Science Publications

Abstract In biology, specific cell adhesion is mediated by receptor-ligandinteractions. Consequently, its strength correlates with the strength of single receptor-ligandbonds that can be measured with a variety of techniques. However, whether single receptor-ligandbonds are truly present in an experiment is often a concern. In this paper, we present a Monte Carlosimulation of the adhesion between a microvillus-bearing cell and a ligand-coated substrate. In thesimulation, ligands were immobilized on the substrate either uniformly or in clusters of three andseven, while receptors were distributed uniformly on the microvillus tip and they moved randomly onthe cellular surface. How ligand clustering affects the adhesion frequency and forward rate constantwas studied. Other factors that were studied include receptor aggregation on the microvillus tip,ligand density, receptor density, contact time, and binding pocket size. In the case of uniformlydistributed ligands, our simulation results agree well with those obtained from probabilisticanalysis. We found that, even with clustered ligands on the substrate, most of the adhesion eventswere mediated by a single bond if the total adhesion frequency was less than 20%. Besides, ligandclustering decreased the total adhesion frequency and forward rate constant, but increased thesingle-bond adhesion frequency under comparable conditions. These findings should lend us someassistance in identifying single bonds in cell-substrate or cell-bead adhesion measurements and inillustrating some biological mechanisms that involve clustered ligands.

Keywords Ligands; Models, Biological; Monte Carlo Method; Receptors, Cell Surface

Annals of Biomedical Engineering
0090-6964, Volume 35, Issue 3, 2007, Pages 3-407
Shao,JY; Xu,G