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Abstract
It is well established that humans and other mammals are minimally regenerative compared with organisms such as zebrafish, salamander or amphibians. In recent years, however, the identification of regenerative potential in neonatal mouse tissues that normally heal poorly in adults has transformed our understanding of regenerative capacity in mammals. In this Review, we survey the mammalian tissues for which regenerative or improved neonatal healing has been established, including the heart, cochlear hair cells, the brain and spinal cord, and dense connective tissues. We also highlight common and/or tissue-specific mechanisms of neonatal regeneration, which involve cells, signaling pathways, extracellular matrix, immune cells and other factors. The identification of such common features across neonatal tissues may direct therapeutic strategies that will be broadly applicable to multiple adult tissues.
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Affiliation(s)
| | - Alice H. Huang
- Department of Orthopedic Surgery, Columbia University, New York, NY 10032, USA
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2
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Abstract
Biologic therapies have the ability to fundamentally change the management of hearing loss; clinicians need to familiarize themselves with their prospective applications in practice. This article reviews the current application of 4 categories of biological therapeutics-growth factors, apoptosis inhibitors, monoclonal antibodies, and gene therapy-in otology and their potential future directions and applications.
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Affiliation(s)
- Steven A Gordon
- Otolaryngology-Head & Neck Surgery, University of Utah Health, 50 North Medical Drive 3C120 SOM, Salt Lake City, UT 84132, USA
| | - Richard K Gurgel
- Otolaryngology-Head & Neck Surgery, University of Utah Health, 50 North Medical Drive 3C120 SOM, Salt Lake City, UT 84132, USA.
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3
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Ding N, Lee S, Lieber-Kotz M, Yang J, Gao X. Advances in genome editing for genetic hearing loss. Adv Drug Deliv Rev 2021; 168:118-133. [PMID: 32387678 DOI: 10.1016/j.addr.2020.05.001] [Citation(s) in RCA: 20] [Impact Index Per Article: 6.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/23/2019] [Revised: 04/27/2020] [Accepted: 05/04/2020] [Indexed: 02/07/2023]
Abstract
According to the World Health Organization, hearing loss affects over 466 million people worldwide and is the most common human sensory impairment. It is estimated that genetic factors contribute to the causation of approximately 50% of congenital hearing loss. Yet, curative approaches to reversing or preventing genetic hearing impairment are still limited. The clustered regularly interspaced short palindromic repeats-associated protein 9 (CRISPR-Cas9) systems enable programmable and targeted gene editing in highly versatile manners and offer new gene therapy strategies for genetic hearing loss. Here, we summarize the most common deafness-associated genes, illustrate recent strategies undertaken by using CRISPR-Cas9 systems for targeted gene editing and further compare the CRISPR strategies to non-CRISPR gene therapies. We also examine the merits of different vehicles and delivery forms of genome editing agents. Lastly, we describe the development of animal models that could facilitate the eventual clinical applications of the CRISPR technology to the treatment of genetic hearing diseases.
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Developmental and Functional Hair Cell-Like Cells Induced by Atoh1 Overexpression in the Adult Mammalian Cochlea In Vitro. Neural Plast 2020; 2020:8885813. [PMID: 33204251 PMCID: PMC7661126 DOI: 10.1155/2020/8885813] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/24/2020] [Revised: 09/17/2020] [Accepted: 10/21/2020] [Indexed: 12/22/2022] Open
Abstract
Hair cells (HCs) in the mammalian cochleae cannot spontaneously regenerate once damaged, resulting in permanent hearing loss. It has been shown that Atoh1 overexpression induces hair cell-like cells (HCLCs) in the cochlea of newborn rodents, but this is hard to achieve in adult mammals. In this study, we used a three-dimensional cochlear culture system and an adenoviral-mediated delivery vector to overexpress Atoh1 in adult mouse cochleae. HCLCs were successfully induced from 3 days after virus infection (3 DVI) in vitro, and the number increased with time. HCLCs were myosin7a positive and distinguishable from remnant HCs in a culture environment. Meanwhile, patch-clamp results showed that noninactive outward potassium currents (sustained outward potassium currents) could be recorded in HCLCs and that their magnitude increased with time, similar to normal HCs. Furthermore, transient HCN currents were recorded in some HCLCs, indicating that the HCLCs experienced a developmental stage similar to normal HCs. We also compared the electrophysiological features of HCLCs from adult mice with native HCs and found the HCLCs gradually matured, similar to the normal HCs. Meanwhile, HCLCs from adult mice possessed the same bundles as developmental HCs. However, these HCLCs did not express prestin, which is a special marker for outer hair cells (OHCs), even at 13 DVI. These results demonstrate that Atoh1 overexpression induces HCLC formation in the adult mammalian cochlea and that these HCLCs were functional and experienced a developmental process similar to that of normal HCs.
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Inner Ear Gene Therapies Take Off: Current Promises and Future Challenges. J Clin Med 2020; 9:jcm9072309. [PMID: 32708116 PMCID: PMC7408650 DOI: 10.3390/jcm9072309] [Citation(s) in RCA: 66] [Impact Index Per Article: 16.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2020] [Revised: 07/13/2020] [Accepted: 07/15/2020] [Indexed: 11/16/2022] Open
Abstract
Hearing impairment is the most frequent sensory deficit in humans of all age groups, from children (1/500) to the elderly (more than 50% of the over-75 s). Over 50% of congenital deafness are hereditary in nature. The other major causes of deafness, which also may have genetic predisposition, are aging, acoustic trauma, ototoxic drugs such as aminoglycosides, and noise exposure. Over the last two decades, the study of inherited deafness forms and related animal models has been instrumental in deciphering the molecular, cellular, and physiological mechanisms of disease. However, there is still no curative treatment for sensorineural deafness. Hearing loss is currently palliated by rehabilitation methods: conventional hearing aids, and for more severe forms, cochlear implants. Efforts are continuing to improve these devices to help users to understand speech in noisy environments and to appreciate music. However, neither approach can mediate a full recovery of hearing sensitivity and/or restoration of the native inner ear sensory epithelia. New therapeutic approaches based on gene transfer and gene editing tools are being developed in animal models. In this review, we focus on the successful restoration of auditory and vestibular functions in certain inner ear conditions, paving the way for future clinical applications.
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Menendez L, Trecek T, Gopalakrishnan S, Tao L, Markowitz AL, Yu HV, Wang X, Llamas J, Huang C, Lee J, Kalluri R, Ichida J, Segil N. Generation of inner ear hair cells by direct lineage conversion of primary somatic cells. eLife 2020; 9:e55249. [PMID: 32602462 PMCID: PMC7326493 DOI: 10.7554/elife.55249] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Accepted: 05/27/2020] [Indexed: 02/06/2023] Open
Abstract
The mechanoreceptive sensory hair cells in the inner ear are selectively vulnerable to numerous genetic and environmental insults. In mammals, hair cells lack regenerative capacity, and their death leads to permanent hearing loss and vestibular dysfunction. Their paucity and inaccessibility has limited the search for otoprotective and regenerative strategies. Growing hair cells in vitro would provide a route to overcome this experimental bottleneck. We report a combination of four transcription factors (Six1, Atoh1, Pou4f3, and Gfi1) that can convert mouse embryonic fibroblasts, adult tail-tip fibroblasts and postnatal supporting cells into induced hair cell-like cells (iHCs). iHCs exhibit hair cell-like morphology, transcriptomic and epigenetic profiles, electrophysiological properties, mechanosensory channel expression, and vulnerability to ototoxin in a high-content phenotypic screening system. Thus, direct reprogramming provides a platform to identify causes and treatments for hair cell loss, and may help identify future gene therapy approaches for restoring hearing.
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Affiliation(s)
- Louise Menendez
- Department of Stem Cell and Regenerative Medicine, University of Southern CaliforniaLos AngelesUnited States
- Eli and Edythe Broad Center, University of Southern CaliforniaLos AngelesUnited States
- Zilkha Neurogenetic Institute, University of Southern CaliforniaLos AngelesUnited States
| | - Talon Trecek
- Department of Stem Cell and Regenerative Medicine, University of Southern CaliforniaLos AngelesUnited States
- Eli and Edythe Broad Center, University of Southern CaliforniaLos AngelesUnited States
| | - Suhasni Gopalakrishnan
- Department of Stem Cell and Regenerative Medicine, University of Southern CaliforniaLos AngelesUnited States
- Eli and Edythe Broad Center, University of Southern CaliforniaLos AngelesUnited States
- Zilkha Neurogenetic Institute, University of Southern CaliforniaLos AngelesUnited States
| | - Litao Tao
- Department of Stem Cell and Regenerative Medicine, University of Southern CaliforniaLos AngelesUnited States
- Eli and Edythe Broad Center, University of Southern CaliforniaLos AngelesUnited States
| | - Alexander L Markowitz
- Zilkha Neurogenetic Institute, University of Southern CaliforniaLos AngelesUnited States
- USC Caruso Department of Otolaryngology – Head and Neck Surgery, University of Southern CaliforniaLos AngelesUnited States
| | - Haoze V Yu
- Department of Stem Cell and Regenerative Medicine, University of Southern CaliforniaLos AngelesUnited States
- Eli and Edythe Broad Center, University of Southern CaliforniaLos AngelesUnited States
| | - Xizi Wang
- Department of Stem Cell and Regenerative Medicine, University of Southern CaliforniaLos AngelesUnited States
- Eli and Edythe Broad Center, University of Southern CaliforniaLos AngelesUnited States
| | - Juan Llamas
- Department of Stem Cell and Regenerative Medicine, University of Southern CaliforniaLos AngelesUnited States
- Eli and Edythe Broad Center, University of Southern CaliforniaLos AngelesUnited States
| | | | - James Lee
- DRVision TechnologiesBellevueUnited States
| | - Radha Kalluri
- Zilkha Neurogenetic Institute, University of Southern CaliforniaLos AngelesUnited States
- USC Caruso Department of Otolaryngology – Head and Neck Surgery, University of Southern CaliforniaLos AngelesUnited States
| | - Justin Ichida
- Department of Stem Cell and Regenerative Medicine, University of Southern CaliforniaLos AngelesUnited States
- Eli and Edythe Broad Center, University of Southern CaliforniaLos AngelesUnited States
- Zilkha Neurogenetic Institute, University of Southern CaliforniaLos AngelesUnited States
| | - Neil Segil
- Department of Stem Cell and Regenerative Medicine, University of Southern CaliforniaLos AngelesUnited States
- Eli and Edythe Broad Center, University of Southern CaliforniaLos AngelesUnited States
- USC Caruso Department of Otolaryngology – Head and Neck Surgery, University of Southern CaliforniaLos AngelesUnited States
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7
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Géléoc GGS, El-Amraoui A. Disease mechanisms and gene therapy for Usher syndrome. Hear Res 2020; 394:107932. [PMID: 32199721 DOI: 10.1016/j.heares.2020.107932] [Citation(s) in RCA: 48] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/15/2019] [Revised: 02/03/2020] [Accepted: 02/26/2020] [Indexed: 12/11/2022]
Abstract
Usher syndrome (USH) is a major cause of deaf-blindness in humans, affecting ∼400 000 patients worldwide. Three clinical subtypes, USH1-3, have been defined, with 10 USH genes identified so far. In recent years, in addition to identification of new Usher genes and diagnostic tools, major progress has been made in understanding the role of Usher proteins and how they cooperate through interaction networks to ensure proper development, architecture and function of the stereociliary bundle at the apex of sensory hair cells in the inner ear. Several Usher mouse models of known human Usher genes have been characterized. These mice faithfully reproduce the auditory phenotype associated with Usher syndrome and the vestibular phenotype associated with some mutations in USH genes, particularly USH1. Interestingly, very few mouse models of Usher syndrome recapitulate the retinal phenotype associated with the disease in human. Usher patients can benefit from hearing aids or cochlear implants, which partially alleviate auditory sensory deprivation. However, there are currently no biological treatments available for auditory or visual dysfunction in Usher patients. Development of novel therapies for Usher syndrome has sprouted over the past decade, building on recent progress in gene transfer and new gene editing tools. Promising success demonstrating recovery of hearing and balance functions have been obtained via distinct therapeutic strategies in animal models. Clinical translation to Usher patients, however, calls for further improvements and concerted efforts to overcome the challenges ahead.
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Affiliation(s)
- Gwenaelle G S Géléoc
- Boston Children's Hospital and Harvard Medical School, 3, Blackfan circle, Center for Life Science, 03001, Boston, MA, 02115, United States.
| | - Aziz El-Amraoui
- Unit Progressive Sensory Disorders, Institut Pasteur, INSERM-UMRS1120, Sorbonne Université, 25 rue du Dr. Roux, 75015, Paris, France.
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8
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Zheng Y, Luo W, Ma R, Cong N, Ren D, Chi F, Yang J. The Atoh1 expression levels are correlated with the arrangement, ciliary morphology, and electrophysiological characteristics of ectopic hair cell-like cells. Neurosci Lett 2020; 720:134758. [PMID: 31945449 DOI: 10.1016/j.neulet.2020.134758] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2019] [Revised: 12/15/2019] [Accepted: 01/13/2020] [Indexed: 10/25/2022]
Abstract
Previous reports have suggested that the level and duration of Atoh1 expression are correlated with the survival, arrangement and stereociliary bundle-related morphology of hair cells during development, but whether Atoh1 expression levels are correlated with the arrangement, bundle formation and electrophysiological characteristics of newly formed hair cells is unknown. To address this question, cultured cochlear explants obtained from neonatal rats were treated with different titers of a human adenovirus serotype 5 (Ad5) vector encoding Atoh1 and/or EGFP (EGFP-Atoh1+/-). The results showed that higher EGFP-Atoh1 concentrations led to higher initial Atoh1 mRNA expression levels and induced greater numbers of ectopic hair cell-like cells (EHCLCs) in the lesser epithelial ridge (LER). Furthermore, gradual increases in the number of EHCLCs were associated with the progressive conversion of the LER region similarly to that of hair cells during development. Some of the cilia on EHCLCs with higher Atoh1 expression were regularly arranged in a manner similar to that of normal hair bundles. As demonstrated through patch clamp recordings, high Atoh1 expression was associated with significantly decreased proportions of cells with Ih currents, significantly reduced proportions of transient potassium channel currents, and potassium channel currents with a greatly increased mean amplitude, which indicated that EHCLCs with high Atoh1 expression were more mature than those with low Atoh1 expression. Overall, the evidence suggests that the Atoh1 expression levels affect not only the arrangement and ciliary morphology of hair cells but also the electrophysiological characteristics of Atoh1-induced EHCLCs, and these findings provide important guidance for future therapies aimed at treating deafness.
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Affiliation(s)
- Yu Zheng
- Department of Otology and Skull Base Surgery, Eye Ear Nose and Throat Hospital, Fudan University, Shanghai 200031, China; Shanghai Clinical Medical Center of Hearing Medicine, Shanghai 200031, China; Key Laboratory of Hearing Medicine of National Health Commission of the People's Republic of China, Shanghai 20031, China; Research Institute of Otolaryngology, Fudan University, Shanghai 200031, China
| | - Wenwei Luo
- Department of Otology and Skull Base Surgery, Eye Ear Nose and Throat Hospital, Fudan University, Shanghai 200031, China; Shanghai Clinical Medical Center of Hearing Medicine, Shanghai 200031, China; Key Laboratory of Hearing Medicine of National Health Commission of the People's Republic of China, Shanghai 20031, China; Research Institute of Otolaryngology, Fudan University, Shanghai 200031, China
| | - Rui Ma
- Key Laboratory of Hearing Medicine of National Health Commission of the People's Republic of China, Shanghai 20031, China; Research Institute of Otolaryngology, Fudan University, Shanghai 200031, China
| | - Ning Cong
- Key Laboratory of Hearing Medicine of National Health Commission of the People's Republic of China, Shanghai 20031, China; Research Institute of Otolaryngology, Fudan University, Shanghai 200031, China
| | - Dongdong Ren
- Department of Otology and Skull Base Surgery, Eye Ear Nose and Throat Hospital, Fudan University, Shanghai 200031, China; Shanghai Clinical Medical Center of Hearing Medicine, Shanghai 200031, China; Key Laboratory of Hearing Medicine of National Health Commission of the People's Republic of China, Shanghai 20031, China; Research Institute of Otolaryngology, Fudan University, Shanghai 200031, China.
| | - Fanglu Chi
- Department of Otology and Skull Base Surgery, Eye Ear Nose and Throat Hospital, Fudan University, Shanghai 200031, China; Shanghai Clinical Medical Center of Hearing Medicine, Shanghai 200031, China; Key Laboratory of Hearing Medicine of National Health Commission of the People's Republic of China, Shanghai 20031, China; Research Institute of Otolaryngology, Fudan University, Shanghai 200031, China.
| | - Juanmei Yang
- Department of Otology and Skull Base Surgery, Eye Ear Nose and Throat Hospital, Fudan University, Shanghai 200031, China; Shanghai Clinical Medical Center of Hearing Medicine, Shanghai 200031, China; Key Laboratory of Hearing Medicine of National Health Commission of the People's Republic of China, Shanghai 20031, China; Research Institute of Otolaryngology, Fudan University, Shanghai 200031, China.
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9
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Ma Y, Wise AK, Shepherd RK, Richardson RT. New molecular therapies for the treatment of hearing loss. Pharmacol Ther 2019; 200:190-209. [PMID: 31075354 DOI: 10.1016/j.pharmthera.2019.05.003] [Citation(s) in RCA: 45] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2019] [Accepted: 05/02/2019] [Indexed: 12/11/2022]
Abstract
An estimated 466 million people suffer from hearing loss worldwide. Sensorineural hearing loss is characterized by degeneration of key structures of the sensory pathway in the cochlea such as the sensory hair cells, the primary auditory neurons and their synaptic connection to the hair cells - the ribbon synapse. Various strategies to protect or regenerate these sensory cells and structures are the subject of intensive research. Yet despite recent advances in our understandings of the capacity of the cochlea for repair and regeneration there are currently no pharmacological or biological interventions for hearing loss. Current research focusses on localized cochlear drug, gene and cell-based therapies. One of the more promising drug-based therapies is based on neurotrophic factors for the repair of the ribbon synapse after noise exposure, as well as preventing loss of primary auditory neurons and regrowth of the auditory neuron fibers after severe hearing loss. Drug therapy delivery technologies are being employed to address the specific needs of neurotrophin and other therapies for hearing loss that include the need for high doses, long-term delivery, localised or cell-specific targeting and techniques for their safe and efficacious delivery to the cochlea. Novel biomaterials are enabling high payloads of drugs to be administered to the cochlea with subsequent slow-release properties that are proving to be beneficial for treating hearing loss. In parallel, new gene therapy technologies are addressing the need for cell specificity and high efficacy for the treatment of both genetic and acquired hearing loss with promising reports of hearing recovery. Some biomaterials and cell therapies are being used in conjunction with the cochlear implant ensuring therapeutic benefit to the primary neurons during electrical stimulation. This review will introduce the auditory system, hearing loss and the potential for repair and regeneration in the cochlea. Drug delivery to the cochlea will then be reviewed, with a focus on new biomaterials, gene therapy technologies, cell therapy and the use of the cochlear implant as a vehicle for drug delivery. With the current pre-clinical research effort into therapies for hearing loss, including clinical trials for gene therapy, the future for the treatment for hearing loss is looking bright.
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Affiliation(s)
- Yutian Ma
- Bionics Institute, East Melbourne, Australia; ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, Australia; University of Melbourne, Department of Chemical Engineering, Parkville, Victoria, Australia
| | - Andrew K Wise
- Bionics Institute, East Melbourne, Australia; University of Melbourne, Medical Bionics Department, East Melbourne, Australia; University of Melbourne, Department of Surgery - Otolaryngology, East Melbourne, Australia
| | - Robert K Shepherd
- Bionics Institute, East Melbourne, Australia; University of Melbourne, Medical Bionics Department, East Melbourne, Australia; University of Melbourne, Department of Surgery - Otolaryngology, East Melbourne, Australia
| | - Rachael T Richardson
- Bionics Institute, East Melbourne, Australia; University of Melbourne, Medical Bionics Department, East Melbourne, Australia; University of Melbourne, Department of Surgery - Otolaryngology, East Melbourne, Australia.
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10
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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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11
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Ahmed H, Shubina-Oleinik O, Holt JR. Emerging Gene Therapies for Genetic Hearing Loss. J Assoc Res Otolaryngol 2017; 18:649-670. [PMID: 28815315 PMCID: PMC5612923 DOI: 10.1007/s10162-017-0634-8] [Citation(s) in RCA: 78] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2017] [Accepted: 07/04/2017] [Indexed: 12/31/2022] Open
Abstract
Gene therapy, or the treatment of human disease using genetic material, for inner ear dysfunction is coming of age. Recent progress in developing gene therapy treatments for genetic hearing loss has demonstrated tantalizing proof-of-principle in animal models. While successful translation of this progress into treatments for humans awaits, there is growing interest from patients, scientists, clinicians, and industry. Nonetheless, it is clear that a number of hurdles remain, and expectations for total restoration of auditory function should remain tempered until these challenges have been overcome. Here, we review progress, prospects, and challenges for gene therapy in the inner ear. We focus on technical aspects, including routes of gene delivery to the inner ear, choice of vectors, promoters, inner ear targets, therapeutic strategies, preliminary success stories, and points to consider for translating of these successes to the clinic.
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Affiliation(s)
- Hena Ahmed
- Departments of Otolaryngology and Neurology, F.M. Kirby Neurobiology Center Boston Children's Hospital and Harvard Medical School, Boston, MA, USA
| | - Olga Shubina-Oleinik
- Departments of Otolaryngology and Neurology, F.M. Kirby Neurobiology Center Boston Children's Hospital and Harvard Medical School, Boston, MA, USA
| | - Jeffrey R Holt
- Departments of Otolaryngology and Neurology, F.M. Kirby Neurobiology Center Boston Children's Hospital and Harvard Medical School, Boston, MA, USA.
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12
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Afferent synaptogenesis between ectopic hair-cell-like cells and neurites of spiral ganglion induced by Atoh1 in mammals in vitro. Neuroscience 2017; 357:185-196. [PMID: 28576729 DOI: 10.1016/j.neuroscience.2017.05.040] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2016] [Revised: 05/20/2017] [Accepted: 05/23/2017] [Indexed: 11/20/2022]
Abstract
Newly formed ectopic hair-cell-like cells (EHCLCs) induced by overexpression of atonal homolog 1 (Atoh1) in vitro were found to possess features of endogenous hair cells (HCs) in previous reports and in the present study. However, limited information is available regarding whether EHCLCs and native spiral ganglion neurons (SGNs) form afferent synapses, which are important for the restoration of hearing. In the current study, we focused on the afferent synaptogenesis between EHCLCs and SGN-derived dendrites. Cochlear explants of auditory epithelia with native SGNs retained were cultured in vitro, and human adenovirus serotype 5 (Ad5) vectors encoding Atoh1 were used to overexpress Atoh1 and induce EHCLCs. We observed that the neurites of the original SGNs extended toward the lesser epithelial ridge (LER) and innervated the EHCLCs. Immunohistochemical analyses revealed the expression of presynaptic ribbon C-terminal-binding protein 2 (CtBP2) and postsynaptic density protein (PSD)-95 in the nerve endings of SGN-derived neurons adjacent to EHCLCs. PSD-95 was located directly opposite CtBP2-positive puncta in the terminals of branches of SGNs, demonstrating that the neurites of SGNs formed afferent-like synaptic connections with EHCLCs. However, the expression of glutamate receptor type 2 (GluR2) could not be detected in the terminals of branches of SGNs surrounding EHCLCs. In addition, we found that the presynaptic ribbon (CtBP2) formation in EHCLCs preceded neural innervation. Furthermore, CtBP2-positive puncta increased and then decreased in EHCLCs, similar to the changes observed in endogenous HCs in terms of their number and distribution. Our finding of the generation of cochlear afferent synapses between EHCLCs and original SGNs will lay the foundation for regenerative approaches to restoring hearing after hair cell loss.
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13
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In Vivo Interplay between p27 Kip1, GATA3, ATOH1, and POU4F3 Converts Non-sensory Cells to Hair Cells in Adult Mice. Cell Rep 2017; 19:307-320. [PMID: 28402854 DOI: 10.1016/j.celrep.2017.03.044] [Citation(s) in RCA: 96] [Impact Index Per Article: 13.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2016] [Revised: 11/28/2016] [Accepted: 03/14/2017] [Indexed: 12/11/2022] Open
Abstract
Hearing loss is widespread and persistent because mature mammalian auditory hair cells (HCs) are nonregenerative. In mice, the ability to regenerate HCs from surrounding supporting cells (SCs) declines abruptly after postnatal maturation. We find that combining p27Kip1 deletion with ectopic ATOH1 expression surmounts this age-related decline, leading to conversion of SCs to HCs in mature mouse cochleae and after noise damage. p27Kip1 deletion, independent of canonical effects on Rb-family proteins, upregulated GATA3, a co-factor for ATOH1 that is lost from SCs with age. Co-activation of GATA3 or POU4F3 and ATOH1 promoted conversion of SCs to HCs in adult mice. Activation of POU4F3 alone also converted mature SCs to HCs in vivo. These data illuminate a genetic pathway that initiates auditory HC regeneration and suggest p27Kip1, GATA3, and POU4F3 as additional therapeutic targets for ATOH1-mediated HC regeneration.
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14
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Yang X, Qian X, Ma R, Wang X, Yang J, Luo W, Chen P, Chi F, Ren D. Establishment of planar cell polarity is coupled to regional cell cycle exit and cell differentiation in the mouse utricle. Sci Rep 2017; 7:43021. [PMID: 28230212 PMCID: PMC5322371 DOI: 10.1038/srep43021] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Accepted: 01/18/2017] [Indexed: 01/16/2023] Open
Abstract
Sensory hair cells are coordinately oriented within each inner ear sensory organ to exhibit a particular form of planar cell polarity (PCP) necessary for mechanotransduction. However, the developmental events associated with establishing PCP in the vestibule are unclear, hindering data interpretation and employment of the vestibule for PCP studies. Herein, we investigated PCP of the mouse vestibular organs. We further characterised cell cycle exit, cell differentiation, and PCP establishment in the utricle. We found that hair cells formed first in the striolar and medial extrastriolar (MES) regions of the utricle at embryonic day 11.5 (E11.5), while cells in the lateral extrastriolar region (LES) mostly formed at E13.5. Cell differentiation was initiated in the striolar region, which expanded first toward the MES, then to the LES by E15.5. The polarity of hair cells was established at birth along a putative line of polarity reversal (LPR), lateral to the striolar region. Core PCP protein Vangl2 emerged in the cell boundaries since E11.5, while cell intrinsic polarity protein Gαi3 appeared at E12.5, then polarized to the bare zone of individual hair cell at E13.5. These findings provide a blueprint of the developmental events associated with establishing PCP in the utricle.
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Affiliation(s)
- Xiaoyu Yang
- Department of Otology and Skull Base Surgery, Eye &ENT Hospital of Fudan University, Shanghai 200031, China.,Shanghai Clinical Medical Center of Hearing Medicine, Eye &ENT Hospital of Fudan University, Shanghai 200031, China
| | - Xiaoqing Qian
- Department of Otology and Skull Base Surgery, Eye &ENT Hospital of Fudan University, Shanghai 200031, China.,Shanghai Clinical Medical Center of Hearing Medicine, Eye &ENT Hospital of Fudan University, Shanghai 200031, China
| | - Rui Ma
- Department of Otology and Skull Base Surgery, Eye &ENT Hospital of Fudan University, Shanghai 200031, China.,Shanghai Clinical Medical Center of Hearing Medicine, Eye &ENT Hospital of Fudan University, Shanghai 200031, China.,Department of Research Center, Eye &ENT Hospital of Fudan University, Shanghai 200031, China
| | - Xinwei Wang
- Department of Otology and Skull Base Surgery, Eye &ENT Hospital of Fudan University, Shanghai 200031, China.,Shanghai Clinical Medical Center of Hearing Medicine, Eye &ENT Hospital of Fudan University, Shanghai 200031, China
| | - Juanmei Yang
- Department of Otology and Skull Base Surgery, Eye &ENT Hospital of Fudan University, Shanghai 200031, China.,Shanghai Clinical Medical Center of Hearing Medicine, Eye &ENT Hospital of Fudan University, Shanghai 200031, China
| | - Wenwei Luo
- Department of Otology and Skull Base Surgery, Eye &ENT Hospital of Fudan University, Shanghai 200031, China.,Shanghai Clinical Medical Center of Hearing Medicine, Eye &ENT Hospital of Fudan University, Shanghai 200031, China
| | - Ping Chen
- Department of Cell Biology, Emory University, Atlanta, GA 30322, USA
| | - Fanglu Chi
- Department of Otology and Skull Base Surgery, Eye &ENT Hospital of Fudan University, Shanghai 200031, China.,Shanghai Clinical Medical Center of Hearing Medicine, Eye &ENT Hospital of Fudan University, Shanghai 200031, China
| | - Dongdong Ren
- Department of Otology and Skull Base Surgery, Eye &ENT Hospital of Fudan University, Shanghai 200031, China.,Shanghai Clinical Medical Center of Hearing Medicine, Eye &ENT Hospital of Fudan University, Shanghai 200031, China
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15
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Lee S, Jeong HS, Cho HH. Atoh1 as a Coordinator of Sensory Hair Cell Development and Regeneration in the Cochlea. Chonnam Med J 2017; 53:37-46. [PMID: 28184337 PMCID: PMC5299128 DOI: 10.4068/cmj.2017.53.1.37] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/26/2016] [Revised: 09/22/2016] [Accepted: 09/23/2016] [Indexed: 12/18/2022] Open
Abstract
Cochlear sensory hair cells (HCs) are crucial for hearing as mechanoreceptors of the auditory systems. Clarification of transcriptional regulation for the cochlear sensory HC development is crucial for the improvement of cell replacement therapies for hearing loss. Transcription factor Atoh1 is the key player during HC development and regeneration. In this review, we will focus on Atoh1 and its related signaling pathways (Notch, fibroblast growth factor, and Wnt/β-catenin signaling) involved in the development of cochlear sensory HCs. We will also discuss the potential applicability of these signals for the induction of HC regeneration.
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Affiliation(s)
- Sungsu Lee
- Department of Otolaryngology-Head and Neck Surgery, Chonnam National University Hospital, Chonnam National University Medical School, Gwangju, Korea.; Research Institute of Medical Sciences, Chonnam National University, Gwangju, Korea
| | - Han-Seong Jeong
- Research Institute of Medical Sciences, Chonnam National University, Gwangju, Korea.; Department of Physiology, Chonnam National University Medical School, Gwangju, Korea
| | - Hyong-Ho Cho
- Department of Otolaryngology-Head and Neck Surgery, Chonnam National University Hospital, Chonnam National University Medical School, Gwangju, Korea.; Research Institute of Medical Sciences, Chonnam National University, Gwangju, Korea
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16
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Luo WW, Han Z, Ren DD, Wang XW, Chi FL, Yang JM. Notch pathway inhibitor DAPT enhances Atoh1 activity to generate new hair cells in situ in rat cochleae. Neural Regen Res 2017; 12:2092-2099. [PMID: 29323051 PMCID: PMC5784360 DOI: 10.4103/1673-5374.221169] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/05/2022] Open
Abstract
Atoh1 overexpression in cochlear epithelium induces new hair cell formation. Use of adenovirus-mediated Atoh1 overexpression has mainly focused on the rat lesser epithelial ridge and induces ectopic hair cell regeneration. The sensory region of rat cochlea is difficult to transfect, thus new hair cells are rarely produced in situ in rat cochlear explants. After culturing rat cochleae in medium containing 10% fetal bovine serum, adenovirus successfully infected the sensory region as the width of the supporting cell area was significantly increased. Adenovirus encoding Atoh1 infected the sensory region and induced hair cell formation in situ. Combined application of the Notch inhibitor DAPT and Atoh1 increased the Atoh1 expression level and decreased hes1 and hes5 levels, further promoting hair cell generation. Our results demonstrate that DAPT enhances Atoh1 activity to promote hair cell regeneration in rat cochlear sensory epithelium in vitro.
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Affiliation(s)
- Wen-Wei Luo
- Department of Otolaryngology, Eye & ENT Hospital of Fudan University; Research Institute of Otolaryngology, Fudan University, Shanghai, China
| | - Zhao Han
- Department of Otolaryngology, Eye & ENT Hospital of Fudan University; Research Institute of Otolaryngology, Fudan University, Shanghai, China
| | - Dong-Dong Ren
- Department of Otolaryngology, Eye & ENT Hospital of Fudan University; Research Institute of Otolaryngology, Fudan University, Shanghai, China
| | - Xin-Wei Wang
- Department of Otolaryngology, Eye & ENT Hospital of Fudan University; Research Institute of Otolaryngology, Fudan University, Shanghai, China
| | - Fang-Lu Chi
- Department of Otolaryngology, Eye & ENT Hospital of Fudan University; Research Institute of Otolaryngology, Fudan University, Shanghai, China
| | - Juan-Mei Yang
- Department of Otolaryngology, Eye & ENT Hospital of Fudan University; Research Institute of Otolaryngology, Fudan University, Shanghai, China
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17
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Walters BJ, Diao S, Zheng F, Walters BJ, Layman WS, Zuo J. Pseudo-immortalization of postnatal cochlear progenitor cells yields a scalable cell line capable of transcriptionally regulating mature hair cell genes. Sci Rep 2015; 5:17792. [PMID: 26639154 PMCID: PMC4671002 DOI: 10.1038/srep17792] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/03/2014] [Accepted: 10/14/2015] [Indexed: 12/17/2022] Open
Abstract
The mammalian cochlea is a highly specialized organ within the inner ear. Sensory hair cells (HC) in the cochlea detect and transduce sound waves into electrical impulses that are sent to the brain. Studies of the molecular pathways regulating HC formation are hindered by the very sparse nature of HCs, where only ~3300 are found within an entire mouse cochlea. Current cell lines mimic certain aspects of HCs but lack terminal HC marker expression. Here we successfully “pseudo-immortalized” cochlear progenitor cells using the “conditional reprogramming” technique. These cells, termed “Conditionally Reprogrammed Otic Stem Cells” (CR-OSC), are able to bypass the senescence inherent to cochlear progenitor cells without genetic alterations, allowing for the generation of over 15 million cells from a single cochlea. These cells can be differentiated and up-regulate both early and terminal differentiation genes associated with HCs, including the terminal HC differentiation marker prestin. CR-OSCs also respond to known HC cues, including upregulation of HC genes in response to Atoh1 overexpression, and upregulation of prestin expression after thyroid hormone application. Overall, we describe the creation of a HC line capable of regulated expression of HC genes that can easily be recreated in any laboratory from any mouse of interest.
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Affiliation(s)
- Brandon J Walters
- Dept. of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Shiyong Diao
- Dept. of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Fei Zheng
- Dept. of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Bradley J Walters
- Dept. of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Wanda S Layman
- Dept. of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
| | - Jian Zuo
- Dept. of Developmental Neurobiology, St. Jude Children's Research Hospital, Memphis, TN 38105, USA
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18
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Atkinson PJ, Huarcaya Najarro E, Sayyid ZN, Cheng AG. Sensory hair cell development and regeneration: similarities and differences. Development 2015; 142:1561-71. [PMID: 25922522 DOI: 10.1242/dev.114926] [Citation(s) in RCA: 104] [Impact Index Per Article: 11.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/16/2022]
Abstract
Sensory hair cells are mechanoreceptors of the auditory and vestibular systems and are crucial for hearing and balance. In adult mammals, auditory hair cells are unable to regenerate, and damage to these cells results in permanent hearing loss. By contrast, hair cells in the chick cochlea and the zebrafish lateral line are able to regenerate, prompting studies into the signaling pathways, morphogen gradients and transcription factors that regulate hair cell development and regeneration in various species. Here, we review these findings and discuss how various signaling pathways and factors function to modulate sensory hair cell development and regeneration. By comparing and contrasting development and regeneration, we also highlight the utility and limitations of using defined developmental cues to drive mammalian hair cell regeneration.
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Affiliation(s)
- Patrick J Atkinson
- Department of Otolaryngology - Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Elvis Huarcaya Najarro
- Department of Otolaryngology - Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Zahra N Sayyid
- Department of Otolaryngology - Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA
| | - Alan G Cheng
- Department of Otolaryngology - Head and Neck Surgery, Stanford University School of Medicine, Stanford, CA 94305, USA
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19
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Yang XY, Jin K, Ma R, Yang JM, Luo WW, Han Z, Cong N, Ren DD, Chi FL. Role of the planar cell polarity pathway in regulating ectopic hair cell-like cells induced by Math1 and testosterone treatment. Brain Res 2015; 1615:22-30. [DOI: 10.1016/j.brainres.2015.04.017] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/29/2014] [Revised: 04/07/2015] [Accepted: 04/10/2015] [Indexed: 11/17/2022]
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20
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Mellott AJ, Devarajan K, Shinogle HE, Moore DS, Talata Z, Laurence JS, Forrest ML, Noji S, Tanaka E, Staecker H, Detamore MS. Nonviral Reprogramming of Human Wharton's Jelly Cells Reveals Differences Between ATOH1 Homologues. Tissue Eng Part A 2015; 21:1795-809. [PMID: 25760435 DOI: 10.1089/ten.tea.2014.0340] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/27/2023] Open
Abstract
The transcription factor atonal homolog 1 (ATOH1) has multiple homologues that are functionally conserved across species and is responsible for the generation of sensory hair cells. To evaluate potential functional differences between homologues, human and mouse ATOH1 (HATH1 and MATH-1, respectively) were nonvirally delivered to human Wharton's jelly cells (hWJCs) for the first time. Delivery of HATH1 to hWJCs demonstrated superior expression of inner ear hair cell markers and characteristics than delivery of MATH-1. Inhibition of HES1 and HES5 signaling further increased the atonal effect. Transfection of hWJCs with HATH1 DNA, HES1 siRNA, and HES5 siRNA displayed positive identification of key hair cell and support cell markers found in the cochlea, as well as a variety of cell shapes, sizes, and features not native to hair cells, suggesting the need for further examination of other cell types induced by HATH1 expression. In the first side-by-side evaluation of HATH1 and MATH-1 in human cells, substantial differences were observed, suggesting that the two atonal homologues may not be interchangeable in human cells, and artificial expression of HATH1 in hWJCs requires further study. In the future, this line of research may lead to engineered systems that would allow for evaluation of drug ototoxicity or potentially even direct therapeutic use.
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Affiliation(s)
- Adam J Mellott
- 1Bioengineering Graduate Program, University of Kansas, Lawrence, Kansas
| | | | - Heather E Shinogle
- 3Microscopy and Analytical Imaging Lab, University of Kansas, Lawrence, Kansas
| | - David S Moore
- 3Microscopy and Analytical Imaging Lab, University of Kansas, Lawrence, Kansas
| | - Zsolt Talata
- 4Department of Mathematics, University of Kansas, Lawrence, Kansas
| | - Jennifer S Laurence
- 1Bioengineering Graduate Program, University of Kansas, Lawrence, Kansas.,5Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, Kansas
| | - M Laird Forrest
- 1Bioengineering Graduate Program, University of Kansas, Lawrence, Kansas.,5Department of Pharmaceutical Chemistry, University of Kansas, Lawrence, Kansas
| | - Sumihare Noji
- 6Department of Life Systems, Institute of Technology and Science, The University of Tokushima, Minami-Jyosanjima-cho, Tokushima, Japan
| | - Eiji Tanaka
- 7Department of Orthodontics and Dentofacial Orthopedics, Institute of Health Biosciences, The University of Tokushima Graduate School, Kuramoto-cho, Tokushima, Japan
| | - Hinrich Staecker
- 1Bioengineering Graduate Program, University of Kansas, Lawrence, Kansas.,8Department of Otolaryngology, Head and Neck Surgery, University of Kansas Medical Center, Kansas City, Kansas
| | - Michael S Detamore
- 1Bioengineering Graduate Program, University of Kansas, Lawrence, Kansas.,9Department of Chemical and Petroleum Engineering, University of Kansas, Lawrence, Kansas
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21
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Richardson RT, Atkinson PJ. Atoh1 gene therapy in the cochlea for hair cell regeneration. Expert Opin Biol Ther 2015; 15:417-30. [DOI: 10.1517/14712598.2015.1009889] [Citation(s) in RCA: 38] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
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22
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Mulvaney JF, Amemiya Y, Freeman SD, Ladher RK, Dabdoub A. Molecular cloning and functional characterisation of chicken Atonal homologue 1: a comparison with human Atoh1. Biol Cell 2015; 107:41-60. [PMID: 25412697 DOI: 10.1111/boc.201400078] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/21/2014] [Accepted: 11/20/2014] [Indexed: 12/19/2022]
Abstract
BACKGROUND INFORMATION The vertebrate basic helix-loop-helix transcription factor Atoh1 is essential for maturation and survival of mechanosensory hair cells of the inner ear, neurogenesis, differentiation of the intestine, homeostasis of the colon and is implicated in cancer progression. Given that mutations in Atoh1 are detected in malignant tumours, study of functionally different Atoh1 alleles and homologues might yield useful avenues for investigation. The predicted sequence of chicken Atoh1 (cAtoh1) has large regions of dissimilarity to that of mammalian Atoh1 homologues. We hypothesise that cAtoh1 might have intrinsic functional differences to mammalian Atoh1. RESULTS In this study, we cloned and sequenced the full open reading frame of cAtoh1. In overexpression experiments, we show that this sequence is sufficient to generate a cAtoh1 protein capable of inducing hair cell markers when expressed in nonsensory regions of the developing inner ear, and that morpholino-mediated knock-down using a section of the sequence 5' to the start codon inhibits differentiation of hair cells in the chicken basilar papilla. Furthermore, we compare the behaviour of cAtoh1 and human Atoh1 (hAtoh1) in embryonic mouse cochlear explants, showing that cAtoh1 is a potent inducer of hair cell differentiation and that it can overcome Sox2-mediated repression of hair cell differentiation more effectively than hAtoh1. CONCLUSIONS cAtoh1 is both necessary and sufficient for avian mechanosensory hair cell differentiation. The non-conserved regions of the cAtoh1 coding region have functional consequences on its behaviour.
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Affiliation(s)
- Joanna F Mulvaney
- Sunnybrook Research Institute, Sunnybrook Health Sciences Centre, Toronto, ON, M4N 3M5, Canada
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23
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Feng X, Qin Z. Molecular Analysis of Hair Cells in Sensorineural Hearing Loss. Audiol Neurootol 2014; 19:267-74. [DOI: 10.1159/000363683] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/26/2013] [Accepted: 05/15/2014] [Indexed: 11/19/2022] Open
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24
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Hair cell regeneration after ATOH1 gene therapy in the cochlea of profoundly deaf adult guinea pigs. PLoS One 2014; 9:e102077. [PMID: 25036727 PMCID: PMC4103851 DOI: 10.1371/journal.pone.0102077] [Citation(s) in RCA: 61] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2014] [Accepted: 06/15/2014] [Indexed: 12/20/2022] Open
Abstract
The degeneration of hair cells in the mammalian cochlea results in permanent sensorineural hearing loss. This study aimed to promote the regeneration of sensory hair cells in the mature cochlea and their reconnection with auditory neurons through the introduction of ATOH1, a transcription factor known to be necessary for hair cell development, and the introduction of neurotrophic factors. Adenoviral vectors containing ATOH1 alone, or with neurotrophin-3 and brain derived neurotrophic factor were injected into the lower basal scala media of guinea pig cochleae four days post ototoxic deafening. Guinea pigs treated with ATOH1 gene therapy, alone, had a significantly greater number of cells expressing hair cell markers compared to the contralateral non-treated cochlea when examined 3 weeks post-treatment. This increase, however, did not result in a commensurate improvement in hearing thresholds, nor was there an increase in synaptic ribbons, as measured by CtBP2 puncta after ATOH1 treatment alone, or when combined with neurotrophins. However, hair cell formation and synaptogenesis after co-treatment with ATOH1 and neurotrophic factors remain inconclusive as viral transduction was reduced due to the halving of viral titres when the samples were combined. Collectively, these data suggest that, whilst ATOH1 alone can drive non-sensory cells towards an immature sensory hair cell phenotype in the mature cochlea, this does not result in functional improvements after aminoglycoside-induced deafness.
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25
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Luo WW, Yang JM, Han Z, Yuan YS, Sheng HB, Liu X, Chi FL. Atoh1 expression levels define the fate of rat cochlear nonsensory epithelial cells in vitro. Mol Med Rep 2014; 10:15-20. [PMID: 24788407 PMCID: PMC4068718 DOI: 10.3892/mmr.2014.2202] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2013] [Accepted: 03/03/2014] [Indexed: 11/25/2022] Open
Abstract
Atonal homolog 1 (Atoh1) is a basic helix-loop-helix transcription factor that is essential for inner ear hair cell differentiation. Previous studies have reported that Atoh1 gene transfer induces the production of ectopic hair cell-like cells (EHCLCs). In the present study, the effect of different Atoh1 expression levels and the duration of EHCLC formation on the lesser epithelial ridge (LER) of cochleae was examined using a human adenovirus serotype 5 (Ad5) vector encoding atoh1 and the reporter gene EGFP. Different Ad5-EGFP-atoh1/Ad5-EGFP virus titers were added to cultured cochlear explants and EHCLCs were detected in the LER at various time points. The results demonstrated that GFP alone did not induce EHCLCs. By contrast, Atoh1 expression induced EHCLCs as early as 2.5–5 days following EGFP-atoh1 infection in the LER and depending upon the viral titer, the number of EHCLCs increased with time. Higher Ad5-EGFP-atoh1 titers induced enhanced Atoh1 expression, resulting in an increase in EHCLCs. Lower Ad5-EGFP-atoh1 titers required more time for EHCLC formation and very low titers of Ad5-EGFP-atoh1 induced only weak Atoh1 expression and did not trigger EHCLC formation. In conclusion, the present study utilized an appropriate Ad5-EGFP-atoh1 titer range to induce Atoh1 expression and the subsequent production of EHCLCs. The results revealed that the Atoh1 expression level defined the fate of LER cells as either EHCLCs or nonsensory epithelial cells. This evidence may provide an important guideline for future studies into gene therapy strategies for the treatment of deafness.
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Affiliation(s)
- Wen-Wei Luo
- Department of Otolaryngology‑Head and Neck Surgery, Eye and ENT Hospital of Fudan University, Xuhui, Shanghai 200031, P.R. China
| | - Juan-Mei Yang
- Department of Otolaryngology‑Head and Neck Surgery, Eye and ENT Hospital of Fudan University, Xuhui, Shanghai 200031, P.R. China
| | - Zhao Han
- Department of Otolaryngology‑Head and Neck Surgery, Eye and ENT Hospital of Fudan University, Xuhui, Shanghai 200031, P.R. China
| | - Ya-Sheng Yuan
- Department of Otolaryngology‑Head and Neck Surgery, Eye and ENT Hospital of Fudan University, Xuhui, Shanghai 200031, P.R. China
| | - Hai-Bin Sheng
- Department of Otolaryngology‑Head and Neck Surgery, Eye and ENT Hospital of Fudan University, Xuhui, Shanghai 200031, P.R. China
| | - Xiang Liu
- Department of Otolaryngology‑Head and Neck Surgery, Eye and ENT Hospital of Fudan University, Xuhui, Shanghai 200031, P.R. China
| | - Fang-Lu Chi
- Department of Otolaryngology‑Head and Neck Surgery, Eye and ENT Hospital of Fudan University, Xuhui, Shanghai 200031, P.R. China
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26
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Liu Q, Chen P, Wang J. Molecular mechanisms and potentials for differentiating inner ear stem cells into sensory hair cells. Dev Biol 2014; 390:93-101. [PMID: 24680894 DOI: 10.1016/j.ydbio.2014.03.010] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2014] [Revised: 03/15/2014] [Accepted: 03/18/2014] [Indexed: 12/31/2022]
Abstract
In mammals, hair cells may be damaged or lost due to genetic mutation, infectious disease, chemical ototoxicity, noise and other factors, causing permanent sensorineural deafness. Regeneration of hair cells is a basic pre-requisite for recovery of hearing in deaf animals. The inner ear stem cells in the organ of Corti and vestibular utricle are the most ideal precursors for regeneration of inner ear hair cells. This review highlights some recent findings concerning the proliferation and differentiation of inner ear stem cells. The differentiation of inner ear stem cells into hair cells involves a series of signaling pathways and regulatory factors. This paper offers a comprehensive analysis of the related studies.
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Affiliation(s)
- Quanwen Liu
- Institute of Cell and Development, College of Life Sciences, Zhejiang University, Hangzhou 310058, PR China
| | - Ping Chen
- Institute of Cell and Development, College of Life Sciences, Zhejiang University, Hangzhou 310058, PR China; Department of Cell Biology and Otolaryngology, Emory University School of Medicine, Atlanta, Georgia 30322, United States
| | - Jinfu Wang
- Institute of Cell and Development, College of Life Sciences, Zhejiang University, Hangzhou 310058, PR China.
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