Nanosecond pulsed electric fields trigger cell differentiation in Chlamydomonas reinhardtii

Relationships of pulsed frequency and anammox bacteria growth rate, at low temperatures

This study explored pulsed frequency that could enhance the anammox bacteria growth rate and TN removal rate at low temperatures (16 ± 1°C). The results showed that the growth rate of anammox bacteria in R1 (1000 Hz) was significantly higher than in R2 (30 Hz) and R3 (106Hz). The relative abundance values of anammox bacteria R1 were higher by 52.21% and 172.41% than R2 and R3, while that of MLSS were as high as 241.07% and 471.36% than R2 and R3, with the nitrogen loading rate was 6.84 kg-N/m³/d. Besides, the dynamics also showed that the specific anammox activity (SAA) and the cellular yield of R1 were higher than R2 and R3. The intermediate frequency could enhance the cell division by stimulating the anammoxosome and reduce the ionic hydration layer to accelerate the ion migration rate, further improving the number of anammox bacteria even at low temperatures. The pulsed frequency could enhance the anammox growth rate and the doubling time is just 5 d.

Changes in Gene Expression After Exposing Arabidopsis thaliana Plants to Nanosecond High Amplitude Electromagnetic Field Pulses

The biological effects of exposure to electromagnetic fields due to wireless technologies and connected devices are a subject of particular research interest. Ultrashort high-amplitude electromagnetic field pulses delivered to biological samples using immersed electrodes in a dedicated cuvette have widely demonstrated their effectiveness in triggering several cell responses including increased cytosolic calcium concentration and reactive oxygen species (ROS) production. In contrast, the effects of these pulses are poorly documented when electromagnetic pulses are delivered through an antenna. Here we exposed Arabidopsis thaliana plants to 30,000 pulses (237  kV m-1 , 280 ps rise-time, duration of 500 ps) emitted through a Koshelev antenna and monitored the consequences of electromagnetic fields exposure on the expression levels of several key genes involved in calcium metabolism, signal transduction, ROS, and energy status. We found that this treatment was mostly unable to trigger significant changes in the messenger RNA accumulation of calmodulin, Zinc-Finger protein ZAT12, NADPH oxidase/respiratory burst oxidase homolog (RBOH) isoforms D and F, Catalase (CAT2), glutamate-cystein ligase (GSH1), glutathione synthetase (GSH2), Sucrose non-fermenting-related Kinase 1 (SnRK1) and Target of rapamycin (TOR). In contrast, Ascorbate peroxidases APX-1 and APX-6 were significantly induced 3 h after the exposure. These results suggest that this treatment, although quite strong in amplitude, is mostly ineffective in inducing biological effects at the transcriptional level when delivered by an antenna. © 2023 The Authors. Bioelectromagnetics published by Wiley Periodicals LLC on behalf of Bioelectromagnetics Society.

Enhancing single-cell bioconversion efficiency by harnessing nanosecond pulsed electric field processing

Nanosecond pulsed electric field (nsPEF) processing is gaining momentum as a physical means for single-cell bioconversion efficiency enhancement. The technology allows biomass yields per substrate (Y_X/S) to be leveraged and poses a viable option for stimulating intracellular compound production. NsPEF processing thus resonates with myriad domains spanning the pharmaceutical and medical sectors, as well as food and feed production. The exact working mechanisms underlying nsPEF-based enhancement of bioconversion efficiency, however, remain elusive, and a better understanding would be pivotal for leveraging process control to broaden the application of nsPEF and scale-up industrial implementation. To bridge this gap, the study provides the electrotechnological and metabolic fundamentals of nsPEF processing in the bio-based domain to enable a critical evaluation of pathways underlying the enhancement of single-cell bioconversion efficiency. Evidence suggests that treating cells during the rapid proliferating and thus the early to mid-exponential state of cellular growth is critical to promoting bioconversion efficiency. A combined effect of transient intracellular and sublethal stress induction and effects caused on the plasma membrane level result in an enhancement of cellular bioconversion efficiency. Congruency exists regarding the involvement of transient cytosolic Ca²⁺ hubs in nsPEF treatment responses, as well as that of reactive oxygen species formation culminating in the onset of cellular response pathways. A distinct assignment of single effects and their contributions to enhancing bioconversion efficiency, however, remains challenging. Current applications of nsPEF processing comprise microalgae, bacteria, and yeast biorefineries, but these endeavors are in their infancies with limitations associated with a lack of understanding of the underlying treatment mechanisms, an incomplete reporting, insufficient characterization, and control of processing parameters. The study aids in fostering the upsurge of nsPEF applications in the bio-based domain by providing a basis to gain a better understanding of cellular mechanisms underlying an nsPEF-based enhancement of cellular bioconversion efficiency and suggests best practice guidelines for nsPEF documentation for improved knowledge transfer. Better understanding and reporting of processes parameters and consequently improved process control could foster industrial-scale nsPEF realization and ultimately aid in perpetuating nsPEF applicability within the bio-based domain.

Nanosecond pulsed electrical fields enhance product recovery in plant cell fermentation

The potential of pharmacologically active secondary plant metabolites is limited by the low yield from often rare plants, and the lack of economically feasible chemical synthesis of these complex compounds. Plant cell fermentation offers an alternative strategy to overcome these constraints. However, the efficiency of this approach is limited by intracellular sequestration of the products, such that continuous bioprocessing is not possible. As a precondition for such a, more attractive, continuous process, it is of great importance to stimulate the export of the product into the medium without impairing viability and, thus, the productivity of the cells. Using nicotine alkaloids of tobacco as a case study, an alternative strategy is explored, where nanosecond pulsed electric fields (nsPEFs) are applied for the efficient downstream recovery of the products. To maintain cell viability and allow for the further use of biomass, cells were exposed to strong (1-20 kV·cm^-1), but very short (10-100 ns) electric pulses, which leads to a temporary permeabilisation of cell membranes. Using two transgenic cell lines, where two key genes involved in the metabolism of the anti-Alzheimer compound nornicotine were overexpressed, we could show that this nsPEF treatment improved the partitioning of some nicotine alkaloids to the culture medium without impairing viability, nor the synthesis of alkaloids. However, this release was only partial and did not work for nornicotine. Thus, nsPEFs produced a fractionation of alkaloids. We explain this electrofractionation by a working model considering the differential intracellular compartmentalization of nicotineic alkaloids.

Nanosecond pulsed electric fields modulate the expression of the astaxanthin biosynthesis genes psy, crtR-b and bkt 1 in Haematococcus pluvialis

Nanosecond pulsed electric fields (nsPEFs) have been extensively studied with respect to cellular responses. Whether nsPEFs can regulate gene expression and to modulate the synthesis of valuable compounds, has so far been only tested in the context of apoptosis in cancer cells. We used the unicellular algae Haematococcus pluvialis as system to test, whether nsPEFs could alter gene expression and to promote the biosynthesis of astaxanthin. We find that nsPEFs induce a mild, but significant increase of mortality up to about 20%, accompanied by a moderate increase of astaxanthin accumulation. Steady-state transcript levels of three key genes psy, crtR-b and bkt 1 were seen to increase with a maximum at 3 d after PEF treatment at 50 ns. Pulsing at 25 ns reduce the transcripts of psy, crtR-b from around day 2 after the pulse, while those of bkt 1 remain unchanged. By blocking the membrane-located NADPH oxidase RboH, diphenylene iodonium by itself increased both, the levels of astaxanthin and transcripts of all three biosynthetic genes, and this increase was added up to that produced by nsPEFs. Artificial calcium influx by an ionophore did not induce major changes in the accumulation of astaxanthin, nor in the transcript levels, but amplified the response of crtR-b to nsPEFs at 25 ns, while decreased in 50 ns treatment. When Ca²⁺ influx was inhibited by GdCl₃, the transcript of psy and bkt 1 were decreased for both 25 ns and 50 ns treatments, while crtR-b exhibited an obvious increase for the 25 ns treatment. We interpret these data in a working model, where nsPEFs permeabilise plasma and chloroplast membrane depending on pulse duration leading to a differential release of plastid retrograde signaling to the nucleus.

Nanosecond pulsed electric fields enhance mesenchymal stem cells differentiation via DNMT1-regulated OCT4/NANOG gene expression

Background

Multiple strategies have been proposed to promote the differentiation potential of mesenchymal stem cells (MSCs), which is the fundamental property in tissue formation and regeneration. However, these strategies are relatively inefficient that limit the application. In this study, we reported a novel and efficient strategy, nanosecond pulsed electric fields (nsPEFs) stimulation, which can enhance the trilineage differentiation potential of MSCs, and further explained the mechanism behind.

Methods

We used histological staining to screen out the nsPEFs parameters that promoted the trilineage differentiation potential of MSCs, and further proved the effect of nsPEFs by detecting the functional genes. In order to explore the corresponding mechanism, we examined the expression of pluripotency genes and the methylation status of their promoters. Finally, we targeted the DNA methyltransferase which was affected by nsPEFs.

Results

The trilineage differentiation of bone marrow-derived MSCs was significantly enhanced in vitro by simply pre-treating with 5 pulses of nsPEFs stimulation (energy levels as 10 ns, 20 kV/cm; 100 ns, 10 kV/cm), due to that the nsPEFs demethylated the promoters of stem cell pluripotency genes OCT4 and NANOG through instantaneous downregulation of DNA methylation transferase 1 (DNMT1), thereby increasing the expression of OCT4 and NANOG for up to 3 days, and created a treatment window period of stem cells.

Conclusions

In summary, nsPEFs can enhance MSCs differentiation via the epigenetic regulation and could be a safe and effective strategy for future stem cell application.

Bio-refinery of Chlorella sorokiniana with pulsed electric field pre-treatment

The aim of this work was to investigate the potential of PEF technology for green extraction of microalgal pigments and lipids from fresh Chlorella sorokiniana suspensions. Efficiencies of PEF treatment and different solvent systems application to C.sorokiniana were compared to efficiencies of untreated biomass extraction. Differences in chlorophyll extraction of untreated and PEF treated C.sorokiniana were only seen at short extraction times. Beneficial PEF-effect was minimised for long-time extractions of larger algae quantities where yields aligned. Extraction attempts on C. sorokiniana lipids did not show increased extractability after PEF treatment, which underlined the statement of PEF representing a rather ineffective disruption method for microalgae holding rigid cell walls.

Nano-Pulse Stimulation Induces Changes in the Intracellular Organelles in Rat Liver Tumors Treated In Situ

Background and Objectives

Nano‐pulse stimulation (NPS) therapy is the application of ultrafast pulses of high amplitude electrical energy to tissues to influence cell function. Unique characteristics of these pulses enable electric field penetration into the interior of cells and organelles to generate transient nanopores in both organelle and plasma membranes. The purpose of this study is to document the temporal and physical changes in intracellular organelles following NPS therapy using electron microscopy.

Study Design/Materials and Methods

Liver tumors were induced in five buffalo rats by implanting syngeneic McA‐RH7777 hepatocellular carcinoma cells into the surgically exposed livers. Tumors were allowed to grow for 1 week and then the surgically exposed livers were treated in situ with NPS energy delivered at a sufficient level to trigger regulated cell death in the tumor. Samples of NPS‐treated and control tissue were removed and fixed for electron microscopy at 1 minute, 5 minutes, 30 minutes, 2 hours and 4 hours after exposure.

Results

Measurements of cellular organelles indicate strong swelling following NPS therapy exposure compared with untreated controls. The mean diameter of the mitochondria increased by 55% within 1 minute and then by 2.5‐fold by 2 hours post‐NPS therapy. The rough endoplasmic reticulum (RER) cisternae swelled immediately after NPS therapy with reduced swelling by 30 minutes and loss of structural integrity by 2 hours. The Golgi apparatus appears swollen in images collected 1 and 5 minutes after NPS therapy and was no longer detected at 30 minutes and 2 hours post‐NPS therapy. By 4 hours after NPS therapy, a nascent Golgi apparatus was detected in many of the images. The plasma membrane lost its well‐defined morphology and became less linear, exhibiting discontinuities as early as 1 minute post‐NPS energy exposure and the nuclear envelope became subjectively less distinct over time.

Conclusions

NPS therapy at sufficient energy levels causes the rapid swelling of organelles, disintegration of the RER, breaks in the plasma membrane and blurs the borders of the nuclear envelope. These changes in the mitochondria and RER are indicative of a regulated cell death process. These immediate physical changes to vital cell organelles are likely to trigger subsequent regulated cell death mechanisms observed in other studies of NPS therapy. Lasers Surg. Med. © 2020 The Authors. Lasers in Surgery and Medicine published by Wiley Periodicals, Inc.

A dose-response study of a novel method of selective tissue modification of cellular structures in the skin with nanosecond pulsed electric fields

Background and Objectives

This study describes the effects of nanosecond pulsed electric fields (nsPEF) on the epidermis and dermis of normal skin scheduled for excision in a subsequent abdominoplasty. NsPEF therapy applies nanosecond pulses of electrical energy to induce regulated cell death (RCD) in cellular structures, with negligible thermal effects. Prior pre‐clinical studies using nsPEF technology have demonstrated the ability to stimulate a lasting immune response in animal tumor models, including melanoma. This first‐in‐human‐use of nsPEF treatment in a controlled study to evaluate the dose‐response effects on normal skin and subcutaneous structures is intended to establish a safe dose range of energies prior to use in clinical applications using nsPEF for non‐thermal tissue modification.

Study Design/Materials and Methods

Seven subjects with healthy tissue planned for abdominoplasty excision were enrolled. Five subjects were evaluated in a longitudinal, 60‐day study of effects with doses of six nsPEF energy levels. A total of 30 squares of spot sizes 25mm² or less within the planned excision area were treated and then evaluated at 1 day, 5 days, 15 days, 30 days, and 60 days prior to surgery. Photographs were taken over time of each treated area and assessed by three independent and blinded dermatologists for erythema, flaking and crusting using a 5‐point scale (0 = low, 4 = high). Punch biopsies of surgically removed tissue were processed and evaluated for tissue changes using hematoxylin and eosin, trichome, caspase‐3, microphthalmia transcription factor, and elastin stains and evaluated by a dermatopathologist. The skin of two subjects received additional treatments at 2 and 4 hours post‐nsPEF and was evaluated in a similar manner.

Results

Most energy settings exhibited delayed epidermal loss followed by re‐epithelization by day 15 and a normal course of healing. Histologic analysis identified the appearance of activated caspase‐3 at two and four hours after nsPEF treatment, but not at later time points. At the 1‐day time point, a nucleolysis effect was observed in epidermal cells, as evidenced by the lack of nuclear staining while the epidermal plasma membranes were still intact. Cellular structures within the treatment zone such as melanocytes, sebaceous glands, and hair follicles were damaged while acellular structures such as elastic fibers and collagen were largely unaffected except for TL6 which showed signs of dermal damage. Melanocytes reappeared at levels comparable with untreated controls within 1 month of nsPEF treatment.

Conclusions

The selective effect of nsPEF treatment on cellular structures in the epidermal and dermal layers suggests that this non‐thermal mechanism for targeting cellular structures does not affect the integrity of dermal tissue within a range of energy levels. The specificity of effects and a favorable healing response makes nsPEF ideal for treating cellular targets in the epidermal or dermal layers of the skin, including treatment of benign and malignant lesions. NsPEF skin treatments provide a promising, non‐thermal method for treating skin conditions and removing epidermal lesions. © 2019 The Authors. Lasers in Surgery and Medicine Published by Wiley Periodicals, Inc.

Nanosecond pulsed electric fields enhanced chondrogenic potential of mesenchymal stem cells via JNK/CREB-STAT3 signaling pathway

Background

Nanosecond pulsed electric fields (nsPEFs) can produce more significant biological effects than traditional electric fields and have thus attracted rising attention in developing medical applications based on short pulse duration and high field strength, such as effective cancer therapy. However, little is known about their effects on the differentiation of stem cells. Furthermore, mechanisms of electric fields on chondrogenic differentiation of mesenchymal stem cells (MSCs) remain elusive, and effects of electric fields on cartilage regeneration need to be verified in vivo. Here, we aimed to study the effects of nsPEFs on chondrogenic differentiation of MSCs in vitro and in vivo and further to explore the mechanisms behind the phenomenon.

Methods

The effects of nsPEF-preconditioning on chondrogenic differentiation of mesenchymal stem cells (MSCs) in vitro were evaluated using cell viability, gene expression, glycosaminoglycan (sGAG) content, and histological staining, as well as in vivo cartilage regeneration in osteochondral defects of rats. Signaling pathways were investigated with protein expression and gene expression, respectively.

Results

nsPEF-preconditioning with proper parameters (10 ns at 20 kV/cm, 100 ns at 10 kV/cm) significantly potentiated chondrogenic differentiation capacity of MSCs with upregulated cartilaginous gene expression and increased matrix deposition through activation of C-Jun NH2-terminal kinase (JNK) and cAMP-response element binding protein (CREB), followed by activation of downstream signal transducer and activator of transcription (STAT3). Implantation of nsPEF-preconditioned MSCs significantly enhanced cartilage regeneration in vivo, compared with implantation of non-nsPEF-preconditioned MSCs.

Conclusion

This study demonstrates a unique approach of nsPEF treatment to potentiate the chondrogenic ability of MSCs through activation of JNK/CREB-STAT3 that could have translational potential for MSC-based cartilage regeneration.

Electronic supplementary material

The online version of this article (10.1186/s13287-019-1133-0) contains supplementary material, which is available to authorized users.

Effect of nanosecond pulsed electric field treatment on cell proliferation of microalgae

Photoautotrophic microalgae based biorefinery concepts are currently not competitive compared to other established production systems. Therefore, innovative upstream processes need to be developed to increase the competitiveness of photoautotrophic microalgae biorefinery concepts. Abiotic sub-lethal stress induction via nanosecond pulsed electric field (nsPEF) treatment might be a viable process to increase the efficiency of photoautotrophic microalgae cultivation. In this work, an increased cell growth after nsPEF treatment was observable. Application of nsPEF to highly proliferating cells in a repetitive process resulted in a statistical significant increase in cell growth (p = 0.009). The effect was most pronounced after five days wherefore cellular structures and processes were analyzed to reveal a possible mechanism. Within this work, a protocol for increased cell proliferation with a possible mechanism was derived, which improves competitiveness of photoautotrophic microalgae biorefineries in the future. However, based on the derived mechanism, the results are also relevant for other microorganisms.