Polyglactin 910/ polydioxanone bicomponent totally resorbable vascular prostheses

Abstract

Previous studies from our laboratory have shown that bioresorbable vascular prostheses woven from lactide-glycolide copolymers and implanted into arteries of several animal models become replaced by cellular tissues; the rate of replacement parallels the kinetics of prosthetic resorption. This study evaluates the efficacy of bicomponent resorbable prostheses as a method of augmenting resistance to dilatation during the resorption period of the more rapidly resorbed component. Bicomponent prostheses (n = 37) were woven from compound yarns containing 74% polyglactin 910 (PG910) and 26% polydioxanone (PDS) and were interposed into adult white New Zealand rabbit infrarenal aortas. Resultant prosthesis-tissue complexes were harvested after 2 weeks to 12 months. Specimens were photographed and sectioned for light, scanning, and transmission electron microscopy. Randomly selected fresh explants at 1 and 3 months and control aortic segments from the same rabbits were simultaneously perfused with culture media (37°C, 10080 mm Hg, 60 ml/min) and perfusates assayed by means of tritiated radioimmunoassay techniques for the stable prostacyclin metabolite 6-keto-PGF1α before and after the addition of sodium arachidonate (10 μg/ml) to the media. Results showed 100% patency, no aneurysms, and stenosis in 1 of 37 prostheses (3%). PG910 was totally resorbed by 2 months and PDS by 6 months. By 1 month inner capsule thickness was 303 ± 30 μm. In contrast to previous reports this was significantly thicker than that within 100% PDS (230 ± 40 μm) and significantly less thick than in 100% PG910 (530 ± 62 μm). Inner capsules in all three groups stabilized at similar thicknesses (417 to 502 μm). Regenerated tissues contained oriented myofibroblasts and collagen beneath endothelial-like blood-contacting surfaces. These surfaces metabolized sodium arachidonate to 6-keto-PGF1α in a similar fashion to control aortic surfaces. Although these data suggest possible clinical efficacy in multicomponent totally absorbable vascular prostheses, further work is needed to elucidate fully the mechanisms of arterial regenerative activity.