(194c) Bionanotechnology to Guide Vessel Sprouting

Vascular endothelial growth factor (VEGF) is known to activate proliferation,  migration,  and survival pathways in endothelial cells through phosphorylation of VEGF receptor-2 (VEGFR-2). VEGF has been incorporated into biomaterials through encapsulation,  electrostatic sequestration,  and covalent attachment,  but the effect of these presentation strategies on VEGF signaling and endothelial cell sprouting has not been thoroughly investigated. In our laboratory, we investigate if the manner in which VEGF is presented from a scaffold to endothelial cells influences the phosphorylation of VEGFR-2 and the architecture of the blood vessels formed. We used three different VEGF presentations to study their role of VEGFR-2 signaling and vessel sprouting: covalently bound (Vc),  covalently bound and clustered (cVc),  and sustained release from nanocapsules  (nV). We covalently bound VEGF to either self-assembled monolayers on gold to make Vc or to polymeric nanoparticles to make cVc. To make nV we used in situ polymerization to polymerize a plasmin degradable nanogel around the protein. We found that covalently bound VEGF (Vc) is able to phosphorylate VEGFR-2 (VR-2) to the same extent as soluble VEGF (Vs) in endothelial cells (EC),  but that the mode of VEGF presentation alters the tyrosine residues that are phosphorylated,  the time course of phosphorylation,  and the resulting downstream signaling. Using cVc and an EC branching assay or CAM assay we found that VEGF clusters led to an increase in EC sprout branching,  thickness,  and total vessel network length compared to soluble VEGF or less clustered VEGF. Last, sustained released VEGF from nV resulted in sustain receptor phosphorylation and enhanced EC branching without VEGF replenishing. 

Short Bio

Professor Tatiana Segura received her Bachelors of Science degree from the University of California Berkeley and her doctorate from Northwestern University. She pursued post-doctoral training at the Swiss Federal Institute of Technology, Lausanne. Professor Segura's Laboratory studies hydrogel materials for stem cell culture and drug/gene delivery. On this topic she has published over 20 peered reviewed publications. She has been recognized with the Outstanding Young Investigator Award from the American Society of Gene and Cell Therapy, the American Heart Association National Scientist Development Grant, and the CAREER award from National Science Foundation.