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

Technical Report: Efficacy and Safety of Low-Intensity Transcranial Magnetic Stimulation in the Remission of Depressive Symptoms in Patients With Treatment-Resistant Depression in Mexico

Transcranial magnetic stimulation (TMS) is a non-invasive neuromodulation technique that induces action potentials in the stimulated cortical area and has been approved by the Food and Drug Administration (FDA) for the treatment of major depressive disorder (MDD). The prevalence of MDD in Mexico almost tripled after the COVID-19 pandemic. In this study, we evaluated the safety and therapeutic effects of low-intensity TMS (Li-TMS) - characterized by inducing electric currents below the action potential threshold on the cerebral cortex - in 41 subjects diagnosed with treatment-resistant depression (TRD). A Li-TMS device dispensed repetitive magnetic pulses at 30 mT for 60 minutes during 20 sessions (once daily from Monday to Saturday) with the theta burst pattern. Our results suggest that Li-TMS is a safe therapy with antidepressant effects, demonstrated by the decrease in Beck Depression Inventory (BDI) scores and lessening of depressive symptoms.

Electromagnetic fields regulate calcium-mediated cell fate of stem cells: osteogenesis, chondrogenesis and apoptosis

Electromagnetic fields (EMF) are increasing in popularity as a safe and non-invasive therapy. On the one hand, it is widely acknowledged that EMF can regulate the proliferation and differentiation of stem cells, promoting the undifferentiated cells capable of osteogenesis, angiogenesis, and chondroblast differentiation to achieve bone repair purpose. On the other hand, EMF can inhibit tumor stem cells proliferation and promote apoptosis to suppress tumor growth. As an essential second messenger, intracellular calcium plays a role in regulating cell cycle, such as proliferation, differentiation and apoptosis. There is increasing evidence that the modulation of intracellular calcium ion by EMF leads to differential outcomes in different stem cells. This review summarizes the regulation of channels, transporters, and ion pumps by EMF-induced calcium oscillations. It furtherly discusses the role of molecules and pathways activated by EMF-dependent calcium oscillations in promoting bone and cartilage repair and inhibiting tumor stem cells growth.

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.

EMF promote BMSCs differentiation and functional recovery in hemiparkinsonian rats

Bone marrow mesenchymal stem cells (BMSCs) have self-renewal ability while maintaining the proliferation facility. The BMSCs reproducing ability could affect by electromagnetic fields (EMFs) as a physical inducing factor. We focused on the EMF (400 µT, 75 Hz) exposed multi-potential BMSCs which differentiated and successfully implanted in the substantia nigra pars compacta (SNpc) of Parkinson's disease rat model. The purified BMSCs are exposed to sinusoidal and square waveform EMF (1h/1 week or 7h/1 day) then injected into the left SNpc of Parkinson's rats. To evaluate the morphology of EMF exposed BMSCs, the cresyl violet staining labeled the Nissl bodies. After evaluation of the rat's activity by behavioral tests (open-field and rotarod tests), the brains were obtained for the preparation of SNpc blocks and carry out the cresyl violet staining. Cell morphology proved most cell differentiation to neurons in the sinusoidal EMF groups. In the sinusoidal EMF exposure groups, large and small neurons were seen with apparent synapses. Although in the square EMF exposed groups some neurons were seen, most of the differentiated cells were astrocytes, microglia, and oligodendrocyte. The results confirmed an improvement in locomotors' activity of BMSC alone and sinusoidal EMF exposed groups. We presented a low-frequency EMF (75 Hz) to promote the capability of BMSC proliferation, differentiation to neurons and glial cells, and motor coordination activity in the treatment of hemiparkinsonian rats.

Thapsigargin blocks electromagnetic field-elicited intracellular Ca2+ increase in HEK 293 cells

Biological effects of electromagnetic fields (EMFs) have previously been identified for cellular proliferation and changes in expression and conduction of diverse types of ion channels. The major effect elicited by EMFs seems to be directed toward Ca²⁺ homeostasis. This is particularly remarkable since Ca²⁺ acts as a central modulator in various signaling pathways, including, but not limited to, cell differentiation and survival. Despite this, the mechanisms underlying this modulation have yet to be unraveled. Here, we assessed the effect of EMFs on intracellular [Ca²⁺], by exposing HEK 293 cells to both radio‐frequency electromagnetic fields (RF‐EMFs) and static magnetic fields (SMFs). We detected a constant and significant increase in [Ca²⁺] subsequent to exposure to both types of fields. Strikingly, the increase was nulled by administration of 10 μM Thapsigargin, a blocker of sarco/endoplasmic reticulum Ca²⁺‐ATPases (SERCAs), indicating the involvement of the endoplasmic reticulum (ER) in EMF‐related modulation of Ca²⁺ homeostasis.

A little goes a long way: Neurobiological effects of low intensity rTMS and implications for mechanisms of rTMS

Repetitive transcranial magnetic stimulation (rTMS) is a widespread technique in neuroscience and medicine, however its mechanisms are not well known. In this review, we consider intensity as a key therapeutic parameter of rTMS, and review the studies that have examined the biological effects of rTMS using magnetic fields that are orders of magnitude lower that those currently used in the clinic. We discuss how extensive characterisation of "low intensity" rTMS has set the stage for translation of new rTMS parameters from a mechanistic evidence base, with potential for innovative and effective therapeutic applications. Low-intensity rTMS demonstrates neurobiological effects across healthy and disease models, which include depression, injury and regeneration, abnormal circuit organisation, tinnitus etc. Various short and long-term changes to metabolism, neurotransmitter release, functional connectivity, genetic changes, cell survival and behaviour have been investigated and we summarise these key changes and the possible mechanisms behind them. Mechanisms at genetic, molecular, cellular and system levels have been identified with evidence that low-intensity rTMS and potentially rTMS in general acts through several key pathways to induce changes in the brain with modulation of internal calcium signalling identified as a major mechanism. We discuss the role that preclinical models can play to inform current clinical research as well as uncover new pathways for investigation.

Effects of electromagnetic fields on neuronal ion channels: a systematic review

Many aspects of chemistry and biology are mediated by electromagnetic field (EMF) interactions. The central nervous system (CNS) is particularly sensitive to EMF stimuli. Studies have explored the direct effect of different EMFs on the electrical properties of neurons in the last two decades, particularly focusing on the role of voltage-gated ion channels (VGCs). This work aims to systematically review published evidence in the last two decades detailing the effects of EMFs on neuronal ion channels as per the PRISM guidelines. Following a predetermined exclusion and inclusion criteria, 22 papers were included after searches on three online databases. Changes in calcium homeostasis, attributable to the voltage-gated calcium channels, were found to be the most commonly reported result of EMF exposure. EMF effects on the neuronal landscape appear to be diverse and greatly dependent on parameters, such as the field's frequency, exposure time, and intrinsic properties of the irradiated tissue, such as the expression of VGCs. Here, we systematically clarify how neuronal ion channels are particularly affected and differentially modulated by EMFs at multiple levels, such as gating dynamics, ion conductance, concentration in the membrane, and gene and protein expression. Ion channels represent a major transducer for EMF-related effects on the CNS.

Extremely Low-Frequency Magnetic Field as a Stress Factor-Really Detrimental?-Insight into Literature from the Last Decade

Biological effects of extremely low-frequency magnetic field (ELF-MF) and its consequences on human health have become the subject of important and recurrent public debate. ELF-MF evokes cell/organism responses that are characteristic to a general stress reaction, thus it can be regarded as a stress factor. Exposure to ELF-MF "turns on" different intracellular mechanisms into both directions: compensatory or deleterious ones. ELF-MF can provoke morphological and physiological changes in stress-related systems, mainly nervous, hormonal, and immunological ones. This review summarizes the ELF-MF-mediated changes at various levels of the organism organization. Special attention is placed on the review of literature from the last decade. Most studies on ELF-MF effects concentrate on its negative influence, e.g., impairment of behavior towards depressive and anxiety disorders; however, in the last decade there was an increase in the number of research studies showing stimulating impact of ELF-MF on neuroplasticity and neurorehabilitation. In the face of numerous studies on the ELF-MF action, it is necessary to systematize the knowledge for a better understanding of the phenomenon, in order to reduce the risk associated with the exposure to this factor and to recognize the possibility of using it as a therapeutic agent.

Alternating Electric Fields (TTFields) Activate Cav1.2 Channels in Human Glioblastoma Cells

Tumor treating fields (TTFields) represent a novel FDA-approved treatment modality for patients with newly diagnosed or recurrent glioblastoma multiforme. This therapy applies intermediate frequency alternating electric fields with low intensity to the tumor volume by the use of non-invasive transducer electrode arrays. Mechanistically, TTFields have been proposed to impair formation of the mitotic spindle apparatus and cytokinesis. In order to identify further potential molecular targets, here the effects of TTFields on Ca²⁺-signaling, ion channel activity in the plasma membrane, cell cycle, cell death, and clonogenic survival were tested in two human glioblastoma cell lines in vitro by fura-2 Ca²⁺ imaging, patch-clamp cell-attached recordings, flow cytometry and pre-plated colony formation assay. In addition, the expression of voltage-gated Ca²⁺ (Ca_v) channels was determined by real-time RT-PCR and their significance for the cellular TTFields response defined by knock-down and pharmacological blockade. As a result, TTFields stimulated in a cell line-dependent manner a Ca_v1.2-mediated Ca²⁺ entry, G₁ or S phase cell cycle arrest, breakdown of the inner mitochondrial membrane potential and DNA degradation, and/or decline of clonogenic survival suggesting a tumoricidal action of TTFields. Moreover, inhibition of Ca_v1.2 by benidipine aggravated in one glioblastoma line the TTFields effects suggesting that Ca_v1.2-triggered signaling contributes to cellular TTFields stress response. In conclusion, the present study identified Ca_v1.2 channels as TTFields target in the plasma membrane and provides the rationale to combine TTFields therapy with Ca²⁺ antagonists that are already in clinical use.

The expression of pluripotency and neuronal differentiation markers under the influence of electromagnetic field and nitric oxide

Nitric oxide (NO) is a diatomic free radical compound that as a secondary messenger contributes to cell physiological functions and its variations influence proteins activity and triggering intracellular signaling cascades. Low frequency electromagnetic field (EMF) alters the cell biology such as cell differentiation by targeting the plasma membrane and entering force to the ions and small electrical ligands. The effect of these chemical (NO) and physical (EMF) factors on the expression of the stemness and neuronal differentiation markers in rat bone marrow mesenchymal stem cells (BMSC) was investigated. The cells were treated with low (50micromolar) and high (1mM) concentrations of Deta-NO as a NO donor molecule and 50Hz low frequency EMF. The expression of pluripotency and neuronal differentiation genes and proteins was investigated using real time qPCR and Immunocytochemistry techniques. The simultaneous treatment of EMF with NO (1mM) led to the down-regulation of stemness markers expression and up-regulation of neuronal differentiation markers expression. Cell proliferation decreased and cell morphology changed which caused the majority of cells obtains neuronal protein markers in their cytoplasm. The decrease in the expression of neuronal differentiation Nestin and DCX markers without any change in the expression of pluripotency Oct4 marker (treated with low concentration of NO) indicates protection of stemness state in these cells. Treatment with NO demonstrated a double behavior. NO low concentration helped the cells protect the stemness state but NO high concentration plus EMF pushed cells into differentiation pathway.

The effects of 50 Hz magnetic field exposure on DNA damage and cellular functions in various neurogenic cells

Epidemiological studies have indicated a possible association between extremely low-frequency magnetic field (ELF-MF) exposure and the risk of nervous system diseases. However, laboratory studies have not provided consistent results for clarifying this association, despite many years of studies. In this study, we have systematically investigated the effects of 50 Hz MF exposure on DNA damage and cellular functions in both neurogenic tumor cell lines (U251, A172, SH-SY5Y) and primary cultured neurogenic cells from rats (astrocytes, microglia, cortical neurons). The results showed that exposure to a 50 Hz MF at 2.0 mT for up to 24 h did not influence γH2AX foci formation (an early marker of DNA double-strand breaks) in any of six different neurogenic cells. Exposure to a 50 Hz MF did not affect cell cycle progression, cell proliferation or cell viability in neurogenic tumor U251, A172 or SH-SY5Y cells. Furthermore, the MF exposure for 24 h did not significantly affect the secretion of cytokines (TNF-α, IL-6 or IL-1β) in astrocytes or microglia, or the phagocytic activity of microglia. In addition, MF exposure for 1 h per day did not significantly influence expression levels of microtubule-associated protein tau, microtubule-associated protein 2, postsynaptic density 95 or gephyrin in cortical neurons, indicating an absence of effects of MF exposure on the development of cortical neurons. In conclusion, our data suggest that exposure to a 50 Hz MF at 2.0 mT did not elicit DNA damage effects or abnormal cellular functions in the neurogenic cells studied.

Calcium homeostasis and low-frequency magnetic and electric field exposure: A systematic review and meta-analysis of in vitro studies

Low frequency magnetic field (LF MF) exposure is recurrently suggested to have the ability to induce health effects in society. Therefore, in vitro model systems are used to investigate biological effects of exposure. LF MF induced changes of the cellular calcium homeostasis are frequently hypothesised to be the possible target, but this hypothesis is both substantiated and rejected by numerous studies in literature. Despite the large amount of data, no systematic analysis of in vitro studies has been conducted to address the strength of evidence for an association between LF MF exposure and calcium homeostasis. Our systematic review, with inclusion of 42 studies, showed evidence for an association of LF MF with internal calcium concentrations and calcium oscillation patterns. The oscillation frequency increased, while the amplitude and the percentage of oscillating cells remained constant. The intracellular calcium concentration increased (SMD 0.351, 95% CI 0.126, 0.576). Subgroup analysis revealed heterogeneous effects associated with the exposure frequency, magnetic flux density and duration. Moreover, we found support for the presence of MF-sensitive cell types. Nevertheless, some of the included studies may introduce a great risk of bias as a result of uncontrolled or not reported exposure conditions, temperature ranges and ambient fields. In addition, mathematical calculations of the parasitic induced electric fields (IEFs) disclosed their association with increased intracellular calcium. Our results demonstrate that LF MF might influence the calcium homeostasis in cells in vitro, but the risk of bias and high heterogeneity (I(2)>75%) weakens the analyses. Therefore any potential clinical implications await further investigation.

Neuroprotective effects of lotus seedpod procyanidins on extremely low frequency electromagnetic field-induced neurotoxicity in primary cultured hippocampal neurons

The present study investigated the protective effects of lotus seedpod procyanidins (LSPCs) on extremely low frequency electromagnetic field (ELF-EMF)-induced neurotoxicity in primary cultured rat hippocampal neurons and the underlying molecular mechanism. The results of MTT, morphological observation, superoxide dismutase (SOD) and malondialdehyde (MDA) assays showed that compared with control, incubating neurons under ELF-EMF exposure significantly decreased cell viability and increased the number of apoptotic cells, whereas LSPCs evidently protected the hippocampal neurons against ELF-EMF-induced cell damage. Moreover, a certain concentration of LSPCs inhibited the elevation of intracellular reactive oxygen species (ROS) and Ca(2+) level, as well as prevented the disruption of mitochondrial membrane potential induced by ELF-EMF exposure. In addition, supplementation with LSPCs could alleviate DNA damage, block cell cycle arrest at S phase, and inhibit apoptosis and necrosis of hippocampal neurons under ELF-EMF exposure. Further study demonstrated that LSPCs up-regulated the activations of Bcl-2, Bcl-xl proteins and suppressed the expressions of Bad, Bax proteins caused by ELF-EMF exposure. In conclusion, these findings revealed that LSPCs protected against ELF-EMF-induced neurotoxicity through inhibiting oxidative stress and mitochondrial apoptotic pathway.