Electrically mediated neuronal guidance with applied alternating current electric fields

Applied electric fields (EFs) have previously been presented as a potential method of inducing functional recovery after neural trauma. To date, most of this research has focused on the application of a direct current (DC) stimulus to produce the desired EF and induce neuronal growth. We propose that high duty-cycle alternating current (AC) stimulation is capable of inducing similar EFs within the spinal cord and eliciting a neural response with the added benefits of increased field propagation and lower power consumption. Through ex vivo tissue testing of porcine spinal columns and Xenopus laevis cell cultures, 80% duty-cycle AC stimulation was compared to DC stimulation for efficacy in field generation and induction of neurite growth. Results from ex vivo measurement show that AC stimulation is capable of producing EFs of greater magnitudes over an increased distance in the spinal cord than DC stimulation at the same current magnitude. Furthermore, stimulation of Xenopus laevis neuronal cultures with 80% duty-cycle rectangular waves indicated a significant increase in neurite length as compared to non-stimulated controls and cathodal preference, growth that was statistically similar to DC-stimulated cells. These results suggest high duty-cycle stimulation modalities to be applicable and perhaps preferable to DC stimulation in electrically mediated neuronal therapies.