Specific targeting of brain endothelial cells using enhancer AAV vectors.

Brain endothelial cells (BECs) in brain vasculature are critical structural and functional components of the blood brain barrier (BBB). Adeno-associated virus (AAV) capsids have previously been genetically engineered to confer specificity to endothelial cells, but these capsids show limited endothelial cell specificity that varies by delivery conditions. We developed a set of new BEC-enhancer AAV vectors that specifically target BECs based on the cis-regulatory elements identified from single-cell epigenetic datasets. Ex vivo and in vivo characterization of BEC-enhancer AAVs in wild-type, Ai9 reporter, and Alzheimer's disease model mouse brains show their utility for high transduction selectivity of the BECs with little off-target transduction in the liver. Our BEC-enhancer AAVs target the brain vasculature by systemic administration and can be minimally invasive in terms of the route of administration. They are useful new tools for delivering genetic payloads specifically to BECs for normal and diseased brain studies.