Epithelial cell monolayers show remarkable displacement and velocity correlations over distances of ten or more cell sizes that are reminiscent of supercooled liquids and active nematics. We show that many observed features can be described within the framework of dense active matter, and argue that persistent uncoordinated cell motility coupled to the collective elastic modes of the cell sheet is sufficient to produce swirl-like correlations. We obtain this result using both continuum active linear elasticity and a normal modes formalism, and validate analytical predictions with numerical simulations of two agent-based cell models, soft elastic particles and the self-propelled Voronoi model together with in-vitro experiments of confluent corneal epithelial cell sheets. Simulations and normal mode analysis perfectly match when tissue-level reorganisation occurs on times longer than the persistence time of cell motility. Our analytical model quantitatively matches measured velocity correlation functions over more than a decade with a single fitting parameter.
Bibliographical noteWe acknowledge many helpful discussions with C. Huepe, D. Matoz Fernandez,
K. Martens, I. Nathke, R. Sunyer, X. Trepat and C. J. Weijer. SH acknowledges support by the UK BBSRC (grant number BB/N009150/1-2). RS acknowledges support by the UK BBSRC (grant numbers BB/N009789/1-2). JMC was funded by BBSRC Research Grant BB/J015237/1. KK is funded by a BBSRC EASTBIO PhD studentship.
Data supporting the findings of this manuscript are available from the corresponding authors upon reasonable request.
Simulation and analysis code used in this study are available under an open source (GNU GPLv3.0) licence at: https://github.com/sknepneklab/SAMoS (http://doi.org/10.5281/zenodo.3616475).
- biological physics
- computational biophysics
- statistical physics, thermodynamics and nonlinear dynamics