Duclos G, Blanch-Mercader C, Yashunsky V, Salbreux G, Joanny J-F, Prost J, Silberzan P
Laboratoire PhysicoChimie Curie, Institut Curie, PSL Research University - Sorbonne Universités, UPMC - CNRS. Equipe labellisée Ligue Contre le Cancer ; 75005, Paris, France.
The Francis Crick Institute, London, UK.
Nat Phys. 2018 Jul;14(7):728-732. doi: 10.1038/s41567-018-0099-7. Epub 2018 Apr 16.
In embryonic development or tumor evolution, cells often migrate collectively within confining tracks defined by their microenvironment 1,2. In some of these situations, the displacements within a cell strand are antiparallel 3, giving rise to shear flows. However, the mechanisms underlying these spontaneous flows remain poorly understood. Here, we show that an ensemble of spindle-shaped cells plated in a well-defined stripe spontaneously develop a shear flow whose characteristics depend on the width of the stripe. On wide stripes, the cells self-organize in a nematic phase with a director at a well-defined angle with the stripe's direction, and develop a shear flow close to the stripe's edges. However, on stripes narrower than a critical width, the cells perfectly align with the stripe's direction and the net flow vanishes. A hydrodynamic active gel theory provides an understanding of these observations and identifies the transition between the non-flowing phase oriented along the stripe and the tilted phase exhibiting shear flow as a Fréedericksz transition driven by the activity of the cells. This physical theory is grounded in the active nature of the cells and based on symmetries and conservation laws, providing a generic mechanism to interpret in vivo antiparallel cell displacements.
在胚胎发育或肿瘤演变过程中，细胞常常在由其微环境定义的受限轨迹内集体迁移1,2。在其中一些情况下，细胞链内的位移是反平行的3，从而产生剪切流。然而，这些自发流动背后的机制仍知之甚少。在这里，我们表明，接种在明确界定的条带上的纺锤形细胞群体自发地形成了一种剪切流，其特征取决于条带的宽度。在宽条带上，细胞在向列相中自组织，其指向矢与条带方向成明确角度，并在条带边缘附近形成剪切流。然而，在比临界宽度窄的条带上，细胞与条带方向完美对齐，净流消失。一种流体动力学活性凝胶理论为这些观察结果提供了理解，并将沿条带定向的非流动相和表现出剪切流的倾斜相之间的转变确定为由细胞活性驱动的弗雷德里克兹转变。这种物理理论基于细胞的活性本质，并基于对称性和守恒定律，提供了一种解释体内反平行细胞位移的通用机制。
