Ohashi T, Ishii Y, Ishikawa Y, Matsumoto T, Sato M
Graduate School of Mechanical Engineering, Tohoku University, Sendai, Japan.
Biomed Mater Eng. 2002;12(3):319-27.
Local mechanical properties were measured for bovine endothelial cells exposed to shear stress using an atomic force microscopy (AFM), and the AFM indentations were simulated using a finite element method (FEM) to determine the elastic modulus. After exposure to shear stress, the endothelial cells showed marked elongation and orientation in the flow direction, together with significant decrease in the peak cell height. The applied force-indentation depth curve was obtained at seven different locations on the major axis of the cell surface and quantitatively expressed by the quadratic equation. The elastic modulus was determined by comparison of the experimental and numerical results. The modulus using our FEM model significantly became higher from 12.2+/-4.2 to 18.7+/-5.7 kPa with exposure to shear stress. Fluorescent images showed that stress fibers of F-actin bundles were mainly formed in the central portion of the sheared cells. The significant increase in the modulus may be due to this remodeling of cytoskeletal structure. The moduli using the Hertz model are 0.87+/-0.23 and 1.75+/-0.43 kPa for control and sheared endothelial cells respectively. This difference can be attributable to the differences in approximation functions to determine the elastic modulus. The elastic modulus would contribute a better understanding of local mechanical properties of the cells.
使用原子力显微镜（AFM）测量了暴露于剪切应力下的牛内皮细胞的局部力学性能，并使用有限元方法（FEM）模拟AFM压痕以确定弹性模量。暴露于剪切应力后，内皮细胞在流动方向上显示出明显的伸长和取向，同时细胞峰值高度显著降低。在细胞表面主轴上的七个不同位置获得了施加力-压痕深度曲线，并用二次方程进行了定量表达。通过比较实验结果和数值结果确定了弹性模量。使用我们的有限元模型，随着暴露于剪切应力，模量从12.2±4.2显著升高至18.7±5.7 kPa。荧光图像显示，F-肌动蛋白束的应力纤维主要在剪切细胞的中央部分形成。模量的显著增加可能归因于细胞骨架结构的这种重塑。对于对照和剪切后的内皮细胞，使用赫兹模型得到的模量分别为0.87±0.23和1.75±0.43 kPa。这种差异可归因于确定弹性模量的近似函数的差异。弹性模量将有助于更好地理解细胞的局部力学性能。
