Pseudostratified epithelial tissues are characterized by tightly packed cells with minimal intercellular space. The forces exerted between neighbouring cells play a crucial role on the tissue shape and dynamics. However, the precise effects of these contact forces remain poorly understood and difficult to investigate in vivo.

To address this issue, we developed a particle-based modelling framework where each cell is represented geometrically, with cell-cell interactions governed by springs and non-overlapping constraints. The cells move towards minimizing a potential energy, leading to an overdamped Newtonian dynamics with noise and cell division. The model can be formulated as a generalized gradient flow and it is implemented using a first-order position-based dynamics algorithm.

After validating the model against in vivo data, a combination of in silico and in vivo experiments has shown how nuclear movements influence cell distribution and tissue morphology over time. Additionally, by incorporating cell heterogeneity into the model, we were able to investigate how defects in individual cells may drive cell extrusion - a key step in embryo development and cancer metastasis.

Joint work with Steffen Plunder (Kyoto), Sara Merino-Aceituno (Vienna), Pierre Degond (Toulouse) and Eric Theveneau's lab (CBI, Toulouse)