Effects of THz exposure on human primary keratinocyte differentiation and viability

Primary human keratinocytes can be driven, in vitro, to differentiate, via activation of transglutaminases, by raising the culture medium calcium concentration above 1 mM. This results in transglutaminase regulated cross linking of specific amino acids with resultant cornified envelope formation. The differentiation was monitored via the incorporation of fluorescein cadaverine into the cornified envelops. This differentiation assay was combined with assessment of reductive capacity of resazurin, as a measure of cell activity/viability. One primary aim is to assess the effects of THz radiation on human skin, since medical imaging of the body through the skin is envisaged. Human keratinocytes, at passage 2 from isolation, were grown to confluence, and transported in a buffered salt solution at 22 degreesC. The exposure to the THz source was for 10, 20 or 30 minutes at room temperature. No donor specific inhibition or stimulation of cell activity, compared with non-exposed cells, was noted following exposure in the range 1 to 3 THz, at up to 0.45J/cm(2). The differentiation also occurred in a normal way, for exposed and non-exposed cells, with the FC incorporation increasing between day 3 and day 8, as previously noted.