(535e) Vascular Endothelial Growth Factor Receptor-2 (VEGFR-2) Phosphorylation Sustained by Immobilized VEGF

The binding of vascular endothelial growth factor (VEGF) to VEGF receptor-2 (VEGFR-2) begins a signaling cascade that ultimately leads to the sprouting and formation of blood vessels. Studies conducted in vivo have found that the structure of the blood vessel network depends on the affinity of VEGF for the extracellular matrix (ECM). Soluble VEGF signaling has been linked to the formation of large, tumor-like blood vessels, while matrix bound VEGF signaling leads to smaller, capillary-like networks. However, the molecular signaling involved that result in these differences have not been thoroughly investigated. Utilizing self assembled monolayers (SAMs) on gold, surfaces were engineered that are capable of both covalent and electrostatic immobilization of VEGF. VEGF activity has been measured by its ability to stimulate human umbilical vein endothelial cell (HUVEC) proliferation and to phosphorylate VEGFR-2 in both a transfected cell line (porcine aortic endothelial cells) and endogenously producing cell line (HUVEC). Kinetic studies of the phosphorylation of VEGFR-2 by bound VEGF have revealed that VEGFR-2 phosphorylation is sustained at a constant level through 60 minutes, while phosphorylation of VEGFR-2 by soluble VEGF peaks at 5 minutes and then decreases dramatically. These kinetic curves have been fit to a chemical kinetic model that could begin to describe the mechanistic differences between soluble and bound VEGF/VEGFR-2 signaling. The concept of adjusting the affinity of growth factors to a scaffold in a biomaterial introduces another design parameter that could aide in instructing cells to form desired tissue, and developing therapies for regenerative medicine.