Hsp70 expression in a human trophoblast cell line and its modulation by environmental stress factors.

Aim: Heat shock proteins (Hsps) are a class of cytoprotective proteins acting as molecular chaperones, and their over-expression is an ubiquitous mechanism to cope with stress. We performed the first in vitro characterization of the Hsp70 expression in the human trophoblast-derived HTR-8/SVneo cells. We studied basal levels of HSP70 and HSC70 in control cells and in cells exposed to heat and to high frequency electromagnetic fields (HF-EMF), which represent an emerging area of interest for human health. Methods: Cells were exposed to heat using a thermostat or irradiated in an exposure system developed and built by IT’IS Foundation (Zurich, Switzerland). HSP70 and HSC70 levels were evaluated by Western blotting and cell viability was assessed by MTT assay. Results: Expression of both HSP70 and HSC70 was detected in control cells. Induction of Hsp70 was a function of increasing temperature of exposure, reaching the maximum after 1 h at 43°C and 3 h of post-stress recovery. It became significantly higher than in control cells after 45 min of thermal stress at 43°C. HSC70 expression remained unchanged at any condition tested. Under our experimental conditions (1 h, GSM-217 Hz, SAR = 2 W/kg) HF-EMF exposure alone or in combination with heat (1h, 43°C) did not affect the Hsp70 expression. Conclusion: HTR-8/SVneo cells represent a good model for the in vitro study of molecular mechanisms of placentation; our data on Hsp70 expression provide the basis for assessing the effect of other stress stimuli on placental tissues and elucidating the possible role of these proteins as stress markers and warning of abnormal early pregnancies.