Canine endothelial progenitor cell-lined hybrid vascular graft with nonthrombogenic potential

Abstract

Objective We sought to fabricate a compliant engineered vascular graft (inner diameter of approximately 4.5 mm and length of 6 cm) lined with endothelial progenitor cells derived from circulating peripheral canine blood and to verify its nonthrombogenicity potential in vivo. Methods Autologous circulating endothelial progenitor cells derived from the peripheral veins of 6 adult mongrel dogs were isolated by using a density gradient method. The cells were proliferated in vitro in EGM-2 culture medium, prelined on the luminal surface of in situ–formed collagen type I meshes as an extracellular matrix, and wrapped with a segmented polyurethane thin film with multiple micropores as a compliant scaffold. After canine carotid arteries were bilaterally implanted with these grafts for 1 and 3 months, microscopic observation, histologic staining, and immunochemical staining were performed to evaluate morphogenesis. Results After 33.3 ± 10.5 days of culture in vitro, 4.2 ± 1.2 × 10 6 endothelial progenitor cells were obtained. Eleven of the 12 engineered vascular grafts were patent. The grafts possessed smooth, glistening, and ivory-colored luminal surfaces at the predetermined observation period up to 3 months. The intimal layer was covered with confluent, cobblestone-like monolayered cells that were positively stained with factor VIIIB–related antigen. The thickness of the neoarterial walls was approximately 300 μm at 3 months after implantation. A few smooth muscle cells were observed in the medial tissue, and fibroblasts dominated the adventitial tissue. Conclusion Circulating endothelial progenitor cells could be a substitute source of endothelial cells for endothelialization on small-diameter-vessel prostheses to ensure nonthrombogenicity.