A microfluidic chamber-based approach to map the shear moduli of vascular cells and other soft materials.
A microfluidic chamber-based approach to map the shear moduli of vascular cells and other soft materials.
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DOI：
10.1038/s41598-017-02659-3
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发表时间：
2017-05-23
影响因子：
4.6
通讯作者：
Bartolák-Suki E
中科院分区：
文献类型：
--
作者：
Suki B;Hu Y;Murata N;Imsirovic J;Mondoñedo JR;de Oliveira CLN;Schaible N;Allen PG;Krishnan R;Bartolák-Suki E
人们对量化血管细胞和组织硬度越来越感兴趣。然而，大多数测量方法不能在存在生理流动的情况下评估刚度。我们开发了一种微流体方法，该方法允许在流动期间测量剪切模量（G）。该设计包括一个带有玻璃窗的腔室，允许使用直立或倒置的显微镜进行成像。通过重力控制流动以推动培养基通过腔室。将荧光珠缀合至样品表面并在流动之前和流动期间成像。根据图像计算珠位移，并将G计算为施加的剪切应力与测量的剪切应变的比率。流体-结构模拟表明，表面上的剪切应力不依赖于样品的刚度。我们的方法进行了验证，通过测量已知刚度的聚丙烯酰胺凝胶的模量。在人肺微血管内皮细胞中，G为20.4 ± 12 Pa，随着切应力的增加和非肌肉肌球蛋白II马达的抑制，G分别降低20%和22%。G表现出更大的细胞内比细胞间的变异性，它主要是由胞质溶胶。因此，我们的剪切模量显微镜可以映射G的空间分布的软材料，包括凝胶，细胞和组织，同时允许可视化的微观结构，如细胞骨架。
There is growing interest in quantifying vascular cell and tissue stiffness. Most measurement approaches, however, are incapable of assessing stiffness in the presence of physiological flows. We developed a microfluidic approach which allows measurement of shear modulus (G) during flow. The design included a chamber with glass windows allowing imaging with upright or inverted microscopes. Flow was controlled gravitationally to push culture media through the chamber. Fluorescent beads were conjugated to the sample surface and imaged before and during flow. Bead displacements were calculated from images and G was computed as the ratio of imposed shear stress to measured shear strain. Fluid-structure simulations showed that shear stress on the surface did not depend on sample stiffness. Our approach was verified by measuring the moduli of polyacrylamide gels of known stiffness. In human pulmonary microvascular endothelial cells, G was 20.4 ± 12 Pa and decreased by 20% and 22% with increasing shear stress and inhibition of non-muscle myosin II motors, respectively. The G showed a larger intra- than inter-cellular variability and it was mostly determined by the cytosol. Our shear modulus microscopy can thus map the spatial distribution of G of soft materials including gels, cells and tissues while allowing the visualization of microscopic structures such as the cytoskeleleton.