Different macrophage phenotypes play important roles in diverse biological processes and diseases. In this study, we have characterized the dielectrophoretic responses of human monocytes and macrophage phenotypes: nonactivated (M0), pro-inflammatory (M1), and pro-healing (M2a). Dielectrophoretic responses of cells change as a function of frequency of the applied electric field. We measured the crossover frequency at which cells transition from negative to positive dielectrophoresis (DEP) or vice versa using interdigitated electrodes. For these characterization experiments, we also developed a new low-conductivity media formulation that retained 100% of the initial viability for 1 h. Human THP1 monocytes showed a distinguishable DEP response from mature macrophages. M1 macrophages also showed a distinct DEP response compared to M0 and M2a macrophages. No clear distinction could be drawn between M0 and M2a. The median values of the crossover frequencies of monocytes, M0, M1, and M2a were 38, 21, 11, and 23 kHz, respectively. Membrane capacitances of these cells were calculated consequently, and the values were 0.0111, 0.0128, 0.0244, and 0.0117 F/m² for monocytes, M0, M1, and M2a, respectively. These results show how bioelectric properties are influenced by changes in macrophage phenotype.

中文翻译：

---

巨噬细胞表型的介电泳表征

不同的巨噬细胞表型在不同的生物过程和疾病中发挥重要作用。在这项研究中，我们描述了人类单核细胞和巨噬细胞表型的介电泳反应：非活化 (M0)、促炎 (M1) 和促愈合 (M2a)。细胞的介电泳响应随所施加电场的频率而变化。我们使用叉指电极测量了细胞从负介电泳 (DEP) 转变为正介电泳 (DEP) 或相反的交叉频率。对于这些表征实验，我们还开发了一种新的低电导率培养基配方，可在 1 小时内保留 100% 的初始活力。人 THP1 单核细胞显示出与成熟巨噬细胞不同的 DEP 反应。与 M0 和 M2a 巨噬细胞相比，M1 巨噬细胞也表现出明显的 DEP 反应。M0 和 M2a 之间没有明确的区别。单核细胞、M0、M1 和 M2a 的交叉频率的中值分别为 38、21、11 和 23 kHz。随后计算了这些细胞的膜电容，其值为 0.0111、0.0128、0.0244 和 0.0117 F/m²对于单核细胞，分别为 M0、M1 和 M2a。这些结果表明生物电特性如何受巨噬细胞表型变化的影响。