Transspinal direct current stimulation modulates migration and proliferation of adult newly born spinal cells in mice

Abstract

Direct current electrical fields have been shown to be a major factor in the regulation of cell proliferation, differentiation, migration, and survival, as well as in the maturation of dividing cells during development. During adulthood, spinal cord cells are continuously produced in both animals and humans, and they hold great potential for neural restoration following spinal cord injury. While the effects of direct current electrical fields on adult-born spinal cells cultured ex vivo have recently been reported, the effects of direct current electrical fields on adult-born spinal cells in vivo have not been characterized. Here, we provide convincing findings that a therapeutic form of transspinal direct current stimulation (tsDCS) affects the migration and proliferation of adult-born spinal cells in mice. Specifically, cathodal tsDCS attracted the adult-born spinal cells, while anodal tsDCS repulsed them. In addition, both tsDCS polarities caused a significant increase in cell number. Regarding the potential mechanisms involved, both cathodal and anodal tsDCS caused significant increases in expression of brain-derived neurotrophic factor, while expression of nerve growth factor increased and decreased, respectively. In the spinal cord, both anodal and cathodal tsDCS increased blood flow. Since blood flow and angiogenesis are associated with the proliferation of neural stem cells, increased blood flow may represent a major factor in the modulation of newly born spinal cells by tsDCS. Consequently, we propose that the method and novel findings presented in the current study have the potential to facilitate cellular, molecular, and/or bioengineering strategies to repair injured spinal cords. NEW & NOTEWORTHY Our results indicate that transspinal direct current stimulation (tsDCS) affects the migratory pattern and proliferation of adult newly born spinal cells, a cell population which has been implicated in learning and memory. In addition, our results suggest a potential mechanism of action regarding the functional effects of applying direct current. Thus tsDCS may represent a novel method by which to manipulate the migration and cell number of adult newly born cells and restore functions following brain or spinal cord injury.