Silke Henkes, University of Aberdeen
Cell sheets as Soft Active Matter
Epithelial cell sheets are collections of active, motile cells interacting through adhesion, contraction, division, intercalations and death. We first study simplified models where we analyze the effects of individual active drivers, i.e. self-propulsion or division and death, and then move to a full model, the hybrid active vertex model (AVM) that combines the standard vertex tissue model with active matter dynamics.
In the simplified models, we find that persistent self-propulsion leads to long-range displacement correlations, in agreement both with analytical arguments on normal mode fluctuation spectra and experimental results. Division and death fluidize the system in steady-state through localized strain events, in agreement with an adapted Hébraud-Lequeux model.
For the AVM, we establish a duality between cell centres and vertex coordinates and use it to map forces exerted onto vertices into forces on cell centres, thus allowing efficient implementation into overdamped active matter simulations. As a direct consequence of this active dynamics, cell rearrangements, most notably T1 transitions, arise naturally in the model. This allows us to simulate the emergent dynamical motion patterns of tens of thousands of epithelial cells, and directly establish links to the simplified models.
In collaboration with: Rastko Sknepnek (University of Dundee), Kirsten Martens, Daniel Matoz-Fernandez, Eric Bertin (Université Joseph Fourier Grenoble), Kaja Kostanjevec (Institute for Medical Sciences, University of Aberdeen), Kees Weijer (School of Life Sciences, University of Dundee)