细胞粘弹性产生机制的力学研究

Researchers usually believe that the viscoelasticity of cells mainly results from the viscoelasticity of cytoskeletal protein networks. The fundamental assumption is that the cell volume is conserved under external forces, or the cell can be directly treated as a semi-infinite body by ignoring the cell boundaries and the influences of the water exchange between the cell and environment on the cell volume and viscoelasticity. However, recent experiments found that cell volume plays an important role on the mechanical properties of cells. Therefore, this project will focus on a new mechanism of cell viscoelasticity, i.e., the viscoelasticity induced by the trans-membrane transport of water molecules and the following cell volume changes. We will combine theoretical modeling, numerical simulation and experimental validation to study the effects of the rate of water molecules transport on the volume and viscoelastic response of cells. We will further explore how the mode, magnitude and rate of loadings affect the cell viscoelasticity and cell volume. Lastly, we will study the interaction between different mechanisms of cell viscoelasticity and their relative contributions to the viscoelasticity of the whole cell. The results of this project will pave the way to the future development of cell mechanics, tissue engineering and biomedical engineering.

传统研究通常认为细胞的粘弹性主要来源于细胞骨架蛋白网络的粘弹性，其关键假设是在外力作用下细胞体积守恒，或者直接把细胞当成半无穷大体，从而忽略细胞边界以及细胞内外的水分子交换对细胞体积和细胞粘弹性的影响。但是最近的研究发现细胞体积对细胞的力学性质影响很大。因此，本项目将致力于研究一种全新的细胞粘弹性产生机制，即由于水分子的跨膜输运和细胞体积变化导致的细胞整体粘弹性响应。本项目将理论建模、数值计算和实验验证三种研究手段有机结合，研究水分子跨膜输运速率对细胞体积和粘弹性响应的影响，探索在不同加载方式、加载幅度、加载速率下细胞体积和粘弹性的变化，阐明不同的细胞粘弹性产生机制之间的相互关系和它们对细胞整体粘弹性的重要程度。本项目的研究成果将为细胞力学、组织工程学和生物医学工程的进一步发展奠定坚实的理论基础。

本项目针对细胞在各种外力加载情况下的粘弹性响应机制开展了较为系统和深入的理论和实验研究，取得了若干重要研究进展和创新成果：（1）揭示了细胞的粘附与脱粘动力学、细胞体积变化和细胞粘弹性响应的耦合规律；（2）阐明了细胞体积调节对细胞动态脱粘响应的影响；（3）发现了基底力学性质对细胞体积、形貌的调控作用；（4）提出了细胞表观粘弹性的新来源机制。本项目共在本领域重要国际、国内期刊发表论文10篇，包括《Physical Review Letters》，《J. Mech. Phys. Solids.》，《Nature Communications》，《Biophysical Journal》等杂志。并在项目执行期间培养研究生5人。

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