Possible roles of mechanical cell elimination intrinsic to growing tissues from the perspective of tissue growth efficiency and homeostasis
Fig 9
Improvement in tissue growth efficiency and homeostasis over time with cell competition through MCE in a mixed population.
(A) A simulation result for the time evolution of frequency distribution for a mechanical cell trait. In the case of perfect inheritance of the trait (i.e., h2 = 1), the frequency distribution drastically changes (left). At the same time, tissue-level fitness and density homeostasis are improved through tissue growth (right). In other words, intra-tissue evolution can occur. In contrast, in the case of no inheritance (i.e., h2 = 0), the frequency distribution of a cellular trait, the tissue fitness, and density homeostasis never changes. (B) Schematic diagrams of a model for inheritance of a mechanical trait. The trait of a daughter cell is inherited from its parent (blue) with probability q and is uniformly and randomly chosen from all the possibilities (red; among a discrete value of N-kinds) with probability 1-q (thus, q = 1 for perfect inheritance and q = 0 for no inheritance). (C) Growth curves for different values of heritability. The black solid lines are the curves obtained by simulations of vertex dynamics model. The green dashed lines show the growth curves obtained by the approximation (i), which is effective in cases with much higher heritability where each cell population of each trait can be regarded to grow independently (see Eq (9)). The purple dashed lines show the growth curves by the mean field approach (approximation (ii)), which is effective in a case with lower heritability (see Eqs (8)–(13)).