Large-scale demixing in a binary mixture of cells with rigidity disparity in biological tissues

Physical demixing on large scales of embryonic cell populations is fundamental to metazoan development, but whether a rigidity disparity alone is sufficient to driving large-scale demixing in a binary mixture of cell tissues is still an open question. To answer this question, we study mixing and demixing in a binary mixture of rigidity disparity cell tissues without heterotypic interactions using the Voronoi-based cellular model. Under suitable system parameters, the solid-like cells in the mixture can aggregate into a large cluster and the large-scale demixing occurs, which addresses that a rigidity disparity alone is sufficient to drive large-scale demixing. Remarkably, there exists an optimal temperature or rigidity disparity at which the binary mixture can be separated to the maximum extent. The necessary condition for the separation of mixtures is that the two types of cells are solid-like and liquid-like, respectively. The observation of robust demixing on large scales suggests that the sorting of progenitor cells may occur very early in the development process before robust heterotypic interfacial tensions are established. Our findings are relevant to understanding the mechanisms that drive cell sorting in confluent tissues.