Early exposure of rotating magnetic fields promotes central nervous regeneration in planarian Girardia sinensis.

Magnetic field exposure is an accepted safe and effective modality for nerve injury. However, it is clinically used only as a supplement or salvage therapy at the later stage of treatment. Here, we used a planarian Girardia sinensis decapitated model to investigate beneficial effects of early rotary non-uniform magnetic fields (RMFs) exposure on central nervous regeneration. Our results clearly indicated that magnetic stimulation induced from early RMFs exposure significantly promoted neural regeneration of planarians. This stimulating effect is frequency and intensity dependent. Optimum effects were obtained when decapitated planarians were cultured at 20 °C, starved for 3 days before head-cutting, and treated with 6 Hz 0.02 T RMFs. At early regeneration stage, RMFs exposure eliminated edema around the wound and facilitated subsequent formation of blastema. It also accelerated cell proliferation and recovery of neuron functionality. Early RMFs exposure up-regulated expression of neural regeneration related proteins, EGR4 and Netrin 2, and mature nerve cell marker proteins, NSE and NPY. These results suggest that RMFs therapy produced early and significant benefit in central nervous regeneration, and should be clinically used at the early stage of neural regeneration, with appropriate optimal frequency and intensity.