Static and Dynamic Assays of Cell Adhesion Relevant to the Vasculature

Methods are described for analyzing adhesion of isolated cells (such as leukocytes, tumor cells, or precursor cells) to purified adhesion receptors or cultured endothelial cells. "Static" assays (where cells are allowed to settle on the adhesive substrates) and flow-based assays (where cells are perfused over the substrates) are compared. Direct observations of the time course of adhesion and migration can be made when purified proteins or endothelial cells are cultured in plates, after cells are allowed to settle onto them for a desired period. In the flow-based assay, cells are perfused through coated glass capillaries, flow-channels incorporating coated plates, or commercially available preformed channels. Again, direct video-microscopic observations are made. In this assay various stages of capture, immobilization, and migration can be followed. In general, the static systems have higher throughput and greatest ease of use, but yield less detailed information, while the flow-based assay is most difficult to set up but is most physiologically relevant if one is interested in the dynamics of adhesion in the vasculature.