Long-Term Retinal PEDF Overexpression Prevents Neovascularization in a Murine Adult Model of Retinopathy

Virginia Haurigot,Assumpcio Bosch,Jesus Ruberte,David Ramos,Albert Ribera,Fatima Bosch,Pilar Villacampa,Tailoi Chan-Ling

doi:10.1371/journal.pone.0041511

Abstract

Neovascularization associated with diabetic retinopathy (DR) and other ocular disorders is a leading cause of visual impairment and adult-onset blindness. Currently available treatments are merely palliative and offer temporary solutions. Here, we tested the efficacy of antiangiogenic gene transfer in an animal model that mimics the chronic progression of human DR. Adeno-associated viral (AAV) vectors of serotype 2 coding for antiangiogenic Pigment Epithelium Derived Factor (PEDF) were injected in the vitreous of a 1.5 month-old transgenic model of retinopathy that develops progressive neovascularization. A single intravitreal injection led to long-term production of PEDF and to a striking inhibition of intravitreal neovascularization, normalization of retinal capillary density, and prevention of retinal detachment. This was parallel to a reduction in the intraocular levels of Vascular Endothelial Growth Factor (VEGF). Normalization of VEGF was consistent with a downregulation of downstream effectors of angiogenesis, such as the activity of Matrix Metalloproteinases (MMP) 2 and 9 and the content of Connective Tissue Growth Factor (CTGF). These results demonstrate long-term efficacy of AAV-mediated PEDF overexpression in counteracting retinal neovascularization in a relevant animal model, and provides evidence towards the use of this strategy to treat angiogenesis in DR and other chronic proliferative retinal disorders.

Highlights

Pathological retinal neovascularization is a feature of diabetic retinopathy and other ocular disorders characterized by retinal hypoxia [1]
associated viral vectors of serotype 2 (AAV2) mediated expression of Pigment Epithelium Derived Factor (PEDF) in TgIGF-I retinas The tropism of AAV2 vectors after intravitreal injection has previously been described for wild-type mouse retina [3]
To determine whether the pathological features of TgIGF-I retinas [19,20] could alter the normal pattern of infection of AAV2 vectors, the expression of the reporter protein GFP was analysed after intravitreal delivery of AAV2-GFP (6.26107 vg/eye) in which the GFP gene was under the control of an ubiquitous promoter

Summary

Introduction

Pathological retinal neovascularization is a feature of diabetic retinopathy and other ocular disorders characterized by retinal hypoxia [1]. Due to retinal IGF-I accumulation, these mice show increased levels of intraocular VEGF and vascular alterations that progress from a non-proliferative retinopathy to neovascularization that causes retinal detachment [19,20] This model offers advantages compared to other commonly used models of retinal angiogenesis, such as the ischemia-induced retinopathy model, known as retinopathy of prematurity model (ROP), in which vessels regress at approximately 3 weeks of age [21]. PEDF mediated the down regulation of VEGF in TgIGF-I-treated retinas, contributing to the decrease of downstream effectors of retinal neovascularization These results demonstrate the long-term efficacy of AAV2-mediated PEDF gene transfer in an animal model in which the development of retinal neovascularization follows a disease progression that mimics the human pathology

Results

Discussion

Materials and Methods