Potential anticancer and immunomodulatory effects of TMS magnetic fields

Background: Transcranial magnetic stimulation (TMS) is a non-invasive pain-free medical technology clinically approved for the treatment of drug-resistant depression. Conventional TMS uses non-heating strong (≤4 T) pulsed (≤300 Hz) magnetic fields (MF) to induce electric currents in the cortical neurons and control their activity. However, the effects of the TMS-like MF on non-neuronal cells and artificial systems are almost unknown. We hypothesized that repetitive magnetic stimulation (RMS) by TMS devices can have anticancer and immunomodulatory effects. These effects rely on alternative biophysical (magnetically induced) mechanisms and may help to overcome the problem of cancer drug- and radio-resistance.

Aim: This study explores the potential and feasibility of RMS as an adjuvant/allied treatment in oncology.

Methods: We examined effects of 22 RMS regimes designed de novo on viability and phenotype of tumour and immune cells, including glioblastoma (GBM), pancreatic ductal adenocarcinoma (PDAC), hepatocellular carcinoma (HCC) and colorectal cancer (CRC) cells, microglia (BV2 cell line) and human primary peripheral macrophages. We also tested the effect of PRMS on a drug release from polymer nanoparticles in aqueous environment. A standard TMS device ‘Magstim Rapid2’ with AFC70 coil was applied to the cell cultures spatially configured to correspond to a peak MF of 0.6–0.8 T, 0.25–50 Hz frequency, with sessions of 300 or 600 pulses.

Results: RMS selectively modulated the viability and functional polarisation of immune-stimulated microglia and macrophages in a frequency/intensity-dependent manner and affected the proliferation/viability of cancer cells (cancer type, frequency- and pulse number-dependent up- and down-regulation). The triggering of the drug release from polymer nanoparticles by the 50 Hz/2 min RMS mode was observed.

Conclusions: Our pioneering findings demonstrate the potential of RMS performed by using re-purposed TMS equipment for immunomodulation, cancer treatment and treatment aided with nanomedicines.

Acknowledgements: We thank Sydney Vital (for seed grant) and Medilink Australia (for providing the ‘Magstim’).