The interaction of human endothelial cells with chemical gradient surfaces during exposure to flow

In this study, the position bound shape, spreading, detachment and migration of adhering HUVEC endothelial cells on dichlorodimethylsilane (DDS) chemical gradient surfaces was investigated during exposure to flow in a parallel plate flow chamber in the presence of serum proteins. Gradient surfaces were prepared by the diffusion method and characterized by the Wilhelmy plate technique for their wettability. In order to measure the possible influence of wettability steepness on the position bound cellular response, shallow and steep wettability gradients were prepared by applying two different diffusion times and DDS-concentrations. Quantitative analyses of the cellular response on the gradient surfaces showed that the position bound spread area and shape factor of adhering cells increased when going from the hydrophobic to the hydrophilic end, concurrent with the steepness of the gradient. After exposure to flow, cells detached immediately from the hydrophobic side and maintained their positions more easily on the hydrophilic side. Furthermore, it was shown that the position bound detachment and migration of cells depended on the steepness of the wettability gradient and the direction of the flow. When the flow was to the hydrophilic end, migration velocity did not vary along the length of the gradients, and was lower on the steep (approximately 2/xm/min) than on the shallow (approximately 3//m/min) gradients. Flowever, when flow was to the hydrophobic end, migration velocities appeared position bound and were higher on the hydrophobic ends of both gradients.