Effect of over-expression of pigment epithelium derived factor(PEDF) on developing retinal vasculature in the mouse

[摘要] Purpose: Pigment epithelium derived factor (PEDF) is a secretedprotein with demonstrated anti-angiogenic properties, and with potentialapplication for the treatment of neovascular disease. Delivery ofpigment epithelium derived factor to the retina via virus mediated genetransfer has been shown to inhibit neovascularization in a number ofexperimental models. While pigment epithelium derived factor isendogenously expressed in the retina, its role in guiding normal vesseldevelopment and growth is not yet known. This study aimed to determinewhether over-expression of pigment epithelium derived factor alters thenormal pattern of retinal vessel development.Methods: Neonatal (age postnatal day 2 (P2)) CD1 mice were injectedsubretinally unilaterally with AAV2/1.CMV.PEDF while contralateral eyeswere injected subretinally with AAV2/1.CMV.EGFP as control. Cohorts ofanimals were sacrificed at P7 to P21 and the retinal vasculature wasco-labeled through fluorescein-dextran perfusion andimmunohistochemistry. Vascular size, localization, and structure wereanalyzed using light and confocal microscopy. Additional cohorts wereuse to obtain quantitative levels of pigment epithelium derived factorprotein through ELISA.Results: The extent of vessel growth from the optic disk toperiphery over time (i.e., the radius of retinal vasculature), and thearea of expansion of the neural retina were unaffected byover-expression of pigment epithelium derived factor to levels at least3.5 fold higher than endogenous levels. The thicknesses of the variousretinal layers were similar in AAV2/1.CMV.PEDF treated and controlinjected eyes. Three dimensional analysis of confocal images shows aslight delay in the rate of growth of vasculature into the deeper layersof the retina in pigment epithelium derived factor treated eyes comparedto EGFP treated control eyes. However, the normal differentiation ofvessels into arterioles, and venules, and the formation of a capillarynetwork continued to occur, achieving normal and complete maturation ofvascular structure by P21.Conclusions: Over-expression of pigment epithelium derived factor inthe developing retina exerted no marked or permanent effects on retinalvessel growth and differentiation. The findings are relevant to thesafety of the potential therapeutic use of pigment epithelium derivedfactor in human retinal disease.

[学科分类] 生物化学/生物物理