Breast tissue ablation with irreversible electroporation in rabbits: A safety and feasibility study

Effects of electroporation on Acanthamoeba Polyphaga

BACKGROUND

Species of the genus Acanthamoeba spp. are ubiquitous and can cause Acanthamoeba keratitis (AK), a serious corneal infection. Due to the toxicity and ineffectiveness of currently available prolonged therapies, we investigated electroceutical treatment aimed at facilitating the permeation of molecules through the membrane of cysts and trophozoites, which allows for faster elimination of the parasite.

METHODS

Cysts and trophozoites of Acanthamoeba polyphaga (ATCC® 30461TM) were exposed in vitro to an electric field with intensities of 2,000 volts and 2,500 volts. Viability after electroporation was assessed by the exclusion method with 0.4% trypan blue dye, while permeabilization was assessed by fluorescence microscopy using propidium iodide (PI), since both are impermeable to the membrane of viable and intact cells. The images were acquired on a Nikon Eclipse TI-U microscope and analyzed using ImageJ software.

RESULTS

With regard to viability, 40% of the trophozoites electroporated at 2,000 V and 42% of those electroporated at 2,500 V were lost, while for cysts the loss was 13% and 16% respectively. Considering permeabilization, 55% of trophozoites and cysts were permeabilized at 2,000 V (p ≤ 0.05); and 59% at 2,500 V for both (p ≤ 0.05). Values of p < 0.05 were considered statistically significant.

CONCLUSION

The voltages tested were effective for both cysts and trophozoites, since the percentages of permeabilization were close, with no statistical significance between them, only with the control groups. These results suggest the possibility that an electroceutical treatment could be applied as a complement to the standard treatment for AK.

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

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

Percutaneous Management of Breast Cancer: a Systematic Review

PURPOSE OF REVIEW

Surgical treatment of breast cancer is becoming increasingly more minimally invasive. We review the development status of percutaneous management for primary breast cancer and the evidence relating to tumor size as a fundamental determinant of treatment clinical outcome.

RECENT FINDINGS

It is safe and feasible for percutaneous management to treat breast cancer. For tumor size ≤ 2 cm, percutaneous management is a promising alternative modality. For tumor size ≤ 3 cm, it is controversial whether percutaneous management can achieve similar effects to surgery, especially its long-term effects. For tumor size > 3 cm, it is still in the initial exploration stage and showed the potential in the treatment of unresectable cancer by benefitting the local control of primary cancer. Percutaneous management of breast cancer is a valuable method for breast cancer treatment in selected patients. However, it will be necessary to provide the high level of evidence for widespread clinical application.

Image-guided Microinvasive Percutaneous Treatment of Breast Lesions: Where Do We Stand?

Treatment of breast lesions has evolved toward the use of less-invasive or minimally invasive techniques. Minimally invasive treatments destroy focal groups of cells without surgery; hence, less anesthesia is required, better cosmetic outcomes are achieved because of minimal (if any) scarring, and recovery times are shorter. These techniques include cryoablation, radiofrequency ablation, microwave ablation, high-intensity focused US, laser therapy, vacuum-assisted excision, and irreversible electroporation. Each modality involves the use of different mechanisms and requires specific considerations for application. To date, only cryoablation and vacuum-assisted excision have received U.S. Food and Drug Administration approval for treatment of fibroadenomas and have been implemented as part of the treatment algorithm by the American Society of Breast Surgeons. Several clinical studies on this topic have been performed on outcomes in patients with breast cancer who were treated with these techniques. The results are promising, with more data for radiofrequency ablation and cryoablation available than for other minimally invasive methods for treatment of early-stage breast cancer. Clinical decisions should be made on a case-by-case basis, according to the availability of the technique. MRI is the most effective imaging modality for postprocedural follow-up, with the pattern of enhancement differentiating residual or recurrent disease from postprocedural changes. ^©RSNA, 2021.

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.

Characterization of irreversible electroporation on the stomach: A feasibility study in rats

Irreversible electroporation (IRE) is a newly developed non-thermal ablative therapy. During the IRE procedure, the permeability of the cell membrane is irreversibly changed by application of high-energy pulses across the tissue. This induces the breakdown of cell homeostasis, and thereby cell death. Here, we present an in vivo study to demonstrate IRE ablation of gastric tissue and characterize the changes that occur with time therein. No significant complications were observed in the test rats during the experiment. The electroporated tissues exhibited apoptosis at 10, 24 and 48 h after IRE ablation. The apoptosis peaked at 10 h after IRE and then declined, suggesting that the ablated tissue rapidly recovered owing to intense metabolic activity. In addition, the electroporated tissues exhibited morphological changes such as pyknosis and karyorrhexis, while histological analysis showed that the blood vessels were preserved. Interestingly, electroporation greatly affected the mucosa and muscularis propria, but not the submucosa and serosa. This study suggests that IRE could potentially be used as a minimally invasive treatment for early gastric cancer that does not exhibit lymph node metastasis or dysplasia.

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.

Computational Feasibility Analysis of Electrochemotherapy With Novel Needle-Electrode Arrays for the Treatment of Invasive Breast Ductal Carcinoma

Breast cancer represents a rising problem concerning public health worldwide. Current efforts are aimed to the development of new minimally invasive and conservative treatment procedures for this disease. A treatment approach for invasive breast ductal carcinoma could be based on electroporation. Hence, in order to determine the effectiveness of electrochemotherapy in the treatment of this disease, 12 electrode models were investigated on realistic patient-specific computational breast models of 3 patients diagnosed by Digital Breast Tomosynthesis imaging. The electrode models exhibit 4, 5, and 6 needles arranged in 4 geometric configurations (delta, diamond, and star) and 3 different needle spacing resulting in a total of 12 needle-electrode arrays. Electric field distribution in the tumors and a surrounding safety margin of 1 cm around the tumor edge is computed using the finite element method. Efficiency of the electrode arrays was determined hierarchically based on (1) percentage of tumor volume reversibly electroporated, (2) percentage of tumor volume irreversibly electroporated, (3) percentage of treated safety margin volume, (4) minimal invasiveness, that is, minimal number of electrodes used, (5) minimal activated electrode pairs, and (6) minimal electric current. Results show that 3 electrode arrays (4 needle-delta, 5 needle-diamond, and 6 needle-star) with fixed-geometry configuration could be used in the treatment with electrochemotherapy of invasive breast ductal carcinomas ranging from 1 to 5 cm³ along with a surrounding safety margin of 1 cm.