(287d) Mimicking Selectin-Mediated Cell Motion with a Synthetic Receptor System

Kalasin, S., University of Massachusetts
Davis, J., University of Massachusetts, Amherst
Duffadar, R. D., University of Massachusetts

The rolling of neutrophils over the injury-stimulated endothelium of blood vessels results from the coupling of selectin ? sialyl Lewisx bonding and disbonding kinetics to hydrodynamic forces on the far surface of the cell. Much is known about this system, from studies with neutrophils themselves or from studies employing particles and surfaces functionalized with the relevant biomolecules. This contribution explores how an artificial receptor can be designed so that biomimetic particles exhibit similar dynamic motion signatures to neutrophils. We compare the firm adhesion, rolling, and non-adhesive behaviors of neutrophil rolling to a system that relies largely on electrostatic attractions, focusing on the state space diagrams of the Hammer and Schwarz groups. With the artificial receptor we experimentally access regions of parameter space not easily studies with selectins, including systematic variations in the density of the receptor, its distance from the underlying substrate, and the range of repulsion provided by the background surface or passivating layer. These variables are found to be as important as those more typically studied in cell-based and cell-free systems.