A targeted vector for brain endothelial cell gene delivery and cerebrovascular malformation modelling.

Defects in brain endothelial cells (brainECs) can cause severe cerebrovascular malformations, including arteriovenous malformation (AVM) and cerebral cavernous malformation. The lack of appropriate tools for cerebrovascular disease modelling and local genetic manipulation of the brain vasculature hinders research on cerebrovascular malformations. Here we develop a recombinant adeno-associated virus (rAAV) tool termed miniBEND (rAAV-based mini-system for brain endothelial cells, rAAV-miniBEND), which combines a minimal promoter and an optimized cis-acting element isolated from the mouse gene Tek. This system activates gene expression specifically in mouse and rat brainECs. rAAV-miniBEND achieved high-efficiency and high-specificity gene expression in brainECs through intracranial injection at various developmental stages and through intravenous administration at all postnatal stages in mice. Furthermore, we used rAAV-miniBEND to model sporadic cerebral cavernous malformations mediated by MAP3K3I441M and AVMs mediated by BrafV600E. Somatic expression of BrafV600E in brainECs induced an AVM phenotype, revealing that brainEC proliferation is important for AVM development. Thus, our rAAV-miniBEND system provides a widely applicable tool for cerebrovascular disease modelling and local or global brainEC gene delivery.