Kinetics of endothelial cell-surface attachment forces.

Physical and biochemical forces exist that are necessary for the persistent attachment and function of ECs on native and prosthetic blood vessels. The optimization of conditions that permit regeneration of these attachment forces may allow rapid establishment of a durable, biocompatible EC monolayer. We examined the effects of three major factors, protein substrate, EC incubation time, and shear stress, on the attachment kinetics of human adult ECs to two different polymers. ECs were incubated up to 30 minutes on polymers (PS or PET) coated with extracellular matrix proteins: collagen I/III, fibronectin, collagen IV/V, laminin, gelatin, or saline control. After incubation, continued attachment in the presence of shear stress (created in a rotating disc device) between zero and 90 dynes/cm2 for 30 minutes was evaluated. Maximal adherence was observed on all substrates by 30 minutes. Therefore, after a 30-minute incubation, the percentage of cells attached (postshear ECs/preshear ECs/preshear ECs X 100) was measured as a function of shear stress. ECs attached to a matrix of fibronectin or collagen I/III demonstrated shear-resistant adherence after as little as 5 minutes of static incubation before initial shear exposure. By 30 minutes, more than 90% of the ECs on both matrices demonstrated the ability to remain attached in the presence of 90 dynes/cm2 of shear stress. We conclude that forces that attach ECs to surfaces are affected by temporal factors (incubation time) and substrate composition and may be quantified with a defined shear stress detachment assay. Understanding and manipulating these temporal physiochemical parameters should allow one to re-create an optimal EC monolayer on a blood-contacting surface.