Subconjunctival gene delivery of the transcription factor GA-binding protein delays corneal neovascularization in a mouse model

Abstract

Corneal neovascularization can reduce visual acuity. GA-binding protein (GABP) is a transcription factor that regulates the expression of target genes including vascular endothelial growth factor (VEGF) and roundabout4 (Robo4), which participate in pathologic angiogenesis. We assessed whether intraocular injection of the GABP gene affects the growth of new corneal blood vessels in a mouse ocular neovascularization model. Transfection of human GABPalpha and GABPbeta gene (GABPalpha/beta) into human conjunctival epithelial cells resulted in decreased VEGF and Robo4 expression. Three groups of mice underwent chemical and mechanical denudation of the corneal epithelium. Subsequently, two groups were administered subconjunctival injection of lipoplexes carrying plasmid DNA encoding for human GABPalpha/beta or an empty plasmid DNA at 1-week intervals. The third group served as an experimental control. In vivo delivery of human GABPalpha/beta into mouse neovascularized cornea reduced VEGF and Robo4 gene expression. Biomicroscopic examination showed that, at 1 week after one or two injections, GABPalpha/beta-treated eyes had significantly less neovascularized corneal area than did eyes treated with the empty vector. Histologic examination showed significantly less vascularized area and fewer blood vessels in the GABP-treated group at 1 week after injections. However, these angiosuppressive effects were weakened at 2 weeks after injections. Our results indicate that subconjunctival GABP gene delivery delays corneal neovascularization for up to 2 weeks in a mouse model of deliberate corneal injury.