Pushing off the walls: a mechanism of cell motility in confinement

TL;DR

This paper introduces a new cell motility mechanism driven by actin polymerization and geometric confinement, independent of adhesion, with implications for understanding cell migration in tissues.

Contribution

It presents an analytical model showing spontaneous cell motion in confinement without adhesion or myosin activity, expanding current understanding of cell motility mechanisms.

Findings

Cells can move in confinement without adhesion.

Velocity can exceed polymerization rate.

Myosin activity enhances motility.

Abstract

We propose a novel mechanism of cell motility, which relies on the coupling of actin polymerization at the cell membrane to geometric confinement. We consider a polymerizing viscoelastic cytoskeletal gel confined in a narrow channel, and show analytically that spontaneous motion occurs. Interestingly, this does not require specific adhesion with the channel walls, and yields velocities potentially larger than the polymerization velocity. The contractile activity of myosin motors is not necessary to trigger motility in this mechanism, but is shown quantitatively to increase the velocity. Our model qualitatively accounts for recent experiments which show that cells without specific adhesion proteins are motile only in confined environments while they are unable to move on a flat surface, and could help in understanding the mechanisms of cell migration in more complex confined geometries such as living tissues.