Peritoneal pre-conditioning impacts long-term vascular graft patency and remodeling

There are questions about how well small-animal models for tissue-engineered vascular grafts (TEVGs) translate to clinical patients. Most TEVG studies used grafting times & LE;6 months where conduits from generally biocompatible materials like poly(& epsilon;-caprolactone) (PCL) perform well. However, longer grafting times can result in significant intimal hyperplasia and calcification. This study tests the hypothesis that differences in proinflammatory response from pure PCL conduits will be consequential after long-term grafting. It also tests the long-term benefits of a peritoneal pre-implantation strategy on rodent outcomes. Electrospun conduits with and without peritoneal pre-implantation, and with 0 % and 10 % (w/w) collagen/PCL, were grafted into abdominal aortae of rats for 10 months. This study found that viability of control grafts without pre-implantation was reduced unlike prior studies with shorter grafting times, confirming the relevance of this model. Importantly, pre-implanted grafts had a 100 % patency rate. Further, pre-implantation reduced intimal hyperplasia within the graft. Differences in response between pure PCL and collagen/PCL conduits were observed (e.g., fewer CD80+ and CD3+ cells for collagen/PCL), but only pre-implantation had an effect on the overall graft viability. This study demonstrates how long-term grafting in rodent models can better evaluate viability of different TEVGs, and the benefits of the peritoneal pre-implantation step.