The Influence of Electric Field and Confinement on Cell Motility

The ability of cells to sense and respond to endogenous electric fields is important in processes such as wound healing, development, and nerve regeneration. In cell culture, many epithelial and endothelial cell types respond to an electric field of magnitude similar to endogenous electric fields by moving preferentially either parallel or antiparallel to the field vector, a process known as galvanotaxis. Here we report on the influence of dc electric field and confinement on the motility of fibroblast cells using a chip-based platform. From analysis of cell paths we show that the influence of electric field on motility is much more complex than simply imposing a directional bias towards the cathode or anode. The cell velocity, directedness, as well as the parallel and perpendicular components of the segments along the cell path are dependent on the magnitude of the electric field. Forces in the directions perpendicular and parallel to the electric field are in competition with one another in a voltage-dependent manner, which ultimately govern the trajectories of the cells in the presence of an electric field. To further investigate the effects of cell reorientation in the presence of a field, cells are confined within microchannels to physically prohibit the alignment seen in 2D environment. Interestingly, we found that confinement results in an increase in cell velocity both in the absence and presence of an electric field compared to migration in 2D.细胞感知并响应内源性电场的能力，在伤口愈合、发育及神经再生等生理过程中具有关键作用。在细胞培养体系中，多种上皮细胞与内皮细胞可对强度与内源性电场相近的电场作出响应，优先沿电场矢量方向同向或反向迁移，这一过程被称为趋电性（galvanotaxis）。本研究借助基于芯片的实验平台，探究了直流电场（DC electric field）与空间约束对成纤维细胞运动能力的影响。通过对细胞迁移路径的分析，我们发现电场对细胞运动的调控远比仅使细胞向阴极或阳极产生定向偏移更为复杂：细胞运动速度、迁移定向性，以及细胞路径各片段的平行与垂直电场分量，均随电场强度发生变化。垂直与平行于电场方向的细胞受力以电压依赖的方式相互竞争，这一过程最终决定了电场作用下细胞的运动轨迹。为进一步探究电场存在时细胞重定向的调控效应，我们将细胞约束于微通道内，以物理方式阻断二维培养环境中常见的细胞定向排列现象。有趣的是，我们发现相较于二维培养环境中的迁移行为，无论是否施加电场，空间约束均可提升细胞的运动速度。