The long-term objectives of this proposal are to explore the roles of angiogenesis in the brain, especially the role of brain arteriovenous malformations (BAVMs). We have intensively studied BAVM tissue removed during surgery. We will continue this study and develop an in vivo animal model of non-tumor angiogenesis relevant to cerebrovascular diseases including BAVMs. In vivo gene transfer into the brain with adenoviral vectors provides a useful tool inducing focal, non-tumor angiogenesis in the adult rodent brain. The PI has used this technique to induce stable overexpression of a variety of genes in the mouse brain. We hypothesize that adenoviral-mediated vascular endothelial growth factor (VEGF) gene transduction into the mouse brain induces VEGF overexpression. VEGF signaling, combined with VEGF-induced upregulation of the angiopoietin/Tie-2 signaling pathway, stimulates focal vascular network formation. Furthermore, transforming growth factor beta-1 (TGF-b1) activates TGF-b1, ALK-5, and Smad 2/3 signal pathways, promoting regional angiogenesis formation in the brain tissue.
The specific aims of this proposal are to determine: 1) whether VEGF protein production will be increased following adenoviral-VEGF (AdVEGF) gene transfer in the adult mouse brain, and whether overexpression of VEGF will induce focal clusters of microvasculature formation; 2) whether TbR-ll, ALK5, and Smad 2/3 will be upregulated in the TGF-bl transgenic mouse brain following AdVEGF gene transduction. Furthermore, to quantify whether endothelial cell proliferation and support cell differentiation will be increased, and finally, to identify how mature these neo-microvasculature are in the mouse brain with both TGF-b1 and VEGF overexpression. The experimental components include: 1) highly reproducible adenoviral vector gene transfer in mice; 2) specific VEGF and TGF-b1 pathway detection; and 3) using unique TGF-b transgenic mice. Combining these genetic techniques may lead to the development of a novel, reproducible, and useful animal model. This non-tumor angiogenesis rodent preparation will serve as a model of disordered human cerebral angiogenesis, leading relatively quickly to the ability to test new therapeutic approaches for cerebrovascular disorders.
