CHARACTERIZATION AND DEVELOPMENT OF AN INNER-EAR TYPE-I FIBROCYTE CELL-CULTURE

A method has been developed that allows successful maintenance of seco ndary cell cultures derived from explants of the cochlear lateral wall of young adult gerbils. The secondary cultures were characterized mor phologically with light and transmission electron microscopy and immun ocytochemically with protein markers specific to various lateral wall cell types. Structural studies revealed fusiform-shaped cells with a p aucity of cytoplasm surrounding the nucleus and slender processes. The cells showed little evidence of intercellular contact even when confl uent. The cultures were immunopositive for vimentin, carbonic anhydras e isozyme II, creatine kinase isozyme BB and smooth endoplasmic reticu lum Ca-ATPase, but lacked reactivity for cytokeratins and Na,K-ATPase. The results indicate that the cultures are comprised of type I fibroc ytes from the spiral ligament. These findings are the first to demonst rate that inner ear spiral ligament cells can be isolated and maintain ed in secondary culture while retaining many of their in vivo characte ristics. Based upon their location and content of ion transport enzyme s, type I fibrocytes are thought to be involved in the recycling of po tassium from perilymph into the stria vascularis. The establishment of this cell line provides a means to analyze the role of spiral ligamen t fibrocytes in maintenance of inner ear homeostasis.