Department of Physics, University of California Santa Barbara, Santa Barbara, CA 93106, USA.
Soft Matter. 2021 Mar 21;17(11):3068-3073. doi: 10.1039/d0sm02027c. Epub 2021 Feb 17.
Recent experiments in various cell types have shown that two-dimensional tissues often display local nematic order, with evidence of extensile stresses manifest in the dynamics of topological defects. Using a mesoscopic model where tissue flow is generated by fluctuating traction forces coupled to the nematic order parameter, we show that the resulting tissue dynamics can spontaneously produce local nematic order and an extensile internal stress. A key element of the model is the assumption that in the presence of local nematic alignment, cells preferentially crawl along the nematic axis, resulting in anisotropy of fluctuations. Our work shows that activity can drive either extensile or contractile stresses in tissue, depending on the relative strength of the contractility of the cortical cytoskeleton and tractions by cells on the extracellular matrix.
最近在各种细胞类型中的实验表明，二维组织通常表现出局部向列有序性，并在拓扑缺陷的动力学中表现出伸展应力的证据。使用介观模型，其中组织流动是由与向列序参数耦合的波动牵引力产生的，我们表明，由此产生的组织动力学可以自发地产生局部向列有序性和伸展内应力。该模型的一个关键要素是假设在存在局部向列排列的情况下，细胞优先沿着向列轴爬行，从而导致波动的各向异性。我们的工作表明，活性可以根据皮质细胞骨架的收缩性和细胞对细胞外基质的牵引力的相对强度，在组织中驱动伸展或收缩应力。
