Alexander Nestor-Bergmann: Stress and Disorder in a Confluent Epithelium

Characterising the mechanical properties of geometrically complex tissues is an essential step in understanding how cell behaviours can be controlled by mechanical cues. Working in the context of a popular vertex-based model, I will derive expressions for the linearised relation between tissue-level stress and strain about a deformed base state, showing that mechanically homogeneous tissues can exhibit anisotropic mechanical properties. The model captures observations of an epithelium from a Xenopus embryo, where uniaxial stretching induces spatial ordering, with cells under net tension (compression) tending to align with (against) the direction of stretch, but with the stress remaining heterogeneous at the single-cell level. By deriving expressions for the elastic tissue moduli as direct sums over cells, I will demonstrate that tissue properties can be tuned to a regime with high elastic shear resistance but low resistance to area changes, or vice versa.
Reference: Nestor-Bergmann, A. et al. (2018). Mechanical characterization of disordered and anisotropic cellular monolayers. Physical Review E, 97(5), 052409.