In Situ Bioengineering of Arterial Vein Grafts

The autogenous saphenous vein remains the graft of choice for both coronary (500,000 annually in the US)¹ or peripheral (80,000 annually)² arterial bypass procedures. Failure of arterial vein grafts (AVGs) remains a major problem, and patients with failed grafts will die or require re-operation. Intimal hyperplasia (IH) accounts for 20% to 40% of all AVG failures³. It is believed that this adverse pathological response by AVGs is largely due to their abrupt exposure to the significantly elevated circumferential wall stress (CWS) associated with the arterial system⁴. We believe that if an AVG is given an ample opportunity to adapt and remodel to the stresses of its new environment, cellular injury may be reduced, thus limiting the initiating mechanisms of IH. The goal of this work was to develop a new mechanical conditioning paradigm, in the form of a peri-adventitially placed, biodegradable polymer wrap, to safely and functionally “arterialize” AVGs in situ. The electrospun polymer wrap was tuned so that as it degraded over a desired period of time, the mechanical support offered by it was reduced gradually, and hence the vein was exposed to slowly increasing levels of CWS in situ.