Development of fibrin-based tissue engineered vessels

Tissue-engineered vessels (TEV's) are being developed to supplement the short supply of available autologous vascular grafts. Biocompatibility, culture time, medium composition, culture conditions and scaffold material all influence development of a site appropriate, functional vessel with adequate mechanical strength. We developed a small-diameter TEV by mixing ovine vascular smooth muscle cells (OVSMC) into a fibrin gel that is molded around a silastic tube. The degradation rate of the fibrin gel was controlled through the addition of aprotinin in the culture medium. The molded fibrin gel was exposed to either static or pulsed condition, which applies a 5-10% distention of the inner lumen. Results show that after only 7 days of culture a reactive vessel that constricts to KCl and norepinepherine and dilates to SNAP and isoproterenol was created. The concentration of aprotinin, the time of aprotinin addition and pulsation significantly influenced the properties of engineered tissues such as weight, strength, thickness of vessel walls and contractibility to KCl, norepinephrine and U46619. These results may have important implications in tissue engineering of small diameter vessels.