Morphological study of small-caliber hybrid vascular grafts upon replacement of canine common carotid arteries

Abstract

Objective To investigate the in vivo morphological change of hybrid vascular graft made of porcine fibrin and microprocessed SPU film under the hemodynamic condition for predetermined period of time. Methods Autologous vascular endothelial cells derived from the saphenous veins of 6 adult mongrel dogs were cultured and proliferated in vitro in M199 culture medium, prelined on the luminal surface of lyophilized porcine fibrin tube wrapped with a SPU thin film with multiple micropores as a compliant scaffold. After canine common carotid arteries were bilaterally replaced with these vascular grafts for 4 weeks, light and electron microscopy, radiological imaging examination and immunohistochemistry were performed to evaluate the patency and remodeling in vivo. Results Eight of 10 engineered vascular grafts were patent ( patency rate 80% ). The patent grafts possessed thin, smooth and glistening luminal surfaces at the predetermined observation period up to 4 weeks. The intimal layer was covered with confluent, cobblestone-like monolayered cells that were positively stained with factor Ⅷ-related antigen. The thickness of the neoarterial walls was about 900 μm at 4th week after implantation. Vascular medial tissue rich in smooth muscle cells in the hierarchic structures of arterial wall was observed, and more interestingly, mass of elastic fiber was found in the medial tissue as early as 4 weeks postoperatively. Conclusion The endothelialized hybrid vascular grafts can be transformed to similar hierarchic structures of arterial walls under the hemodynamic condition for as early as 4 weeks. Key words: Tissue engineering; Blood vessel; Fibrin; Transplantation