Objective: To study the safety and efficacy of algorithmically controlled electroporation (ACE) against spontaneous equine melanoma. Methods: A custom temperature sensing coaxial electrode was paired ...with a high voltage pulse generation system with integrated temperature feedback controls. Computational modeling and ex vivo studies were conducted to evaluate the system's ability to achieve and maintain target temperatures. Twenty-five equine melanoma tumors were treated with a 2000V protocol consisting of a 2-5-2 waveform, 45ºC temperature set point, and integrated energized times of 0.005 s, 0.01 s, or 0.02 s (2500x, 5000x, and 10000x 2 μs pulses, respectively). Patients returned 20-50 days post treatment to determine the efficacy of the treatment. Results: ACE temperature control algorithms successfully achieved and maintained target temperatures in a diverse population of spontaneous tumors with significant variation in tissue impedance. All treatments were completed successfully without and without adverse events. Complete response rates greater than 93% were achieved in all treatment groups. Conclusion: ACE is a safe and effective treatment for spontaneous equine melanoma. The temperature control algorithm enabled rapid delivery of electroporation treatments without prior knowledge of tissue electrical or thermal properties and could adjust to real time changes in tissue properties. Significance: Real time temperature control in electroporation procedures enables treatments near critical structures where thermal damage is contraindicated. Unlike standard approaches, ACE protocols do not require extensive pretreatment planning or knowledge of tissue properties to determine an optimal energy delivery rate and they can account for changes in tissue state (e.g. perfusion) in real time to simultaneously minimize treatment time and potential for thermal damage.
Non-thermal irreversible electroporation (NTIRE) is a biophysical phenomenon in which certain electric fields delivered across the cell membrane in tissue, cause cell death, without affecting the ...extracellular matrix. “Minimally invasive regenerative surgery” is a new medical modality for treatment of end-stage organ or tissue failure in which exogenous cells are implanted in a decellularized niche in tissue, formed by the delivery of NTIRE electric fields across a targeted volume of tissue. We anticipate that the success of the procedure will depend on the time of implantation relative to the application of NTIRE. This study was performed to elucidate the histological and molecular events that occur within 24 h after NTIRE, in the context of optimal criteria for the time of implantation. To this end, we examined the histology of NTIRE treated rat liver with H&E, Masson trichrome and TUNEL staining. Western blot was used to examine pro and cleaved caspase-3 (marker for apoptosis), pro and cleaved caspase-1 and gasdermin D (markers for pyroptosis), and RIP3 and MLKL (markers for necroptosis). The key findings are that, complete hepatocytes disintegration within an intact extracellular matrix is seen at 6 h and, new hepatocytes are seen in the treated region at 24 h, after NTIRE. There is no evidence of apoptotic cell death from NTIRE, contrary to commonly made claims in the NTIRE literature. However, molecular pathways of pyroptosis and necroptosis, programed necrosis associated with inflammation, are activated at 6 h after NTIRE and are not evident at 24 h after NTIRE. These are fundamental new findings of basic value to the field of NTIRE in all its applications. Taken together the results suggest the hypothesis that an optimal time for implantation is about 24 h after NTIRE. Future studies in which exogenous cells are implanted at different times after NTIRE are required to examine this hypothesis.
•Hepatocytes completely disintegrate within 6 h after NTIRE, TUNEL stain is seen as a diffuse stain throughout the treated volume 6 h after NTIRE.•The extracellular matrix in the treated volume is intact after NTIRE.•Hepatocytes, normal and bi-nucleated, are seen in the treated volume, 24 h after NTIRE.•Cleaved caspase-3 is actually downregulated after NTIRE.•Cleaved caspase-1, gasdermin D, RIP3 and MLKL are upregulated 6 h, and downregulated 24 h after NTIRE.
The blood-brain barrier remains a main hurdle to drug delivery to the brain. The prognosis of glioblastoma remains grim despite current multimodal medical management. We review neurosurgical ...technologies that disrupt the blood-brain barrier (BBB). We will review superselective intra-arterial mannitol infusion, focused ultrasound, laser interstitial thermotherapy, and non-thermal irreversible electroporation (NTIRE). These technologies can lead to transient BBB and blood-brain tumor barrier disruption and allow for the potential of more effective local drug delivery. Animal studies and preliminary clinical trials show promise for achieving this goal.
Pancreatic islet transplantation via infusion through the portal vein, has become an established clinical treatment for patients with type 1 diabetes. Because the engraftment efficiency is low, new ...approaches for pancreatic islets implantation are sought. The goal of this study is to explore the possibility that a non-thermal irreversible electroporation (NTIRE) decellularized matrix in the liver could be used as an engraftment site for pancreatic islets.
Pancreatic islets or saline controls were injected at sites pre-treated with NTIRE in the livers of 7 rats, 16 hours after NTIRE treatment. Seven days after the NTIRE treatment, islet graft function was assessed by detecting insulin and glucagon in the liver with immunohistochemistry.
Pancreatic islets implanted into a NTIRE-treated volume of liver became incorporated into the liver parenchyma and produced insulin and glucagon in 2 of the 7 rat livers. Potential reasons for the failure to observe pancreatic islets in the remaining 5/7 rats may include local inflammatory reaction, graft rejection, low numbers of starting islets, timing of implantation.
This study shows that pancreatic islets can become incorporated and function in an NTIRE-generated extracellular matrix niche, albeit the success rate is low. Advances in the field could be achieved by developing a better understanding of the mechanisms of failure and ways to combat these mechanisms.
Electroporation is a phenomenon used in the treatment of tumors by electrochemotherapy, non-thermal ablation with irreversible electroporation, and gene therapy. When treating patients, either ...predefined or variable electrode geometry is used. Optimal pulse parameters are predetermined for predefined electrode geometry, while they must be calculated for each specific case for variable electrode geometry. The position and number of electrodes are also determined for each patient. It is currently assumed that above a certain experimentally determined value of electric field, all cells are permeabilized/destroyed and under it they are unaffected. In this paper, mathematical models of survival in which the probability of cell death is continuously distributed from 0 to 100 % are proposed and evaluated. Experiments were performed on cell suspensions using electrical parameters similar to standard electrochemotherapy and irreversible electroporation parameters. The proportion of surviving cells was determined using clonogenic assay for assessing the ability of a cell to grow into a colony. Various mathematical models (first-order kinetics, Hülsheger, Peleg-Fermi, Weibull, logistic, adapted Gompertz, Geeraerd) were fitted to experimental data using a non-linear least-squares method. The fit was evaluated by calculating goodness of fit and by observing the trend of values of models’ parameters. The most appropriate models of cell survival as a function of treatment time were the adapted Gompertz and the Geeraerd models and, as a function of the electric field, the logistic, adapted Gompertz and Peleg-Fermi models. The next steps to be performed are validation of the most appropriate models on tissues and determination of the models’ predictive power.
Electrochemotherapy (ECT) and Irreversible Electroporation are recent non-thermal techniques employed for the treatment of tumors. These therapies are based on the opening of pores in the cell ...membrane during application of sufficiently high electric fields. Over the past two decades, clinical trials have validated these therapies in humans. Moreover, ECT has been successfully applied in several species in veterinary clinics. As the therapy depends on the electric field distribution, numerical models and in vitro experiments have an important role in better understanding electric field distribution in biological tissues, especially in anatomically and physiologically complex structures. The potato tuber has emerged as an option for testing the effectiveness of the new electrodes. Potatoes present advantages for several reasons: they are compatible with the 3Rs’ concept for animal testing; they are simple to handle; and their electroporated areas become dark after 6–12 h. In this work, we simulated four numerical models from the literature and compared them to in vitro experiments. Our aim was to determine the model that best describes the observable affected area. This is an important point because the models were developed to properly describe tissue variation in electrical conductivity during electroporation, not to determine how electroporation is manifested macroscopically in potato tissue. The area measured with the Miklavčič–Ivorra–Suárez model was in closest agreement to the experiments; however, none of the models exactly represent our in vitro results.
Purpose
The nonthermal irreversible electroporation (NTIRE) is a novel potential ablation modality for renal masses. The aim of this study was the first evaluation of NTIRE’s effects on the renal ...urine-collecting system using intravenous urography (IVU) and urinary cytology in addition to histology and magnetic resonance imaging (MRI).
Methods
Eight percutaneous NTIRE ablations of the renal parenchyma, including the calyxes or pelvis, were performed in three male swine. MRI, IVU, histology, and urinary cytology follow-ups were performed within the first 28 days after treatment.
Results
MRI and histological analysis demonstrated a localized necrosis 7 days and a localized scarification of the renal parenchyma with complete destruction 28 days after NTIRE. The urine-collecting system was preserved and showed urothelial regeneration. IVU and MRI showed an unaltered normal morphology of the renal calyxes, pelvis, and ureter. A new urinary cytology phenomenon featured a temporary degeneration by individual vacuolization of detached transitional epithelium cells within the first 3 days after NTIRE.
Conclusions
This first urographical, urine-cytological, and MRI evaluation after porcine kidney NTIRE shows multifocal parenchyma destruction while protecting the involved urine-collecting system with regenerated urothelial tissue. NTIRE could be used as a targeted ablation method of centrally located renal masses.
Introduction. Electroporation-based treatments rely on increasing the permeability of the cell membrane by high voltage electric pulses delivered to tissue via electrodes. To ensure that the whole ...tumor is covered by the sufficiently high electric field, accurate numerical models are built based on individual patient geometry. For the purpose of reconstruction of hepatic vessels from MRI images we searched for an optimal segmentation method that would meet the following initial criteria: identify major hepatic vessels, be robust and work with minimal user input.
Materials and methods. We tested the approaches based on vessel enhancement filtering, thresholding, and their combination in local thresholding. The methods were evaluated on a phantom and clinical data. Results.
Results show that thresholding based on variance minimization provides less error than the one based on entropy maximization. Best results were achieved by performing local thresholding of the original de-biased image in the regions of interest which were determined through previous vessel-enhancement filtering. In evaluation on clinical cases the proposed method scored in average sensitivity of 93.68%, average symmetric surface distance of 0.89 mm and Hausdorff distance of 4.04 mm.
Conclusions. The proposed method to segment hepatic vessels from MRI images based on local thresholding meets all the initial criteria set at the beginning of the study and necessary to be used in treatment planning of electroporation- based treatments: it identifies the major vessels, provides results with consistent accuracy and works completely automatically. Whether the achieved accuracy is acceptable or not for treatment planning models remains to be verified through numerical modeling of effects of the segmentation error on the distribution of the electric field.
Electroporation is a physical phenomenon in which pulsed electric fields applied across a cell produce transient (reversible) or permanent (irreversible) permeabilization of the cell membrane. ...Irreversible electroporation is an important method of sterilization in the food industry and it is becoming an important minimally invasive tissue ablation technique in medicine. Motivated by recent observations of apoptosis like marker stains in irreversibly electroporated cells we performed a study on the effects of electroporation type electric pulses on the integrity of naked DNA in solution. Using gel electrophoresis analyses we show that pulses of the irreversible electroporation type have the ability to affect the naked DNA in solution. It is found that some electric parameters that lead to cell death by irreversible electroporation also cause changes in the naked DNA exposed to the same procedure. Our analysis tentatively suggests that some electroporation type electric pulses cause nicks in the DNA molecule. Therefore, it is possible that the mechanisms of cell death in irreversible electroporation also include damages to the DNA. However, this work did not investigate the possible effects of electroporation induced electrode corrosion byproducts, such as Al3+ ions on DNA integrity; which should be also studied in the future. In general, since electroporation phenomena based applications are widely used in medicine and biotechnology, the current study suggests that further research into the effects of electroporation type electric pulses on the DNA are warranted.
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