单层细胞群落结构、动力学和张力的极简模型
A minimal model for structure, dynamics, and tension of monolayered cell colonies
AI总结：
提出带吸引力的新型 active Brownian particle model，通过宽势阱最小值赋予粒子摆动空间，实现中等推进力下单层细胞群落的流体-真空共存，并预测了边缘极性取向、拉伸应力及强推进下的细胞簇脱落现象。
摘要：
组织中细胞的运动是一种普遍存在的现象。特别是在体外的单层细胞群落中，观察到群落深处具有类似漩涡运动的显著集体行为，同时群落保持凝聚状态，边缘没有一个细胞逃逸。因此，群落内部表现出类似液体的性质，与外部无细胞的“真空”共存。黏附力如何才能强到足以将细胞聚集在一起，同时又不使系统陷入玻璃态？什么样的极简模型能描述这种行为？内部流动性还会产生哪些其他活性特征？我们提出了一种带吸引力的新型 active Brownian particle model，其相互作用势具有较宽的最小值，赋予粒子足够的摆动空间以集体处于流体状态。我们证明，在中等推进力下，该模型能产生上述的流体-真空共存。此外，群落流体特性与凝聚性的结合导致细胞极性在边缘呈现向外的优先取向，进而引发群落内的拉伸应力——正如在 epithelial sheets 实验中观察到的那样。在更强推进力下，预测会发生细胞簇的集体脱落。进一步增加细胞极性与速度方向的排列偏好，会导致协调的漩涡运动增强、拉伸应力增加以及细胞簇脱落。
英文摘要：
The motion of cells in tissues is an ubiquitous phenomenon. In particular, in monolayered cell colonies in vitro, pronounced collective behavior with swirl-like motion has been observed deep within a cell colony, while at the same time, the colony remains cohesive, with not a single cell escaping at the edge. Thus, the colony displays liquid-like properties inside, in coexistence with a cell-free "vacuum" outside. How can adhesion be strong enough to keep cells together, while at the same time not jam the system in a glassy state? What kind of minimal model can describe such a behavior? Which other signatures of activity arise from the internal fluidity? We propose a novel active Brownian particle model with attraction, in which the interaction potential has a broad minimum to give particles enough wiggling space to be collectively in the fluid state. We demonstrate that for moderate propulsion, this model can generate the fluid-vacuum coexistence described above. In addition, the combination of the fluid nature of the colony with cohesion leads to preferred orientation of the cell polarity, pointing outward, at the edge, which in turn gives rise to a tensile stress in the colony -- as observed experimentally for epithelial sheets. For stronger propulsion, collective detachment of cell clusters is predicted. Further addition of an alignment preference of cell polarity and velocity direction results in enhanced coordinated, swirl-like motion, increased tensile stress and cell-cluster detachment.
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