Abstract
Abstract: :
Purpose: PEDF is an important regulator of ocular angiogenesis. We investigated whether expression of PEDF by HC-Ad vector mediated gene transfer to RPE inhibits oxygen-induced retinopathy and laser-induced choroidal neovascularization and improves the survival of photoreceptors in relevant animal models of neoangiogenesis and retinal degeneration. Methods: A HC-Ad.PEDF vector was constructed to express human PEDF carrying a C-terminal 6-his tag. As control, a HC-Ad vector coding for the reporter gene enhanced green fluorescence protein (EGFP) was used. After subretinal injection of the HC-Ad vectors, the duration of transgene expression in RPE layer was monitored by scanning laser ophthalmoscopy, fluorescence microscopy and immunohistochemistry. Pathological choroidal vascularization was evaluated by labelling of newly formed blood vessels with PECAM-1 antibody and by the size of areas with neoangiogenesis. Pathological retinal vascularization was evaluated by FITC-angiography and the lenght of epiretinal blood vessels. The effect of genetically produced PEDF on the photoreceptor cell survival was tested in retinal dystrophic RCS rats. Results: Subretinal injection of HC-Ad vector coding for reporter gene EGFP resulted in stable and prolonged (6 months) expression in RPE cells without toxic effects and immune reactions due to the absence of viral gene expression. Subretinal injection of HC-Ad.PEDF resulted in prominent immunohistochemical staining of transduced RPE cells with anti-his antibody. Genetically produced PEDF released from these cells inhibited pathological choroidal vascularization in rats with laser-induced rupture of the Bruch's membrane and oxygen induced ischemic retinopathy. Subretinal delivery of HC-Ad.PEDF vector to 20 days old RCS rats did not rescue the photoreceptor cells as evaluated 2 months later, due probably to functional incompetence and/or degeneration of RPE layer in these animals. Conclusion: Increased expression in RPE cell layer of PEDF and/or other therapeutic gene by HC-Ad vector mediated gene transfer might provide an promising approach for the treatment of pathological ocular neovascularization.
Keywords: 419 gene transfer/gene therapy • 567 retinal pigment epithelium • 316 animal model