Institute of Biomechanics and Medical Engineering, Engineering Mechanics Department, School of Aerospace, Tsinghua University, Beijing 100084, China.
Soft Matter. 2014 Jul 14;10(26):4603-8. doi: 10.1039/c3sm52914b.
An experimental observation has been puzzling scientists for years: cells tend to align perpendicular to cyclic uniaxial strain, but parallel to external static strain. Recent experimental results demonstrate that both the magnitude of the external strain and the cell contractility manipulate the cells' orientation under cyclic uniaxial strain. In light of these reports, we introduce a minimum free energy model to explain the different orientation tendencies of cells subjected to external strain, and elucidate the significant role of cell contractility in this issue. With the present model, we successfully explain a series of well-documented phenomena: (1) cells orient nearly parallel to static uniaxial strain; (2) cell alignment depends on the magnitude of the cyclic uniaxial strain; (3) under cyclic uniaxial stretch, a tensioned contractility results in a strengthened perpendicular alignment of the cells, whereas a contractility relaxation results in a nearly parallel alignment. In addition, this model also successfully describes the functional relationship between cell contractility and substrate stiffness.
多年来，一个实验观察结果一直令科学家感到困惑：细胞倾向于垂直于循环单轴应变排列，但与外部静态应变平行。最近的实验结果表明，外部应变的大小和细胞收缩力都可以操纵细胞在循环单轴应变下的取向。有鉴于此，我们引入了一个最小自由能模型来解释细胞在外力作用下的不同取向趋势，并阐明了细胞收缩力在这一问题中的重要作用。通过目前的模型，我们成功地解释了一系列有充分文献记载的现象：（1）细胞几乎与静态单轴应变平行排列；（2）细胞排列取决于循环单轴应变的大小；（3）在循环单轴拉伸下，紧张的收缩力导致细胞的垂直排列增强，而收缩力的松弛则导致几乎平行的排列。此外，该模型还成功地描述了细胞收缩力和基质刚度之间的功能关系。
