Protection of retinal ganglion cells from ischemia-reperfusion injury by electrically applied Hsp27

PURPOSE. To determine whether the Hsp27 protein can rescue retinal ganglion cells (RGCs) of rats from ischemia-reperfusion injury. METHODS. Retinal ischemia was induced in rats by clamping the ophthalmic artery within the dural sheath of the optic nerve. Immediately after removing the clamp and beginning the reperfusion, Hsp27 protein solution was injected into the vitreous, and electroporation was applied. To determine whether Hsp27 entered the RGCs, anti-Hsp27 immunohistochemistry was performed. The retinal damage was evaluated by counting the number of RGCs retrogradely labeled by 1,1′-dioctadecyl-3,3,3′3′-tetramethylindocarbocyanine percholorate (diI) injected into the superior colliculus, and also by comparing the ratio of TUNEL-positive to all RGCs in the RGC layer. RESULTS. Electroporation successfully delivered Hsp27 protein into RGCs. In the Hsp27 electroinjected group, the number of RGCs 7 days after ischemia-reperfusion was significantly higher than in the control groups. The ratio of TUNEL-positive cells to all RGCs was lower in the group electroinjected with Hsp27 protein. CONCLUSIONS. Electroporation of Hsp27 protein into RGCs increased the resistance of the RGCs to the apoptosis induced by ischemia-reperfusion injury.