2D Epithelial Tissue Modeling Revisited: Incorporating 3D Effects and Actin Fiber Mechanics

The mechanical response and integrity of epithelial tissues is crucial for their function. Traditional two-dimensional vertex models predict a loss of tissue rigidity when cell-cell adhesion overcomes perimeter elasticity, but is contradicted by our experiments on Madin-Darby canine kidney cells. Resolving cell shapes along the apical-basal axis reveals that elasticity is properly modeled by three-dimensional shell theory, and that the observed cell cross sections are altered both by this novel elasticity modeling and by the presence of actin fiber bundles on the basal side. We present GPU accelerated 2D tissue models using CellGPU taking the anisotropic mechanics of the fiber bundles into account. Modeling results are compared with experimentally obtained patterns of fiber orientation in normal tissues as well as tissues treated with blebbistatin and cytochalasin-D, disrupting actomyosin contractility. The relationship between cell shapes and tissue rigidity is altered considerably from existing models, informing tissue diagnostics from morphological indicators.