The compaction of gels by cells: a case of collective mechanical activity
The compaction of gels by cells: a case of collective mechanical activity
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DOI：
10.1039/b822897c
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发表时间：
2009-03-01
影响因子：
2.5
通讯作者：
Bausch, Andreas R.
中科院分区：
文献类型：
--
作者：
Fernandez, Pablo;Bausch, Andreas R.
为了理解机械转导，收缩细胞与其弹性环境之间的串扰所导致的纯机械现象必须与对机械信号的适应性反应区分开来。在这里，我们回顾了嵌入细胞对自由悬浮的胶原凝胶的致密作用，其中一小部分细胞(成骨细胞和成纤维细胞)将周围的基质致密两个数量级。结合微图案化和延时应变映射，我们发现凝胶的紧实度是由周围基质的机械方面决定的。首先，它是一种边界效应：压实从基质的边缘传播到大块。其次，由于单元的非线性力学和边界条件，单元施加的应力不可逆地压缩矩阵并使其各向异性。第三，细胞极化和排列在时间上遵循，似乎是凝胶压实的结果，这与目前的机械传感概念不一致。最后，我们对阈值细胞密度的观察表明，凝胶压实是一种协同效应，揭示了细胞之间通过基质的机械相互作用。细胞收缩和周围基质力学之间错综复杂的相互作用提供了一个重要的组织原理，对许多生理过程，如组织发育具有重要意义。
To understand mechanotransduction, purely mechanical phenomena resulting from the crosstalk between contractile cells and their elastic surroundings must be distinguished from adaptive responses to mechanical cues. Here, we revisit the compaction of freely suspended collagen gels by embedded cells, where a small volume fraction of cells (osteoblasts and fibroblasts) compacts the surrounding matrix by two orders of magnitude. Combining micropatterning with time-lapse strain mapping, we find gel compaction to be crucially determined by mechanical aspects of the surrounding matrix. First, it is a boundary effect: the compaction propagates from the edges of the matrix into the bulk. Second, the stress imposed by the cells irreversibly compacts the matrix and renders it anisotropic as a consequence of its nonlinear mechanics and the boundary conditions. Third, cell polarization and alignment follow in time and seem to be a consequence of gel compaction, at odds with current mechanosensing conceptions. Finally, our observation of a threshold cell density shows gel compaction to be a cooperative effect, revealing a mechanical interaction between cells through the matrix. The intricate interplay between cell contractility and surrounding matrix mechanics provides an important organizing principle with implications for many physiological processes such as tissue development.