Cellular interactions as a response to injury in the organ of Corti in culture

We discovered and described ultrastructurally the intricate relationships between the sensory cells and their supporting cells in cultures of the organ of Corti following laser beam irradiation. Injury was performed using a 440 nm nitrogen-dye pulse laser aimed at the cuticular plates of inner hair cells. Laser injury is compared with mechanical injury inflicted on the hair cell region by a pulled-glass pipette. Regardless of the type of injury, but depending on its severity, the surviving hair cells may: (1) lose their stereocilia but subsist at the surface of the organ; (2) retain contact with the reticular lamina but be overgrown by the processes of the supporting cells; or (3) become sequestered from the reticular lamina and internalized among the supporting cells, where they either remain dedifferentiated or regrow an apical process which regains contact with the surface of the organ. All supporting cells, including pillar and Deiters' cells, take part in wrapping their respective inner or outer hair cells. The supporting cells not only cover the injured sensory cells, but also invert their villi toward the maimed cuticular plates and release an extracellular matrix around them. We suggest that the supporting cells play a protective and trophic role in the recovery of injured hair cells. (C) 1997 ISDN.