Physics Department, James Franck Institute and Institute for Biophysical Dynamics, University of Chicago, Chicago, IL, USA.
J Phys Condens Matter. 2010 May 19;22(19):194104. doi: 10.1088/0953-8984/22/19/194104.
To understand how adherent cells regulate traction forces on their surrounding extracellular matrix (ECM), quantitative techniques are needed to measure forces at the cell-ECM interface. Microcontact printing is used to create a substrate of 1 μm diameter circles of ECM ligand to experimentally study the reconstruction of traction stresses at constrained, point-like focal adhesions. Traction reconstruction with point forces (TRPF) and Fourier transform traction cytometry (FTTC) are used to calculate the traction forces and stress field, respectively, at isolated adhesions. We find that the stress field calculated with FTTC peaks near the center of individual adhesions but propagates several microns beyond the adhesion location. We find the optimal set of FTTC parameters that yield the highest stress magnitude, minimizing information lost from over-smoothing and sampling of the displacement or stress field. A positive correlation between the TRPF and FTTC measurements exists, but integrating the FTTC stress field over the adhesion area yields only a small fraction of the force calculated by TRPF. An effective area similar to that defined by the width of the stress distribution measured with FTTC is required to reconcile these measurements. These measurements set bounds on the spatial resolution and precision of FTTC measurements on micron-sized adhesions.
为了了解贴壁细胞如何调节其周围细胞外基质（ECM）上的牵引力，需要定量技术来测量细胞-ECM 界面上的力。微接触印刷用于创建 ECM 配体的 1μm 直径圆圈的基底，以实验研究约束点状黏附点处牵引力的重建。使用点力牵引力重建（TRPF）和傅里叶变换牵引力细胞术（FTTC）分别计算孤立黏附点处的牵引力和应力场。我们发现，FTTC 计算出的应力场在单个黏附点的中心附近达到峰值，但在黏附位置之外传播了几个微米。我们找到了一组最佳的 FTTC 参数，这些参数产生了最大的应力幅度，同时最小化了由于过度平滑和对位移或应力场的采样而导致的信息丢失。TRPF 和 FTTC 测量之间存在正相关关系，但将 FTTC 应力场积分到黏附区域仅产生 TRPF 计算出的力的一小部分。需要类似于 FTTC 测量的应力分布宽度定义的有效区域来协调这些测量。这些测量为微米大小的黏附点上的 FTTC 测量的空间分辨率和精度设定了界限。
