VEGF-A165B is cytoprotective and antiangiogenic in the retina

Abstract

URPOSE. A number of key ocular diseases, including diabetic retinopathy and age-related macular degeneration, are characterized by localized areas of epithelial or endothelial damage, which can ultimately result in the growth of fragile new blood vessels, vitreous hemorrhage, and retinal detachment. VEGFA165, the principal neovascular agent in ocular angiogenic conditions, is formed by proximal splice site selection in its terminal exon 8. Alternative splicing of this exon results in an antiangiogenic isoform, VEGF-A165b, which is downregulated in diabetic retinopathy. Here the authors investigate the antiangiogenic activity of VEGF165b and its effect on retinal epithelial and endothelial cell survival. METHODS. VEGF-A165b was injected intraocularly in a mouse model of retinal neovascularization (oxygen-induced retinopathy [OIR]). Cytotoxicity and cell migration assays were used to determine the effect of VEGF-A165b. RESULTS. VEGF-A165b dose dependently inhibited angiogenesis (IC50, 12.6 pg/eye) and retinal endothelial migration induced by 1 nM VEGF-A165 across monolayers in culture (IC50, 1 nM). However, it also acts as a survival factor for endothelial cells and retinal epithelial cells through VEGFR2 and can stimulate downstream signaling. Furthermore, VEGF-A165b injection, while inhibiting neovascular proliferation in the eye, reduced the ischemic insult in OIR (IC50, 2.6 pg/eye). Unlike bevacizumab, pegaptanib did not interact directly with VEGF-A165b. CONCLUSIONS. The survival effects of VEGF-A165b signaling can protect the retina from ischemic damage. These results suggest that VEGF-A165b may be a useful therapeutic agent in ischemia induced angiogenesis and a cytoprotective agent for retinal pigment epithelial cells. © Association for Research in Vision and Ophthalmology.