Pigment epithelium-derived factor protects cultured retinal neurons against hydrogen peroxide-induced cell death

Pigment epithelium-derived factor (PEDF) is a neurotrophic protein synthesi zed and secreted by retinal pigment epithelial (RPE) cells in early embryog enesis and has been shown to be present in the extracellular matrix between the RPE cells and the neural retina. It induces neuronal differentiation a nd promotes survival of neurons of the central nervous system from degenera tion caused by serum withdrawal or glutamate cytotoxicity, Because the role of PEDF in the retina is still unknown, we examined its ability to protect cultured retinal neurons against hydrogen peroxide (H2O2)-induced cell dea th. Retinas of 0-2-day-old Sprague-Dawley rats were isolated and dissociate d, and the neurons were maintained for 2 weeks in a synthetic serum-free me dium. Immunocytochemical labeling showed that 50-60% of the cultured cells were rod photoreceptors. Treatment with H2O2 induced significant death of r etinal neurons in a dose- and time-dependent manner, Pretreatment with PEDF prior to insult greatly attenuated H2O-induced cytotoxicity, and its effec t was shown to be dose dependent, Cytotoxicity was determined by 3,(4,5-dim ethylthiazol-2-yl)2,5-diphenyl-tetrazolium bromide and lactate dehydrogenas e assays, and apoptotic cell death was evaluated by the TdT-mediated digoxi genin-dUTP nick-end labeling assay. The present study also showed that H2O2 -induced retinal neuron death was by apoptosis that could be inhibited by P EDF, Combination of PEDF with basic fibroblast growth factor, brain-derived neurotrophic factor, or ciliary neurotrophic factor improves the protectio n. These data strongly suggest that PEDF is a potential neuroprotective age nt in the treatment of retinal degeneration. (C) 1999 Wiley-Liss, Inc.