Study type: Medical/biological study (experimental study)

Differential effects of high and low strength magnetic fields on mouse embryonic development and vasculogenesis of embryonic stem cells. med./bio.

Published in: Reprod Toxicol 2016; 65: 46-58

Aim of study (acc. to author)

The effects of prenatal exposure of mice to a static or 50 Hz magnetic field on the embryonic development should be investigated.

Background/further details

The study comprised an in vivo and an in vitro part. For the in vivo part, pregnant mice were divided into the following groups (n=10 for each method and time of investigation, total number unclear): exposure to a 1) 1 mT 50 Hz magnetic field, 2) 1 mT static magnetic field, 3) 10 mT 50 Hz magnetic field, 4) 10 mT static magnetic field and 5) sham exposure. Embryos were collected and examined after 5, 8, 12 and 20 days of exposure.
In addition, 50 non-pregnant mice were exposed to the same fields (n=10 each) but no detailed results were shown.
For the in vitro part, embryoid bodies, aggregations of pluripotent mouse embryonic stem cells, were used as models for embryonic development and were exposed to the same fields: 6) 1 mT 50 Hz magnetic field, 7) 1 mT static magnetic field, 8) 10 mT 50 Hz magnetic field, 9) 10 mT static magnetic field and 10) sham exposure.
In the in vitro tests, cells were also treated with p38 MAPK, JNK and ERK-1/2 inhibitors and free radical scavengers to examine the signal pathways.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: 8 hours/day for up to 20 days during gestation
Exposure 2:
Exposure duration: 8 hours/day for up to 20 days during gestation
Exposure 3: 50 Hz
Exposure duration: 8 hours/day for up to 20 days during gestation
Exposure 4:
Exposure duration: 8 hours/day for up to 20 days during gestation
Exposure 5: 50 Hz
Exposure duration: 8 hours/day from 2 to 8 during differentiation
Exposure 6:
Exposure duration: 8 hours/day from 2 to 8 during differentiation
Exposure 7: 50 Hz
Exposure duration: 8 hours/day from 2 to 8 during differentiation
Exposure 8:
Exposure duration: 8 hours/day from 2 to 8 during differentiation

Exposure 1

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration 8 hours/day for up to 20 days during gestation
Additional info in vivo
Exposure setup
Exposure source
Chamber high enough cages made of dielectric, transparent plastic
Setup ten mice were placed in 2 cages (5 mice per cage) in homogeneous field; coils were wound on tubes from polyvinylchloride (PVC), which shielded against emission of electric fields; temperature changes in exposure chamber was 1°C ± 0.5°C
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1 mT - measured - -

Exposure 2

Main characteristics
Frequency
Type
Exposure duration 8 hours/day for up to 20 days during gestation
Additional info in vivo
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1 mT - measured - -

Exposure 3

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration 8 hours/day for up to 20 days during gestation
Additional info in vivo
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 10 mT - measured - -

Exposure 4

Main characteristics
Frequency
Type
Exposure duration 8 hours/day for up to 20 days during gestation
Additional info in vivo
Exposure setup
Exposure source
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 10 mT - measured - -

Exposure 5

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration 8 hours/day from 2 to 8 during differentiation
Additional info in vitro
Exposure setup
Exposure source
Setup differences from exposure 1: embryoid bodies in petri dishes; 5% CO2, 37°C
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1 mT - measured - -

Exposure 6

Main characteristics
Frequency
Type
Exposure duration 8 hours/day from 2 to 8 during differentiation
Additional info in vitro
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 1 mT - measured - -

Exposure 7

Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration 8 hours/day from 2 to 8 during differentiation
Additional info in vitro
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 10 mT - measured - -

Exposure 8

Main characteristics
Frequency
Type
Exposure duration 8 hours/day from 2 to 8 during differentiation
Additional info in vitro
Exposure setup
Exposure source
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 10 mT - measured - -

Reference articles

  • Bekhite MM et al. (2010): Static electromagnetic fields induce vasculogenesis and chondro-osteogenesis of mouse embryonic stem cells by reactive oxygen species-mediated up-regulation of vascular endothelial growth factor.

Exposed system:

Methods Endpoint/measurement parameters/methodology

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

Main outcome of study (acc. to author)

In the 10 mT static and 50 Hz magnetic field groups (groups 3 and 4), a significantly increased number of resorbed and dead fetuses, pronounced histological alterations, reduced blood vessel formation and a significantly reduced VEGF protein expression in all organs compared to the sham exposure group were found. Additionally, a significantly reduced crown-rump length and body weight of fetuses were found in group 4 compared to the sham exposure group after 20 days. This was not observed in 1 mT magnetic fields (groups 1 and 2) but instead, VEGF expression in the ovary was significantly increased compared to the sham exposure group.
In embryoid bodies, exposure to 10 mT static or 50 Hz fields (groups 8 and 9) significantly increased reactive oxygen species (6-fold increase) and apoptosis, while significantly decreasing the blood vessel formation and VEGF expression compared to the sham exposure group.
In groups 6 and 7 (exposure of embryoid bodies to 1 mT static or 50 Hz fields), reactive oxygen species were also significantly increased compared to the sham exposure group but only a 2-fold increase was measured, and the expression of VEGF was significantly increased.
Treatment with inhibitors showed that reactive oxygen species were involved in the magnetic field-induced signal transduction, which led to activation of VEGF.
The authors conclude that prenatal exposure of mice to high (10 mT) static or 50 Hz magnetic field might have adverse effects on the embryonic development. VEGF is possibly an important mediator in these effects.

Study character:

Study funded by

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