a key upstream regulator of p27(Kip1) to maintain the quiescent state of postmitotic IPCs. Our studies suggest that manipulating Sox2 or p27(Kip1) expression is an effective approach to inducing proliferation of neonatal auditory IPCs, an initial but necessary step toward restoring hearing in mammals.
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Pan N, Kopecky B, Jahan I, Fritzsch B. Understanding the evolution and development of neurosensory transcription factors of the ear to enhance therapeutic translation. Cell Tissue Res 2012; 349:415-32. [PMID: 22688958 DOI: 10.1007/s00441-012-1454-0] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2012] [Accepted: 05/18/2012] [Indexed: 01/08/2023]
Abstract
Reconstructing a functional organ of Corti is the ultimate target towards curing hearing loss. Despite the impressive technical gains made over the last few years, many complications remain ahead for the two main restoration avenues: in vitro transformation of pluripotent cells into hair cell-like cells and adenovirus-mediated gene therapy. Most notably, both approaches require a more complete understanding of the molecular networks that ensure specific cell types form in the correct places to allow proper function of the restored organ of Corti. Important to this understanding are the basic helix-loop-helix (bHLH) transcription factors (TFs) that are highly diverse and serve to increase functional complexity but their evolutionary implementation in the inner ear neurosensory development is less conspicuous. To this end, we review the evolutionary and developmentally dynamic interactions of the three bHLH TFs that have been identified as the main players in neurosensory evolution and development, Neurog1, Neurod1 and Atoh1. These three TFs belong to the neurogenin/atonal family and evolved from a molecular precursor that likely regulated single sensory cell development in the ectoderm of metazoan ancestors but are now also expressed in other parts of the body, including the brain. They interact extensively via intracellular and intercellular cross-regulation to establish the two main neurosensory cell types of the ear, the hair cells and sensory neurons. Furthermore, the level and duration of their expression affect the specification of hair cell subtypes (inner hair cells vs. outer hair cells). We propose that appropriate manipulation of these TFs through their characterized binding sites may offer a solution by itself, or in conjunction with the two other approaches currently pursued by others, to restore the organ of Corti.
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Affiliation(s)
- Ning Pan
- Department of Biology, University of Iowa, College of Liberal Arts and Sciences, Iowa City, IA 52242, USA
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Roussel M. p27(Kip1) enforces maintenance of quiescence in the mammalian ear and the pituitary gland. Cell Cycle 2011; 10:2617-8. [PMID: 21836396 PMCID: PMC3233493 DOI: 10.4161/cc.10.16.16543] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
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Kopecky B, Fritzsch B. Regeneration of Hair Cells: Making Sense of All the Noise. Pharmaceuticals (Basel) 2011; 4:848-879. [PMID: 21966254 PMCID: PMC3180915 DOI: 10.3390/ph4060848] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2011] [Revised: 06/04/2011] [Accepted: 06/08/2011] [Indexed: 12/17/2022] Open
Abstract
Hearing loss affects hundreds of millions of people worldwide by dampening or cutting off their auditory connection to the world. Current treatments for sensorineural hearing loss (SNHL) with cochlear implants are not perfect, leaving regenerative medicine as the logical avenue to a perfect cure. Multiple routes to regeneration of damaged hair cells have been proposed and are actively pursued. Each route not only requires a keen understanding of the molecular basis of ear development but also faces the practical limitations of stem cell regulation in the delicate inner ear where topology of cell distribution is essential. Improvements in our molecular understanding of the minimal essential genes necessary for hair cell formation and recent advances in stem cell manipulation, such as seen with inducible pluripotent stem cells (iPSCs) and epidermal neural crest stem cells (EPI-NCSCs), have opened new possibilities to advance research in translational stem cell therapies for individuals with hearing loss. Despite this, more detailed network maps of gene expression are needed, including an appreciation for the roles of microRNAs (miRs), key regulators of transcriptional gene networks. To harness the true potential of stem cells for hair cell regeneration, basic science and clinical medicine must work together to expedite the transition from bench to bedside by elucidating the full mechanisms of inner ear hair cell development, including a focus on the role of miRs, and adapting this knowledge safely and efficiently to stem cell technologies.
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Affiliation(s)
- Benjamin Kopecky
- Department of Biology, University of Iowa, Iowa City, IA, 52242, USA
- Medical Scientist Training Program, Carver College of Medicine, University of Iowa, Iowa City, IA, 52242, USA
| | - Bernd Fritzsch
- Department of Biology, University of Iowa, Iowa City, IA, 52242, USA
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Staecker H, Praetorius M, Brough DE. Development of gene therapy for inner ear disease: Using bilateral vestibular hypofunction as a vehicle for translational research. Hear Res 2011; 276:44-51. [PMID: 21251965 DOI: 10.1016/j.heares.2011.01.006] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2010] [Revised: 01/10/2011] [Accepted: 01/11/2011] [Indexed: 12/16/2022]
Abstract
Despite the significant impact of hearing and balance disorders on the general population there are currently no dedicated pharmaceuticals that target the inner ear. Advances in molecular biology and neuroscience have improved our understanding of the inner ear allowing the development of a range of molecular targets that have the potential to treat both hearing and balance disorders. One of the principal advantages of the inner ear is that it is accessible through a variety of approaches that would allow a potential to be delivered locally rather than systemically. This significantly broadens the potential medications that can be developed and opens the possibility of local gene delivery as a therapeutic intervention. Several potential clinical targets have been identified including delivery of neurotrophin expressing genes as an adjunct to cochlear implantation, delivery of protective genes to prevent trauma and the development of strategies for regenerating inner ear sensory cells. In order to translate these potential therapeutics into humans we will want to optimize the gene delivery methodology, dosing and activity of the drug for therapeutic value. To this end we have developed a series of adenovectors that efficiently transduce the inner ear. The use of these gene delivery approaches are attractive for the potential of hair cell regeneration after loss induced by trauma or ototoxins. This approach is particularly suited for the development of molecular therapies targeted at the vestibular system given that no device based therapeutic such a cochlear implant available for vestibular loss.
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Affiliation(s)
- Hinrich Staecker
- Dept. Otolaryngology Head and Neck Surgery, University of Kansas School of Medicine, MS 3010, 3901 Rainbow Blvd, Kansas City, KS 66209, USA.
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Dong Y, Sui L, Yamaguchi F, Kamitori K, Hirata Y, Hossain MA, Suzuki A, Holley MC, Tokuda M. Phosphatase and tensin homolog deleted on chromosome 10 regulates sensory cell proliferation and differentiation of hair bundles in the mammalian cochlea. Neuroscience 2010; 170:1304-13. [PMID: 20727948 DOI: 10.1016/j.neuroscience.2010.08.024] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/08/2010] [Revised: 08/05/2010] [Accepted: 08/12/2010] [Indexed: 01/16/2023]
Abstract
Phosphatase and tensin homolog deleted on chromosome 10 (PTEN) is a tumor suppressor gene that regulates cell proliferation, differentiation and growth. It regulates neural and glioma stem/progenitor cell renewal and PTEN deletion can drive expansion of epithelial progenitors in the lung, enhancing their capacity for regeneration. Because it is expressed at relatively high levels in developing mammalian auditory hair cells we have analyzed the phenotype of the auditory epithelium in PTEN knock-out mice. PTEN(+/-) heterozygous littermates have only one functional copy of the gene and show clear evidence for haploinsufficiency in the organ of Corti. Auditory sensory epithelial progenitors withdraw from the cell cycle later than in wild-type animals and this is associated with increases in the numbers of both inner and outer hair cells. The cytoskeletal differentiation of hair cells was also affected. While many hair bundles on the hair cells appeared to develop normally, others were structurally disorganized and a number were missing, apparently lost after they had been formed. The results show that PTEN plays a novel role in regulating cell proliferation and differentiation of hair bundles in auditory sensory epithelial cells and suggest that PTEN signaling pathways may provide therapeutic targets for auditory sensory regeneration.
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Affiliation(s)
- Y Dong
- Department of Cell Physiology, Faculty of Medicine, Kagawa University, 1750-1 Ikenobe, Miki-cho, Kita-gun, Kagawa 761-0793, Japan.
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Zhong C, Han Y, Qiu J, Lu L, Chen Y, Chen J, Hei R, Mi W. A comparison of the proliferative capacity and ultrastructure of proliferative cells from the cochleae of newborn rats of different ages. Int J Pediatr Otorhinolaryngol 2010; 74:192-7. [PMID: 19963281 DOI: 10.1016/j.ijporl.2009.11.009] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/18/2009] [Revised: 11/07/2009] [Accepted: 11/09/2009] [Indexed: 12/29/2022]
Abstract
OBJECTIVE Recent reports have shown that multipotent stem cells/progenitor cells that are capable of proliferation and regeneration are present in mammalian cochleae. However, progenitor cells have not been isolated from the adult cochlea. We examined the proliferative potential of cells derived from neonatal rats of various ages. The determination of the differences between the proliferative cells from rats of different ages may provide clues to the mechanisms controlling the destiny of these cells. METHODS Proliferative cells were isolated from the cochleae of 1-, 7-, and 14-day-old rats, and the proliferative capacity and ultrastructure of the cells from each age group were assessed using flow cytometry and transmission electron microscopy, respectively. RESULTS During the first two postnatal weeks, the number of proliferative cells gradually fell to zero. This decrease occurred in parallel with the impairment of the proliferative capacity of the cells and the accumulation of proliferative cells in G0/G1. In addition, some of the cells exited the cell cycle by means of gradual maturity and apoptosis. CONCLUSIONS Our study suggests that cochlear proliferative cells are remnants of the progenitor cells that originally gave rise to the sensory epithelium. The disappearance of the cochlear proliferative cells in adult mammalian cochleae may result from their differentiation and/or apoptosis.
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Affiliation(s)
- Cuiping Zhong
- Department of Otolaryngology, Xijing Hospital, Fourth Military Medical University, Changlexilu 15, Xi'an 710032, Shanxi Province, China
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Han Y, Zhong C, Hong L, Wang Y, Qiao L, Qiu J. Effect of c-myc on the ultrastructural structure of cochleae in guinea pigs with noise induced hearing loss. Biochem Biophys Res Commun 2009; 390:458-62. [PMID: 19785991 DOI: 10.1016/j.bbrc.2009.09.091] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2009] [Accepted: 09/23/2009] [Indexed: 11/16/2022]
Abstract
Noise over-stimulation may induce hair cells loss and hearing deficit. The c-myc oncogene is a major regulator for cell proliferation, growth, and apoptosis. However, the role of this gene in the mammalian cochlea is still unclear. The study was designed to firstly investigate its function under noise condition, from the aspect of cochlear ultrastructural changes. We had established the adenoviral vector of c-myc gene and delivered the adenovirus suspension into the scala tympani of guinea pigs 4 days before noise exposure. The empty adenoviral vectors were injected as control. Then, all subjects were exposed to 4-kHz octave-band noise at 110dB SPL for 8h/day, 3 days consecutively. Auditory thresholds were assessed by auditory brainstem response, prior to and 7 days following noise exposure. On the seventh days after noise exposure, the cochlear sensory epithelia surface was observed microscopically and the cochleae were taken to study the ultrastructural changes. The results indicated that auditory threshold shift after noise exposure was higher in the ears treated with Ad.EGFP than that treated with Ad.c-myc-EGFP. Stereocilia loss and the disarrangement of outer hair cells were observed, with greater changes found in the Ad.EGFP group. Also, the ultrastructure changes were severe in the Ad.EGFP group, but not obvious in the Ad.c-myc-EGFP group. Therefore, c-myc gene might play an unexpected role in hearing functional and morphological protection from acoustic trauma.
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Affiliation(s)
- Yu Han
- Department of Otolaryngology, Xijing Hospital, Fourth Military Medical University, Xi'an, 710032 Shaanxi Province, China
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Kelly MC, Chen P. Development of form and function in the mammalian cochlea. Curr Opin Neurobiol 2009; 19:395-401. [PMID: 19683914 DOI: 10.1016/j.conb.2009.07.010] [Citation(s) in RCA: 71] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2009] [Revised: 07/06/2009] [Accepted: 07/13/2009] [Indexed: 01/05/2023]
Abstract
The cochlea possesses specialized features to receive sound signals and to resolve and convert the frequency and intensity components within each signal for auditory perception. It consists of precisely patterned and polarized sensory cells adorned with a highly specialized mechanotransduction apparatus for sensitivity and adaptation, and discrete nonsensory cellular networks for biochemical and mechanical support to drive an integrated cellular response and mechanotransduction. This review summarizes recent discoveries about the roles of FGF, Notch, and Hedgehog signaling and transcriptional factors in the differentiation and patterning of the auditory sensory organ, the Usher complex, and the planar cell polarity pathway in the formation and polarization of mechanotransduction component hair bundles, and the contribution of nonsensory cell networks in the stria vascularis and the sensory region toward the maturation of the mammalian cochlea.
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Affiliation(s)
- Michael C Kelly
- Department of Cell Biology, Emory University, 615 Michael Street, Atlanta, GA 30322, USA
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Chen J, Wang F, Gao X, Zha D, Xue T, Cheng X, Zhong C, Han Y, Qiu J. Decreased level of cyclin A2 in rat cochlea development and cochlear stem cell differentiation. Neurosci Lett 2009; 453:166-9. [DOI: 10.1016/j.neulet.2009.02.019] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2008] [Revised: 02/09/2009] [Accepted: 02/09/2009] [Indexed: 11/27/2022]
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