Electrical fields, nerve growth and nerve regeneration

Abstract

The presence of voltage gradients within developing and damaged tissues led to the notion that the resultant electrical fields provide instructional cues to cells. Field effects on avian and amphibian neurones in vitro include increased differentiation, turning of neurites towards the cathode, increased rate of growth towards the cathode, resorption of anodefacing neurites, increased branching and increased filopodial activity. Electric fields enhance regeneration of damaged PNS and CNS neurones in animals as diverse as lampreys, frogs, rats and guinea‐pigs, but the mechanisms by which fields produce their effects are not understood. Further examination of the interaction of fields with intracellular elements, such as the cytoskeleton and second messenger systems, may offer some insight.

Electrical Stimulation of Schwann Cells Promotes Sustained Increases in Neurite Outgrowth

“…The custom electrical stimulation culture chambers utilized in this work are described in Koppes et al 38 based on previously described chambers used in McCaig and Rajnicek, 21 Pedrotty et al 44 In brief, a nonconductive Sylgard 184 poly (dimethylsiloxane) base and curing agent (PDMS; Dow Corning) were mixed (10:1 wt./wt.) and allowed to cure in rectangular polystyrene plates (Thermo Fisher Scientific).…”

“…200 mV/mm represents the upper limits of previously reported physiologic field strengths measured during development and wound healing. [21][22][23][24][25][26][27][28][29]37 Based on this evidence, the magnitude should be maintained at < 200 mV/ mm, and/or duration of stimulus should be < 8 h for viable Schwann cells (Supplementary Fig. S2).…”

“…9,[19][20][21] In vivo, both neurons and non-neuronal cells are exposed to a naturally occurring endogenous current (biophysical cue) created by the epithelium during development and postnatally after injury. 21,22 In the developing embryonic chick, electrical cues are known to be instructive to cell migration and tissue formation, and if disrupted, they can lead to abnormal limb bud formation. 22 Furthermore, if sensitivity to this cue is retained postnatally, electrical stimulation may serve to enhance nerve repair.…”

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Endogenous electric fields are instructive during embryogenesis by acting to direct cell migration, and postnatally, they can promote axonal growth after injury (McCaig 1991, Al-Majed 2000. However, the mechanisms for these changes are not well understood.

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Controlling Cell Behavior Electrically: Current Views and Future Potential

“…The notion that nerve growth could be directed using electrical signals is an old one, and the historical background is outlined fully elsewhere (120,129). Briefly, the earliest attempt to test this experimentally was made by Ingvar in 1920 (86), shortly after the discovery of the tissue culture technique.…”