Medical/biological study (experimental study)

Distinct Epidermal Keratinocytes Respond to Extremely Low-Frequency Electromagnetic Fields Differently med./bio.

By: Huang CY, Chuang CY, Shu WY, Chang CW, Chen CR, Fan TC, Hsu IC

Published in: PLoS One 2014; 9 (11): e113424-1-e113424-7

Aim of study (acc. to author)

To investigate whether extremely low frequency magnetic fields influence the cell cycle in normal epidermal keratinocytes.

Background/further details

In a previous study, the authors found that extremely low frequency magnetic fields caused a cell cycle arrest potentially through the activation of the ATM-Chk2-p21 pathway in human keratinocyte HaCaT cells (Huang et al.).
Ionizing radiation (UV-B, 21.5 J/m²) was performed as a positive control. Cell proliferation and cell viability experiments were additionally performed with HaCaT cells.

Endpoint

molecular biosynthesis: gene expression of cell cycle-related genes, protein expression
cell viability/cell division/proliferation: cell proliferation, cell viability, cell cycle distribution

Exposure

- 50/60 Hz
- magnetic field

Exposure	Parameters
Exposure 1: 60 Hz Exposure duration: continuous up to 144 hours (24, 48, 72, 96, 120, 144 hours)	magnetic flux density: 1.5 mT

Exposure 1

Main characteristics

Frequency	60 Hz
Type	magnetic field
Exposure duration	continuous up to 144 hours (24, 48, 72, 96, 120, 144 hours)

Exposure setup

Exposure source	Helmholtz coils
Setup	coil system generated a uniform 1.5 mT magnetic field; temperature inside the incubator was 36.9 ± 0.3°C
Sham exposure	A sham exposure was conducted.
Additional info	all sham exposed cells were cultured in a chamber magnetically shielded using a mumetal box in the same incubator in which the exposed cells were incubated

Parameters

Measurand	Value	Type	Method	Mass	Remarks
magnetic flux density	1.5 mT	-	-	-	-

Additional parameter details

in unexposed environemt: 1.5 µT± 0.03 µT

Reference articles

Huang CY et al. (2014): Extremely Low-Frequency Electromagnetic Fields Cause G1 Phase Arrest through the Activation of the ATM-Chk2-p21 Pathway

Exposed system:

intact cell/cell culture
human epidermal keratinocytes (derived from neonatal foreskin) and HaCaT cells (human keratinocytes)

Methods Endpoint/measurement parameters/methodology

molecular biosynthesis: gene expression of the cell cycle-related genes CDKN1A (encodes cyclin-dependent kinase inhibitor 1, also called p21), CDC25B, CDC20, CDC2, CCNA2, CCNB1, GADD45A, CCND2, CCNE1, CDK2, CDK4 and CDK6 (quantitative real-time PCR); protein expression of ATM, phosphorylated ATM Ser1981, Chk2, phosphorylated Chk2, Thr68, p53, phosphorylated p53, Ser15 (Western blot)
cell viability/cell division/proliferation: cell proliferation (trypan blue staining, hemocytometer, microscopy); cell viability (Giemsa staining, colony forming units); cell cycle distribution (propidium iodide staining, flow cytometry)

Investigated system:

isolated bio./chem. substance
DNA/RNA
intact cell/cell culture

Time of investigation:

after exposure

Main outcome of study (acc. to author)

Extremely low frequency magnetic fields do not influence cell proliferation, cell viability, cell cycle distribution as well as gene expression and protein expression in keratinocytes derived from neonatal foreskin when compared to sham exposure. However, cell proliferation and cell viability were significantly decreased in exposed HaCaT cells in comparison to sham exposed ones. Moreover, an additional experiment with simultaneous exposure of the two cell lines showed that the keratinocytes derived from neonatal foreskin and the HaCaT cells exhibited distinct responses to the magnetic field.
The authors conclude that the biological effects of extremely low frequency magnetic fields are cell type specific. These findings could present an explanation for the inconsistent results in previous studies using various experimental models.

Study character:

medical/biological study
experimental study
full/main study

Study funded by

National Science Council, Taiwan

Naghibzadeh M et al. (2020): The effect of electromagnetic field on decreasing and increasing of the growth and proliferation rate of dermal fibroblast cell
Koziorowska A et al. (2017): Electromagnetic field of extremely low frequency (60Hz and 120Hz) effects the cell cycle progression and the metabolic activity of the anterior pituitary gland cells in vitro
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