Multi-scale simulation of L-selectin–PSGL-1-dependent homotypic leukocyte binding and rupture

V. K. Gupta, Ihab A. Sraj, Konstantinos Konstantopoulos, Charles D. Eggleton, Multi-scale simulation of L-selectin–PSGL-1-dependent homotypic leukocyte binding and rupture, Biomechanics and Modeling in Mechanobiology October 2010, Volume 9, Issue 5, pp 613–627 , DOI 10.1007/s10237-010-0201-2

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Subjects

Cell adhesion
Cell deformation
Immersed boundary method
Monte Carlo simulation
Receptor–ligand bond kinetics
High Performance Computing Facility (HPCF)

Abstract

L-selectin–PSGL-1-mediated polymorphonuclear (PMN) leukocyte homotypic interactions potentiate the extent of PMN recruitment to endothelial sites of inflammation. Cell–cell adhesion is a complex phenomenon involving the interplay of bond kinetics and hydrodynamics. As a first step, a 3-D computational model based on the Immersed Boundary Method is developed to simulate adhesion-detachment of two PMN cells in quiescent conditions. Our simulations predict that the total number of bonds formed is dictated by the number of available receptors (PSGL-1) when ligands (L-selectin) are in excess, while the excess amount of ligands influences the rate of bond formation. Increasing equilibrium bond length results in a higher number of receptor–ligand bonds due to an increased intercellular contact area. On-rate constants determine the rate of bond formation, while off-rates control the average number of bonds by modulating bond lifetimes. Application of an external pulling force leads to time-dependent on- and off-rates and causes bond rupture. Moreover, the time required for bond rupture in response to an external force is inversely proportional to the applied load and decreases with increasing off-rate.