Synergistic effect of electromagnetic fields and nanomagnetic particles on osteogenesis through calcium channels and p‐ERK signaling

Abstract

Electromagnetic fields (EMFs) are widely used in a number of cell therapies and bone disorder treatments, and nanomagnetic particles (NMPs) also promote cell activity. In this study, we investigated the synergistic effects of EMFs and NMPs on the osteogenesis of the human Saos‐2 osteoblast cell line and in a rat calvarial defect model. The Saos‐2 cells and critical‐size calvarial defects of the rats were exposed to EMF (1 mT, 45 Hz, 8 h/day) with or without Fe3O4 NMPs. Biocompatibility was evaluated with MTT (3‐(4,5‐dimethylthiazol‐2‐yl)‐2,5‐diphenyltetrazolium bromide) and LDH (lactate dehydrogenase) assays. This analysis showed that NMP and EMF did not induce cell toxicity. Quantitative reverse‐transcription polymerase chain reaction indicated that the osteogenesis‐related markers were highly expressed in the NMP‐incorporated Saos‐2 cells after exposure to EMF. Also, the expression of gene‐encoding proteins involved in calcium channels was activated and the calcium concentration of the NMP‐incorporated + EMF‐exposed group was increased compared with the control group. In particular, in the NMP‐incorporated + EMF‐exposed group, all osteogenic proteins were more abundantly expressed than in the control group. This indicated that the NMP incorporation + EMF exposure induced a signaling pathway through activation of p‐ERK and calcium channels. Also, in vivo evaluation revealed that rat calvarial defects treated with EMFs and NMPs had good regeneration results with new bone formation and increased mineral density after 6 weeks. Altogether, these results suggest that NMP treatment or EMF exposure of Saos‐2 cells can increase osteogenic activity and NMP incorporation following EMF exposure which is synergistically efficient for osteogenesis.

The bioelectrical properties of bone tissue

“…Zhang et al 42 Wright et al 43 McDonald 46 Miyauchi et al 50 Intracellular signaling pathways Influx of ions within cytosol in response to electrical stimuli can activate calciumcalmodulin-calcinueurin-NFAT, RAS and ERK signaling pathways, which in turn promote transcription of various osteogenic genes Winslow et al 52 Zou et al 53 Wu et al 54 Kim et al 55 Cell surface receptors Some cell surface receptors, such as that for epidermal growth factor (EGF), fibronectin and concanavalin, have been reported to undergo redistribution on the cell membrane, in response to electrical stimuli, which in turn modulates cell adhesion, spreading and migration…”

“…Indeed, upregulation of TGF‐β expression induced by electrical stimuli via the calcium/calmodulin signaling pathway, appears to play a key role in bone defect healing and regeneration 48 . Besides the calcineurin‐calmodulin‐NFAT signaling cascade, elevated intracellular Ca 2+ levels can also activate the Ras and extracellular signal‐related protein kinase (ERK) signaling pathways that promote transcription of pro‐osteogenic genes such as Runx2 55–57 . Additionally, elevated intracellular Ca 2+ levels can promote cell adhesion by facilitating the binding of integrin to fibronectin, 58 as well as promoting cell migration by activating gelsolin to release more actin 59 …”

Reduction of Osteoclastic Differentiation of Raw 264.7 Cells by EMF Exposure through TRPV4 and p-CREB Pathway

“…In addition, our previous study revealed that osteogenesis-related markers were highly expressed in the EMF-exposed Saos-2 cells. Furthermore, in vivo experiments using the rat calvarial bone defect model showed that the EMF-exposed group increased bone mass/volume, mineral density, and bone regeneration in defects compared to the control group [ 35 ].…”

Effect of Cold Atmospheric Plasma (CAP) on Osteogenic Differentiation Potential of Human Osteoblasts

“…A distance-related increase in LDH secretion of cell monolayers has not been described for DBD plasma devices, which could be due to the fact that CAP has various components that have a different effect on cells, such as the production of reactive species or the emission of electromagnetic fields or ultraviolet radiation [ 35 ], which could have different effects at a greater distance. For example, other authors have described the effects of electromagnetic fields or UV light on LDH release [ 36 , 37 ]. It may be that at greater distances, only single components of the plasma affect the cells negatively.…”