Pulsed Electromagnetic Fields Stimulate HIF-1α-Independent VEGF Release in 1321N1 Human Astrocytes Protecting Neuron-Like SH-SY5Y Cells from Oxygen-Glucose Deprivation

From lab coats to clinical trials: Evolution and application of electromagnetic fields for ischemic stroke rehabilitation and monitoring

Stroke is a neurovascular disorder which stands as one of the leading causes of death and disability worldwide, resulting in motor and cognitive impairment. Although the treatment approach depends on the time elapsed, the type of stroke and the availability of care centers, common interventions include thrombectomy or the administration of a tissue plasminogen activator (tPA). While these methods restore blood flow, they fall short in helping patients regain lost function. With that, recent years have seen a rise in novel methods, one of which is the use of electromagnetic fields (EMFs). Due to their ability to impact the charges in their vicinity, thereby altering the immune response and cell signaling, EMFs became suitable candidates for stroke rehabilitation. Based on their characteristics, therapeutic EMFs can be categorized into transcranial magnetic stimulation (TMS), transcranial direct current stimulation (tDCS), pulsed (PEMFs) and low frequency (LF-EMFs) electromagnetic fields, among others. In addition to treatment, EMFs are being explored for stroke monitoring, utilizing external EMFs for imaging or recording innate EMFs linked to neural activity. Drawing from research on the effects of EMFs, this review aims to provide a comprehensive overview of the physical principles and molecular mechanisms underlying the action of EMFs, along with a discussion of their application in preclinical studies and clinical trials. Finally, this paper not only addresses the importance of treatment availability and potential side-effects, but also delves into the technical and ethical challenges associated with the use of EMFs, while exploring their prospects and future opportunities.

Effect of Low-Frequency, Low-Energy Pulsed Electromagnetic Fields in Neuronal and Microglial Cells Injured with Amyloid-Beta

Alzheimer's disease (AD) is a neurodegenerative pathology covering about 70% of all cases of dementia. It is associated with neuroinflammation and neuronal cell death, which are involved in disease progression. There is a lack of effective therapies, and halting this process represents a therapeutic challenge. Data in the literature suggest several neuroprotective effects of low-frequency, low-energy pulsed electromagnetic fields (PEMFs) on biological systems, and clinical studies report that PEMF stimulation is safe and well tolerated. The aim of this work is to investigate the effects of PEMF exposure on oxidative stress and cell death in in vitro-injured cellular models of neurons and microglia. SH-SY5Y cells were stimulated by hydrogen peroxide (H2O2) or amyloid-β (Aβ) peptide, and N9 microglial cells were activated with lipopolysaccharide (LPS) or Aβ peptide. Reactive oxygen production, mitochondrial integrity, and cell death modulation were investigated through 2',7'-dichlorodihydrofluorescein diacetate (H2DCFDA) and 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolocarbo-cyanine iodide (JC-1) biochemical assays, fluorescence, and MTS experiments. Cells were exposed to PEMFs producing a pulsed signal with the following parameters: pulse duration of 1.3 ms and frequency of 75 Hz. The outcomes demonstrated that PEMFs defended SH-SY5Y cells against Aβ peptide- or H2O2-induced oxidative stress, mitochondrial damage, and cell death. Furthermore, in microglia activated by LPS or Aβ peptide, they reverted the reduction in mitochondrial potential, oxidative damage, and cell death. Overall, these findings imply that PEMFs influence the redox state of the cells by significantly boosting antioxidant levels in both injured microglia and neuronal in vitro cells mimicking in vitro AD.

Orexin A protects against cerebral ischemia-reperfusion injury by enhancing reperfusion in ischemic cortex via HIF-1α-ET-1/eNOS pathway

The purpose of this study was to investigate the protective effect and underlying mechanism of orexin A on cerebral ischemia-reperfusion injury, specifically through vasodilation mediated by the hypoxia inducible factor-1α (HIF-1α)-Endothelin-1(ET-1)/endothelial nitric oxide synthase (eNOS) pathway. A model of middle cerebral artery occlusion was established in both wild-type SD rats with exogenous orexin A intervention and in orexin A transgenic rats. Neurological deficit scores and cerebral infarction areas were assessed, and ischemic cortical blood flow was monitored. Gene and protein expression levels of HIF-1α, HIF-2α, ET-1, and three types of NOS were detected using real-time RT-qPCR and Western blot analysis, respectively. Additionally, nitric oxide (NO) levels in the cortex were analyzed through biochemical detection methods. Orexin A demonstrated a protective effect by reducing cerebral infarction and improving neurological deficits, which was achieved by increasing cortical blood flow during reperfusion. This protective mechanism was associated with upregulated HIF-1α expression, downregulated ET-1 expression, upregulated eNOS expression, and increased NO production. This study demonstrates the protective effect of orexin A on cerebral ischemia-reperfusion injury, achieved by regulating the release of vasomotor substances to enhance cortical blood flow during reperfusion. These findings suggest that orexin A may represent a potential therapeutic strategy for ischemic stroke.

Immunomodulatory Behavior of Tendon Magnetic Cell Sheets can be Modulated in Hypoxic Environments under Magnetic Stimulus

Tissue environments play a crucial role in orchestrating cell behavior, guided by a complex interplay of various factors. Long lasting inflammatory signals compromise tendon homeostasis and promote tissue degeneration, while tissue oxygen levels affect local cells' responses with hypoxic environments influencing apoptosis, inflammatory mediators, and matrix production. Recent works have unveiled the therapeutic potential of pulsed electromagnetic field (PEMF) in modulating inflammatory signals expressed by human tendon cells (hTDCs), and in mitigating the hypoxia-induced effects on the regulation of inflammatory cytokines. Thus, we sought to investigate the role of hypoxic environments, namely, 1 and 2% oxygen tension, in the inflammatory profiles of magnetic cell sheets (magCSs) formed by magnetic nanoparticles internalized in contiguous hTDCs with intact cell-cell junctions and deposited matrix. We also aimed to explore the impact of PEMF over hypoxia-treated magCSs, including IL-1β-primed-magCSs, with the objective of harnessing magnetic stimulation to guide abnormal inflammatory cell responses toward efficient treatments supporting tendon regenerative potential. Our findings revealed that low oxygen tensions amplified the expression of hypoxia-associated genes and of inflammatory markers in IL-1β-primed-magCSs with an involvement of the NF-κB signaling pathway. Encouragingly, when PEMF was applied to IL-1β-primed-magCSs under hypoxic conditions, it successfully modulated inflammatory cues by favoring IL-10 and IL-4, via the NF-κB pathway. These results signify the remarkable potential of PEMF in driving proregenerative strategies and opens up new approaches in tendon therapies, highlighting the transformative impact of immunomodulatory magnetic cell sheets.

β-Caryophyllene Inhibits Endothelial Tube Formation by Modulating the Secretome of Hypoxic Lung Cancer Cells-Possible Role of VEGF Downregulation

β-Caryophyllene (BCP), a bicyclic sesquiterpene that is a component of the essential oils of various spice and food plants, has been described as a selective CB2 cannabinoid receptor agonist. In the present study, the effect of BCP on angiogenesis was investigated. It was found that conditioned media (CM) from BCP-treated hypoxic A549 lung cancer cells exhibited a concentration-dependent inhibitory effect on human umbilical vein endothelial cell (HUVEC) tube formation induced by CM from vehicle-treated hypoxic A549 cells. There was an associated concentration-dependent decrease in the proangiogenic factor vascular endothelial growth factor (VEGF) in the CM, with both BCP inhibitory effects (tube formation, VEGF secretion) being CB2 receptor-dependent. A reduction of the transcription factor hypoxia-inducible factor 1α (HIF-1α) was furthermore detected. The antiangiogenic and VEGF-lowering properties of BCP were confirmed when CM from another lung cancer cell line, H358, were tested. When directly exposed to HUVECs, BCP showed no significant effect on tube formation, but at 10 µM, impaired VEGF receptor 2 (VEGFR2) phosphorylation triggered by recombinant VEGF in a CB2 receptor-independent manner. In summary, BCP has a dual antiangiogenic effect on HUVECs, manifested in the inhibition of tube formation through modulation of the tumor cell secretome and additionally in the inhibition of VEGF-induced VEGFR2 activation. Because the CB2 agonist has no psychoactive properties, BCP should continue to be evaluated preclinically for further antitumor effects.

Positive effects of pulsed electromagnetic fields on behavior, immune function, and oxidative and inflammatory state in old mice

The establishment of chronic oxidative and inflammatory stress with aging leads to the deterioration of the nervous and immune systems and, consequently, to the loss of health. The aim of this work was to study the effect of exposure to low-frequency pulsed electromagnetic fields (PEMFs) produced by the NEURALTER® system (15 min/day for 4 weeks) in the behavior, immune functions, and oxidative and inflammatory state of old mice. Female old CD1 mice were divided into three groups: control group, handling control group and Neuralter group. Then, behavioral tests were performed, and peritoneal leukocytes were extracted to analyze function, oxidative and inflammatory parameters. In peritoneal leukocytes from old mice, the effects in vitro of 15 min with NEURALTER® were studied on function and oxidative parameters. The results show that after this type of treatment, old mice had greater coordination and locomotion, better immune function, and an oxidative-inflammatory state. Similarly, the immune function and oxidative state of leukocytes showed an improvement when these cells were exposed directly to the NEURALTER® system. In conclusion, the exposure to low-frequency PEMFs produced by the NEURALTER® system has beneficial effects on health in aging. In addition, this effect is direct, at least in part, on immune cells.

Pulsed Electromagnetic Fields Protect Against Brain Ischemia by Modulating the Astrocytic Cholinergic Anti-inflammatory Pathway

Neuroinflammation is one of the most important pathological processes following brain ischemia. Pulsed electromagnetic fields (PEMFs) protect against brain ischemia, but their role in regulating neuroinflammation remains unclear. In the present study, we investigated the biological effects of PEMF exposure on brain ischemia-induced neuroinflammation through the astrocytic cholinergic anti-inflammatory pathway. PEMF exposure reduced the activation of astrocytes and neuroinflammation following brain ischemia by directly modulating astrocytic injury and inflammatory cytokine release. Inhibition of nicotinic acetylcholine receptor alpha 7 subunit (α7nAChR) by a specific antagonist reversed the regulatory effects of PEMF on astrocytes. Furthermore, negative regulation of signal transducer and activator of transcription 3 (STAT3) by α7nAChR was found to be an important downstream mechanism through which PEMF regulates astrocyte-related neuroinflammation. PEMF suppressed STAT3 phosphorylation and nuclear translocation by activating α7nAChR. These results demonstrate that PEMF exerts anti-inflammatory effects in the context of brain ischemia by modulating astrocytic α7nAChR/STAT3 signaling.

Purinergic signaling: a potential therapeutic target for ischemic stroke

Pathogenesis of ischemic stroke is mainly characterized by thrombosis and neuroinflammation. Purinergic signaling pathway constitutes adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), and adenosine (ADO). ATP is hydrolyzed to ADP and then to AMP by extracellular nucleotidase CD39; AMP is subsequently converted to adenosine by CD73. All these nucleotides and nucleosides act on purinergic receptors protecting against thrombosis and inhibit inflammation. In addition, many physical methods have been found to play a neuroprotective role through purinergic signaling. This review mainly introduces the role and potential mechanism of purinergic signalings in the treatment of ischemic stroke, so as to provide reference for seeking new treatment methods for stroke.

Development of potent and selective FAAH inhibitors with improved drug-like properties as potential tools to treat neuroinflammatory conditions

The neuroprotective performance against neuroinflammation of the endocannabinoid system (ECS) can be remarkably improved by indirect stimulation mediated by the pharmacological inhibition of the key ECS catabolic enzyme fatty acid amide hydrolase (FAAH). Based on our previous works and aiming to discover new selective FAAH inhibitors , we herein reported a new series of carbamate-based FAAH inhibitors (4a-t) which showed improved drug disposition properties compared to the previously reported analogues 2a-b. The introduction of ionizable functions allowed us to obtain new FAAH inhibitors of nanomolar potency characterized by good water solubility and chemical stability at physiological pH. Interesting structure-activity relationships (SARs), deeply analyzed by molecular docking and molecular dynamic (MD) simulations, were obtained. All the newly developed inhibitors showed an excellent selectivity profile evaluated against monoacylglycerol lipase and cannabinoid receptors. The reversible mechanism of action was determined by a rapid dilution assay. Absence of toxicity was confirmed in mouse fibroblasts NIH3T3 (for compounds 4e, 4g, 4n-o, and 4s) and in human astrocytes cell line 1321N1 (for compounds 4e, 4n, and 4s). The absence of undesired cardiac effects was also confirmed for compound 4n. Selected analogues (compounds 4e, 4g, 4n, and 4s) were able to reduce oxidative stress in 1321N1 astrocytes and exhibited notable neuroprotective effects when tested in an ex vivo model of neuroinflammation.

Identification of Potential Ferroptosis Key Genes in the Pathogenesis of Lumbosacral Spinal Root Avulsion by RNA Sequencing and Bioinformatics Analysis

Objective: Ferroptosis is a type of cell death involved in various human diseases, including nerve injury. However, the role of ferroptosis in lumbosacral spinal root avulsion (LSRA) remains unknown. This study aims to investigate whether ferroptosis is induced after LSRA and the key ferroptosis-related genes and their potential function in LSRA.

Methods: The biochemical and morphological changes of ferroptosis were determined by detection of iron accumulation and by transmission electron microscopy in a rat LSRA model. The transcriptional expression profile following LSRA was investigated by RNA sequencing and ferroptosis-related genes were downloaded from FerrDb and used to identify ferroptosis differentially expressed genes (DEGs). The differential expressions of ferroptosis DEGs were confirmed by qRT-PCR analysis. The potential functions of ferroptosis DEGs were revealed by DAVID 6.8 and WebGestalt. A protein–protein interaction (PPI) network and gene–miRNA interaction network were further constructed to identify key modules in ferroptosis DEGs, and the results were verified by qRT-PCR and western blot analysis.

Results: LSRA was followed by ferroptosis-specific changes, such as shrunken mitochondria and increased iron accumulation, that can be alleviated by ferroptosis inhibitor deferoxamine (DFO). A total of 2,446 DEGs and 46 ferroptosis DEGs were identified after LSRA, and over 90% of the ferroptosis DEGs were confirmed to be differentially expressed following LSRA, which can also be eliminated by DFO treatment. Functional analysis demonstrated significant enrichment of the ferroptosis DEGs in pathways related to the oxidative stress response, the HIF-1 signaling pathway, and the tumor necrosis factor signaling pathway. PPI network analysis demonstrated that a set of key modules in ferroptosis DEGs were related to the HIF-1 signaling pathway: Il6, Nos2, Stat3, Hif1a, Vegfa, Cdkn1a, and Rela. Construction of a gene–miRNA network predicted miRNAs targeting four key ferroptosis DEGs—Stat3, Hif1a, Vegfa, and Rela, and further western blot analysis confirmed their upregulation after LSRA, which can be alleviated by DFO pretreatment.

Conclusion: The data revealed the induction of ferroptosis in a rat LSRA model and identified possible regulatory roles for ferroptosis-related genes in the molecular mechanisms of LSRA, which provides new insights into the pathogenesis and helps to find new molecular targets for the treatment of LSRA.

Electromagnetic Field as a Treatment for Cerebral Ischemic Stroke

Cerebral stroke is a leading cause of death and adult-acquired disability worldwide. To this date, treatment options are limited; hence, the search for new therapeutic approaches continues. Electromagnetic fields (EMFs) affect a wide variety of biological processes and accumulating evidence shows their potential as a treatment for ischemic stroke. Based on their characteristics, they can be divided into stationary, pulsed, and sinusoidal EMF. The aim of this review is to provide an extensive literature overview ranging from in vitro to even clinical studies within the field of ischemic stroke of all EMF types. A thorough comparison between EMF types and their effects is provided, as well as an overview of the signal pathways activated in cell types relevant for ischemic stroke such as neurons, microglia, astrocytes, and endothelial cells. We also discuss which steps have to be taken to improve their therapeutic efficacy in the frame of the clinical translation of this promising therapy.

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.