Low frequency pulsed electromagnetic field affects proliferation, tissue-specific gene expression, and cytokines release of human tendon cells

Low frequency pulsed electromagnetic field (PEMF) has proven to be effective in the modulation of bone and cartilage tissue functional responsiveness, but its effect on tendon tissue and tendon cells (TCs) is still underinvestigated. PEMF treatment (1.5 mT, 75 Hz) was assessed on primary TCs, harvested from semitendinosus and gracilis tendons of eight patients, under different experimental conditions (4, 8, 12 h). Quantitative PCR analyses were conducted to identify the possible effect of PEMF on tendon-specific gene transcription (scleraxis, SCX and type I collagen, COL1A1); the release of pro- and anti-inflammatory cytokines and of vascular endothelial growth factor (VEGF) was also assessed. Our findings show that PEMF exposure is not cytotoxic and is able to stimulate TCs' proliferation. The increase of SCX and COL1A1 in PEMF-treated cells was positively correlated to the treatment length. The release of anti-inflammatory cytokines in TCs treated with PEMF for 8 and 12 h was significantly higher in comparison with untreated cells, while the production of pro-inflammatory cytokines was not affected. A dramatically higher increase of VEGF-A mRNA transcription and of its related protein was observed after PEMF exposure. Our data demonstrated that PEMF positively influence, in a dose-dependent manner, the proliferation, tendon-specific marker expression, and release of anti-inflammatory cytokines and angiogenic factor in a healthy human TCs culture model.