Magnetic fields at extremely low-frequency (50Hz, 0.8mT) can induce the uptake of intracellular calcium levels in osteoblasts

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.

Effects of extremely low frequency electromagnetic fields on the tumor cell inhibition and the possible mechanism

Low-frequency magnetic fields exert a significant inhibitory effect on tumor growth and have been developed as a therapeutic modality. However, the effect of a low-frequency magnetic field on the interaction between cells is still poorly understood. This study aimed to preliminarily evaluate the direct effect of magnetic field ditectely on cultured cells and indirect effect mediated by cell-environment (conditioned medium). 293 T cells, Hepg2 cells, A549 cells have been cultured at 37 ± 0.18 °C in presence of an extremely low-frequency magnetic field of 20 Hz, 5-mT. The adherent tumor cells were more sensitive to magnetic field inhibition in the original environment (conditioned medium) with adherence inhibition rate for Hepg2 and A549 estimated at 18% and 30% respectively. The inhibition effect was suppressed when the suspended cells separated or clump density at a low density. The nontumor cell lines showed no inhibitory effect on exposure to a low-frequency magnetic field. The intracellular ion fluorescence (IIF) showed that the magnetic field significantly altered the membrane potential, indicating hyperpolarization of the adherent cells (ΔIIF 293 T cells: - 25%, ΔIIF Hepg2 cells: - 20% and ΔIIF A549 cells: - 13%) and depolarization of the suspended cells (ΔIIF Raji cells: + 9%). In addition, the conditioned media collected after magnetic field exposure acted on unexposed tumor cells and caused inhibition. Our findings might provide a basis for the mechanism of magnetic field interaction between cells and cell environment in the future.

Effect of 40 Hz Magnetic Field Application in Posttraumatic Muscular Atrophy Development on Muscle Mass and Contractions in Rats

Muscle atrophy refers to the deterioration of muscle tissue due to a long-term decrease in muscle function. In the present study, we simulated rectus femoris muscle atrophy experimentally and investigated the effect of pulsed electromagnetic field (PEMF) application on the atrophy development through muscle mass, maximal contraction force, and contraction-relaxation time. A quadriceps tendon rupture with a total tenotomy was created on the rats' hind limbs, inhibiting knee extension for 6 weeks, and this restriction of the movement led to the development of disuse atrophy, while the control group underwent no surgery. The operated and control groups were divided into subgroups according to PEMF application (1.5 mT for 45 days) or no PEMF. All groups were sacrificed after 6 weeks and had their entire rectus femoris removed. To measure the contraction force, the muscles were placed in an organ bath connected to a transducer. As a result of the atrophy, muscle mass and strength were reduced in the operated group, while no muscle mass loss was observed in the operated PEMF group. Furthermore, measurements of single, incomplete and full tetanic contraction force and contraction time (CT) did not change significantly in the operated group that received the PEMF application. The PEMF application prevented atrophy resulting from 6 weeks of immobility, according to the contraction parameters. The effects of PEMF on contraction force and CT provide a basis for further studies in which PEMF is investigated as a noninvasive therapy for disuse atrophy development. © 2022 Bioelectromagnetics Society.

Differential biological responses of adherent and non-adherent (cancer and non-cancerous) cells to variable extremely low frequency magnetic fields

Extremely low-frequency electromagnetic field (ELF-EMF) induces biological effects on different cells through various signaling pathways. To study the impact of the ELF-EMF on living cells under an optimal physiological condition, we have designed and constructed a novel system that eliminates several limitations of other ELF-EMF systems. Apoptosis and cell number were assessed by flow cytometry and the Trypan Blue dye exclusion method, respectively. In vitro cell survival was evaluated by colony formation assay. The distribution of cells in the cell cycle, intracellular ROS level, and autophagy were analyzed by flow cytometer. Suspended cells differentiation was assessed by phagocytosis of latex particles and NBT reduction assay. Our results showed that response to the exposure to ELF-EMF is specific and depends on the biological state of the cell. For DU145, HUVEC, and K562 cell lines the optimum results were obtained at the frequency of 0.01 Hz, while for MDA-MB-231, the optimum response was obtained at 1 Hz. Long-term exposure to ELF-EMF in adherent cells effectively inhibited proliferation by arresting the cell population at the cell cycle G2/M phase and increased intracellular ROS level, leading to morphological changes and cell death. The K562 cells exposed to the ELF-EMF differentiate via induction of autophagy and decreasing the cell number. Our novel ELF-EMF instrument could change morphological and cell behaviors, including proliferation, differentiation, and cell death.

Magnetic field effects in biology from the perspective of the radical pair mechanism

Hundreds of studies have found that weak magnetic fields can significantly influence various biological systems. However, the underlying mechanisms behind these phenomena remain elusive. Remarkably, the magnetic energies implicated in these effects are much smaller than thermal energies. Here, we review these observations, and we suggest an explanation based on the radical pair mechanism, which involves the quantum dynamics of the electron and nuclear spins of transient radical molecules. While the radical pair mechanism has been studied in detail in the context of avian magnetoreception, the studies reviewed here show that magnetosensitivity is widespread throughout biology. We review magnetic field effects on various physiological functions, discussing static, hypomagnetic and oscillating magnetic fields, as well as isotope effects. We then review the radical pair mechanism as a potential unifying model for the described magnetic field effects, and we discuss plausible candidate molecules for the radical pairs. We review recent studies proposing that the radical pair mechanism provides explanations for isotope effects in xenon anaesthesia and lithium treatment of hyperactivity, magnetic field effects on the circadian clock, and hypomagnetic field effects on neurogenesis and microtubule assembly. We conclude by discussing future lines of investigation in this exciting new area of quantum biology.

Magnetic Properties and Biocompatibility of Different Thickness (Pd/Fe)n Coatings Deposited on Pure Ti Surface via Multi Arc Ion Plating

The different thickness (Fe/Pd)_n coatings were prepared by vacuum ion plating technology on a pure Ti substrate. The (Fe/Pd)_n coatings were magnetized using an MC-4000 high-pressure magnetizing machine. Then, the effect of the (Fe/Pd)_n coating thickness on the magnetic properties was studied. The surface and section morphology, composition, phase structure, magnetic properties, and biocompatibility of the (Fe/Pd)_n coatings were studied by scanning electron microscopy, X-ray diffraction, energy-dispersive X-ray spectroscopy, and CCTC-1 digital flux field measurement. The results showed that the (Fe/Pd)_n coatings were granular, smooth, and compact, without cracks. In addition the (Fe/Pd)_n coatings formed an L₁₀ phase with a magnetic face-centered tetragonal-ordered structure after heat treatment. With the increase in the thickness of (FePd)_n coatings, the content of L₁₀ FePd phase increased and the remanence increased. The remanence values of the Fe/Pd, (Fe/Pd)₅, (Fe/Pd)₁₀, and (Fe/Pd)₁₅ magnetic coatings were 0.83 Gs, 5.52 Gs, 7.14 Gs, and 7.94 Gs, respectively. Additionally, the (Fe/Pd)_n magnetic coatings showed good blood compatibility and histocompatibility.

Histological Analysis of Bone Callus in Delayed Union Model Fracture Healing Stimulated with Pulsed Electromagnetic Fields (PEMF)

Delayed union and nonunion fractures are clinical challenges for orthopedic surgeons. The development of fracture complications, such as delayed union and nonunion fractures, is still difficult to predict. Various methods are being investigated to improve fracture healing and prevent complications in patients. There are various methods to promote fracture healing, broadly divided into biological, chemical, and physical methods. One of the most widely used physical methods to promote fracture healing is the pulsed electromagnetic field (PEMF). This study aimed to evaluate the healing process of delayed union fracture after being stimulated by PEMF. Twenty-four rats were randomly divided into two groups: the control group (n = 12) and the PEMF group (n = 12). Delayed union fracture was performed on the left femur of all rats. Subsequently, the PEMF group was given PEMF stimulus with a magnetic field intensity of 1.6 mT and a frequency of 50 Hz for 4 hours/day and 7 days/week. The fracture healing process was evaluated on days 5, 10, 18, and 28 based on the bone callus histology using safranin O fast green (SOFG) staining. The results of the histological analysis showed that bone cartilage was higher in the PEMF group than in the control group throughout the observation period. In addition, the PEMF group had less fibrous tissue at the beginning of the healing. This finding indicates PEMF stimulation has an effect on inducing osteogenesis on fracture healing and reducing the risk of delayed union.

Exposure to 60 Hz magnetic field can affect membrane proteins and membrane potential in human cancer cells

The experimental data support the hypothesis that extremely low frequency magnetic field (ELF-MF) can affect cell membranes. Since our previous studies suggested that MF changes the permeability of cell membrane, in this study we focused on the cell membrane and investigated the effect of 60 Hz, 50 mT MF on the membrane potential and membrane proteins. The membrane potentials of three cultured human cancer cell lines, A549, MES-SA, and MES-SA/Dx5, were increased by exposure to ELF-MF. When exposed to MF and an anticancer drug, changes in the membrane potentials were detected in A549 and MES-SA cells, but not in the multi drug-resistant cells, MES-SA/Dx5. We examined whether MF has an influence on the membrane proteins extracted from cultured A549 cells, using DiBAC₄(3) dye enhanced fluorescence binding to a hydrophobic site. The increase in fluorescence observed following MF exposure for 10 min indicated that the structure of the hydrophobic site on the membrane proteins changed and became more likely to bind the probe dye. A decrease in fluorescence was detected following exposure to MF for 240 min. These results indicated that 60 Hz, 50 mT MF causes changes in the membrane potential of cultured cancer cells and the conformation of membrane proteins extracted from cultured cancer cells, and has different effects depending on the exposure time.

A 50 Hz magnetic field affects hemodynamics, ECG and vascular endothelial function in healthy adults: A pilot randomized controlled trial

Application of exposure to 50/60 Hz magnetic fields (MFs) has been conducted in the treatment of muscle pain and fatigue mainly in Japan. However, whether MFs could increase blood flow leading to muscle fatigue recovery has not been sufficiently tested. We investigated the acute effects of a 50 Hz sinusoidal MF at Bmax 180 mT on hemodynamics, electrocardiogram, and vascular endothelial function in healthy young men. Three types of regional exposures to a 50 Hz MF, i.e., forearm, upper arm, or neck exposure to MF were performed. Participants who received three types of real MF exposures had significantly increased ulnar arterial blood flow velocity compared to the sham exposures. Furthermore, after muscle loading exercise, MF exposure recovered hemoglobin oxygenation index values faster and higher than sham exposure from the loading condition. Moreover, participants who received real MF exposure in the neck region had significantly increased parasympathetic high-frequency activity relative to the sham exposure. The MF exposure in the upper arm region significantly increased the brachial artery flow-mediated dilation compared to the sham exposure. Computer simulations of induced in situ electric fields indicated that the order-of-magnitude estimates of the peak values were 100-500 mV/m, depending on the exposure conditions. This study provides the first evidence that a 50 Hz MF can activate parasympathetic activity and thereby lead to increase vasodilation and blood flow via a nitric oxide-dependent mechanism. Trial registration: UMIN Clinical Trial Registry (CTR) UMIN000038834. The authors confirm that all ongoing and related trials for this drug/intervention are registered.

Pulsed high magnetic field-induced reversible blood-brain barrier permeability to enhance brain-targeted drug delivery

The present study aimed to select an effective Pulsed High Magnetic Field (PHMF) stimulation protocol that would induce the Blood-Brain Barrier's (BBB) reversible permeability to enhance brain-targeted drug delivery. PHMF was applied to the skull over the right hemisphere of 60 Wistar rats. The sham group contained other 10 rats that did not receive PHMF stimulation. The investigated parameters were repetition frequencies (0.25, 1, and 4 Hz as well as the effective low frequency combined with 10 Hz) and numbers of pulses in each train. Evans Blue Dye (EBD) uptake within the brain parenchyma was measured to select an effective PHMF stimulation protocol. BBB reversibility was evaluated by measuring EBD uptake and Gadobutrol retention, through MRI signal intensity enhancement, within brain parenchyma after exposure to the effective PHMF stimulation protocol at different time points including 0.5, 1, and 24 hours. The obtained results showed that the PHMF stimulation increased the BBB's reversible permeability; this increase was more significant for 28 pulses with 1 Hz frequency (P < .0001). Changes in EBD uptake and MRI signal intensity in the exposed side (right hemisphere) peaked within 0.5-1 hour and returned to normal levels 24 hours after exposure to the effective protocol of PHMF stimulation (28 pulses with 1 Hz frequency). The Contrast-Enhanced MRI (CE-MRI) signal intensity confirmed the changes in EBD concentration. PHMF stimulation can be used as an effective protocol for enhancing the permeability reversibly of BBB, hence considered a potential clinical approach to brain-targeted drug delivery.

Investigation into the effects of static and electric fields on bone healing process: An experimental tibial fracture model study in Wistar-Albino male rats

OBJECTIVE:

In this experimental study, we aimed to investigate whether 0 Hz-Static and 50 Hz-Electric fields have an effect on bone healing.

METHODS:

In this study, 45 male Wistar-Albino rats were equally and randomly separated into three groups as follows: a 0 Hz-Static electric field (SEF), a 50-Hz low-frequency electric field (LFEF) and a control group. A manual fracture was performed in the left tibia diaphysis of all rats, and fractures were fixed using circular plaster over the knee. The LFEF group was exposed to 50 Hz electric field for 30 minutes a day, five days a week, for a total of eight weeks. The SEF group was exposed to 0 Hz electric field within the same time interval. The control group was held in identical environmental conditions, without exposure to electric field. Periodic radiographs were taken from all the animals. At the end of this study, rats were sacrificed and mechanical/histopathologic examinations were performed.

RESULTS:

Radiologic, mechanical and histologic scores of the LFEF group were lower than those of the SEF and control groups; however, no significant difference was found in group comparisons in terms of average histologic and radiologic scores (p>0.05).

CONCLUSION:

Results extracted from the current study suggest that 0-hz static and 50-hz electric field exposures affect bone healing tissue of tibial fracture models in rats, although it is not significant.

The efficacy and safety of low-frequency rotating static magnetic field therapy combined with chemotherapy on advanced lung cancer patients: a randomized, double-blinded, controlled clinical trial

Purpose: To evaluate the efficacy and safety of magnetic field (MF) therapy by a randomized, double-blinded, controlled clinical trial.Materials and methods: From February 2016 to August 2019, patients with advanced lung cancer who conformed to inclusion criteria were enrolled in this study. Patients were assigned into MF therapy group (MF group, receiving both MF therapy and chemotherapy) and control group (CON group, receiving sham MF therapy and chemotherapy) randomly. The treatment course was 21 days and 2 hours per day. Changes of life quality assessment scales, objective response rate (ORR) and disease control rate (DCR) were analyzed as primary end points. The secondary end points were progression-free survival (PFS), change of blood cytokine concentrations and safety. This study has been registered on Clinicaltrials.gov (ID: NCT02701231).Results: 77 patients were enrolled and 60 finished the study. Comparing to CON group, more patients in MF group (66.7% vs 25.9%) were experiencing life quality improvement on day 21. Besides, MF group patients had higher concentrations of IP-10 and GM-CSF, and lower concentration of sTREM-1 in plasma. However, the two groups were having similar ORR, DCR and PFS after treatment. Moreover, MF treatment did not increase adverse events in MF group.Conclusions: MF therapy could improve life quality and modulate blood cytokine concentration in advanced lung cancer patients. Hence, it might be applied as an adjuvant therapy along with chemotherapy.

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.

The Use of Pulsed Electromagnetic Field to Modulate Inflammation and Improve Tissue Regeneration: A Review

Pulsed electromagnetic field (PEMF) is emerging as innovative treatment for regulation of inflammation, which could have significant effects on tissue regeneration. PEMF modulates inflammatory processes through the regulation of pro- and anti-inflammatory cytokine secretion during different stages of inflammatory response. Consistent outcomes in studies involving animal and human tissue have shown promise for the use of PEMF as an alternative or complementary treatment to pharmaceutical therapies. Thus, PEMF treatment could provide a novel nonpharmaceutical means of modulating inflammation in injured tissues resulting in enhanced functional recovery. This review examines the effect of PEMF on immunomodulatory cells (e.g., mesenchymal stem/stromal cells [MSCs] and macrophages [MΦ]) to better understand the potential for PEMF therapy to modulate inflammatory signaling pathways and improve tissue regeneration. This review cites published data that support the use of PEMF to improve tissue regeneration. Our studies included herein confirm anti-inflammatory effects of PEMF on MSCs and MΦ.

Rotating magnetic field delays human umbilical vein endothelial cell aging and prolongs the lifespan of Caenorhabditis elegans

The biological effects of magnetic fields are a research hotspot in the field of biomedical engineering. In this study, we further investigated the effects of a rotating magnetic field (RMF; 0.2 T, 4 Hz) on the growth of human umbilical vein endothelial cells (HUVECs) and Caenorhabditis elegans. The results showed that RMF exposure prolonged the lifespan of C. elegans and slowed the aging of HUVECs. RMF treatment of HUVECs showed that activation of adenosine 5'-monophosphate (AMP)-activated protein kinase (AMPK) was associated with decreased mitochondrial membrane potential (MMP) due to increased intracellular Ca2+ concentrations induced by endoplasmic reticulum stress in anti-aging mechanisms. RMF also promoted the health status of C. elegans by improving activity, reducing age-related pigment accumulation, delaying Aβ-induced paralysis and increasing resistance to heat and oxidative stress. The prolonged lifespan of C. elegans was associated with decreased levels of daf-16 which related to the insulin/insulin-like growth factor signaling pathway (IIS) activity and reactive oxygen species (ROS), whereas the heat shock transcription factor-1 (hsf-1) pathway was not involved. Moreover, the level of autophagy was increased after RMF treatment. These findings expand our understanding of the potential mechanisms by which RMF treatment prolongs lifespan.

The Response of Osteoblasts and Bone to Sinusoidal Electromagnetic Fields: Insights from the Literature

Electromagnetic fields (EMFs) have been proposed as a tool to ameliorate bone formation and healing. Despite their promising results, however, they have failed to enter routine clinical protocols to treat bone conditions where higher bone mass has to be achieved. This is no doubt also due to a fundamental lack of knowledge and understanding on their effects and the optimal settings for attaining the desired therapeutic effects. This review analysed the available in vitro and in vivo studies that assessed the effects of sinusoidal EMFs (SEMFs) on bone and bone cells, comparing the results and investigating possible mechanisms of action by which SEMFs interact with tissues and cells. The effects of SEMFs on bone have not been as thoroughly investigated as pulsed EMFs; however, abundant evidence shows that SEMFs affect the proliferation and differentiation of osteoblastic cells, acting on multiple cellular mechanisms. SEMFs have also proven to increase bone mass in rodents under normal conditions and in osteoporotic animals.

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.

Thermal and non-thermal health effects of low intensity non-ionizing radiation: An international perspective

Exposure to low frequency and radiofrequency electromagnetic fields at low intensities poses a significant health hazard that has not been adequately addressed by national and international organizations such as the World Health Organization. There is strong evidence that excessive exposure to mobile phone-frequencies over long periods of time increases the risk of brain cancer both in humans and animals. The mechanism(s) responsible include induction of reactive oxygen species, gene expression alteration and DNA damage through both epigenetic and genetic processes. In vivo and in vitro studies demonstrate adverse effects on male and female reproduction, almost certainly due to generation of reactive oxygen species. There is increasing evidence the exposures can result in neurobehavioral decrements and that some individuals develop a syndrome of "electro-hypersensitivity" or "microwave illness", which is one of several syndromes commonly categorized as "idiopathic environmental intolerance". While the symptoms are non-specific, new biochemical indicators and imaging techniques allow diagnosis that excludes the symptoms as being only psychosomatic. Unfortunately standards set by most national and international bodies are not protective of human health. This is a particular concern in children, given the rapid expansion of use of wireless technologies, the greater susceptibility of the developing nervous system, the hyperconductivity of their brain tissue, the greater penetration of radiofrequency radiation relative to head size and their potential for a longer lifetime exposure.

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.

Comparative Analysis of Biological Effects Induced on Different Cell Types by Magnetic Fields with Magnetic Flux Densities in the Range of 1–60 mT and Frequencies up to 50 Hz

Moderate static magnetic fields (SMFs) are generated from sources such as new-generation electric trams and trains, electric arc welding, and magnetic resonance imaging (MRI) devices, as well as during the industrial production of aluminium, while extremely low frequency pulsed magnetic fields (ELF-PMFs) are produced by house power installations, household appliances, and high voltages transmission lines. Moderate SMFs and ELF-PMFs with magnetic flux densities (B) in the range of 1–60 mT and frequencies (f) up to 50 Hz are common MF exposure sources for the population. Even though humans are continually exposed to these MFs, to date no definitive endpoint has been drawn about their safety. In this review, the state of knowledge about the biological effects induced by these MFs on different cell types will be addressed. In our own observation, the putative modulation of Ca2+/H+ and Na+/H+ plasma membrane antiporters of human peripheral blood lymphocytes (PBLs) was found to occur after a 24 h exposure to a 6 mT SMF, and the bystander effect observed on U937 cells cultivated for up to 6 h in the conditioned medium harvested from human PBLs previously exposed for 24 h to the same MF (secondary necrosis induction) will be also herein discussed.

Physical stimulations and their osteogenesis-inducing mechanisms

Physical stimulations such as magnetic, electric and mechanical stimulation could enhance cell activity and promote bone formation in bone repair process via activating signal pathways, modulating ion channels, regulating bonerelated gene expressions, etc. In this paper, bioeffects of physical stimulations on cell activity, tissue growth and bone healing were systematically summarized, which especially focused on their osteogenesis-inducing mechanisms. Detailedly, magnetic stimulation could produce Hall effect which improved the permeability of cell membrane and promoted the migration of ions, especially accelerating the extracellular calcium ions to pass through cell membrane. Electric stimulation could induce inverse piezoelectric effect which generated electric signals, accordingly up-regulating intracellular calcium levels and growth factor synthesis. And mechanical stimulation could produce mechanical signals which were converted into corresponding biochemical signals, thus activating various signaling pathways on cell membrane and inducing a series of gene expressions. Besides, bioeffects of physical stimulations combined with bone scaffolds which fabricated using 3D printing technology on bone cells were discussed. The equipments of physical stimulation system were described. The opportunities and challenges of physical stimulations were also presented from the perspective of bone repair.

The antitumor effect of static and extremely low frequency magnetic fields against nephroblastoma and neuroblastoma

Certain magnetic fields (MF) have potential therapeutic antitumor effect whereas the underlying mechanism remains undefined. In this study, a well-characterized MF was applied to two common childhood malignancies, nephroblastoma and neuroblastoma. This MF has a time-averaged total intensity of 5.1 militesla (mT), and was generated as a superimposition of a static and an extremely low frequency (ELF) MF in 50 Hertz (Hz). In nephroblastoma and neuroblastoma cell lines including G401, CHLA255, and N2a, after MF exposure of 2 h per day, the cell viability decreased significantly after 2 days. After 3 days, inhibition rates of 17-22% were achieved in these cell lines. Furthermore, the inhibition rate was positively associated with exposure time. On the other hand, when using static MF only while maintaining the same time-averaged intensity of 5.1 mT, the inhibition rate was decreased. Thus, both time and combination of ELF field were positively associated with the inhibitory effect of this MF. Exposure to the field decreased cell proliferation and induced apoptosis. Combinational use of MF together with chemotherapeutics cisplatin (DDP) was performed in both in vitro and in vivo experiments. In cell lines, combinational treatment further increased the inhibition rate compared with single use of either DDP or MF. In G401 nephroblastoma tumor model in nude mice, combination of MF and DDP resulted in significant decrease of tumor mass, and the side effect was limited in mild liver injury. MF exposure by itself did not hamper liver or kidney functions. In summary, the antitumor effect of an established MF against neuroblastoma and nephroblastoma is reported, and this field has the potential to be used in combination with DDP to achieve increased efficacy and reduce side effects in these two childhood malignancies. Bioelectromagnetics. 39:375-385, 2018. © 2018 Wiley Periodicals, Inc.

Co-Culture with Human Osteoblasts and Exposure to Extremely Low Frequency Pulsed Electromagnetic Fields Improve Osteogenic Differentiation of Human Adipose-Derived Mesenchymal Stem Cells

Human adipose-derived mesenchymal stem cells (Ad-MSCs) have been proposed as suitable option for cell-based therapies to support bone regeneration. In the bone environment, Ad-MSCs will receive stimuli from resident cells that may favor their osteogenic differentiation. There is recent evidence that this process can be further improved by extremely low frequency pulsed electromagnetic fields (ELF-PEMFs). Thus, the project aimed at (i) investigating whether co-culture conditions of human osteoblasts (OBs) and Ad-MSCs have an impact on their proliferation and osteogenic differentiation; (ii) whether this effect can be further improved by repetitive exposure to two specific ELF-PEMFs (16 and 26 Hz); (iii) and the effect of these ELF-PEMFs on human osteoclasts (OCs). Osteogenic differentiation was improved by co-culturing OBs and Ad-MSCs when compared to the individual mono-cultures. An OB to Ad-MSC ratio of 3:1 had best effects on total protein content, alkaline phosphatase (AP) activity, and matrix mineralization. Osteogenic differentiation was further improved by both ELF-PEMFs investigated. Interestingly, only repetitive exposure to 26 Hz ELF-PEMF increased Trap5B activity in OCs. Considering this result, a treatment with gradually increasing frequency might be of interest, as the lower frequency (16 Hz) could enhance bone formation, while the higher frequency (26 Hz) could enhance bone remodeling.

Repetitive low intensity magnetic field stimulation in a neuronal cell line: a metabolomics study

Low intensity repetitive magnetic stimulation of neural tissue modulates neuronal excitability and has promising therapeutic potential in the treatment of neurological disorders. However, the underpinning cellular and biochemical mechanisms remain poorly understood. This study investigates the behavioural effects of low intensity repetitive magnetic stimulation (LI-rMS) at a cellular and biochemical level. We delivered LI-rMS (10 mT) at 1 Hz and 10 Hz to B50 rat neuroblastoma cells in vitro for 10 minutes and measured levels of selected metabolites immediately after stimulation. LI-rMS at both frequencies depleted selected tricarboxylic acid (TCA) cycle metabolites without affecting the main energy supplies. Furthermore, LI-rMS effects were frequency-specific with 1 Hz stimulation having stronger effects than 10 Hz. The observed depletion of metabolites suggested that higher spontaneous activity may have led to an increase in GABA release. Although the absence of organised neural circuits and other cellular contributors (e.g., excitatory neurons and glia) in the B50 cell line limits the degree to which our results can be extrapolated to the human brain, the changes we describe provide novel insights into how LI-rMS modulates neural tissue.

Extremely low frequency pulsed electromagnetic fields cause antioxidative defense mechanisms in human osteoblasts via induction of •O2- and H2O2

Recently, we identified a specific extremely low-frequency pulsed electromagnetic field (ELF-PEMF) that supports human osteoblast (hOBs) function in an ERK1/2-dependent manner, suggesting reactive oxygen species (ROS) being key regulators in this process. Thus, this study aimed at investigating how ELF-PEMF exposure can modulate hOBs function via ROS. Our results show that single exposure to ELF-PEMF induced ROS production in hOBs, without reducing intracellular glutathione. Repetitive exposure (>3) to ELF-PEMF however reduced ROS-levels, suggesting alterations in the cells antioxidative stress response. The main ROS induced by ELF-PEMF were •O₂⁻ and H₂O₂, therefore expression/activity of antioxidative enzymes related to these ROS were further investigated. ELF-PEMF exposure induced expression of GPX3, SOD2, CAT and GSR on mRNA, protein and enzyme activity level. Scavenging •O₂⁻ and H₂O₂ diminished the ELF-PEMF effect on hOBs function (AP activity and mineralization). Challenging the hOBs with low amounts of H₂O₂ on the other hand improved hOBs function. In summary, our data show that ELF-PEMF treatment favors differentiation of hOBs by producing non-toxic amounts of ROS, which induces antioxidative defense mechanisms in these cells. Thus, ELF-PEMF treatment might represent an interesting adjunct to conventional therapy supporting bone formation under oxidative stress conditions, e.g. during fracture healing.

Effects of low-intensity pulsed electromagnetic fields on bone microarchitecture, mechanical strength and bone turnover in type 2 diabetic db/db mice

Type 2 diabetic patients have impaired bone quality, leading to increased fracture risk. Substantial evidence demonstrates that pulsed electromagnetic fields (PEMF) could resist osteopenia/osteoporosis induced by estrogen deficiency and disuse. However, the effects of PEMF on osteopenia/osteoporosis associated with diabetes, especially for more prevalent type 2 diabetes, remain poorly understood. We herein investigated the skeletal effects and mechanisms of PEMF (15 Hz, 20 Gs) on leptin receptor-deficient db/db mice with typical type 2 diabetic symptoms. Our µCT results showed that 12-week PEMF exposure significantly improved both cancellous and cortical bone microarchitecture in db/db mice. Three-point bending and biomechanical indentation testing demonstrated that PEMF improved whole-bone structural properties and tissue-level material properties in db/db mice. PEMF significantly promoted bone formation in db/db mice evidenced by increased serum osteocalcin and bone mineral apposition rate, whereas PEMF exerted no observable alteration in bone resorption. Real-time PCR showed that PEMF upregulated tibial gene expression of osteoblastogenesis-related of canonical Wnt/β-catenin signaling but not osteoclastogenesis-related RANKL-RANK signaling in db/db mice. Our findings demonstrate that PEMF improved bone quantity and quality with obvious anabolic activities in db/db mice, and imply that PEMF might become a clinically applicable treatment modality for improving bone quality in type 2 diabetic patients.

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.

Potential therapeutic mechanism of extremely low-frequency high-voltage electric fields in cells

The aim of this survey was to provide background theory based on previous research to elucidate the potential pathway by which medical devices using extremely low-frequency high-voltage electric fields (ELF-HVEF) exert therapeutic effects on the human body, and to increase understanding of the AC high-voltage electrotherapeutic apparatus for consumers and suppliers of the relevant devices. Our review revealed that an ELF field as weak as 1-10 μ V/m can induce diverse alterations of membrane proteins such as transporters and channel proteins, including changes in Ca + + binding to a specific site of the cell surface, changes in ion (e.g., Ca + + ) influx or efflux, and alterations in the ligand-receptor interaction. These alterations then induce cytoplasmic responses within cells (Ca + + , cAMP, kinases, etc.) that can have impacts on cell growth, differentiation, and other functional properties by promoting the synthesis of macromolecules. Moreover, increased cytoplasmic Ca + + involves calmodulin-dependent signaling and consequent Ca + + /calmodulin-dependent stimulation of nitric oxide synthesis. This event in turn induces the nitric oxide-cGMP-protein kinase G pathway, which may be an essential factor in the observed physiological and therapeutic responses.

Primary human osteoblasts with reduced alkaline phosphatase and matrix mineralization baseline capacity are responsive to extremely low frequency pulsed electromagnetic field exposure - Clinical implication possible

For many years electromagnetic fields (EMFs) have been used clinically with various settings as an exogenous stimulation method to promote fracture healing. However, underlying mechanisms of action and EMF parameters responsible for certain effects remain unclear. Our aim was to investigate the influence of defined EMFs on human osteoblasts' and osteoclasts' viability and function. Primary human osteoblasts and osteoclasts were treated 3 times weekly for 21 days during their maturation process using the Somagen® device (Sachtleben GmbH, Hamburg, Germany), generating defined extremely low-frequency pulsed electromagnetic fields (ELF-PEMFs). Certain ELF-PEMF treatment significantly increased the total protein content (up to 66%), mitochondrial activity (up to 91.1%) and alkaline phosphatase (AP) activity (up to 129.9%) of human osteoblasts during the entire differentiation process. Furthermore, ELF-PEMF treatment enhanced formation of mineralized matrix (up to 276%). Interestingly, ELF-PEMF dependent induction of AP activity and matrix mineralization was strongly donor dependent — only osteoblasts with a poor initial osteoblast function responded to the ELF-PEMF treatment. As a possible regulatory mechanism, activation of the ERK1/2 signaling pathway was identified. Maturation of osteoclasts from human monocytes was not affected by the ELF-PEMF treatment. In summary the results indicate that a specific ELF-PEMF treatment with the Somagen® device improves viability and maturation of osteoblasts, while osteoclast viability and maturation was not affected. Hence, ELF-PEMF might represent an interesting adjunct to conventional therapy supporting bone formation during fracture healing or even for the treatment of osteoporosis.

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Exposure to extremely low-frequency pulsed electromagnetic fields (ELF-PEMFs) increases viability of human osteoblasts.

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Exposure to specific ELF-PEMFs improves primary human osteoblasts’ function.

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Especially osteoblasts with a low differentiation capacity profit from the ELF-PEMF exposure.

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For the observed effects ERK1/2 activation is pivotal.

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Osteoclast viability and function is not affected by the same ELF-PEMF.

Pulsed electromagnetic fields promote osteoblast mineralization and maturation needing the existence of primary cilia

Although pulsed electromagnetic fields (PEMFs) have been approved as a therapy for osteoporosis, action mechanisms and optimal parameters are elusive. To determine the optimal intensity, exposure effects of 50 Hz PEMFs of 0.6-3.6 mT (0.6 interval at 90 min/day) were investigated on proliferation and osteogenic differentiation of cultured calvarial osteoblasts. All intensity groups stimulated proliferation significantly with the highest effect at 0.6 mT. The 0.6 mT group also obtained the optimal osteogenic effect as demonstrated by the highest ALP activity, ALP(+) CFU-f colony formation, nodule mineralization, and expression of COL-1 and BMP-2. To verify our hypothesis that the primary cilia are the cellular sensors for PEMFs, osteoblasts were also transfected with IFT88 siRNA or scrambled control, and osteogenesis-promoting effects of 0.6 mT PEMFs were found abrogated when primary cilia were inhibited by IFT88 siRNA. Thus primary cilia of osteoblasts play an indispensable role in mediating PEMF osteogenic effect in vitro.

Exposure to extremely low frequency electromagnetic fields alters the calcium dynamics of cultured entorhinal cortex neurons

Previous studies have revealed that extremely low frequency electromagnetic field (ELF-EMF) exposure affects neuronal dendritic spine density and NMDAR and AMPAR subunit expressions in the entorhinal cortex (EC). Although calcium signaling has a critical role in control of EC neuronal functions, however, it is still unclear whether the ELF-EMF exposure affects the EC neuronal calcium homeostasis. In the present study, using whole-cell recording and calcium imaging, we record the whole-cell inward currents that contain the voltage-gated calcium currents and show that ELF-EMF (50Hz, 1mT or 3mT, lasting 24h) exposure does not influence these currents. Next, we specifically isolate the high-voltage activated (HVA) and low-voltage activated (LVA) calcium channels-induced currents. Similarly, the activation and inactivation characteristics of these membrane calcium channels are also not influenced by ELF-EMF. Importantly, ELF-EMF exposure reduces the maximum amplitude of the high-K(+)-evoked calcium elevation in EC neurons, which is abolished by thapsigargin, a Ca(2+) ATPase inhibitor, to empty the intracellular calcium stores of EC neurons. Together, these findings indicate that ELF-EMF exposure specifically influences the intracellular calcium dynamics of cultural EC neurons via a calcium channel-independent mechanism.

Pulsed electromagnetic field enhances brain-derived neurotrophic factor expression through L-type voltage-gated calcium channel- and Erk-dependent signaling pathways in neonatal rat dorsal root ganglion neurons

Although pulsed electromagnetic field (PEMF) exposure has been reported to promote neuronal differentiation, the mechanism is still unclear. Here, we aimed to examine the effects of PEMF exposure on brain-derived neurotrophic factor (Bdnf) mRNA expression and the correlation between the intracellular free calcium concentration ([Ca(2+)]i) and Bdnf mRNA expression in cultured dorsal root ganglion neurons (DRGNs). Exposure to 50Hz and 1mT PEMF for 2h increased the level of [Ca(2+)]i and Bdnf mRNA expression, which was found to be mediated by increased [Ca(2+)]i from Ca(2+) influx through L-type voltage-gated calcium channels (VGCCs). However, calcium mobilization was not involved in the increased [Ca(2+)]i and BDNF expression, indicating that calcium influx was one of the key factors responding to PEMF exposure. Moreover, PD098059, an extracellular signal-regulated kinase (Erk) inhibitor, strongly inhibited PEMF-dependant Erk1/2 activation and BDNF expression, indicating that Erk activation is required for PEMF-induced upregulation of BDNF expression. These findings indicated that PEMF exposure increased BDNF expression in DRGNs by activating Ca(2+)- and Erk-dependent signaling pathways.

The relationship between adolescents' well-being and their wireless phone use: a cross-sectional study

BACKGROUND

The exposure of young people to radiofrequency electromagnetic fields (RF-EMFs) has increased rapidly in recent years with their increased use of cellphones and use of cordless phones and WiFi. We sought to ascertain associations between New Zealand early-adolescents' subjective well-being and self-reported use of, or exposure to, wireless telephone and internet technology.

METHODS

In this cross-sectional survey, participants completed questionnaires in class about their cellphone and cordless phone use, their self-reported well-being, and possible confounding information such as whether they had had influenza recently or had a television in the bedroom. Parental questionnaires provided data on whether they had WiFi at home and cordless phone ownership and model. Data were analysed with Ordinal Logistic Regression adjusting for common confounders. Odds ratios (OR) and 95% confidence intervals were calculated.

RESULTS

The number and duration of cellphone and cordless phone calls were associated with increased risk of headaches (>6 cellphone calls over 10 minutes weekly, adjusted OR 2.4, CI 1.2-4.8; >15 minutes cordless use daily adjusted OR 1.74, CI 1.1-2.9)). Texting and extended use of wireless phones was related to having a painful 'texting' thumb). Using a wired cellphone headset was associated with tinnitus (adjusted OR 1.8, CI 1.0-3.3), while wireless headsets were associated with headache (adjusted OR 2.2, CI 1.1-4.5), feeling down/depressed (adjusted OR 2.0, CI 1.1-3.8), and waking in the night (adjusted OR 2.4, CI 1.2-4.8). Several cordless phone frequencies bands were related to tinnitus, feeling down/depressed and sleepiness at school, while the last of these was also related to modulation. Waking nightly was less likely for those with WiFi at home (adjusted OR 0.7, CI 0.4-0.99). Being woken at night by a cellphone was strongly related to tiredness at school (OR 3.49, CI 1.97-6.2).

CONCLUSIONS

There were more statistically significant associations (36%) than could be expected by chance (5%). Several were dose-dependent relationships. To safeguard young people's well-being, we suggest limiting their use of cellphones and cordless phones to less than 15 minutes daily, and employing a speaker-phone device for longer daily use. We recommend parental measures are taken to prevent young people being woken by their cellphones.

Antagonistic effects of a 50 Hz magnetic field and melatonin in the proliferation and differentiation of hepatocarcinoma cells

BACKGROUND/AIMS

Epidemiological and experimental evidence exists indicating that exposure to weak, extremely low frequency magnetic fields (ELF - MF) could affect cancer progression. It has been proposed that such hypothetical action could be mediated by MF-induced effects on the cellular response to melatonin (MEL), a potentially oncostatic neurohormone. The present study investigates the response of HepG2 cells to intermittent exposure to a 50 Hz, 10 µT MF, in the presence or absence of MEL at physiological (10 nM) or pharmacological doses (1 µM).

METHODS

The Trypan blue cell exclusion test, BrdU incorporation and PCNA expression assays were carried out to assess the cellular response in terms of viability and proliferation. In addition, albumin and alpha-fetoprotein, were analyzed as specific hepatocellular differentiation markers.

RESULTS

The results indicate that the MF exerts significant cytoproliferative and dedifferentiating effects that can be prevented by 10 nM MEL. Conversely, MEL exerts cytostatic and differentiating effects on HepG2 that are abolished by simultaneous exposure to MF.

CONCLUSION

As a whole, these results support the hypothesis that ELF - MF and MEL exert opposite, mutually counteracting effects on cell proliferation and differentiation.