Simulation of Pseudopodia Extension and Retraction in the Neutrophil

William Marganski, Boston University

Neutrophils extend pseudopodia in the presence of N-formyl-methyl-leucyl-phenylalanine (fMLP), which is a by-product of bacterial metabolism. One theory that attempts to explain the mechanisms by which the outward pushing of the pseudopodia evolves, is the swelling model. In this model new actin filament networks, which form underneath the site of fMLP binding, swell due to interfilament repulsion and filament-solvent attraction, thus forming a pseudopodia. Using finite element analysis, we have implemented the swelling model to simulate pseudopodia extension and retraction and neutrophil locomotion in a micropipet. Our results indicate that the swelling model can explain a number of observations seen in the experimental setting. These include data on the kinematics of pseudopodia extension and retraction, the distribution of the cytoskeleton, the geometry of extending and retracting pseudopodia, and the physical force generated by a neutrophil during active movement.

Abstract Author(s): William Marganski