Specific induction of FABP4 in neovessels during OIR.

(A) qPCR quantification of FABP4 mRNA in total retinas from P12 to P17 in control (RA = room air) and OIR WT mice. Results are expressed as RE (relative expression) normalized to housekeeping genes (mean ± SEM, n = 3–4). FABP4 mRNA is significantly induced during the angiogenic phase of OIR. (B) Quantification of FABP4 protein expression in P17 RA control and OIR retinas by immunoblot and densitometry analysis (mean ± SEM, n  =  6) confirmed up-regulation of FABP4 expression during pathological neovascularization. (C) Quantification of circulating FABP4 demonstrated a significant decrease of serum FABP4 levels in OIR P17 WT mice compared to control room air (RA). Results are presented as mean ± SEM based on n = 3–4 individual animals. (D) FABP4 distribution was determined on P17 retina flat-mounts from OIR animals co-stained with the pan-endothelial marker BS1. FABP4 is expressed in neovascular tufts (arrowheads) and absent from adjacent normal blood vessels (arrows). Specificity of the FABP4 staining is confirmed using FABP4^−/− retina. Scale bar is 100 µm.