Biological effects of 6 mT static magnetic fields: a comparative study in different cell types

Aim of the present work was the comparative study of the bio-effects induced by exposure to 6 mT static magnetic field (MF) on several primary cultures and cell lines. A particular attention was dedicated to apoptosis. Cell viability, proliferation, intracellular Ca2+ concentration and morphology were also examined during the exposure of cells to static MF. Primary culture of human lymphocytes, mice thymocytes and cultures of 3DO, U937, HeLa, HepG2 and FRTL-5 cells were cultured in the presence of 6 mT static MF and different apoptosis-inducing drugs (i.e. cycloheximide, H2O2, puromycin, heat shock, etoposide). On all the different cells examined biological effects of static MF exposure were found. They were cell type-dependent but apoptotic inducer-independent. A common effect of the exposure to static MF was the promotion of apoptosis and mitosis but not of necrosis and modifications of the cell shape. Increase of the intracellular levels of Ca2+ ions were also observed. When pro-apoptotic drugs were added to static MF, the majority of cell types rescued from apoptosis. On the contrary, apoptosis of 3DO cells was significantly increased under simultaneous exposure to static MF and incubation with pro-apoptotic drugs. From these data it derives that 6 mT static MF exposure interfered with apoptosis in a cell type- and exposure time- dependent manner while the effects of static MF exposure on the apoptotic program were independent of the drugs used.