Arterial Replacement with Compliant Hierarchic Hybrid Vascular Graft: Biomechanical Adaptation and Failure

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Abstract
Two types of hybrid vascular grafts were hierarchically structured with an autologous smooth muscle cell (SMC)–inoculated collagen gel layer and an endothelial cell (EC) monolayer, and wrapped with different elasomeric scaffolds. Type A graft was wrapped with poly(urethane)-nylon mesh, and type B graft was wrapped with an excimer laser-directed microporous segmented polyurethane (SPU) film as the scaffold. Type A graft was more compliant than canine carotid arteries, whereas compliance of type B graft was close to that of native arteries. After implantation into canine carotid arteries for 1 month, all type A grafts were dilated due to loosening of the mesh, resulting in loss of prelined ECs and thrombus formation. In contrast, type B grafts developed a well-organized neoarterial wall composed of a confluent EC monolayer and SMC-resided medial tissue, resulting in only slightly appreciable thrombus and minimal tissue ingrowth 6 months after implantation. Compliance of type B graft was reduced at 6 month's implantation, which is mostly due to encapsulated connective tissue formed around the graft.