Proof of Concept of an ELF Magnetic Field Exposure System with Biphasic Magnetic Pulses: Effects on Human Dermal Fibroblast Proliferation

The aim of this work was to validate the usefulness of an Extremely Low Frequency (ELF) magnetic field exposure system with a magnetotherapy device of common use in clinical practice that generates Biphasic Magnetic Pulses (BMP), in order to study the effects of the BMP on the proliferation of Human Dermal Fibroblasts (HDF). In that regard, HDF were exposed 2h in the morning and 2h in the afternoon for 2 days to BMP of 1.41mT peak value at 5, 10, 25Hz continuous and 50Hz intermittent (2s on/ 1.5s off). MTT assay was performed to assess proliferation. The 10Hz BMP showed a significant decrease in proliferation of 6.6% (p = 0.001) with respect to controls, but no significant changes in proliferation were seen with the other BMP. In order to analyze whether these results could be related to the exposure protocol, a 50Hz power line intermittent signal (1s on/ 1s off) was generated and tested but exposure time was increased to 48h to cover the complete cells doubling time. A significant increase in proliferation of 9% (p < 0.001) was found in this case. The results validate the in vitro exposure system for its use with the BMP. Though the MTT proliferation assay alone is not enough to make definitive claims, the results might indicate that exposure time plays a key role in the outcome of the experiments. Therefore, special attention should be paid to the exposure time on in vitro protocols and how they relate to in vivo experiments and current treatments.