Direct protective effect of PDGF-CC on cultured neurons. (A–C) PDGF-CC treatment significantly decreased H₂O₂-induced apoptosis of the RGC5 cells measured by TUNEL staining (green; A and B) and increased their survival when the cells were cultured in serum-free medium (C). (D–F) PDGF-CC treatment increased survival of retinal neural progenitor cells (islet1⁺; red) when cultured in serum-free medium. (G–I) PDGF-CC treatment decreased hypoxia- and glucose deprivation–induced apoptosis in primary cortical neurons measured by TUNEL staining (green). (J–L) PDGF-CC treatment increased survival of TH⁺ neurons cultured in serum-free medium measured by TH staining (red). (M–O) PDGF-CC treatment increased survival of TH⁺ neurons measured by TH staining (red) when the neurons were stressed with neurotoxin 6-OHDA. Bars, 10 µm. *, P < 0.05; **, P < 0.01; ***, P < 0.001. The data are represented as means ± SEM of the number of determinations. All experiments were repeated independently twice with similar results. Representative images and experiments are shown.