[In vitro culture of greater epithelial ridge cells from rat cochleae].

Objective: To establish in vitro culture systems of greater epithelial ridge (GER) cells from rat cochlear and to investigate the characterization, growth pattern and ultrastructure of GER cells.
Methods: Using a combinatorial approach of enzymatic digestion and mechanical separation to allow isolation and culture of GER cells from P1 rat cochleae. The dissociated GER cells were cultured in serum-free or 10% fetal bovine serum DMEM respectively. BrdU, phalloidin, ZO1, calretinin and myosin VIIa immunostaining and scanning electron microscope observation were performed in GER cell cultures.
Results: The dissociated GER cell cultures showed positive to ZO1, phalloidin and BrdU staining, but negative to myosin VIIa and calretinin. They assumed a polygonal morphology which was similar to epithelial cells and grew in islands-like patches in medium containing 10% fetal bovine serum while forming spheres in serum-free medium. The GER cells presented significant ability to proliferate in both conditions. Scanning electron microscope showed that there was microvillus and centre bodies but not hair cell specific stereociliary bundles on the surface of GER cultures.
Conclusions: The GER cell cultures showed significant ability to proliferate and grew in islands-like patches in medium containing 10% fetal bovine serum while forming spheres in serum-free medium. The dissociated GER cells expressed epithelial cell specific marker but not marker of hair cells.