If Cell Mechanics Can Be Described by Elastic Modulus: Study of Different Models and Probes Used in Indentation Experiments
If Cell Mechanics Can Be Described by Elastic Modulus: Study of Different Models and Probes Used in Indentation Experiments
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DOI：
10.1016/j.bpj.2014.06.033
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发表时间：
2014-08-05
影响因子：
3.4
通讯作者：
Sokolov, Igor
中科院分区：
文献类型：
--
作者：
Guz, Nataliia;Dokukin, Maxim;Sokolov, Igor
在这里，我们调查的问题是否细胞，是高度异质性的对象，可以描述与弹性模量（有效杨氏模量）在一个自洽的方式。我们进行了比较分析的弹性模量来自压痕数据与原子力显微镜（AFM）对人类宫颈上皮细胞（正常和癌）。使用尖锐（锥形）和钝（2500 nm半径球）AFM探针。采用不同的弹性模型对压痕数据进行处理。细胞近似为均匀的弹性介质，其具有1）光滑的半球形边界（赫兹/斯奈登模型）或2）覆盖有糖萼层和膜突起的边界（“刷”模型）。这些近似的一致性进行了调查。具体来说，我们测试的压痕深度，这是假设在这些模型的弹性模量的独立性。我们证明，只有一个模型表现出一致性，在处理细胞作为一个均匀的弹性介质，即刷模型，当处理与钝AFM探针收集的压痕数据。弹性模量表现出很强的深度依赖性，在所有的模型：赫兹/Sneddon模型（没有刷考虑），当刷模型被应用到收集的数据与尖锐的锥形探头。我们的结论是，它是可能的描述的细胞体的弹性特性的有效弹性模量，在自洽的方式使用，当使用刷子模型来分析与一个沉闷的AFM探针收集的数据。这些结果的性质进行了讨论。
Here we investigated the question whether cells, being highly heterogeneous objects, could be described with the elastic modulus (effective Young's modulus) in a self-consistent way. We performed a comparative analysis of the elastic modulus derived from the indentation data obtained with atomic force microscopy (AFM) on human cervical epithelial cells (both normal and cancerous). Both sharp (cone) and dull (2500-nm radius sphere) AFM probes were used. The indentation data were processed through different elastic models. The cell was approximated as a homogeneous elastic medium that had either 1), smooth hemispherical boundary (Hertz/Sneddon models) or 2), the boundary covered with a layer of glycocalyx and membrane protrusions ("brush" models). Consistency of these approximations was investigated. Specifically, we tested the independence of the elastic modulus of the indentation depth, which is assumed in these models. We demonstrated that only one model showed consistency in treating cells as a homogeneous elastic medium, namely, the brush model, when processing the indentation data collected with the dull AFM probe. The elastic modulus demonstrated strong depth dependence in all models: Hertz/Sneddon models (no brush taken into account), and when the brush model was applied to the data collected with sharp conical probes. We conclude that it is possible to describe the elastic properties of the cell body by means of an effective elastic modulus, used in a self-consistent way, when using the brush model to analyze data collected with a dull AFM probe. The nature of these results is discussed.