FIBRONECTIN AND AVIDIN-BIOTIN AS A HETEROGENEOUS LIGAND SYSTEM FOR ENHANCED ENDOTHELIAL-CELL ADHESION

A preadsorbed layer of ''heterogeneous'' integrin-dependent and -indep endent protein was used to enhance initial integrin-mediated endotheli al cell attachment and spreading. Glass substrates were treated with f ibronectin (Fn) and avidin coupled through adsorbed biotinylated bovin e serum albumin (b-BSA). The slides then were seeded with biotinylated BAEC. Control ''homogeneous'' surfaces were slides adsorbed with eith er Fn or avidin coupled to b-BSA. The cells were incubated for 0.5 h i n serum containing media and exposed to a range of shear stresses in a laminar flow variable-height flow chamber. The critical shear stress to detach 50% of the seeded cells on the heterogeneous ligand surface was significantly greater than for either of the control homogeneous l igand systems (p < 0.001). Cellular spreading during the initial perio d of 0-2 h also was higher (p < 0.05) on the heterogeneous ligand-trea ted surface than on the surface of either of the homogeneous controls. The close contact area of the cell membrane with the substrate 1 h af ter seeding in serum-containing media was measured using TIRFM. Cells attached onto the heterogeneous ligand-treated surfaces had a signific antly (p < 0.01) higher area of close contact with the substrate, whic h is consistent with a greater degree of attachment and spreading. The results indicate that the combination of integrin-dependent and -inde pendent adhesion systems using heterogeneous ligands further enhances initial endothelial cell attachment and spreading. (C) 1998 John Wiley & Sons, Inc.