(601al) Divergence of Instantaneous Versus Long Time- and Length-Scale Adhesion Dynamics of Cells with Selectins in Fluid Flow

Cell adhesion to selectins admist the myriad of mechanical forces resulting from fluid flow during transit in the circulatory system critically regulates cellular trafficking involved in a variety of physiological and pathophysiological processes. To date, the instantaneous adhesion behavior of cells to selectins or single molecule biophysics of selectin/ligand interactions have been well described. However, the time-averaged adhesive behavior of cells to selectins in physiological flow conditions, that contributes most significantly to the likelihood of cell infiltration into distant tissues from the vascular system, has been largely overlooked. Herein we report the design and implementation of a so-called “cell adhesion chromatography” platform that enables the independent analysis of instantaneous versus long time- and length-scale adhesion behavior in order to probe how likely cells in prolonged contact with adhesive substrates under shear fluid flow are to sustain contact with selectins and thereby escape from the vasculature. A parallel plate flow chamber was designed to provide uniform contact of cells in a pulse input with the planar substrate functionalized with purified selectins. Borrowing from classical chromatography theory, residence time within the chamber is used as a proxy for overall time-averaged cell adhesivity for the substrate and can be juxtaposed with the instantaneous interaction behavior measured via videomicroscopy to yield a metric of adhesion persistence. By implementing this novel methodology, we find that a bimodal dependency of adhesion persistence with rolling velocity exists for cell adhesion to L- but not P- or E-selectin. Furthermore, this technique allows us to quantify for the first time the relative adhesion efficiencies and persistence of malignant versus healthy cells. To our knowledge, this is the first report detailing how long time- and length- scale cell adhesion behavior is distinct from instantaneous cell binding activity in a selectin- and shear stress-dependent manner.