Clinical significance of different effects of static and pulsed electromagnetic fields on human osteoclast cultures

Abstract

Electromagnetic fields are known to affect the bone metabolism by modifying some relevant physiologic cell parameters of cells, even though the underlying mechanisms are still unclear. The aim of our study was to evaluate the effect of both static magnetic fields (SMFs) of the same intensity of the one generated by spinal metal devices and pulsed electromagnetic fields (PEMFs) of the same intensity used for the management of nonunion on human osteoclasts cell culture. Primary osteoclast cells were isolated from primary human osteoclast precursors and were exposed to SMFs and to PEMFs. Morphology and tartrate-resistant acid phosphatase (TRAP) activity were evaluated in the osteoclast cultures after 7, 10, and 14 days of exposure. The SMF-exposed cells show a more differentiated phenotype and a significantly higher TRAP activity after 7 and 10 days of treatment with respect to a sham control. PEMF-exposed cells have a less-differentiated phenotype after 7 days of exposure compared with the relative sham control, while the TRAP activity shows no statistically significant differences between exposed and control cells at any observation time. Our results indicate that SMFs of the same intensity of the one generated around spinal devices can affect osteoclast differentiation and activity. Aseptic loosening around titanium implants might be due in part to an increased osteoclast activity and differentiation. PEMFs of the same intensity than the one used for the management of nonunions can affect osteoclasts phenotype after 7 days of exposure, while osteoclasts TRAP activity is not affected by this kind of electromagnetic fields.

Effects of moderate intensity static magnetic fields on osteoclastic differentiation in mouse bone marrow cells

“…Direct SMF treatment decreased the number of osteoclasts and TRAP activity of BMM cells as compared to cells treated with RANKL and M-CSF. These results indicate that SMF exerts a potent inhibitory effect on osteoclast differentiation, which was consistent with a previous study of high-gradient magnetic fields in human preosteoclast FLG29.1 cells [Barnaba et al, 2012;Di et al, 2012]. In contrast, the application of 0.9 mT SMFs increased human osteoclast differentiation and TRAP activity [Barnaba et al, 2012].…”

“…As such, the effects of SMFs on osteoclastogenesis are not completely understood. SMFs increased osteoclast differentiation and tartrate‐resistant acid phosphatase (TRAP) activity, whereas pulsed electric magnetic fields (PEMFs) mildly affected osteoclast formation, but not TRAP activity, in human osteoclast precursors [Barnaba et al, ]. In contrast, a high gradient magnetic field inhibited osteoclast formation and differentiation, whereas the reduced apparent gravity enhanced osteoclastogenesis in human preosteoclast FLG29.1 cells [Di et al, ].…”

Pulsed electromagnetic fields promote bone formation by activating the sAC–cAMP–PKA–CREB signaling pathway

“…Electromagnetic fields (EMFs) of extremely low frequency have been considered to be a promising therapy for a wide range of bone diseases, such as fresh and nonunion fractures, osteoarthritis, and osteoporosis (Funk, Monsees, & Özkucur, ). Accumulating evidence has shown that EMFs promote osteogenic differentiation and mineralization of bone marrow stromal cells (BMSCs) and osteoblasts, inhibit osteoclast formation and its bone resorption activity, and prevent bone loss in animal models of disuse and ovariectomy‐induced osteoporosis (Barnaba et al, ; Chang, Chang, Tsai, & Shih, ; Chang, Chang, Wu, & Shih, ; Jing et al, , ; He, Selvamurugan, Warshaw, & Partridge, ; Hong, Kang, Yi, Kim, & Cho, ; Li et al, ; Ongaro et al, ; Schwartz et al, ; Tong et al, ; Xie et al, ; Yan et al, ; J. Zhang et al, ; Zhou et al, ). Clinical investigations further confirmed that EMFs increased bone mineral density (BMD) and prevented bone loss in the patients with osteoporosis (Garland, Adkins, Matsuno, & Stewart, ; Tabrah, Ross, Hoffmeier, & Gilbert, ).…”

In vitro effects of particulate bone substitute materials on the resorption activity of human osteoclasts

“…Understanding the phenotypic characteristics of osteoclast-like cells, as viewed by light microscopy (Kurihara et al, 1990), makes it possible to analyze both multinuclearity and cell number per field of view in the context of studying the effect of electromagnetic fields on human osteoclasts cultures (Barnaba et al, 2012). In addition, light microscopy based score systems are used in other areas, such as cartilage research or cytotoxicity assays (Changoor et al, 2011;Grogan et al, 2006).…”

“…In order to assess the quality of phenotypic cell morphology during ongoing cell culture, a score system was developed based on cell number and multinuclearity of cells per field of view (Barnaba et al, 2012;Kurihara et al, 1990) (Table 4). Scores ranged from Score 0 (PBMCs) to Score 3 (osteoclast-like morphology) ( Fig.…”