Pulsed Electromagnetic Field Assisted in vitro Electroporation: A Pilot Study

Preliminary Exploration of the Biophysical Mechanisms of Pulsed Magnetic Field- Induced Cell Permeabilization

Pulsed magnetic field treatment can enhance cell membrane permeability, allowing large molecular substances that normally cannot pass through the cell membrane to enter the cell. This research holds significant prospects for biomedical applications. However, the mechanism underlying pulsed magnetic field-induced cell permeabilization remains unclear, impeding further progress in research related to pulsed magnetic field. Currently, hypotheses about the mechanism are struggling to explain experimental results. Therefore, this study developed a parameter-adjustable pulsed magnetic field generator and designed experiments. Starting from the widely accepted hypothesis of "induced electric fields by pulsed magnetic field," we conducted a preliminary exploration of the biophysical mechanisms underlying pulsed magnetic field-induced cell permeabilization. Finally, we have arrived at an intriguing conclusion: under the current technical parameters, the impact of the pulsed magnetic field itself is the primary factor influencing changes in cell membrane permeability, rather than the induced electric field. This conclusion holds significant implications for understanding the biophysical mechanisms behind pulsed magnetic field therapy and its potential biomedical applications.

Microgreens and novel non-thermal seed germination techniques for sustainable food systems: a review

There are a number of cutting-edge techniques implemented in the germination process, including high pressure processing, ultrasonic, ultraviolet, light, non-thermal plasma, magnetic field, microwave radiation, electrolyzed oxidizing water, and plasma activated water. The influence of these technological advances on seed germination procedure is addressed in this review. The use of these technologies has several benefits, including the enhancement of plant growth rate and the modulation of bioactive chemicals like ABA, protein, and peroxidase concentrations, as well as the suppression of microbial development. Microgreens' positive health effects, such as their antioxidant, anticancer, antiproliferative/pro-oxidant, anti-obesity, and anti-inflammatory properties are extensively reviewed. The phytochemical and bioactive components of microgreens were investigated, including the concentrations of vitamin K, vitamin C, vitamin E, micro and macro nutrients, pro-vitamin A, polyphenols, and glucosinolates. Furthermore, the potential commercial uses of microgreens, as well as the current market transformation and prospects for the future are explored.

Time-Delayed Anticancer Effect of an Extremely Low Frequency Alternating Magnetic Field and Multimodal Protein-Tannin-Mitoxantrone Carriers with Brillouin Microspectroscopy Visualization In Vitro

The effect of an extremely low frequency alternating magnetic field (ELF AMF) at frequencies of 17, 48, and 95 Hz at 100 mT on free and internalized 4T1 breast cancer cell submicron magnetic mineral carriers with an anticancer drug, mitoxantrone, was shown. The alternating magnetic field (100 mT; 17, 48, 95 Hz; time of treatment-10.5 min with a 30 s delay) does not lead to the significant destruction of carrier shells and release of mitoxantrone or bovine serum albumin from them according to the data of spectrophotometry, or the heating of carriers in the process of exposure to magnetic fields. The most optimal set of factors that would lead to the suppression of proliferation and survival of cells with anticancer drug carriers on the third day (in comparison with the control and first day) is exposure to an alternating magnetic field of 100 mT in a pulsed mode with a frequency of 95 Hz. The presence of magnetic nanocarriers in cell lines was carried out by a direct label-free method, space-resolved Brillouin light scattering (BLS) spectrometry, which was realized for the first time. The analysis of the series of integrated BLS spectra showed an increase in the magnetic phase in cells with a growth in the number of particles per cell (from 10 to 100) after their internalization. The safety of magnetic carriers in the release of their constituent ions has been evaluated using atomic absorption spectrometry.

Polyphenol Extraction from Food (by) Products by Pulsed Electric Field: A Review

Nowadays, more and more researchers engage in studies regarding the extraction of bioactive compounds from natural sources. To this end, plenty of studies have been published on this topic, with the interest in the field growing exponentially. One major aim of such studies is to maximize the extraction yield and, simultaneously, to use procedures that adhere to the principles of green chemistry, as much as possible. It was not until recently that pulsed electric field (PEF) technology has been put to good use to achieve this goal. This new technique exhibits many advantages, compared to other techniques, and they have successfully been reaped for the production of extracts with enhanced concentrations in bioactive compounds. In this advancing field of research, a good understanding of the existing literature is mandatory to develop more advanced concepts in the future. The aim of this review is to provide a thorough discussion of the most important applications of PEF for the enhancement of polyphenols extraction from fresh food products and by-products, as well as to discuss the current limitations and the prospects of the field.

Technological innovations enhance postharvest fresh food resilience from a supply chain perspective

Fresh food is rich in nutrients but is usually seasonal, perishable, and challenging to store without degradation of quality. The inherent limitations of various preservation technologies can result in losses in all stages of the supply chain. As consumers of fresh foods have become more health-conscious, new technologies for intelligent, energy-efficient, and nondestructive preservation and processing have emerged as a research priority in recent years. This review aims to summarize the quality change characteristics of postharvest fruits, vegetables, meats, and aquatic products. It critically analyzes research progress and applications of various emerging technologies, which include: the application of high-voltage electric field, magnetic field, electromagnetic field, plasma, electrolytic water, nanotechnology, modified atmosphere packaging, and composite bio-coated film preservation technologies. An evaluation is presented of the benefits and drawbacks of these technologies, as well as future development trends. Moreover, this review provides guidance for design of the food supply chain to take advantage of various technologies used to process food, reduce losses and waste of fresh food, and this improve the overall resilience of the supply chain.

Chemotherapy and Physical Therapeutics Modulate Antigens on Cancer Cells

Cancer cells possess specific properties, such as multidrug resistance or unlimited proliferation potential, due to the presence of specific proteins on their cell membranes. The release of proliferation-related proteins from the membrane can evoke a loss of adaptive ability in cancer cells and thus enhance the effects of anticancer therapy. The upregulation of cancer-specific membrane antigens results in a better outcome of immunotherapy. Moreover, cytotoxic T-cells may also become more effective when stimulated ex-vivo toward the anticancer response. Therefore, the modulation of membrane proteins may serve as an interesting attempt in anticancer therapy. The presence of membrane antigens relies on various physical factors such as temperature, exposure to radiation, or drugs. Therefore, changing the tumor microenvironment conditions may lead to cancer cells becoming sensitized to subsequent therapy. This paper focuses on the therapeutic approaches modulating membrane antigens and enzymes in anticancer therapy. It aims to analyze the possible methods for modulating the antigens, such as pharmacological treatment, electric field treatment, photodynamic reaction, treatment with magnetic field or X-ray radiation. Besides, an overview of the effects of chemotherapy and immunotherapy on the immunophenotype of cancer cells is presented. Finally, the authors review the clinical trials that involved the modulation of cell immunophenotype in anticancer therapy.

Gold nanoparticles as enablers of cell membrane permeabilization by time-varying magnetic field: influence of distance and geometry

This study is based on the quantification of the influence of the presence of gold nanoparticles (Au NPs), of their geometry and their distance from cell membrane during time-varying electromagnetic fields cell membrane permeabilization on the pores opening dynamics. Results showed that the combined use of Au NPs and time-varying magnetic field can improve significantly the permeabilization of cell membrane. The presence of Au NPs allowed to reach transmembrane potential values enabling the cell membrane permeabilization only when placed at very short distance, equal to 20 nm. Both geometry and variability of the positioning in proximity of the cell membrane showed a strong influence on the probability of enabling pores opening. Clinical Relevance- This study provides a better comprehension about the mechanisms, still not completely understood, underlying cell membrane permeabilization by combining Au NPs and time-varying magnetic fields.

Pulsed Electromagnetic Field (PEMF) Treatment Reduces Lipopolysaccharide-Induced Septic Shock in Mice

Despite advances in medicine, mortality due to sepsis has not decreased. Pulsed electromagnetic field (PEMF) therapy is emerging as an alternative treatment in many inflammation-related diseases. However, there are few studies on the application of PEMF therapy to sepsis. In the current study, we examined the effect of PEMF therapy on a mouse model of lipopolysaccharide (LPS)-induced septic shock. Mice injected with LPS and treated with PEMF showed higher survival rates compared with the LPS group. The increased survival was correlated with decreased levels of pro-inflammatory cytokine mRNA expression and lower serum nitric oxide levels and nitric oxide synthase 2 mRNA expression in the liver compared with the LPS group. In the PEMF + LPS group, there was less organ damage in the liver, lungs, spleen, and kidneys compared to the LPS group. To identify potential gene targets of PEMF treatment, microarray analysis was performed, and the results showed that 136 genes were up-regulated, and 267 genes were down-regulated in the PEMF + LPS group compared to the LPS group. These results suggest that PEMF treatment can dramatically decrease septic shock through the reduction of pro-inflammatory cytokine gene expression. In a clinical setting, PEMF may provide a beneficial effect for patients with bacteria-induced sepsis and reduce septic shock-induced mortality.

In Vitro and in Vivo Study of the Effect of Osteogenic Pulsed Electromagnetic Fields on Breast and Lung Cancer Cells

Introduction: Although there have been significant advances in research and treatments over the past decades, cancer remains a leading cause of morbidity and mortality, mostly due to resistance to standard therapies. Pulsed electromagnetic field (PEMF), a newly emerged therapeutic strategy, has been highly regarded as less invasive and almost safe to patients, is now a clinically accepted form to treat diseases including cancer. Breast and lung cancer are the most prevalent forms of human cancers, yet reported investigations on exploring regimes including PEMF are limited. Methods: Intended to examine the anti-tumor effects of a clinically accepted osteogenic PEMF and the possibility of including PEMF in breast and lung cancer treatments, we studied the effects of 2 PEMF signals (PMF1 and PMF2) on breast and lung cancer cell growth and proliferation, as well as the possible underline mechanisms in vitro and in vivo. Results: We found that both signals caused modest but significant growth inhibition (∼5%) in MCF-7 and A549 cancer cells. Interestingly, mice xenograft tumors with A549 cells treated by PEMF were smaller in sizes than controls. However, for mice with MCF-7 tumor implants, treatment with PMF1 resulted in a slight increase (2.8%) in mean tumor size, while PMF2 treated tumors showed a 9% reduction in average size. Furthermore, PEMF increased caspase 3/7 expression levels and percentage of annexin stained cells, indicating the induction of apoptosis. It also increased G0 by 8.5%, caused changes in the expression of genes associated with cell growth suppression, DNA damage, cell cycle arrest, and apoptosis. When cancer cells or xenograft tumors treated with combined PEMF and chemotherapy drugs, PEMF showed growth inhibition effect independent of cisplatin in A549 cells, but with added effect by pemetrexed for the inhibition of MCF-7 growth. Conclusion: Together, our data suggested that clinically used osteogenic PEMF signals moderately suppressed cancer cell growth and proliferation both in vitro and in vivo.

Contactless Cell Permeabilization by Time-Varying Magnetic fields: Modelling Transmembrane Potential and Mechanical Stress in in- vitro Experimental Set-Up

The feasibility of using time-varying magnetic field as a contactless cells permeabilization method was demonstrated by experimental results, but the underlying mechanism is still poorly understood. In this study a numerical analysis of the transmembrane potential (TMP) at cell membranes during permeabilization by time-varying magnetic fields was proposed, and a first quantification of mechanical stress induced by the magnetic and electric fields and hypothesized to play an important role in the permeabilization mechanism was carried out. TMP values induced by typical in-vitro experimental conditions were far below the values needed for membrane permeabilization, with a strong dependence on distance of the cell from the coil. The preliminary assessment of the mechanical pressure and potential deformation of cells showed that stress values evaluated in conditions in which TMP values were too low to cause membrane permeabilization were comparable to those known to influence the pore opening mechanisms.Clinical Relevance- Results represent a significant step towards a better comprehension of the mechanism underlying cell membrane permeabilization by time-varying magnetic fields.

Cell transmembrane potential in contactless permeabilization by time-varying magnetic fields

BACKGROUND

Although experimental results proved the feasibility of using time-varying magnetic field as a contactless cells permeabilization method, the underlying mechanism is still poorly understood. In this study a numerical analysis of the time-dependent transmembrane potential (TMP) at cell membranes during permeabilization by time-varying magnetic fields was proposed, and a first quantification of mechanical stress induced by the magnetic and electric fields, hypothesized to play an important role in the permeabilization mechanism, was carried out.

METHODS

Starting from the simulation of real in vitro experimental conditions, the analysis was widened quantifying the influence of pulse frequency, cell dimension and distance of the cell from the magnetic field source. The mechanical pressure on cell membrane due to the interaction between free charges and induced electric field and due to the gradient of the magnetic field was quantified in all those conditions in which the TMP values were not high enough to cause membrane permeabilization.

RESULTS

TMP values induced by typical in-vitro experimental conditions were far below the values needed for membrane permeabilization, with a strong dependence on pulse frequency and distance of the cell from the coil.

CONCLUSION

The preliminary assessment of the mechanical pressure on cell membrane showed that stress values evaluated in conditions in which TMP values were too low to cause membrane permeabilization were comparable to those known to influence the pores opening mechanisms. Results represent a significant step towards a better comprehension of the mechanism underlying cell membrane permeabilization by time-varying magnetic fields.

A review of emerging physical transfection methods for CRISPR/Cas9-mediated gene editing

Gene editing is a versatile technique in biomedicine that promotes fundamental research as well as clinical therapy. The development of Clustered Regularly Interspaced Short Palindromic Repeats (CRISPR) as a genome editing machinery has accelerated the application of gene editing. However, the delivery of CRISPR components often suffers when using conventional transfection methods, such as viral transduction and chemical vectors, due to limited packaging size and inefficiency toward certain cell types. In this review, we discuss physical transfection methods for CRISPR gene editing which can overcome these limitations. We outline different types of physical transfection methods, highlight novel techniques to deliver CRISPR components, and emphasize the role of micro and nanotechnology to improve transfection performance. We present our perspectives on the limitations of current technology and provide insights on the future developments of physical transfection methods.

Microfluidic Irreversible Electroporation-A Versatile Tool to Extract Intracellular Contents of Bacteria and Yeast

Exploring the dynamic behavior of cellular metabolism requires a standard laboratory method that guarantees rapid sampling and extraction of the cellular content. We propose a versatile sampling technique applicable to cells with different cell wall and cell membrane properties. The technique is based on irreversible electroporation with simultaneous quenching and extraction by using a microfluidic device. By application of electric pulses in the millisecond range, permanent lethal pores are formed in the cell membrane of Escherichia coli and Saccharomyces cerevisiae, facilitating the release of the cellular contents; here demonstrated by the measurement of glucose-6-phosphate and the activity of the enzyme glucose-6-phosphate dehydrogenase. The successful application of this device was demonstrated by pulsed electric field treatment in a flow-through configuration of the microfluidic chip in combination with sampling, inactivation, and extraction of the intracellular content in a few seconds. Minimum electric field strengths of 10 kV/cm for E. coli and 7.5 kV/cm for yeast S. cerevisiae were required for successful cell lysis. The results are discussed in the context of applications in industrial biotechnology, where metabolomics analyses are important.

Membrane-permeabilized sonodynamic therapy enhances drug delivery into macrophages

Macrophages play a pivotal role in the formation and development of atherosclerosis as a predominant inflammatory cell type present within atherosclerotic plaque. Promoting anti-atherosclerotic drug delivery into macrophages may provide a therapeutic potential on atherosclerotic plaque. In this study, we investigated whether membrane-permeabilized sonodynamic therapy (MP-SDT) enhances drug delivery into THP-1 macrophages. Images of confocal microscopy confirmed that the optimal plasma distribution of the sonosensitizer protoporphyrin IX (PpIX) was at 1 hour incubation. The non-lethal parameter of MP-SDT was determined by cell viability as measured by a CCK-8 assay. Bright field microscopy demonstrated plasma membrane deformation in response to MP-SDT. Using SYTOX Green, a model drug for cellular uptake, we found that MP-SDT significantly induced membrane permeabilization dependent on ultrasound intensity and exposure time. Using Fluo-3 AM, intracellular calcium elevation during MP-SDT was confirmed as a result of membrane permeabilization. Membrane perforation of MP-SDT-treated cells was observed by scanning electron microscopy and transmission electron microscopy. Moreover, MP-SDT-induced membrane permeabilization and perforation were remarkably prevented by scavenging reactive oxygen species (ROS) during MP-SDT. Furthermore, we assessed the therapeutic effect of MP-SDT in combination with anti-atherosclerotic drug atorvastatin. Our results showed that MP-SDT increased the therapeutic effect of atorvastatin on lipid-laden THP-1-derived foam cells, including decreasing lipid droplets, increasing the cholesterol efflux and the expression of PPARγ and ABCG1. In conclusion, MP-SDT might become a promising approach to facilitating the delivery of anti-atherosclerotic drugs into macrophages via membrane permeabilization.

Effects of 5-HT1 and 5-HT 2 Receptor Agonists on Electromagnetic Field-Induced Analgesia in Rats

Much evidence demonstrates the antinociceptive effect of magnetic fields (MFs). However, the analgesic action mechanism of the electromagnetic field (EMF) is not exactly understood. The aim of the present study was to investigate the effects of 5-HT₁ and 5-HT₂ receptor agonists (serotonin HCl and 2,5-dimethoxy-4-iodoamphetamine [DOI] hydrochloride) on EMF-induced analgesia. In total, 66 adult male Wistar albino rats with an average body mass of 225 ± 13 g were used in this study. The animals were subjected to repeated exposures of alternating 50 Hz and 5 mT EMF for 2 h a day for 15 days. Prior to analgesia tests, serotonin HCl (5-HT₁ agonist) 4 mg/kg, WAY 100635 (5-HT₁ antagonist) 0.04 mg/kg, DOI hydrochloride (5-HT₂ receptor agonist) 4 mg/kg, and SB 204741 (5-HT₂ antagonist) 0.5 mg/kg doses were injected into rats. For statistical analysis of the data, analysis of variance was used and multiple comparisons were determined by Tukey's test. Administration of serotonin HCl MF (5 mT)-exposed rats produced a significant increase in percent maximal possible effect (% MPE) as compared with EMF group (P < 0.05). On the contrary, injection of WAY 100635 to MF-exposed rats produced a significant decrease in analgesic activity (P < 0.05). Similarly, the administration of DOI hydrochloride significantly increased % MPE values as compared with the EMF group while SB 204741 reduced it (P < 0.05). In conclusion, our results suggested that serotonin 5-HT₁ and 5-HT₂ receptors play an important role in EMF-induced analgesia; however, further research studies are necessary to understand the mechanism. Bioelectromagnetics. 2019;40:319-330. © 2019 Bioelectromagnetics Society.

Overcoming Antimicrobial Resistance in Bacteria Using Bioactive Magnetic Nanoparticles and Pulsed Electromagnetic Fields

Nisin is a known bacteriocin, which exhibits a wide spectrum of antimicrobial activity, while commonly being inefficient against Gram-negative bacteria. In this work, we present a proof of concept of novel antimicrobial methodology using targeted magnetic nisin-loaded nano-carriers [iron oxide nanoparticles (NPs) (11-13 nm) capped with citric, ascorbic, and gallic acids], which are activated by high pulsed electric and electromagnetic fields allowing to overcome the nisin-resistance of bacteria. As a cell model the Gram-positive bacteria Bacillus subtilis and Gram-negative Escherichia coli were used. We have applied 10 and 30 kV cm-1 electric field pulses (100 μs × 8) separately and in combination with two pulsed magnetic field protocols: (1) high dB/dt 3.3 T × 50 and (2) 10 mT, 100 kHz, 2 min protocol to induce additional permeabilization and local magnetic hyperthermia. We have shown that the high dB/dt pulsed magnetic fields increase the antimicrobial efficiency of nisin NPs similar to electroporation or magnetic hyperthermia methods and a synergistic treatment is also possible. The results of our work are promising for the development of new methods for treatment of the drug-resistant foodborne pathogens to minimize the risks of invasive infections.

Membrane permeabilization of mammalian cells using bursts of high magnetic field pulses

BACKGROUND

Cell membrane permeabilization by pulsed electromagnetic fields (PEMF) is a novel contactless method which results in effects similar to conventional electroporation. The non-invasiveness of the methodology, independence from the biological object homogeneity and electrical conductance introduce high flexibility and potential applicability of the PEMF in biomedicine, food processing, and biotechnology. The inferior effectiveness of the PEMF permeabilization compared to standard electroporation and the lack of clear description of the induced transmembrane transport are currently of major concern.

METHODS

The PEMF permeabilization experiments have been performed using a 5.5 T, 1.2 J pulse generator with a multilayer inductor as an applicator. We investigated the feasibility to increase membrane permeability of Chinese Hamster Ovary (CHO) cells using short microsecond (15 µs) pulse bursts (100 or 200 pulses) at low frequency (1 Hz) and high dB/dt (>10⁶ T/s). The effectiveness of the treatment was evaluated by fluorescence microscopy and flow cytometry using two different fluorescent dyes: propidium iodide (PI) and YO-PRO®-1 (YP). The results were compared to conventional electroporation (single pulse, 1.2 kV/cm, 100 µs), i.e., positive control.

RESULTS

The proposed PEMF protocols (both for 100 and 200 pulses) resulted in increased number of permeable cells (70 ± 11% for PI and 67 ± 9% for YP). Both cell permeabilization assays also showed a significant (8 ± 2% for PI and 35 ± 14% for YP) increase in fluorescence intensity indicating membrane permeabilization. The survival was not affected.

DISCUSSION

The obtained results demonstrate the potential of PEMF as a contactless treatment for achieving reversible permeabilization of biological cells. Similar to electroporation, the PEMF permeabilization efficacy is influenced by pulse parameters in a dose-dependent manner.

Membrane Permeabilization of Pathogenic Yeast in Alternating Sub-microsecond Electromagnetic Fields in Combination with Conventional Electroporation

Recently, a novel contactless treatment method based on high-power pulsed electromagnetic fields (PEMF) was proposed, which results in cell membrane permeabilization effects similar to electroporation. In this work, a new PEMF generator based on multi-stage Marx circuit topology, which is capable of delivering 3.3 T, 0.19 kV/cm sub-microsecond pulses was used to permeabilize pathogenic yeast Candida albicans separately and in combination with conventional square wave electroporation (8-17 kV/cm, 100 μs). Bursts of 10, 25, and 50 PEMF pulses were used. The yeast permeabilization rate was evaluated using flow cytometric analysis and propidium iodide (PI) assay. A statistically significant (P < 0.05) combinatorial effect of electroporation and PEMF treatment was detected. Also the PEMF treatment (3.3 T, 50 pulses) resulted in up to 21% loss of yeast viability, and a dose-dependent additive effect with pulsed electric field was observed. As expected, increase of the dB/dt and subsequently the induced electric field amplitude resulted in a detectable effect solely by PEMF, which was not achievable before for yeasts in vitro.

High-throughput in situ cell electroporation microsystem for parallel delivery of single guide RNAs into mammalian cells

Arrayed genetic screens mediated by the CRISPR/Cas9 technology with single guide RNA (sgRNA) libraries demand a high-throughput platform capable of transfecting diverse cell types at a high efficiency in a genome-wide scale for detection and analysis of sophisticated cellular phenotypes. Here we developed a high-throughput in situ cell electroporation (HiCEP) microsystem which leveraged the superhydrophobic feature of the microwell array to achieve individually controlled conditions in each microwell and coupled an interdigital electrode array chip with the microwells in a modular-based scheme for highly efficient delivery of exogenous molecules into cells. Two plasmids encoding enhanced green and red fluorescent proteins (EGFP and ERFP), respectively, were successfully electroporated into attached HeLa cells on a 169-microwell array chip with transfection efficiencies of 71.6 ± 11.4% and 62.9 ± 2.7%, and a cell viability above 95%. We also successfully conducted selective electroporation of sgRNA into 293T cells expressing the Cas9 nuclease in a high-throughput manner and observed the four-fold increase of the GFP intensities due to the repair of the protein coding sequences mediated by the CRISPR/Cas9 system. This study proved that this HiCEP system has the great potential to be used for arrayed functional screens with genome-wide CRISPR libraries on hard-to-transfect cells in the future.