Downregulation of Vascular Endothelial Growth Factor and Integrin ß3 by Endostatin in a Mouse Model of Retinal Neovascularization

Abstract

Abstract: : Purpose: Retinal neovascularization is among the leading causes of vision impairment throughout the world. Intraocular expression of vascular endothelial growth factor (VEGF), an angiogenic protein, and integrins, a group of cell adhesion molecules is closely correlated with neovascularization in such neovascular diseases. This study is to determine the effect of endostatin, a potent anti–angiogenic factor, on gene expression of VEGF and integrinß₃ in a mouse model of oxygen–induced retinopathy. Methods: In a mouse model of retinal neovascularization, C57BL/6 mice were given intravitreous injections of 1.0µg endostatin at P12. At P17, eyes from hyperoxia group and normoxia group were enucleated after intracardiac perfusion with fluorescein–dextran. Retinas were flat–mounted. Retinal total RNA was extracted from the endostatin–treated group mice and the hyperxia group mice at P₁₇ , the expression of retinal VEGF and integrinß₃ mRNA levels were measured by real–time quantitative PCR. Results: Retina flat mounts showed the retina of P₁₇ normoxia mouse had two layers of vessel that extended from the optic nerve to the periphery. The retina of P₁₇ hyperoxia mouse had nonperfused area in center, and tortuous, dilated vessels between perfused and nonperfused area. Where in the edostatin–treated mouse, the retinal vessels were almost normal. The retinal total RNA from retina was detected by agarose 1% gel electrophoresis No unexpected band is detected which indicates the purity of the RNA was high. According to each standard curve, the level of VEGF and integrinß₃ was examined. Analysis of twelve separate experiments revealed a 3.5–fold decrease in VEGF levels between hyperoxia mice and edostatin–treated mice (p<0.01) and a 2.5– fold decrease in integrinß₃ levels between hyperoxia mice and endostatin–treated mice (p<0.01). Conclusions: These data suggest that intraocular expression of VEGF and integrinß₃ mRNA is down–regulated by endostatin, which may provide a new therapeutic approach for ocular neovascularization.

Keywords: retinal neovascularization • gene/expression