Protective effect of low frequency low energy pulsing electromagnetic fields on acute experimental myocardial infarcts in rats

Electromagnetic field and cardiovascular diseases: A state-of-the-art review of diagnostic, therapeutic, and predictive values

Despite encouraging advances in early diagnosis and treatment, cardiovascular diseases (CVDs) remained a leading cause of morbidity and mortality worldwide. Increasing evidence has shown that the electromagnetic field (EMF) influences many biological processes, which has attracted much attention for its potential therapeutic and diagnostic modalities in multiple diseases, such as musculoskeletal disorders and neurodegenerative diseases. Nonionizing EMF has been studied as a therapeutic or diagnostic tool in CVDs. In this review, we summarize the current literature ranging from in vitro to clinical studies focusing on the therapeutic potential (external EMF) and diagnostic potential (internal EMF generated from the heart) of EMF in CVDs. First, we provided an overview of the therapeutic potential of EMF and associated mechanisms in the context of CVDs, including cardiac arrhythmia, myocardial ischemia, atherosclerosis, and hypertension. Furthermore, we investigated the diagnostic and predictive value of magnetocardiography in CVDs. Finally, we discussed the critical steps necessary to translate this promising approach into clinical practice.

Acute and Chronic Exposure to 900 MHz Radio Frequency Radiation Activates p38/JNK-mediated MAPK Pathway in Rat Testis

The use of electronic devices such as mobile phones has had a long stretch of rapid growth all over the world. Therefore, exposure to radio frequency radiation (RFR) has increased enormously. Here, we aimed to assess the balance between cell death and proliferation and also investigate the involvement of the JNK/p38 MAPK signaling pathway in the testis of rats exposed to 900 MHz RFR in acute and chronic periods (2 h/day, 5 days/week) for 1 or 10 weeks, respectively. The expression of proliferating cell nuclear antigen (PCNA), Bcl-xL, cleaved caspase-3, phosphorylated-JNK (p-JNK), and phosphorylated-p38 (p-p38) was analyzed in line with histopathology and TUNEL analysis in rat testis. There were no histopathological differences between sham and RFR groups in the acute and chronic groups. PCNA expression was not altered between groups in both periods. However, alterations for cleaved caspase-3 and Bcl-xL were observed depending on the exposure period. TUNEL analysis showed a significant increase in the RFR group in the acute period, whereas no difference in the chronic groups for the apoptotic index was reported. In addition, both p-p38 and p-JNK protein expressions increased significantly in RFR groups in both periods. Our study indicated that 900 MHz RFR might result in alterations during acute period exposure for several parameters, but this can be ameliorated in the chronic period in rat testis. Here, we also report the involvement of the p38/JNK-mediated MAPK pathway after exposure to 900 MHz RFR. Hence, this information might shed light in future studies toward detailed molecular mechanisms in male reproduction and infertility.

Pulsed Electromagnetic Fields: A Novel Attractive Therapeutic Opportunity for Neuroprotection After Acute Cerebral Ischemia

OBJECTIVES

Acute cerebral ischemia is characterized by several pathological processes evolving during time, which contribute to the final tissue damage. Secondary processes, such as prolonged inflammatory response, impaired mitochondrial function and oxidative stress, are responsible for the progression of brain injury to the peri-infarct area, called "penumbra." Adenosine has been shown to play a crucial role in regulating the inflammatory cascade following brain ischemia. Pulsed electromagnetic fields (PEMFs) act as modulators of adenosine receptors, increasing the functionality of the endogenous adenosine. In particular, PEMF exposure induces a significant upregulation of A_2A and A₃ adenosine receptors in different neuronal cell types. Several lines of evidence suggest that PEMF exposure might play a neuroprotective role after ischemic damage.

MATERIALS AND METHODS

This review summarizes the current knowledge on the mechanism of action of PEMFs and their biological effects on neuronal damage both in preclinical and clinical studies.

RESULTS

PEMFs counteract hypoxia-induced apoptosis and ROS production in neuronal-like cells and exert a strong anti-inflammatory effect on microglial cells. Data from stroke animal models showed that PEMFs exposure is able to reduce the size of the infarct area and decrease the levels of pro-inflammatory mediators. In clinical studies, PEMFs stimulation proved to be safe and well tolerated. Preliminary results on acute ischemic stroke patients showed a dose-dependent reduction in the lesion size.

CONCLUSIONS

Altogether, these data demonstrate the efficacy of PEMFs against several mechanisms underlying ischemic damage and suggest that PEMFs might represent a novel noninvasive adjunctive treatment for acute ischemic stroke, providing neuroprotection and reducing functional deficits following ischemia.

The Effect of Pulsed Electromagnetic Fields on Angiogenesis

A pulsed electromagnetic field (PEMF) has been used to treat inflammation-based diseases such as osteoporosis, neurological injury, and osteoarthritis. Numerous animal experiments and in vitro studies have shown that PEMF may affect angiogenesis. For ischemic diseases, in theory, blood flow may be richer by increasing the number of blood vessels which supply blood to ischemic tissue. PEMF plays a role in enhancing angiogenesis, and their clinical application may go far beyond the current scope. In this review, we analyzed and summarized the effects and possible mechanisms of PEMF on angiogenesis. Most studies have shown that PEMF with specific parameters can promote angiogenesis, which is manifested by an increased vascular growth rate and increased capillary density. The potential mechanisms consist of promoting vascular endothelial cell proliferation, migration, and tube formation, and increasing the expression level of vascular endothelial growth factor (VEGF), fibroblast growth factor 2 (FGF2), angiopoietin-2 (Ang-2), and other angiogenic growth factors. Additionally, PEMF has an impact on the activation of voltage-gated calcium channels (VGCC). Bioelectromagnetics. © 2021 Bioelectromagnetics Society.

A combined low-frequency electromagnetic and fluidic stimulation for a controlled drug release from superparamagnetic calcium phosphate nanoparticles: potential application for cardiovascular diseases

Alternative drug delivery approaches to treat cardiovascular diseases are currently under intense investigation. In this domain, the possibility to target the heart and tailor the amount of drug dose by using a combination of magnetic nanoparticles (NPs) and electromagnetic devices is a fascinating approach. Here, an electromagnetic device based on Helmholtz coils was generated for the application of low-frequency magnetic stimulations to manage drug release from biocompatible superparamagnetic Fe-hydroxyapatite NPs (FeHAs). Integrated with a fluidic circuit mimicking the flow of the cardiovascular environment, the device was efficient to trigger the release of a model drug (ibuprofen) from FeHAs as a function of the applied frequencies. Furthermore, the biological effects on the cardiac system of the identified electromagnetic exposure were assessed in vitro and in vivo by acute stimulation of isolated adult cardiomyocytes and in an animal model. The cardio-compatibility of FeHAs was also assessed in vitro and in an animal model. No alterations of cardiac electrophysiological properties were observed in both cases, providing the evidence that the combination of low-frequency magnetic stimulations and FeHAs might represent a promising strategy for controlled drug delivery to the failing heart.

Adenosine Receptors as a Biological Pathway for the Anti-Inflammatory and Beneficial Effects of Low Frequency Low Energy Pulsed Electromagnetic Fields

Several studies explored the biological effects of low frequency low energy pulsed electromagnetic fields (PEMFs) on human body reporting different functional changes. Much research activity has focused on the mechanisms of interaction between PEMFs and membrane receptors such as the involvement of adenosine receptors (ARs). In particular, PEMF exposure mediates a significant upregulation of A_2A and A₃ARs expressed in various cells or tissues involving a reduction in most of the proinflammatory cytokines. Of particular interest is the observation that PEMFs, acting as modulators of adenosine, are able to increase the functionality of the endogenous agonist. By reviewing the scientific literature on joint cells, a double role for PEMFs could be hypothesized in vitro by stimulating cell proliferation, colonization of the scaffold, and production of tissue matrix. Another effect could be obtained in vivo after surgical implantation of the construct by favoring the anabolic activities of the implanted cells and surrounding tissues and protecting the construct from the catabolic effects of the inflammatory status. Moreover, a protective involvement of PEMFs on hypoxia damage in neuron-like cells and an anti-inflammatory effect in microglial cells have suggested the hypothesis of a positive impact of this noninvasive biophysical stimulus.

Low Frequency Electromagnetic Field Conditioning Protects against I/R Injury and Contractile Dysfunction in the Isolated Rat Heart

Low frequency electromagnetic field (LF-EMF) decreases the formation of reactive oxygen species, which are key mediators of ischemia/reperfusion (I/R) injury. Therefore, we hypothesized that the LF-EMF protects contractility of hearts subjected to I/R injury. Isolated rat hearts were subjected to 20 min of global no-flow ischemia, followed by 30 min reperfusion, in the presence or absence of LF-EMF. Coronary flow, heart rate, left ventricular developed pressure (LVDP), and rate pressure product (RPP) were determined for evaluation of heart mechanical function. The activity of cardiac matrix metalloproteinase-2 (MMP-2) and the contents of coronary effluent troponin I (TnI) and interleukin-6 (IL-6) were measured as markers of heart injury. LF-EMF prevented decreased RPP in I/R hearts, while having no effect on coronary flow. In addition, hearts subjected to I/R exhibited significantly increased LVDP when subjected to LF-EMF. Although TnI and IL-6 levels were increased in I/R hearts, their levels returned to baseline aerobic levels in I/R hearts subjected to LF-EMF. The reduced activity of MMP-2 in I/R hearts was reversed in hearts subjected to LF-EMF. The data presented here indicate that acute exposure to LF-EMF protects mechanical function of I/R hearts and reduces I/R injury.

Protective effects of low-frequency magnetic fields on cardiomyocytes from ischemia reperfusion injury via ROS and NO/ONOO-

Background. Cardiac ischemia reperfusion (I/R) injury is associated with overproduction of reactive oxygen species (ROS). Low frequency pulse magnetic fields (LFMFs) have been reported to decrease ROS generation in endothelial cells. Whether LFMFs could assert protective effects on myocardial from I/R injury via ROS regulation remains unclear. Methods. To simulate in vivo cardiac I/R injury, neonatal rat cardiomyocytes were subjected to hypoxia reoxygenation (H/R) with or without exposure to LFMFs. Cell viability, apoptosis index, ROS generation (including O₂⁻ and ONOO⁻), and NO production were measured in control, H/R, and H/R + LFMF groups, respectively. Results. H/R injury resulted in cardiomyocytes apoptosis and decreased cell viability, whereas exposure to LFMFs before or after H/R injury significantly inhibited apoptosis and improved cell viability (P < 0.05). LFMFs treatment could suppress ROS (including O₂⁻ and ONOO⁻) generation induced by H/R injury, combined with decreased NADPH oxidase activity. In addition, LFMFs elevated NO production and enhanced NO/ONOO⁻ balance in cardiomyocytes, and this protective effect was via the phosphorylation of endothelial nitric oxide synthase (eNOS). Conclusion. LFMFs could protect myocardium against I/R injury via regulating ROS generation and NO/ONOO⁻ balance. LFMFs treatment might serve as a promising strategy for cardiac I/R injury.

Extremely low frequency electromagnetic fields activate the ERK cascade, increase hsp70 protein levels and promote regeneration in Planaria

PURPOSE

To use regenerating Planaria Dugesia dorotocethala as a model to determine whether an intermittent modulated extremely low frequency electro-magnetic field (ELF-EMF) produces elevated levels of the heat shock protein hsp70 and stimulates intracellular pathways known to be involved in injury and repair. We focused on serum response element (SRE) binding through the extra-cellular signal-regulated kinase (ERK) cascade.

MATERIALS AND METHODS

Planaria were transected equidistant between the tip of the head and the tip of the tail. Individual head and tail portions from the same worm were exposed to a 60 Hertz 80 milliGauss ELF-EMF for 1 h twice daily for 15 days post-transection under carefully controlled exposure conditions. The regenerating heads and tails were photographed and the lengths measured at three-day intervals. In other experiments, the timing of the appearance of pigmented eyes was monitored in the tail portion at 12-h intervals following transection in both ELF-EMF exposed and sham control. In some experiments protein lysates were analysed for hsp70 levels, doubly phosphorylated (pp)-ERK, Elk-1 kinase activity and serum response factor (SRF)-SRE binding.

RESULTS

ELF-EMF exposure during the initial 3-days post-surgery caused a significant increase in regeneration for both heads and tails, but especially tails. The first appearance of eyes occurred at day seven post-transection in tail portions exposed to ELF-EMF. In the sham control tail samples the initial appearance of eyes occurred 48 h later. Concurrently, ELF-EMF-exposed heads and tails exhibited an elevation in the level of hsp70 protein, an activation of an ERK cascade, and an increase in SRF-SRE binding.

CONCLUSION

Exposures to a modulated sinusoidal ELF-EMF were delivered by a Helmholtz configuration at a frequency of 60 Hz and 80 mG twice a day for one hour. This is accompanied by an increase in hsp70 protein levels, activation of specific kinases and upregulation of transcription factors that are generally associated with repair processes.

Differentiation of human adult cardiac stem cells exposed to extremely low-frequency electromagnetic fields

AIMS

Modulation of cardiac stem cell (CSC) differentiation with minimal manipulation is one of the main goals of clinical applicability of cell therapy for heart failure. CSCs, obtained from human myocardial bioptic specimens and grown as cardiospheres (CSps) and cardiosphere-derived cells (CDCs), can engraft and partially regenerate the infarcted myocardium, as previously described. In this paper we assessed the hypothesis that exposure of CSps and CDCs to extremely low-frequency electromagnetic fields (ELF-EMFs), tuned at Ca2+ ion cyclotron energy resonance (Ca2+-ICR), may drive their differentiation towards a cardiac-specific phenotype.

METHODS AND RESULTS

A significant increase in the expression of cardiac markers was observed after 5 days of exposure to Ca2+-ICR in both human CSps and CDCs, as evidenced at transcriptional, translational, and phenotypical levels. Ca2+ mobilization among intracellular storages was observed and confirmed by compartmentalized analysis of Ca2+ fluorescent probes.

CONCLUSIONS

These results suggest that ELF-EMFs tuned at Ca2+-ICR could be used to drive cardiac-specific differentiation in adult cardiac progenitor cells without any pharmacological or genetic manipulation of the cells that will be used for therapeutic purposes.

Electromagnetic field therapy delays cellular senescence and death by enhancement of the heat shock response

Hormesis may result when mild repetitive stress increases cellular defense against diverse injuries. This process may also extend in vitro cellular proliferative life span as well as delay and reverse some of the age-dependent changes in both replicative and non-replicative cells. This study evaluated the potential hormetic effect of non-thermal repetitive electromagnetic field shock (REMFS) and its impact on cellular aging and mortality in primary human T lymphocytes and fibroblast cell lines. Unlike previous reports employing electromagnetic radiation, this study used a long wave length, low energy, and non-thermal REMFS (50MHz/0.5W) for various therapeutic regimens. The primary outcomes examined were age-dependent morphological changes in cells over time, cellular death prevention, and stimulation of the heat shock response. REMFS achieved several biological effects that modified the aging process. REMFS extended the total number of population doublings of mouse fibroblasts and contributed to youthful morphology of cells near their replicative lifespan. REMFS also enhanced cellular defenses of human T cells as reflected in lower cell mortality when compared to non-treated T cells. To determine the mechanism of REMFS-induced effects, analysis of the cellular heat shock response revealed Hsp90 release from the heat shock transcription factor (HSF1). Furthermore, REMFS increased HSF1 phosphorylation, enhanced HSF1-DNA binding, and improved Hsp70 expression relative to non-REMFS-treated cells. These results show that non-thermal REMFS activates an anti-aging hormetic effect as well as reduces cell mortality during lethal stress. Because the REMFS configuration employed in this study can potentially be applied to whole body therapy, prospects for translating these data into clinical interventions for Alzheimer's disease and other degenerative conditions with aging are discussed.

The influence of extremely low frequency magnetic fields on cytoprotection and repair

Ischemia-reperfusion injuries, such as those suffered from various types of cardiovascular disease, are major causes of death and disability. For relatively short periods of ischemia, much of the damage is potentially reversible and in fact, does not occur until the influx of oxygen during the reperfusion stage. Because of this, there is a window of opportunity to protect the ischemic tissue. Here, we review several mechanisms of protection, such as heat shock proteins, opioids, collateral blood flow, and nitric oxide induction, and the evidence indicating that magnetic fields may be used as a means of providing protection via each of these mechanisms. While there are few studies demonstrating direct protection with magnetic field therapies, there are a number of published reports indicating that electromagnetic fields may be able to influence some of the biochemical systems with protective applications.

Skeletal muscle HSP72 and norepinephrine response to static magnetic field in rat

The present work was undertaken in order to investigate the noradrenergic system and skeletal muscle heat shock protein 72 (HSP72) response to static magnetic field (MF) in male rats. At thermoneutrality (25 degrees C), the exposition of rats 1 hour/day for 5 consecutive days to MF of 128 mT (m tesla) induced an increase in norepinephrine content in gastrocnemius muscle (+25%, p < 0.05) but had no effect at 67 mT (+1%, p > 0.05), indicating a stimulatory effect of sub-acute MF exposure on the noradrenergic system activity. Moreover, exposed rats to MF displayed a non-significant increase of HSP72 levels in gastrocnemius muscles (+29%, p > 0.05). The results indicate that noradrenergic systems in rat's gastrocnemius muscles are affected by MF exposure. Interestingly, sub-acute exposure insufficiency increased HSP72 levels in gastrocnemius muscles.

Microcirculatory effects of pulsed electromagnetic fields

PURPOSE

Pulsed electromagnetic fields (PEMF) are used clinically to expedite healing of fracture non-unions, however, the mechanism of action by which PEMF stimulation is effective is unknown. The current study examined the acute effects of PEMF stimulation on arteriolar microvessel diameters in the rat cremaster muscle. The study hypothesis was that PEMF would increase arteriolar diameters, a potential mechanism involved in the healing process.

METHODS

Local PEMF stimulation/sham stimulation of 2 or 60 min duration was delivered to the cremaster muscle of anesthetized rats. Arteriolar diameters were measured before and after stimulation/sham stimulation using intravital microscopy. Systemic hemodynamics also were monitored during PEMF stimulation.

RESULTS

Local PEMF stimulation produced significant (p<0.001) vasodilation, compared to pre-stimulation values, in cremasteric arterioles in anesthetized rats (n=24). This dilation occurred after 2 min of stimulation (9% diameter increase) and after 1 h of stimulation (8.7% diameter increase). Rats receiving "sham" stimulation (n=15) demonstrated no statistically significant change in arteriolar diameter following either "sham" stimulation period. PEMF stimulation of the cremaster (n=4 rats) did not affect systemic arterial pressure or heart rate, nor was it associated with a change in tissue environmental temperature.

CONCLUSIONS

These results support the hypothesis that local application of a specific PEMF waveform can elicit significant arteriolar vasodilation. Systemic hemodynamics and environmental temperature could not account for the observed microvascular responses.

18F-labelled annexin V: a PET tracer for apoptosis imaging

Annexin V can be used to detect apoptotic cells in vitro and in vivo, based on its ability to identify extracellular phosphatidylserine, which arises during apoptosis. In the present study, we examined the synthesis of fluorine-18 labelled annexin V as a positron emission tomography tracer for apoptosis imaging. The distribution of [18F]annexin V and technetium-99m labelled annexin V, a well-characterised SPET tracer for apoptosis imaging, was compared. [18F]annexin V was synthesised using N-succinimidyl 4-[18F]fluorobenzoate as an 18F labelling reagent. Synthesised and purified [18F]annexin V was confirmed by SDS-PAGE. In an ex vivo imaging experiment, [18F]annexin V was intravenously injected into rats 24 h after the induction of myocardial ischaemia, and accumulation in the left ventricle was examined. [18F]annexin V accumulated in the infarct area of the left ventricle, where apoptotic cells were observed. In separate experiments, [18F]annexin V or [(99m)Tc]annexin V was intravenously injected into ischaemic or normal animals, and the distribution of the tracers was compared. In ischaemic animals, accumulation of [18F]annexin V and [(99m)Tc]annexin V in the infarct area was about threefold higher than in the non-infarct area. Furthermore, the ratio of accumulation in the normal heart to the blood radioactivity was not significantly different between the tracers. In normal animals, however, the uptake of [18F]annexin V in the liver, spleen and kidney was much lower than that of [(99m)Tc]annexin V. The low uptake of [18F]annexin V in these organs might represent an advantage over [(99m)Tc]annexin V.

Microwave exposure induces Hsp70 and confers protection against hypoxia in chick embryos

To determine if microwave exposure could elicit a biological effect in the absence of thermal stress, studies were designed in which chick embryos were exposed to athermal microwave radiation (915 MHz) to look for induction of Hsp70, a protein produced during times of cellular stress that aids in the protection of cellular components. Levels of Hsp70 were found to increase within 2 h, with maximum expression ( approximately 30% higher than controls) typically occurring by 3 h from the start of exposure. Other embryos were exposed to microwave radiation prior to being subjected to hypoxic stress, and were found to have significantly higher survival (P < 0.05) following re-oxygenation than non-exposed controls. The results of these studies indicate that not only can athermal microwave exposures activate the stress protein response pathway; they can also enhance survivability following exposure to a subsequent, potentially lethal stress. From a public health standpoint, it is important that more studies be performed to determine if repeated exposures, a condition likely to be found in cell phone use, are still beneficial.

Can the Q Link Ally, a form of Sympathetic Resonance Technology (SRT), attenuate acute mobile phone-related changes to neural function?

OBJECTIVES

Exposure to active mobile phones (MP) has been shown to affect human neural function as shown by the electroencephalogram (EEG). Although it has not been determined whether such effects are harmful, a number of devices have been developed that attempt to minimize these MP-related effects. One such device, the Q Link Ally (QL; Clarus Products, International, L.L.C., San Rafael, CA), is argued to affect the human organism in such a way as to attenuate the effect of MPs. The present pilot study was designed to determine whether there is any indication that QL does alter MP-related effects on the human EEG.

DESIGN

Twenty-four (24) subjects participated in a single-blind, fully counterbalanced crossover design in which subjects' resting EEG and phase-locked neural responses to auditory stimuli were assessed under conditions of either active MP or active MP plus QL.

RESULTS

The addition of QL to the MP condition increased resting EEG in the gamma range and did so as a function of exposure duration, and it attenuated MP-related effects in the delta and alpha range (at trend-level). The addition of the QL also affected phase-locked neural responses, with a laterality reversal in the alpha range and an alteration to changes over time in the delta range, a reduction of the MP-related beta decrease over time at fronto-posterior sites, and a global reduction in the gamma range that increased as a function of exposure duration. No unambiguous relations were found between these changes and either performance or psychologic state.

CONCLUSIONS

This pilot study suggests that the addition of the QL to active MP-exposure does affect neural function in humans, altering both resting EEG patterns and the evoked neural response to auditory stimuli, and that there is a tendency for some MP-related changes to the EEG to be attenuated by the QL.