Attachment, morphology and adherence of human endothelial cells to vascular prosthesis materials under the action of shear stress

In an effort to improve the long-term patency of vascular prostheses several groups now advocate seeding autologous endothelial cells (ECs) onto the lumen of the vessel prior to implantation, a procedure that involves pre-treating the prosthesis material with fibrin, collagen and/or other matrix molecules to promote cell attachment and retention. In this study, we examined the degree to which human umbilical venous endothelial cells (HUVECs) adhered to three materials commonly used polymeric vascular prosthesis that had been coated with the same commercial extra cellular matrix proteins, and after exposure to fluid shear stresses representative of femoro-distal bypass in a cone-and-plate shearing device. We quantified cell number, area of coverage and degree of cell spreading using image analysis techniques. The response of cells that adhered to the surface of each material, and following exposure to fluid shear stress, depended on surface treatment, topology and cell type. Whereas collagen coating improved primary cellular adhesion and coverage significantly, the degree of spreading depended on the underlying surface structure and on the application of the shear stress. In some cases, fewer than 30% of cells remained on the surface after only 1-h exposure to physiological levels of shear stress. The proportion of the surface that was covered by cells also decreased, despite an increase in the degree to which individual cells spread on exposure to shear stress. Moreover, the behaviour of HUVECs was distinct from that of fibroblasts, in that the human ECs were able to adapt to their environment by spreading to a much greater extent in response to shear. The quality of HUVEC attachment, as measured by extent of cell coverage and resistance to fluid shear stress, was greatest on expanded polytetrafluoroethylene samples that had been impregnated with Type I/III collagen.