Static magnetic fields promote osteoblastic/cementoblastic differentiation in osteoblasts, cementoblasts, and periodontal ligament cells

Abstract

PurposeAlthough static magnetic fields (SMFs) have been used in dental prostheses and osseointegrated implants, their biological effects on osteoblastic and cementoblastic differentiation in cells involved in periodontal regeneration remain unknown. This study was undertaken to investigate the effects of SMFs (15 mT) on the osteoblastic and cementoblastic differentiation of human osteoblasts, periodontal ligament cells (PDLCs), and cementoblasts, and to explore the possible mechanisms underlying these effects.MethodsDifferentiation was evaluated by measuring alkaline phosphatase (ALP) activity, mineralized nodule formation based on Alizarin red staining, calcium content, and the expression of marker mRNAs assessed by reverse transcription polymerase chain reaction (RT-PCR). Signaling pathways were analyzed by western blotting and immunocytochemistry.ResultsThe activities of the early marker ALP and the late markers matrix mineralization and calcium content, as well as osteoblast- and cementoblast-specific gene expression in osteoblasts, PDLCs, and cementoblasts were enhanced. SMFs upregulated the expression of Wnt proteins, and increased the phosphorylation of glycogen synthase kinase-3β (GSK-3β) and total β-catenin protein expression. Furthermore, p38 and c-Jun N-terminal kinase (JNK) mitogen-activated protein kinase (MAPK), and nuclear factor-κB (NF-κB) pathways were activated.ConclusionsSMF treatment enhanced osteoblastic and/or cementoblastic differentiation in osteoblasts, cementoblasts, and PDLCs. These findings provide a molecular basis for the beneficial osteogenic and/or cementogenic effect of SMFs, which could have potential in stimulating bone or cementum formation during bone regeneration and in patients with periodontal disease.

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

“…Interestingly, weak‐to‐moderate intensity SMFs, particularly 15 mT, maximally inhibited RANKL‐induced osteoclast differentiation in vitro. This magnitude also showed the highest growth and osteoblastic differentiation of MSCs [Kim et al, ] and periodontium‐derived cells [Kim et al, ]. These results show that SMFs affected not only osteoblast function, but also osteoclast activity.…”

“…A magnet was placed horizontally below the wells, and the north (N) side of magnet was oriented towards the well. We selected the same SMF intensities that were found to stimulate osteogenic differentiation in MSCs [Kim et al, ] and periodontium‐derived cells [Kim et al, ] in our previous studies. The SMFs were established by controlling the distance between the magnet and culture plates, as previously described [Kim et al, ; Kim et al, ].…”

“…We previously demonstrated that 15 mT intensity SMF, which is a relatively weak intensity among moderate SMF intensity ranges (1 mT–1 T), can trigger earlier peri‐implant bone formation than the absence of a magnetic field in vivo [Leesungbok et al, ; Kim et al, ]. Moreover, we demonstrated that 15 mT intensity SMFs could enhance the proliferation and osteogenic differentiation of human bone marrow‐derived mesenchymal stem cells (MSCs) [Kim et al, ] and periodontium‐derived cells, such as osteoblasts, cementoblasts, and periodontal ligament cells [Kim et al, ] in vitro. As osteoblastic stromal cells in physiological conditions modulate osteoclastogenesis and osteoclastic bone resorption [Takahashi et al, ], it is assumed that SMF‐induced osteogenic differentiation in osteoblasts would also affect osteoclasts.…”

Synergistic Effects of Novel Superparamagnetic/Upconversion HA Material and Ti/Magnet Implant on Biological Performance and Long‐Term In Vivo Tracking

“…These results demonstrate that the SMF had a positive effect on cell proliferation and gene expression. Kim et al also demonstrated a positive effect of moderate SMF (15 mT) on osteoblast differentiation and osteogenic gene expression and revealed that this was related to the activation of the Wnt, p38, c‐Jun N‐terminal kinase (JNK)/mitogen‐activated protein kinase (MAPK), and NF‐ ĸ B signaling pathways . Because this study focused only on four osteogenic genes, further investigation will be necessary to determine whether the doping of Fe ions in the HA matrix will affect the expression or the signaling pathways of other genes in order to clarify the reason(s) for the slow down in cell proliferation.…”

Effects and Mechanisms of Exogenous Electromagnetic Field on Bone Cells: A Review

“…PEMF exposure increased the expressions of Wnt1, LRP5, and β‐catenin, as well as osteocalcin in both OVX and hindlimb‐suspended rat models, suggesting that PEMF may increase bone mineral density via activation of Wnt signaling pathway [Jing et al, 2013; Jing et al, 2014]. In addition, SMF has also been found to upregulate the expressions of Wnt proteins [Kim et al, 2017].…”