Coherent Timescales and Mechanical Structure of Multicellular Aggregates.
Coherent Timescales and Mechanical Structure of Multicellular Aggregates.
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DOI：
10.1016/j.bpj.2018.04.025
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发表时间：
2018-06
影响因子：
3.4
通讯作者：
Miao Yu;Aria Mahtabfar;Paul Beelen;Yasir Demiryurek;D. Shreiber;J. Zahn;R. Foty;Liping Liu;Hao Lin
中科院分区：
文献类型：
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作者：
Miao Yu;Aria Mahtabfar;Paul Beelen;Yasir Demiryurek;D. Shreiber;J. Zahn;R. Foty;Liping Liu;Hao Lin
多细胞聚集体是一个很好的模型系统，以探讨组织生物力学的作用，在指定多细胞重组在胚胎发育和恶性肿瘤的侵袭。已知组织样球状体在经受压缩力时在长时间尺度（小时）下表现出液体样行为，这主要是因为细胞重排用于有效地消散所施加的应力。在短时间尺度（秒到分钟），在细胞重排之前，机械行为是惊人的不同。目前的工作使用形状松弛来研究团聚体的结构特征，并发现两个相干的时间尺度：一个在秒级，其他几十秒。这些时间尺度是通用的，在各种测试物种中是保守的，并且尽管在其他特性（如组织表面张力和粘附）上存在很大差异，但仍然存在。一个精确的数学理论是用来关联的时间尺度与机械性能，并揭示了骨料有一个相对较强的信封和一个异常的“软”的内部（弱体积弹性模量）。考虑到两层都由相同的单元（细胞）组成，这种特征是独特的，但与这种结构可以产生结构完整性和重塑所需的灵活性的事实相一致。此外，组织表面张力、弹性模量和粘度彼此成比例。考虑到这些组织水平的属性本质上来自细胞水平的属性，比例意味着后者的精确的共同调节，特别是细胞-介质和细胞-细胞界面上的张力。
Multicellular aggregates are an excellent model system to explore the role of tissue biomechanics in specifying multicellular reorganization during embryonic developments and malignant invasion. Tissue-like spheroids, when subjected to a compressive force, are known to exhibit liquid-like behaviors at long timescales (hours), largely because of cell rearrangements that serve to effectively dissipate the applied stress. At short timescales (seconds to minutes), before cell rearrangement, the mechanical behavior is strikingly different. The current work uses shape relaxation to investigate the structural characteristics of aggregates and discovers two coherent timescales: one on the order of seconds, the other tens of seconds. These timescales are universal, conserved across a variety of tested species, and persist despite great differences in other properties such as tissue surface tension and adhesion. A precise mathematical theory is used to correlate the timescales with mechanical properties and reveals that aggregates have a relatively strong envelope and an unusually "soft" interior (weak bulk elastic modulus). This characteristic is peculiar, considering that both layers consist of identical units (cells), but is consistent with the fact that this structure can engender both structural integrity and the flexibility required for remodeling. In addition, tissue surface tension, elastic modulus, and viscosity are proportional to each other. Considering that these tissue-level properties intrinsically derive from cellular-level properties, the proportionalities imply precise coregulation of the latter and in particular of the tension on the cell-medium and cell-cell interfaces.