Abstract
Purpose:
The ability to effectively deliver genetic material to vascular endothelial cells remains one of the greatest unmet challenges facing the development of gene therapies to prevent diseases with underlying vascular aetiology, such as diabetic retinopathy (DR) and neovascular age-related macular degeneration (NV-AMD). Herein, we assess the effectiveness of a rAAV2-based capsid mutant vector (Y272F, Y444F, Y500F, Y730F, T491V; termed, QuadYF+TV) with strong endothelial cell tropism at transducing the ocular vasculature following intravenous administration.
Methods:
QuadYF+TV expressing an EGFP or luciferase reporter gene from a vascular endothelial cell specific (VECadherin) promoter was injected intravenously at high titre (1012gp per animal) in wild type (C57Bl/6j and Balb/c) mice via the retro-orbital venous sinus; control animals received intravenous injection of either unmodified AAV2 or PBS. Systemic transgene expression was assessed by in vivo bioluminescence imaging (luciferase) with cellular tropism confirmed by post-mortem histopathology (EGFP); vector genome distribution was quantified by qPCR assay of tissue samples harvested from all organs and correlated to the observed expression levels.
Results:
Intravenous administration of QuadYF+TV.EGFP vector resulted in widespread transgene expression throughout the vasculature of most major organ systems, including the choroidal and retinal blood vessels of the eye. In vivo bioluminescence imaging of QuadYF+TV.Luciferase injected mice (n=9) revealed diffuse signal throughout the body and substantially reduced liver expression compared to unmodified AAV2 injected mice.
Conclusions:
Intravenous administration of QuadYF+TV vector resulted in effective transduction of retinal and choroidal blood vessels, in addition to vasculature of several organ systems. The ability to target the vascular endothelium efficiently represents a significant advance towards the development of AAV-mediated gene therapies for the treatment of retinal diseases stemming from underlying vascular dysfunction, such as DR and NV-AMD.