Decellularized Human Umbilical Artery Exhibits Adequate Endothelialization in Xenogenic Transplantation

Decellularized human umbilical arteries (dHUA) is an off-the-shelf graft that can potentially serve as vascular scaffolds in tissue engineering of small-diameter vascular grafts. This research aimed to investigate that dHUA could exhibit adequate endothelialization for a long term in xenogenic transplantation. 13 dHUAs were implanted in rat abdominal aortas up to 90 days. Rats were divided into three groups in terms of survival period: Group 1, one to seven days (n = 6); Group 2, 14 to 30 days (n = 4) and Group 3, 90 days (n = 3). The explants were analyzed by histological, immunohistochemistry and magnetic resonance angiography (MRA) examination. Allograft implantation of 12 decellularized rat abdominal aortas’ were processed the same way as the rat in order to make a comparison for survival rates (Group 1, n = 5; Group 2, n = 4; Group 3, n = 3). The results demonstrated that the survival rates of xenograft and allograft implantation were estimated to be 59.2% vs. 58.3% in Group 1, 50.7% vs. 58.3% in Group 2 and 3. Grafts harvested from Group 2 were showed CD31, endothelial nitric oxide synthase expression at intima, and α-smooth muscle actin, CD45, CD68 and CD168 expression at the tunica externa. A layer structure with obvious endothelialization and fiber regeneration/orientation could be inspected from the explants of Group 3. MRA demonstrated the patency of dHUA on day 30 and 90. In conclusion, more than 50% dHUA maintained patency in the xenogenic model till 90 days after surgery. A mature vessel-like functional structure with intact endothelial layer was observed then. This warrants further study in the reinforcement of decellularized vascular scaffolds.