相场动力学模型研究细胞运动中的形态变化

Cell Morphodynamics via Phase Field Dynamics Model

细胞运动涉及细胞骨架和细胞之间的相互协同作用,其中包括细胞膜上的表面张力作用和曲面弹性能的作用、细胞内肌动蛋白聚合时产生的"突起力"和肌球蛋白作用下的"收缩力"、细胞和基板的相互作用等.为此,我们基于相场动力学理论和反应扩散理论,将细胞内肌动蛋白的动态组装行为、肌球蛋白的生理作用、以及细胞与基体的相互作用等因素与细胞的形态变化和运动相耦合关联起来建立新的细胞运动机制模型,以研究细胞运动中的形态及速度变化.通过该理论模型预测在一定生理条件下细胞稳态的形态和运动速度,研究结果表明理论结果和仿生实验结果相对吻合.此外,我们还系统研究了细胞运动速度及形态对肌动蛋白与肌球蛋白浓度以及肌动蛋白组装成微丝的速率常数的依赖关系.同时,该理论方法还有望进一步拓展到细胞收缩、细胞分裂、细胞在流动场的运动等复杂体系.

Cell motion is a complex biological process that involves the cooperative interactions between the cytoskeleton and cell membrane, and these interactions generally include these interactive energies generated from the surface tension and the bending elastic energy of the cell membrane, the ＂protrusive＂ and ＂contractile＂ forces separately driven by actin polym- erization into cytoskeletons and myosin contraction, and the adhesion between the cell and the substrate. Herein, one compu- tational model based on the phase field method and the reaction-diffusion model is subsequently developed to describe this complicated biological process, coupling the cell movement and cell morphologenis with the dynamic behaviors of actin assemble into actin filaments, the physiological functions of myosin, and the interaction between the cell and the substrate. In the computational model for cell motion, the moving boundary with physical membrane properties is proposed to numerically solve the problem involved in the computational efficiency. The fish keratocytes, fast moving cells that maintain their mor- phology, are applied in the present study, and the related system parameters are chosen. The steady state and movement ve- locity of cells are obtained with a wide range of aspect ratios and movement velocities in the computational model, which are found to be well in agreement with the associated experimental results in vitro. In addition, the dependences of the movement velocity and the steady state of the cells are in detail studied on system parameters that are the concentrations of the actin and myosin, as well as the actin rate constants. It will be straightforward to extend this method to more complicated systems, such as cell contraction, cell division, and cell movement in actin flow and shear flow.