Abstract
The hierarchically structured hybrid vascular graft, resembling to the layered structure of the intima and the media of a natural vessel, was considered to provide the structural stability and antithrombogenicity especially at an acute phase. Two types of hybrid vascular grafts were constructed on knitted Dacron grafts (ID=4mm, Length; 6cm) in vitro. One consisted of endothelial cell monolayer and smooth muscle cell multilayers (MODEL II), the other consisted of only endothelial cell monolayer (MODEL I). Designed artificial basement membrane and extracellular matrix were a mixed gel of type I collagen and dermatan sulfate. Both types of grafts were implanted in nine dogs for up to 12 weeks. All grafts were patent. At 2 weeks post implantation, MODEL II-grafts showed the oriented intima completely covered with endothelial cells, and compactly reorganized media composed of multilayered smooth muscle cells, while MODEL I-grafts showed non-oriented endothelial cell monolayer and few smooth muscle cells beneath the endothelium. Observation up to 12 weeks showed the tendency for the thickness of media to increase time-dependently. At 2 weeks post implantation, more complete endothelial coverage was observed in MODEL II-grafts than MODEL I-grafts (100%vs 92%). It can be said that in vitro constructed smooth muscle cell layer contributes to the stabilization of endothelial layer at an acute phase.
