Moderate Static Magnetic Fields Research Articles

The Effect of Static Magnetic Fields of Different Strengths and Polarities on Cytokine Production by Human Lymphocytes In Vitro.

In contrast to electromagnetic fields, static magnetic fields (SMFs) have not been extensively studied in terms of their potential health consequences. Although upward- and downward-oriented magnetic poles may cause various biological effects, only the pole with the upward orientation has been mainly investigated. Considering that the interaction of antigen-presenting cells (APCs) and T lymphocytes is crucial to trigger an immune response, we assessed the effect of long-term exposure of human T lymphocytes and dendritic cells (DCs) to moderate strength SMFs of different orientations focusing on the cytokine profile of activated T cells. Cultures of allogenic T lymphocytes and DCs (immature and matured by TLR3 and TLR7 agonists) were continuously exposed to four SMFs. The intensity of the applied field was 1 militesla (mT) or 56 mT of the upward- and downward-oriented pole of the SMF. Cell culture supernatants were assayed for IFN-γ, IL-4, IL-17, TNF-α, TNF-β, IL-1 β, IL-6, IL-8, and IL-10 by ELISA or flow cytometry. The upward-oriented 56 mT SMF significantly increased the release of IFN-γ and TNF-β (both p < 0.05) in the cell culture supernatants of T cells and immature DCs. In contrast, the same cultures exposed to the upward-oriented 1 mT SMF showed significantly elevated levels of IL-17 (p < 0.05). The levels of IL-4, TNF-α, IL-1 β, IL-6, IL-8, and IL-10 were not affected by the upward-oriented SMF. The downward-oriented 56 mT SMF increased TNF-α release when T cells were stimulated with mature DCs. The production of other cytokines was unchanged by the downward-oriented SMF. These findings demonstrate for the first time different in vitro biological effects of upward- and downward-oriented static magnetic fields on the cytokine production of T cells activated by DCs, helping to better understand SMF effects on the immune system and suggesting that the selective SMF effect on the immune response could have potential therapeutic effects in different immune-mediated disorders.

Effect of Moderate Static Magnetic Fields on Mice Oocyte Vitrification: Calcium-Related Genes Expression.

The ability to cryopreserve oocytes without ultrastructural injury has been a concern in the development and use of methods to preserve female reproduction. The stability of the cell membrane must be preserved to reduce the damage caused by ice crystals during vitrification. One approach that has been explored is the use of static magnetic fields (SMFs), which are believed to influence cell membrane stability. In this study, the in vitro effects of SMF that range between 20-80 mT on the vitrification of mice germinal vesicle (GV) oocytes were studied. The viability and mitochondrial (Mt) membrane potential of both vitrified and nonvitrified oocytes were assessed using Trypan blue and JC1 staining. The high in vitro maturation (IVM) rate and high Mt membrane potential in metaphase II (MII) oocytes were taken into account to determine the optimal magnetic field intensity, that is, 20 mT. None of the SMF conditions resulted in intact spindles in MII oocytes. The study also explored the expression of store-operated calcium entry (Stim1, Orai1, and Ip3r) and meiosis resumption (Ccnb, Cdk) genes in GV and MII oocytes of both vitrified and control groups. The results show that the expressions of Orai1 and Ccnb genes in Vit-MII-SMF oocytes were considerably increased. However, no significant difference in Stim1 expression was observed between the groups. The Vit-MII-SMF group exhibited a significantly higher Ccnb expression compared to other groups. In vitro fertilization (IVF) was performed to evaluate the 2 pronuclear (2PN) rates. The findings demonstrated that using 20 mT SMF improved 2PN rates compared to the nonvitrified groups. This study provides a deeper understanding of the effects of moderate SMF and vitrification on the expression of calcium channel genes in GV and MII oocytes. The results suggest that applying a 20 mT SMF can help prevent cryoinjury and enhance the characteristics of vitrified-warmed oocytes.

Static magnetic fields in regenerative medicine.

All organisms on Earth live in the weak but ubiquitous geomagnetic field. Human beings are also exposed to magnetic fields generated by multiple sources, ranging from permanent magnets to magnetic resonance imaging (MRI) in hospitals. It has been shown that different magnetic fields can generate various effects on different tissues and cells. Among them, stem cells appear to be one of the most sensitive cell types to magnetic fields, which are the fundamental units of regenerative therapies. In this review, we focus on the bioeffects of static magnetic fields (SMFs), which are related to regenerative medicine. Most reports in the literature focus on the influence of SMF on bone regeneration, wound healing, and stem cell production. Multiple aspects of the cellular events, including gene expression, cell signaling pathways, reactive oxygen species, inflammation, and cytoskeleton, have been shown to be affected by SMFs. Although no consensus yet, current evidence indicates that moderate and high SMFs could serve as a promising physical tool to promote bone regeneration, wound healing, neural differentiation, and dental regeneration. All in vivo studies of SMFs on bone regeneration and wound healing have shown beneficial effects, which unravel the great potential of SMFs in these aspects. More mechanistic studies, magnetic field parameter optimization, and clinical investigations on human bodies will be imperative for the successful clinical applications of SMFs in regenerative medicine.

Moderate static magnetic field promotes fracture healing and regulates iron metabolism in mice

BackgroundFractures are the most common orthopedic diseases. It is known that static magnetic fields (SMFs) can contribute to the maintenance of bone health. However, the effect and mechanism of SMFs on fracture is still unclear. This study is aim to investigate the effect of moderate static magnetic fields (MMFs) on bone structure and metabolism during fracture healing.MethodsEight-week-old male C57BL/6J mice were subjected to a unilateral open transverse tibial fracture, and following treatment under geomagnetic field (GMF) or MMF. The micro-computed tomography (Micro-CT) and three-point bending were employed to evaluate the microarchitecture and mechanical properties. Endochondral ossification and bone remodeling were evaluated by bone histomorphometric and serum biochemical assay. In addition, the atomic absorption spectroscopy and ELISA were utilized to examine the influence of MMF exposure on iron metabolism in mice.ResultsMMF exposure increased bone mineral density (BMD), bone volume per tissue volume (BV/TV), mechanical properties, and proportion of mineralized bone matrix of the callus during fracture healing. MMF exposure reduced the proportion of cartilage in the callus area during fracture healing. Meanwhile, MMF exposure increased the number of osteoblasts in callus on the 14th day, and reduced the number of osteoclasts on the 28th day of fracture healing. Furthermore, MMF exposure increased PINP and OCN levels, and reduced the TRAP-5b and β-CTX levels in serum. It was also observed that MMF exposure reduced the iron content in the liver and callus, as well as serum ferritin levels while elevating the serum hepcidin concentration.ConclusionsMMF exposure could accelerate fracture healing via promote the endochondral ossification and bone formation while regulating systemic iron metabolism during fracture healing. This study suggests that MMF may have the potential to become a form of physical therapy for fractures.

A safety study on ultra‑high or moderate static magnetic fields combined with platycodin D against lung cancer.

Due to the serious side effects of chemotherapy drugs against lung cancer, and the antitumor properties and high safety of magnetic fields, the present study combined moderate or ultra-high intensity statics magnetic fields (SMFs) with platycodin D (PD) to explore the antitumor efficiency and biosafety. The antitumor effects of PD with or without moderate and ultra-high SMFs on A549 cells bearing mice were compared. Mouse body weight, food/water intake, hematology routine, blood biochemistry, tumor weight and tissues hematoxylin and eosin (H&E) staining were examined. Behavior was measured using the elevated plus maze, open field and vital signs tests. The combined targets of PD and SMFs were detected using RNA-sequencing (RNA-seq). The results showed that the antitumor effect of 22 Tesla (T) SMF group was 3.6-fold higher compared with that of the 2 mg/kg PD group (tumor growth inhibition=10.08%), while the antitumor effect of 150 mT SMF was only 1.56-fold higher compared with that of PD. Although PD reduced the food intake, there was no significant difference in body weight, water intake or food consumption among PD and SMF groups. Behavioral results indicated that PD ameliorated dysphoria in mice, but SMFs reduced this effect. However, no significant abnormalities were found in routine blood, blood biochemistry test, H&E staining or organ index, except renal index which was reduced by PD with or without SMFs. RNA-sequencing (RNA-seq) demonstrated that SMFs and PD synergistically targeted the expression of genes associated with tumor growth, inflammation and neurological disease. The present study showed the antitumor efficacy and biosafety of moderate or ultra-high SMF combined with PD, which exhibited only few side effects in the treatment of lung cancer, thus supporting further research for the clinical application of magnetic fields.

Effects of moderate static magnetic fields on the lipogenesis and lipolysis in different genders of Caenorhabditis elegans

With the rapid development of magnetic technology, the biological effects of moderate static magnetic fields (SMFs) have attracted increasing research interest due to their potential medical diagnosis and treatment application. The present study explored the effects of moderate SMFs on the lipid metabolism of Caenorhabditis elegans (C. elegans) in different genders including male, female, and hermaphrodite. We found that the fat content was significantly decreased by moderate SMFs in wild-type N2 worms, which was associated with their development stages. The diameters of lipid droplets in N2 worms, him-5 worms, and fog-2 worms were greatly decreased by 19.23%, 15.38%, and 23.07% at young adult stage under 0.5 T SMF, respectively. The mRNA levels of lipolysis related genes atgl-1 and nhr-76 were significantly up-regulated by SMF exposure, while the mRNA levels of the lipogenesis related genes fat-6, fat-7, and sbp-1 were down-regulated by SMF, whereas the concentration of β-oxidase was increased. There was a slight effect of SMF on the mRNA levels of β-oxidation related genes. Moreover, the insulin and serotonin pathway were regulated by SMF, instead of the TOR pathway. In wild-type worms, we found that their lifespan was prolonged by exposure to 0.5 T SMF. Our data suggested that moderate SMFs could significantly modify the lipogenesis and lipolysis process in C. elegans in a gender and development stage-dependent manner, which could provide a novel insight into understanding the function of moderate SMFs in living organisms.

Magnetic Fields Affect Alcoholic Liver Disease by Liver Cell Oxidative Stress and Proliferation Regulation.

It is well known that alcohol consumption leads to substantially increased free radical levels and health risks, which lacks effective treatment besides alcohol abstinence. Here, we compared different static magnetic field (SMF) settings and found that a downward quasi-uniform SMF of ~0.1 to 0.2 T could effectively alleviate alcohol-induced liver damage and lipid accumulation and improve hepatic function. SMFs of two different directions can reduce the inflammation, reactive oxygen species levels, and oxidative stress in the liver, while the downward SMF had more obvious effects. Moreover, we found that the upward direction SMF of ~0.1 to 0.2 T could inhibit DNA synthesis and regeneration in hepatocytes, which caused detrimental effects on the lifespan of "heavy drinking" mice. In contrast, the downward SMF prolongs survival of "heavy drinking" mice. On one hand, our study shows that ~0.1 to 0.2 T moderate quasi-uniform SMFs with a downward direction have great promises to be developed into a physical method to reduce alcohol-induced liver damage; on the other hand, although the internationally recognized upper limit for SMF public exposure is 0.4 T, people should also pay extra attention to SMF strength, direction, and inhomogeneity that could generate harmful effects on specific severe pathological conditions.

Effect of Moderate Static Magnetic Field on Membrane Potential of Abdominal Nerve Fiber in Metapenaeus Ensis

Effect of Moderate Static Magnetic Field on Membrane Potential of Abdominal Nerve Fiber in <i>Metapenaeus Ensis</i>

Directional solidification of A356 aluminium alloy under the interaction of DC magnetic field and electric current

This article describes an experimental investigation and results of electromagnetic (EM) interaction during the continuous casting of the silicon-rich aluminum alloy A356. Directional solidification of aluminum rods with a diameter of 10 to 12 mm under the interaction of a moderate static magnetic field of 0.45 T and an applied DC electric current has been studied. The developed EM interaction drives a small-scale molten metal flow directly in the mushy zone, which impacts the heat and solute transport. However, this affects the microstructure and, in the end, the properties of the alloy. Tables 3, Figs 23, Refs 23.

Life on Magnet: Long-Term Exposure of Moderate Static Magnetic Fields on the Lifespan and Healthspan of Mice.

All living organisms on the Earth live and evolve in the presence of the weak geomagnetic field, a quasi-uniform static magnetic field (SMF). In the meantime, although the effects of moderate and high SMFs have been investigated on multiple aspects of a living organism, a long-term SMF exposure of more than 1 year has never been reported. Here, we investigated the influence of a moderate SMF (70-220 mT head-to-toe) long-term continuous exposure (1.7 years) to two different SMF directions on healthy male C57BL/6 mice. We found that not only was the lifespan of the mice prolonged, but their healthspan was also improved. The elevated plus maze test and open field test show that SMFs could significantly improve the exploratory and locomotive activities of the aged mice. The Morris water maze test shows that SMFs could improve their spatial learning ability and spatial memory. Tissue examinations reveal that SMFs have an ameliorative effect on oxidative stress in the brain of aged mice, which was reinforced by the cellular assays, showing that SMFs could protect the PC12 cells from D-gal-induced senescence by increasing superoxide dismutase, catalase, and reducing the malonaldehyde levels. Therefore, our data show that the 1.7-year SMF exposure can improve both the lifespan and healthspan of naturally aged mice due to reduced oxidative stress, which indicates that SMFs have the potential to be used as an adjuvant physical therapy to reduce the ageing-induced health risks to benefit animals, and even humans.

Static Magnetic Fields Protect against Cisplatin-Induced Kidney Toxicity.

Cisplatin is one of the most widely used anti-cancer drugs that can effectively inhibit the growth of multiple types of cancer. However, its clinical application is limited by its severe side effects, especially kidney toxicity, caused by cisplatin-induced oxidative stress, inflammation and kidney cell apoptosis. Here, we found that moderate (a few hundred mT) quasi-uniform static magnetic fields (SMFs) could inhibit cisplatin-induced renal proximal tubular cell death, especially the vertically downward direction SMF. RNA-seq experiments demonstrate that SMFs induced differential gene expressions that are closely associated with oxidative stress, apoptosis, cytokine production, transmembrane transport and DNA repair. In vivo experiments show that SMFs can reduce cisplatin-induced kidney injury in cisplatin-administrated tumor-bearing mice by reducing oxidative stress, inflammation and cell apoptosis. Furthermore, high-dose cisplatin-induced acute nephrotoxicity can be effectively alleviated by SMF treatment of as little as one day, which significantly reduced the reactive oxygen species levels in kidneys and prolonged the mice's survival. Moreover, the concentration of cisplatin in the kidney was significantly attenuated in SMF-treated mice. Therefore, our study demonstrates the effects of moderate SMFs as a novel physical method to reduce oxidative stress, and revealed their future potential to be used against cisplatin-induced kidney toxicity in cancer treatment.

The Effect of Long-Term Moderate Static Magnetic Field Exposure on Adult Female Mice.

Because of the high cost and safety of ultra-high magnetic resonance imaging (MRI), its application has certain limitations. Whereas 0.5-3 T MRI has been widely applied in hospitals, static magnetic fields (SMFs) have been shown to improve mice mental health and have anti-tumor potentials. Here, we compared the effects of the upward and downward 150 mT SMF groups with the sham group on C57BL/6J adult female mice. Locomotor and exploratory activity were also measured by behavioral tests, including the open field and elevated plus test. Additionally, physiology, pathology indicators and gut microbiota were examined. We found that 150 mT SMFs long-term exposure enhanced locomotive and exploratory activity of mice, especially the downward 150 mT SMF. Compared with the downward 150 mT SMF group, the movement speed and distance in the center area of the sham group were increased by 65.99% (p &lt; 0.0001) and 68.58% (p = 0.0038), respectively. Moreover, compared to the sham group, downward 150 mT SMF increased the number of entrances to the center area by 67.0% (p = 0.0082) and time in the center area by 77.12% (p = 0.0054). Additionally, we observed that upward 150 mT SMF improved the number of follicles (~2.5 times, p = 0.0325) and uterine glands through increasing the total antioxidant capacity and reducing lipid peroxidation level in mice. Gut microbiome analysis showed that 150 mT SMFs long-term exposure improved the microbiota abundance (Clostridium, Bifidobacterium, Ralstonia and Yaniella) in the genus level, which may affect metabolism, anxiety and behavior in adult female mice. Our results demonstrated that 150 mT SMFs long-term exposure not only had good biosafety, but also improved athletic performance, emotion and the function of ovarian, uterine and gut microbiota abundance in adult female mice, which unraveled the potential of moderate long-term SMF exposure in clinical applications.

A moderate static magnetic field promotes C. elegans longevity through cytochrome P450s

Ageing is co-regulated by genetic and environmental factors. Life on earth lives and evolves in a mild geomagnetic field. Yet, the biological effects of a moderate magnetic field on ageing and the underlying genetic mechanisms remain barely unknown. Here, we report that a moderate static magnetic field (SMF) extends the lifespan of Caenorhabditis elegans, a well-established model organism in ageing research. Consistently, the SMF-treated worms show improved motility and mitochondrial function when aged. We identified from the transcriptomic changes upon SMF treatment that the upregulation of three cytochrome P450 genes are required for SMF-induced longevity. Our findings thus reveal that proper SMF treatment could promote longevity through the well-conserved cytochrome P450 enzymes.

Static magnetic field modulates olfactory ensheathing cell's morphology, division, and migration activities, a biophysical approach to regeneration.

The moderate static magnetic fields (SMFs) have been used here as a non-invasive tool to study their manipulative effects on the olfactory ensheathing cells (OECs) activity, growth, morphology, and migration in culture. The OECs are involved in the regeneration of primary olfactory sensory neurons and migration into the central nervous system to repair axons damaged by infection, injury, etc., that play a pivotal role in complementary regenerative medicine. Here, OECs were isolated from the olfactory bulb and cultured to confluence. An in vitro wound healing model was formed and exposed to either parallel (PaSMF) or perpendicular (PeSMF) SMF at intensities of 30, 50, and 70mT, and cells' morphology, podia formation, proliferation, and migration were studied by time-lapse recording. The SMFs were not cytotoxic at the intensity and exposure time applied here. The exposure of cells to 70mT PaSMF and PeSMF increased the formation of lamellipodia and filopodia, cell migration speed, and direction of the scratch forefront cells, significantly. Treatment of cells with 70mT PaSMF and PeSMF increased cell divisions, while 30mT PaSMF decreased it. SMF effects on OECs division, motility, migratory direction, and velocity indicate its effect on various aspects of cell physiology and signaling at atomic and molecular levels, and have a role in tissue regeneration that involves microtubules and actin filaments formation and rearrangements. Thus, the exposure of OECs with moderate SMF might be considered a promising noninvasive approach to remotely manipulate normal and stem cell activities for therapeutic regenerative purposes in various tissues including the central nervous system.

Moderate intensity of static magnetic fields can alter the avoidance behavior and fat storage of Caenorhabditis elegans via serotonin.

Man-made static magnetic fields (SMFs) widely exist in human life as a physical environmental factor.However, the biological responses to moderate SMFs exposure and their underlying mechanisms are largely unknown. The present study was focused on exploring the nervous responses to moderate-intensity SMFs at 0.5T and 1T in Caenorhabditis elegans (C. elegans). We found that SMFs at either 0.5T or 1T had no statistically significant effects on the locomotor behaviors, while the 1T magnetic field increased pharyngeal pumping. The avoidance behavior of the pathogenic Pseudomonas aeruginosa was greatly decreased in either 0.5T or 1T SMFs exposed nematodes, and the learning index was reducede from 0.52 ± 0.11 to 0.23 ± 0.17 and 0.16 ± 0.11, respectively. The total serotonin level was increased by 17.08% and 16.45% with the treatment of 0.5T and 1T SMF, compared to the control group; however, there were minimal effects of SMFs on other three neurotransmitters including choline, γ-aminobutyric acid (GABA), dopamine. RT-qPCR was used to further investigate the expression of serotonin-related genes, including rate-limiting enzymes, transcription factors and transport receptors. The expression levels of tph-1 and unc-86 genes were increased by SMF exposure, while those of ocr-2, osm-9, ser-1 and mod-1 genes were decreased. With the staining of lipid in either wild-type N2 or tph-1 mutants, we found that 0.5T and 1T SMFs decreased fat storage in C. elegans via serotonin pathway. Our study demonstrated that moderate-intensity SMFs induced neurobehavioral disorder and the reduction of fat storage by disturbing the secretion of serotonin in C. elegans, which provided new insights into elucidating nervous responses of C. elegans to moderate-intensity SMFs.

Novel static magnetic field effects on green chemistry biosynthesis of silver nanoparticles in Saccharomyces cerevisiae

The bacteriocidal properties of silver nanoparticles (AgNPs) depend on their average diameter (toxicity increases with decreasing diameter). In the present work, we describe novel green chemistry biosynthesis of AgNPs from AgNO3 added to cell-free culture medium of baker’s yeast, Saccharomyces cerevisiae, yielding nanoparticles in the range 11–25 nm. However, when yeast was grown in a moderate static magnetic field, AgNPs obtained from the resulting cell-free culture medium, were significantly smaller (2–12 nm) than those obtained without magnetic field. These latter nanoparticles were highly crystalline, stable and near-uniform shape. Furthermore, the antibacterial activity of AgNPs obtained from static magnetic fields were greater than those from control cultures. Static magnetic fields show a promising ability to generate biocidal nanoparticles via this novel green chemistry approach.

Effect of magnetic graphene oxide on cellular behaviors and osteogenesis under a moderate static magnetic field

The biological behaviors of magnetic graphene oxide (MGO) in a static magnetic field (SMF) are unknown. The current study is to investigate the cellular behaviors, osteogenesis and the mechanism in BMSCs treated with MGO combined with an SMF. Results showed that the synthetic MGO particles were bio-compatible and could significantly improve the osteogenesis of BMSCs under SMFs, as verified by elevated alkaline phosphatase activity, mineralized nodule formation, and expressions of mRNA and protein levels. Under SMF at the same intensity, the addition of graphene oxide to Fe3O4 could increase the osteogenic ability of BMSCs. The Wnt/β-catenin pathway was indicated to be related to the MGO-driven osteogenic behavior of the BMSCs under SMF. Taken together, our findings suggested that MGO under an SMF could promote osteogenesis in BMSCs through the Wnt/β-catenin pathway and hence should attract more attention for practical applications in bone tissue regeneration.

EFFECT OF MODERATE STATIC MAGNETIC FIELD ON HUMAN BONE MARROW MESENCHYMAL STEM CELLS: A PRELIMINARY STUDY FOR REGENERATIVE MEDICINE

Static Magnetic Field (SMF) is one of the biophysiological stimulants which modulates physiological processes in different cell lines. Mesenchymal stem cells (MSCs) are important biological tools for regenerative medicine. Although it is known that SMFs cause a change in cellular membrane polarization, oxidative product concentrations, gene expression patterns and cell propagation rates, depending on exposure time and intensity, their effects on MSCs have not been properly explained yet. In this study, MSCs derived from human bone marrow were treated with moderate 328 mT SMF by using cylindric Neodymium Iron Boron (Nd2Fe14B) magnets to investigate its influence on orientation, proliferation rates and morphologies. Results showed that the treated cells gained more homogenous orientation than the non-treated cells, however SMF influence did not significantly change proliferation rates. The cells were grown under both chemically osteogenic induction and SMF to observe the osteogenic differentiation and biomineralization. Alkaline phosphatase (ALP) activity decreased significantly in the cells treated with SMF compared to the control groups. Alizarin Red S staining showed that mineralization also decreased in the cells. The results showed that an easily produced moderate SMF can be a useful physical stimulant to control the fate of MSC both in vitro and in vivo.

Moderate Static Magnetic Fields Prevent Bone Architectural Deterioration and Strength Reduction in Ovariectomized Mice

Substantial studies have revealed the capacity of moderate-intensity static magnetic fields (SMFs) on promoting osteogenesis and inhibiting bone resorption. However, it is unknown whether moderate SMF can resist the deterioration of bone microarchitecture and strength induced by the reduction of estrogen in animal model for postmenopausal osteoporosis. Herein, the efficiency of moderate SMF of 0.2~0.4 T and SMF of 0.6 T on bone mineral density (BMD) and bone mineral content (BMC), bone microarchitecture, bone strength, and histological bone turnover was systematically investigated in ovariectomized (OVX) mice. OVX mice and sham mice were subjected to SMF exposure continuously for four weeks. Dual-energy X-ray absorptiometry (DEXA) data showed SMF prevented the reduction of BMD and BMC in OVX mice. Micro-computed tomography (Micro-CT) results revealed that SMF ameliorated the deterioration of trabecular and cortical bone microarchitecture. Three-point bending test showed that SMF mitigated OVX-induced reduction in femoral mechanical properties, including stiffness, ultimate stress, and elasticity modulus. Moreover, bone histochemical analysis demonstrated that SMF decreased osteoclast formation in cancellous bone and cortical bone, while SMF increased osteoblast formation in trabecular bone. Together, these results demonstrate that moderate SMF alleviated menopause-induced bone loss effectively, and imply that moderate SMF might become a potential biophysical treatment modality for postmenopausal osteoporosis.

Static Magnetic Field (2–4 T) Improves Bone Microstructure and Mechanical Properties by Coordinating Osteoblast/Osteoclast Differentiation in Mice

Static magnetic field (SMF), with constant magnetic field strength and direction, has a long history of basic and clinical research in bone biology. Numerous studies demonstrate that exposure to moderate SMF (1 mT-1 T) can increase bone mass and bone density. However, few studies pay attention to the effects of high SMF (>1 T) on the skeletal system. To investigate the physiological effects of high SMF on bone, mice were exposed to 2-4 T SMF for 28 days. Bone microstructure and mechanical properties were examined. The activity of osteoblasts and osteoclasts involved in bone remodeling was evaluated in vivo and in vitro. Compared with the unexposed group, 2-4 T significantly improved the femoral microstructure and tibial mechanical properties. For bone remodeling in vivo, the number of osteoblasts and bone formation was increased, and the osteoclastic number was decreased by 2-4 T. Moreover, the expression of marker proteins in the femur and concentrations of biochemical indicators in serum involved in bone formation were elevated and bone resorption was reduced under 2-4 T SMF. In vitro, osteoblast differentiation was promoted, and the osteoclastic formation and bone resorption ability were inhibited by 2 T SMF. Overall, these results demonstrate that 2-4 T SMF improved bone microarchitecture and strength by stimulating bone formation and restraining bone resorption, and imply that high SMF might become a potential biophysical treatment modality for bone diseases with abnormal bone remodeling. Bioelectromagnetics. © 2021 Bioelectromagnetics Society.