Pulsed electromagnetic fields inhibit human osteoclast formation and gene expression via osteoblasts

Clavicle fracture and triathlon performance: a case report

BACKGROUND

Collarbone fracture is a common injury, particularly among athletes involved in contact sports and participating in endurance activities. Conventional treatment requires surgery and postoperative immobilization, resulting in an average return-to-sport timeframe of approximately 13 weeks. This case challenges the established treatment protocols, aiming to expedite recovery and enable a quicker resumption of high-intensity athletic activities.

CASE PRESENTATION

A 24-year-old Caucasian athlete completed a Half-Ironman Triathlon (70.3) merely three weeks post-collarbone fracture. Utilizing Extracorporeal Magneto-Transduction Therapy (EMTT) alongside surgical intervention, the patient achieved accelerated healing and remarkable performance outcomes without encountering any adverse effects.

CONCLUSIONS

The integration of EMTT into the treatment paradigm for bone fractures alters the traditional understanding of recovery timelines and rehabilitation strategies. This case highlights the potential benefits of electromagnetic wave therapy in expediting the healing process and enabling athletes to resume high-level sports activities at an earlier stage.

Signalling pathways underlying pulsed electromagnetic fields in bone repair

Pulsed electromagnetic field (PEMF) stimulation is a prospective non-invasive and safe physical therapy strategy for accelerating bone repair. PEMFs can activate signalling pathways, modulate ion channels, and regulate the expression of bone-related genes to enhance osteoblast activity and promote the regeneration of neural and vascular tissues, thereby accelerating bone formation during bone repair. Although their mechanisms of action remain unclear, recent studies provide ample evidence of the effects of PEMF on bone repair. In this review, we present the progress of research exploring the effects of PEMF on bone repair and systematically elucidate the mechanisms involved in PEMF-induced bone repair. Additionally, the potential clinical significance of PEMF therapy in fracture healing is underscored. Thus, this review seeks to provide a sufficient theoretical basis for the application of PEMFs in bone repair.

Effect of the pulsed electromagnetic field in the repair of a calvaria critical bone defect in rats: cone beam computed tomographic and histomorphometric analysis.: PEMF in the repair of a calvaria critical bone defect: CBCT analyses

INTRODUCTION

The present study evaluated the effect of two protocols of Pulsed Electromagnetic Field (PEMF) therapy on bone neoformation on calvaria critical defects in rats.

MATERIAL & METHODS

96 rats were randomly divided into 3 groups: Control Group (CG; n=32); Test Group - PEMF 1 hour (TG1h; n=32) and Test Group - PEMF 3 hour (TG3h; n=32). A Critical-size Bone Defect (CSD) was surgically created in the calvaria of rats. The animals in the test groups were exposure to PEMF for 5 days a week. The animals were euthanized at 14, 21, 45 and 60 days. The specimens were processed for volume and texture (TAn) analysis, by Cone Beam Computed Tomography (CBCT) and histomorphometric analysis, RESULTS: Histomorphometric and volume analyses revealed that there was no statistically significant difference in the repair of bone defects between groups receiving PEMF therapy and CG. TAn revealed a statistically significant difference between the groups only for the entropy parameter, in which TG1h group presented a higher value compared to CG on 21 days. TG1h and TG3h did not accelerate bone repair in calvarial critical size defect and the parameters of PEMF should be considered.

DISCUSSION

This study showed that PEMF application on CSD in rats does not accelerate bone repair. Although literature showed a positive association in biostimulation on bone tissue with the parameters applied, studies with other PEMF parameters are essential to verify improving this study design.

The Possible Role of Electrical Stimulation in Osteoporosis: A Narrative Review

Osteoporosis is mainly a geriatric disease with a high incidence, and the resulting spinal fractures and hip fractures cause great harm to patients. Anti-osteoporosis drugs are the main treatment for osteoporosis currently, but these drugs have potential clinical limitations and side effects, so the development of new therapies is of great significance to patients with osteoporosis. Electrical stimulation therapy mainly includes pulsed electromagnetic fields (PEMF), direct current (DC), and capacitive coupling (CC). Meanwhile, electrical stimulation therapy is clinically convenient without side effects. In recent years, many researchers have explored the use of electrical stimulation therapy for osteoporosis. Based on this, the role of electrical stimulation therapy in osteoporosis was summarized. In the future, electrical stimulation might become a new treatment for osteoporosis.

Effects of pulsed electromagnetic fields on tumor cell viability: a meta-analysis of in vitro randomized controlled experiments

Malignant tumor treatment remains a big challenge till now, and expanding literature indicated that pulsed electromagnetic fields (PEMF) is promising in tumor treatment with the advantage of safety and being economical, but it is still controversial on whether PEMF could affect the tumor cell viability. Therefore, we conducted the meta-analysis to evaluate effects of PEMF on tumor cell viability. The PubMed, EMBASE, Web of Science, and Cochrane Library databases were searched for studies published up to February 2021. Studies on the direct effects of PEMF on tumor cell viability, determined using colorimetric analysis, were included. Two authors extracted the data and completed the quality assessment. A meta-analysis was performed to calculate the absorbance values and 95% confidence intervals (CIs) using random-effects models. Seven studies, including 32 randomized controlled experiments, were analyzed. Compared with the control group, tumor cell viability in the PEMF exposure group was obviously lower (SMD, -0.67; 95% CI: -1.12 to -0.22). The subgroup meta-analysis results showed that PEMF significantly reduced epithelial cancer cell viability (SMD, -0.58; 95% CI: -0.92 to -0.23) but had no influence on stromal tumor cell viability (SMD, -0.93; 95% CI: -0.21 to 0.15). Our study demonstrated that PEMF could inhibit tumor cell proliferation to some extent, but the risk of bias and high heterogeneity (I² > 75%) weakened the strength of the conclusions drawn from the analysis.

Synergic effects of extremely low-frequency electromagnetic field and betaine on in vitro osteogenic differentiation of human adipose tissue-derived mesenchymal stem cells

Human adipose tissue-derived mesenchymal stem cells (hADSCs) due to easy extraction, relative abundance, in vitro expansion and differentiation potential, frozen storage capability, and ability to secrete cytokines, compared to other stem cells, are appropriate candidate in regenerative medicine. Extremely low-frequency electromagnetic fields (ELF-EMF) and betaine are two safe factors in bone lesions repair. This study was designed to assess the osteogenic differentiation potential of these factors on hADSCs. The samples were collected from women undergoing liposuction after obtaining written consent. The hADSCs were extracted and treated with osteogenesis differentiation medium (OD) as the positive control, with OD and betaine (BET group), with OD and EMF (EMF group), and with OD and betaine and EMF (BET+EMF group) for 21 d; the negative control consisted of cells without treatment. Betaine 10 mM and EMF with 50-Hz frequency, 1-mT intensity (8 h daily), and in the form of sinus wave were used. Osteogenic differentiation was evaluated by Alizarin Red staining, alkaline phosphatase activity, calcium deposition, and real-time PCR. A significant increase in calcium deposition in the BET+EMF group was observed compared to the other groups. The activity of alkaline phosphatase in the positive control and BET groups was increased significantly compared to EMF and BET + EMF groups and a significant increase of this enzyme activity in the BET + EMF compared to EMF group was observed. The expression of RUNX2 and OCN genes in the EMF-treated groups were significantly reduced compared to the non-EMF-treated groups, and BET+EMF showed a significant increase of RUNX2 gene expression as compared the EMF group. The ELF-EMF leads to a decrease in the osteogenic differentiation and the expression RUNX2 and OCN genes in hADSCs. But osteogenic differentiation and RUNX2 gene expression were increased post-induction by betaine. The synergic effect of betaine and EMF on the osteogenic differentiation and related genes expression of hADSCs was higher than EMF.

Pulsed electromagnetic field (PEMF) transiently stimulates the rate of mineralization in a 3-dimensional ring culture model of osteogenesis

Pulsed Electromagnetic Field (PEMF) has shown efficacy in bone repair and yet the optimum characteristics of this modality and its molecular mechanism remain unclear. To determine the effects of timing of PEMF treatment, we present a novel three-dimensional culture model of osteogenesis that demonstrates strong de novo generation of collagen and mineral matrix and exhibits stimulation by PEMF in multiple stages over 62 days of culture. Mouse postnatal day 2 calvarial pre-osteoblasts were cast within and around Teflon rings by polymerization of fibrinogen and cultured suspended without contact with tissue culture plastic. Ring constructs were exposed to PEMF for 4h/day for the entire culture (Daily), or just during Day1-Day10, Day11-Day 27, or Day28-Day63 and cultured without PEMF for the preceding or remaining days, and compared to no-PEMF controls. PEMF was conducted as HF Physio, 40.85 kHz frequency with a 67 ms burst period and an amplitude of 1.19 mT. Osteogenesis was kinetically monitored by repeated fluorescence measurements of continuously present Alizarin Red S (ARS) and periodically confirmed by micro-CT. PEMF treatment induced early-onset and statistically significant transient stimulation (~4-fold) of the mineralization rate when PEMF was applied Daily, or during D1-D10 and D11-D27. Stimulation was apparent but not significant between D28-D63 by ARS but was significant at D63 by micro-CT. PEMF also shifted the micro-CT density profiles to higher densities in each PEMF treatment group. Ring culture generated tissue with a mineral:matrix ratio of 2.0 by thermogravimetric analysis (80% of the calvaria control), and the deposited crystal structure was 50% hydroxyapatite by X-ray diffraction (63% of the calvaria and femur controls), independent of PEMF. These results were consistent with backscatter, secondary electron, and elemental analysis by scanning electron microscopy. Thus, in a defined, strong osteogenic environment, PEMF applied at different times was capable of further stimulation of osteogenesis with the potential to enhance bone repair.

Do polyunsaturated fatty acids protect against bone loss in our aging and osteoporotic population?

Age-related bone loss is inevitable in both men and women and there will soon be more people of extreme old age than ever before. Osteoporosis is a common chronic disease and as the proportion of older people, rate of obesity and the length of life increases, a rise in age-related degenerating bone diseases, disability, and prolonged dependency is projected. Fragility fractures are one of the most severe complications associated with both primary and secondary osteoporosis and current treatment strategies target weight-bearing exercise and pharmacological intervention, both with limited long-term success. Obesity and osteoporosis are intimately interrelated, and diet is a variable that plays a significant role in bone regeneration and repair. The Western Diet is characterized by its unhealthy components, specifically excess amounts of saturated fat intake. This review examines the impact of saturated and polyunsaturated fatty acid consumption on chronic inflammation, osteogenesis, bone architecture, and strength and explores the hypothesis that dietary polyunsaturated fats have a beneficial effect on osteogenesis, reducing bone loss by decreasing chronic inflammation, and activating bone resorption through key cellular and molecular mechanisms in our aging population. We conclude that aging, obesity and a diet high in saturated fatty acids significantly impairs bone regeneration and repair and that consumption of ω-3 polyunsaturated fatty acids is associated with significantly increased bone regeneration, improved microarchitecture and structural strength. However, ω-6 polyunsaturated fatty acids were typically pro-inflammatory and have been associated with an increased fracture risk. This review suggests a potential role for ω-3 fatty acids as a non-pharmacological dietary method of reducing bone loss in our aging population. We also conclude that contemporary amendments to the formal nutritional recommendations made by the Food and Nutrition Board may be necessary such that our aging population is directly considered.

Therapeutic effect of pulsed electromagnetic field on bone wound healing in rats

This study aimed to investigate the therapeutic effect of pulsed electromagnetic field (PEMF) on bone wound in rats as a potential therapy for bone fracture-related conditions. Male rats, aged 3 months, were used to construct model of bone wounding. Wound models were randomly selected to receive PEMF therapy at 1 to 10 mT intensity. Models that did not receive PEMF therapy were used as control. The serum concentrations of calcium (Ca), phosphorus (P) and alkaline phosphatase (ALP) were determined. Bone density and biomechanical properties of callus were measured using a tensile tester. Compared with control, rats subjected to PEMF therapy had similar weight gain, but significantly higher levels of serum Ca and ALP (P < .05) at 5 and 10 mT, while the serum level of P remained unchanged after PEMF therapy. The bone mineral density of callus increased after the therapy, particularly, after 5 and 10 mT therapy (P < .05). Biomechanical measurements showed that 21 days after the therapy, the maximum load, fracture load, elastic load and bending energy were significantly greater in rats receiving 5 and 10 mT PEMF therapy as compared with control (P < .05). Our experiments demonstrate that PEMF at 5 and 10 mT can significantly accelerate wound healing and enhance the repairing ability of bone tissue.

Evaluation of pulsed electromagnetic field protocols in implant osseointegration: in vivo and in vitro study

OBJECTIVES

The present study aims to evaluate two protocols of pulsed electromagnetic field (PEMF) on osseointegration and establish one that addresses ideal parameters for its use in dentistry, especially in the optimization of the implants osseointegration process.

MATERIALS AND METHODS

Sixty male rats (Wistar) were allocated into three experimental groups: control (GC), test A (GTA, 3 h exposed), and test B (GTB, 1 h exposed). All animals received titanium implants in both tibias, and PEMF application (15 Hz, ± 1 mT, 5 days/week) occurred only in the test groups. They were euthanized at 03, 07, 21, and 45 days after PEMF therapy. Removal torque, histomorphometric measurements, three-dimensional radiographic evaluation, and in vitro biological assay analyses were performed.

RESULTS

GTB showed better results compared with GTA in removal torque tests, in bone volume and bone mineral density, cell viability, total protein content, and mineralization nodules (p < 0.05). GTA showed better performance in trabecular bone thickness and cell proliferation compared with GTB (p < 0.05), especially at osseointegration early periods. In the histomorphometric analysis and number of trabeculae, there were no differences in the test groups.

CONCLUSION

PEMF as a biostimulator was effective in optimizing the events in bone tissue that lead to osseointegration, especially when applied for a shorter time and in the initial periods of bone healing.

CLINICAL RELEVANCE

The PEMF therapy is an effective alternative method for optimizing bone healing.

Protective effect and mechanism of microRNA-146a on ankle fracture

The present study investigated the expression and role of microRNA-146a (miR-146a) on ankle fracture, and explored the underlying mechanism. miR-146a levels in the blood of patients with ankle fracture was measured using reverse transcription-quantitative PCR (RT-qPCR). Expression of pro-inflammatory factors in the peripheral blood of ankle fracture patients was also detected using ELISA. Oxidative stress biomarkers including malondialdehyde (MDA), superoxide dismutase (SOD) and catalase (CAT) were additionally investigated. The role of miR-146a in ankle fracture was investigated in vitro where MG-63 cells were transfected with miR-146a mimic or miR-146a inhibitor for 2 h, then treated with 1 µg/ml bradykinin for 24 h. An MTT assay was then performed to assess cell viability and pro-inflammatory factors were detected via RT-qPCR and western blot analysis. Finally, activation of the TNF receptor associated factor 6 (TRAF6)/NF-κB pathway was determined via western blotting and RT-qPCR. The results demonstrated that miR-146a was significantly downregulated in the blood of patients with ankle fracture. The protein levels of tumor necrosis factor (TNF-α), interleukin (IL)-1β and IL-6 were significantly upregulated in patients with ankle fracture. In addition, MDA content significantly increased, and SOD and CAT activity significantly decreased in patients with ankle fracture. In vitro experiments demonstrated that miR-146a overexpression significantly enhanced cell viability. miR-146a mimic suppressed BK-induced upregulation of TNF-α, IL-1β, IL-6 and MDA, and increased SOD and CAT activity. Finally, miR-146a mimic inhibited activation of the TRAF6/NF-κB pathway whilst miR-146a inhibitor had the opposite effect. In conclusion, miR-146a may be a potential therapeutic target for the treatment of ankle fracture by inhibiting the inflammatory response and attenuating oxidative stress.

Avicularin Reduces the Expression of Mediators of Inflammation and Oxidative Stress in Bradykinin-Treated MG-63 Human Osteoblastic Osteosarcoma Cells

BACKGROUND Avicularin is a plant-derived flavonoid used in traditional Chinese medicine to treat conditions that include ankle fracture. Bradykinin stimulated MG-63 human osteoblastic osteosarcoma cells has previously been studied in an in vitro model. This study aimed to investigate the effects of avicularin on bradykinin-treated MG-63 human osteoblastic osteosarcoma cells in vitro. MATERIAL AND METHODS MG-63 cells were treated with increasing concentrations of avicularin for 48 hours, followed by 1 μM of bradykinin for 24 h. The MTT assay was used to measure cell viability. Quantitative real-time polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA) were used to measure the expression of inflammatory mediators, interleukin-1ß (IL-1ß), IL-6, and tumor necrosis factor-alpha (TNF-alpha) mRNA and protein, respectively. The expression of oxidative stress factors, malondialdehyde (MDA), superoxide dismutase (SOD), and catalase were measured. Western blot and qRT-PCR were performed to determine p38, p65, inducible nitric oxide synthase (iNOS), and cyclooxygenase-2 (COX-2) protein levels and mRNA expression, respectively. RESULTS Avicularin had no cytotoxic effect on MG-63 cells. Avicularin significantly upregulated the expression levels IL-1ß, IL-6, and TNF-alpha in the bradykinin treated group in a dose-dependent manner. Avicularin reduced the level of MDA and the activity of SOD and catalase in the bradykinin treated MG-63 cells, reduced p-p38, p-p65, iNOS, and COX-2 expression, and decreased the p-p38/p38 ratio and the p-p65/p65 ratio in bradykinin treated MG-63 cells in a dose-dependent manner. CONCLUSIONS Avicularin reduced the expression of inflammatory cytokines and the levels of markers of oxidative stress in MG-63 human osteoblastic osteosarcoma cells in vitro.

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

Osteoporosis, fractures, and other bone diseases or injuries represent serious health problems in modern society. A variety of treatments including drugs, surgeries, physical therapies, etc. have been used to prevent or delay the progression of these diseases/injuries with limited effects. Electromagnetic field (EMF) has been used to non-invasively treat bone diseases, such as fracture and osteoporosis, for many years. However, because a variety of cellular and molecular events can be affected by EMF with various parameters, the precise bioeffects and underlying mechanisms of specific EMF on bone cells are still obscure. Here, we summarize the common therapeutic parameters (frequency and intensity) of major types of EMF used to treat bone cells taken from 32 papers we selected from the PubMed database published in English from 1991 to 2018. Briefly, pulse EMF promotes the proliferation of osteoblasts when its frequency is 7.5-15 Hz or 50-75 Hz and the intensity is 0.40-1.55 mT or 3.8-4 mT. Sinusoidal EMF, with 0.9-4.8 mT and 45-60 Hz, and static magnetic field with 0.1-0.4 mT or 400 mT, can promote osteoblast differentiation and maturation. Finally, we summarize the latest advances on the molecular signaling pathways influenced by EMF in osteoblasts and osteoclasts. A variety of molecules such as adenosine receptors, calcium channels, BMP2, Notch, Wnt1, etc., can be influenced by EMF in osteoblasts. For osteoclasts, EMF affects RANK, NF-κB, MAPK, etc. We speculate that EMF with different frequencies and intensities exert distinct bioeffects on specific bone cells. More high-quality work is required to explore the detailed effects and underlying mechanisms of EMF on bone cells/skeleton to optimize the application of EMF on bone diseases/injuries. Bioelectromagnetics. 2020;41:263-278 © 2020 Bioelectromagnetics Society.

Translational Insights into Extremely Low Frequency Pulsed Electromagnetic Fields (ELF-PEMFs) for Bone Regeneration after Trauma and Orthopedic Surgery

The finding that alterations in electrical potential play an important role in the mechanical stimulation of the bone provoked hype that noninvasive extremely low frequency pulsed electromagnetic fields (ELF-PEMF) can be used to support healing of bone and osteochondral defects. This resulted in the development of many ELF-PEMF devices for clinical use. Due to the resulting diversity of the ELF-PEMF characteristics regarding treatment regimen, and reported results, exposure to ELF-PEMFs is generally not among the guidelines to treat bone and osteochondral defects. Notwithstanding, here we show that there is strong evidence for ELF-PEMF treatment. We give a short, confined overview of in vitro studies investigating effects of ELF-PEMF treatment on bone cells, highlighting likely mechanisms. Subsequently, we summarize prospective and blinded studies, investigating the effect of ELF-PEMF treatment on acute bone fractures and bone fracture non-unions, osteotomies, spinal fusion, osteoporosis, and osteoarthritis. Although these studies favor the use of ELF-PEMF treatment, they likewise demonstrate the need for more defined and better controlled/monitored treatment modalities. However, to establish indication-oriented treatment regimen, profound knowledge of the underlying mechanisms in the sense of cellular pathways/events triggered is required, highlighting the need for more systematic studies to unravel optimal treatment conditions.

Novel magnetic stimulation methodology for low-current implantable medical devices

Recent studies highlight the ability of inductive architectures to deliver therapeutic magnetic stimuli to target tissues and to be embedded into small-scale intracorporeal medical devices. However, to date, current micro-scale biomagnetic devices require very high electric current excitations (usually exceeding 1 A) to ensure the delivery of efficient magnetic flux densities. This is a critical problem as advanced implantable devices demand self-powering, stand-alone and long-term operation. This work provides, for the first time, a novel small-scale magnetic stimulation system that requires up to 50-fold lower electric current excitations than required by relevant biomagnetic technology recently proposed. Computational models were developed to analyse the magnetic stimuli distributions and densities delivered to cellular tissues during in vitro experiments, such that the feasibility of this novel stimulator can be firstly evaluated on cell culture tests. The results demonstrate that this new stimulative technology is able to deliver osteogenic stimuli (0.1-7 mT range) by current excitations in the 0.06-4.3 mA range. Moreover, it allows coil designs with heights lower than 1 mm without significant loss of magnetic stimuli capability. Finally, suitable core diameters and stimulator-stimulator distances allow to define heterogeneity or quasi-homogeneity stimuli distributions. These results support the design of high-sophisticated biomagnetic devices for a wide range of therapeutic applications.

The cellular effects of Pulsed Electromagnetic Fields on osteoblasts: A review

Electromagnetic fields (EMFs) have long been known to interact with living organisms and their cells and to bear the potential for therapeutic use. Among the most extensively investigated applications, the use of Pulsed EMFs (PEMFs) has proven effective to ameliorate bone healing in several studies, although the evidence is still inconclusive. This is due in part to our still-poor understanding of the mechanisms by which PEMFs act on cells and affect their functions and to an ongoing lack of consensus on the most effective parameters for specific clinical applications. The present review has compared in vitro studies on PEMFs on different osteoblast models, which elucidate potential mechanisms of action for PEMFs, up to the most recent insights into the role of primary cilia, and highlight the critical issues underlying at least some of the inconsistent results in the available literature. Bioelectromagnetics. 2019;9999:XX-XX. © 2019 Bioelectromagnetics Society.

Low‑frequency pulsed electromagnetic field inhibits RANKL‑induced osteoclastic differentiation in RAW264.7 cells by scavenging reactive oxygen species

Bone homeostasis is a dynamic balance maintained by bone formation and resorption. An increase in the number and activity of osteoclasts leads to excessive bone resorption, which in turn results in bone disease, including osteoporosis. Therefore, inhibiting the differentiation and activity of osteoclasts is important for maintaining bone mass. Several studies have revealed that the use of a low-frequency pulsed electromagnetic field (PEMF) is an effective method to treat osteoporosis. However, its exact mechanism remains to be fully clarified. Therefore, the present study was designed to examine the effects that PEMF exerts on receptor activator of nuclear factor-κB ligand (RANKL)-induced osteoclastogenesis and intracellular reactive oxygen species (ROS) production in RAW264.7 cells. The viability of cells was determined using a Cell Counting Kit-8 assay, and gene and protein expression were investigated via reverse transcription-quantitative polymerase chain reaction and western blot analyses. Furthermore, microscopy was performed to detect the levels of intracellular ROS and tartrate-resistant acid phosphatase (TRAP). Following the culture of RAW264.7 cells with RANKL (50 ng/ml) for 4 days (3 h/day) under PEMF (75 Hz, 1 mt) exposure, it was observed that PEMF had an inhibitory effect on RANKL-induced osteoclastic differentiation. Multinucleated osteoclast formation, the activity of TRAP and the expression of osteoclastogenesis-associated genes, including cathepsin K, nuclear factor of activated T cells cytoplasmic 1 and TRAP, were significantly reduced by PEMF. Furthermore, PEMF effectively decreased the generation of intracellular ROS during osteoclastic differentiation. In addition, the results demonstrated that ROS are the key factor in osteoclast differentiation and formation. Reducing intracellular ROS with diphenylene-iodonium chloride significantly inhibited RANKL-induced osteoclast differentiation. Taken together, the results of the present study demonstrated that PEMF may inhibit RANKL-induced osteoclastogenesis by scavenging intracellular ROS. These results may provide the groundwork for future PEMF clinical applications in osteoclast-associated bone disease.

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

The application of pulsed electromagnetic fields (PEMFs) in the prevention and treatment of osteoporosis has long been an area of interest. However, the clinical application of PEMFs remains limited because of the poor understanding of the PEMF action mechanism. Here, we report that PEMFs promote bone formation by activating soluble adenylyl cyclase (sAC), cyclic adenosine monophosphate (cAMP), protein kinase A (PKA), and cAMP response element-binding protein (CREB) signaling pathways. First, it was found that 50 Hz 0.6 millitesla (mT) PEMFs promoted osteogenic differentiation of rat calvarial osteoblasts (ROBs), and that PEMFs activated cAMP-PKA-CREB signaling by increasing intracellular cAMP levels, facilitating phosphorylation of PKA and CREB, and inducing nuclear translocation of phosphorylated (p)-CREB. Blocking the signaling by adenylate cyclase (AC) and PKA inhibitors both abolished the osteogenic effect of PEMFs. Second, expression of sAC isoform was found to be increased significantly by PEMF treatment. Blocking sAC using sAC-specific inhibitor KH7 dramatically inhibited the osteogenic differentiation of ROBs. Finally, the peak bone mass of growing rats was significantly increased after 2 months of PEMF treatment with 90 min/day. The serum cAMP content, p-PKA, and p-CREB as well as the sAC protein expression levels were all increased significantly in femurs of treated rats. The current study indicated that PEMFs promote bone formation in vitro and in vivo by activating sAC-cAMP-PKA-CREB signaling pathway of osteoblasts directly or indirectly.

A comprehensive overview on utilizing electromagnetic fields in bone regenerative medicine

Stem cells are one of the most important sources to develope  a new strategy for repairing bone lesions through tissue engineering. Osteogenic differentiation of stem cells can be affected by various factors such as biological, chemical, physiological, and physical ones. The application of ELF-EMFs has been the subject of many research in bone tissue engineering and evidence suggests that this exogenous physical stimulus can promote osteogenic differentiation in several types of  cells. The purpose of this paper is to review the current knowledge on the effects of EMFs on stem cells in bone tissue engineering studies. We recapitulated and analyzed 39 articles that were focused on the application of EMFs for bone tissue engineering purposes. We tabulated scattered information from these articles for easy use and tried to provide an overview of conducted research and identify the knowledge gaps in the field.

Pulsed electromagnetic fields modulate bone metabolism via RANKL/OPG and Wnt/β-catenin pathways in women with postmenopausal osteoporosis: A pilot study

Pulsed electromagnetic fields (PEMFs) have been proven to enhance in vitro and in vivo osteogenesis with unknown mechanism. Aim of our study was to explore whether RANKL/OPG and Wnt/β-Catenin pathways could be involved in bone response to PEMFs in a setting of postmenopausal osteoporotic women. Forty-three women (mean age 62.8 ± 4.5 yr.) were randomized into two groups. The PEMFs group received PEMFs treatment (50 min treatment session/day, 6 treatment sessions/week, for a total of 25 times), by wearing a specific gilet applied to the trunk and connected to the electromagnetic device (Biosalus, by HSD Srl, Serravalle RSM), while women assigned to control group received sham PEMFs with the same device. BSAP as bone formation and CTX as bone resorption markers, RANKL, OPG, β-Catenin, DKK-1 and sclerostin were obtained at baseline, after 30 and 60 days. In PEMFs group, BSAP levels significantly increased after 30 and 60 days while CTX concentrations decreased at day 60. RANKL levels significantly decreased after 60 days. OPG was not significantly changed, but the RANKL/OPG ratio significantly decreased at day 30. DKK-1 levels decreased, while β-catenin concentrations increased after 30 and 60 days (P < 0.05). No significant changes of calcium, phosphorus, creatinine and sclerostin were detected. In the PEMFs group, at day 30, Δsclerostin was associated with ΔRANKL/OPG ratio (r = -0.5, P = 0.03) and ΔDKK-1 was associated with Δβ-Catenin (r = -0.47, P = 0.02). In women with postmenopausal osteoporosis, our data provide evidence of a PEMFs modulation of RANKL/OPG and Wnt/β-Catenin signaling pathways able to explain the metabolic effects of PEMFs on bone.

Pulsed electromagnetic fields prevented the decrease of bone formation in hindlimb-suspended rats by activating sAC/cAMP/PKA/CREB signaling pathway

Microgravity is one of the main threats to the health of astronauts. Pulsed electromagnetic fields (PEMFs) have been considered as one of the potential countermeasures for bone loss induced by space flight. However, the optimal therapeutic parameters of PEMFs have not been obtained and the action mechanism is still largely unknown. In this study, a set of optimal therapeutic parameters for PEMFs (50 Hz, 0.6 mT 50% duty cycle and 90 min/day) selected based on high-throughput screening with cultured osteoblasts was used to prevent bone loss in rats induced by hindlimb suspension, a commonly accepted animal model to simulate the space environment. It was found that hindlimb suspension for 4 weeks led to significant decreases in femoral and vertebral bone mineral density (BMD) and their maximal loads, severe deterioration in bone micro-structure, and decreases in levels of bone formation markers and increases in bone resorption markers. PEMF treatment prevented about 50% of the decreased BMD and maximal loads, preserved the microstructure of cancellous bone and thickness of cortical bone, and inhibited decreases in bone formation markers. Histological analyses revealed that PEMFs significantly alleviated the reduction in osteoblast number and inhibited the increase in adipocyte number in the bone marrow. PEMFs also blocked decreases in serum levels of parathyroid hormone and its downstream signal molecule cAMP, and maintained the phosphorylation levels of protein kinase A (PKA) and cAMP response element-binding protein (CREB). The expression level of soluble adenylyl cyclases (sAC) was also maintained. It therefore can be concluded that PEMFs partially prevented the bone loss induced by weightless environment by maintaining bone formation through signaling of the sAC/cAMP/PKA/CREB pathway. Bioelectromagnetics. 39:569-584, 2018. © 2018 Wiley Periodicals, Inc.

Magnetic Resonance Spectroscopy for Evaluating the Effect of Pulsed Electromagnetic Fields on Marrow Adiposity in Postmenopausal Women With Osteopenia

OBJECTIVE

Pulsed electromagnetic fields (PEMFs) could promote osteogenic differentiation and suppress adipogenic differentiation in bone mesenchymal stem cells ex vivo. However, data on the effect of PEMF on marrow adiposity in humans remain elusive. We aimed to determine the in vivo effect of PEMF on marrow adiposity in postmenopausal women using magnetic resonance spectroscopy.

METHODS

Sixty-one postmenopausal women with osteopenia, aged 53 to 85 years, were randomly assigned to receive either PEMF treatment or placebo. The session was performed 3 times per week for 6 months. All women received adequate dietary calcium and vitamin D. Bone mineral density (BMD) by dual-energy x-ray absorptiometry, vertebral marrow fat content by magnetic resonance spectroscopy, and serum biomarkers were evaluated before and after 6 months of treatment.

RESULTS

A total of 27 (87.1%) and 25 (83.3%) women completed the treatment schedule in the PEMF and placebo groups, respectively. After the 6-month treatment, lumbar spine and hip BMD increased by 1.46% to 2.04%, serum bone-specific alkaline phosphatase increased by 3.23%, and C-terminal telopeptides of type 1 collagen decreased by 9.12% in the PEMF group (P < 0.05), whereas the mean percentage changes in BMD and serum biomarkers were not significant in the placebo group. Pulsed electromagnetic field treatment significantly reduced marrow fat fraction by 4.81%. The treatment difference between the 2 groups was -4.43% (95% confidence interval, -3.70% to -5.65%; P = 0.009).

CONCLUSIONS

Pulsed electromagnetic field is an effective physiotherapy in postmenopausal women, and this effect may, at least in part, regulate the amount of fat within the bone marrow. Magnetic resonance spectroscopy may serve as a complementary imaging biomarker for monitoring response to therapy in osteoporosis.

Sinomenine Regulates Inflammatory Response and Oxidative Stress via Nuclear Factor kappa B (NF-κB) and NF-E2-Related Factor 2 (Nrf2) Signaling Pathways in Ankle Fractures in Children

BACKGROUND This study aimed to investigate the effects of SIN on ankle fracture and the underlying mechanisms in MG-63 cells. MATERIAL AND METHODS qRT-PCR and ELISA assay were used to detect the mRNA and protein levels of cytokines in peripheral blood of children with or without ankle fracture. The expression and activity of antioxidant and detoxifying enzymes were detected by ELISA assay. Pretreated MG-63 cells with/without SIN were stimulated with 1 μg/ml bradykinin (BK). A CCK-8 kit was used to detect the cell viability. The cytokines produced from MG-63 cells were detected by Western blotting and qRT-PCR. Moreover, Western blotting was used to detect the levels of p-p38 and p-NF-κB (p65), and the activation level of the Nrf2 signaling pathway was examined by qRT-PCR and Western blotting. RESULTS In this study, we found that compared with the healthy children, the mRNA and protein levels of interleukin (IL)-1β, IL-6, and tumor necrosis factor-alpha (TNF-α) were significantly upregulated in children with ankle fracture. In addition, the expression and activity of antioxidant and detoxifying enzymes were imbalanced in children with ankle fracture. SIN treatment did not have a cytotoxic effect on MG-63 cells. SIN dose-dependently suppressed BK-induced upregulation of IL-1β, IL-6, TNF-α, p-p38, and p-NF-κB (p65). Furthermore, SIN dramatically inhibited oxidative stress induced by BK via balancing the expression and activity of antioxidant and detoxifying enzymes and inhibited the activation of Nrf2 signaling. CONCLUSIONS SIN might be a potential agent for the treatment of ankle fracture through reducing inflammatory response and oxidative stress.

Anti-inflammatory effect of Resolvin D1 on LPS-treated MG-63 cells

Inflammation reaction plays an important role in the pathogenesis of ankle fracture. The aim of the present study was to investigate the effect of RvD1 on the inflammatory response and underlying molecular mechanisms in MG-63 cells. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and ELISA were used to determine the mRNA and protein expression of cytokines extracted from peripheral blood in children with or without ankle fracture, respectively. MG-63 cells were pre-treated with/without RvD1 and stimulated with 1 µg/ml LPS. The cell viability was detected by MTT assay. The production of cytokines from MG-63 cells was assessed by RT-qPCR and western blot, respectively. The expression of p-p38, NF-κB (p50) and cyclooxygenase-2 (COX-2) mRNA and protein were detected by western blot and/or RT-qPCR. The levels of NLRP3, associated recruitment domain (ASC), cleaved caspase1, caspase-1 were measured by RT-qPCR and/or western blot. The levels of interleukin (IL)-1β, IL-6 and tumor necrosis factor (TNF-α) mRNA and protein were up-regulated in children with ankle fracture compared with healthy children. RvD1 treatment did not induce cytotoxicity in MG-63 cells, but it can inhibit LPS induced MG-63 cell proliferation inhibition. RvD1 was able to dose-dependently reverse LPS induced up-regulation of TNF-α, IL-1β, IL-6 mRNA and protein expression. Furthermore, the LPS induced up-regulation of p-p38, NF-κB (p50), and NLRP3, ASC, cleaved caspase-1/caspase-1, and COX-2 was dose-dependently reversed by RvD1. In conclusion, The present study demonstrated that RvD1 inhibited inflammation though inhibiting MAPKp38/NF-κB pathway and NLRP3 inflammasome expression in MG-63 cells, indicating that it may be an effective drug for the treatment of ankle fracture.

The Use of Pulsed Electromagnetic Fields to Promote Bone Responses to Biomaterials In Vitro and In Vivo

Implantable biomaterials are extensively used to promote bone regeneration or support endosseous prosthesis in orthopedics and dentistry. Their use, however, would benefit from additional strategies to improve bone responses. Pulsed Electromagnetic Fields (PEMFs) have long been known to act on osteoblasts and bone, affecting their metabolism, in spite of our poor understanding of the underlying mechanisms. Hence, we have the hypothesis that PEMFs may also ameliorate cell responses to biomaterials, improving their growth, differentiation, and the expression of a mature phenotype and therefore increasing the tissue integration of the implanted devices and their clinical success. A broad range of settings used for PEMFs stimulation still represents a hurdle to better define treatment protocols and extensive research is needed to overcome this issue. The present review includes studies that investigated the effects of PEMFs on the response of bone cells to different classes of biomaterials and the reports that focused on in vivo investigations of biomaterials implanted in bone.

Pulsed electromagnetic fields and platelet rich plasma alone and combined for the treatment of wear-mediated periprosthetic osteolysis: An in vivo study

Wear-mediated osteolysis is a common complication occurring around implanted prosthesis, which ultimately leads to bone loss with mechanical instability and the need for surgical revision. At the moment, revision surgery is the only effective treatment. The aim of this study was to assess the efficacy of pulsed electromagnetic fields (PEMFs) and platelet rich plasma (PRP), alone and in association, in a clinically relevant in vivo model of periprosthetic osteolysis. Titanium alloy pins were implanted intramedullary in distal femurs of male inbred rats and, after osseointegration, polyethylene particles were injected intra-articularly to induce osteolysis. Animals were divided in four groups of treatment: PEMFs, PRP, PEMFs + PRP and no treatment. Microtomography was performed during the course of experiments to monitor bone stock and microarchitecture. Histology, histomorphometry, immunohistochemistry and biomechanics were evaluated after treatments. Biophysical and biological stimulations significantly enhanced bone to implant contact, bone volume and bone microhardness and reduced fibrous capsule formation and the number of osteoclasts around implants. Among treatments, PEMFs alone and in association with PRP exerted better results than PRP alone. Present data suggest that biophysical stimulation, with or without the enrichment with platelet derived growth factors, might be a safe, mini-invasive and conservative therapy for counteracting osteolysis and prompting bone formation around implants.

STATEMENT OF SIGNIFICANCE

Pulsed electromagnetic fields (PEMFs) and platelet rich plasma (PRP) show anabolic and anti-inflammatory effects and they are already been used in clinical practice, but separately. To date, there are no preclinical in vivo studies evaluating their combined efficacy in periprosthetic osteolysis, in bone tissue microarchitecture and in biomechanics. The aim of the present study was to evaluate the effects of PEMFs and PRP in vivo, when administered individually and in combination in the treatment of periprosthetic wear mediated ostelysis, and in restoring the osteogenetic properties of perimplant bone tissue and its biomechanical competence. The combination of PEMFs and PRP could be employed for counteracting the ostelysis process in a conservative and non surgical manner.

Propofol Promotes Ankle Fracture Healing in Children by Inhibiting Inflammatory Response

BACKGROUND The present study aimed to investigate the potential effects of propofol on ankle fracture healing in children and the underlying molecular mechanisms. MATERIAL AND METHODS We first detected the levels of inflammatory cytokines from peripheral blood in children with or without ankle fracture using quantitative real-time polymerase chain reaction (qRT-PCR) and ELISA assay. Then, effects of propofol on inflammatory response in MG-63 cells were investigated. MG-63 cells were pre-treated with or without propofol and then stimulated with 1 μM bradykinin (BK). The productions of cytokines from MG-63 cells were determined by using qRT-PCR and Western blot assay. The expression levels of p-p38, NF-κB p-p65, NLRP3, ASC, caspase-1, and COX-2 were measured by Western blot and/or qRT-PCR. RESULTS The results showed that, compared with the healthy children, the levels of tumor necrosis factor (TNF-α), interleukin (IL)-1β, and IL-6 were significantly up-regulated in children with fractured ankles. No cytotoxicity was observed in MG-63 cells after propofol treatment. BK treatment significantly enhanced TNF-α, IL-1β, and IL-6 expression levels, and these enhancements were reduced by propofol treatment in a dose-dependent manner. Moreover, BK-induced up-regulation of p-p38, NF-κB p-p65, NLRP3, ASC, caspase-1, and COX-2 was dose-dependently down-regulated by propofol treatment. CONCLUSIONS Propofol prevents inflammation in MG-63 cells by regulating p38MAPK-NF-κB pathway, NLRP3 inflammasome, and COX-2 expression. Our findings indicate the benefits of propofol in fracture healing, and provide a more theoretical basis for the clinical treatment of fractures.

Magnetic Stimulation Therapy in Patients with COPD: A Systematic Review

Magnetotherapy (MT) is a therapeutic treatment based on the use of magnetic fields (MF) that can have an anti-inflammatory and analgesic effect. MT represents a possible treatment or an ancillary therapeutic intervention for a wide range of diseases and it is often used in the field of physiotherapeutic practices. A crucial point in the treatment of chronic obstructive pulmonary disease (COPD) patients, to counteract muscular depletion and respiratory symptoms, is represented by physiotherapy. Nevertheless, the knowledge about the application of MF as a therapeutic option in COPD patients is very limited. The purpose of the present study was to define what is currently known about the use of MF in patients with COPD. A systematic review of the literature was conducted during the month of October 2017, searching three main databases. Only those citations providing detailed informations about the use of MF to treat COPD symptoms either during an acute or a chronic phase of the disease, were selected. Following the selection process three articles were included in the final analysis. The present review focused on a total of thirty-six patients with COPD, and on the effects of the application of MF. In the majority of cases, the treatment sessions with MF were carried-out in an outpatient setting, and they differed with regard to the duration; frequency of application; dosage; intensity of the applied MF. Basing on the available informations, it seems that MF is a feasible, well tolerated, safe therapeutic option, for the treatment of motor-related COPD symptoms.

N-methyl pyrrolidone promotes ankle fracture healing by inhibiting inflammation via suppression of the mitogen-activated protein kinase signaling pathway

N-methyl pyrrolidone (NMP), a small bioactive molecule, has the potential to stimulate bone formation and inhibit osteoclast differentiation. The aim of the present study was to investigate the effect of NMP on the inflammatory response and underlying molecular mechanisms in MG-63 cells. The mRNA and protein expression of cytokines from peripheral blood in children with or without ankle fracture were determined by reverse transcription-quantitative polymerase chain reaction (RT-qPCR) and ELISA, respectively. MG-63 cells were pre-treated with/without NMP and stimulated with 1 µM bradykinin (BK). The production of cytokines from MG-63 cells was assessed by western blotting and RT-qPCR. The expression of inducible nitric oxide synthase (iNOS) and cyclooxygenase-2 (COX-2) mRNA and protein were measured using western blotting and/or RT-qPCR. Western blotting was used to examine the activation level of mitogen activated protein kinase. Compared with healthy children, levels of tumor necrosis factor (TNF-α), interleukin (IL)-1β and IL-6 mRNA and protein were upregulated in children with ankle fracture. NMP treatment did not induce cytotoxicity in MG-63 cells. The BK-induced upregulation of TNF-α, IL-1β, IL-6, iNOS and COX-2 mRNA and protein was reversed in a dose-dependent manner by NMP. Furthermore, NMP downregulated the activation of c-Jun NH2-terminal kinase and p38 pathways, but not the extracellular signal-related kinase pathway. Therefore, the results of the current study demonstrate that NMP inhibits inflammation dependent on the mitogen-activated protein kinase pathway in MG-63 cells, indicating that it may be beneficial in the healing of fractures.

Effects of pulsed electromagnetic field (PEMF) on the tensile biomechanical properties of diabetic wounds at different phases of healing

The present study investigated the effects of pulsed electromagnetic field (PEMF) on the tensile biomechanical properties of diabetic wounds at different phases of healing. Two intensities of PEMF were adopted for comparison.

We randomly assigned 111 10-week-old male streptozotocin-induced diabetic Sprague-Dawley rats to two PEMF groups and a sham control group. Six-millimetre biopsy punched full thickness wounds were made on the lateral side of their hindlimbs. The PEMF groups received active PEMF delivered at 25 Hz with intensity of either 2 mT or 10 mT daily, while the sham group was handled in a similar way except they were not exposed to PEMF. Wound tissues were harvested for tensile testing on post-wounding days 3, 5, 7, 10, 14 and 21. Maximum load, maximum stress, energy absorption capacity, Young’s modulus and thickness of wound tissue were measured.

On post-wounding day 5, the PEMF group that received 10-mT intensity had significantly increased energy absorption capacity and showed an apparent increase in the maximum load. However, the 10-mT PEMF group demonstrated a decrease in Young’s modulus on day 14. The 10-mT PEMF groups showed a significant increase in the overall thickness of wound tissue whereas the 2-mT group showed a significant decrease in the overall maximum stress of the wounds tissue.

The present findings demonstrated that the PEMF delivered at 10 mT can improve energy absorption capacity of diabetic wounds in the early healing phase. However, PEMF (both 2-mT and 10-mT) seemed to impair the material properties (maximum stress and Young’s modulus) in the remodelling phase. PEMF may be a useful treatment for promoting the recovery of structural properties (maximum load and energy absorption capacity), but it might not be applied at the remodelling phase to avoid impairing the recovery of material properties.