PDGF-CC protects RGCs from axotomy-induced neuronal death. (A) In situ hybridization assay detected abundant PDGF-C expression in the retina mainly in the RGC layer and INL/ONL. Bar, 50 µm. (B) Western blot assay detected PDGF-CC expression in the retina as several forms because of different proteolytic processing. (C–E) Real-time PCR showed up-regulated expression of PDGF-C, PDGFR-α, and PDGFR-β, in the retinae after ONC using β-actin as an internal control (n = 6 eyes). (F, G, and L) PDGF-C deficiency led to fewer viable RGCs (blue) after ONC (n = 9 or 11 eyes). (H, I, L, and M) PDGF-C shRNA intravitreal injection decreased PDGF-C transcript level to <50% of normal level (M, n = 8 eyes) and led to fewer viable RGCs (blue) compared with that of the control group (H, I, and L, n = 7 eyes). (J–L) PDGF-CC protein intravitreal injection increased the number of viable RGCs (white) after ONC (n = 8 eyes). (N–P) Real-time PCR validated the genome-wide gene expression profiling data. PDGF-CC treatment down-regulated the expression of numerous apoptotic/cell death–related genes in retinae after ONC at different time points (N and O, n = 8 eyes) and in normal retina (P). (Q and R) PDGF-CC treatment up-regulated the expression of many neurotrophic/survival genes in ONC-injured retinae at different time points (n = 8 eyes). (S) No difference was found in EB extravasation in the retina between PDGF-C–deficient and wild-type mice (n = 14–16 eyes). (T) Intravitreal injection of PDGF-CC protein did not affect retinal permeability at different time points, whereas the same amount of BSA increased retinal permeability transiently (n = 8–10 eyes). Bars: (F–K) 20 µm. *, P < 0.05; **, P < 0.01. The data are represented as means ± SEM of the number of determinations. All experiments were repeated independently once (A–E and M–R) or twice (F–L) with similar results. Representative images (A, B, and F–I) or pooled data (C–E and M–R) are shown. Ch, choroid; IS/OS, inner/outer segment.