Geometric signatures of tissue surface tension in a three-dimensional model of confluent tissue

Dense biological tissues ensure that cell types performing different roles remain segregated by maintaining sharp interfaces. To better understand the mechanisms for such sharp compartmentalization, we study the effect of an imposed heterotypic tension at the interface between two distinct cell types in a fully 3D model for confluent tissues. We find that cells rapidly sort and self-organize to generate a tissue-scale interface between cell types, and cells adjacent to this interface exhibit signature geometric features including nematic-like ordering, bimodal facet areas, and registration of cell centers on either side of the two-tissue interface. The magnitude of these features scale directly with the magnitude of imposed tension, suggesting that experiments might estimate the magnitude of tissue surface tension between two tissue types simply by segmenting a 3D tissue. To uncover the underlying physical mechanisms driving these geometric features, we develop two simple toy models that identify an energy competition between bulk cell shapes and two-tissue interface area. When the area term dominates, changes to neighbor topology are costly, pinning neighbor topologies and generating the observed geometric features.