Development and Regeneration of Sensory Hair Cells
Hair cells are sensory receptors for hearing and balance, and for detection of water movement in aquatic animals. In mammals, the vast majority of hair cells are formed during embryogenesis and early postnatal development, whereas in other vertebrates hair cells are formed throughout life. Destruction of hair cells is caused by genetic, environmental, or aging factors and results in sensorineural deficits that are irreversible in humans. Research in the 1980s demonstrated that nonmammalian vertebrates fully replace hair cells after damage and recover function, suggesting hair cell regeneration may someday be coaxed in humans as a treatment for some forms of hearing and balance deficits. To facilitate this possibility, subsequent studies explored the molecular and cellular bases of hair cell formation during development and after damage in mature animals. This chapter reviews the findings in each of these areas, describing similarities and differences across species, sensory organs, and age. For instance, while mature mammals have a limited innate ability to regenerate hair cells in the vestibular inner ear, no hair cells are replaced in the cochlea. Further, although the transcription factor (Atoh1) drives cells toward a hair cell fate during development in all types of animals and in nonmammals after damage, it has limited ability to promote hair cell regeneration in mature mammals. Finally, we discuss some of the hurdles that remain, as well as new technologies that may be used to move the field forward.
KeywordsDevelopment Hair cell Inner ear Lateral line Molecular regulation Regeneration Supporting cell
Atonal homolog 1
High mobility group
Mechanistic target of rapamycin
The authors would like to acknowledge Edwin W Rubel as an exceptional mentor, colleague, and friend, and as one of the pioneers in the fields of both inner development and regeneration. The authors would also like to apologize for the many relevant references that were necessarily omitted because of space limitations.
Compliance with Ethics Requirements
Jennifer Stone declares that she has no conflict of interest.
Matthew Kelley declares that he has no conflict of interest.
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