After 24 hours, cells were exposed to PEMFs for 18 hours using a PEMF generator system (Igea, Carpi, Italy). The PEMF used in this study is used clinically to treat nonunions or delayed unions and avascular necrosis of the femoral head [32] [33] [34] . The solenoids were powered using a Biostim pulse generator (Igea), a PEMF generator. The electromagnetic bioreactor applied to the cells has the following characteristics: intensity of the magnetic field, 2 ± 0.2 mT; amplitude of the induced electric tension, 5 ± 1 mV; signal frequency, 75 ± 2 Hz; and pulse duration, 1.3 ms. The stimulated multiwell was placed parallel between the two solenoids of the PEMF generator. The solenoids were placed at a distance of 10 cm and the multiwell was located on an acrylic support exactly at the center of the two solenoids. Control cultures were placed in the same incubator; nevertheless, the presence of the electromagnetic field was checked and its value was less than 0.05 mT. This value was ineffective in previous studies [38] [39] [40] [41] [42] [43] [44] [45] [46] . After 18 hours, when cultures were subconfluent, cells were processed for RNA extraction.