Electroporation-based Technologies Research Articles

Burst sine wave electroporation (B-SWE) for expansive blood-brain barrier disruption and controlled non-thermal tissue ablation for neurological disease.

The blood-brain barrier (BBB) limits the efficacy of treatments for malignant brain tumors, necessitating innovative approaches to breach the barrier. This study introduces burst sine wave electroporation (B-SWE) as a strategic modality for controlled BBB disruption without extensive tissue ablation and compares it against conventional pulsed square wave electroporation-based technologies such as high-frequency irreversible electroporation (H-FIRE). Using an in vivo rodent model, B-SWE and H-FIRE effects on BBB disruption, tissue ablation, and neuromuscular contractions are compared. Equivalent waveforms were designed for direct comparison between the two pulsing schemes, revealing that B-SWE induces larger BBB disruption volumes while minimizing tissue ablation. While B-SWE exhibited heightened neuromuscular contractions when compared to equivalent H-FIRE waveforms, an additional low-dose B-SWE group demonstrated that a reduced potential can achieve similar levels of BBB disruption while minimizing neuromuscular contractions. Repair kinetics indicated faster closure post B-SWE-induced BBB disruption when compared to equivalent H-FIRE protocols, emphasizing B-SWE's transient and controllable nature. Additionally, finite element modeling illustrated the potential for extensive BBB disruption while reducing ablation using B-SWE. B-SWE presents a promising avenue for tailored BBB disruption with minimal tissue ablation, offering a nuanced approach for glioblastoma treatment and beyond.

Tissue Nanotransfection Silicon Chip and Related Electroporation-Based Technologies for In Vivo Tissue Reprogramming.

Tissue nanotransfection (TNT), a cutting-edge technique of in vivo gene therapy, has gained substantial attention in various applications ranging from in vivo tissue reprogramming in regenerative medicine, and wound healing to cancer treatment. This technique harnesses the advancements in the semiconductor processes, facilitating the integration of conventional transdermal gene delivery methods-nanoelectroporation and microneedle technologies. TNT silicon chips have demonstrated considerable promise in reprogramming fibroblast cells of skin in vivo into vascular or neural cells in preclinical studies to assist in the recovery of injured limbs and damaged brain tissue. More recently, the application of TNT chips has been extended to the area of exosomes, which are vital for intracellular communication to track their functionality during the wound healing process. In this review, we provide an in-depth examination of the design, fabrication, and applications of TNT silicon chips, alongside a critical analysis of the electroporation-based gene transfer mechanisms. Additionally, the review discussed the existing limitations and challenges in the current technique, which may project future trajectories in the landscape of gene therapy. Through this exploration, the review aims to shed light on the prospects of TNT in the broader context of gene therapy and tissue regeneration.

Bioelectricity: A Multifaceted Discipline, and a Multifaceted Issue!

BioelectricityVol. 5, No. 2 EditorialFree AccessBioelectricity: A Multifaceted Discipline, and a Multifaceted Issue!Mustafa B.A. Djamgoz and Michael LevinMustafa B.A. DjamgozMustafa B.A. Djamgoz, PhD, Co-Editor-in-Chief E-mail Address: m.djamgoz@imperial.ac.ukhttps://orcid.org/0000-0003-1435-8540Imperial College London, London, United Kingdom.Search for more papers by this author and Michael LevinMichael Levin, PhD, Co-Editor-in-Chief E-mail Address: michael.levin@tufts.eduTufts University, Medford, Massachusetts, USA.Search for more papers by this authorPublished Online:16 Jun 2023https://doi.org/10.1089/bioe.2023.0022.editorialAboutSectionsPDF/EPUB Permissions & CitationsPermissionsDownload CitationsTrack CitationsAdd to favorites Back To Publication ShareShare onFacebookTwitterLinked InRedditEmail Dear bioelectricity communityIt has been a busy few months in the field. The publication of Sally Adee's book on “We Are Electric: The New Science of Our Body's Electrome” caused a significant stir in the international media. There is a review of the book in this issue, and even school kids have been asking “how can we learn more about bioelectricity?”! The publication of Adee's book coincided complementarily with our cracking special issue on “bioelectricity of plants” published in March (and continued in a special section here). This special issue highlighted among several topics the role of bioelectric interactions in the life-sustaining process of photosynthesis.The current issue contains articles emphasizing as ever the impact of electricity in a range of biological phenomena from bacteria and yeasts to human cancer. Yet, we would like to further broaden our coverage and attract more articles on medical, engineering, and industrial matters relating to bioelectricity. Our newly established formal association with the International Society for Electroporation-Based Technologies and Treatments (ISEBTT) has already brought out several exciting facets.One intriguing example is how electroporation of grape mash can enhance the polyphenol content of the juice (including wine) that may subsequently be made into a healthier product. We hope to cover several aspects and applications of “electroporation” in future special issues. We would also like to do justice to the rich bioelectricity of the immune system. In short, we would keenly welcome suggestions from potential guest editors to oversee special issue on such important topics. We are optimistic of the future with the COVID-19 pandemic officially over and research laboratories back to buzzing with activity.This month promises to be another landmark in the journal's 5-year history—any day now (if not already by the time you read this), we should be receiving our first impact factor (IF). Even then, however, we shall be taking this with a pinch of salt at a time when the relevance of journal IFs is recently being hotly debated, as these may be playing an indirect part in the ongoing plethora of article retractions! Needless to say, keeping up the quality and sustainability of Bioelectricity is the utmost priority of us as coeditor-in-chiefs and the editorial board as a whole.We wish you all a healthy and fruitful summer.FiguresReferencesRelatedDetails Volume 5Issue 2Jun 2023 InformationCopyright 2023, Mary Ann Liebert, Inc., publishersTo cite this article:Mustafa B.A. Djamgoz and Michael Levin.Bioelectricity: A Multifaceted Discipline, and a Multifaceted Issue!.Bioelectricity.Jun 2023.75-75.http://doi.org/10.1089/bioe.2023.0022.editorialPublished in Volume: 5 Issue 2: June 16, 2023PDF download

Research frontiers of electroporation-based applications in cancer treatment: a bibliometric analysis.

Electroporation, the breakdown of the biomembrane induced by external electric fields, has increasingly become a research hotspot for its promising related methods in various kinds of cancers. In this article, we utilized CiteSpace 6.1.R2 to perform a bibliometric analysis on the research foundation and frontier of electroporation-based applications in cancer therapy. A total of 3,966 bibliographic records were retrieved from the Web of Science Core Collection for the bibliometric analysis. Sersa G. and Mir L. M. are the most indispensable researchers in this field, and the University of Ljubljana of Slovenia is a prominent institution. By analyzing references and keywords, we found that, with a lower recurrence rate, fewer severe adverse events, and a higher success rate, irreversible electroporation, gene electrotransfer, and electrochemotherapy are the three main research directions that may influence the future treatment protocol of cancers. This article visualized relevant data to synthesize scientific research on electroporation-based cancer therapy, providing helpful suggestions for further investigations on electroporation. Although electroporation-based technologies have been proven as promising tools for cancer treatment, its radical mechanism is still opaque and their commercialization and universalization need further efforts from peers.

Recent Advancements in Electroporation Technologies: From Bench to Clinic.

Over the past decade, the increased adoption of electroporation-based technologies has led to an expansion of clinical research initiatives. Electroporation has been utilized in molecular biology for mammalian and bacterial transfection; for food sanitation; and in therapeutic settings to increase drug uptake, for gene therapy, and to eliminate cancerous tissues. We begin this article by discussing the biophysics required for understanding the concepts behind the cell permeation phenomenon that is electroporation. We then review nano- and microscale single-cell electroporation technologies before scaling up to emerging in vivo applications.

Histone deacetylase 4 and 5 translocation elicited by microsecond pulsed electric field exposure is mediated by kinase activity.

Electroporation-based technologies using microsecond pulsed electric field (µsPEF) exposures are established as laboratory and clinical tools that permeabilize cell membranes. We demonstrate a µsPEF bioeffect on nucleocytoplasmic import and export of enzymes that regulate genetic expression, histone deacetylases (HDAC) -4 and -5. Their μsPEF-induced nucleocytoplasmic transport depends on presence and absence of extracellular calcium ions (Ca2+) for both MCF7 and CHO-K1 cells. Exposure to 1, 10, 30 and 50 consecutive square wave pulses at 1Hz and of 100µs duration with 1.45kV/cm magnitude leads to translocation of endogenous HDAC4 and HDAC5. We posit that by eliciting a rise in intracellular Ca2+ concentration, a signaling pathway involving kinases, such as Ca2+/CaM-dependent protein kinase II (CaMKII), is activated. This cascade causes nuclear export and import of HDAC4 and HDAC5. The potential of µsPEF exposures to control nucleocytoplasmic transport unlocks future opportunities in epigenetic modification.

To Close or to Collapse: The Role of Charges on Membrane Stability upon Pore Formation.

Resealing of membrane pores is crucial for cell survival. Membrane surface charge and medium composition are studied as defining regulators of membrane stability. Pores are generated by electric field or detergents. Giant vesicles composed of zwitterionic and negatively charged lipids mixed at varying ratios are subjected to a strong electric pulse. Interestingly, charged vesicles appear prone to catastrophic collapse transforming them into tubular structures. The spectrum of destabilization responses includes the generation of long‐living submicroscopic pores and partial vesicle bursting. The origin of these phenomena is related to the membrane edge tension, which governs pore closure. This edge tension significantly decreases as a function of the fraction of charged lipids. Destabilization of charged vesicles upon pore formation is universal—it is also observed with other poration stimuli. Disruption propensity is enhanced for membranes made of lipids with higher degree of unsaturation. It can be reversed by screening membrane charge in the presence of calcium ions. The observed findings in light of theories of stability and curvature generation are interpreted and mechanisms acting in cells to prevent total membrane collapse upon poration are discussed. Enhanced membrane stability is crucial for the success of electroporation‐based technologies for cancer treatment and gene transfer.

Abstract 334: Creation and analysis of advanced in vitro cancer models in the real architecture for 3D tissue (RAFT™) culture system

Abstract Conventional in vitro assays are based on cells grown on two-dimensional (2D) substrates, which are not representative of the true in vivo cell environment. In tissue environments, cells interact with neighboring cells and the extracellular matrix (ECM). Three-dimensional (3D) cell culture methods allow cells to grow in structures more resembling the in vivo environment. The RAFT™ 3D Culture System uses a collagen matrix at physiologically relevant concentrations. In the presented applications, cells from the colon cancer line HCT 116 and neutralized collagen are mixed and subsequently incubated at 37°C to allow the formation of a cell-seeded hydrogel. Specialized RAFT™ Absorbers are placed on top of the hydrogels. Those absorbers gently remove abundant medium, thus compacting the cell/collagen hydrogel prior futher culture. Additional cell types like fibroblasts, endothelial or epithelial cells may be added to allow the creation of more complex models. While 3D cultures more closely mimic the in vivo cell environment, it is often difficult to apply transient transfection methods to these dense, tissue-like structures. Here we give a guideline how to use the electroporation-based Nucleofector™ Technology for creating transiently transfected cells for further culture in the RAFT™ System. HCT 116 was harvested and transfected with pmaxGFP™ Vector in suspension using the 4D Nucleofector™ System X-Unit. Subsequently, cells were embedded in RAFT™ Cultures. Overall transfection efficiencies and cell viabilities were comparable between RAFT™ 3D Cultures and standard 2D cultures. Transfection efficiencies of more than 90% were observed in both formats. GFP expression was still detectable 4 days after transfection. Innovative gene-editing tools like CRISPR-Cas nuclease-based systems could be used to obtain more long-term transgene expression. Another challenge is the analysis of cells in dense, tissue-like structures compared to 2D monolayer culture. HCT 116 cells formed compact aggregate-like structures in RAFT™ 3D Cultures that resembled small tumors in vivo. Therefore, we developed a protocol for immunocytochemistry that allows effective antibody staining of HCT 116 containing RAFT™ Cultures. In addition, we will explain how to measure cell viability in RAFT™ Cultures with the ViaLight™ Plus Cell Proliferation and Cytotoxicity BioAssay. The ViaLight™ Assay is based on the bioluminescent detection of cellular ATP as a measure of cell viability. Only minor modifications of the standard 2D cell culture protocol are required for using the assay for RAFT™ Cultures. By elongating the lysis step of the Vialight™ Assay from 10 minutes to 30 minutes, a similar performance of the assay was observed for HCT 116 containing 2D and RAFT™ Cultures. In summary, we show how easily genetically modified in vitro 3D cancer models can be generated in the RAFT™ 3D Cell Culture System and how such models can be analyzed using standard methods like immunocytochemistry and the ViaLight™ Viability Assay. Citation Format: Sabine Schaepermeier, Theresa D'Souza, Aurita Menezes, Claudia Schwartz, Jenny Schroeder. Creation and analysis of advanced in vitro cancer models in the real architecture for 3D tissue (RAFT™) culture system [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 334.

High-Voltage Electrical Pulses in Oncology: Irreversible Electroporation, Electrochemotherapy, Gene Electrotransfer, Electrofusion, and Electroimmunotherapy.

This review summarizes the use of high-voltage electrical pulses (HVEPs) in clinical oncology to treat solid tumors with irreversible electroporation (IRE) and electrochemotherapy (ECT). HVEPs increase the membrane permeability of cells, a phenomenon known as electroporation. Unlike alternative ablative therapies, electroporation does not affect the structural integrity of surrounding tissue, thereby enabling tumors in the vicinity of vital structures to be treated. IRE uses HVEPs to cause cell death by inducing membrane disruption, and it is primarily used as a radical ablative therapy in the treatment of soft-tissue tumors in the liver, kidney, prostate, and pancreas. ECT uses HVEPs to transiently increase membrane permeability, enhancing cellular cytotoxic drug uptake in tumors. IRE and ECT show immunogenic effects that could be augmented when combined with immunomodulatory drugs, a combination therapy the authors term electroimmunotherapy. Additional electroporation-based technologies that may reach clinical importance, such as gene electrotransfer, electrofusion, and electroimmunotherapy, are concisely reviewed. HVEPs represent a substantial advancement in cancer research, and continued improvement and implementation of these presented technologies will require close collaboration between engineers, interventional radiologists, medical oncologists, and immuno-oncologists.

Achieving therapeutic efficacy with a high performance, electroporation-based cellular engineering technology

Background & Aim Advances in cell-based therapies for treating cancer and other diseases have created a demand for rapid and flexible manufacturing processes. While virus-based delivery methods have provided the foundation for the cell therapy revolution, the costs of manufacturing viral vectors and related safety issues have created an urgent need for non-viral approaches to cellular engineering that can be implemented at scale in a GMP environment. In this poster, we present data on a GMP-compliant, scalable electroporation-based technology for engineering primary human cells, stem cells and cell lines with high efficiency while maintaining high cell viability. Methods, Results & Conclusion Examples include introducing precise genomic modifications into primary T cells and hematopoietic stem cells via transfection of mRNA and RNPs encoding zinc finger nucleases and CRISPR/Cas9 components as well as single nucleotide editing for correction of disease causing genetic mutations including X-linked chronic granulomatous disease (X-CGD) and sickle cell disease (SCD). We also include data on redirecting the specificity of T cells and NK cells by expressing recombinant receptors. Finally, we provide examples of cellular engineering with induced pluripotent stem cells (iPSCs) and other types of progenitor cells.

Transport of charged small molecules after electropermeabilization \u2014 drift and diffusion

BackgroundApplications of electric-field-induced permeabilization of cells range from cancer therapy to wastewater treatment. A unified understanding of the underlying mechanisms of membrane electropermeabilization, however, has not been achieved. Protocols are empirical, and models are descriptive rather than predictive, which hampers the optimization and expansion of electroporation-based technologies. A common feature of existing models is the assumption that the permeabilized membrane is passive, and that transport through it is entirely diffusive. To demonstrate the necessity to go beyond that assumption, we present here a quantitative analysis of the post-permeabilization transport of three small molecules commonly used in electroporation research — YO-PRO-1, propidium, and calcein — after exposure of cells to minimally perturbing, 6 ns electric pulses.ResultsInflux of YO-PRO-1 from the external medium into the cell exceeds that of propidium, consistent with many published studies. Both are much greater than the influx of calcein. In contrast, the normalized molar efflux of calcein from pre-loaded cells into the medium after electropermeabilization is roughly equivalent to the influx of YO-PRO-1 and propidium. These relative transport rates are correlated not with molecular size or cross-section, but rather with molecular charge polarity.ConclusionsThis comparison of the kinetics of molecular transport of three small, charged molecules across electropermeabilized cell membranes reveals a component of the mechanism of electroporation that is customarily taken into account only for the time during electric pulse delivery. The large differences between the influx rates of propidium and YO-PRO-1 (cations) and calcein (anion), and between the influx and efflux of calcein, suggest a significant role for the post-pulse transmembrane potential in the migration of ions and charged small molecules across permeabilized cell membranes, which has been largely neglected in models of electroporation.

Education on electrical phenomena involved in electroporation-based therapies and treatments: a blended learning approach.

BackgroundElectroporation-based applications require multidisciplinary expertise and collaboration of experts with different professional backgrounds in engineering and science. Beginning in 2003, an international scientific workshop and postgraduate course electroporation based technologies and treatments (EBTT) has been organized at the University of Ljubljana to facilitate transfer of knowledge from leading experts to researches, students and newcomers in the field of electroporation. In this paper we present one of the integral parts of EBTT: an e-learning practical work we developed to complement delivery of knowledge via lectures and laboratory work, thus providing a blended learning approach on electrical phenomena involved in electroporation-based therapies and treatments.MethodsThe learning effect was assessed via a pre- and post e-learning examination test composed of 10 multiple choice questions (i.e. items). The e-learning practical work session and both of the e-learning examination tests were carried out after the live EBTT lectures and other laboratory work. Statistical analysis was performed to compare and evaluate the learning effect measured in two groups of students: (1) electrical engineers and (2) natural scientists (i.e. medical doctors, biologists and chemists) undergoing the e-learning practical work in 2011–2014 academic years. Item analysis was performed to assess the difficulty of each item of the examination test.ResultsThe results of our study show that the total score on the post examination test significantly improved and the item difficulty in both experimental groups decreased. The natural scientists reached the same level of knowledge (no statistical difference in total post-examination test score) on the post-course test take, as do electrical engineers, although the engineers started with statistically higher total pre-test examination score, as expected.ConclusionsThe main objective of this study was to investigate whether the educational content the e-learning practical work presented to the students with different professional backgrounds enhanced their knowledge acquired via lectures during EBTT. We compared the learning effect assessed in two experimental groups undergoing the e-learning practical work: electrical engineers and natural scientists. The same level of knowledge on the post-course examination was reached in both groups. The results indicate that our e-learning platform supported by blended learning approach provides an effective learning tool for populations with mixed professional backgrounds and thus plays an important role in bridging the gap between scientific domains involved in electroporation-based technologies and treatments.Electronic supplementary materialThe online version of this article (doi:10.1186/s12938-016-0152-7) contains supplementary material, which is available to authorized users.

Food Science without Borders.

Food Science without Borders.

Applications of pulsed electric field for food processing — Special issue

A wide variety of applications of pulsed electric field (PEF) that are based on cell membrane electroporation have been developed. In the food area these are focused on nonthermal microbial inactivation for food pasteurization, treatment of vegetable, animal and microbial cells to enhance the efficiency of mass transfer of water and other valuable compounds, in drying, extraction and infusion processes. Over past decades, much research on basic and applied aspects of PEF for the food industry has been carried out contributing to a better understanding of this innovative food processing technology. The lack of reliable and viable industrial equipment limited the exploitation of PEF in the food industry for several years. However recent developments in pulse power generators have permitted the design of appropriate PEF equipment at an industrial scale. First commercial applications of PEF technology have been achieved and it is expected that new ones will be launched in the near future. Thisspecialissueonthe useof pulsedelectric fields for foodprocessing contains manuscripts on recent developments in the field of PEF prepared by participants of the first edition of the “Training School on Applications of Pulsed Electric Fields (PEF) for Food Processing” that was held at the University of Zaragoza (Spain) in January 20–23 of 2004. The School was organized in the framework of the COST TD1104 Action — European network for development of electroporation-based technologies and treatments (www.electroporation.net) and joined for four days, 13 lectures and 33 students coming from 15 countries of four different continents belonging to both academia and industry. The aim of the School was to offer an overview of knowledge and understanding of the basic principles involved in food processing by PEF and to provide practical demonstrations in the use of PEF for liquid food pasteurization and improving mass transfer operations in the food

Electroporation-based technologies for medicine: principles, applications, and challenges.

When high-amplitude, short-duration pulsed electric fields are applied to cells and tissues, the permeability of the cell membranes and tissue is increased. This increase in permeability is currently explained by the temporary appearance of aqueous pores within the cell membrane, a phenomenon termed electroporation. During the past four decades, advances in fundamental and experimental electroporation research have allowed for the translation of electroporation-based technologies to the clinic. In this review, we describe the theory and current applications of electroporation in medicine and then discuss current challenges in electroporation research and barriers to a more extensive spread of these clinical applications.

Introduction to Third Special Electroporation-Based Technologies and Treatments Issue

We are pleased to introduce this third special electroporation-based technologies and treatments issue of the Journal of Membrane Biology. Readers will find here reports of recent developments in the field of electroporation that were presented and discussed during the 6th International Workshop and Postgraduate Course on ‘‘Electroporation-Based Technologies and Treatments’’ (EBTT 2012) held in Ljubljana, November 18–24, 2012. Participants included seven faculty members, eight lecturers who are recognized researchers in the field, 17 young scientists and clinicians, and 32 students—altogether 64 participants coming from 13 different countries. Once again colleagues from the Laboratory of Biocybernetics of the Faculty of Electrical Engineering at the University of Ljubljana conducted practical training exercises during the afternoons—a unique opportunity for hands-on experience guided by experts. This school is now an established platform for learning, extending, and consolidating knowledge of electroporation mechanisms and applications. The field of cell and membrane electroporation—theoretical studies, laboratory experiments, and clinical and industrial applications—continues to grow and expand. Electroporation is now performed in silico (molecular dynamics and numerical simulations), with artificial membrane systems, in cultured cells, in animal and plant tissues, and in whole organisms. The importance of electroporation, in research and in biotechnological, medical, and industrial applications, was recognized in 2012 when 22 countries signed a Memorandum of Understanding to participate in a COST action at the European level (COST TD 1104 ‘‘European network for development of electroporation-based technologies and treatments’’) (Miklavcic 2012). In the year that has passed since launching, this EU Action (http://www.electroporation.net/) has gathered 445 participants from 150 institutions in 32 countries, with the EBTT meeting as one of its many activities. The peer-reviewed selection of articles presented in this dedicated issue offers a wide-ranging view of the various aspects of current research in the field of cell electroporation. We wish to thank all the contributors for their efforts in presenting their recent results to the journal’s readers who, whether new or old in the field, will find new data and interesting ideas in this special issue. We would especially like to express our sincere thanks to our scientific colleagues, to the reviewers, to the agencies sponsoring our research, in particular to the Slovenian Research Agency and the Centre National de la Recherche Scientifique (CNRS), and to the Bioelectrochemical Society which has sponsored the school from its very beginning. We also would like to thank BIA Separations (Slovenia), Bio-Rad Laboratories (USA), C3M (Slovenia), IGEA (Italy), Iskra Medical (Slovenia), Kemomed (Slovenia), Mediline (Slovenia) and Profector (Ireland), whose financial support allowed us to assist many D. Miklavcic Faculty of Electrical Engineering, University of Ljubljana, Tržaska 25, 1000 Ljubljana, Slovenia e-mail: damijan.miklavcic@fe.uni-lj.si

Network for development of electroporation-based technologies and treatments: COST TD1104.

Exposure of biological cells to a sufficiently strong external electric field results in increased permeability of cell membranes, referred to as “electroporation.” Since all types of cells (animal, plant and microorganism) can be effectively electroporated, electroporation is considered to be a universal method and a platform technology. Electroporation has become a widely used technology applicable to, e.g., cancer treatment, gene transfection, food and biomass processing and microbial inactivation. However, despite significant progress in electroporation-based applications, there is a lack of coordination and interdisciplinary exchange of knowledge between researchers from different scientific domains. Thus, critical mass for new major breakthroughs is missing. This is why we decided to establish cooperation between research groups working in different fields of electroporation. Cooperation in Science and Technology (COST), which funds networking and capacity-building activities, presents a perfect framework for such scientific cooperation. This COST action aims at (1) providing necessary steps toward EU cooperation of science and technology to foster basic understanding of electroporation; (2) improving communication between research groups, resulting in streamlining European research and development activities; and (3) enabling development of new and further development of existing electroporation-based applications by integrating multidisciplinary research teams, as well as providing comprehensive training for early-stage researchers. Results of this COST action will provide multiple societal, scientific and technological benefits from improving existing electroporation-based applications to adding new ones in the fields of medicine, biotechnology and environmental preservation.

Nucleofection of a DNA vaccine into human monocyte-derived dendritic cells

An efficient method for delivering DNA vaccines into dendritic cells is considered to be of paramount importance. Electroporation-based technology (nucleofection) has gained increasingly popularity, but few reports focused on the possible functional consequences related to this method. In this study, the nucleofection technique was used to transfer the recombinant plasmid into hMoDCs for phenotype expression analysis and immunopotency detection. The results showed that the nucleofection of increasing concentrations of plasmid DNA decreased the viability of the hMoDCs. The welfare of nucleofected hMoDCs depended on the dosage of the plasmid and the plasmid’s retention time within the cells. Accompanied by the process of nucleofection, it would bring some non-specific changes. The methodology reported here is suggestive of a feasible system for DNA vaccine transfer into hMoDCs with the caution of certain undesired effect.

Electroporation-Based Technologies and Treatments

When a cell is exposed to a sufficiently large electric field, even for a very short time, its plasma membrane is changed so that molecules that normally cross the membrane only in minute amounts can more readily pass through the barrier. This phenomenon was first described by Neumann and Rosenheck (1972) in this journal. A decade later gene transfer was achieved by means of electroporation (Neumann et al. 1982). This technique is now widely used in laboratories around the world and is gaining even more attention in recent years as a method for introducing foreign genes into cells in vivo (Mir 2009), with good prospects for use in a clinical setting (Daud et al. 2008). Electroporation has been used in the last decade also for improving cancer drug delivery to cells. Preclinical investigations in the late 1980s (Orlowski et al. 1988; Mir et al. 1991) were followed by the first clinical trial in 1991 (Mir et al. 1991; Belehradek et al. 1993). Electrochemotherapy as an effective and safe local treatment for cutaneous and subcutaneous tumors (Marty et al. 2006; Sersa and Miklavcic 2008) is now accepted in a number of countries, is routinely employed in more than 60 cancer treatment centers and is being further developed for treating more deep-seated tumors (Miklavcic et al. 2010). Electroporation can be used in all kinds of isolated cells as well as in tissues. The electric field to which one exposes the target cell has to be of sufficient strength and the exposure of sufficient duration. The magnitude of the electric field to be used depends on cell type, size, orientation and density; pulse duration; and number of pulses. The selection of pulse parameters is influenced also by the size and type of molecule to be internalized. Depending on the location and size of the targeted tissue, electric pulses will be delivered via appropriate electrodes chosen among a number of different types. Geometry and positioning of electrodes affect electric field distribution, which is important for effective in vivo electropermeabilization (Miklavcic et al. 1998, 2000). Strategies for the treatment of malignancies based on direct effects of pulsed electric fields on cells, independent of the induced influx of pharmacological or genetic material, are also under development. These include tumor ablation by irreversible electroporation (Al-Sakere et al. 2007) and by the application of intense (MV/m), nanosecond-duration pulses, which induce apoptosis and destruction of the tumor vascularization (Nuccitelli et al. 2006). This special issue of the Journal of Membrane Biology features selected peer-reviewed reports from investigators currently active in electroporation-related research who attended the Fourth International Scientific Workshop and Postgraduate Course on Electroporation-Based Technologies and Treatments in Ljubljana, Slovenia, in November 2009. This unique working conference at the University of Ljubljana has been organized every 2 years since the first one in 2003. More than 200 participants from 21 countries D. Miklavcic Faculty of Electrical Engineering, University of Ljubljana, Tržaska 25, 1000 Ljubljana, Slovenia e-mail: damijan.miklavcic@fe.uni-lj.si