To examine whether radiofrequency electromagnetic fields and estradiol regulate cell-cell and cell-extracellular matrix interactions in a trophoblast cell line as a model for the early development of the placenta during gestation.
A critical step in the development of the human placenta is the differentiation of trophoblast stem cells. In this process the trophoblast cells and the extracellular matrix are included, which interact with diverse adhesion molecules such as connexins and integrins. Integrins are transmembrane proteins that mediate the attachment between cells as well as between cells and the extracellular matrix. Therefore, the effects of radiofrequency fields and estradiol on connexins, integrins and estrogen receptor gene expression and protein expression were studied, as well as on ultrastructural cell features in gestational tissue (trophoblast cell line).
Cell cultures were subjected to different treatment conditions: 1.) sham exposure, 2.) radiofrequency exposure, 3.) addition of 17-estradiol into the culture medium (10-6 M) and 4.) combination of radiofrequency exposure + addition of 17-estradiol (10-6 M).
Cells were exposed in 4 groups: 1.) sham exposure, 2.) radiofrequency exposure, 3.) addition of 17-estradiol into the culture medium, 4.) co-exposure of radiofrequency exposure + addition of 17-estradiol.
| Frequency | 1,800 MHz |
|---|---|
| Type | |
| Exposure duration | continuous for 1 h |
| Modulation type | pulsed |
|---|---|
| Repetition frequency | 217 Hz |
| Pulse type | rectangular |
| Exposure source | |
|---|---|
| Setup | two 128.5 mm x 65 mm x 424 mm brass single mode waveguide resonators; 6 petri dishes kept on plastic holders inside the resonators at the H-field maximum of the standing wave |
| Sham exposure | A sham exposure was conducted. |
| Measurand | Value | Type | Method | Mass | Remarks |
|---|---|---|---|---|---|
| SAR | 2 W/kg | average over time | measured | - | - |
Radiofrequency exposure, an addition of estradiol and their combination significantly increased gene expression of connexin 40 and connexin 43 in comparison to the control group. Radiofrequency exposure alone significantly decreased the gene expression of integrins (alpha1, alpha5, beta1) and estrogen receptor beta compared to the control group, while an addition of estradiol or a combination of estradiol with radiofrequency exposure led to a significant increase. No changes occurred regarding protein expression.
In the sham exposed and the radiofrequency exposed cell cultures, the estrogen receptor beta was mainly localized in the cytoplasm, while in the cell cultures treated with estradiol and with a combination of estradiol and radiofrequency exposure, it was mainly concentrated in the nuclear region.
Electron microscopy showed a decrease in cellular adhesion in the radiofrequency exposed cell culture compared to the sham exposed cultures, while an addition of estradiol prevented this effect.
The data indicate that exposure of trophoblasts to radiofrequency electromagnetic fields could modify gene expression and cellular ultrastructure. However, an addition of 17-estradiol could prevent these effects.
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