Combined effects of 50 Hz magnetic field and magnetic nanoparticles on the proliferation and apoptosis of PC12 cells

Abstract

Objective: To investigate the bioeffects of extremely low frequency (ELF) magnetic field (MF) (50 Hz, 400 μT) and magnetic nanoparticles (MNPs) via cytotoxicity and apoptosis assays on PC12 cells.

Methods: MNPs modified by SiO₂ (MNP-SiO₂) were characterized by transmission electron microscopy (TEM), dynamic light scattering and hysteresis loop measurement. PC12 cells were administrated with MNP-SiO2 with or without MF exposure for 48 h. Cytotoxicity and apoptosis were evaluated with MTT assay and annexin V-FITC/PI staining, respectively. The morphology and uptake of MNP-SiO₂ were determined by TEM. MF simulation was performed by Ansoft Maxwell based on the finite element method.

Results: MNP-SiO₂ were identified as ~20 nm (diameter) ferromagnetic particles. MNP-SiO₂ reduced cell viability in a dose-dependent manner. MF also reduced cell viability with increasing concentrations of MNP-SiO₂. MNP-SiO₂ alone did not cause apoptosis in PC12 cells; instead, the proportion of apoptotic cells increased significantly under MF exposure and increasing doses of MNP-SiO₂. MNP-SiO₂ could be ingested and then cause a slight change in cell morphology.

Conclusion: Combined exposure of MF and MNP-SiO₂ resulted in remarkable cytotoxicity and increased apoptosis in PC12 cells. The results suggested that MF exposure could strengthen the MF of MNPs, which may enhance the bioeffects of ELF MF.

Keywords: Apoptosis; Cytotoxicity; Extremely low frequency magnetic field; Magnetic nanoparticles; Morphology.