Inhibitory Effect Of RGDs Peptide On Experimental Choroidal Neovascularization In A Rat Model

Part one: Quantitative Image Analysis of Experimental Laser-induced Choroidal NeovascularizationObjective To investigate the feasibility of diode laser-induced choroidal neovascularization (CNV) model in the Brown Norway rats and also to compare different detection methods of CNV in the rat. Methods 32 model rats were received a series of 10 laser lesions (532nm) per eye (525mw, 50μm, 0.05s).7days, 21 days, 35days and 63days after photo congulation, CNV is evaluated by fundus fluorescein angiography(FFA), indocyanine green angiography(ICGA), high molecular weight FITC-Dextran (MW 2x10~6) for high resolution angiography in RPE-choroid-sclera flat mounts and histopathologic examination. Results Leakage staining appeared in the FTA, ICGA showed that the disciformarea was filled with CNV. CNV was quantified by high resolution angiography in RPE-choroid-sclera flat mounts, light microscopy and immunohistochemical method. CNV was firstly appeared on day 7 after photocoagulation, reached the peak from day 21 to 35(P<0.001) and decreased significally after day 63(P<0.001). Conclusion This reproducible and quantifiable rat model is very useful for in vivo studies of angiogenesis and its modulation via viarious thrapy.Part two: Inhibitory Effect of RGDS Peptide on Experimental Choroidal Neovascularization in a Rat ModelObjective To investigate the efficacy and feasibility of RGDS (Arg-Gly-Asp-Ser) peptide (an α_v-integrin antagonist) in a rat model of laser-induced CNV. Methods Experimental choroidal neovascularization (CNV) was induced by laser photocoagulation in Brown Norway rats(50-um diameter, 0.05-second duration and 525-mw intensity). The rats were treated on days 7 with phosphate buffered saline(PBS) or 100, 300ug of RGDS peptide in PBS injectd intravitreally. On the 14th day after photocoagulation, CNV was observed by fundus fluorescein angiography (FFA) and indocyanine green angiography (ICGA). we evaluated the area of CNV by high molecular weight FITC-dextran(MW 2×10~6)for high resolution angiography in RPE-choroid-sclera flat mounts and the thickness microscopically on histologic sections. Neovascular vessels were detected and quantified by an-antibody against factor Ⅷ. Two eyes in every group were examined by transmission electron microscopy to assess retinal structural changes. Results In eyes treated with two injections of 300 or 100ug of RGDS peptide on the 14th day after laser photocoagulation, the development of CNV was significantly (P<0.001) inhibited in the area of CNV in RPE-choroid-Sclera flat mounts. Histologically, the thickness of the lesions was significantly(P<0.001) reduced in eyes that received 300 or100ug of RGDS peptide and immunoreactivity of factor Ⅷ in CNV showed significant difference (P<0.001) in eyes injected with RGDS peptide compared with control eyes. RGDS peptide reduced the area and the thickness of CNV in a dose-dependent manner. No evidence of toxicity was found in retina by transmission electorn microscopy in every group.Conclusious RGDS peptide effectively inhibited CNV progression in a rat model of laser-induced CNV, suggesting that this α_v-integrin antagonist may be beneficial in the treatment of CNV.