Medical/biological study (experimental study)

Determination of death thresholds and identification of Terahertz (THz)-specific gene expression signatures med./bio.

By: Wilmink GJ, Ibey BL, Roth CL, Vincelette RL, Rivest BD, Horn CB, Bernhard J, Roberson D, Roach WP

Published in: Optical interactions with tissues and cells XXI: 25 - 27 January 2010, San Francisco, California, United States. SPIE, 2010: 7562 OK-1-7562 OK-8

doi:10.1117/12.844917

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Aim of study (acc. to author)

To study if high-power THz radiation causes cellular and/or molecular effects in human Jurkat cells and dermal fibroblast cell lines.

Endpoint

Exposure

- 2.52 THz
- TeraHz

Exposure	Parameters
Exposure 1: 2.52 THz Exposure duration: continuous for up to 15 s cell viability experiments with fibroblasts	power density: 227 mW/cm²
Exposure 2: 2.52 THz Exposure duration: continuous for 1 min or 2 min gene expression experiments	power density: 227 mW/cm²
Exposure 3: 2.52 THz Exposure duration: continuous for 5, 10, 20, 30, 40 min cell viability experiments with Jurkat cells	power density: 227 mW/cm²

Exposure 1

Main characteristics

Frequency	2.52 THz
Type	electromagnetic field
Exposure duration	continuous for up to 15 s
Additional info	cell viability experiments with fibroblasts

Exposure setup

Exposure source	far-infrared optically pumped THz laser system
Chamber	25.4 mm 90° off-axis gold parabolic mirror used to focus the THz beam on the cell cultures in 35 mm petri dishes
Setup	exposure system consists of a 50 W tunable CO₂ pump laser, a pump frequency laser lock, and two non-folded THz laser cells; CO₂ laser (tuned to 9P36) used to excite the rotational bands of methanol (at 380 mTorr), difluoromethane and methyl chloride
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
power density	227 mW/cm²	-	-	-	-

Exposure 2

Main characteristics

Frequency	2.52 THz
Type	electromagnetic field
Exposure duration	continuous for 1 min or 2 min
Additional info	gene expression experiments

Exposure setup

Exposure source	same setup as exposure 1
Setup	cells exposed in plates with 24 wells
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
power density	227 mW/cm²	-	-	-	-

Exposure 3

Main characteristics

Frequency	2.52 THz
Type	electromagnetic field
Exposure duration	continuous for 5, 10, 20, 30, 40 min
Additional info	cell viability experiments with Jurkat cells

Exposure setup

Exposure source	same setup as exposure 1
Setup	cells seeded in plates with 96 wells
Sham exposure	A sham exposure was conducted.

Parameters

Measurand	Value	Type	Method	Mass	Remarks
power density	227 mW/cm²	-	-	-	-

Exposed system:

intact cell/cell culture
Jurkat cells (human lymphoblastoid T cells) and human dermal fibroblasts

Methods Endpoint/measurement parameters/methodology

molecular biosynthesis: gene expression (in fibroblasts; mRNA microarray)
cell viability/cell division/proliferation: cell viability in (adherent) fibroblasts (propidium iodide and FITC-annexin V staining; confocal microscopy); cell viability in Jurkat cells (MTT assay); necrotic and apoptotic cell death in Jurkat cells (propidium iodide and FITC-annexin V staining; flow cytometry)

Investigated system:

DNA/RNA
intact cell/cell culture

Time of investigation:

after exposure

Main outcome of study (acc. to author)

The MTT assay showed that 60% of the Jurkat cells survived the 30-minutes THz exposure, whereas only 20% survived the 40-minutes exposure. The flow cytometry data showed similar results and provided additional evidence suggesting that THz-induced cell death was mediated by both necrotic and apoptotic processes.
The preliminary confocal microscopy data suggested that cells exposed to THz radiation for 12 seconds or longer show appreciable signs of cell death.
The preliminary microarray data showed that dermal fibroblasts upregulated several genes when exposed to THz irradiation (primarily inflammatory cytokines).
Overall, these findings provide evidence for the cellular and molecular effects of THz irradiation.

Study character:

Study funded by

Air Force Research Laboratory's (AFRL) Human Effectiveness Directorate, USA
HQ AF/SGRS (Headquarters United States Air Force/Surgeon General Research and Development Divison), USA

Wilmink GJ et al. (2011): In vitro investigation of the biological effects associated with human dermal fibroblasts exposed to 2.52 THz radiation
Hintzsche H et al. (2011): Terahertz radiation induces spindle disturbances in human-hamster hybrid cells
Alexandrov BS et al. (2011): Non-thermal effects of terahertz radiation on gene expression in mouse stem cells
Alexandrov BS et al. (2010): DNA Breathing Dynamics in the Presence of a Terahertz Field
Bock J et al. (2010): Mammalian Stem Cells Reprogramming in Response to Terahertz Radiation
Korenstein-Ilan A et al. (2008): Terahertz radiation increases genomic instability in human lymphocytes
Bourne N et al. (2008): The effects of terahertz radiation on human keratinocyte primary cultures and neural cell cultures
Zeni O et al. (2007): Cytogenetic Observations In Human Peripheral Blood Leukocytes Following In Vitro Exposure To THz Radiation: A Pilot Study
Scarfi MR et al. (2003): THz Exposure of Whole Blood for the Study of Biological Effects on Human Lymphocytes
Clothier RH et al. (2003): Effects of THz exposure on human primary keratinocyte differentiation and viability
Smye SW et al. (2001): The interaction between Terahertz radiation and biological tissue

Determination of death thresholds and identification of Terahertz (THz)-specific gene expression signatures med./bio.

Aim of study (acc. to author)

Endpoint

Exposure

Exposure 1

Main characteristics

Exposure setup

Parameters

Exposure 2

Main characteristics

Exposure setup

Parameters

Exposure 3

Main characteristics

Exposure setup

Parameters

Methods Endpoint/measurement parameters/methodology

Main outcome of study (acc. to author)

Study funded by

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