Institute of Applied Physics, University of Tübingen, Auf der Morgenstelle 10, 72076 Tübingen, Germany.
Soft Matter. 2019 Feb 20;15(8):1721-1729. doi: 10.1039/c8sm01585f.
Living cells exhibit a complex mechanical behavior, whose underlying mechanisms are still largely unknown. Emerging from the molecular structure and dynamics of the cytoskeleton, the mechanical behavior comprises "passive" viscoelastic material properties and "active" contractile prestress. To directly investigate the connection between these quantities at the single-cell level, we here present the combination of atomic force microscopy (AFM) with traction force microscopy (TFM). With this combination, we simultaneously measure viscoelastic material parameters (stiffness, fluidity) and contractile prestress of adherent fibroblast and epithelial cells. Although stiffness, fluidity, and contractile prestress greatly vary within a cell population, they are highly correlated: stiffer cells have a lower fluidity and a larger prestress than softer cells. We show that viscoelastic material properties and contractile prestress are both governed by the activity of the actomyosin machinery. Our results underline the connection between a cell's viscoelastic material properties and its contractile prestress and their importance in cell mechanics.
活细胞表现出复杂的机械行为，但其潜在机制在很大程度上尚不清楚。这种机械行为源自细胞骨架的分子结构和动力学，包括“被动”粘弹性材料特性和“主动”收缩预应力。为了在单细胞水平上直接研究这些量之间的联系，我们在这里将原子力显微镜（AFM）与牵引力显微镜（TFM）相结合。通过这种组合，我们可以同时测量贴壁成纤维细胞和上皮细胞的粘弹性材料参数（硬度、流动性）和收缩预应力。尽管细胞群体中的硬度、流动性和收缩预应力有很大差异，但它们高度相关：较硬的细胞比较软的细胞流动性更低，预应力更大。我们表明，粘弹性材料特性和收缩预应力都受肌动球蛋白机制的活性控制。我们的结果强调了细胞粘弹性材料特性与其收缩预应力之间的联系及其在细胞力学中的重要性。
