Non-Hertzian approach to analyzing mechanical properties of endothelial cells probed by atomic force microscopy

被引:115
作者
Costa, KD [1 ]
Sim, AJ
Yin, FCP
机构
[1] Columbia Univ, Dept Biomed Engn, New York, NY 10027 USA
[2] Washington Univ, Dept Biomed Engn, St Louis, MO USA
来源
JOURNAL OF BIOMECHANICAL ENGINEERING-TRANSACTIONS OF THE ASME | 2006年 / 128卷 / 02期
关键词
cell mechanics; stress fibers; actin cytoskeleton;
D O I
10.1115/1.2165690
中图分类号
Q6 [生物物理学];
学科分类号
071011 ;
摘要
Detailed measurements of cell material properties are required for understanding how cells respond to their mechanical environment. Atomic force microscopy (AFM) is an increasingly popular measurement technique that uniquely combines subcellular mechanical testing with high-resolution imaging. However; the standard method of analyzing A FM indentation data is based on a simplified "Hertz" theory that requires unrealistic assumptions about cell indentation experiments. The objective of this study was to utilize an alternative "pointwise modulus" approach, that relaxes several of these assumptions, to examine subcellular mechanics of cultured human aortic endothelial cells (HAECs). Data from indentations in 2- to 5-mu m square regions of cytoplasm reveal at least two mechanically distinct populations of cellular material. Indentations colocalized with prominent linear structures in AFM images exhibited depth-dependent variation of the apparent pointwise elastic modulus that was not observed at adjacent locations devoid of such structures. The average pointwise modulus at an arbitrary indentation depth of 200 nm was 5.6 +/- 3.5 kPa and 1.5 +/- 0.76 kPa (mean +/- SD, n=7) for these two material populations, respectively The linear structures in AFM images were identified by fluorescence microscopy, as bundles of f-actin, or stress fibers. After treatment with 4 mu M cytochalasin B, HAECs behaved like a homogeneous linear elastic material with an apparent modulus of 0.89 +/- 0.46 kPa. These findings reveal complex mechanical behavior specifically associated with actin stress fibers that is not accurately described using the standard Hertz analysis, and may impact how HAECs interact with their mechanical environment.
引用
收藏
页码:176 / 184
页数:9
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