Spontaneous hair cell regeneration in the neonatal mouse cochlea in vivo

Development, Feb 2014

Loss of cochlear hair cells in mammals is currently believed to be permanent, resulting in hearing impairment that affects more than 10% of the population. Here, we developed two genetic strategies to ablate neonatal mouse cochlear hair cells in vivo. Both Pou4f3DTR/+ and Atoh1-CreERâ„¢; ROSA26DTA/+ alleles allowed selective and inducible hair cell ablation. After hair cell loss was induced at birth, we observed spontaneous regeneration of hair cells. Fate-mapping experiments demonstrated that neighboring supporting cells acquired a hair cell fate, which increased in a basal to apical gradient, averaging over 120 regenerated hair cells per cochlea. The normally mitotically quiescent supporting cells proliferated after hair cell ablation. Concurrent fate mapping and labeling with mitotic tracers showed that regenerated hair cells were derived by both mitotic regeneration and direct transdifferentiation. Over time, regenerated hair cells followed a similar pattern of maturation to normal hair cell development, including the expression of prestin, a terminal differentiation marker of outer hair cells, although many new hair cells eventually died. Hair cell regeneration did not occur when ablation was induced at one week of age. Our findings demonstrate that the neonatal mouse cochlea is capable of spontaneous hair cell regeneration after damage in vivo. Thus, future studies on the neonatal cochlea might shed light on the competence of supporting cells to regenerate hair cells and on the factors that promote the survival of newly regenerated hair cells.

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Spontaneous hair cell regeneration in the neonatal mouse cochlea in vivo

Brandon C. Cox 1 2 Renjie Chai 0 6 Anne Lenoir 2 5 Zhiyong Liu 2 4 LingLi Zhang 2 Duc-Huy Nguyen 0 Kavita Chalasani 0 Katherine A. Steigelman 2 4 Jie Fang 2 Edwin W. Rubel 3 Alan G. Cheng ( 0 Jian Zuo ) 2 0 Department of Otolaryngology-Head and Neck Surgery, Stanford University School of Medicine , Stanford, CA 94305 , USA 1 Department of Pharmacology, Southern Illinois University School of Medicine , Springfield, IL 62702 , USA 2 Department of Developmental Neurobiology, St. Jude Children's Research Hospital , Memphis, TN 38105 , USA 3 Virginia Merrill Bloedel Hearing Research Center, Department of Otolaryngology-Head and Neck Surgery, University of Washington School of Medicine , Seattle, WA, 98195-7923 , USA 4 Department of Anatomy and Neurobiology, University of Tennessee Health Science Center , Memphis, TN 38163 , USA 5 Universite Paris-Diderot, UFR Sciences du vivant , Paris 7, Paris , France 6 Key Laboratory for Developmental Genes and Human Disease, Ministry of Education, Institute of Life Sciences, Southeast University , Nanjing 210096 , China Edwin W. Rubel was omitted from the authorship of the paper. The correct author list and affiliations appears above. In addition the Acknowledgements and Author contributions sections should read as follows. - Acknowledgements We thank L. Tong and R. Palmiter (University of Washington) for Pou4f3DTR/+ mice and discussion; S. Baker (St. Jude) for Atoh1-CreERTM mice and discussion; R. Kageyama (Kyoto University) for Hes5-nlsLacZ mice; P. Chambon (Institut Genetique Biologie Moleculaire Cellulaire) for the CreERT2 construct; S. Heller (Stanford University) for the anti-espin antibody and critical reading, J. Corwin, J. Burns and other members of the Corwin laboratory (University of Virginia) as well as members of our laboratories for discussion and critical comments; S. Connell, V. Frohlich, Y. Ouyang and J. Peters (St. Jude) for expertise in confocal imaging; A. Xue, V. Nookala, N. Pham, A. Vu, G. Huang and W. Liu (Stanford University) for excellent technical support; and L. Boykins (University of Memphis), R. Martens and J. Goodwin (University of Alabama) for assistance and expertise in scanning electron microscopy. Author contributions B.C.C., R.C., E.W.R., A.G.C. and J.Z. developed the concepts or approach; B.C.C., R.C., A.L., Z.L., L.Z., D.-H.N., K.C., K.A.S., J.F., A.G.C. and J.Z. performed experiments or data analysis; B.C.C., R.C., A.G.C. and J.Z. prepared or edited the manuscript prior to submission. The authors apologise to readers for this mistake. STEM CELLS AND REGENERATION Spontaneous hair cell regeneration in the neonatal mouse cochlea in vivo Brandon C. Cox1,2,*, Renjie Chai3,4,*, Anne Lenoir1,5, Zhiyong Liu1,6, LingLi Zhang1, Duc-Huy Nguyen3, Kavita Chalasani3, Katherine A. Steigelman1,6, Jie Fang1, Alan G. Cheng3, and Jian Zuo1, ABSTRACT Loss of cochlear hair cells in mammals is currently believed to be permanent, resulting in hearing impairment that affects more than 10% of the population. Here, we developed two genetic strategies to ablate neonatal mouse cochlear hair cells in vivo. Both Pou4f3DTR/+ and Atoh1-CreERTM; ROSA26DTA/+ alleles allowed selective and inducible hair cell ablation. After hair cell loss was induced at birth, we observed spontaneous regeneration of hair cells. Fate-mapping experiments demonstrated that neighboring supporting cells acquired a hair cell fate, which increased in a basal to apical gradient, averaging over 120 regenerated hair cells per cochlea. The normally mitotically quiescent supporting cells proliferated after hair cell ablation. Concurrent fate mapping and labeling with mitotic tracers showed that regenerated hair cells were derived by both mitotic regeneration and direct transdifferentiation. Over time, regenerated hair cells followed a similar pattern of maturation to normal hair cell development, including the expression of prestin, a terminal differentiation marker of outer hair cells, although many new hair cells eventually died. Hair cell regeneration did not occur when ablation was induced at one week of age. Our findings demonstrate that the neonatal mouse cochlea is capable of spontaneous hair cell regeneration after damage in vivo. Thus, future studies on the neonatal cochlea might shed light on the competence of supporting cells to regenerate hair cells and on the factors that promote the survival of newly regenerated hair cells. INTRODUCTION Hair cells (HCs) regenerate in both the auditory and vestibular systems of non-mammalian vertebrates, leading to restoration of hearing and balance (Balak et al., 1990; Corwin and Cotanche, 1988; Lombarte et al., 1993; Ryals and Rubel, 1988). This process occurs by two mechanisms: direct transdifferentiation and mitotic regeneration. Direct transdifferentiation refers to a cell fate change when neighboring supporting cells (SCs) convert into HCs without cell division. Mitotic regeneration occurs when a SC first divides and, subsequently, one or bo (...truncated)


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Brandon C. Cox, Renjie Chai, Anne Lenoir, Zhiyong Liu, LingLi Zhang, Duc-Huy Nguyen, Kavita Chalasani, Katherine A. Steigelman, Jie Fang, Alan G. Cheng, Jian Zuo. Spontaneous hair cell regeneration in the neonatal mouse cochlea in vivo, Development, 2014, pp. 816-829, 141/4, DOI: 10.1242/dev.103036