Nobutaka Tani

An in vitro endothelialized compliant vascular graft minimizes anastomotic hyperplasia.

The authors developed a hybrid vascular graft consisting of three components: a polyurethane (PU) graft (internal diameter = 3 mm; length: 5 cm) with a compliance similar to that of natural arteries; an artificial basement membrane composed of a complex gel of Type I collagen and dermatan sulfate; and an autogenous endothelial cell (EC) monolayer constructed before implantation. As a continuation of their previous study that focused on antithrombogenicity for as long as 1 month after implantation, the authors evaluated the antihyperplastic characteristics of their hybrid vascular graft for longer implantation periods. The hybrid grafts were implanted bilaterally into carotid arteries of dogs without anticoagulant or anti-platelet agents. The implantation period ranged from 6 to 26 weeks. The overall patency rate observed in this study was 70%. Histologic evaluation of grafts revealed that luminal surfaces of the arteries and grafts joined uniformly and smoothly. The mean initimal thickness of grafts was approximately 80 microns at 12 weeks; there was no statistically significant difference in the thickness between portions of the graft. Little additional increase was observed at 26 weeks. The intimal thickness of adjacent arteries was small. Thus, anastomotic hyperplasia was considered minimized. These encouraging results were explained in terms of synergistic activities of the compliant PU graft and durable EC monolayer as follows. The PU graft, which was fabricated to have the same compliance as that of natural arteries, minimized the compliance mismatch at the anastomoses.(ABSTRACT TRUNCATED AT 250 WORDS)

Improved patency of an elastomeric vascular graft by hybridization.

A newly devised hybrid graft with high antithrombogenicity for small caliber vascular grafts was developed. The design concept was based on the incorporation of a compliant open cell structured graft, autogenous endothelial cells (ECs), and artificial basement membrane. The latter, a gel complex of type I collagen and dermatan sulfate that showed enhanced adhesion and growth of ECs but reduced platelet adhesion, was coated onto a microporous polyurethane graft (internal diameter, 3 mm; length, 4.5 cm), with near-natural compliance. Ten seeded grafts were implanted bilaterally into the carotid arteries of dogs; anticoagulant or antiplatelet therapy was not administered. This hybrid graft showed a marked improvement in patency at 1 month compared with that of simply preclotted grafts (control specimens). This result was explained by the almost complete endothelialization when the graft was implanted, a high degree of adherent strength resistance to shear stress, and a high proliferative potential. Thus, this approach of combining biomechanical and cellular engineering designs may lead to an important functional small caliber graft.