Cell neighbor exchanges are integral to tissue rearrangements in biology, including development and repair. Often, these processes occur via topological T1 transitions analogous to those observed in foams, grains, and colloids. However, in contrast to those in nonliving materials, the T1 transitions in biological tissues are rate limited and cannot occur instantaneously due to the finite time required to remodel complex structures at cell-cell junctions. Here, we study how this rate-limiting process affects the mechanics and collective behavior of cells in a tissue by introducing this important biological constraint in a theoretical vertex-based model as an intrinsic single-cell property. We report that, in the absence of this time constraint, the tissue undergoes a glass transition with lowering of cell motility characterized by a sharp increase in the intermittency of cell-cell rearrangements. Remarkably, this glass transition disappears, as T1 transitions are temporally limited. As a unique consequence of limited rearrangements, we also find that the tissue develops spatially correlated populations of fast and slow cells, in which the fast cells organize into streamlike patterns and maintain optimally stable cell-cell contacts. The predictions of this work are compared with existing in vivo experiments in Drosophila pupal development.

中文翻译：

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受控相邻交换驱动上皮组织中的玻璃态行为、间歇性和细胞流

细胞邻居交换是生物学中组织重排不可或缺的一部分，包括发育和修复。通常，这些过程通过类似于在泡沫、颗粒和胶体中观察到的拓扑 T1 跃迁发生。然而，与非生命材料中的那些相比，生物组织中的 T1 转变速率有限，并且由于在细胞 - 细胞连接处重塑复杂结构所需的时间有限，因此无法立即发生。在这里，我们通过在基于顶点的理论模型中引入这一重要的生物学约束作为内在的单细胞特性，来研究这种限速过程如何影响组织中细胞的力学和集体行为。我们报告说，在没有这个时间限制的情况下，组织经历玻璃化转变，细胞运动性降低，其特征是细胞间重排的间歇性急剧增加。值得注意的是，这种玻璃化转变消失了，因为 T1 转变在时间上是有限的。作为有限重排的独特结果，我们还发现组织发展出空间相关的快速和慢速细胞群，其中快速细胞组织成流状模式并保持最佳稳定的细胞-细胞接触。这项工作的预测与现有的比较 其中快速细胞组织成流状模式并保持最佳稳定的细胞 - 细胞接触。这项工作的预测与现有的比较 其中快速细胞组织成流状模式并保持最佳稳定的细胞 - 细胞接触。这项工作的预测与现有的比较果蝇蛹发育的体内实验。