A hypoxia-regulated retinal pigment epithelium-specific gene therapy vector reduces choroidal neovascularization in a mouse model.

BACKGROUND Wet age-related macular degeneration (wAMD) is characterized by the presence of choroidal neovascularization (CNV). Although there are some clinical drugs targeting vascular endothelial growth factor (VEGF) and inhibiting CNV, two major side effects limit their application, including excessive activity of anti-VEGF and frequent intraocular injections. To explore better treatment strategies, researchers developed a hypoxic modulator retinal pigment epithelium (RPE)-specific adeno-associated virus (AAV) vector expressing endostatin to inhibit CNV. However, the mechanism of endostatin is complex. Instead, sFlt-1 can inhibit VEGF-induced angiogenesis through two simple and clear mechanisms, giving rise to sequestration of VEGF and forming inactive heterodimer with the membrane-spanning isoforms of the VEGF receptor Flt-1 and kinase insert domain-containing receptor. OBJECTIVE In this study, we chose soluble fms-like tyrosine kinase-1 (sFlt-1) as a safer substitute to treat wAMD by inhibiting VEGF-induced angiogenesis. METHODS AAV2/8-Y733F-REG-RPE-sFlt-1 vector was delivered by intravitreal injection to the eyes of mice. AAV2/8-Y733F vector is a mutant of AAV2/8 vector, and REG-RPE promoter is a hypoxia-regulated RPE-specific promoter. Two animal models were used to evaluate the function of the vector. RESULTS In the cobalt chloride-induced hypoxia model, the results demonstrated that AAV2/8-Y733F-REG-RPE-sFlt-1 vector induced the expression of sFlt-1 gene in RPE cells through hypoxia. In the laser-induced CNV model, the results demonstrated that AAV2/8-Y733F-REG-RPE-sFlt-1 vector reduced laser-induced CNV. CONCLUSIONS Hypoxia regulated, RPE-specific AAV vector-mediated sFlt-1 gene is a hypoxia-regulated antiangiogenic vector for wAMD.