Cell resolved, multiparticle model of plastic tissue deformations and morphogenesis

TL;DR

This paper introduces a 3D multiparticle mechanical model of embryonic tissue that captures elastic and plastic behaviors, linking microscopic parameters to macroscopic tissue properties and simulating active cellular processes.

Contribution

The model uniquely combines elastic beam forces with stochastic connectivity changes to realistically simulate tissue mechanics and morphogenetic movements.

Findings

Model reproduces realistic tissue elastic and plastic behavior.

Microscopic parameters can be inferred from macroscopic tissue properties.

Simulated tissue movements match empirical data from avian embryos.

Abstract

We propose a three dimensional mechanical model of embryonic tissue dynamics. Mechanically coupled adherent cells are represented as particles interconnected with elastic beams which can exert non-central forces and torques. Tissue plasticity is modeled by a stochastic process consisting of a connectivity change (addition or removal of a single link) followed by a complete relaxation to mechanical equilibrium. In particular, we assume that (i) two non-connected, but adjacent particles can form a new link; and (ii) the lifetime of links is reduced by tensile forces. We demonstrate that the proposed model yields a realistic macroscopic elasto-plastic behavior and we establish how microscopic model parameters affect the material properties at the macroscopic scale. Based on these results, microscopic parameter values can be inferred from tissue thickness, macroscopic elastic modulus and the magnitude and dynamics of intercellular adhesion forces. In addition to their mechanical role, model particles can also act as active simulation agents and modulate their connectivity according to specific rules. As an example, anisotropic link insertion and removal probabilities can give rise to local cell intercalation and large scale convergent extension movements. The proposed stochastic simulation of cell activities yields fluctuating tissue movements which exhibit the same autocorrelation properties as empirical data from avian embryos.