A Reproducible and Quantifiable Model of Choroidal Neovascularization Induced by Vegf After Subretinal Adenoviral Gene Transfer in the Rabbit

Abstract

Purpose: : To determine the effects of the vascular endothelial growth factor (VEGF)-A165 delivered using a high capacity adenoviral vector (HC Ad.VEGF-A) on vascular growth and pathological changes in the rabbit eye and to combine different detection methods of VEGF-A165 overexpression-induced neovascularization in the rabbit.

Methods: : HC Ad.VEGF-A165 was constructed and injected at 5x106 infectious units into the subretinal space of the rabbit eye. The development of neovascularization and the expression of HC Ad-transduced VEGF-A165 protein were followed up in vivo by scanning laser ophthalmoscopy, and fluorescein and indocyanine green angiographies and ex vivo by electron microscopy and immunohistochemistry four weeks after the injection.

Results: : In the present model, we observed a choroidal neovascularization (CNV) with leakage in 83% of the rabbit eyes. Our findings present clear indications that there is a significant effect on the endothelial cells of the choriocapillaris after the subretinal transduction of the retinal pigment epithelium (RPE) with VEGF-A165 vector. The choroidal endothelial cells are activated, endothel junctions open, the fenestration is minimised, while the endothelial cells augment the extracellular matrix, begin to migrate and infiltrate the Bruch’s membrane at the same time. They also proliferate and form pathological vessels in the subretinal space. Moreover, an increased expression of FGF and VEGF-A accompanied with stimulation of macrophages, retinal oedema and loss of photoreceptors were observed.

Keywords: gene transfer/gene therapy • age-related macular degeneration • vascular endothelial growth factor