力学系与湍流国家重点实验室学术报告12.29(报告人：Shaofan Li)
发布时间: 2009-12-29 10:09:00
SEMINAR SERIES
北京大学工学院 
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力学与空天技术系
湍流与复杂系统国家重点实验室
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题目：Simulation of Adhesive Contact of Stem Cells
Shaofan Li
Department of Civil and Environmental Engineering,
University of California, Berkeley, CA94720, USA; E-mail: shaofan（at）berkeley.edu
报告内容摘要
Stem cell is the master cell of human being, and the differentiation of stems is the mystery of our time. Recently, experimental results have shown that the rigidity of the substrate has significant influence on the differentiation of stem cells or the fate of stem cells. To explain such bio-physical or physiology phenomenon has been the current focus of stem cell research as well as cell mechanics research.
In this talk, we shall discuss multiscale modeling and simulations of soft elasticity and focal adhesion of cells. In particular, our research work is focused on modeling and simulation of contact and adhesion of stem cells on substrates with different rigidities and microstructures. We are attempting to answer two fundamental questions: (1) How does the stiffness of a substrate affect the adhesion of stem cells? and (2) How is it related to mechanotransduction of cells? What is the origin of the focal adhesion?
Considering the size of the stem cells, from a few mm to 100 mm, and their special characteristics, we have proposed a soft matter model to simulate the contact and adhesion of stem cells with substrate by employing a multiscale adhesion/contact sub-model that is aimed to simulate specific site adhesion i.e. interactions between ligands and receptors. A coarse-grained adhesion and contact model is proposed, which may describe the interaction between ligands and receptors, steric force, and colloidal interactions between the cells and substrates in general. We have applied the multiscale contact/adhesion model in conjunction with the soft matter cell model to study contact and adhesion process of stem cells. By modeling the stem cell as an isotropic amphiphilic aggregate, it may be shown that under external stimulus the cell can change its microstructure, conformation, as well as configuration.
In this presentation, we shall address several modeling and computation challenges and the solutions that we have adopted: (1) Since both the cell and the substrate (culture) undergo extremely large defor- mation, what kind of discretization, interpolation, and integration algorithms may work? (2) The layer of focal adhesion is essentially a complex fluid layer or liquid gel that is capable of self-assemble; How do we simulate it? (3) ow to stabilize the convection related numerical instability? (4) Is the current soft matter? model well posed in the sense of physical principle, e.g. satisfying the principle of frame-indifference? (5) Are the current soft matter cell models computationally, or mathematically, well posed without causing spurious solutions ?
主持人：段慧玲 特聘研究员
时 间：12月29日（周二）下午2:00~3:30
地 点：力学楼434会议室
欢迎广大师生光临！