Detachment of Human Endothelial Cells Under Flow From Wettability Gradient Surfaces with Different Functional Groups

In this study, the position bound adhesion, spreading and detachment under flow of human umbilical cord endothelial cells (HUVEC) was studied on a dichlorodimethylsilane (DDS), dimethylocta-decylchlorosilane (DOCS) and tridecafluor-1,1,2,2-tetrahydrooctyl-1-dimethylchlorosilane (TFCS) wettability gradient on glass. Gradient surfaces were prepared by the diffusion method and characterized by the Wilhelmy plate technique for their wettability and by X-ray photoelectron spectroscopy (XPS) for their chemical composition. Quantitative analysis of the cellular response on the wettability gradient surfaces showed that the position bound cellular response was influenced by wettability for each type of gradient in a different way. On DDS-wettability gradients, cells withstood flow best on hydrophilic regions of the gradient with advancing water contact angles below 25 degrees while on TFCS-wettability gradients this inversal point was located on regions of the gradient with advancing water contact angles around 65 degrees. After the onset of flow, cells detached from the DOCS surface, but remained adhering in low numbers irrespective of the position bound wettability. This paper confirms that cells have unfavourable interactions with hydrophobic, immobile surfaces, like adsorbed DDS on glass. However, if the hydrophobicity is created by more mobile, relatively long chain groups, possibly yielding incomplete surface coverage due to their mobility, favourable interactions may also occur on more hydrophobic surfaces