Rapid endothelialization of PhotoFix natural biomaterial vascular grafts

To date, no off-the-shelf graft has performed better than the autologous vessel in applications requiring small-bore (< 6-mm diameter) vascular grafts. Much research has been devoted to seeding endothelial cells on synthetic grafts to improve their long-term clinical performance. One key challenge is the ability to retain the endothelium on the graft lumen for extended times. The goal of this research was to develop a process to seed endothelial cells inside a vascular graft and to quickly condition the cells so as to minimize their damage or removal under physiological flow. In addition, the use of PhotoFix(R) natural biomaterial grafts as an improved substrate for human umbilical vein endothelial cells has been evaluated. A motorized system that provides uniform cell seeding of a small-diameter graft (4-mm inner diameter, 10-cm length) by automated radial rotation has been developed. The same system is subsequently adapted for gradual increases in flow rates to strengthen the endothelium, which ultimately was exposed to a final flow rate of 300 ml/min. This process is accomplished without graft transfer, decreasing risks of contamination and physical damage. Cell coverage and cell morphology were evaluated with the use of fluorescence microscopy and scanning-electron microscopy to determine the effectiveness of the flow conditioning process. It was found that endothelial cells exhibit roughly 20-50% improved adhesion to PhotoFix vessels compared to fibrin-treated polytetrafluoroethylene (PTFE) synthetic grafts. Flow conditioning for 6 h enhanced in vitro cell retention by 24% and 40% on PhotoFix and PTFE grafts, respectively.