Pulsed electromagnetic fields accelerate apoptotic rate in osteoclasts

Low frequency‑pulsed electromagnetic fields promote osteogenic differentiation of bone marrow‑derived mesenchymal stem cells by regulating connexin 43 expression

The present study investigated the effect of connexin 43 (Cx43) on the regulation of osteogenic differentiation of rat bone marrow-derived mesenchymal stem cells (BMSCs) using low-frequency-pulsed electromagnetic fields (LPEMF). The BMSCs were isolated and cultured in vitro using adherent whole-bone marrow cultures. CCK-8 assay was used to detect the effects of LPEMF on the proliferation ability of BMSCs and alkaline phosphatase (ALP) activity and the levels of osteogenic marker genes were detected to evaluate the osteogenic ability change following LPEMF treatment. Lentiviral vector-mediated RNA interference was transfected into BMSCs to inhibit the expression of Cx43 and western blotting was used to detect Cx43 expression. The BMSCs showed the highest proliferation following LPEMF treatment at 80 Hz for 1 h. The results of ALP activity, osteogenic marker genes and Alizarin Red S staining showed that the osteogenic ability was notably increased following LPEMF treatment at 80 Hz for 1 h. Cx43 expression increased during the osteogenic differentiation of BMSCs following LPEMF treatment at 80 Hz. The enhanced osteogenic differentiation of the LPEMF-treated BMSCs were partially reversed when Cx43 expression was inhibited. LPEMF may promote the osteogenic differentiation of BMSCs by regulating Cx43 expression and enhancing osteogenic ability.

Polyvinyl Alcohol Capped Silver Nanostructures for Fortified Apoptotic Potential Against Human Laryngeal Carcinoma Cells Hep-2 Using Extremely-Low Frequency Electromagnetic Field

Purpose

: Polyvinyl alcohol-capped silver nanostructures (cAgNSs) were investigated in order to enhance the cytotoxicity, pro-apoptotic, and oxidant patterns of in human laryngeal carcinoma Hep-2 cells by employing a 50 mT electromagnetic field (LEMF) for 30 min.

Methods

Wet chemical reduction was used to synthesize the cAgNSs, and after they had been capped with polyvinyl alcohol, they were specifically examined for particle size analysis and structural morphology. To visualize how the silver may attach to the protein targets, a molecular docking study was conducted. Estimation of cytotoxicity, cell cycle progression supported by mRNA expression of three apoptotic-promoting genes and one apoptotic-resisting.

Results

Particle size analysis results were a mean particle size of 157.3±0.5 nm, zeta potential value of -29.6 mV±1.5 mV, and polydispersity index of 0.31±0.05. Significantly reduction of IC50 against Hep-2 cells by around 6-fold was concluded. Also, we obtained suppression of the proliferation of Hep-2 cells, especially in the G0/G1 and S phases. Significant enhanced mRNA expression revealed enhanced induced CASP3, p53, and Beclin-1 mediated pro-apoptosis and induced NF-κB mediated autophagy in Hep-2 cells. Augmented levels of GR, ROS and MDA as oxidative stress biomarkers were also obtained. HE staining of Hep-2 cells exposed to cAgNSs and LEMF confirmed the enhanced apoptotic potential comparatively.

Conclusion

By conclusion, the developed nano-sized structures with the aid of extremely-low frequency electromagnetic field were successful to fortify the anti-cancer profile of cAgNSs in Hep-2 cells.

Multifunctional coatings of nickel-titanium implant toward promote osseointegration after operation of bone tumor and clinical application: a review

Metal implants, especially Ni-Ti shape memory alloy (Ni-Ti SMA) implants, have increasingly become the first choice for fracture and massive bone defects after orthopedic bone tumor surgery. In this paper, the internal composition and shape memory properties of Ni-Ti shape memory alloy were studied. In addition, the effects of porous Ni-Ti SMA on osseointegration, and the effects of surface hydrophobicity and hydrophilicity on the osseointegration of Ni-Ti implants were also investigated. In addition, the effect of surface coating modification technology of Ni-Ti shape memory alloy on bone bonding was also studied. Several kinds of Ni-Ti alloy implants commonly used in orthopedic clinic and their advantages and disadvantages were introduced. The surface changes of Ni-Ti alloy implants promote bone fusion, enhance the adhesion of red blood cells and platelets, promote local tissue regeneration and fracture healing. In the field of orthopaedics, the use of Ni-Ti shape memory alloy implants significantly promoted clinical development. Due to the introduction of the coating, the osseointegration and biocompatibility of the implant surface have been enhanced, and the success rate of the implant has been greatly improved.

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.

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.

Diamagnetic Therapy in a Patient with Complex Regional Pain Syndrome Type I and Multiple Drug Intolerance: A Case Report

Complex regional pain syndrome (CRPS) is a neurologic chronic pain condition hard to diagnose and treat, and able to significantly impact the quality of life. Currently, the available multimodal, individualized treatments (i.e., pharmacological and non-pharmacological therapies including invasive procedures) are aimed only at symptom control. Herein, we report a 69-year-old Caucasian female who came to our attention due to a 3-year history of severe (10/10) burning pain in her right ankle, along with oedema and local changes in skin color and temperature, which occurred after the ankle sprain. Previous pharmacological attempts failed due to multiple drug intolerance. Clinical examination confirmed the CRPS type I diagnosis, and a weekly diamagnetic therapy protocol was started since the patient refused further medications and interventional procedures. After 10 weeks of treatment, a significant (p < 0.01) reduction in pain severity and absence of oedema (difference in ankles’ circumference: from 3 cm to 0) were observed, with consequent improvements in quality of life and no adverse events. Although high-quality clinical evidence is still lacking, our case report suggests further investigating the potential use of diamagnetic therapy as a non-invasive and safe adjunctive treatment for CRPS, and as an alternative when patients did not benefit from drugs and/or refuse invasive procedures.

An Extremely Low-Frequency Vortex Magnetic Field Modifies Protein Expression, Rearranges the Cytoskeleton, and Induces Apoptosis of a Human Neuroblastoma Cell Line

Homogeneous extremely low-frequency electromagnetic fields (ELF-EMFs) alter biological phenomena, including the cell phenotype and proliferation rate. Heterogenous vortex magnetic fields (VMFs), a new approach of exposure to magnetic fields, induce systematic movements on charged biomolecules from target cells; however, the effect of VMFs on living systems remains uncertain. Here, we designed, constructed, and characterized an ELF-VMF-modified Rodin's coil to expose SH-SY5Y cells. Samples were analyzed by performing 2D-differential-gel electrophoresis, identified by MALDI-TOF/TOF, validated by western blotting, and characterized by confocal microscopy. A total of 106 protein spots were differentially expressed; 40 spots were downregulated and 66 were upregulated in the exposed cell proteome, compared to the control cell proteome. The identified spots are associated with cytoskeleton and cell viability proteins, and according to the protein-protein interaction network, a significant interaction among them was found. Our data revealed a decrease in cell survival associated with apoptotic cells without effects on the cell cycle, as well as evident changes in the cytoskeleton. We demonstrated that ELF-VMFs, at a specific frequency and exposure time, alter the cell proteome and structurally affect the target cells. This is the first report showing that VMF application might be a versatile system for testing different hypotheses in living systems, using appropriate exposure parameters.© 2022 Bioelectromagnetics Society.

The Effect of Abnormal Iron Metabolism on Osteoporosis

Iron is one of the important trace elements in life activities. Abnormal iron metabolism increases the incidence of many skeletal diseases, especially for osteoporosis. Iron metabolism plays a key role in the bone homeostasis. Disturbance of iron metabolism not only promotes osteoclast differentiation and apoptosis of osteoblasts but also inhibits proliferation and differentiation of osteoblasts, which eventually destroys the balance of bone remodeling. The strength and density of bone can be weakened by the disordered iron metabolism, which increases the incidence of osteoporosis. Clinically, compounds or drugs that regulate iron metabolism are used for the treatment of osteoporosis. The goal of this review summarizes the new progress on the effect of iron overload or deficiency on osteoporosis and the mechanism of disordered iron metabolism on osteoporosis. Explaining the relationship of iron metabolism with osteoporosis may provide ideas for clinical treatment and development of new drugs.

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.

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.

Pulsed electromagnetic fields: promising treatment for osteoporosis

Osteoporosis (OP) is considered to be a well-defined disease which results in high morbidity and mortality. In patients diagnosed with OP, low bone mass and fragile bone strength have been demonstrated to significantly increase risk of fragility fractures. To date, various anabolic and antiresorptive therapies have been applied to maintain healthy bone mass and strength. Pulsed electromagnetic fields (PEMFs) are employed to treat patients suffering from delayed fracture healing and nonunions. Although PEMFs stimulate osteoblastogenesis, suppress osteoclastogenesis, and influence the activity of bone marrow mesenchymal stem cells (BMSCs) and osteocytes, ultimately leading to retention of bone mass and strength. However, whether PEMFs could be taken into clinical use to treat OP is still unknown. Furthermore, the deeper signaling pathways underlying the way in which PEMFs influence OP remain unclear.

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.

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.

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

Pulsed electromagnetic fields (PEMFs) can be effective in promoting the healing of delayed union or nonunion fractures. We previously reported that PEMF (Spinal-Stim® by Orthofix, Inc., Lewisville, TX) stimulated proliferation, differentiation and mineralization of rat calvarial osteoblastic cells in culture. In the present work we investigated the effects of PEMF (Physio-Stim® by Orthofix, Inc., Lewisville, TX) on human bone marrow macrophages (hBMMs) differentiated to osteoclasts. PEMF had striking inhibitory effects on formation of osteoclasts from hBMMs from both younger and older women. There were significantly greater changes in gene expression as ascertained by RNAseq from cells from older women. Interestingly, all of the genes identified by RNAseq were upregulated, and all were genes of mesenchymal or osteoblastic cells and included members of the TGF-β signaling pathway and many extracellular matrix proteins, as well as RANKL and osteoprotegerin, indicating the mixed nature of these cultures. From these results, we suggest that PEMF can inhibit osteoclast formation via action on osteoblasts. Thus, PEMF may be very effective for bone mass maintenance in subjects with osteoporosis.

Percutaneous Kirschner Wire Repair of Failed Digital Arthrodesis Using Pulsed Electromagnetic Field Therapy A Case Report

A case of a repaired failed toe arthrodesis is presented. A novel and previously unreported approach using a percutaneously placed Kirschner wire coupled with a pulsed electromagnetic field achieved healing of a painful pseudoarthrosis at 54 days. With a percutaneous technique, open debridement of the failed arthrodesis site can be avoided.

Effects of pulsed electromagnetic fields and platelet rich plasma in preventing osteoclastogenesis in an in vitro model of osteolysis

Osteolysis is the main limiting cause for the survival of an orthopedic prosthesis and is accompanied by an enhancement in osteoclastogenesis and inflammation, due by wear debris formation. Unfortunately therapeutic treatments, besides revision surgery, are not available. The aim of the present study was to evaluate the effects of Pulsed Electro Magnetic Fields (PEMFs) and platelet rich plasma (PRP), alone or in combination, in an in vitro model of osteolysis. Rats peripheral blood mononuclear cells were cultured on Ultra High Molecular Weight Polyethylene particles and divided into four groups of treatments: (1) PEMF stimulation (12 hr/day, 2.5 mT, 75 Hz, 1.3 ms pulse duration); (2) 10% PRP; (3) combination of PEMFs, and PRP; (4) no treatment. Treatments were performed for 3 days and cell viability, osteoclast number, expression of genes related to osteoclastogenesis and inflammation and production of pro-inflammatory cytokines were assessed up to 14 days. PEMF stimulation exerted best results because it increased cell viability at early time points and counteracted osteoclastogenesis at 14 days. On the contrary, PRP increased osteoclastogenesis and reduced cell viability in comparison to PEMFs alone. The combination of PEMFs and PRP increased cell viability over time and reduced osteoclastogenesis in comparison to PRP alone. However, these positive results did not exceed the level achieved by PEMF alone. At longer time points PEMF could not counteract osteoclastogenesis increased by PRP. Regarding inflammation, all treatments maintained the production of pro-inflammatory cytokines at low level, although PRP increased the level of interleukin 1 beta.

Differential intensity-dependent effects of pulsed electromagnetic fields on RANKL-induced osteoclast formation, apoptosis, and bone resorbing ability in RAW264.7 cells

Pulsed electromagnetic fields (PEMF) have been proven to be effective for promoting bone mass and regulating bone turnover both experimentally and clinically. However, the exact mechanisms for the regulation of PEMF on osteoclastogenesis as well as optical exposure parameters of PEMF on inhibiting osteoclastic activities and functions remain unclear, representing significant limitations for extensive scientific application of PEMF in clinics. In this study, RAW264.7 cells incubated with RANKL were exposed to 15 Hz PEMF (2 h/day) at various intensities (0.5, 1, 2, and 3 mT) for 7 days. We demonstrate that bone resorbing capacity was significantly decreased by 0.5 mT PEMF mainly by inhibiting osteoclast formation and maturation, but enhanced at 3 mT by promoting osteoclast apoptosis. Moreover, gene expression of RANK, NFATc1, TRAP, CTSK, BAX, and BAX/BCL-2 was significantly decreased by 0.5 mT PEMF, but increased by 3 mT. Our findings reveal a significant intensity window for low-intensity PEMF in regulating bone resorption with diverse nature for modulating osteoclastogenesis and apoptosis. This study not only enriches our basic knowledge for the regulation of PEMF in osteoclastogenesis, but also may lead to more efficient and scientific clinical application of PEMF in regulating bone turnover and inhibiting osteopenia/osteoporosis. Bioelectromagnetics. 38:602-612, 2017. © 2017 Wiley Periodicals, Inc.

Effects of pulsed electromagnetic fields on postmenopausal osteoporosis

Postmenopausal osteoporosis (PMOP) is considered to be a well-defined subject that has caused high morbidity and mortality. In elderly women diagnosed with PMOP, low bone mass and fragile bone strength have been proven to significantly increase risk of fragility fractures. Currently, various anabolic and anti-resorptive therapies have been employed in an attempt to retain healthy bone mass and strength. Pulsed electromagnetic fields (PEMFs), first applied in treating patients with delayed fracture healing and nonunions, may turn out to be another potential and effective therapy for PMOP. PEMFs can enhance osteoblastogenesis and inhibit osteoclastogenesis, thus contributing to an increase in bone mass and strength. However, accurate mechanisms of the positive effects of PEMFs on PMOP remain to be further elucidated. This review attempts to summarize recent advances of PEMFs in treating PMOP based on clinical trials, and animal and cellular studies. Possible mechanisms are also introduced, and the future possibility of application of PEMFs on PMOP are further explored and discussed. Bioelectromagnetics. 38:406-424, 2017. © 2017 Wiley Periodicals, Inc.

Effects of electromagnetic fields on osteoporosis: A systematic literature review

Electromagnetic fields (EMFs) as a safe, effective and noninvasive treatment have been researched and used for many years in orthopedics, and the common use clinically is to promote fracture healing. The effects of EMFs on osteoporosis have not been well concerned. The balance between osteoblast and osteoclast activity as well as the balance between osteogenic differentiation and adipogenic differentiation of bone marrow mesenchymal stem cells plays an important role in the process of osteoporosis. A number of recent reports suggest that EMFs have a positive impact on the balances. In this review, we discuss the recent advances of EMFs in the treatment of osteoporosis from basic research to clinical study and introduce the possible mechanism. In addition, we presented future perspectives of application of EMFs for osteoporosis.

Effects of pulsed electromagnetic fields on bone mass and Wnt/β-catenin signaling pathway in ovariectomized rats

BACKGROUND AND AIMS

The therapeutic effects of pulsed electromagnetic fields (PEMFs) on osteoporosis have been documented. However, the precise mechanisms by which PEMFs elicit these favorable biological responses are still not fully understood. This study aimed to systematically investigate the effects of PEMFs on bone mass and Wnt/β-catenin signaling pathway in ovariectomized rats.

METHODS

Thirty 3-month-old female Sprague Dawley rats were randomly assigned to one of three groups: sham-operated control (sham), ovariectomy (OVX), and ovariectomy with PEMFs treatment (PEMFs). One week following ovariectomy surgery, rats in the PEMFs group were exposed to PEMFs for 40 min/day, 5 days/week, for 12 weeks.

RESULTS

After 12-week interventions, serum 17β-estradiol and bone-specific alkaline phosphatase levels increased in the PEMFs group. Bone mineral density of the femur and the fifth lumbar vertebral body also increased in the PEMFs group. Histomorphometrical studies showed that PEMFs improved trabecular area, trabecular width, and trabecular number by 77.50%, 17.38% and 51.06%, respectively, and reduced trabecular separation by 44.28% compared with the OVX group. Biomechanical studies showed that PEMFs increased maximum load and energy to failure in the fifth lumbar vertebral body. Quantitative real-time RT-PCR analysis showed that PEMFs increased the mRNA expressions of Wnt3a, low-density lipoprotein receptor-related protein 5(LRP5), β-catenin, c-myc and runt-related gene 2 (Runx2), and reduced dickkopf1 (DKK1) in ovariectomized rats. However, mRNA expression of Axin2 was not affected by PEMFs.

CONCLUSIONS

PEMFs can prevent ovariectomy-induced bone loss and deterioration of bone microarchitecture and strength, at least partly, through activation of Wnt/β-catenin signaling pathway.

Effects of pulsed electromagnetic fields on the mRNA expression of CAII and RANK in ovariectomized rats

The present study was designed to determine the effects of pulsed electromagnetic fields (PEMFs) on the mRNA expression of the carbonic anhydrase II (CAII) and receptor activator of NF-κB (RANK) in ovariectomized rats. A total of 48 SD rats were randomly divided into four groups [Sham, OVX, PEMFs, and E(2) (premarin)], 12 rats in each group. Rats in the Sham group received sham ovariectomy, while rats in OVX, PEMFs, and E(2) groups received ovariectomy. Twelve weeks following the surgery, rats (whole body) in the PEMFs group were exposed to PEMFs for 30 days with 3.8 mT, 8 Hz, and 40 min per day; rats in the E(2) group were administered premarin (0.0625 mg/kg/d; intragastric administration 1-2 ml/100 g). Rats in the Sham and OVX groups housed in the same conditions. At the end of intervention, the level of serum estradiol of rats was measured. The gene expression of CAII and RANK in the left ilium of rats was determined with real-time fluorescent-nested quantitative polymerase chain reaction. Compared with the Sham group, the level of serum estradiol in the ovariectomized group was significantly decreased (P < 0.05); compared with the OVX group, CAIImRNA expression was significantly decreased in the PEMFs group and E group (P < 0.05, 0.01, respectively). Compared with the E group, RANKmRNA expression was significantly higher in the PEMFs group (P < 0.05); although RANKmRNA expression decreased in PEMFs group, no statistically significant difference was found between PEMF group and OVX group (P = 0.82). These data suggest that PEMFs could regulate the expression of CAIImRNA in ovariectomized rats.

Comparison of the effects of electrical field stimulation and low-level laser therapy on bone loss in spinal cord-injured rats

OBJECTIVE

This study investigated the effects of low-level laser therapy (LLLT) and electrical stimulation (ES) on bone loss in spinal cord-injured rats.

MATERIALS AND METHODS

Thirty-seven male Wistar rats were divided into four groups: standard control group (CG); spinal cord-injured control (SC); spinal cord-injured treated with laser (SCL; GaAlAs, 830 nm, CW, 30 mW/cm, 250 J/cm(2)); and spinal cord-injured treated with electrical field stimulation (SCE; 1.5 MHz, 1:4 duty cycles, 30 mW, 20 min). Biomechanical, densitometric, and morphometric analyses were performed.

RESULTS

SC rats showed a significant decrease in bone mass, biomechanical properties, and morphometric parameters (versus CG). SCE rats showed significantly higher values of inner diameter and internal and external areas of tibia diaphyses; and the SCL group showed a trend toward the same result (versus SC). No increase was found in either mechanical or densitometric parameters.

CONCLUSION

We conclude that the mentioned treatments were able to initiate a positive bone-tissue response, maybe through stimulation of osteoblasts, which was able to determine the observed morphometric modifications. However, the evoked tissue response could not determine either biomechanical or densitometric modifications.

Efeitos dos recursos eletrofísicos na osteoporose: uma revisão da literatura

OBJETIVO: Fazer uma revisão bibliográfica a respeito dos efeitos dos principais recursos eletrofísicos utilizados na aceleração do metabolismo ósseo e no tratamento da osteoporose. ANTECEDENTES: A Organização Mundial da Saúde (OMS) define a osteoporose como doença esquelética sistêmica caracterizada por diminuição da massa óssea e deterioração microarquitetural do tecido ósseo, com consequente aumento da fragilidade óssea e susceptibilidade à fratura. Vários tratamentos medicamentosos e não medicamentosos vêm sendo desenvolvidos na tentativa de aumentar a massa óssea e prevenir a osteoporose. Dentro desse contexto, os recursos eletrofísicos vêm tendo um papel de destaque, como recursos que apresentam um potencial osteogênico, capazes de estimular a proliferação de osteoblastos e biomodular o metabolismo ósseo. ESTRATÉGIA DE PESQUISA: Foram consultadas as bases de dados: The Cochrane Library, MEDLINE, Embase, LILACS, SciELO, referências dos artigos identificados, e contato com especialisas em laser, entre os anos de 1983 e 2009. CRITÉRIOS DE SELEÇÃO: Foram incluídos estudos experimentais e ensaios clínicos randomizados que avaliaram os efeitos dos recursos eletrofísicos na osteoporose. RECOMPILAÇÃO E ANÁLISE DE DADOS: Dois revisores selecionaram independentemente os estudos, avaliaram sua qualidade metodológica dos estudos e coletaram os dados. RESULTADOS: Todos os recursos eletrofísicos citados neste artigo se mostraram eficazes na estimulação do metabolismo ósseo. No entanto, a grande maioria dos estudos realizados evidenciam esses efeitos através de estudos in vitro e estudos experimentais com cobaias. Cabe ressaltar que trabalhos como esses são raros em seres humanos. Baseado nos achados desta revisão pode ser sugerido que os recursos eletrofísicios como o laser terapêutico, o ultrassom, campos eletromagnéticos e plataformas vibratórias são recursos que tem um potencial osteogênico entretanto mais estudos são necessários para definir os efeitos dos mesmos em humanos, bem como, protocolos mais eficazes de tratamento. CONCLUSÃO: A partir deste levantamento bibliográfico, fica evidente que os recursos eletrofísicos apresentam um grande potencial osteogênico, porém, a maior parte dos estudos é in vitro. São necessários mais estudos in vivo, definindo, assim, melhores parâmetros e doses, para que sejam utilizados no tratamento da osteoporose.

Effects of pulsed electromagnetic fields on the mRNA expression of RANK and CAII in ovariectomized rat osteoclast-like cell

This study was designed to determine the effects of pulsed electromagnetic fields (PEMF) on the mRNA expression of the receptor activator of NF-kappa-B (RANK) and carbonic anhydrase II (CA II) in ovariectomized rat osteoclast-like cells. Marrow cells were harvested from femora and tibiae of rats, from which the ovaries had been totally excised, and cultured in 6-well chamber slides. After 1 day of incubation, the marrow cells were exposed to PEMF for 3 days with 3.8 mT, 8 Hz, and 40 min per day. Osteoclast-like cells were confirmed by both tartrate resistant acid phosphatase (TRAP) stain and bone resorption assay. The expression of RANK and CA II mRNA was determined with real-time fluorescent-nested quantitative polymerase chain reaction. Compared with the sham group, the level of serum estradiol in the ovariectomized group was significantly decreased ( p < 0.05). The numbers of multinucleated, TRAP-positive osteoclast-like cells and resorption pits formed were observed. In invitro study, the expression of RANK and CA II were measured in sham, ovariectomized without PEMF, and ovariectomized with PEMF treatment. Compared with the ovariectomized (PEMF) experimental group and sham group, CA II mRNA expression was significantly increased in the ovariectomized control group ( p < 0.05, 0.01, respectively). Compared with the sham group, RANK mRNA expression was significantly increased in the ovariectomized control group ( p < 0.05). These data suggest that PEMF could regulate the expression of RANK and CA II mRNA in the marrow culture system.

Modulation of osteogenesis in human mesenchymal stem cells by specific pulsed electromagnetic field stimulation

Human mesenchymal stem cells (hMSCs) are a promising candidate cell type for regenerative medicine and tissue engineering applications by virtue of their capacity for self-renewal and multipotent differentiation. Our intent was to characterize the effect of pulsed electromagnetic fields (PEMFs) on the proliferation and osteogenic differentiation of hMSCs in vitro. hMSCs isolated from the bone marrow of adult patients were cultured with osteogenic medium for up to 28 days and exposed to daily PEMF stimulation with single, narrow 300 micros quasi-rectangular pulses with a repetition rate of 7.5 Hz. Relatively greater cell numbers were observed at late stages of osteogenic culture with PEMF exposure. The production of alkaline phosphatase (ALP), an early marker of osteogenesis, was significantly enhanced at day 7 with PEMF treatment in both basal and osteogenic cultures as compared to untreated controls. Furthermore, the expressions of other early osteogenic genes, including Runx2/Cbfa1 and ALP, were also partially modulated by PEMF exposure, indicating that osteogenesis in hMSCs was associated with the specific PEMF stimulation. Based on ALP and alizarin red S staining, the accumulation of ALP protein produced by the hMSCs as well as calcium deposits reached their highest levels at day 28. Our results indicate that extremely low-frequency PEMF stimulation may play a modulating role in hMSC osteogenesis. Taken together, these findings provide insights on the development of PEMF as an effective technology for regenerative medicine.

Effect of pulsed electromagnetic field on the proliferation and differentiation potential of human bone marrow mesenchymal stem cells

Pulsed electromagnetic fields (PEMFs) have been used clinically to slow down osteoporosis and accelerate the healing of bone fractures for many years. The aim of this study is to investigate the effect of PEMFs on the proliferation and differentiation potential of human bone marrow mesenchymal stem cells (BMMSC). PEMF stimulus was administered to BMMSCs for 8 h per day during culture period. The PEMF applied consisted of 4.5 ms bursts repeating at 15 Hz, and each burst contained 20 pulses. Results showed that about 59% and 40% more viable BMMSC cells were obtained in the PEMF-exposed cultures at 24 h after plating for the seeding density of 1000 and 3000 cells/cm2, respectively. Although, based on the kinetic analysis, the growth rates of BMMSC during the exponential growth phase were not significantly affected, 20-60% higher cell densities were achieved during the exponentially expanding stage. Many newly divided cells appeared from 12 to 16 h after the PEMF treatment as revealed by the cell cycle analysis. These results suggest that PEMF exposure could enhance the BMMSC cell proliferation during the exponential phase and it possibly resulted from the shortening of the lag phase. In addition, according to the cytochemical and immunofluorescence analysis performed, the PEMF-exposed BMMSC showed multi-lineage differentiation potential similar to the control group.

Elevation of plasma corticosterone levels and hippocampal glucocorticoid receptor translocation in rats: a potential mechanism for cognition impairment following chronic low-power-density microwave exposure

The goal of this study was to investigate whether glucocorticoids (GCs) take part in cognition impairment after exposure to chronic low-power-density microwave (MW) fields. We exposed Wistar rats to a 2.45-GHz pulsed MW field at an average power density of 1 mW/cm(2) for 3 h daily, for up to 30 days. Our results show that MW-exposed rats had significant deficits in spatial learning and memory performance. MW exposure increased levels of plasma corticosterone, and consequently GC receptor (GR) nuclear translocation and apoptosis in the hippocampus. However, co-administration of the GR antagonist RU486 with MW exposure partially reversed the cognitive impairment and neuronal loss. These data indicate that GCs might contribute to the cognition deficit induced by chronic low-power-density MW exposure.