Construction of small-caliber vessels by autogenous connective tissue: an experimental study in rats

Objective To observe the structural changes of autogenous connective tissue tubes when used as substitute of blood vessels. Methods An animal model of abdominal aorta grafting was created in Wistar rats. A silicon rod of 2 mm in diameter and 15 mm in length was embedded in the muscular layer of the abdominal wall. After 6 weeks the connective tissue tube formed around the silicon rod was harvested and used as vessel substitute to bridge the defect of the abdominal aorta. 48 rats were randomly divided into 4 groups, with 12 each. In the control group, 1 cm segment of abdominal aorta was cut and orthotopically grafted. In the experimental groups, defect of abdomial aorta was bridged by the autogenous connective tissue tube. Measurement of patency of the grafts, light microscopic, scanning and transmitting electron microscopic observation for structural changes of the grafts were carried out before grafting and 2, 4 and 6 months after grafting. Results The vessels were found to be patency in all groups. In vascular substitutes of 2 months group, structures of an artery including endothelial cells and smooth muscle cells were present in most part of the intima and media of the vascular wall. Continuous lining of the vascular wall was seen in vascular substitutes of 4 months group. The structures of vascular substitutes of 6 months group were similar to those of the control group. Formation of elastic band was seen in the wall near the anastomosis site. Conclusion Autogenous connective tissue tubes keep good pantency 6 months after being used as vascular substitutes for grafting. By that time the thickness and structures of the graft were similar to those of normal vessels.