Pyrolytic Carbon Coating Enhances Teflon and Dacron Fabric Compatibility with Endothelial cell Growth

Abstract

Compatibility with endothelial cell attachment and growth appears to be an important requisite of vascular prosthetic materials, possibly influencing thrombosis, pseu-dointimal hyperplasia, and accelerated atherosclerosis at the site of blood-material interaction. Since deposition of pyrolytic carbon (PC) on prosthetic surfaces has been associated with enhanced hemocompatibility, in the present study we assessed whether a thin layer (0.5 μm) of PC deposited onto materials such as knitted Teflon® and Dacron® enhanced endothelial cell attachment and growth. Cultured human umbilical vein endothelial cells (HUVEC) were seeded at a density of 4.5 x 10⁴ cells/cm² on PC-coated and uncoated grafts. In order to quantify endothelial cell attachment on the fabrics, the area of Teflon and Dacron fabrics covered by endothelial cells was estimated on day 2 after seeding using the point counting method in scanning electron micrographs. Subsequently, on days 2 and 4 after seeding, endothelial cell proliferation was measured both as number of endothelial cells and as total proteins of the endothelial cells covering the fabrics. On day 2 endothelial cell growth on PC-coated fabrics was greater (mean ± SE; area 42.3 ± 9.9 mm², n = 6; cell number 3.9 x 10⁴ ± 3.03 x 10³ cells, n = 4; total proteins 14.9 ± 1.2 μg, n = 4) than on uncoated fabrics (area 10.6 ± 4.6 mm², n = 6; cell number 2.9 x 10⁴ ± 4.3 x 10³ cells, n = 4; total proteins 11.3 ± 1.7 μg, n = 4; P < 0.001, < 0.05 and < 0.05, respectively). On day 4 (n = 6) endothelial cells showed marked proliferation and both cell number and total proteins were still significantly higher on PC-coated fabrics (mean ± SE: cell number 1.9 x 10⁶ ± 1.5 x 10⁵ cells, total proteins 754 ± 57 μg) than on the uncoated ones (cell number 1.4 x 10⁶ ± 5.9 x 10⁴ cells; total proteins 567 ± 23 μg, P < 0.05 for both comparisons). LDH activity (a measure of cytotoxicity) and prostacyclin (PGI₂) production (a measure of activation of arachidonic acid metabolism, in the culture medium were both less (P < 0.01) in the presence of PC-coating than in its absence.

We conclude that a thin PC film on Teflon and Dacron knitted fabrics enhances in vitro endothelial cell attachment and growth and reduces LDH leakage and activation of arachidonic acid metabolism in endothelial cells.