Vascular cell attachment and procoagulant activity on metal alloys

Abstract

The attachment and growth of vascular smooth muscle cells on biomaterials used as components of devices implanted in the vascular space may influence the biocompatibility of such materials. The nature of the materials may affect the attachment and/or the activation of these cells' procoagulant responses. Therefore, the main objective of this study was to measure the strength of adhesion of these vascular cells to potential biomaterials (titanium, zirconium alloys, and stainless steel) by exposing them to a range of shear stresses (50-300 dyn cm-2) in a parallel plate flow chamber. The procoagulant responses of the cells were evaluated by measuring the tissue factor (TF) activity promoted by the different materials under flow conditions. The materials supported distinctly different levels of initial cell adhesion in static culture. However, the fraction of adherent cells did not decline significantly with incrementally increasing shear stress within the range tested. TF expression, as measured by factor Xa (FXa) production, was material-dependent. For example, cells cultured on Ti1313 exhibited more FXa production (13.2 nM 10-5 cells) than Ti1313(DH) (8.5 nM 10-5 cells) or stainless steel (2 nM 10-5 cells). Thus, our studies indicate that the level of adhesion, strength of attachment and the expression of procoagulant activity of adherent vascular cells depend strongly on the nature of the underlying biomaterial.