Interactions between Endostatin and Vascular Endothelial Growth Factor (VEGF) and Inhibition of Choroidal Neovascularization

This study was designed to evaluate the inhibitory effect of endostatin on choroidal neovascularization (CNV) in laser-induced rat model. Choroidal neovascularization was induced in Brown Norway (BN) rats by diode-laser photocoagulation. Rats were randomly divided into five groups (10 animals in each group): endostatin 20mg/kg group, endostatin 10mg/kg group, laser injury group, normal saline group and blank control group. The animals were treated with endostatin, normal saline, laser injury or without treatment on day 0 to day 13 after laser photocoagulation. On day 7 and 14 after laser photocoagulation, the CNV formation was assessed by fluorescein angiography and histopathological analysis. VEGF expression in retina was determined by immunohistochemical assay. In two endostatin groups, the incidence of CNV formation and the intensity of fluorescein leakage were reduced compared with the two control groups. No significant difference was found between laser injury group and normal saline group. The expression of VEGF reached peak at day 7 and then decreased from day 14 after photocoagulation. The expression of VEGF was significantly reduced in the two endostain groups than laser injury group in a dose-dependent way. Endostatin can inhibit the formation of experimental CNV in the rat. Down-regulation of VEGF expression could be one of the mechanisms underlying the inhibition of CNV by endostatin.