Mechanical response analysis and power generation by single-cell stretching
Mechanical response analysis and power generation by single-cell stretching
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DOI：
10.1002/cphc.200400417
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发表时间：
2005-04-01
期刊：
影响因子：
2.9
通讯作者：
Ott, A
中科院分区：
文献类型：
--
作者：
Micoulet, A;Spatz, JP;Ott, A
为了收集有关生理条件下机械扰动引起的细胞反应的有用信息，设计了一种基于微扰的技术，该技术允许在体外单个细胞上精确施加任意力或变形历史。这些调查的基本要求是一个机制，应用自动细胞力和诱导变形检测系统的基础上光纤力传感和闭环控制。由于可以充分消除由于热梯度引起的机械漂移（这些梯度是由细胞观察室局部加热到37摄氏度引起的），因此装置所需的机械稳定性可以持续几个小时。在机械表征过程中，用光学显微镜观察细胞，从而能够同时观察细胞形状和细胞内形态变化。要么观察细胞伸长作为对恒定载荷的反应，要么测量细胞力作为对恒定变形的响应。可以区分被动粘弹性变形和主动细胞响应。在收缩期间产生的有功功率在P-max = 10（-16）瓦的范围内，其对应于在10 k（B）T/分子下的2500个ATP分子（-1）。收缩功率与耗散功率之比估计在10（-2）的范围内。细胞所支持的最大力表明，收缩必须涉及大约10（4）个分子马达。这表明能量转换效率约为0.5。我们的研究结果表明，除了招聘的细胞收缩元素后，机械刺激，细胞骨架变得越来越交联的机械拉力。定量应力-应变数据，如本文所述，可用于测试描述细胞对机械刺激反应的物理模型。
To harvest useful information about cell response due to mechanical perturbations under physiological conditions, a cantilever-based technique was designed, which allowed precise application of arbitrary forces or deformation histories on a single cell in vitro. Essential requirements for these investigations are a mechanism for applying an automated cell force and an induced-deformation detection system based on fiber-optical force sensing and closed loop control. The required mechanical stability of the setup can persist for several hours since mechanical drifts due to thermal gradients can be eliminated sufficiently (these gradients are caused by local heating of the cell observation chamber to 37 degrees C). During mechanical characterization, the cell is visualized with an optical microscope, which enables the simultaneous observation of cell shape and intracellular morphological changes. Either the cell elongation is observed as a reaction against a constant load or the cell force is measured as a response to constant deformation. Passive viscoelastic deformation and active cell response can be discriminated. The active power generated during contraction is in the range of P-max = 10(-16) Watts, which corresponds to 2500 ATP moleculess(-1) at 10 k(B)T/molecule. The ratio of contractive to dissipative power is estimated to be in the range of 10(-2) The highest forces supported by the cell suggest that about 10(4) molecular motors must be involved in contraction. This indicates an energy-con version efficiency of approximately 0.5. Our findings propose that, in addition to the recruitment of cell-contractile elements upon mechanical stimulation, the cell cytoskeleton becomes increasingly crosslinked in response to a mechanical pull. Quantitative stress-strain data, such as those presented here, may be employed to test physical models that describe cellular responses to mechanical stimuli.