Study type: Medical/biological study (experimental study)

High frequency electromagnetic fields (GSM signals) affect gene expression levels in tumor suppressor p53-deficient embryonic stem cells. med./bio.

Published in: Bioelectromagnetics 2004; 25 (4): 296-307

Aim of study (acc. to author)

The effects of electromagnetic field exposure were comparatively analyzed in pluripotent embryonic stem cells and embryonic carcinoma cells, including embryonic stem cells deficient for p53, a tumor suppressor protein, to determine the cellular susceptibility to develop spontaneous tumors.

Background/further details

Two GSM modulation schemes (GSM-217 and GSM-Talk), which generate temporal changes between GSM-Basic (active during talking phases) and GSM-DTX (active during listening phases thus simulating a typical conversation), were applied to the cells.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 1.71 GHz
Modulation type: pulsed
Exposure duration: intermittent, 5/30 min On/Off cycles for 6 or 48 hours
  • SAR: 1.5 W/kg average over time
  • SAR: 12 W/kg cf. remarks (slot SAR)
Exposure 2: 1.71 GHz
Modulation type: pulsed
Exposure duration: intermittent, 5/30 min On/Off cycles for 72 hours
  • SAR: 2 W/kg average over time
  • SAR: 16 W/kg cf. remarks (slot SAR)
Exposure 3: 1.71 GHz
Modulation type: pulsed
Exposure duration: intermittent, 5/30 min On/Off cycles for 22 or 40 hours
  • SAR: 2 W/kg average over time
  • SAR: 16 W/kg cf. remarks (slot SAR)
Exposure 4: 1.71 GHz
Modulation type: pulsed
Exposure duration: intermittent, 5/30 min On/Off cycles for 6 or 48 hours
  • SAR: 0.4 W/kg average over time
  • SAR: 8 W/kg cf. remarks (slot SAR)

Exposure 1

Main characteristics
Frequency 1.71 GHz
Type
Charakteristic
  • guided field
Exposure duration intermittent, 5/30 min On/Off cycles for 6 or 48 hours
Modulation
Modulation type pulsed
Pulse width 0.576 ms
Duty cycle 12.5 %
Repetition frequency 217 Hz
Pulse type rectangular
Additional info

GSM-217 signals

Exposure setup
Exposure source
Chamber Four R14 waveguides (two for EMF exposure and two for sham exposure) enclosed in an incubator (5% CO2, 37 °C) were used.
Setup Petri dishes (60 mm) were positioned in the H field maximum of a standing wave and exposed in E polarization.
Additional info Cells were EMF or sham exposed during differentiation in hanging drops.
Parameters
Measurand Value Type Method Mass Remarks
SAR 1.5 W/kg average over time measured and calculated - -
SAR 12 W/kg cf. remarks measured and calculated - slot SAR

Exposure 2

Main characteristics
Frequency 1.71 GHz
Type
Charakteristic
  • guided field
Exposure duration intermittent, 5/30 min On/Off cycles for 72 hours
Modulation
Modulation type pulsed
Pulse width 0.576 ms
Duty cycle 12.5 %
Repetition frequency 217 Hz
Pulse type rectangular
Additional info

GSM-217 signals

Exposure setup
Exposure source
Additional info Cells were EMF or sham exposed during cultivation in suspension.
Parameters
Measurand Value Type Method Mass Remarks
SAR 2 W/kg average over time measured and calculated - -
SAR 16 W/kg cf. remarks measured and calculated - slot SAR

Exposure 3

Main characteristics
Frequency 1.71 GHz
Type
Charakteristic
  • guided field
Exposure duration intermittent, 5/30 min On/Off cycles for 22 or 40 hours
Modulation
Modulation type pulsed
Pulse width 0.576 ms
Duty cycle 12.5 %
Repetition frequency 217 Hz
Pulse type rectangular
Additional info

GSM-217 signals

Exposure setup
Exposure source
Additional info Cells were EMF or sham exposed during cultivation in monolayer.
Parameters
Measurand Value Type Method Mass Remarks
SAR 2 W/kg average over time measured and calculated - -
SAR 16 W/kg cf. remarks measured and calculated - slot SAR

Exposure 4

Main characteristics
Frequency 1.71 GHz
Type
Charakteristic
  • guided field
Exposure duration intermittent, 5/30 min On/Off cycles for 6 or 48 hours
Modulation
Modulation type pulsed
Pulse width 0.576 ms
Duty cycle 12.5 %
Repetition frequency 217 Hz
Pulse type rectangular
Additional info

GSM-Talk signals were applied consisting of 33% GSM-Basic and 67% GSM-DTX (discontinuous transmission mode). GSM-Basic is similar to GSM-217 signal , except that every 26th frame is idle. The frame structure of the DTX signal results in 2, 8 and 217 Hz components.

Exposure setup
Exposure source
Additional info Cells were EMF or sham exposed during differentiation in hanging drops.
Parameters
Measurand Value Type Method Mass Remarks
SAR 0.4 W/kg average over time measured and calculated - -
SAR 8 W/kg cf. remarks measured and calculated - slot SAR

Reference articles

  • Schönborn F et al. (2000): Design, optimization, realization, and analysis of an in vitro system for the exposure of embryonic stem cells at 1.71 GHz.

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

GSM-217 electromagnetic fields (EMF) induced a significant upregulation of mRNA levels of the heat shock protein, hsp70 of p53-deficient embryonic stem cells differentiating in vitro, paralleled by a low and transient increase of c-jun, c-myc, and p21 levels in p53-deficient, but not in wild-type cells. No responses were revealed in either cell type after electromagnetic field exposure to GSM-Talk applied at similar slot-averaged specific absorption rates (SAR), but at lower time-averaged SAR values. Cardiac differentiation and cell cycle characteristics were not affected in embryonic stem and embryonic carcinoma cells after irradiation to GSM-217 EMF signals. The results indicate that the genetic background determines cellular responses to GSM modulated EMF.

Study character:

Study funded by

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