Tissue Engineered Bovine Saphenous Vein Extracellular Matrix Scaffolds Produced Via Antigen Removal Achieve High In Vivo Patency Rates

Abstract

Diseases of small diameter blood vessels encompass the largest portion of cardiovascular diseases, with over 4.2 million people undergoing autologous vascular grafting every year. However, approximately one third of patients are ineligible for autologous vascular grafting due to lack of suitable donor vasculature. Acellular extracellular matrix (ECM) scaffolds derived from xenogeneic vascular tissue have potential to serve as ideal biomaterials for production of an off-the-shelf vascular graft capable of eliminating the need for autologous vessel harvest. Using the antigen removal tissue processing method an off-the-shelf small diameter (< 3 mm) vascular graft from bovine saphenous vein was produced with significantly reduced antigenic content, while retaining the structure and function of its native vascular ECM proteins. Elimination of native tissue antigen content conferred graft-specific adaptive immune avoidance. Retention of native ECM protein macromolecular structure, as assessed by collagen polarization, resulted in pro-regenerative cellular infiltration, ECM turnover and innate immune self-recognition. Finally, retention of the delicate vascular basement membrane protein integrity conferred endothelial cell repopulation and 100% patency rate in a rabbit jugular interposition model, comparable only to Autograft implants. Alternatively, the lack of these important basement membrane proteins in otherwise identical scaffolds yielded a patency rate of only 20%. We conclude that acellular antigen removed bovine saphenous vein ECM scaffolds have potential to serve as ideal off-the-shelf small diameter vascular scaffolds with high in vivo patency rates due to their low antigen content, retained native tissue basement membrane integrity and preserved native ECM structure, composition and functional properties.