A number of studies have reported that extremely low frequency magnetic fields (ELF-MF) can modulate proliferative processes in vitro; however, the transduction mechanisms implicated in such phenomena remain to be identified. The present study was aimed to determine whether a 50 Hz, 100 μT MF can induce cell proliferation in the human neuroblastoma line NB69, and whether the signaling pathway MAPK-ERK1/2 (Mitogen-Activated Protein Kinase - Extracellular-Signal-Regulated Kinase 1 and 2) is involved in that proliferative response. The cultures were exposed intermittently or continuously to the MF for a 63-hour duration. The continuous treatment did not induce significant changes in cell proliferation. In contrast, intermittent exposure caused statistically significant increase in the percent of cells in phase S of the cell cycle, followed by a significant increase in cell number. The intermittent treatment also induced an early, transient and repetitive activation of ERK1/2 that could be involved in the proliferative effects. In fact, both the proliferative response and the repeated activation of ERK1/2 were blocked by PD98059, the specific inhibitor of MEK (ERK kinases 1 and 2). Taken together, the described results indicate that a 50 Hz, 100 μT MF can stimulate proliferation in NB69 cells by triggering MAPK-ERK1/ 2 signaling at each of the "On" periods of an intermittent exposure.

The proliferative response of the neuroblastoma line NB69 to a 100 µT, 50 Hz magnetic field (MF) has been shown mediated by activation of the MAPK-ERK1/2 pathway. This work investigates the MF effect on the cell cycle of NB69, the participation of p38 and c-Jun N-terminal (JNK) kinases in the field-induced proliferative response and the potential involvement of reactive oxygen species (ROS) in the activation of the MAPK-ERK1/2 and -p38 signaling pathways. NB69 cultures were exposed to the 100 µT MF, either intermittently for 24, 42 or 63 h, or continuously for periods of 15 to 120 min, in the presence or absence of p38 or JNK inhibitors: SB203580 and SP600125, respectively. Antioxidant N-acetylcysteine (NAC) was used as ROS scavenger. Field exposure induced transient activation of p38, JNK and ERK1/2. The MF proliferative effect, which was mediated by changes in the cell cycle, was blocked by the p38 inhibitor, but not by the JNK inhibitor. NAC blocked the field effects on cell proliferation and p38 activation, but not those on ERK1/2 activation. The MF-induced proliferative effects are exerted through sequential upregulation of MAPK-p38 and -ERK1/2 activation, and they are likely mediated by a ROS-dependent activation of p38.

Hypertrophic scars and keloids are two different manifestations of excessive dermal fibrosis and are caused by an alteration in the normal wound-healing process. Treatment with radiofrequency (RF)-based therapies has proven to be useful in reducing hypertrophic scars. In this study, the effect of one of these radiofrequency therapies, Capacitive Resistive Electrical Transfer Therapy (CRET) on biomarkers of skin fibrosis was investigated. For this, in cultures of human myofibroblasts treated with CRET therapy or sham-treated, proliferation (XTT Assay), apoptosis (TUNEL Assay), and cell migration (Wound Closure Assay) were analyzed. Furthermore, in these cultures the expression and/or localization of extracellular matrix proteins such as α-SMA, Col I, Col III (immunofluorescence), metalloproteinases MMP1 and MMP9, MAP kinase ERK1/2, and the transcription factor NFκB were also investigated (immunoblot). The results have revealed that CRET decreases the expression of extracellular matrix proteins, modifies the expression of the metalloproteinase MMP9, and reduces the activation of NFκB with respect to controls, suggesting that this therapy could be useful for the treatment of fibrotic pathologies.

Androgenic alopecia (AGA) is the most common type of alopecia and its treatments involve drugs that have various adverse effects and are not completely effective. Radiofrequency-based therapies (RF) are an alternative for AGA treatment. Although there is increasing clinical evidence of the effectiveness of RF for alopecia, its effects at the tissue and cellular level have not been studied in detail. The objective of this study was to analyze ex vivo the potential effect of RF currents used in capacitive resistive electrical transfer (CRET) therapy on AGA. Hair follicles (HFs) were donated by patients with AGA and treated with CRET. AGA-HFs were exposed in vitro to intermittent 448 kHz electric current in subthermal conditions. Cell proliferation (Ki67), apoptosis (TUNEL assay), differentiation (β-catenin), integrity (collagen and MMP9), thickness of the epidermis surrounding HF, proportion of bulge cells and melanoblasts in AGA-HF were analyzed by immunohistochemistry. CRET increased proliferation and decreased death of different populations of AGA-HF cells. In addition, the melanoblasts increased in bulge and the epidermis surrounding the hair follicle thickened. These results support the effectiveness of RF-based therapies for the treatment of alopecia. However, clinical trials are necessary to know the true effectiveness of CRET therapy and other RF therapies for AGA treatment.

Previous studies have shown that a 63-hour, intermittent exposure to a 50 Hz, 100 μT magnetic field (MF) induces in the NB69 line of human neuroblastoma a proliferative response that is mediated by activation of the MAPK pathways ERK1/2 and p38. The present study aims to investigate the potential involvement of the epidermal growth factor receptor (EGFR) in the field-induced cell proliferation and activation of MAPK pathways. NB69 cultures were MF- or sham-exposed for 5 to 30 minute intervals and 63 hours. Cell proliferation and activation of MAPK-ERK1/2, -p38 and -JNK was analyzed in the presence or absence of erlotinib, an effective inhibitor of EGFR tyrosine kinase. The expression of p-EGFR and MMP-9 in the presence or absence of MF was also studied. Between 3 and 7 replicates of each experiment were performed, using between 3 and 4 samples per experimental condition and replicate. At the end of each replicate, the samples were analyzed at short times (5-30 min) through immunofluorescence and Western blotting, and the growth response was assessed (63 hours interval) through dye exclusion with Trypan blue. The results confirmed that field exposure induces cell proliferation and activation of ERK1/2, p38 and JNK, and revealed that these effects were blocked with erlotinib. The data also showed that, compared to shamexposed controls, the MF exposure induces early and transient increases in the expression of p-EGFR and MMP-9 at 15 and 5 min from the exposure onset, respectively. The obtained results reveal that the activation of the MAPK-ERK1/2 and -p38 pathways by the MF is mediated by the EGF receptor. Taken together with our previously published results, this dataset suggests that the proliferative response induced in NB69 by a 63-hour exposure to a weak, power frequency MF, is mediated by early transient activation of EGFR in which MMP-9 would be involved.