BASILAR PAPILLA EXPLANTS - A MODEL TO STUDY HAIR CELL REGENERATION-REPAIR AND PROTECTION

Explants of basilar papillae from 6-7 days posthatch chicks were cultu red in growth medium for a period of 1-8 days. Hair cells were counted following staining of stereocilia bundles with FITC-phalloidin, and t he percentage of hair cell survival was determined by comparison to co ntrol (i.e. uncultured) specimens. Hair cell integrity was evaluated b y scanning electron microscopy. Although previous studies have utilize d organotypic culture of the basilar papilla to assess cell proliferat ion and ototoxicity, viability and integrity of hair cells was documen ted for periods of up to only 2-3 days. Our results demonstrate substa ntive auditory hair cell viability for a period of 7 days in vitro. We describe a pattern of natural hair cell loss in organotypic culture t hat progresses along a proximal-distal, abneural-neural gradient, mimi cking the pattern of hair cell loss that occurs following ototoxic ins ult to the chick basilar papilla in vivo and the pattern we observed d uring a 48-h period of exposure of basilar papilla explants to an otot oxic dose of neomycin. Our results provide an important quantitative s tep for the use of organotypic culture of the chick basilar papilla as a purposeful model to investigate the process of hair cell regenerati on-repair in the avian auditory system.