International Session 1 Otology-Basic 1

Artificially inducing differentiation of inner ear stem cells in the cochlea is considered for the treatment of sensorineural hearing loss, because spontaneous hair cell regeneration is not observed in the mammalian cochlea.However, the long-time changes in stem cell potency due to aging and the difference in aging of stem cell potency after hair cell damage are not fully understood.We targeted Nestin, a neural stem cell marker in the central nervous system, and we detected the presence of stem cell potency in the mouse cochlea with Nestin-EGFP(enhanced green fluorescent protein)transgenic mice.We examined the cochlea of mice on the following postnatal days(P) : P30, P100, P150, P200, and P300.Mice of each age were divided into two groups; noise-exposure groups were exposed to 121dB of white noise for two hours and control groups were not exposed.We evaluated hearing by auditory brain response before and after noise exposure in all mice.We report the change of hearing thresholds and Nestin expression in the cochlea, especially spiral ganglion and organ of Corti, after noise exposure by using immune staining, and the difference of these by age in detail.