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Medical/biological study (experimental study)

Retinoic acid inhibits the cytoproliferative response to weak 50Hz magnetic fields in neuroblastoma cells.

Published in: Oncol Rep 2013; 29 (3): 885-894

Aim of study (acc. to author)

To test whether a magnetic field of 10 µT and 100 µT influences the proliferation of a neuroblastoma cell line, alone or in combination with retinoic acid (a retinoid applied in oncostatic therapies).
Background/further details: A previous study (Trillo et al., 2012 ) has shown a stimulating effect of a magnetic field of 100 µT in a neuroblastoma cell line.
Two experiments were conducted: In the first experiment, cells were either exposed to a 10 µT magnetic field, exposed to a 100 µT magnetic field or sham exposed. In the second experiment the cell samples were submitted to one of the following treatment methods: 1.) sham exposure, 2.) sham exposure + retinoic acid (2 µM), 3.) exposure and 4.) exposure + retinoic acid (2 µM).

Endpoint

Exposure

Exposure Parameters
Exposure 1: 50 Hz
Exposure duration: intermittent for 3 h "on" - 3 h "off" for 42 h or 90 h
General information
The cells were treated in the following groups: i) control group ii) retinoic acid treatment iii) exposure to EMF iv) retinoic acid treatment + exposure to EMF
Exposure 1
Main characteristics
Frequency 50 Hz
Type
Waveform
Exposure duration intermittent for 3 h "on" - 3 h "off" for 42 h or 90 h
Exposure setup
Exposure source
Setup two sets of Helmholtz coils with a diameter of 20 cm and 1000 turns of enamelled copper wire each, positioned 10 cm apart; five or twenty Petri dishes placed between the coils for exposure; coil sets housed in magnetically shielded Co-Netic alloy boxes which were placed inside incubators with 5 % CO2 and 37°C
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
magnetic flux density 10 µT - - - -
magnetic flux density 100 µT - - - -
Additional parameter details
environmental fields at the sample location: DC: B= 0.02 - 0.08 µT AC: B = 0.06 - 0.09 µT (rms)
Reference articles
Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated material:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

The experiments showed that exposure to magnetic fields of 10 µT or 100 µT significantly increased the proliferation and the DNA content when compared to the control samples, but did not influence the cell viability and the total protein content. No significant differences were observed between the two magnetic flux densities. However, the second experiment showed that a treatment with retinoic acid significantly reduced the proliferation in comparison to the control cell culture, independent if the cell cultures were exposed or sham exposed. Hence, no significant difference was observed between group 2 (sham exposure + retinoic acid) and group 4 (exposure + retinoic acid).
The authors conclude that a magnetic field exposure of 10 µT or 100 µT could enhance the cell proliferation in a neuroblastoma cell line and that retinoic acid may inhibit this effect. In summary, the present data could be of potential relevance to identify the mechanisms of action by which extremely low frequency magnetic fields affect human cells.
Study character:

Study funded by

  • Ministerio Espanol de Ciencia y Tecnologia (Ministry of Science and Technology), Spain
  • European Project REFLEX

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