Irreversible electroporation: state of the art

Application of triboelectric nanogenerator (TENG) in cancer prevention and adjuvant therapy

Cancer is a malignant tumor that kills about 940,000 people worldwide each year. In addition, about 30-77 % of cancer patients will experience cancer metastasis and recurrence, which can increase the cancer mortality rate without prompt treatment. According to the US Food and Drug Administration, wearable devices can detect several physiological indicators of patients to reflect their health status and adjuvant cancer treatment. Based on the triboelectric effect and electrostatic induction phenomenon, triboelectric nanopower generation (TENG) technology can convert mechanical energy into electricity and drive small electronic devices. This article reviewed the research status of TENG in the areas of cancer prevention and adjuvant therapy. TENG can be used for cancer prevention with advanced sensors. At the same time, electrical stimulation generated by TENG can also be used to help inhibit the growth of cancer cells to reduce the proliferation, recurrence, and metastasis of cancer cells. This review will promote the practical application of TENG in healthcare and provide clean and sustainable energy solutions for wearable bioelectronic systems.

Comparison of Chemotherapy Combined with Percutaneous Electroporation and Chemotherapy Alone in the Management of Locally Advanced Gallbladder Carcinoma (GBC): A Study Protocol

PURPOSE

This study aims to evaluate the feasibility and efficacy of chemotherapy combined with irreversible electroporation (IRE) in patients with locally advanced gallbladder carcinoma (GBC) presenting as gallbladder masses.

MATERIALS AND METHODS

Patients with unresectable GBC masses of size greater than 2 cm and less than 6 cm without evidence of distant metastases and with no contraindication to general anaesthesia will be enrolled in the study. They will be randomized using computer generated table into two arms with 1:1 allocation ratio to include 15 patients in each group. Group I will be the chemotherapy alone arm and Group II will be the combined image-guided irreversible electroporation of the tumour and chemotherapy arm. The primary outcome assessed shall be the clinical benefit rate (complete response, CR; partial response, PR and stable disease, SD) based on the mRECIST criteria and overall survival. The secondary outcome shall be feasibility and safety of the procedure and quality of life pre and post procedure. The quality of life will be assessed by a questionnaire as given by EORTC-Quality of Life Group before starting therapy and 4 weeks after completion of therapy.

EXPECTED GAIN OF KNOWLEDGE

The combined local and systemic effects of irreversible electroporation and systemic chemotherapy respectively may improve the outcomes in inoperable cases of gallbladder carcinoma.

TRIAL REGISTRATION

Clinical Trials Registry - India ( https://ctri.nic.in/Clinicaltrials/advancesearchmain.php ). Identifier: CTRI/2021/05/033803. Primary Register of the International Clinical Trials Registry Platform (WHO ICTRP) ( http://www.who.int/ictrp/search/en/ ).

Investigation of High Frequency Irreversible Electroporation for Canine Spontaneous Primary Lung Tumor Ablation

In this study, the feasibility of treating canine primary lung tumors with high-frequency irreversible electroporation (H-FIRE) was investigated as a novel lung cancer treatment option. H-FIRE is a minimally invasive tissue ablation modality that delivers bipolar pulsed electric fields to targeted cells, generating nanopores in cell membranes and rendering targeted cells nonviable. In the current study, canine patients (n = 5) with primary lung tumors underwent H-FIRE treatment with an applied voltage of 2250 V using a 2-5-2 µs H-FIRE waveform to achieve partial tumor ablation prior to the surgical resection of the primary tumor. Surgically resected tumor samples were evaluated histologically for tumor ablation, and with immunohistochemical (IHC) staining to identify cell death (activated caspase-3) and macrophages (IBA-1, CD206, and iNOS). Changes in immunity and inflammatory gene signatures were also evaluated in tumor samples. H-FIRE ablation was evident by the microscopic observation of discrete foci of acute hemorrhage and necrosis, and in a subset of tumors (n = 2), we observed a greater intensity of cleaved caspase-3 staining in tumor cells within treated tumor regions compared to adjacent untreated tumor tissue. At the study evaluation timepoint of 2 h post H-FIRE, we observed differential gene expression changes in the genes IDO1, IL6, TNF, CD209, and FOXP3 in treated tumor regions relative to paired untreated tumor regions. Additionally, we preliminarily evaluated the technical feasibility of delivering H-FIRE percutaneously under CT guidance to canine lung tumor patients (n = 2). Overall, H-FIRE treatment was well tolerated with no adverse clinical events, and our results suggest H-FIRE potentially altered the tumor immune microenvironment.

Strategies to enhance the therapeutic efficacy of anti-PD-1 antibody, anti-PD-L1 antibody and anti-CTLA-4 antibody in cancer therapy

Although immune checkpoint inhibitors (anti-PD-1 antibody, anti-PD-L1 antibody, and anti-CTLA-4 antibody) have displayed considerable success in the treatment of malignant tumors, the therapeutic effect is still unsatisfactory for a portion of patients. Therefore, it is imperative to develop strategies to enhance the effect of these ICIs. Increasing evidence strongly suggests that the key to this issue is to transform the tumor immune microenvironment from a state of no or low immune infiltration to a state of high immune infiltration and enhance the tumor cell-killing effect of T cells. Therefore, some combination strategies have been proposed and this review appraise a summary of 39 strategies aiming at enhancing the effectiveness of ICIs, which comprise combining 10 clinical approaches and 29 foundational research strategies. Moreover, this review improves the comprehensive understanding of combination therapy with ICIs and inspires novel ideas for tumor immunotherapy.

Dendritic cell vaccination combined with irreversible electroporation for treating pancreatic cancer-a narrative review

Background and Objective

Pancreatic ductal adenocarcinoma (PDAC) is 3rd most lethal cancer in the USA leading to a median survival of six months and less than 5% 5-year overall survival (OS). As the only potentially curative treatment, surgical resection is not suitable for up to 90% of the patients with PDAC due to late diagnosis. Highly fibrotic PDAC with an immunosuppressive tumor microenvironment restricts cytotoxic T lymphocyte (CTL) infiltration and functions causing limited success with systemic therapies like dendritic cell (DC)-based immunotherapy. In this study, we investigated the potential benefits of irreversible electroporation (IRE) ablation therapy in combination with DC vaccine therapy against PDAC.

Methods

We performed a literature search to identify studies focused on DC vaccine therapy and IRE ablation to boost therapeutic response against PDAC indexed in PubMed, Web of Science, and Scopus until February 20th, 2023.

Key Content and Findings

IRE ablation destructs tumor structure while preserving extracellular matrix and blood vessels facilitating local inflammation. The studies demonstrated IRE ablation reduces tumor fibrosis and promotes CTL tumor infiltration to PDAC tumors in addition to boosting immune response in rodent models. The administration of the DC vaccine following IRE ablation synergistically enhances therapeutic response and extends OS rates compared to the use of DC vaccination or IRE alone. Moreover, the implementation of data-driven approaches further allows dynamic and longitudinal monitoring of therapeutic response and OS following IRE plus DC vaccine immunoablation.

Conclusions

The combination of IRE ablation and DC vaccine immunotherapy is a potent strategy to enhance the therapeutic outcomes in patients with PDAC.

Safety and Effectiveness of Irreversible Electroporation in Lymph Node Metastases

PURPOSE

Demonstrating the safety and efficacy of percutaneous irreversible electroporation (IRE) for the treatment of lymph node metastases.

MATERIALS AND METHODS

An IRB-approved, single-center retrospective review was performed on patients with lymph node metastases gastrointestinal, and genitourinary primary cancers. Primary objective safety was evaluated by assessing complications graded according to the Clavien-Dindo Classification, and efficacy was determined by tumor response on follow-up imaging and local progression-free survival (LPFS). Secondary outcome measures were technical success (complete ablation with an adequate ablative margin > 5 mm), length of hospital stay and distant progression-free survival (DPFS).

RESULTS

Nineteen patients underwent percutaneous IRE between June 2018 and February 2023 for lymph node metastases, close to critical structures, such as vasculature, bowel, or nerves. The technical success was achieved in all cases. Complications occurred in four patients (21.1%), including two self-limiting grade 1 hematomas, a grade 1 abdominal pain, and grade 2 nerve pain treated with medication. Seventeen patients were hospitalized overnight, one patient stayed two nights and another patient stayed fourteen nights. Median follow-up was 25.5 months. Median time to local progression was 24.1 months (95% CI: 0-52.8) with 1-, 2-, and 5-year LPFS of 57.9%, 57.9% and 20.7%, respectively. Median time to distant progression was 4.3 months (95% CI: 0.3-8.3) with 1-, 2-, and 5-year DPFS of 31.6%, 13.2% and 13.2%, respectively.

CONCLUSION

IRE is a safe and effective minimally-invasive treatment for lymph node metastases in locations, where temperature dependent ablation may be contraindicated. Care should be taken when employing IRE near nerves.

Ablative Treatments for Small Renal Masses and Management of Recurrences: A Comprehensive Review

This review focuses on ablative techniques for small renal masses (SRMs), including radiofrequency ablation (RFA), cryoablation (CA), microwave ablation (MWA), and irreversible electroporation (IRE), and discusses recurrence management. Through an extensive literature review, we outline the procedures, outcomes, and follow-up strategies associated with each ablative method. The review provides a detailed examination of these techniques-RFA, CA, MWA, and IRE-elucidating their respective outcomes. Recurrence rates vary among them, with RFA and CA showing comparable rates, MWA demonstrating favorable short-term results, and IRE exhibiting promise in experimental stages. For managing recurrences, various strategies are considered, including active surveillance, re-ablation, or salvage surgery. Surveillance is preferred post-RFA and post-CA, due to slow SRM growth, while re-ablation, particularly with RFA and CA, is deemed feasible without additional complications. Salvage surgery emerges as a viable option for larger or resistant tumors. While ablative techniques offer short-term results comparable to surgery, further research is essential to understand their long-term effects fully. Decisions concerning recurrence management should consider individual and tumor-specific factors. Imaging, notably contrast-enhanced ultrasounds, plays a pivotal role in assessing treatment success, emphasizing the necessity of a multidisciplinary approach for optimal outcomes. The lack of randomized trials highlights the need for further research.

Temperature Distribution on Classical Two Needles IRE Setup Versus a Single Needle Prototype

OBJECTIVES

Irreversible Electroporation (IRE) is a non-thermal minimally invasive cancer therapy used in the treatment of liver tumors. However, the therapy entails an electrical current flux which can be high enough to cause a noticeable temperature increase. Therefore, the analysis of the heat distribution is important: during any IRE treatment, the target area is intended to be treated with non-thermal effects, where existing thermal effects should not damage nearby sensitive structures. This article aims to compare the established two parallel needles electrode setup, used by FDA-approved electroporation delivering devices, to a single needle, multiple electrode prototype design.

METHODS

Levels and distributions of the temperature at different distances from the applicators during an IRE liver treatment were investigated. The prototype results were collated with already published in-vivo data. All electrode configurations were analyzed numerically in COMSOL Multiphysics for different pulse protocols.

RESULTS

The extension of coagulation necrosis predicted by the model matched available in-vivo data. While the maximum average temperature during pulsation was higher for the prototype (74 °C) than for the two-needle IRE setup (57 °C), the thickness of the coagulation necrosis around the conductive electrodes was in the same range for both configurations. However, the location differed completely: the necrosis engendered by the prototype was located inside the tumor, while the two-needle IRE setup created necrosis outside the tumor, potentially closer to sensitive structures.

CONCLUSION

The results highlighted the importance of heat distribution analysis for the design of new IRE needles as well as for IRE treatment planning. Proper analysis ensures that the non-thermal effects are maximized while minimizing any potential thermal damage to surrounding sensitive structures.

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.

Clinical translation of abdominal histotripsy: a review of preclinical studies in large animal models

Histotripsy is an emerging noninvasive, non-thermal, and non-ionizing focused ultrasound (US) therapy that can be used to destroy targeted tissue. Histotripsy has evolved from early laboratory prototypes to clinical systems which have been comprehensively evaluated in the preclinical environment to ensure safe translation to human use. This review summarizes the observations and results from preclinical histotripsy studies in the liver, kidney, and pancreas. Key findings from these studies include the ability to make a clinically relevant treatment zone in each organ with maintained collagenous architecture, potentially allowing treatments in areas not currently amenable to thermal ablation. Treatments across organ capsules have proven safe, including in anticoagulated models which may expand patients eligible for treatment or eliminate the risk associated with taking patients off anti-coagulation. Treatment zones are well-defined with imaging and rapidly resorb, which may allow improved evaluation of treatment zones for residual or recurrent tumor. Understanding the effects of histotripsy in animal models will help inform physicians adopting histotripsy for human clinical use.

Protection of high-frequency low-intensity pulsed electric fields and brain-derived neurotrophic factor for SH-SY5Y cells against hydrogen peroxide-induced cell damage

Neurodegenerative diseases (NDDs) pose a significant global health threat. In particular, Alzheimer disease, the most common type causing dementia, remains an incurable disease. Alzheimer disease is thought to be associated with an imbalance of reactive oxygen species (ROS) in neurons, and scientists considered ROS modulation as a promising strategy for novel remedies. In the study, human neural cell line SH-SY5Y was used in probing the effect of combining noninvasive high-frequency low-intensity pulsed electric field (H-LIPEF) and brain-derived neurotrophic factor (BDNF) in protection against hydrogen peroxide (H2O2)-induced neuron damage. Our result finds that the combination approach has intensified the neuroprotective effect significantly, perhaps due to H-LIPEF and BDNF synergistically increasing the expression level of the phosphorylated epidermal growth factor receptor (p-EGFR), which induces the survival-related mitogen-activated protein kinases (MAPK) proteins. The study confirmed the activation of extracellular signal-regulated kinase (ERK) and the downstream pro-survival and antioxidant proteins as the mechanism underlying neuron protection. These findings highlighted the potential of H-LIPEF combined with BDNF in the treatment of NDDs. Furthermore, BDNF-mimetic drugs combining with noninvasive H-LIPEF to patients is a promising approach worthy of further research. This points to strategies for selecting drugs to cooperate with electric fields in treating neurodegenerative disorders.

Self-Expandable Electrode Based on Chemically Polished Nickel-Titanium Alloy Wire for Treating Endoluminal Tumors Using Bipolar Irreversible Electroporation

The application of irreversible electroporation (IRE) to endoluminal organs is being investigated; however, the current preclinical evidence and optimized electrodes are insufficient for clinical translation. Here, a novel self-expandable electrode (SE) made of chemically polished nickel-titanium (Ni-Ti) alloy wire for endoluminal IRE is developed in this study. Chemically polished heat-treated Ni-Ti alloy wires demonstrate increased electrical conductivity, reduced carbon and oxygen levels, and good mechanical and self-expanding properties. Bipolar IRE using chemically polished Ni-Ti wires successfully induces cancer cell death. IRE-treated potato tissue shows irreversibly and reversibly electroporated areas containing dead cells in an electrical strength-dependent manner. In vivo study using an optimized electric field strength demonstrates that endobiliary IRE using the SE evenly induces well-distributed mucosal injuries in the common bile duct (CBD) with the overexpression of the TUNEL, HSP70, and inflammatory cells without ductal perforation or stricture formation. This study demonstrates the basic concept of the endobiliary IRE procedure, which is technically feasible and safe in a porcine CBD as a novel therapeutic strategy for malignant biliary obstruction. The SE is a promising electrical energy delivery platform for effectively treating endoluminal organs.

Probe Contact Force Monitoring during Conductivity Measurements of the Left Atrial Appendage to Support the Design of Novel Diagnostic and Therapeutic Procedures

The electrical properties of many biological tissues are freely available from the INRC and the IT'IS databases. However, particularly in lower frequency ranges, few studies have investigated the optimal measurement protocol or the key confounders that need to be controlled, monitored, and reported. However, preliminary work suggests that the contact force of the measurement probe on the tissue sample can affect the measurements. The aim of this paper is to investigate the conductivity change due to the probe contact force in detail. Twenty ex vivo bovine heart samples are used, and conductivity measurements are taken in the Left Atrial Appendage, a common target for medical device developments. The conductivity measurements reported in this work (between 0.14 S/m and 0.24 S/m) align with the literature. The average conductivity is observed to change by -21% as the contact force increases from 2 N to 10 N. In contrast, in conditions where the fluid concentration in the measurement area is expected to be lower, very small changes are observed (less than 2.5%). These results suggest that the LAA conductivity is affected by the contact force due to the fluid concentration in the tissue. This work suggests that contact force should be controlled for in all future experiments.

Irreversible Electroporation Balloon Therapy for Palliative Treatment of Obstructive Urethral Transitional Cell Carcinoma in Dogs

Progression of transitional cell carcinoma (TCC) in dogs often leads to urinary obstruction. This observational pilot study aimed to evaluate the safety and efficacy of irreversible electroporation (IRE) balloon therapy for the palliative treatment of TCC with partial urethral obstruction. Three client-owned dogs diagnosed with TCC causing partial urethral obstruction were enrolled. After ultrasonographic and cystoscopic examination, IRE pulse protocols were delivered through a balloon catheter device inflated within the urethral lumen. After the procedure, the patients were kept overnight for monitoring and a recheck was planned 28 days later. No complication was observed during the procedure and postprocedural monitoring. After 28 days, one dog had a complete normalization of the urine stream, one dog had stable stranguria, and one dog was presented with a urethral obstruction secondary to progression of the TCC. On recheck ultrasound, one dog had a 38% diminution of the urethral mass diameter whereas the other two dogs had a mass stable in size. IRE balloon therapy seems to be a feasible and apparently safe minimally invasive novel therapy for the palliative treatment of TCC causing urethral obstruction. Further studies are needed to better characterize the safety, efficacy, and outcome of this therapy.

Neutrophils direct preexisting matrix to initiate repair in damaged tissues

Internal organs heal injuries with new connective tissue, but the cellular and molecular events of this process remain obscure. By tagging extracellular matrix around the mesothelium lining in mouse peritoneum, liver and cecum, here we show that preexisting matrix was transferred across organs into wounds in various injury models. Using proteomics, genetic lineage-tracing and selective injury in juxtaposed organs, we found that the tissue of origin for the transferred matrix likely dictated the scarring or regeneration of the healing tissue. Single-cell RNA sequencing and genetic and chemical screens indicated that the preexisting matrix was transferred by neutrophils dependent on the HSF-integrin AM/B2-kindlin3 cascade. Pharmacologic inhibition of this axis prevented matrix transfer and the formation of peritoneal adhesions. Matrix transfer was thus an early event of wound repair and provides a therapeutic window to dampen scaring across a range of conditions.

Determining tissue conductivity in tissue ablation by nanosecond pulsed electric fields

Nanosecond pulsed electric field (nsPEF) causes the permeabilization of the cell membrane and has been used to non-thermally treat cancerous tissues. As increased permeabilization in membranes were reported to be accompanied by impedance changes, the ablation effect of nsPEF on tissues can be monitored via the changes in tissue conductivity. In this study, effects of nsPEF on biological tissues were evaluated by determining the conductivities of potato and 4 T1-luc breast tumor tissues ex vivo from a murine model subjected to multiple 100-ns, 1-10 kV pulses. Using a four-needle electrode system with a calibrated electrode constant of 1.1 ± 0.1 cm, the conductivities of tissues was determined from both the network-analyzer measurement, before and after treatment, and voltage-current measurement in real-time. The conductivity of the potato tissue was measured for a frequency range of 0.1-3 MHz, and it increased with increasing pulse number and voltage amplitude. The conductivity of the tumor tissue was also observed to increase with pulse number and pulse voltage over a similar frequency range. In addition, the linear correlation between the ablation area in a treated potato tissue and the conductivity change in the tissue suggests that conductivity analysis of biological tissue under treatment could be a fast and sensitive approach to evaluate the effectiveness of a nsPEF treatment.

The Effect of Electrochemotherapy on Breast Cancer Cell Lines

Despite advances in treatment, breast cancer remains one of the leading causes of death, and obviously new approaches to the treatment are needed. Due to minimal side effects, unlike more aggressive forms of therapy such as chemotherapy and radiotherapy, the application of irreversible electroporation-electrochemotherapy represents a new modality in the treatment of cancer. Electrochemotherapy uses an electric field (375 V cm -1) to allow increased absorption of chemotherapeutic drugs selectively in tumor cells. Accordingly, the total dose of these agents can be significantly reduced and numerous side effects can be avoided in this way. The Real Time Cell Analysis-RTCA-xCELLigence system was used to monitor the cytotoxic effects of the treatment. The results confirmed the justification of the use of paclitaxel in chemotherapy and showed cytotoxic effects of paclitaxel which were time and dose-dependent in both cell lines. When paclitaxel was administered in combination with an electric field, in both cell lines, the results showed a greater cytotoxic effect compared to the same treatment without electrochemotherapy. MCF-7 cells are more sensitive to electrochemotherapy treatment with paclitaxel compared to MDA-MB-231. Electrochemotherapy using paclitaxel in MCF-7 cells had a 6.4-fold higher cytotoxicity compared to the treatment only with paclitaxel. The results obtained support the current knowledge of the benefits of electrochemotherapy. It has been shown that electrochemotherapy can significantly increase the effects of paclitaxel in the tested cell lines. In this way, a very high concentration of chemotherapeutics in the targeted tissue was achieved, which represents localized chemotherapy.

Irreversible Electroporation Enhanced by Radiofrequency Ablation: An In Vitro and Computational Study in a 3D Liver Tumor Model

In the present study, we used a computational and experimental study in a 3D liver tumor model (LTM) to explore the tumor ablation enhancement of irreversible electroporation (IRE) by pre-heating with radiofrequency ablation (RFA) and elucidate the mechanism whereby this enhancement occurs. Three ablation protocols, including IRE alone, RFA45 → IRE (with the pre-heating temperature of 45 °C), and RFA60 → IRE (with the pre-heating temperature of 60 °C) were investigated. Both the thermal conductivity and electrical conductivity of the 3D LTM were characterized with the change in the pre-heating temperature. The results showed, compared to IRE alone, a significant increase in the tumor ablation volume (19.59 [Formula: see text] 0.61 vs. 15.29 ± 0.61 mm³, p = 0.002 and 22.87 [Formula: see text] 0.35 vs. 15.29 ± 0.61 mm³, p < 0.001) was observed with both RFA45 → IRE and RFA60 → IRE, leading to a decrease in lethal electric filed strength (8 and 17%, correspondingly). The mechanism can be attributed to the change of cell microenvironment by pre-heating and/or a synergistic effect of RFA and IRE. The proposed enhancing method might contribute to the improvement of interventional oncology in the treatment of large tumors close to critical organs (e.g., large blood vessels and bile ducts).

Irreversible Electroporation for Renal Ablation Does Not Cause Significant Injury to Adjacent Ureter or Bowel in a Porcine Model

Objective: To evaluate the safety of irreversible electroporation (IRE) for renal ablation adjacent to the ureter or bowel. Materials and Methods: Six adult pigs each underwent bilateral IRE of the kidney. To simulate adjacence, the left proximal ureter and duodenum were secured onto the left and right kidney capsule, respectively. Two IRE probes were placed into the renal parenchyma and configured to bridge the ureter and bowel. Therapeutic IRE was delivered at 2000 V/cm for 70 pulses in both forward and reverse polarity. The animal was survived and euthanized at 1, 3, or 14 days. Histopathology was obtained for all potentially injured bowel and ureteral segments. Retrograde pyelogram (RPG) was performed on each left-sided ureter. Results: Histologic analysis of the ureter identified reactive changes at the level of the periureteral adipose tissue, which progressed from acute inflammation on day 1 to focal fibrosis by day 14. Urothelial mucosa and surrounding smooth muscle layers were unaffected at all time points. RPGs did not show any abnormalities in all specimens. Histologic analysis of the bowel demonstrated acute inflammation in the serosa and subserosal tissue on day 1. Three days after IRE, inflammation and crypt abscesses were focally present in the deep aspects of the bowel mucosa. Inflammation in the mucosal layer resolved 14 days after IRE. Conclusions: In a porcine model of renal IRE, no significant injury was apparent after intentional ablation adjacent to the ureter and bowel. IRE may be a safe alternative to thermal ablation for tumors near the ureter or bowel.

Investigation of safety for electrochemotherapy and irreversible electroporation ablation therapies in patients with cardiac pacemakers

BACKGROUND

The effectiveness of electrochemotherapy of tumors (ECT) and of irreversible electroporation ablation (IRE) depends on different mechanisms and delivery protocols. Both therapies exploit the phenomenon of electroporation of the cell membrane achieved by the exposure of the cells to a series of high-voltage electric pulses. Electroporation can be fine-tuned to be either reversible or irreversible, causing the cells to either survive the exposure (in ECT) or not (in IRE), respectively. For treatment of tissues located close to the heart (e.g., in the liver), the safety of electroporation-based therapies is ensured by synchronizing the electric pulses with the electrocardiogram. However, the use of ECT and IRE remains contraindicated for patients with implanted cardiac pacemakers if the treated tissues are located close to the heart or the pacemaker. In this study, two questions are addressed: can the electroporation pulses interfere with the pacemaker; and, can the metallic housing of the pacemaker modify the distribution of electric field in the tissue sufficiently to affect the effectiveness and safety of the therapy?

RESULTS

The electroporation pulses induced significant changes in the pacemaker ventricular pacing pulse only for the electroporation pulses delivered during the pacing pulse itself. No residual effects were observed on the pacing pulses following the electroporation pulses for all tested experimental conditions. The results of numerical modeling indicate that the presence of metal-encased pacemaker in immediate vicinity of the treatment zone should not impair the intended effectiveness of ECT or IRE even when the casing is in direct contact with one of the active electrodes. Nevertheless, the contact between the casing and the active electrode should be avoided due to significant tissue heating at the site of the other active electrode for the IRE protocol and may cause the pulse generator to fail to deliver the pulses due to excessive current draw.

CONCLUSIONS

The observed effects of electroporation pulses delivered in close vicinity of the pacemaker or its electrodes do not indicate adverse consequences for either the function of the pacemaker or the treatment outcome. These findings should contribute to making electroporation-based treatments accessible also to patients with implanted cardiac pacemakers.

Bioelectronic properties of DNA, protein, cells and their applications for diagnostic medical devices

From a couple of centuries ago, understanding physical properties of biological material, their interference with their natural host and their potential manipulation for employment as a conductor in medical devices, has gathered substantial interest in the field of bioelectronics. With the fast-emerging technologies for fabrication of diagnostic modalities, wearable biosensors and implantable devices, which electrical components are of essential importance, a need for developing novel conductors within such devices has evolved over the past decades. As the possibility of electron transport within small biological molecules, such as DNA and proteins, as well as larger elements such as cells was established, several discoveries of the modern charge characterization technologies were evolved. Development of Electrochemical Scanning Tunneling Microscopy and Nuclear Magnetic Resonance among many other techniques were of vital importance, following the discoveries made in sub-micron scales of biological material. This review covers the most recent understandings of electronic properties within different scale of biological material starting from nanometer range to millimeter-sized organs. We also discuss the state-of-the-art technology that's been made taking advantage of electronic properties of biological material for addressing diseases like Parkinson's Disease and Epilepsy.

Novel Ablation Therapy Using Endoscopic Irreversible Electroporation in the Bile Duct: A Pilot Animal Study

Background/Aims

Irreversible electroporation (IRE) is a relatively new ablation method. However, the application of IRE ablation in the treatment of biliary disease has not been attempted. A minimally invasive approach using endoscopic retrograde cholangiopancreatography (ERCP) can be a novel therapeutic modality for IRE ablation. In this study, we aimed to investigate the feasibility of endoscopic IRE for the biliary tract using an animal model.

Methods

A new catheter-type electrode was developed for endoscopic IRE ablation of the biliary tract. We performed ERCP and endoscopic IRE ablations in the normal common bile duct of Yorkshire pigs. The experimental setting of IRE was 500 V/cm (50 pulses, 100-µs length). The animals were sacrificed after 24 hr, and the ablated bile duct was examined.

Results

Well-demarcated focal color changes were observed on the mucosa of the common bile duct. The depth of change after IRE was confined to the mucosal and submucosal layers. Apoptotic changes in the bile duct were observed only around the IRE ablation area. Immunohistochemistry assay showed cell death in the bile duct along the electrode.

Conclusions

Endoscopic IRE ablation using ERCP was successfully performed in the common bile duct. It can be a potential option for the treatment of biliary tumors.

Electroporation technique for joint pain - Pilot feasibility study on TMD patients

Objective(s)

It is well appreciated that traditional analgesic delivery routes used to treat pain associated with temporomandibular disorder (TMD) often have harmful unintended side effects as a consequence of systemic distribution. Further, localized delivery of analgesic medication via intra‐articular injections involves a different set of issues limiting their clinical viability. As an option, transdermal analgesic delivery provides for prolonged pain relief and flexibility in dose administration, while limiting systemic exposure and minimizing adverse events. Incorporation of a novel electroporation technique may further increase transdermal drug penetration into synovial tissue/fluid and enhance pain reduction. The present feasibility study compares the effectiveness of an electroporation‐enhanced transdermal application of diclofenac sodium to a conventional intra‐articular injection of triamcinolone acetonide suspension (corticosteroids) to treat patients with TMD associated pain.

Methods

Pre‐ and post‐treatment maximal incisal mouth opening (MIO), pain visual analog scale (VAS) and surface electromyography (EMG) of 22 patients treated with electroporation‐enhanced diclofenac and 37 patients treated with corticosteroids injections were collected and analyzed.

Results

In general, patients treated with electroporation exhibited better results in terms of pain improvement (corrected p‐value = .01) compared to the standard treatment, but both methods were similarly effective for improvement of MIO (corrected p‐value = .71) and improvement of all EMG indices (corrected p‐values ≥ .05).

Conclusion

The enhancing effect of electroporation in transdermal delivery of diclofenac sodium was demonstrated by decreased pain, increase MIO and EMG improvement to normal values. Its analgesic and inflammatory results are comparable with standard treatment offered by corticosteroids.

Electrochemotherapy Using Doxorubicin and Nanosecond Electric Field Pulses: A Pilot in Vivo Study

Pulsed electric field (PEF) is frequently used for intertumoral drug delivery resulting in a well-known anticancer treatment-electrochemotherapy. However, electrochemotherapy is associated with microsecond range of electrical pulses, while nanosecond range electrochemotherapy is almost non-existent. In this work, we analyzed the feasibility of nanosecond range pulse bursts for successful doxorubicin-based electrochemotherapy in vivo. The conventional microsecond (1.4 kV/cm × 100 µs × 8) procedure was compared to the nanosecond (3.5 kV/cm × 800 ns × 250) non-thermal PEF-based treatment. As a model, Sp2/0 tumors were developed. Additionally, basic current and voltage measurements were performed to detect the characteristic conductivity-dependent patterns and to serve as an indicator of successful tumor permeabilization both in the nano and microsecond pulse range. It was shown that nano-electrochemotherapy can be the logical evolution of the currently established European Standard Operating Procedures for Electrochemotherapy (ESOPE) protocols, offering better energy control and equivalent treatment efficacy.

Spontaneous regression of ALK fusion protein-positive non-small cell lung carcinoma: a case report and review of the literature

BACKGROUND

ALK-rearrangement is observed in < 5% non-small cell lung cancer (NSCLC) cases and prior to the advent of oral tyrosine kinase inhibitors, the natural history of oncogenic NSCLC was typically poor. Literature relating to regression of treatment-naïve NSCLC is limited, and regression without treatment has not been noted in the ALK-rearranged sub-population.

CASE PRESENTATION

A 76 year old 'never smoker' female with an ALK-rearranged left upper lobe T2 N0 NSCLC experienced a stroke following elective DC cardioversion for new atrial fibrillation. Following a good recovery, updated imaging demonstrated complete regression of the left upper lobe lesion and a reduction of the previously documented mediastinal lymph node. Remaining atelectasis was non-avid on repeat PET-CT imaging, 8 months from the baseline PET-CT. When the patient developed new symptoms 6 months later a further PET-CT demonstrated FDG-avid local recurrence. She completed 55 Gy in 20 fractions but at 18 months post-radiotherapy there was radiological progression in the lungs with new pulmonary metastases and effusion and new bone metastases. Owing to poor performance status, she was not considered fit for targeted therapy and died 5 months later.

CONCLUSION

All reported cases of spontaneous regression in lung cancer have been collated within. Documented precipitants of spontaneous regression across tumour types include biopsy and immune reconstitution; stroke has not been reported previously. The favourable response achieved with radical radiotherapy alone in this unusual case of indolent oncogenic NSCLC reinforces the applicability of radiotherapy in locally advanced ALK-rearranged tumours, in cases not behaving aggressively. As a common embolic event affecting the neurological and pulmonary vasculature is less likely, an immune-mediated mechanism may underpin the phenomenon described in this patient, implying that hitherto unharnessed principles of immuno-oncology may have relevance in oncogenic NSCLC. Alternatively, high electrical voltage applied percutaneously adjacent to the tumour during cardioversion in this patient may have induced local tumour cell lethality.

Concepts and Capabilities of In-House Built Nanosecond Pulsed Electric Field (nsPEF) Generators for Electroporation: State of Art

Electroporation is a pulsed electric field triggered phenomenon of cell permeabilization, which is extensively used in biomedical and biotechnological context. There is a growing scientific demand for high-voltage and/or high-frequency pulse generators for electropermeabilization of cells (electroporators). In the scope of this article we have reviewed the basic topologies of nanosecond pulsed electric field (nsPEF) generators for electroporation and the parametric capabilities of various in-house built devices, which were introduced in the last two decades. Classification of more than 60 various nsPEF generators was performed and pulse forming characteristics (pulse shape, voltage, duration and repetition frequency) were listed and compared. Lastly, the trends in the development of the electroporation technology were discussed.

Electrotransfer of siRNA to Silence Enhanced Green Fluorescent Protein in Tumor Mediated by a High Intensity Pulsed Electromagnetic Field

The contactless high intensity pulsed electromagnetic field (HI-PEMF)-induced increase of cell membrane permeability is similar to conventional electroporation, with the important difference of inducing an electric field non-invasively by exposing a treated tissue to a time-varying magnetic field. Due to the limited number of studies in the field of electroporation induced by HI-PEMF, we designed experiments to explore the feasibility of such a contactless delivery technique for the gene electrotransfer of nucleic acids in tissues in vivo. By using HI-PEMF for gene electrotransfer, we silenced enhanced green fluorescent protein (EGFP) with siRNA molecules against EGFP in B16F10-EGFP tumors. Six days after the transfer, the fluorescent tumor area decreased by up to 39% as determined by fluorescence imaging in vivo. In addition, the silencing of EGFP to the same extent was confirmed at the mRNA and protein level. The results obtained in the in vivo mouse model demonstrate the potential use of HI-PEMF-induced cell permeabilization for gene therapy and DNA vaccination. Further studies are thus warranted to improve the equipment, optimize the protocols for gene transfer and the HI-PEMF parameters, and demonstrate the effects of HI-PEMF on a broader range of different normal and tumor tissues.

The interaction between irreversible electroporation therapy (IRE) and embolization material using a validated vegetal model: an experimental study

PURPOSE

Irreversible electroporation (IRE) is a nonthermal tumor ablation technique that induces cell apoptosis while preserving extracellular architecture. Surgical clips and embolic agents may lie adjacent to, or within, the target lesion. It is unknown to date if IRE causes degradation to the embolic agents or surgical clips that may have adverse effects to patients. We aimed to examine the effects of the IRE on the morphology of various embolic agents and the effects of these agents to the ablation field using a previously validated vegetal model.

METHODS

Metallic surgical clips and various metallic and nonmetallic embolic agents were inserted within the center of the tuber ablation field. Additionally, clips were inserted on the edge and outside the ablation field. One tuber was ablated as a control. Ablation settings were based on previous published experiments. Tubers were imaged with magnetic resonance imaging (MRI) 18-24 hours after ablation and the ablated field dimensions were measured. Nonmetallic embolic agents were examined microscopically by the pathologist.

RESULTS

Nonmetallic agents did not affect the ablation pattern. Metallic implants, however, caused arcing of the ablation margins. There was no macroscopic or microscopic degradation to the agents after IRE.

CONCLUSION

The ablation zone arced in the presence of surgical clips at the edge or outside the ablation margins; therefore, nearby critical structures may be susceptible to the effects of IRE. Furthermore, there was no physical degradation of the embolic agents or surgical clips, and this may have importance when considering IRE ablation of previously embolized lesions in vivo.

Interventional therapy in malignant conditions of the prostate

Interventional therapies are emerging modalities for the treatment of localized prostate cancer. Their aim is to reduce the morbidity associated with radical therapies (rT) by minimizing damage to non-cancerous tissue, with priority given to sparing key structures such as the neurovascular bundles, external sphincter, bladder neck, and rectum, while maintaining local cancer control. Interventional ablative technologies deliver energy in different ways to destroy cancer cells. The most widely investigated techniques are brachytherapy, external beam radiotherapy, cryotherapy, and high-intensity focused ultrasound. Although functional outcomes of focal therapies have been encouraging, with generally low rates of urinary incontinence and erectile dysfunction, robust medium- and long-term oncological outcomes are not available for all techniques. To date, major controversies in focal therapy concern appropriate patient selection, efficacy of focal therapies, as well as treatment paradigms based on the dominant index lesion hypothesis. This review articles discusses the current status of interventional therapies and the oncological and functional outcomes.

Hybrid analytical-numerical approach for investigation of differential effects in normal and cancer cells under electroporation

Electroporation has offered important biomedical applications in electrochemotherapy, tissue ablation and gene editing recently. Time and computation efficient analytical and numerical models should be developed to understand the differential effects of electroporation on normal and cancer cells. In this work, we present a hybrid analytical-numerical approach to investigate the behavior of normal and cancer cells under electroporation. We have compared the human breast cancer cell (MCF-7) and non-tumorigenic human breast cell (MCF-10A) under electroporation in terms of change in transmembrane voltage and pore formation on cell surface. The effects of electric pulse time, amplitude and membrane conductivity variation are analyzed in a systematic manner. To accelerate the calculation of transmembrane voltage, we have introduced a simple Multilayer Electric Potential Model (MEPM) which calculates the potential distribution across the cell analytically. The MEPM calculates electric potential distribution across a biological cell sandwiched between two semi-circular electrodes held at fixed potential, by solving the Laplace's equation over an equivalent planar, multilayer geometry. The MEPM model is then used in a Finite Element Method (FEM) based numerical model of electroporation. Transmembrane voltage and pore density for electroporated MCF-10A are estimated to be 1.31 V and 2.98 × 1013 m-2 respectively, and for MCF-7 the estimated values are 0.53 V and 1.93 × 1014 m-2, respectively. Our results suggest that under electroporation, the cancer cell's membrane get much more permeabilized than its counterpart normal cell even at small values of transmembrane voltage. This work provides a theoretical basis for further experimental exploration of electroporation process in cancer therapy, and serves as a design tool for performance optimization.

Antitumor Response and Immunomodulatory Effects of Sub-Microsecond Irreversible Electroporation and Its Combination with Calcium Electroporation

In this work, we have investigated the feasibility of sub-microsecond range irreversible electroporation (IRE) with and without calcium electroporation in vivo. As a model, BALB/C mice were used and bioluminescent SP2/0 myeloma tumor models were developed. Tumors were treated with two separate pulsed electric field (PEF) pulsing protocols PEF1: 12 kV/cm × 200 ns × 500 (0.006 J/pulse) and PEF2: 12 kV/cm × 500 ns × 500 (0.015 J/pulse), which were delivered with and without Ca²⁺ (168 mM) using parallel plate electrodes at a repetition frequency of 100 Hz. Both PEF1 and PEF2 treatments reduced tumor growth and prolonged the life span of the mice, however, the PEF2 protocol was more efficient. The delay in tumor renewal was the biggest when a combination of IRE with calcium electroporation was used, however, we did not obtain significant differences in the final mouse survival compared to PEF2 alone. Anti-tumor immune responses were also investigated after treatment with PEF2 and PEF2+Ca. In both cases the treated mice had enlarged spleens and increased spleen T cell numbers, lower percentages of suppressor cell subsets (conventional CD4⁺CD25⁺ Treg, CD4⁺CD25⁻DX5⁺ Tr1, CD8⁺DX5⁺, CD4⁺CD28⁻, CD8⁺CD28⁻), changed proportions of Tcm and Tef/Tem T cells in the spleen and increased amount of tumor cell specific antibodies in the sera. The treatment based on IRE was effective against primary tumors, destroyed the tumor microenvironment and induced an anti-tumor immune response, however, it was not sufficient for complete control of tumor metastasis.

Hydrogen gas therapy induced shrinkage of metastatic gallbladder cancer: A case report

BACKGROUND

We present the case of a 72-year-old female patient with gallbladder cancer (GBC) who developed in situ recurrence and liver metastases 9 mo after irreversible electroporation ablation and oral tegafur (a fluoropyrimidine derivative) chemotherapy, which failed to control the progression of the disease. The patient further developed metastases in the lymph nodes around the head of the pancreas. The patient had severe anemia, requiring weekly blood transfusions. The gallbladder tumor invaded the descending part of the duodenum, causing intestinal leakage and hepatic colonic adhesion.

CASE SUMMARY

The patient refused other treatments and began daily hydrogen inhalation therapy. After 1 mo of treatment, the gallbladder and liver tumors continued to progress, and intestinal obstruction occurred. After continuous hydrogen therapy and symptomatic treatments including gastrointestinal decompression and intravenous nutrition support, the intestinal obstruction was gradually relieved. Three months after hydrogen therapy, the metastases in the abdominal cavity gradually reduced in size, her anemia and hypoalbuminemia were corrected, lymphocyte and tumor marker levels returned to normal, and the patient was able to resume normal life.

CONCLUSION

This is the first report of an efficacy and safety study about hydrogen therapy in patient with metastatic GBC and a critical general condition, who has remained stable for more than 4 months.

Local treatment of oligometastatic disease: current role

The presence of distant metastases has long been a predictor of poor outcome in solid cancer. However, in an oncologic situation called oligometastatic disease (OMD), multiple studies have revealed a survival benefit with aggressive treatment of these metastases. Besides surgery and radiation therapy, local thermal therapies have developed into a treatment option for OMD. Most studies concerning local therapy of OMD are available for colorectal cancer, which is therefore the focus of this article. Furthermore, this review gives a basic overview of the most popular ablation techniques for treatment of OMD.

Prostate cancer "super-active surveillance" era opened by vascular targeted photodynamic therapy

The "super-active surveillance" concept denotes any active surveillance optimization that allows longer surveillance periods, with the main intention of avoiding overtreatment, by safely eliminating or postponing radical treatment. Super-active surveillance might add to the oncological control with minimal functional impact and similar quality of life compared to active surveillance, which has proved to be safe in well-selected patients. Vascular targeted photodynamic therapy has pioneering shown to significantly reduce the upgrade on subsequent biopsies, resulting in fewer cases converted to radical therapy, and any energy source can be applied to the super-active surveillance concept allowing more men to consider a tissue-preserving therapy for prostate cancer.

Theranostics in Interventional Oncology: Versatile Carriers for Diagnosis and Targeted Image-Guided Minimally Invasive Procedures

We are continuously progressing in our understanding of cancer and other diseases and learned how they can be heterogeneous among patients. Therefore, there is an increasing need for accurate characterization of diseases at the molecular level. In parallel, medical imaging and image-guided therapies are rapidly developing fields with new interventions and procedures entering constantly in clinical practice. Theranostics, a relatively new branch of medicine, refers to procedures combining diagnosis and treatment, often based on patient and disease-specific features or molecular markers. Interventional oncology which is at the convergence point of diagnosis and treatment employs several methods related to theranostics to provide minimally invasive procedures tailored to the patient characteristics. The aim is to develop more personalized procedures able to identify cancer cells, selectively reach and treat them, and to assess drug delivery and uptake in real-time in order to perform adjustments in the treatment being delivered based on obtained procedure feedback and ultimately predict response. Here, we review several interventional oncology procedures referring to the field of theranostics, and describe innovative methods that are under development as well as future directions in the field.

Low concentrations of acetic and formic acids enhance the inactivation of Staphylococcus aureus and Pseudomonas aeruginosa with pulsed electric fields

Background

Skin infections, particularly caused by drug-resistant pathogens, represent a clinical challenge due to being a frequent cause of morbidity and mortality. The objectives of this study were to examine if low concentrations of acetic and formic acids can increase sensitivity of Staphylococcus aureus and Pseudomonas aeruginosa to pulsed electric field (PEF) and thus, promote a fast and efficient treatment methodology for wound treatment.

Results

We have shown that the combination of PEF (10–30 kV/cm) with organic acids (0.1% formic and acetic acids) increased the bactericidal properties of treatment. The effect was apparent for both acids. The proposed methodology allowed to reduce the energy of electrical pulses and the inhibitory concentrations of acids, while still maintain high efficiency of bacteria eradication.

Conclusions

Application of weak organic acids as bactericidal agents has many advantages over antibiotics because they do not trigger development of drug-resistance in bacteria. The combination with PEF can make the treatment effective even against biofilms. The results of this study are particularly useful for the development of new methodologies for the treatment of extreme cases of wound infections when the chemical treatment is no longer effective or hinders wound healing.

Histopathological and Ultrastructural Changes after Electroporation in Pig Liver Using Parallel-Plate Electrodes and High-Performance Generator

Irreversible electroporation (IRE) has gained attention as a new non-thermal therapy for ablation with important benefits in terms of homogeneous treatment and fast recovery. In this study, a new concept of high voltage generator is used, enabling irreversible electroporation treatment in large tissue volume using parallel plates. Unlike currently available generators, the proposed versatile structure enables delivering high-voltage high-current pulses. To obtain homogeneous results, 3-cm parallel-plates electrodes have also been designed and implemented. IRE ablation was performed on six female pigs at 2000 V/cm electric field, and the results were analysed after sacrifice three hours, three days and seven days after ablation. Histopathological and ultrastructural studies, including transmission and scanning electron microscopy, were carried out. The developed high-voltage generator has proved to be effective for homogeneous IRE treatment using parallel plates. The destruction of the membrane of the hepatocytes and the alterations of the membranes of the cellular organelles seem incompatible with cell death by apoptosis. Although endothelial cells also die with electroporation, the maintenance of vascular scaffold allows repairing processes to begin from the third day after IRE as long as the blood flow has not been interrupted. This study has opened new direction for IRE using high performance generators and highlighted the importance of taking into account ultrastructural changes after IRE by using electron microscopy analysis.

Chemical Enhancement of Irreversible Electroporation: A Review and Future Suggestions

Irreversible electroporation has raised great interest in the past decade as a means of destroying cancers in a way that does not involve heat. Irreversible electroporation is a novel ablation technology that uses short high-voltage electrical pulses to enhance the permeability of tumor cell membranes and generate irreversible nano-sized structural defects or pores, thus leading to cell death. Irreversible electroporation has many advantages over thermal therapies due to its nonthermal mechanism: (1) reduced risk of injury to surrounding organs and (2) no "heat-sink" effect due to nearby blood vessels. However, so far, it has been difficult for irreversible electroporation to completely ablate large tumors (eg, >3 cm in diameter). In order to overcome this problem, many preclinical and clinical studies have been performed to improve the efficacy of IRE in the treatment of large size of tumors through a chemical perspective. Due to the distribution of electric field, irreversible electroporation region, reversible electroporation region, and intact region can be found in the treatment of irreversible electroporation. Thus, 2 types of chemical enhancements of irreversible electroporation were discussed in the article, such as the reversible electroporation region enhanced and the irreversible electroporation region enhanced. Specifically, the state-of-the-art results regarding the following approaches that have the potential to be used in the enhancement of irreversible electroporation were systematically reviewed in the article, including (1) combination with cytotoxic drugs, (2) calcium electroporation, (3) modification of cell membrane, and (4) modification of the tumor cell microenvironment. In the end, we concluded with 4 issues that should be addressed in the future for improving irreversible electroporation further in a chemical way.

Advanced physical techniques for gene delivery based on membrane perforation

Gene delivery as a promising and valid tool has been used for treating many serious diseases that conventional drug therapies cannot cure. Due to the advancement of physical technology and nanotechnology, advanced physical gene delivery methods such as electroporation, magnetoporation, sonoporation and optoporation have been extensively developed and are receiving increasing attention, which have the advantages of briefness and nontoxicity. This review introduces the technique detail of membrane perforation, with a brief discussion for future development, with special emphasis on nanoparticles mediated optoporation that have developed as an new alternative transfection technique in the last two decades. In particular, the advanced physical approaches development and new technology are highlighted, which intends to stimulate rapid advancement of perforation techniques, develop new delivery strategies and accelerate application of these techniques in clinic.

Nanosecond range electric pulse application as a non-viral gene delivery method: proof of concept

Current electrotransfection protocols are well-established for decades and, as a rule, employ long micro-millisecond range electric field pulses to facilitate DNA transfer while application of nanosecond range pulses is limited. The purpose of this paper is to show that the transfection using ultrashort pulses is possible by regulating the pulse repetition frequency. We have used 200 ns pulses (10-18 kV/cm) in bursts of ten with varied repetition frequency (1 Hz-1 MHz). The Chinese Hamster Ovary (CHO) cells were used as a cell model. Experiments were performed using green fluorescent protein (GFP) and luciferase (LUC) coding plasmids. Transfection expression levels were evaluated using flow cytometry or luminometer. It was shown that with the increase of frequency from 100 kHz to 1 MHz, the transfection expression levels increased up to 17% with minimal decrease in cell viability. The LUC coding plasmid was transferred more efficiently using high frequency bursts compared to single pulses of equivalent energy. The first proof of concept for frequency-controlled nanosecond electrotransfection was shown, which can find application as a new non-viral gene delivery method.

[Irreversible electroporation (IRE) : A minimally invasive therapeutic option in prostate cancer]

CLINICAL PROBLEM

Prostate cancer is one of the most common malignant diseases in older men. As such, screening and early detection are of crucial importance.

STANDARD TREATMENT

The standard management of prostate cancer includes radical prostatectomy, radiation therapy, or hormonal therapy. These standard therapies yield excellent oncologic results, but also produce significant side effects. In cases of low-risk prostate cancer, these therapies might result in over-treatment; for this reason, active surveillance has been introduced. However, acceptance of this strategy varies between patients.

TREATMENT INNOVATIONS

Irreversible electroporation is a novel non-thermal ablation technique for soft tissues. The ablation mechanism of irreversible electroporation has some theoretical advantages in the treatment of prostate cancer. It allows image-guided focal treatment of malignant prostate tissue and a potential sparing of adjacent structures, thereby theoretically resulting in a marked reduction in treatment-related side effects compared with standard management.

PRACTICAL RECOMMENDATIONS

Although irreversible electroporation is a promising ablation technique, it should only be used in the context of clinical trials to treat prostate cancer due to the current lack of solid evidence for this new technology.