Development of small caliber vascular graft with stabulizing blood-material interface with monolayr absorbed protein layr.

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Although many synthetic vascular grafts have been developed and evaluated experimentally or clinically, none of them have met long-term patency when applied as small diameter vascular substitution. We have developed a small caliber vascular graft (3 mm id.) using 2-hydroxyethylmetacrylate (HEMA) and Stirene (St) block copolymer coating. HEMA-St block copolymer formed micro-domain structure and demonstrated improved blood compatibility in both in vitro and in vivo experiments. The graft consists of three layred structure : Dacron for the outer layr, polyurethane in middle layr, and a HEMA-St block copolymer coating for the inner layr. The grafts were evaluated in dogs bilateral carotid replacement model. All grafts were patent without detachable thrombi along the graft length including anastomotic sites. Scanning electron micrographs of retrieved graft lumen showed fairly clean surfaces covered with a homogeneous protein-like layr without microthrombi or endotherial ell lining.The thickness of the surface protein layr measured by a transmission electron microscopy was about 200A which can be described as monolayr protein absorption regardless of implantation period of as much as one year. A stable monolayr absorbed protein layr formed on HEMA-St block copolymer surfaces demonstrated nonthorombogenic activities in vivo and secure long-term patency of small caliber vascular grafts with the absence of an endotherial cell lining.