Simulations of fluid flow in multicellular systems

Multicellular systems contain rich physical phenomena due to cell deformability, activity and inter-cellular interactions. However, many systems, such as wounded epithelia, developing blastocysts and elongating embryonic tissues contain measurable quantities of interstitial fluid. The influence of interstitial fluid on the mechanical properties of these systems is unknown, as is the degree to which cells can manipulate the flow. In this work, we present a model that captures the interactions and behavior of active cells and intercellular fluids. We consider dense systems of cells with porous membranes and active volume regulation by ion pumps, which lead to volume fluctuations and inter-cellular fluid flow. We show how cell volume fluctuations and fluid flow cells can alter cell shape and size distribution, cell neighbor-exchange rates, and tissue mechanics. We also investigate the impact of external flow on tissue structure and response as a function of cell permeability. This model serves as a framework with which many complex biological phenomena involving active cell mechanics and fluid flow can be investigated.