PERFORMANCE OF SMALL-DIAMETER SYNTHETIC VASCULAR PROSTHESES WITH CONFLUENT AUTOLOGOUS ENDOTHELIAL-CELL LININGS

Autologous grafts are superior to their synthetic counterparts for gra fting arteries smaller than 6-mm diameter both in terms of acute throm bogenicity and chronic intimal hyperplasia. Endothelial cell (EC) coat ing of the blood contacting surface may reduce thrombogenicity of synt hetic small diameter vascular prostheses. In this study, the survival of EC monolayers on synthetic 4-mm diameter arterial prostheses over s hort-term implantations (less than or equal to 6 weeks) was examined. Graft types examined were expanded polytetrafluoroethylene (ePTFE) and microporous polyurethane (PU). Lumenal coverage with ECs was achieved by culturing ovine ECs on prostheses treated by either physical adsor ption or covalent binding of ovine fibronectin (Fn). An ovine carotid interposition model was used to examine the performance of EC coated e PTFE and microporous PU over implantation periods of 1, 3, and 6 weeks . Outcomes assessed at the end of each experiment were graft patency, area covered by ECs, and thrombus free surface area (TFSA). Fn concent ration, cell density at the time of coating and prostacyclin productio n in vitro were similar for both graft types. Occlusion occurred more frequently in unseeded grafts compared with EC coated grafts over 3 an d 6 week implantation periods; however, the difference was not signifi cant (p = 0.099). In prostheses precoated with ECs, approximately 40-6 0% of the surface area remained covered with endothelial-like cells fo llowing the first postoperative week. Recovery of EC layers occurred r apidly thereafter with 80-90% coverage at 3 weeks. TFSA remained low i n comparison to EC cover in these prostheses until between 3 and 6 wee ks postoperatively, suggesting a lag phase in recovery of EC function of seeded cells. In contrast, EC cover of unseeded prostheses only ach ieved 10-30% at 3 weeks, primarily by pannus EC ingrowth from the adja cent artery. TFSA of unseeded grafts increased in direct proportion to EC cover over time suggesting that there was no lag phase in function of these ingrow ing cells. (C) 1996 John Wiley & Sons, Inc.