Static Magnetic Field Exposure Causes Small Cell Cycle Disruptions and Changes in Reactive Oxygen Species Levels in Ionizing Radiation Exposed Human Neuroblastoma Cells

Although static magnetic fields (SMFs) have been reported to induce only minimal biological effects, it has been proposed that they may alter the effects of other agents, such as ionizing radiation. We sham-exposed or exposed human SH-SY5Y neuroblastoma cells to 0.5-, 1.5-, 2.5-, or 3.5-mT SMFs for 24 h either before or after irradiation at 0, 0.4 or 2.0 Gy. After the exposures, cell cycle distribution (subG1 for apoptosis), reactive oxygen species (ROS) levels, caspase-3 activity, and clonogenic survival were assayed. Increase of G0/G1 and decrease of S phase cells was observed in samples exposed to a 3.5-mT SMF after irradiation. The same exposure schedule with a 1.5-mT SMF was associated with an increase of S phase cells, and an increase in ROS levels. Conversely, a decrease in ROS levels was observed in cells exposed to a 2.5-mT SMF before ionizing radiation. No cell cycle changes were observed with SMF exposures before irradiation. Caspase-3 activity or clonogenic survival was not affected by SMF exposures, irrespective of the exposure schedule. In conclusion, small changes in cell cycle distribution and ROS levels were observed in SH-SY5Y cells exposed to SMFs, with more prominent effects observed when SMF exposure was applied after irradiation. Our results suggest that SMF-induced effects show no linear dependency on magnetic flux density below 5 mT. Notably, SMF exposures did not significantly potentiate the effects of ionizing radiation but rather caused an independent additive effect. Bioelectromagnetics. 00:00–00, 2024.