Production of endothelium-derived factors from sodded expanded polytetrafluoroethylene grafts

Purpose: Experiments were designed to determine whether endothelium isolated from adipose tissue and sodded onto expanded polytetrafluoroethylene grafts release endothelium-derived vasoactive factors. Methods: Thin-walled expanded polytetrafluoroethylene grafts (6 mm internal diameter, 6 cm length, 30 μm pore size), one sodded with autogenous endothelial cells, the other unsodded, were implanted bilaterally in carotid arteries of 30 male mongrel dogs. Dogs were treated with 325 mg aspirin daily. After 6 weeks grafts were excised and perfused in a bioassay system. Effluent from the grafts stimulated with either acetylcholine, thrombin, adenosine 5-diphosphate, or the calcium ionophore A23187 was superfused over rings of canine femoral arteries without endothelium contracted with phenylephrine. Effluent from the grafts was analyzed by radioimmunoassay for thromboxane B₂, 6- ketoprostaglandin F(1α), endothelin-1, and C-type natriuretic peptide. Results: Ninety percent of the sodded grafts and 87% of the unsodded grafts were patent after 6 weeks. Bioassay rings superfused with effluent from sodded grafts stimulated with acetylcholine relaxed significantly more than rings superfused with effluent from similarly stimulated unsodded grafts. Biochemical analysis of the effluent showed an increase in 6-keto prostaglandin F(1α) and C-type natriuretic peptide and a decrease in endothelin-1 and thromboxane B₂ release from the sodded compared with the unsodded grafts. Scanning electron microscopy showed a continuous layer of endothelial cells lining only the sodded grafts. Staining for α-actin and heavy-chain myosin showed a differentiated layer of smooth muscle below the endothelial layer on the sodded grafts. Finally, there was positive staining for C type natriuretic peptide and endothelin-1 in the endothelium of the sodded grafts. Conclusions: These results indicate that endothelial cells of sodded expanded polytetrafluoroethylene grafts produce endothelium-derived vasoactive factors. In addition, receptor-coupled synthesis/release of these factors is retained in sodded endothelial cells.