Electric fields direct the migration of embryonic stem cells derived motor neurons

Abstract

Spinal cord injury or diseases such as amyotrophic lateral sclerosis can cause the loss of motor neurons and therefore result in muscular paralysis. Stem cells may improve functional recovery after injury by promoting endogenous regeneration, or directly replacing neurons. Effective directional migration of grafted neural cells to reconstruct functional connections is crucial in the process. Steady direct current electric fi elds (EFs) play an important role in the development of the central nervous system. A strong biological effect of EFs is the induction of directional cell migration. In this study, embryonic stem (ES) cells were differentiated using a two-step procedure. The first step was to enhance the neuralization process by adding Noggin and fi broblast growth factor in the cell culture medium. The second step was to induce motor neuron specifi cation by adding retinoic acid and smoothened agonist as cell culture culture supplement. The cells were then treated with brain-derived neurotrophic factor, ciliary neurotrophic factor, glial cell-derived neurotrophic factor and neurotrophin-3 for neurite elongation. The migration of neural precursors from embryoid bodies in EFs was studied. We found that the migration of neural precursors from the embryoid body was toward the cathode pole. We also investigated the EFs-directed migration of dissociated single motor neurons using time-lapse photography.Similarly, single motor neurons migrated to the cathode and the reversal of EFs poles reversed the migration direction of the cells. The directedness and displacement of cathodal migration became more signifi cant when the field strength was increased from 50mV/mm to 100mV/mm. EFs stimulation did not infl uence the cell migration velocity. Our work suggested that EFs may serve as a guidance cue to direct grafted cell migration in vivo.