Department of Physics and Center for Complex Systems, National Central University, Jhongli, Taiwan 32001, Republic of China.
Phys Rev Lett. 2022 Sep 30;129(14):148102. doi: 10.1103/PhysRevLett.129.148102.
We experimentally demonstrate the two-stage structural and slowing-down percolating transitions, followed by the confluent transition in the densifying cancer cell monolayers from the dilute state, and investigate their impacts on collective cell dynamics. It is found that cells aggregate into clusters at low cell density. With increasing cell number density, the structural percolation through the formation of a large cell cluster percolating through the space precedes the dynamical percolation transition of forming a percolating cluster of slow cell elements. Both percolating transitions exhibit scale-free scaling behaviors of cluster size distributions and fractal structures, similar to those of the universality class of 2D nonequilibrium systems governed by percolation theory. Dynamically, at low cell density, cell aggregation enhances cooperative motion. The structural percolation leads to slower motion, especially with stronger suppression for the high-frequency modes in the turbulent-like velocity power spectra. The following slowing-down percolation associated with the onset of cell crowding in regions occupied by cells further enhances dynamical slowing-down, and suppresses the increasing trend of dynamical heterogeneity and the steepening of the power spectrum of motion, until their reversions after the confluent transition.
我们通过实验演示了从稀疏状态致密化癌细胞单层中的两阶段结构和减速渗流转变，以及随之而来的融合转变，并研究了它们对集体细胞动力学的影响。结果表明，细胞在低细胞密度下聚集形成簇。随着细胞数密度的增加，结构渗流通过形成一个大的细胞簇在空间中渗透，先于形成一个缓慢细胞元素的渗流簇的动力学渗流转变。这两种渗流转变都表现出无标度的簇大小分布和分形结构的标度行为，类似于由渗流理论控制的二维非平衡系统的普适类。在动力学上，在低细胞密度下，细胞聚集增强了协同运动。结构渗流导致运动速度变慢，特别是在类似湍流的速度功率谱中对高频模式的抑制更强。随后的减速渗流与细胞拥挤的出现有关，在细胞占据的区域进一步增强了动力学减速，并抑制了动力学异质性的增加趋势和运动功率谱的陡峭度，直到融合转变后的逆转。
