Directed and enhanced neurite growth with pulsed magnetic field stimulation

Abstract

Pulsed magnetic field (PMF) stimulation was applied to mammalian neurons in vitro to influence axonal growth and to determine whether induced current would direct and enhance neurite growth in the direction of the current. Two coils were constructed from individual sheets of copper folded into a square coil. Each coil was placed in a separate water‐jacketed incubator. One was energized by a waveform generator driving a power amplifier, the other was not energized. Whole dorsal root ganglia (DRG) explant cultures from 15‐day Sprague–Dawley rat embryos were established in supplemented media plus nerve growth factor (NGF) at concentrations of 0–100 ng/mL on a collagen–laminin substrate. Dishes were placed at the center of the top and bottom of both coils, so that the DRG were adjacent to the current flowing in the coil. After an initial 12 h allowing DRG attachment to the substrate floor, one coil was energized for 18 h, followed by a postexposure period of 18 h. Total incubation time was 48 h for all DRG cultures. At termination, DRG were histochemically stained for visualization and quantitative analysis of neurite outgrowth. Direction and length of neurite outgrowth were recorded with respect to direction of the current. PMF exposed DRG exhibited asymmetrical growth parallel to the current direction with concomitant enhancement of neurite length. DRG cultures not PMF exposed had a characteristic radial pattern of neurite outgrowth. These results suggest that PMF may offer a noninvasive mechanism to direct and promote nerve regeneration. Bioelectromagnetics 21:272–286, 2000. © 2000 Wiley‐Liss, Inc.

The application of magnets directs the orientation of neurite outgrowth in cultured human neuronal cells

“…Although changing magnetic force has been reported to increase the formation of neuronal processes (Blackman et al, 1993a;Macias et al, 2000) and enhance the release of neurotransmitters (DruckerColin et al, 1994), there were also contradictory evidences that sinusoidal magnetic force inhibits the production of neuronal processes (Blackman et al, 1993b;McFarlane et al, 2000). There is little information regarding the application of perpetual magnets to direct the orientation of neuronal processes during formation, although it has been known that neuronal processes can be directed by a pulsed magnetic field which generates electric currents (Macias et al, 2000). Our finding showed that simple magnets also direct the orientation of neural processes in cultured neuronal cells.…”

“…Electrical currents can generate magnetic force in the perpendicular direction, and they interact each others (Petridou et al, 2006;Schnabel and Struijk, 1999). Although the directions of neuronal processes have been known to be influenced by a pulsed magnetic field (Macias et al, 2000), it is still unknown whether static magnetic fields directly affect the neurite properties of neurons.…”

Exposure to Pulsed Magnetic Fields Enhances Motor Recovery in Cats After Spinal Cord Injury

“…6,8,21,24,34,41,43,58,64 Most of these models allow the weight to drop onto an impounder resting on the exposed dura mater and provide a transducer between the weight mass and the impounder to record the dynamic parameters. The NYU device directly drops the mass onto the dura mater.…”

“…23,34 Specifically designed Helmholtz coils were used, 5 and a study using an animal model to investigate the bioeffects of PMF stimulation after acute SCI was designed. The histopathology, recovery of locomotor function, and changes in somatosensory-evoked potentials (SEPs) throughout the recovery period were evaluated.…”

50 Hz alternating extremely low frequency magnetic fields affect excitability, firing and action potential shape through interaction with ionic channels in snail neurones

“…A substantial body of evidence has, over the last decade, demonstrated the influence of the electromagnetic fields on biological systems (Azanza and Moral 1996;Calvo and Azanza 1999;Cridland 1999;Morgado-Valle et al 1998;Macias et al 2000;Rosen 2003a, b). At present the mechanisms by which 50 Hz ELF magnetic fields interact at the cellular level is poorly documented.…”