The growth, spreading, and shape of human skin fibroblasts (PK 84) and human umbilical cord endothelial cells on dichlorodimethylsilane (DDS) and dimethyloctadecylchlorosilane (DOGS) gradient surfaces were investigated in the presence of serum proteins. Gradient surfaces were prepared on glass using the diffusion technique. Fibroblasts grew well on the hydrophobic and hydrophilic sides of both types of gradient surfaces, but endothelial cells were far more sensitive to changes in wettability. Endothelial cell growth was fully inhibited on the hydrophobic side of the DDS gradient surface, but not on the hydrophobic side of the DOGS gradient surface. In contrast, spreading of both fibroblasts and endothelial cells during growth was approximately uniform over the length of DDS and DOGS gradient surfaces. By comparison with studies involving only adhesion and spreading of cells in the absence of growth, it is suggested that exchange interactions between adsorbed serum proteins and endogeneous adhesive proteins are responsible for cell spreading during growth on the hydrophobic sides of the gradient surfaces. Furthermore, endothelial cells may be able to find hydrophilic footholds through adsorbed DOGS layers needed for their growth, that may occur less on more confluently adsorbed DDS layers. (C) 1997 Academic Press.