Modeling epithelial tissues as active-elastic sheets reproduce contraction pulses and predict rip resistance

Confluent epithelial tissues can be viewed as soft active solids, as their individual cells contract in response to local conditions. Little is known about the emergent properties of such materials. Empirical observations have shown contraction waves propagation in various epithelia, yet the governing mechanism, as well as its physiological function, is still unclear. Here we propose an experiment-inspired model for such dynamic epithelia. We show how the widespread cellular response of contraction-under-tension is sufficient to give rise to propagating contraction pulses, by mapping numerically and theoretically the consequences of such a cellular response. The model explains observed phenomena but also predicts enhanced rip-resistance as an emergent property of such cellular sheets. Unlike healing post-rupture, these sheets avoid it by actively re-distributing external stresses across their surface. The mechanism is relevant to a broad class of tissues, especially such under challenging mechanical conditions, and may inspire engineering of synthetic materials. Observations on confluent epithelial tissues show the emergence of dynamic contraction patterns that are suspected to be governed mechanically. Here, the authors propose a model for epithelial sheets and show that cells’ Extension-Induced-Contraction response explains experimentally-observed contraction pulses, that along with a cell softening response enhances epithelial resistance to rupture.