Multiscale modelling of erythrocytes in Stokes flow
Multiscale modelling of erythrocytes in Stokes flow
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DOI：
10.1017/jfm.2011.332
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发表时间：
2011-11-01
影响因子：
3.7
通讯作者：
Zhu, Qiang
中科院分区：
文献类型：
--
作者：
Peng, Zhangli;Asaro, Robert J.;Zhu, Qiang
为了定量了解红细胞（红细胞，RBC）的分子结构与其机械响应之间的相关性，并预测生理条件下机械诱导的结构重塑，我们通过将红细胞膜的多尺度方法与周围斯托克斯流的边界元法（BEM）相结合，开发了一个计算模型。该膜在三个层面上进行描述：在整个细胞层面，采用有限元方法 (FEM) 将脂质双层和细胞骨架建模为两个不同的连续体壳层。细胞骨架的机械特性是从连接复合体的分子详细模型中获得的。血影蛋白是细胞骨架的主要蛋白质，使用基于分子的本构模型进行模拟。 BEM模型通过交错耦合算法与FEM模型耦合。利用该技术，我们首先模拟了毛细管流动中的红细胞动力学，发现蛋白质密度变化和双层骨架相互作用力比微移液器抽吸中的低得多，并且最大相互作用力出现在后缘。然后我们研究了红细胞在翻滚、踩罐和摆动运动期间剪切流中的机械响应。我们发现坦克踩踏频率对血浆粘度和膜粘度的依赖性与基准数据非常匹配。模拟结果表明，在坦克踩踏过程中，蛋白质密度变化对于健康红细胞来说并不显着，但对于双层骨架摩擦系数较小的细胞来说却很重要，这可能是遗传性球形红细胞增多症的情况。
To quantitatively understand the correlation between the molecular structure of an erythrocyte (red blood cell, RBC) and its mechanical response, and to predict mechanically induced structural remodelling in physiological conditions, we developed a computational model by coupling a multiscale approach of RBC membranes with a boundary element method (BEM) for surrounding Stokes flows. The membrane is depicted at three levels: in the whole cell level, a finite element method (FEM) is employed to model the lipid bilayer and the cytoskeleton as two distinct layers of continuum shells. The mechanical properties of the cytoskeleton are obtained from a molecular-detailed model of the junctional complex. The spectrin, a major protein of the cytoskeleton, is simulated using a molecular-based constitutive model. The BEM model is coupled with the FEM model through a staggered coupling algorithm. Using this technique, we first simulated RBC dynamics in capillary flow and found that the protein density variation and bilayer-skeleton interaction forces are much lower than those in micropipette aspiration, and the maximum interaction force occurs at the trailing edge. Then we investigated mechanical responses of RBCs in shear flow during tumbling, tank-treading and swinging motions. The dependencies of tank-treading frequency on the blood plasma viscosity and the membrane viscosity we found match well with benchmark data. The simulation results show that during tank-treading the protein density variation is insignificant for healthy erythrocytes, but significant for cells with a smaller bilayer-skeleton friction coefficient, which may be the case in hereditary spherocytosis.