Design and characterization of a porous pouch to prevent peritoneal adhesions during in vivo vascular graft maturation

Vein grafts for coronary artery bypass are not available in more than 30% of patients due to prior use or systemic vascular diseases. Tissue engineered vascular grafts (TEVGs) have shown promise, but intimal hyperplasia and graft thrombosis are still concerns when grafted in small-diameter arteries. In this study, we utilized the peritoneal cavity as an “in vivo” bioreactor to recruit autologous cells to electrospun conduits enclosed within porous pouches to improve the response after grafting. Specifically, we designed a new poly (ethylene glycol)-based pouch to avoid adhesion to the peritoneal wall and still allow the necessary peritoneal fluid to reach the enclosed conduit. The pouch mechanics in compression and bending were determined through experiments and finite element simulations to optimize the pouch design. This included poly (ethylene glycol) concentration, pore density, and pouch size. We demonstrated that the optimized pouch was able to withstand the estimated forces applied in the rat peritoneal cavity and it allowed maturation of the enclosed electrospun conduit. This pouch significantly reduced peritoneal adhesion formation compared to polytetrafluoroethylene pouches that have been used previously, which overcomes this potential limitation to clinical translation. After aortic grafting of pre-conditioned conduits, patent grafts with limited intimal hyperplasia were observed. Overall, this study demonstrated a new pouch design that allows the in vivo bioreactor strategy to be used for vascular tissue engineering without the potential side effect of peritoneal adhesion formation.