MICROFIBRILLAR ELASTIC POLYMER WRAPPING OF RAT VENA CAVA FOR THE STUDY OF ENGINEERED ARTERIAL VEIN GRAFTS

摘要

The autologous saphenous vein graft remains the graft of choice for 95% of surgeons performing coronary artery or peripheral bypass procedures. Within the first 5 years after implantation, 20% - 40% of arterial vein grafts (AVG) fail due to intimal hyperplasia (IH)~1. This adverse pathological response by AVGs may be in part due to their abrupt exposure to the significantly elevated circumferential wall stress associated with the arterial system~2. We believe that if an AVG is given an ample opportunity to adapt and remodel to the stresses of the arterial environment, cellular injury may be reduced, thus limiting the initiating mechanisms of IH.rnAn engineered AVG, which consists of a biodegradable polymer wrap electrospun on a freshly-excised vein segment, is being developed in our laboratory. Our previous study using freshly-excised porcine internal jugular vein segments showed that the electrospining process had no deleterious effects on tissue viability, and the mid-wall circumferential wall stress (CWS) vs. time profile could be dictated through the composition and degradation of the electrospun wrap~3.rnThe objective of the current study was to scale-down this process for study using the rat - i.e., electrospinning the wrap onto a rat vena cava for ex-vivo or in-vivo (implantation into another rat) study. Rats are significantly less costly than pigs and are a more economical model to use for development of our approach. For example, the mechanical degradation rate needs to be optimized, and this may be done on a cohort of rats much more economically than in pigs. The rat vena cava is an established model for studying AVGs~4.