The control of endothelial cell adhesion and migration by shear stress and matrix-substrate anchorage

Endothelial cells constitute the natural inner lining of blood vessels and possess anti-thrombogenic properties. This characteristic is frequently used by seeding endothelial cells on vascular prostheses. As the type of anchorage of adhesion ligands to materials surfaces is known to determine the mechanical balance of adherent cells, we investigated herein the behaviour of endothelial cells under physiological shear stress conditions. The adhesion ligand fibronectin was anchored to polymer surfaces of four physicochemical characteristics exhibiting covalent and non-covalent attachment as well as high and low hydrophobicity. The in situ analysis combined with cell tracking of shear stress-induced effects on cultured isolated cells and monolayers under venous (0.5 dyn/cm²) and arterial (12 dyn/cm²) shear stress over a time period of 24 h revealed distinct differences in their morphological and migratory features. Most pronounced, unidirectional and bimodal migration patterns of endothelial cells in or against flow direction were found in dependence on the type of substrate-matrix anchorage. Combined by an immunofluorescent analysis of the actin cytoskeleton, cell-cell junctions, cell-matrix adhesions, and matrix reorganization these results revealed a distinct balance of laminar shear stress, cell-cell contacts and substrate-matrix anchorage in affecting endothelial cell fate under flow conditions. This analysis underlines the importance of materials surface parameters as well as primary and secondary adhesion ligand anchorage in the context of artificial blood vessels for future therapeutic devices.