Abstract
w3-1 Progress towards understanding the basic mechanisms of angiogenesis, the formation of new blood vessels from existing vasculature, and therapies to control it have been limited by the lack of tools to measure angiogenesis in appropriate living tissues. While in vivo angiogenesis assays provide the best environment to follow angiogenesis, most assays are tempered by the inherent difficulty in obtaining reproducible data. Surgical methods induce inflammatory response and local variations in the site of implants can impact the outcome of the assay. The key elements of better assays should focus on approaches that can measure growth over time and minimize artifacts induced by experimental manipulation. Using multi-photon intra-vital imaging, it is possible to repeatedly image (Z-series) the same area over a period of days or even weeks.The multi-photon excitation produces the lowest photon dose in the sample of any imaging modality.These abilities, coupled with high spatial resolution achievable deep (0.5 mm) into living tissue allows non-invasivemonitoring of vessel growth over time.We are developing the technology to visualize the behavior and growth of blood vessels of mice after treatment with Vascular Endothelial Growth Factor delivered though direct injection of protein and by expression of endogenous growth factor in keratinocytes. Transgenic mice expressing GFP (Green Fluorescent Protein) driven by the Tie II promoter or direct injection of dextran-conjugated fluorophores enable the visualization of blood vessel structure are imaged and mapped over time.