Effect of glow discharge surface modification of plasma TFE vascular graft material on fibronectin and laminin retention and endothelial cell adhesion

The effects of glow discharge surface modification of plasma TFE vascular graft material (plasma TFE, Atrium Medical Corp., Hollis, NH) on the binding and retention of fibronectin and laminin as well as endothelial adherence were examined. The binding of both fibronectin and laminin to plasma TFE increased as a function of protein concentration in the range of 0.02 to 200 μg/ml. Binding to plasma TFE was not saturable in this range of protein concentrations. Fibronectin and laminin binding to plasma TFE was time-dependent, reaching a maximal level (1.8 and 3.2 μg/cm² of bound fibronectin and laminin, respectively) after 30 min (fibronectin) and 4 hr (laminin). Binding was not the result of an accumulation of unbound protein in graft interstices since graft prewetting did not alter the amount of either fibronectin or laminin associated with plasma TFE. In addition, binding was not the result of protein modification during radiolabeling, since unlabeled fibronectin and laminin could compete effectively with their iodinated counterparts for binding to plasma TFE. Dissociation of bound fibronectin and laminin from plasma TFE was rapid, and less than 12% remained bound 60 min after washing. Plasma TFE subjected to glow discharge in O₂ and carrying negatively charged functional groups on graft surfaces, exhibited a fivefold increase in fibronectin and laminin binding. In addition, more than 85% of the bound fibronectin and laminin was retained 24 hr after washing. The enhanced retention of fibronectin or laminin by these grafts was associated with an increase in endothelial cell adhesion. Endothelial cell adhesion to fibronectin-coated, negatively charged plasma TFE was significantly greater than to fibronectin-coated unmodified plasma TFE (P < 0.05, Student's t test). In contrast, the binding and retention of fibronectin and laminin by plasma TFE subjected to glow discharge in NH₃ and carrying positively charged functional groups on graft surfaces was not enhanced and endothelial cell adhesion to this graft material was not significantly greater than cell adhesion to unmodified plasma TFE. These findings suggest that a combination of specific surface modification (i.e., glow discharge in O₂) and protein precoating (i.e., fibronectin) may enhance the efficiency of autologous endothelial cell seeding of these prosthetic grafts.