Study type: Medical/biological study (experimental study)

Effects of Electromagnetic Field (PEMF) Exposure at Different Frequency and Duration on the Peripheral Nerve Regeneration: in Vitro and in Vivo Study. med./bio.

Published in: Int J Neurosci 2016; 126 (8): 739-748

Aim of study (acc. to author)

The effects of exposure to pulsed extremely low frequency magnetic fields of different frequencies and durations on the peripheral nerve regeneration in rats and cell proliferation in Schwann cells should be investigated.

Background/further details

The study comprised in vitro tests with immortalized Schwann cells of rats and in vivo tests with rats.
For the in vitro tests, cells were divided into 5 groups: exposure to a pulsed magnetic field of 1) 50 Hz for 1 hour/day, 2) 50 Hz for 12 hours/day, 3) 150 Hz for 1 hour/day, 4) 150 Hz for 12 hours/day and 5) control group.
For the in vivo tests, chin nerves of rats were crush injured between lip area and mental foramen (except in the sham group) and the animals were divided into 6 groups (n=10 each): exposure to a pulsed magnetic field of 6) 50 Hz for 1 hour/day, 7) 50 Hz for 12 hours/day, 8) 150 Hz for 1 hour/day, 9), 150 Hz for 12 hours/day, 10) control group, 11) sham group without injury and magnetic field exposure.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: 1 hour/day for up to 3 weeks
Exposure 2: 50 Hz
Exposure duration: 12 hours/day for up to 3 weeks
Exposure 3: 150 Hz
Exposure duration: 1 hour/day for up to 3 weeks
Exposure 4: 150 Hz
Exposure duration: 12 hours/day for up to 3 weeks
Exposure 5: 50 Hz
Exposure duration: 1 hour/day for 3 weeks
Exposure 6: 50 Hz
Exposure duration: 12 hours/day for 3 weeks
Exposure 7: 150 Hz
Exposure duration: 1 hour/day for 3 weeks
Exposure 8: 150 Hz
Exposure duration: 12 hours/day for 3 weeks

General information

no details given on pulse repetition rate and pulse width

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration 1 hour/day for up to 3 weeks
Additional info in vitro exposure
Exposure setup
Exposure source
Chamber coils in incubator
Setup two identical Helmholtz coils of 30 cm diameter, 7 cm width and 15 cm distance; vertical field
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1 mT - - - -

Exposure 2

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration 12 hours/day for up to 3 weeks
Additional info in vitro exposure
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1 mT - - - -

Exposure 3

Main characteristics
Frequency 150 Hz
Type
Waveform
Exposure duration 1 hour/day for up to 3 weeks
Additional info in vitro exposure
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1 mT - - - -

Exposure 4

Main characteristics
Frequency 150 Hz
Type
Waveform
Exposure duration 12 hours/day for up to 3 weeks
Additional info in vitro exposure
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1 mT - - - -

Exposure 5

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration 1 hour/day for 3 weeks
Additional info in vivo exposure
Exposure setup
Exposure source
Setup a pair of Helmholtz coils of 60 cm diameter and a distance of 30 cm
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1 mT - - - -

Exposure 6

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration 12 hours/day for 3 weeks
Additional info in vivo exposure
Exposure setup
Exposure source
  • same setup as in E5
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1 mT - - - -

Exposure 7

Main characteristics
Frequency 150 Hz
Type
Waveform
Exposure duration 1 hour/day for 3 weeks
Additional info in vivo exposure
Exposure setup
Exposure source
  • same steup as in E5
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1 mT - - - -

Exposure 8

Main characteristics
Frequency 150 Hz
Type
Waveform
Exposure duration 12 hours/day for 3 weeks
Additional info in vivo exposure
Exposure setup
Exposure source
  • same setup as in E5
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1 mT - - - -

Reference articles

  • Kim YT et al. (2015): Co-treatment Effect of Pulsed Electromagnetic Field (PEMF) with Human Dental Pulp Stromal Cells and FK506 on the Regeneration of Crush Injured Rat Sciatic Nerve.

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Investigated organ system:
Time of investigation:
  • before exposure
  • during exposure
  • after exposure

Main outcome of study (acc. to author)

In the in vitro tests, group 1 (50 Hz exposure for 1 hour/day) showed a significantly increased cell proliferation after 4-7 days and a significantly increased gene expression of S100 and BDNF after 1-3 weeks compared to the control group.
In the in vivo tests, the difference score was significantly decreased after 2 and 3 weeks and the gap score was significantly decreased after 3 weeks in group 6 (50 Hz exposure for 1 hour/day) compared to the control group (group 10), indicating an improved sensory function.
A significantly increased number of axons and retrograde labeled neurons was found in all exposure groups (groups 6-9) compared to the control group, with the highest values found in group 6.
The authors conclude that exposure to a pulsed 50 Hz magnetic field for 1 hour/day might be beneficial in peripheral nerve regeneration via increase in cell proliferation and BDNF and S100 gene expression. Hence, these could also be suitable exposure conditions in clinical applications.

Study character:

Study funded by

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