Meeting Abstract
Some of the first evidence for regeneration of hair cells came from studies of the lateral line organs of fish and amphibians. These organs consist of mechanosensitive neuromasts distributed along the body surface. In Uredels after amputation of the tail new neuromasts are generated in the lateral line organ at the stump and migrate to form new organs as the tail regenerates (Stone, 1937). Studies by Jones and Corwin demonstrated that a low level of ongoing proliferation is dramatically up regulated after hair cells in the lateral line are destroyed by a laser (Jones and Corwin, 1993, 1996). Direct time-lapse recordings demonstrated that the regenerated hair cells rose from support cells (Jones and Corwin, 1993). A similar increase in mitotic proliferation of support cells occurs in fish after various types of ototoxic damage (Hernandez et al., 2007; Ma et al., 2008 and Williams and Holder, 2000), and the proliferating cells go on to replace the hair cells within 48hours of the insult. Similarly birds can replace hair cells in their inner ear sensory organs. In birds there is ongoing turnover in the utricle throughout life that can be up regulated in response to ototoxic injury. The situation in the auditory organ the basilar papilla in birds is different in that there is no ongoing replacement yet after ototoxic damage that destroys hair cells there is a robust proliferative response. Support cells re-enter the cell cycle within 16hours and new hair cells appear within 2-3 days. This replacement of hair cells restores function. In this presentation I will give an overview on recent finding regarding regeneration in mammalian inner ears. I will also describe some of our own studies on development of the sensory organs in the inner ear of the mouse and on our attempts to encourage regeneration.
