Long term survival of synthetic vascular graphs is often diminished by thrombosis and intimal hyperplasia. One approach to increase patency is to coat the lumenal surface of prosthetic grafts with endothelial cells; these endothelialized grafts have improved patency rates and less intimal hyperplasia. One limitation of this approach is the poor retention of the endothelial cells on the grafts, a problem recently overcome in Dr. Ballermann's laboratory y exposing cells seeded on grafts to shear stress, applied stepwise, in vitro. Since endothelial cells are capable of serving as a target for gene therapy, it is likely that patency of endothelial-lined grafts can be further improved by lining them with genetically modified endothelial cells that synthesize and secrete agents locally to control thrombosis and intimal hyperplasia. This project proposes to stably transfect endothelial cells with constructs of nitric oxide synthetase or a secreted form of fibroblast growth factor receptor. Grafts lined with these cells should be less subject to thrombosis and PDGF- or FGF-driven intimal hyperplasia. The cells will be seeded inside PTFE grafts, conditioned with in vitro shear stress to improve cell retention, and then implanted into rat aortas. As appropriate, the endothelial cell retention rate, graft patency rate and graft history will be examined as a function of time. The proposed studies constitute a step towards producing artificial blood vessels for local gene therapy in humans.
