Transient electropermeabilization of cells in culture. Increase of the cytotoxicity of anticancer drugs

Preclinical evaluation of reversible pulsed electrical field: electrophysiological and histological assessment of myocardium

Background

Pulsed field ablation, as a non-thermal ablation modality, has received increasing attention. The aim of this study is to explore whether a reversible pulsed electric field (RPEF) can temporarily inhibit electrical conduction and provide a novel method for precise ablation of arrhythmia.

Methods

RPEF energy was delivered from an ablation catheter to the atrium of six dogs, followed by a series of electrogram and histology assessments.

Results

RPEF ablation of ordinary myocardium resulted in an average reduction of 68.3% (range, 53.7%-83.8%) in electrogram amplitude, while 5 min later, the amplitude in eight electrograms returned to 77.9% (range, 72.4%-87.3%) of baseline. Similarly, the amplitude of the sinoatrial node electrograms reduced by an average of 73.0% (range, 60.2%-84.4%) after RPEF ablation, but recovered to 84.9% (range, 80.3%-88.5%) of baseline by 5 min. No necrotic change was detected in histopathology. Transient third-degree atrioventricular block occurred following the ablation of the maximum His potential sites with RPEF, the duration of which was voltage dependent. The histopathological results showed necrosis of the myocardium at the ablation sites but no injury to His bundle cells.

Conclusions

RPEF can be applied to transiently block electrical conduction in myocardial tissues contributing to precise ablation.

The comparison of the dynamics of Ca2+ and bleomycin intracellular delivery after cell sonoporation and electroporation in vitro

Ca2+, in combination with SP or EP, induces cell cytotoxicity much faster compared to BLM. The application of BLM in combination with, SP or EP, reaches the level of cell death, induced by similar combination with Ca2+, only after 72 h. The methods of SP and EP were calibrated according to the level of differential cytotoxicity, determined after 6 days (using cell clonogenic assay). The combination of Ca2+ SP induces cell death faster than Ca2+ EP - after Ca2+ SP it increases to a maximum level after 15 min and remains constant for up to 6 days, while the cytotoxic efficiency after Ca2+ EP increases to the level of Ca2+ SP only after 72 h. The combination of BLM SP shows a very similar dynamics to BLM EP - both reach maximal level of cytotoxicity after 48-72 h. Ca2+ and BLM in combination with SP have shown similar levels of cytotoxicity at higher acoustic pressures (≥250 kPa); therefore, Ca2+ SP can be used to induce immediate and maximal level of cytotoxic effect. The faster cytotoxic efficiency of Ca2+ in combination with SP than EP was determined to be due to the involvement of microbubble inertial cavitation.

Electrochemotherapy in dogs and cats-A review

Electrochemotherapy (ECT) is a treatment modality that combines the electroporation of cell membranes with chemotherapy to facilitate the transport of non-permeant molecules into cells. Several canine and feline studies have shown promising results, suggesting that ECT can be a valid adjuvant or alternative treatment option for some tumours. The objective of this paper is to provide a bibliographic review of the principles and applications of ECT in veterinary medicine and to compare to its use in human medicine.

The equivalence of different types of electric pulses for electrochemotherapy with cisplatin - an in vitro study

BACKGROUND

Electrochemotherapy (ECT) is a treatment involving the administration of chemotherapeutics drugs followed by the application of 8 square monopolar pulses of 100 μs duration at a repetition frequency of 1 Hz or 5000 Hz. However, there is increasing interest in using alternative types of pulses for ECT. The use of high-frequency short bipolar pulses has been shown to mitigate pain and muscle contractions. Conversely, the use of millisecond pulses is interesting when combining ECT with gene electrotransfer for the uptake of DNA-encoding proteins that stimulate the immune response with the aim of converting ECT from a local to systemic treatment. Therefore, the aim of this study was to investigate how alternative types of pulses affect the efficiency of the ECT.

MATERIALS AND METHODS

We performed in vitro experiments, exposing Chinese hamster ovary (CHO) cells to conventional ECT pulses, high-frequency bipolar pulses, and millisecond pulses in the presence of different concentrations of cisplatin. We determined cisplatin uptake by inductively coupled plasma mass spectrometry and cisplatin cytotoxicity by the clonogenic assay.

RESULTS

We observed that the three tested types of pulses potentiate the uptake and cytotoxicity of cisplatin in an equivalent manner, provided that the electric field is properly adjusted for each pulse type. Furthermore, we quantified that the number of cisplatin molecules, resulting in the eradication of most cells, was 2-7 × 107 per cell.

CONCLUSIONS

High-frequency bipolar pulses and millisecond pulses can potentially be used in ECT to reduce pain and muscle contraction and increase the effect of the immune response in combination with gene electrotransfer, respectively.

Calcium Electroporation versus Electrochemotherapy with Bleomycin in an In Vivo CAM-Based Uveal Melanoma Xenograft Model

Despite recent advancements in the diagnosis and treatment of uveal melanoma (UM), its metastatic rate remains high and is accompanied by a highly dismal prognosis, constituting an unmet need for the development of novel adjuvant therapeutic strategies. We established an in vivo chick chorioallantoic membrane (CAM)-based UM xenograft model from UPMD2 and UPMM3 cell lines to examine its feasibility for the improvement of selection of drug candidates. The efficacy of calcium electroporation (CaEP) with 5 or 10 mM calcium chloride (Ca) and electrochemotherapy (ECT) with 1 or 2.5 µg/mL bleomycin in comparison to monotherapy with the tested drug or electroporation (EP) alone was investigated on the generated UM tumors. CaEP and ECT showed a similar reduction of proliferation and melanocytic expansion with a dose-dependent effect for bleomycin, whereas CaEP induced a significant increase of the apoptosis and a reduction of vascularization with varying sensitivity for the two xenograft types. Our in vivo results suggest that CaEP and ECT may facilitate the adequate local tumor control and contribute to the preservation of the bulbus, potentially opening new horizons in the adjuvant treatment of advanced UM.

Irreversible electroporation as a focal therapy for localized prostate cancer: A systematic review

Introduction

Irreversible electroporation (IRE) is a new and promising focal therapy for the treatment of localized prostate cancer. In this systematic review, we summarize the literature on IRE for prostate cancer published over the last decade.

Methods

PubMed and EMBASE were searched with the end date of May 2023 to find relevant publications on prostate cancer ablation using IRE. Original studies with focal IRE as the primary curative treatment which reported on functional or oncological outcomes were included. The bibliography of relevant studies was also scanned to identify suitable articles.

Results

A total of 14 studies reporting on 899 patients treated with IRE for localized prostate cancer were included. Of all the studies reviewed, 77% reported on recurrence within the zone of ablation, and it ranged from 0% to 38.9% for in-field and 3.6% to 28% for out-of-field recurrence. Although, a standardised follow-up protocol was not followed, all the studies employed serial prostate-specific antigen monitoring, a multiparametric magnetic resonance imaging, and a biopsy (6-12 months post-treatment). Across all the studies, 58% reported that the urinary continence returned to the pretreatment levels and 25% reported a minor decrease in the continence from the baseline at 12-months of follow-up. Erections sufficient for intercourse varied from 44% to 75% at the baseline to 55% to 100% at 12-months of follow-up across all the studies.

Conclusion

IRE, as a focal therapy, shows promising results with minimal complications and reasonably effective oncological control, but the data comparing it to the standard of care is still lacking. Future research should focus on randomized definitive comparisons between IRE, radical prostatectomy, and radiation therapy.

Non-Thermal Liver Ablation: Existing and New Technology

Cancer has and continues to be a complex health crisis plaguing millions around the world. Alcohol ablation was one of the initial methods used for the treatment of liver lesions. It was surpassed by thermal ablation which has played a big role in the therapeutic arsenal for primary and metastatic liver tumors. However, thermal ablation has several shortcomings and limitations that prompted the development of alternative technologies including electroporation and histotripsy. Percutaneous alcohol injection in the liver lesion leads to dehydration and coagulative necrosis. This technology is limited to the lesion with relative sparing of the surrounding tissue, making it safe to use adjacent to sensitive structures. Electroporation utilizes short high-voltage pulses to permeabilize the cell membrane and can result in cell death dependent on the threshold reached. It can effectively target the tumor margins and has lower damage rates to surrounding structures due to the short pulse duration. Histotripsy is a novel technology, and although the first human trial was just completed, its results are encouraging, given the sharp demarcation of the targeted tissue, lack of thermal damage, and potential for immunomodulation of the tumor microenvironment. Herein, we discuss these techniques, their uses, and overall clinical benefit.

Evaluation of the safety and feasibility of electrochemotherapy with intravenous bleomycin as local treatment of bladder cancer in dogs

Local treatment of canine urothelial carcinoma (UC) of the bladder is a challenge. More than 90% of the cases invade the muscular layer, more than 50% develop on bladder sites with a difficult surgical approach and often requiring radical surgical procedures. This study aims to evaluate the safety and feasibility of electrochemotherapy (ECT) with intravenous bleomycin (BLM) as a local therapy for bladder UC. This prospective study included 21 dogs with spontaneous bladder UC. Regional/distant metastases and neoplastic infiltration of the serosa was considered the main exclusion criteria. We had no deaths during ECT or in the immediate postoperative period, and no suture dehiscence. Most dogs (19/21) developed mild adverse effects, whereas two dogs developed ureteral stenosis. Complete response (CR) was achieved in 62% of the cases (13/21), while partial response (PR) was achieved in 24% (5/21). The median survival and disease-free survival times were 284 and 270 days, respectively. Overall survival was significantly better in the dogs who achieved a CR. In conclusion, ECT was well-tolerated in dogs with UC, demonstrating its safety and feasibility. These data pave the way for new studies aimed at evaluating the effectiveness of ECT in canine bladder UC as a translational model for human disease.

Combination of Electrochemotherapy with Radiotherapy: A Comprehensive, Systematic, PRISMA-Compliant Review of Efficacy and Potential Radiosensitizing Effects in Tumor Control

Radiotherapy (RT) and electrochemotherapy (ECT) are established local treatments for cancer. While effective, both therapies have limitations, especially in treating bulky and poorly oxygenated tumors. ECT has emerged as a promising palliative treatment, raising interest in exploring its combination with RT to enhance tumor response. However, the potential benefits and challenges of combining these treatments remain unclear. A systematic review was conducted following PRISMA guidelines. PubMed, Scopus, and Cochrane libraries were searched. Studies were screened and selected based on predefined inclusion and exclusion criteria. Ten studies were included, comprising in vitro and in vivo experiments. Different tumor types were treated with ECT alone or in combination with RT. ECT plus RT demonstrated superior tumor response compared to that under single therapies or other combinations, regardless of the cytotoxic agent and RT dose. However, no study demonstrated a clear superadditive effect in cell survival curves, suggesting inconclusive evidence of specific ECT-induced radiosensitization. Toxicity data were limited. In conclusion, the combination of ECT and RT consistently improved tumor response compared to that with individual therapies, supporting the potential benefit of their combination. However, evidence for a specific ECT-induced radiosensitization effect is currently lacking. Additional investigations are necessary to elucidate the potential benefits of this combination therapy.

Effective proliferation control of MCF7 breast cancer using microsecond duration electrical pulse

BACKGROUND

Electro-permeablization using a pulse generator is a novel non-invasive approach for cancer therapy. It serves as a cell permeability enhancing agent for cancer treatment.

OBJECTIVE

In this article in vitro investigation of the effect of 1.0 kV/cm, 1.5 kV/cm and 2.0 kV/cm, 50 µs duration pulsed electric field on MCF-7 cell line has been done. Furthermore, combinational therapy of curcumin and electrical pulses has been also investigated.

MATERIAL AND METHOD

A variable voltage (100 V-1200 V, 100 V step) and 50 µs duration pulse generator has been designed, which is further used for the investigation of electroporation and destructive electrical field intensity. Investigation of the effect of electrical pulses on cancer cells has been performed using Trypan Blue Exclusion Test, MTT Assay and Clonogenic Assay.

RESULTS

It has been observed that electrical field intensity of 2 kV/cm, 50 µsec duration, 10 pulses at repetition rate of 1 pulse per second corresponding to total energy of 4 J is more than enough for causing necrotic cell death due to permanent damage of cell membrane of the cancer cell. Also, it has been observed that electrical pulse application enhances curcumin uptake by cells.

CONCLUSION

Electrical pulses can effectively inhibit the cancer cell growth and proliferation. Furthermore, observation shows that electroporation enhances the curcumin uptake, therefore, it can be used for therapeutic purposes.

Selection of Natural Compounds with HMGA-Interfering Activities and Cancer Cell Cytotoxicity

HMGA proteins are intrinsically disordered (ID) chromatin architectural factors characterized by three DNA binding domains (AT-hooks) that allow them to bind into the DNA minor groove of AT-rich stretches. HMGA are functionally involved in regulating transcription, RNA processing, DNA repair, and chromatin remodeling and dynamics. These proteins are highly expressed and play essential functions during embryonic development. They are almost undetectable in adult tissues but are re-expressed at high levels in all cancers where they are involved in neoplastic transformation and cancer progression. We focused on identifying new small molecules capable of binding into the minor groove of AT-rich DNA sequences that could compete with HMGA for DNA binding and, thus, potentially interfere with their activities. Here, a docking-based virtual screening of a unique high diversity in-house library composed of around 1000 individual natural products identified 16 natural compounds as potential minor groove binders that could inhibit the interaction between HMGA and DNA. To verify the ability of these selected compounds to compete with HMGA proteins, we screened them using electrophoretic mobility shift assays. We identified Sorocein C, a Diels-Alder (D-A)-type adducts, isolated from Sorocea ilicifolia and Sorocea bonplandii with an HMGA/DNA-displacing activity and compared its activity with that of two structurally related compounds, Sorocein A and Sorocein B. All these compounds showed a cytotoxicity effect on cancer cells, suggesting that the Sorocein-structural family may provide new and yet unexplored chemotypes for the development of minor groove binders to be evaluated as anticancer agents.

High-Frequency Electroporation and Chemotherapy for the Treatment of Cutaneous Malignancies: Evaluation of Early Clinical Response

High-frequency electroporation (HF-EP) with chemotherapy is a novel therapy proposed for both curative and palliative treatment of cutaneous malignancies. The use of high-frequency biphasic pulses is thought to reduce the painful muscle contractions associated with traditional electrochemotherapy (ECT), allowing treatment administration under local anaesthesia. This proof-of-concept study investigated the efficacy and tolerability of HF-EP protocols on a variety of cutaneous malignancies. A total of 97 lesions of five different histological subtypes were treated across 25 patients. At 12 weeks post-treatment, a 91.3% overall lesion response rate was observed (complete response: 79%; partial response: 12.3%), with excellent intraprocedural patient tolerability under local anaesthetic. HF-EP with chemotherapy shows promising results regarding tumour response rates for cutaneous malignancies of varying histological subtypes when compared to traditional ECT protocols. Improved patient tolerability is important, increasing the possibility of treatment delivery under local anaesthesia and potentially broadening the treatment envelope for patients with cutaneous malignancies.

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.

Electrochemotherapy Plus IL-2+IL-12 Gene Electrotransfer in Spontaneous Inoperable Stage III-IV Canine Oral Malignant Melanoma

Electrochemotherapy (ECT) is a standard of care in veterinary and human oncology. The treatment induces a well-characterized local immune response which is not able to induce a systemic response. In this retrospective cohort study, we evaluated the addition of gene electrotransfer (GET) of canine IL-2 peritumorally and IL-12 intramuscularly to enhance the immune response. Thirty canine patients with inoperable oral malignant melanoma were included. Ten patients received ECT+GET as the treatment group, while twenty patients received ECT as the control group. Intravenous bleomycin for the ECT was used in both groups. All patients had compromised lymph nodes which were surgically removed. Plasma levels of interleukins, local response rate, overall survival, and progression-free survival were evaluated. The results show that IL-2 and IL-12 expression peaked around days 7-14 after transfection. Both groups showed similar local response rates and overall survival times. However, progression-free survival resulted significantly better in the ECT+GET group, which is a better indicator than overall survival, as it is not influenced by the criterion used for performing euthanasia. We can conclude that the combination of ECT+GET using IL-2 and IL-12 improves treatment outcomes by slowing down tumoral progression in stage III-IV inoperable canine oral malignant melanoma.

The Assessment of Calcium and Bleomycin Cytotoxic Efficiency in Relation to Cavitation Dosimetry

Microbubble (MB)- and ultrasound (US)-facilitated intracellular Ca²⁺ delivery, known as sonoporation (SP), is a promising anticancer treatment modality, since it allows a spatio-temporally controllable and side-effect-free alternative to conventional chemotherapy. The current study provides extensive evidence that a 5 mM concentration of Ca²⁺ in combination with US alone or US and Sonovue MBs can be an alternative to the conventional 20 nM concentration of the anticancer drug bleomycin (BLM). Ca²⁺ application together with SP induces a similar level of death in Chinese hamster ovary cells to the combination of BLM and SP but does not cause systemic toxicity, as is inherent to conventional anticancer drugs. In addition, Ca²⁺ delivery via SP alters three vital characteristics essential for viable cells: membrane permeability, metabolic activity and proliferation ability. Most importantly, Ca²⁺ delivery via SP elicits sudden cell death-occurring within 15 min-which remains similar during 24-72 h and 6 d periods. The extensive study of US waves side-scattered by MBs led to the quantification of the cavitation dose (CD) separately for subharmonics, ultraharmonics, harmonics and broadband noise (up to 4 MHz). The CD was suitable for the prognostication of the cytotoxic efficiency of both anticancer agents, Ca²⁺ and BLM, as was indicated by an overall high (R² ≥ 0.8) correlation (22 pairs in total). These extensive analytical data imply that a broad range of frequencies are applicable for the feedback-loop control of the process of US-mediated Ca²⁺ or BLM delivery, successively leading to the eventual standardization of the protocols for the sonotransfer of anticancer agents as well as the establishment of a universal cavitation dosimetry model.

Nanoelectropulse delivery for cell membrane perturbation and oxidation in human colon adenocarcinoma cells with drug resistance

Ultrashort electric pulses in the nanosecond range (nsPEF) can affect extra- and intracellular lipid structures and can also alternate cell functioning reversibly and irreversibly. Several of the nsPEF effects are due to the abrupt rise in intracellular free calcium levels and calcium ions influx from the outside. Calcium is one of the most important factors in cell proliferation, differentiation, and cell death (apoptosis or necrosis). Manipulating calcium levels using electroporation can have different effects on normal and malignant cells. This study aimed to examine the impact of nsPEFs, combined with 1 mM Ca²⁺ in human colon adenocarcinoma cell lines: sensitive- LoVo and drug resistant-LoVoDX. In this study 200 pulses of 10 ns and high voltage (12.5-50 kVcm^-1) were used. Cell viability was determined by MTT and clonogenic assay. Proteasomal activity, GSH/GSSG assay, ROS production, and PALS-1 protein were evaluated as oxidative stress markers and protein damage. Cell morphology was visualized by AFM, SEM, and confocal microscopy imaging. The results revealed that nsPEF with 1 mM Ca²⁺ is cytotoxic, particularly for LoVoDX cells, and safe for normal cells. NsPEF provoked ROS release, altered cell polarity, and destabilized cell morphology. These results can be important for future protocols for colon adenocarcinoma using calcium nsPEF.

Enhancing electroporation-induced liposomal drug release in suspension and solid phases

When exposed to an external electric field, lipid bilayer membranes are subject to increased permeability through the generation of pores. Combining this phenomenon, known as electroporation, with liposomal drug delivery offers the added benefit of on-demand release of the liposomal cargo. In previous studies, the maximum percent drug release when exposing liposomes to a pulsed electric field has not surpassed 30%, indicating most of the drug is still retained in the liposomes. Here we showed that by modulating the fluidity of the liposome membrane through appropriate selection of the primary lipid, as well as the addition of other fluidity modulating components such as cholesterol and biotinylated lipid, the electroporation-induced percent release could be increased to over 50%. In addition to improved induced release from liposomes in suspension, biomaterial scaffold-bound liposomes were developed. Electroporation-induced protein release from this solid phase was verified after performing further optimization of the liposome formulation to achieve increased stability at physiological temperatures. Collectively, this work advances the ability to achieve efficient electroporation-induced liposomal drug delivery, which has the potential to be used in concert with other clinical applications of electroporation, such as gene electrotransfer and irreversible electroporation (IRE), in order to synergistically increase treatment efficacy.

Electrochemotherapy as an Effective Alternative in the Treatment of Local Advanced Oral Squamous Cell Carcinoma: A Retrospective Analysis of Treated Cases

Advanced oral squamous cell carcinomas represent a major challenge for maxillofacial surgeons, oncologists and radiation therapists. They also account for a large share of healthcare costs. They respond little and/or poorly to conventional therapies (surgery, radiotherapy and chemotherapy). Electrochemotherapy is a new method used as a palliative treatment in patients with advanced cancer of the neck/head region who are not eligible for standard therapies. It combines the use of cytotoxic drugs with the physical principle of electroporation; it effectively controls the tumour locally and preserves organ function. To date, ECT has been little used for oral mucosal tumours, as this is difficult to access for electrodes. We report six cases of advanced oral squamous cell carcinoma treated with electrochemotherapy. This study aims to assess the debulking effect of cancer via ECT in patients with advanced oral squamous cell carcinoma. It also aims to assess the safety and tolerability of this treatment.

Reactive oxygen species-upregulating nanomedicines towards enhanced cancer therapy

Reactive oxygen species (ROS) play a crucial role in physiological and pathological processes, emerging as a therapeutic target in cancer. Owing to the high concentration of ROS in solid tumor tissues, ROS-based treatments, such as photodynamic therapy and chemodynamic therapy, and ROS-responsive drug delivery systems have been widely explored to powerfully and specifically suppress tumors. However, their anticancer efficacy is still hampered by the heterogeneous ROS levels, and thus comprehensively upregulating the ROS levels in tumor tissues can ensure an enhanced therapeutic effect, which can further sensitize and/or synergize with other therapies to inhibit tumor growth and metastasis. Herein, we review the recently emerging drug delivery strategies and technologies for increasing the H₂O₂, ˙OH, ¹O₂, and ˙O₂^- concentrations in cancer cells, including the efficient delivery of natural enzymes, nanozymes, small molecular biological molecules, and nanoscale Fenton-reagents and semiconductors and neutralization of intracellular antioxidant substances and localized input of mechanical and electromagnetic waves (such as ultrasound, near infrared light, microwaves, and X-rays). The applications of these ROS-upregulating nanosystems in enhancing and synergizing cancer therapies including chemotherapy, chemodynamic therapy, phototherapy, and immunotherapy are surveyed. In addition, we discuss the challenges of ROS-upregulating systems and the prospects for future studies.

Nanosecond Pulsed Electric Field (nsPEF): Opening the Biotechnological Pandora’s Box

Nanosecond Pulsed Electric Field (nsPEF) is an electrostimulation technique first developed in 1995; nsPEF requires the delivery of a series of pulses of high electric fields in the order of nanoseconds into biological tissues or cells. They primary effects in cells is the formation of membrane nanopores and the activation of ionic channels, leading to an incremental increase in cytoplasmic Ca2+ concentration, which triggers a signaling cascade producing a variety of effects: from apoptosis up to cell differentiation and proliferation. Further, nsPEF may affect organelles, making nsPEF a unique tool to manipulate and study cells. This technique is exploited in a broad spectrum of applications, such as: sterilization in the food industry, seed germination, anti-parasitic effects, wound healing, increased immune response, activation of neurons and myocites, cell proliferation, cellular phenotype manipulation, modulation of gene expression, and as a novel cancer treatment. This review thoroughly explores both nsPEF’s history and applications, with emphasis on the cellular effects from a biophysics perspective, highlighting the role of ionic channels as a mechanistic driver of the increase in cytoplasmic Ca2+ concentration.

Electrochemotherapy of Primary Colon Rectum Cancer and Local Recurrence: Case Report and Prospective Analysis

Purpose: Surgery, radiotherapy, and oncological treatment (chemotherapy and antineoplastic antibodies) are standard treatments of rectal cancer. ECT has shown its effectiveness and suitability in deep solid tumors conducted in both preclinical and clinical studies. We show here an update and preliminary results with locally advanced rectum cancer (LARC) treated with ECT. Methods: Two patients with major clinical response to restaging after neoadjuvant treatment for LARC were subjected to ECT 12 weeks after completing chemo-radiation therapy. One patient was subjected to ECT on a colorectal local recurrence formed after neoadjuvant treatment for LARC and surgery. Computed Tomography and Magnetic Resonance Imaging were used to assess ECT response. Results: The results showed stable disease in two of the three patients treated, while one patient achieved a complete response. The local control of disease is maintained in the patient follow-up. For each patient, a reduction in pain was observed and for the patient with local recurrence, a reduction in bleeding present before ECT was also achieved. Conclusion: Preliminary results showed that ECT is a safe and effective treatment in patients with a major clinical response or local recurrence after neoadjuvant therapy for LARC and allows a reduction in pain and bleeding with a consequent improvement to quality of life.

Use of electrochemotherapy in a combined surgical treatment of local recurrence of rectal cancer

Recurrence of rectal cancer (RRC) affects up to one-third of patients. The survival is strictly dependent on the possibility of performing surgery without microscopic tumor residues (R0). Electrochemotherapy (ECT) is based on the effect that electric pulsations have on increasing the permeability of the cell membrane to certain drugs. We propose the association of ECT to the surgical excision of perineal RRC in a 72-year-old male patient. Given the proximity between the recurrence and the urethra, it was decided to use ECT in order to clean any further neoplastic residues 10 mm from the surgical resection margin. Pelvic MRI at 4 and 7 months and clinical follow-up conducted for 9 months did not document disease recurrence. ECT combined with surgery can prove to be a valid choice in selected cases and could be the best treatment the patient is willing to accept.

Electrotherapies for Glioblastoma

Non-thermal, intermediate frequency (100-500 kHz) electrotherapies present a unique therapeutic strategy to treat malignant neoplasms. Here, pulsed electric fields (PEFs) which induce reversible or irreversible electroporation (IRE) and tumour-treating fields (TTFs) are reviewed highlighting the foundations, advances, and considerations of each method when applied to glioblastoma (GBM). Several biological aspects of GBM that contribute to treatment complexity (heterogeneity, recurrence, resistance, and blood-brain barrier(BBB)) and electrophysiological traits which are suggested to promote glioma progression are described. Particularly, the biological responses at the cellular and molecular level to specific parameters of the electrical stimuli are discussed offering ways to compare these parameters despite the lack of a universally adopted physical description. Reviewing the literature, a disconnect is found between electrotherapy techniques and how they target the biological complexities of GBM that make treatment difficult in the first place. An attempt is made to bridge the interdisciplinary gap by mapping biological characteristics to different methods of electrotherapy, suggesting important future research topics and directions in both understanding and treating GBM. To the authors' knowledge, this is the first paper that attempts an in-tandem assessment of the biological effects of different aspects of intermediate frequency electrotherapy methods, thus offering possible strategies toward GBM treatment.

Alternative methods for local ablation-interventional pulmonology: a narrative review

OBJECTIVE

To discuss and summarise the background and recent advances in the approach to bronchoscopic ablative therapies for lung cancer, focusing on focal parenchymal lesions.

BACKGROUND

This series focusses on the challenges highlighted by increasing recognition of the prognostically more favourable oligometastatic disease rather than the more frequent, but prognostically poor, high tumour burden metastatic disease. While surgery, stereotactic body radiation therapy (SBRT), and trans-thoracic percutaneous ablative techniques such as microwave (MWA) and radiofrequency ablation (RFA) are well recognised options for selected cases of pulmonary oligometastasis, bronchoscopic approaches to pulmonary tumour ablation are becoming realistic alternatives. An underlying tenet driving research and implementation in this domain is that percutaneous ablative techniques are obliged to traverse the pleura leading to a high rate of pneumothorax, and risks also goes up for peri-vascular lesions. Historically low yield bronchoscopic targeting of isolated peripheral tumors have significantly improved by incorporating multi-modality high resolution imaging and processing, including navigation planning and real-time image guidances (ultrasound, electromagnetic navigation, cone-beam CT). Combining advanced image guidance with ablative technology adaptations for bronchoscopic delivery opens up the options for high dose local ablative therapies that may reduce transthoracic complications and provide palliative to curative options for limited stage primary and oligometastatic diseases.

METHODS

We conduct a narrative review of the literature summarizing the history of bronchoscopic tumor ablation approaches, technical details including biologic rational for their uses, and current evidence for each modality, as well as investigations into future applications. Because of the relative paucity of prospective studies, we have been very inclusive in our inclusion of experiences from the published clinical databases.

CONCLUSIONS

Whilst surgical resection and SBRT remain the current mainstay of curative therapies for peripheral cancers, in the foreseeable future, developments and further research will see bronchoscopic ablative therapies become viable lung sparing alternatives in those deemed suitable. The future is bright.

Exploring the Conformational Changes Induced by Nanosecond Pulsed Electric Fields on the Voltage Sensing Domain of a Ca2+ Channel

Nanosecond Pulsed Electric Field (nsPEF or Nano Pulsed Stimulation, NPS) is a technology that delivers a series of pulses of high-voltage electric fields during a short period of time, in the order of nanoseconds. The main consequence of nsPEF upon cells is the formation of nanopores, which is followed by the gating of ionic channels. Literature is conclusive in that the physiological mechanisms governing ion channel gating occur in the order of milliseconds. Hence, understanding how these channels can be activated by a nsPEF would be an important step in order to conciliate fundamental biophysical knowledge with improved nsPEF applications. To get insights on both the kinetics and thermodynamics of ion channel gating induced by nsPEF, in this work, we simulated the Voltage Sensing Domain (VSD) of a voltage-gated Ca2+ channel, inserted in phospholipidic membranes with different concentrations of cholesterol. We studied the conformational changes of the VSD under a nsPEF mimicked by the application of a continuous electric field lasting 50 ns with different intensities as an approach to reveal novel mechanisms leading to ion channel gating in such short timescales. Our results show that using a membrane with high cholesterol content, under an nsPEF of 50 ns and E→ = 0.2 V/nm, the VSD undergoes major conformational changes. As a whole, our work supports the notion that membrane composition may act as an allosteric regulator, specifically cholesterol content, which is fundamental for the response of the VSD to an external electric field. Moreover, changes on the VSD structure suggest that the gating of voltage-gated Ca2+ channels by a nsPEF may be due to major conformational changes elicited in response to the external electric field. Finally, the VSD/cholesterol-bilayer under an nsPEF of 50 ns and E→ = 0.2 V/nm elicits a pore formation across the VSD suggesting a new non-reported effect of nsPEF into cells, which can be called a “protein mediated electroporation”.

Bleomycin administered by laser-assisted drug delivery or intradermal needle-injection results in distinct biodistribution patterns in skin: in vivo investigations with mass spectrometry imaging

Bleomycin (BLM) is being repositioned in dermato-oncology for intralesional and intra-tumoural use. Although conventionally administered by local needle injections (NIs), ablative fractional lasers (AFLs) can facilitate topical BLM delivery. Adding local electroporation (EP) can augment intracellular uptake in the target tissue. Here, we characterize and compare BLM biodistribution patterns, cutaneous pharmacokinetic profiles, and tolerability in an in vivo pig model following fractional laser-assisted topical drug delivery and intradermal NI, with and without subsequent EP. In vivo pig skin was treated with AFL and topical BLM or NI with BLM, alone or with additional EP, and followed for 1, 2 and 4 h and eventually up to 9 d. BLM biodistribution was assessed by spatiotemporal mass spectrometry imaging. Cutaneous pharmacokinetics were assessed by mass spectrometry quantification and temporal imaging. Tolerability was evaluated by local skin reactions (LSRs) and skin integrity measurements. AFL and NI resulted in distinct BLM biodistributions: AFL resulted in a horizontal belt-shaped BLM distribution along the skin surface, and NI resulted in BLM radiating from the injection site. Cutaneous pharmacokinetic analyses and temporal imaging showed a substantial reduction in BLM concentration within the first few hours following administration. LSRs were tolerable overall, and all interventions permitted almost complete recovery of skin integrity within 9 d. In conclusion, AFL and NI result in distinct cutaneous biodistribution patterns and pharmacokinetic profiles for BLM applied to in vivo skin. Evaluation of LSRs showed that both methods were similarly tolerable, and each method has potential for individualized approaches in a clinical setting.

Reduction of muscle contraction and pain in electroporation-based treatments: An overview

BACKGROUND

In the first studies of electrochemotherapy (ECT), small cutaneous metastases were treated and only mild or moderate pain was observed; therefore, pain was not considered a significant issue. As the procedure began to be applied to larger cutaneous metastases, pain was reported more frequently. For that reason, reduction of both muscle contractions and pain have been investigated over the years.

AIM

To present an overview of different protocols described in literature that aim to reduce muscle contractions and pain caused by the electroporation (EP) effect in both ECT and irreversible EP treatments.

METHODS

Thirty-three studies published between January 1999 and November 2020 were included. Different protocol designs and electrode geometries that reduce patient pain and the number of muscle contractions and their intensity were analysed.

RESULTS

The analysis showed that both high frequency and bipolar/biphasic pulses can be used to reduce pain and muscle contractions in patients who undergo EP treatments. Moreover, adequate electrode design can decrease EP-related morbidity. Particularly, needle length, diameter and configuration of the distance between the needles can be optimised so that the muscle volume crossed by the current is reduced as much as possible. Bipolar/biphasic pulses with an inadequate pulse length seem to have a less evident effect on the membrane permeability compared with the standard pulse protocol. For that reason, the number of pulses and the voltage amplitude, as well as the pulse duration and frequency, must be chosen so that the dose of delivered energy guarantees EP efficacy.

CONCLUSION

Pain reduction in EP-based treatments can be achieved by appropriately defining the protocol parameters and electrode design. Most results can be achieved with high frequency and/or bipolar/biphasic pulses. However, the efficacy of these alternative protocols remains a crucial point to be assessed further.

A Systematic Review about Imaging and Histopathological Findings for Detecting and Evaluating Electroporation Based Treatments Response

BACKGROUND

Imaging methods and the most appropriate criteria to be used for detecting and evaluating response to oncological treatments depend on the pathology and anatomical site to be treated and on the treatment to be performed. This document provides a general overview of the main imaging and histopathological findings of electroporation-based treatments (Electrochemotherapy-ECT and Irreversible electroporation-IRE) compared to thermal approach, such as radiofrequency ablation (RFA), in deep-seated cancers with a particular attention to pancreatic and liver cancer.

METHODS

Numerous electronic datasets were examined: PubMed, Scopus, Web of Science and Google Scholar. The research covered the years from January 1990 to April 2021. All titles and abstracts were analyzed. The inclusion criteria were the following: studies that report imaging or histopathological findings after ablative thermal and not thermal loco-regional treatments (ECT, IRE, RFA) in deep-seated cancers including pancreatic and liver cancer and articles published in the English language. Exclusion criteria were unavailability of full text and congress abstracts or posters and different topic respect to inclusion criteria.

RESULTS

558 potentially relevant references through electronic searches were identified. A total of 38 articles met the inclusion criteria: 20 studies report imaging findings after RFA or ECT or IRE in pancreatic and liver cancer; 17 studies report histopathological findings after RFA or ECT or IRE; 1 study reports both imaging and histopathological findings after RFA or ECT or IRE.

CONCLUSIONS

Imaging features are related to the type of therapy administrated, to the timing of re-assessment post therapy and to the imaging technique being used to observe the effects. Histological findings after both ECT and IRE show that the treated area becomes necrotic and encapsulated in fibrous tissue, suggesting that the size of the treated lesion cannot be measured as an endpoint to detect response. Moreover, histology frequently reported signs of apoptosis and reduced vital tissue, implying that imaging criteria, which take into account the viability and not the size of the lesion, are more appropriate to evaluate response to treatment.

A nanosecond pulsed electric field (nsPEF) can affect membrane permeabilization and cellular viability in a 3D spheroids tumor model

Three-dimensional (3D) cellular models represent more realistically the complexity of in vivo tumors compared to 2D cultures. While 3D models were largely used in classical electroporation, the effects of nanosecond pulsed electric field (nsPEF) have been poorly investigated. In this study, we evaluated the biological effects induced by nsPEF on spheroid tumor model derived from the HCT-116 human colorectal carcinoma cell line. By varying the number of pulses (from 1 to 500) and the polarity (unipolar and bipolar), the response of nsPEF exposure (10 ns duration, 50 kV/cm) was assessed either immediately after the application of the pulses or over a period lasting up to 6 days. Membrane permeabilization and cellular death occurred following the application of at least 100 pulses. The extent of the response increased with the number of pulses, with a significant decrease of viability, 24 h post-exposure, when 250 and 500 pulses were applied. The effects were highly reduced when an equivalent number of bipolar pulses were delivered. This reduction was eliminated when a 100 ns interphase interval was introduced into the bipolar pulses. Altogether, our results show that nsPEF effects, previously observed at the single cell level, also occur in more realistic 3D tumor spheroids models.

Electrochemotherapy in Vulvar Cancer and Cisplatin Combined with Electroporation. Systematic Review and In Vitro Studies

Simple Summary

Electrochemotherapy (ECT) is an emerging treatment for solid tumors and an attracting research field due to its clinical results. ECT in association with bleomycin is an effective and safe treatment option in the vulvar cancer palliative setting. With regard to cisplatin (CSP)-based ECT, considering the clear evidence on its efficacy in gynecological tumors, the possibility to improve local control with CSP-based ECT is intriguing and a well-designed randomized clinical trial should be addressed to this issue.

Abstract

Electrochemotherapy (ECT) is an emerging treatment for solid tumors and an attractive research field due to its clinical results. This therapy represents an alternative local treatment to the standard ones and is based on the tumor-directed delivery of non-ablative electrical pulses to maximize the action of specific cytotoxic drugs such as cisplatin (CSP) and bleomycin (BLM) and to promote cancer cell death. Nowadays, ECT is mainly recommended as palliative treatment. However, it can be applied to a wide range of superficial cancers, having an impact in preventing or delaying tumor progression and therefore in improving quality of life. In addition, during the natural history of the tumor, early ECT may improve patient outcomes. Our group has extensive clinical and research experience on ECT in vulvar tumors in the palliative setting, with 70% overall response rate. So far, in most studies, ECT was based on BLM. However, the potential of CSP in this setting seems interesting due to some theoretical advantages. The purpose of this report is to: (i) compare the efficacy of CSP and BLM-based ECT through a systematic literature review; (ii) report the results of our studies on CSP-resistant squamous cell tumors cell lines and the possibility to overcome chemoresistance using ECT; (iii) discuss the future ECT role in gynecological tumors and in particular in vulvar carcinoma.

Irreversible Electroporation (IRE) in Locally Advanced Pancreatic Cancer: A Review of Current Clinical Outcomes, Mechanism of Action and Opportunities for Synergistic Therapy

Locally advanced pancreatic cancer (LAPC) accounts for 30% of patients with pancreatic cancer. Irreversible electroporation (IRE) is a novel cancer treatment that may improve survival and quality of life in LAPC. This narrative review will provide a perspective on the clinical experience of pancreas IRE therapy, explore the evidence for the mode of action, assess treatment complications, and propose strategies for augmenting IRE response. A systematic search was performed using PubMed regarding the clinical use and safety profile of IRE on pancreatic cancer, post-IRE sequential histological changes, associated immune response, and synergistic therapies. Animal data demonstrate that IRE induces both apoptosis and necrosis followed by fibrosis. Major complications may result from IRE; procedure related mortality is up to 2%, with an average morbidity as high as 36%. Nevertheless, prospective and retrospective studies suggest that IRE treatment may increase median overall survival of LAPC to as much as 30 months and provide preliminary data justifying the well-designed trials currently underway, comparing IRE to the standard of care treatment. The mechanism of action of IRE remains unknown, and there is a lack of data on treatment variables and efficiency in humans. There is emerging data suggesting that IRE can be augmented with synergistic therapies such as immunotherapy.

Electrochemotherapy in the Treatment of Head and Neck Cancer: Current Conditions and Future Directions

Simple Summary

Electrochemotherapy (ECT) was first introduced in the late 1980s and was initially used mainly on cutaneous tumors. It has now evolved into a clinically verified treatment approach. Thanks to its high feasibility, it has been extended to treating mucosal and deep-seated tumors, including head and neck cancer (HNC) and in heavily pretreated settings. This review describes current knowledge and data on the use of ECT in various forms of HNCs across different clinical settings, with attention to future clinical and research perspectives.

Abstract

Despite recent advances in the development of chemotherapeutic drug, treatment for advanced cancer of the head and neck cancer (HNC) is still challenging. Options are limited by multiple factors, such as a prior history of irradiation to the tumor site as well as functional limitations. Against this background, electrochemotherapy (ECT) is a new modality which combines administration of an antineoplastic agent with locally applied electric pulses. These pulses allow the chemotherapeutic drug to penetrate the intracellular space of the tumor cells and thereby increase its cytotoxicity. ECT has shown encouraging efficacy and a tolerable safety profile in many clinical studies, including in heavily pre-treated HNC patients, and is considered a promising strategy. Efforts to improve its efficacy and broaden its application are now ongoing. Moreover, the combination of ECT with recently developed novel therapies, including immunotherapy, represented by immune checkpoint inhibitor (ICI)s, has attracted attention for its potent theoretical rationale. More extensive, well-organized clinical studies and timely updating of consensus guidelines will bring this hopeful treatment to HNC patients under challenging situations.

Electrochemotherapy in Mucosal Cancer of the Head and Neck: A Systematic Review

Electrochemotherapy (ECT) is a local ablative treatment that is based on the reversible electroporation and intracellular accumulation of hydrophilic drug molecules, which greatly increases their cytotoxicity. In mucosal head and neck cancer (HNC), experience with ECT is limited due to the poor accessibility of tumors. In order to review the experience with ECT in mucosal HNC, we undertook a systematic review of the literature. In 22 articles, published between 1998 and 2020, 16 studies with 164 patients were described. Curative and palliative intent treatment were given to 36 (22%) and 128 patients (78%), respectively. The majority of tumors were squamous cell carcinomas (79.3%) and located in the oral cavity (62.8%). In the curative intent group, complete response after one ECT treatment was achieved in 80.5% of the patients, and in the palliative intent group, the objective (complete and partial) response rate was 73.1% (31.2% and 41.9%). No serious adverse events were reported during or soon after ECT and late effects were rare (19 events in 17 patients). The quality-of-life assessments did not show a significant deterioration at 12 months post-ECT. Provided these preliminary data are confirmed in randomized controlled trials, ECT may be an interesting treatment option in selected patients with HNC not amenable to standard local treatment.

The effect of calcium electroporation on viability, phenotype and function of melanoma conditioned macrophages

Electroporation in combination with chemotherapy is an established treatment used on solid malignancies that results in enhanced chemotherapeutic uptake. Recent advances have begun to transition to the use of non-toxic compounds, such as calcium, in lieu of chemotherapy, which can also induce tumour cell death. While the effect of treatment on tumour cell death has been well characterized and has been shown to induce an immunogenic form of cell death, the effect of treatment on intratumoural immune cells has not been investigated. Here we present data showing the effect of calcium electroporation on immune cells, using melanoma-conditioned bone marrow-derived macrophages. Similar to tumour cells, macrophage cell membranes are susceptible to poration following treatment and subsequently reseal. Macrophages are less susceptible to calcium electroporation induced cell death in comparison to B16F10 melanoma cells. However treatment with electroporation with or without bleomycin or calcium was shown to affect macrophage phenotype and function. Coculture of calcium electroporated macrophages revealed that both the capacity of macrophages to stimulate and direct T cell responses are affected following exposure to treatment. We conclude that calcium electroporation has the potential to boost the immunogenic capacity of exposed tumour associated macrophages, and further research is warranted to determine if calcium electroporation can be optimised to generate systemic anti-cancer immune responses.

In Vitro Experimental and Numerical Studies on the Preferential Ablation of Chemo-Resistant Tumor Cells Induced by High-Voltage Nanosecond Pulsed Electric Fields

Chemoresistance causes tumor recurrence and metastasis, resulting in poor clinical outcomes and low survival, and has been considered an obstacle to tumor therapy. The development of novel therapeutic approaches that can effectively kill chemoresistant tumor cells (CRTCs) is therefore critical to overcoming these obstacles.

OBJECTIVE

Here, we introduce an emerging physical feature-based therapeutic approach based on nanosecond pulsed electric fields (nsPEFs). The goal of this study is to investigate the effect of nsPEFs on CRTCs.

METHODS

The cell viability, ablation effects on a 3D-cultured scaffold, and lethal thresholds of nsPEFs were evaluated according to fluorescence staining assays.

RESULTS

nsPEF treatment preferentially affected chemoresistant cells (A549/CDDP) with a higher cell viability inhibition ability/cell death rate, larger ablation area, and lower ablation threshold compared to their respective homologous tumor cells (A549). The experimental and theoretical studies suggested that nsPEFs displayed selective behavior toward intracellular structures. With this selective character, nsPEFs can induce higher electroporation effects (e.g., higher pore number, larger electroporation area, and faster fluorescence dissipation on the nuclear envelope) on CRTCs due to their larger nuclear size and cell membrane capacitance.

CONCLUSION

These findings demonstrated that nsPEFs induced preferential ablation of CRTCs over their respective homologous tumor cells.

SIGNIFICANCE

This study provides an experimental and theoretical basis for the study of killing CRTCs by electrical treatments and suggests potential applications in the optimization of novel anti-chemoresistance methods.

Electrochemotherapy of skin metastases from breast cancer: a systematic review

Skin metastases occur in 5-30% of breast cancer (BC) patients. Standard treatments include systemic therapies (chemotherapy, endocrine therapy, and immunotherapy) and local treatments (surgery and radiotherapy). Electrochemotherapy (ECT) could be another option in this setting based on preclinical and clinical studies. Aim of this review was to analyze the available evidence on ECT in skin metastases from BC. Studies reporting on ECT in skin metastases from BC were included in this review. Studies not reporting toxicity or tumor response or not reporting results separately from other primary cancers were excluded. The search was based on Medline, Scopus, and The Cochrane Library databases. Eleven studies including 464 patients were analyzed. ECT was performed using intravenous/intratumoral bleomycin (10 studies) or intratumoral cisplatin (one study). Complete and overall pooled response rates were 46.2% (_95%CI 33.2-59.4 and 74.6% (_95%CI 60.6-86.4) in studies reporting results on a per patient basis and 61.9% (_95%CI 53.8-69.6) and 86.9% (_95%CI 80.0-92.6) in studies reporting results on a per lesion basis, respectively. Worse response rates in larger lesions were observed in three studies. The incidence of toxicity was heterogeneous but adverse events were mild and manageable in all studies. One- and 3-year local progression-free survival was 86.2% and 81.0% in two studies, respectively. ECT is tolerable and effective in terms of response in BC skin metastases especially in less advanced lesions. Further studies are justified to compare ECT with other treatments in this setting.

Electroporation-Based Treatments in Small Animal Veterinary Oral and Maxillofacial Oncology

Electroporation is a method of inducing an increase in permeability of the cell membrane through the application of an electric field and can be used as a delivery method for introducing molecules of interest (e.g., chemotherapeutics or plasmid DNA) into cells. Electroporation-based treatments (i.e., electrochemotherapy, gene electrotransfer, and their combinations) have been shown to be safe and effective in veterinary oncology, but they are currently mostly recommended for the treatment of those solid tumors for which clients have declined surgery and/or radiotherapy. Published data show that electroporation-based treatments are also safe, simple, fast and cost-effective treatment alternatives for selected oral and maxillofacial tumors, especially small squamous cell carcinoma and malignant melanoma tumors not involving the bone in dogs. In these patients, a good local response to treatment is expected to result in increased survival time with good quality of life. Despite emerging evidence of the clinical efficacy of electroporation-based treatments for oral and maxillofacial tumors, further investigation is needed to optimize treatment protocols, improve clinical data reporting and better understand the mechanisms of patients' response to the treatment.

Modeling iontophoretic drug delivery in a microfluidic device

Iontophoresis employs low-intensity electrical voltage and continuous constant current to direct a charged drug into a tissue. Iontophoretic drug delivery has recently been used as a novel method for cancer treatment in vivo. There is an urgent need to precisely model the low-intensity electric fields in cell culture systems to optimize iontophoretic drug delivery to tumors. Here, we present an iontophoresis-on-chip (IOC) platform to precisely quantify carboplatin drug delivery and its corresponding anti-cancer efficacy under various voltages and currents. In this study, we use an in vitro heparin-based hydrogel microfluidic device to model the movement of a charged drug across an extracellular matrix (ECM) and in MDA-MB-231 triple-negative breast cancer (TNBC) cells. Transport of the drug through the hydrogel was modeled based on diffusion and electrophoresis of charged drug molecules in the direction of an oppositely charged electrode. The drug concentration in the tumor extracellular matrix was computed using finite element modeling of transient drug transport in the heparin-based hydrogel. The model predictions were then validated using the IOC platform by comparing the predicted concentration of a fluorescent cationic dye (Alexa Fluor 594®) to the actual concentration in the microfluidic device. Alexa Fluor 594® was used because it has a molecular weight close to paclitaxel, the gold standard drug for treating TNBC, and carboplatin. Our results demonstrated that a 50 mV DC electric field and a 3 mA electrical current significantly increased drug delivery and tumor cell death by 48.12% ± 14.33 and 39.13% ± 12.86, respectively (n = 3, p-value <0.05). The IOC platform and mathematical drug delivery model of iontophoresis are promising tools for precise delivery of chemotherapeutic drugs into solid tumors. Further improvements to the IOC platform can be made by adding a layer of epidermal cells to model the skin.

Design and Characterization of a Minimally Invasive Bipolar Electrode for Electroporation

OBJECTIVE

To test a new bipolar electrode for electroporation consisting of a single minimally invasive needle.

METHODS

A theoretical study was performed by using Comsol Multiphysics^® software. The prototypes of electrode have been tested on potatoes and pigs, adopting an irreversible electroporation protocol. Different applied voltages and different geometries of bipolar electrode prototype have been evaluated.

RESULTS

Simulations and pre-clinical tests have shown that the volume of ablated area is mainly influenced by applied voltage, while the diameter of the electrode had a lesser impact, making the goal of minimal-invasiveness possible. The conductive pole's length determined an increase of electroporated volume, while the insulated pole length inversely affects the electroporated volume size and shape; when the insulated pole length decreases, a more regular shape of the electric field is obtained. Moreover, the geometry of the electrode determined a different shape of the electroporated volume. A parenchymal damage in the liver of pigs due to irreversible electroporation protocol was observed.

CONCLUSION

The minimally invasive bipolar electrode is able to treat an electroporated volume of about 10 mm in diameter by using a single-needle electrode. Moreover, the geometry and the electric characteristics can be selected to produce ellipsoidal ablation volumes.

To breathe or not to breathe? Hypoxia after pulsed-electric field treatment reduces the effectiveness of electrochemotherapy in vitro

Bleomycin, which is the most widely used drugs in electrochemotherapy, requires oxygen to be able to make single- or double-strand brakes in DNA. However, the concentration of oxygen in tumours can be lower than 1%. The aim of this study was to find out whether oxygen concentration in the medium in which cells loaded with bleomycin are incubated, affects the effectiveness of electrochemotherapy in vitro. Experiments were carried out on mouse hepatoma MH-22A cells. Cells were loaded with bleomycin by using a single square-wave electric pulse (2 kV/cm, 100 μs) under normoxic conditions, seeded into Petri dishes, and grown under normoxic and hypoxic conditions. Cell viability was determined by means of a colony-forming assay. We demonstrated that when cells loaded with bleomycin were incubated in hypoxia (0.2% O₂), up to 5.3-fold higher concentrations of bleomycin were needed to kill them in comparison with cells grown in normoxia (18.7% O₂).

Electrochemotherapy in the treatment of cutaneous malignancy: Outcomes and subgroup analysis from the cumulative results from the pan-European International Network for Sharing Practice in Electrochemotherapy database for 2482 lesions in 987 patients (2008-2019)

BACKGROUND

Electrochemotherapy (ECT) is a treatment for both primary and secondary cutaneous tumours. The international Network for sharing practices on ECT group investigates treatment outcomes after ECT using a common database with defined parameters.

METHODS

Twenty-eight centres across Europe prospectively uploaded data over an 11-year period. Response rates were investigated in relation to primary diagnosis, tumour size, choice of electrode type, route of bleomycin administration, electrical parameters recorded and previous irradiation in the treated field.

RESULTS

Nine hundred eighty-seven patients, with 2482 tumour lesions were included in analysis. The overall response (OR) rate was 85% (complete response [CR]: 70%, partial response rate: 15%, stable disease: 11%, and progressive disease: 2%). For different histologies, OR and CR rates for metastases of malignant melanoma were 82% and 64%, basal cell carcinoma were 96% and 85%, breast cancer metastases were 77% and 62%, squamous cell carcinoma were 80% and 63% as well as Kaposi's sarcoma were 98% and 91%, respectively. Variance was demonstrated across histotypes (p < 0.0001) and in accordance with size of lesion treated (dichotomised at diameter of 3 cm (p < 0.0001). Hexagonal electrodes were generally used for larger tumours, but for tumours up to 3 cm, linear array electrodes provided better tumour control than hexagonal electrodes (80%:74%, p < 0.003). For tumours more than 2 cm, intravenous administration was superior to intratumoural (IT) administration (p < 0.05). Current recorded varied across tumour histologies and size but did not influence response rate. In previously irradiated areas, responses were selectively lower for IT administration.

CONCLUSIONS

These cumulative data endorse efficiency of ECT across a broad range of histotypes. Analysis of 2482 lesions details subgroup analysis on treatment response informing future treatment choices.

Wireless Electrochemotherapy by Selenium-Doped Piezoelectric Biomaterials to Enhance Cancer Cell Apoptosis

Cancer residues around the surgical site remain a significant cause of treatment failure with cancer recurrence. To prevent cancer recurrence and simultaneously repair surgery-caused defects, it is urgent to develop implantable biomaterials with anticancer ability and good biological activity. In this work, a functionalized implant is successfully fabricated by doping the effective anticancer element selenium (Se) into the potassium-sodium niobate piezoceramic, which realizes the wireless combination of electrotherapy and chemotherapy. Herein, we demonstrate that the Se-doped piezoelectric implant can cause mitochondrial damage by increasing intracellular reactive oxygen species levels and then trigger the caspase-3 pathway to significantly promote apoptosis of osteosarcoma cells in vitro. Meanwhile, its good biocompatibility has been verified. These results are of great importance for future deployment of wireless electro- and chemostimulation to modulate biological process around the defective tissue.

Analysis of damage-associated molecular pattern molecules due to electroporation of cells in vitro

Background Tumor cells can die via immunogenic cell death pathway, in which damage-associated molecular pattern molecules (DAMPs) are released from the cells. These molecules activate cells involved in the immune response. Both innate and adaptive immune response can be activated, causing a destruction of the remaining infected cells. Activation of immune response is also an important component of tumor treatment with electrochemotherapy (ECT) and irreversible electroporation (IRE). We thus explored, if and when specific DAMPs are released as a consequence of electroporation in vitro. Materials and methods In this in vitro study, 100 μs long electric pulses were applied to a suspension of Chinese hamster ovary cells. The release of DAMPs - specifically: adenosine triphosphate (ATP), calreticulin, nucleic acids and uric acid was investigated at different time points after exposing the cells to electric pulses of different amplitudes. The release of DAMPs was statistically correlated with cell permeabilization and cell survival, e.g. reversible and irreversible electroporation. Results In general, the release of DAMPs increases with increasing pulse amplitude. Concentration of DAMPs depend on the time interval between exposure of the cells to pulses and the analysis. Concentrations of most DAMPs correlate strongly with cell death. However, we detected no uric acid in the investigated samples. Conclusions Release of DAMPs can serve as a marker for prediction of cell death. Since the stability of certain DAMPs is time dependent, this should be considered when designing protocols for detecting DAMPs after electric pulse treatment.

Development of adaptive resistance to electric pulsed field treatment in CHO cell line in vitro

Pulsed electric field treatment has increased over the last few decades with successful translation from in vitro studies into different medical treatments like electrochemotherapy, irreversible electroporation for tumor and cardiac tissue ablation and gene electrotransfer for gene therapy and DNA vaccination. Pulsed electric field treatments are efficient but localized often requiring repeated applications to obtain results due to partial response and recurrence of disease. While these treatment times are several orders of magnitude lower than conventional biochemical treatment, it has been recently suggested that cells may become resistant to electroporation in repetitive treatments. In our study, we evaluate this possibility of developing adaptive resistance in cells exposed to pulsed electric field treatment over successive lifetimes. Mammalian cells were exposed to electroporation pulses for 30 generations. Every 5th generation was analyzed by determining permeabilization and survival curve. No statistical difference between cells in control and cells exposed to pulsed electric field treatment was observed. We offer evidence that electroporation does not affect cells in a way that they would become less susceptible to pulsed electric field treatment. Our findings indicate pulsed electric field treatment can be used in repeated treatments with each treatment having equal efficiency to the initial treatment.