Platform technologies for decellularization, tunic-specific cell seeding, and in vitro conditioning of extended length, small diameter vascular grafts.

The aim of this study was to generate extended length, small diameter vascular scaffolds that could serve as potential grafts for treatment of acute ischemia. Biological tissues are considered excellent scaffolds, which exhibit adequate biological, mechanical, and handling properties; however, they tend to degenerate, dilate, and calcify after implantation. We hypothesized that chemically stabilized acellular arteries would be ideal scaffolds for development of vascular grafts for peripheral surgery applications. Based on promising historical data from our laboratory and others, we chose to decellularize bovine mammary and femoral arteries and test them as scaffolds for vascular grafting. Decellularization of such long structures required development of a novel "bioprocessing" system and a sequence of detergents and enzymes that generated completely acellular, galactose-(α1,3)-galactose (α-Gal) xenoantigen-free scaffolds with preserved collagen, elastin, and basement membrane components. Acellular arteries exhibited excellent mechanical properties, including burst pressure, suture holding strength, and elastic recoil. To reduce elastin degeneration, we treated the scaffolds with penta-galloyl glucose and then revitalized them in vitro using a tunic-specific cell approach. A novel atraumatic endothelialization protocol using an external stent was also developed for the long grafts and cell-seeded constructs were conditioned in a flow bioreactor. Both decellularization and revitalization are feasible but cell retention in vitro continues to pose challenges. These studies support further efforts toward clinical use of small diameter acellular arteries as vascular grafts.