An electrical model with microtubules, impedance measurements and COMSOL simulations for single MDA-MB-231 cells under extremely low frequency electromagnetic fields

This paper presents an electrical equivalent model with microtubules (MTs) for use in analyzing the division process of human breast cancer cells (MDA-MB-231). A three-dimensional cell capture and sensing array electrode (3D ECCSA) and an extremely-low-frequency electromagnetic field (ELF-EMF) were integrated for the real-time monitoring of human breast cancer cells for 12 h. The relationship between the cellular processes (cell-spreading stage, cell mitosis stage, and cell division stage) and the ELF-EMF can be analyzed using the electrical equivalent model, the impedance measurements in the experiment, and COMSOL simulations. This was the first time that a circuit model combined with MTs was used to analyze cancer cells under an ELF-EMF. MT impedance contains MT–cell membrane contact resistance(R_Mct), MT resistance (R_MT), and MT capacitance (C_MT). At the cell-spreading stage, the ELF-EMF-reduced assembly of the MTs impedes the cell spread, which leads to lower impedance variation. At the cell mitosis stage, the MT volume variation in the ELF-EMF group decreases faster than that in the control group, which indicates that the ELF-EMF influences the assembly of the MTs. In addition, the ELF-EMF impedes the assembly of the MTs between the mitotic spindles, and then the cells prolong the cell mitosis period, which can be analyzed through the cell impedance and our model. At cell division, the impedance increases because two daughter cells block more current. Our study showed that the novel model with MTs and a 3D ECCSA could analyze the cell mitosis process under an ELF-EMF.