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Cell dance, a persistence issue

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Epithelial cell monolayers, that can be thought of as an experimental model of biological tissues, show remarkable displacement and velocity correlations over distances of ten or more cell sizes. These correlated displacements are reminiscent of qualitatively similar cooperative moves observed in supercooled liquids as well as in active nematics.

In the current issue of Nature Communications, a collaboration involving a researcher at LIPhy and researchers from the universities of Bristol, Dundee and Aberdeen in the UK, shows that the main observed features of collective cell motion in epithelial cell monolayers can be described within the framework of dense active matter. More specifically, they argue that persistent uncoordinated cell motility coupled to the collective elastic modes of the cell sheet is sufficient to produce the swirl-like correlations observed in confluent corneal epithelial cell sheets. The modeling approach combines on the one hand a continuum active linear elasticity and a normal modes formalism based on the cell-level dynamics, and on the other hand numerical simulations of two models of motile cells, a model of soft elastic particles and a model where confluent cells are described through a Voronoi tesselation. On a theoretical level, a key result is that the correlation length of the velocity field scales as the square root of the persistence time of the self-propulsion force, whose orientation is random. A large persistence time with respect to the relaxation time scale of the cell dynamics thus leads to cell motions that are correlated over length scales much larger than cell size.

PNGFigure caption : velocity field (red arrow) in a simulation of the self-propelled soft particles model at high packing fraction, with a large persistence time of the self-propulsion force. Particle color also codes for the particle speed (with dark blue corresponding to the lowest speed), to better visualize the spatial correlations of the speed of slow particles.

Voir en ligne : Dense active matter model of motion patterns in confluent cell monolayers, Silke Henkes, Kaja Kostanjevec, J. Martin Collinson, Rastko Sknepnek & Eric Bertin Nature Communications March 2020