Role of intercellular adhesion in modulating tissue fluidity

Abstract: Tuning cell rearrangements is essential in collective cell movement that underlies cancer progression, wound repair, and embryonic development. A key question is how tissue material properties and morphology emerge from cellular factors such as cell-cell adhesion. Here, we introduce a two-dimensional active force-based model of tissue monolayers that captures the liquid-to-solid transition exhibited by tissues. Unlike the Vertex and Voronoi models, our model shows that reducing intercellular adhesion in near-confluent tissues leads to spontaneous neighbor exchanges and fluidization. Near the liquid-solid phase boundary, we also found glassy behavior characterized by subdiffusive dynamics, swirling cell motion, and non-Gaussian exponential tails in displacement distributions. These exponential tails collapse onto a single master curve, suggesting a universal 'diffusion length' in the glassy regime. Notably, we demonstrate that structural parameters based on cell shape cannot always distinguish tissue phases due to huge cell shape fluctuations that are not observed in Vertex and Voronoi models. Our general simulation framework streamlines previous approaches by removing many arbitrary features and can reproduce known model behaviors under different conditions, offering potential applications in developmental biology and physiology.