Basilar papilla explants: a model to study hair cell regeneration-repair and protection

Explants of basilar papillae from 6-7 days posthatch chicks were cultured in growth medium for a period of 1-8 days. Hair cells were counted following staining of stereocilia bundles with FITC-phalloidin, and the percentage of hair cell survival was determined by comparison to control (i.e. uncultured) specimens. Hair cell integrity was evaluated by scanning electron microscopy. Although previous studies have utilized organotypic culture of the basilar papilla to assess cell proliferation and ototoxicity, viability and integrity of hair cells was documented for periods of up to only 2 3 days. Our results demonstrate substantive auditory hair cell viability for a period of 7 days in vitro. We describe a pattern of natural hair cell loss in organotypic culture that progresses along a proximal-distal, abneural-neural gradient, mimicking the pattern of hair cell loss that occurs following ototoxic insult to the chick basilar papilla in vivo and the pattern we observed during a 48-h period of exposure of basilar papilla explants to an ototoxic dose of neomycin. Our results provide an important quantitative step for the use of organotypic culture of the chick basilar papilla as a purposeful model to investigate the process of hair cell regeneration-repair in the avian auditory system.