Smartphone generated electrical fields induce axon regrowth within microchannels following injury

Axonal injury is a major pathology of central nervous system injury associated with rapid rupture of axonal projections and resulting in the disconnection from their targets and impaired function. While electrical stimulation can promote axon sprouting in in vitro models, the study of electrical stimulation for axon regrowth following a stretch-induced axonal injury has not been reported. In this work, a simple electrostimulation-on-a-chip was developed to investigate the effect of electrical fields on morphological changes of axons ruptured. A pulse generator application in a smartphone was used to generate the electrical stimulation in microchannels via sterile needles. The results indicated that electrical stimulation promoted axon outgrowth 72% of the injured axons within microchannels. The length of regenerated axons showed a growth rate of 46 µm/day. In comparison, unstimulated controls had 100% axonal degeneration within 3 days and no axon regrowth was observed within 9 days after injury. The modified methods were developed to demonstrate axon regrowth after stretch-induced injury using electrical stimulation in a microchannel culture system. Results encourage an engineering concept of combining soft microchannel scaffold with stimulating electrodes towards developing potential medical devices for traumatic brain and spinal cord injury.