Alkylsilane-modified surfaces: Inhibition of human macrophage adhesion andforeign body giant cell formation

A homologous set of alkylsilane-modified glass surfaces with chain lengths ranging from methyl to octadecyl was prepared in order to examine the influ ence of alkyl surface chemistry on macrophage adhesion and foreign body gia nt cell (FBGC) formation. Contact angle and X-ray photoelectron spectroscop y analysis confirmed our silanation technique and indicated a consistent al kyl chain density independent of chain length. Human peripheral blood monoc ytes were isolated and cultured on these alkyl-silane surfaces for a period of 10 days. The initial density of human monocytes was similar on all surf aces. Beyond day 0 the clean glass, methyl (DM and C1), propyl (C3), and he xyl (C6) surfaces maintained a high cell density and supported macrophage d evelopment. Ln contrast, long-term macrophage density was extremely low on the tetradecyl (C14) and octadecyl (C18) surfaces. When interleukin-4 was a dded to induce FBGC formation in vitro, the DM, C1, C3, and C6 surfaces sup ported high levels of macrophage fusion while clean glass strongly inhibite d fusion. The C14 and C18 surfaces did not contain sufficient macrophages t o support FBGC formation. Cage implant studies revealed that in vivo macrop hage density and FBGC formation on clean glass and C6 surfaces was similar to in vitro data. In contrast to the monocyte culture results, the C18 cage implant samples supported significant FBGC formation, possibly as a result of different conditions within each experimental system. Radiotracer adsor ption studies of eight human serum proteins identified the high concentrati on and tenacious hold of adsorbed von Willebrand factor as being possibly i nvolved in the poor long-term macrophage density observed on C14 and C18. ( C) 1999 John Wiley & Sons, Inc.