Pulsed electromagnetic fields stimulate nerve regeneration in vitro and in vivo.

The influence of non-invasive, low level, pulsed electromagnetic fields (PEMF) on regeneration was tested on in vitro and in vivo models. Cultures of dorsal root ganglia were exposed to 2 Hz PEMF, amplitude of 0.05 mTesla while rats after a 'crush' lesion of sciatic nerves were exposed to 2 Hz PEMF, amplitude of 0.3 mTesla. In in vitro experiments, relative to controls, cultures treated with PEMF exhibited a significant increase in neurite outgrowth with dense labeling of neurons and neurites on autoradiographs after incorporation of [3H]proline into new proteins. In vivo exposure of rats to PEMF for 3, 4 or 6 days after lesioning produced a 22% increase in the regeneration rate relative to controls with no effect on the initial delay period. When rats were exposed to PEMF before lesioning without further treatment, the same degree of stimulation of axonal sprouting was obtained. Reduction of the amplitude from 0.3 mTesla to 0.06 mTesla eliminated this pre-exposure response. Alterations in the distribution of new proteins synthesized 2 weeks after PEMF treatment provide additional evidence for its influence at the whole body and cellular levels.