Morphology and rate of apoptosis in cochlear hair cells in vitro

Objective To investigate the morphology and rate of apoptosis in normal cochlear hair cells in vitro.Methods Twelve healthy guinea pigs were used for the study,divided into two groups(each 6 animals, 12 ears).The cochlear hair cells were isolated from strips of the organ of corti in Hank′s solution after reacting with collagenuse.According to the Zenner′s viability criteria of isolated hair cells and morphology of apoptosis cells,the number of the isolated viable cochlear hair cells and that of apoptosis in cochlear hair cells were counted at various times.Results(1)There were morphologic differences between the apoptosis cells and the viable cochlear hair cells.The apoptosis hair cells presented membrane shrinkage and spraining with reduced refractive power.The cilium of the hair cell became bob or down,Brown′s movement was found in cytoplasm.The nuclear location was normal.Under the fluorescene microscope,the apoptosis of cochlear hair cells showed red or red-yellow fluorescene,and the membrane was not broken.(2)The number and rate of apoptosis of isolated cochlear hair cells were increased with the isolation time.The rate of apoptosis of hair cells was(4.83±1.96)% at 1h after isolation;that at 4h was(31.15±6.25)%.Statistic analysis showed that the rate of apoptosis of isolated cochlear hair cells in various periods had significant difference(P0.05).Conclusions(1)The apoptosis of isolated cochlear hair cells had specifically morphologic changes in vitro,which was different from the necrosis or viable in cochlear hair cells.(2)The rate of apoptosis of cochlear hair cells was increased with the isolation time.