Study type: Medical/biological study (experimental study)

Non-thermal effects of terahertz radiation on gene expression in mouse stem cells. med./bio.

Published in: Biomed Opt Express 2011; 2 (9): 2679-2689

Aim of study (acc. to author)

Mesenchymal mouse stem cells were exposed to Terahertz waves to study whether mammalian cells exhibit specific cellular and/or molecular effects, unrelated to the temperature changes. To examine the eventual thermal effect locally, i.e. in the cells, the Terahertz-induced transcriptional activation of hyperthermic genes was quantified, and their expression levels were compared with previously reported differentially expressed genes (Bock et al. 2010).

Background/further details

The irradiations were performed at biologically-low temperatures (26-27°C), and at low Terahertz power densities (1-3 mW/cm²), in order to minimize thermal effects on the gene activity. To analyze the possible changes in the temperature, simulations and experimental measurements were applied.

Endpoint

Exposure

Exposure Parameters
Exposure 1: 10 THz
Modulation type: pulsed
Exposure duration: continuous for 2 h or 9 h
Exposure 2: 2.52 THz
Modulation type: CW
Exposure duration: continuous for 2 h

Exposure 1

Main characteristics
Frequency 10 THz
Type
Exposure duration continuous for 2 h or 9 h
Additional info broad band (1-30 THz) radiation centered at 10 THz
Modulation
Modulation type pulsed
Pulse width 0.035 ps
Repetition frequency 1 kHz
Exposure setup
Exposure source
Setup laser beam directed by a 90° off-axis parabolic gold mirror onto the bottom of the 4 cm diameter parafilm-sealed tissue culture dish
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 1.2 mW/cm² - measured - at the center of the beam through empty plate
power density 0.25 mW/cm² - measured - near the edge of the empty culture plate
power density 1 mW/cm² mean estimated - -

Exposure 2

Main characteristics
Frequency 2.52 THz
Type
Exposure duration continuous for 2 h
Modulation
Modulation type CW
Exposure setup
Exposure source
Setup laser beam directed by a 90° off-axis parabolic gold mirror onto the bottom of the 4 cm diameter parafilm-sealed tissue culture dish
Sham exposure A sham exposure was conducted.
Parameters
Measurand Value Type Method Mass Remarks
power density 3 mW/cm² - measured - at the center of the beam

Exposed system:

Methods Endpoint/measurement parameters/methodology

Investigated system:
Time of investigation:
  • after exposure

Main outcome of study (acc. to author)

No cell death was visually observed. No effects on the cell membranes were visually discernable. No lipid inclusions were found in the control samples or in the samples that were exposed to 2 hours of CW irradiation (exposure 2). However, lipid droplet-like inclusions were observed in the cellular cytoplasm after 2 and 9 hours of broad-band exposure (exposure 1) and the morphological changes seemed to be dependent of the exposure duration (fewer inclusions after 2 h than after 9 h) and frequency.
Temperature increases were minimal, and the expression of the investigated heat shock proteins (hsp105, hsp90 and CPR) was unaffected, while the gene expression of the other genes (adiponectin, GLUT4, and PPARG) showed clear effects of the Terahertz irradiation after prolonged, broad-band exposure (as revealed in Bock et al. 2010). These effects where observed under irradiation conditions that caused minimal temperature changes, and in the explicit absence of any discernable response of heat shock and cellular stress genes.

Study character:

Study funded by

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