Feng Z, Wagatsuma Y, Kobayashi S, Kosawada T, Sato D, Nakamura T, Kitajima T, Umezu M
Annu Int Conf IEEE Eng Med Biol Soc. 2013;2013:6232-5. doi: 10.1109/EMBC.2013.6610977.
Based on the experimental data of the contraction ratio of fibroblast-collagen gels with different initial collagen concentrations and cell numbers, we analyzed the traction force exerted by individual cells through a novel elementary structural model. We postulate that the mechanical mechanism of the gel contraction is mainly because that populated cells apply traction force to some of the surrounding collagen fibrils with such proper length potential to be pulled straight so as to be able to sustain the traction force; this traction induce the cells moving closely to each other and consequently compact the fibrillar network; the bending force of the fibrils in turn resists the movement. By employing fiber packing theory for random fibrillar networks and network alteration theory, the bending force of collagen fibrils was deduced. The traction force exerted by individual fibroblasts in the gels was balanced by the bending force and the resistance from interstitial fluid since inertial force can be neglected. The maximum traction force per cell under free floating condition is in the range of 0.27-9.02 nN depending on the initial collagen concentration and populated cell number. The most important outcome of this study is that the traction force of individual cells dynamically varies under different gel conditions, whereas the adhesion force between cell and individual fibrils is relatively converging and stable.
基于不同初始胶原蛋白浓度和细胞数量的成纤维细胞-胶原蛋白凝胶收缩率的实验数据，我们通过一种新颖的基本结构模型分析了单个细胞施加的牵引力。我们推测，凝胶收缩的力学机制主要是因为聚集的细胞对周围一些具有适当长度潜力的胶原纤维施加牵引力，使其能够被拉直从而承受牵引力；这种牵引力促使细胞彼此靠近，进而压实纤维网络；纤维的弯曲力反过来抵抗这种运动。通过应用随机纤维网络的纤维堆积理论和网络改变理论，推导出了胶原纤维的弯曲力。由于惯性力可忽略不计，凝胶中单个成纤维细胞施加的牵引力由弯曲力和细胞外液的阻力平衡。在自由漂浮条件下，每个细胞的最大牵引力在0.27 - 9.02 nN范围内，这取决于初始胶原蛋白浓度和聚集的细胞数量。这项研究最重要的结果是，在不同的凝胶条件下，单个细胞的牵引力动态变化，而细胞与单个纤维之间的粘附力相对收敛且稳定。
