Irreversible electroporation promotes a pro-inflammatory tumor microenvironment and anti-tumor immunity in a mouse pancreatic cancer model.

Pancreatic cancer is a significant cause of cancer-related mortality and often presents with limited treatment options. Pancreatic tumors are also notorious for their immunosuppressive microenvironment. Irreversible electroporation (IRE) is a non-thermal tumor ablation modality that employs high-voltage microsecond pulses to transiently permeabilize cell membranes, ultimately inducing cell death. However, the understanding of IRE's impact beyond the initiation of focal cell death in tumor tissue remains limited. In this study, we demonstrate that IRE triggers a unique mix of cell death pathways and orchestrates a shift in the local tumor microenvironment driven, in part, by reducing the myeloid-derived suppressor cell (MDSC) and regulatory T cell populations and increasing cytotoxic T lymphocytes and neutrophils. We further show that IRE drives induce cell cycle arrest at the G0/G1 phase in vitro and promote inflammatory cell death pathways consistent with pyroptosis and programmed necrosis in vivo. IRE-treated mice exhibited a substantial extension in progression-free survival. However, within a span of 14 days, the tumor immune cell populations reverted to their pre-treatment composition, which resulted in an attenuation of the systemic immune response targeting contralateral tumors and ultimately resulting in tumor regrowth. Mechanistically, we show that IRE augments IFN- Î³ signaling, resulting in the up-regulation of the PD-L1 checkpoint in pancreatic cancer cells. Together, these findings shed light on potential mechanisms of tumor regrowth following IRE treatment and offer insights into co-therapeutic targets to improve treatment strategies.

Feasibility of linking universal child and family healthcare and financial counselling: findings from the Australian Healthier Wealthier Families (HWF) mixed-methods study.

OBJECTIVES: 'Healthier Wealthier Families' (HWF) seeks to reduce financial hardship in the early years by embedding a referral pathway between Australia's universal child and family health (CFH) services and financial counselling. This pilot study investigated the feasibility and short-term impacts of HWF, adapted from a successful Scottish initiative. METHODS: Setting: CFH services in five sites across two states, coinciding with the COVID-19 pandemic. PARTICIPANTS: Caregivers of children aged 0-5 years experiencing financial hardship (study-designed screen). DESIGN: Mixed methods. With limited progress using a randomised trial (RCT) design in sites 1-3 (March 2020-November 2021), qualitative interviews with service providers identified implementation barriers including stigma, lack of knowledge of financial counselling, low financial literacy, research burden and pandemic disruption. This informed a simplified RCT protocol (site 4) and direct referral model (no randomisation, pre-post evaluation, site 5) (June 2021-May 2022). INTERVENTION: financial counselling; comparator: usual care (sites 1-4). Feasibility measures: proportions of caregivers screened, enrolled, followed up and who accessed financial counselling. Impact measures: finances (quantitative) and other (qualitative) to 6 months post-enrolment. RESULTS: 355/434 caregivers completed the screen (60%-100% across sites). In RCT sites (1-4), 79/365 (19%-41%) reported hardship but less than one-quarter enrolled. In site 5, n=66/69 (96%) caregivers reported hardship and 44/66 (67%) engaged with financial counselling; common issues were utility debts (73%), and obtaining entitlements (43%) or material aid/emergency relief (27%). Per family, financial counselling increased income from government entitlements by an average $A6504 annually plus $A784 from concessions, grants, brokerage and debt waivers. Caregivers described benefits (qualitative) including reduced stress, practical help, increased knowledge and empowerment. CONCLUSIONS: Financial hardship screening via CFH was acceptable to caregivers, direct referral was feasible, but individual randomisation was infeasible. Larger-scale implementation will require careful, staged adaptations where CFH populations and the intervention are well matched and low burden evaluation. TRIAL REGISTRATION NUMBER: ACTRN12620000154909.

Short-course antibiotic therapy for pneumonia in the neonatal intensive care unit.

OBJECTIVE: To determine the adherence and safety outcomes of a 5-day antibiotic course with a "time-out" for treatment of "blood culture-negative" pneumonia in the NICU. STUDY DESIGN: Prospective surveillance of all infants diagnosed with pneumonia at 7 NICUs from 8/2020-12/2021. Safety outcomes were defined a priori by re-initiation of antibiotic therapy within 14 days after discontinuation and overall and sepsis-related mortality. RESULTS: 128 infants were diagnosed with 136 episodes of pneumonia; 88% (n = 119) were treated with 5 days of definitive antibiotic therapy. Antibiotics were restarted within 14 days in 22 (16%) of the 136 pneumonia episodes. However, only 3 (3%) of the 119 episodes of pneumonia treated for 5 days had antibiotics restarted for pneumonia. Mortality was 5% (7/128); 5 of the 7 deaths were assessed as sepsis-related. CONCLUSION: Adherence to the 5-day definitive antibiotic treatment for "culture-negative" pneumonia was high and the intervention seemed safe.

Short-course empiric antibiotic therapy for possible early-onset sepsis in the NICU.

OBJECTIVE: On 2/2019, the Neonatal Antimicrobial Stewardship Program at Nationwide Children's Hospital recommended reducing empirical antibiotic therapy for early-onset sepsis (EOS) from 48 to 24 hours with a TIME-OUT. We describe our experience with this guideline and assess its safety. METHODS: Retrospective review of newborns evaluated for possible EOS at 6 NICUs from 12/2018-7/2019. Safety endpoints were re-initiation of antibiotics within 7 days after discontinuation of the initial course, positive bacterial blood or cerebrospinal fluid culture in the 7 days after antibiotic discontinuation, and overall and sepsis-related mortality. RESULT: Among 414 newborns evaluated for EOS, 196 (47%) received a 24 hour rule-out sepsis antibiotic course while 218 (53%) were managed with a 48 hour course. The 24-hour rule-out group were less likely to have antibiotics re-initiated and did not differ in the other predefined safety endpoints. CONCLUSION: Antibiotic therapy for suspected EOS may be discontinued safely within 24 hours.

Opioid prescribing in general practice: an Australian cross-sectional survey.

BACKGROUND: Prescribed opioid doses > 100 mg oral morphine equivalent (OME) and/or co-prescribing of sedating psychoactive medications increase the risk of unintentional fatal overdose. We describe general practice encounters where opioids are prescribed and examine high-risk opioid prescribing. METHODS: The 2006-2016 BEACH study data, a rolling national cross-sectional survey of randomly selected GPs, was analysed. RESULTS: Opioid prescribing increased 2006-2007 to 2015-2016, however, this plateaued across the latter half-decade. From 2012-2016 3,897 GPs recorded 389,700 encounters and at least one opioid was prescribed at 5.2%. Opioid encounters more likely involved males, those 45-64 years, concession card holders and the socioeconomically disadvantaged. GPs more likely to prescribe opioids were 55 years or older, male, Australian graduates, and in regional and remote areas. The most common problems managed with opioids involved chronic non-cancer pain. One-in-ten opioid prescribing episodes involved high-risk doses and 11% involved co-prescription of sedating psychoactive medications. Over one-third of GPs provided other (non-pharmacological) interventions at encounters with opioid prescriptions. CONCLUSIONS: Only 5% of GP encounters involved an opioid prescription. Of concern, were: prescribing for chronic non-cancer pain, potentially high-risk opioid encounters where > 100 OME daily dose was prescribed, and/or there was co-prescription of sedating psychoactive medication. However, approximately one-in-three opioid prescribing encounters involved non-pharmacological interventions.

Diagnosing a nocturnal eating disorder in an average-weight man.

A middle-aged man of average weight presented to the sleep medicine clinic for multiple episodes of nocturnal eating during night-time awakenings for the past several months. His symptoms were more characteristic of night eating syndrome rather than sleep-related eating disorder because of his recollection of the eating episodes and intake of edible substances during these episodes. He was treated with a low dose of sertraline with an initial improvement of symptoms followed by a relapse that was controlled with an increased dose. A year after initiation of therapy, his symptoms have resolved.

Navigating Pregnancy for Employees in Civilian Rotary-Wing Aeromedicine.

INTRODUCTION: Women of child-bearing age make up an ever-increasing element of the aeromedical workforce in Australia and the UK. However, policy relating to the management of risk for pregnant employees in this sector is often missing or inadequate, with many women facing detrimental impacts on their career progression and financial well-being. For women who choose to continue flying, there is a lack of transparent guidance about the risks of flying within a helicopter in an aeromedical role. While grounding pregnant employees removes some risks, it is at the cost of autonomy and brings other adverse effects for the employee and employer. Updated reflections on this important topic will empower the audience to make informed discussions around pregnancy in aeromedical roles.TOPIC: Applying principles from literature surrounding commercial, military, and medical aviation, the risks to pregnant employees and the fetus are reviewed. These risks are complex and dynamic depending on gestation and underlying medical problems; thus, individualization of risk management is of key importance. In low-risk pregnancies, incapacitation risk is below the usual threshold adopted for safety-sensitive aviation activities. Based on available evidence we have quantified risks where possible and provide guidance on the relevant factors to consider in creating a holistic risk-management framework. The greatest unknown surrounds the risk from vibration, noise, and winching. These are reviewed and suggestions given for discussing this risk. We also highlight the need for policy providing acceptable nonflying options to remove the pressure to continue flying in pregnancy.APPLICATION: Based on a literature review we have generated a framework for understanding and assessing risk relating to pregnant employees in the aeromedical sector. This is intended for use by aeromedical organizations, pregnant employees, and their treating medical practitioners to provide rational and sensible policy and guidance.Storey HM, Austin J, Davies-White NL, Ransley DG, Hodkinson PD. Navigating pregnancy for employees in civilian rotary-wing aeromedicine. Aerosp Med Hum Perform. 2022; 93(12):866-876.

Properties of tissue within prostate tumors and treatment planning implications for ablation therapies.

Irreversible electroporation (IRE) is a promising alternative therapy for the local treatment of prostate tumors. The procedure involves the direct insertion of needle electrodes into the target zone, and subsequent delivery of short but high-voltage pulses. Successful outcomes rely on adequate exposure of the tumor to a threshold electrical field. To aid in predicting this exposure, computational models have been developed, yet often do not incorporate the appropriate tissue-specific properties. This work aims to quantify electrical conductivity behavior during IRE for three types of tissue present in the target area of a prostate cancer ablation: the tumor tissue itself, the surrounding healthy tissue, and potential areas of necrosis within the tumor. Animal tissues were used as a stand-in for primary samples. The patient-derived prostate tumor tissue showed very similar responses to healthy porcine prostate tissue. An examination of necrotic tissue inside the tumors revealed a large difference, however, and a computational model showed that a necrotic core with differing electrical properties can cause unexpected inhomogeneities within the treatment region.

New Australian guidelines for the treatment of alcohol problems: an overview of recommendations.

OF RECOMMENDATIONS AND LEVELS OF EVIDENCE: Chapter 2: Screening and assessment for unhealthy alcohol use Screening Screening for unhealthy alcohol use and appropriate interventions should be implemented in general practice (Level A), hospitals (Level B), emergency departments and community health and welfare settings (Level C). Quantity-frequency measures can detect consumption that exceeds levels in the current Australian guidelines (Level B). The Alcohol Use Disorders Identification Test (AUDIT) is the most effective screening tool and is recommended for use in primary care and hospital settings. For screening in the general community, the AUDIT-C is a suitable alternative (Level A). Indirect biological markers should be used as an adjunct to screening (Level A), and direct measures of alcohol in breath and/or blood can be useful markers of recent use (Level B). Assessment Assessment should include evaluation of alcohol use and its effects, physical examination, clinical investigations and collateral history taking (Level C). Assessment for alcohol-related physical problems, mental health problems and social support should be undertaken routinely (GPP). Where there are concerns regarding the safety of the patient or others, specialist consultation is recommended (Level C). Assessment should lead to a clear, mutually acceptable treatment plan which specifies interventions to meet the patient's needs (Level D). Sustained abstinence is the optimal outcome for most patients with alcohol dependence (Level C). Chapter 3: Caring for and managing patients with alcohol problems: interventions, treatments, relapse prevention, aftercare, and long term follow-up Brief interventions Brief motivational interviewing interventions are more effective than no treatment for people who consume alcohol at risky levels (Level A). Their effectiveness compared with standard care or alternative psychosocial interventions varies by treatment setting. They are most effective in primary care settings (Level A). Psychosocial interventions Cognitive behaviour therapy should be a first-line psychosocial intervention for alcohol dependence. Its clinical benefit is enhanced when it is combined with pharmacotherapy for alcohol dependence or an additional psychosocial intervention (eg, motivational interviewing) (Level A). Motivational interviewing is effective in the short term and in patients with less severe alcohol dependence (Level A). Residential rehabilitation may be of benefit to patients who have moderate-to-severe alcohol dependence and require a structured residential treatment setting (Level D). Alcohol withdrawal management Most cases of withdrawal can be managed in an ambulatory setting with appropriate support (Level B). Tapering diazepam regimens (Level A) with daily staged supply from a pharmacy or clinic are recommended (GPP). Pharmacotherapies for alcohol dependence Acamprosate is recommended to help maintain abstinence from alcohol (Level A). Naltrexone is recommended for prevention of relapse to heavy drinking (Level A). Disulfiram is only recommended in close supervision settings where patients are motivated for abstinence (Level A). Some evidence for off-label therapies baclofen and topiramate exists, but their side effect profiles are complex and neither should be a first-line medication (Level B). Peer support programs Peer-led support programs such as Alcoholics Anonymous and SMART Recovery are effective at maintaining abstinence or reductions in drinking (Level A). Relapse prevention, aftercare and long-term follow-up Return to problematic drinking is common and aftercare should focus on addressing factors that contribute to relapse (GPP). A harm-minimisation approach should be considered for patients who are unable to reduce their drinking (GPP). Chapter 4: Providing appropriate treatment and care to people with alcohol problems: a summary for key specific populations Gender-specific issues Screen women and men for domestic abuse (Level C). Consider child protection assessments for caregivers with alcohol use disorder (GPP). Explore contraceptive options with women of reproductive age who regularly consume alcohol (Level B). Pregnant and breastfeeding women Advise pregnant and breastfeeding women that there is no safe level of alcohol consumption (Level B). Pregnant women who are alcohol dependent should be admitted to hospital for treatment in an appropriate maternity unit that has an addiction specialist (GPP). Young people Perform a comprehensive HEEADSSS assessment for young people with alcohol problems (Level B). Treatment should focus on tangible benefits of reducing drinking through psychotherapy and engagement of family and peer networks (Level B). Aboriginal and Torres Strait Islander peoples Collaborate with Aboriginal or Torres Strait Islander health workers, organisations and communities, and seek guidance on patient engagement approaches (GPP). Use validated screening tools and consider integrated mainstream and Aboriginal or Torres Strait Islander-specific approaches to care (Level B). Culturally and linguistically diverse groups Use an appropriate method, such as the "teach-back" technique, to assess the need for language and health literacy support (Level C). Engage with culture-specific agencies as this can improve treatment access and success (Level C). Sexually diverse and gender diverse populations Be mindful that sexually diverse and gender diverse populations experience lower levels of satisfaction, connection and treatment completion (Level C). Seek to incorporate LGBTQ-specific treatment and agencies (Level C). Older people All new patients aged over 50 years should be screened for harmful alcohol use (Level D). Consider alcohol as a possible cause for older patients presenting with unexplained physical or psychological symptoms (Level D). Consider shorter acting benzodiazepines for withdrawal management (Level D). Cognitive impairment Cognitive impairment may impair engagement with treatment (Level A). Perform cognitive screening for patients who have alcohol problems and refer them for neuropsychological assessment if significant impairment is suspected (Level A). SUMMARY OF KEY RECOMMENDATIONS AND LEVELS OF EVIDENCE: Chapter 5: Understanding and managing comorbidities for people with alcohol problems: polydrug use and dependence, co-occurring mental disorders, and physical comorbidities Polydrug use and dependence Active alcohol use disorder, including dependence, significantly increases the risk of overdose associated with the administration of opioid drugs. Specialist advice is recommended before treatment of people dependent on both alcohol and opioid drugs (GPP). Older patients requiring management of alcohol withdrawal should have their use of pharmaceutical medications reviewed, given the prevalence of polypharmacy in this age group (GPP). Smoking cessation can be undertaken in patients with alcohol dependence and/or polydrug use problems; some evidence suggests varenicline may help support reduction of both tobacco and alcohol consumption (Level C). Co-occurring mental disorders More intensive interventions are needed for people with comorbid conditions, as this population tends to have more severe problems and carries a worse prognosis than those with single pathology (GPP). The Kessler Psychological Distress Scale (K10 or K6) is recommended for screening for comorbid mental disorders in people presenting for alcohol use disorders (Level A). People with alcohol use disorder and comorbid mental disorders should be offered treatment for both disorders; care should be taken to coordinate intervention (Level C). Physical comorbidities Patients should be advised that alcohol use has no beneficial health effects. There is no clear risk-free threshold for alcohol intake. The safe dose for alcohol intake is dependent on many factors such as underlying liver disease, comorbidities, age and sex (Level A). In patients with alcohol use disorder, early recognition of the risk for liver cirrhosis is critical. Patients with cirrhosis should abstain from alcohol and should be offered referral to a hepatologist for liver disease management and to an addiction physician for management of alcohol use disorder (Level A). Alcohol abstinence reduces the risk of cancer and improves outcomes after a diagnosis of cancer (Level A).

Histotripsy Ablation Alters the Tumor Microenvironment and Promotes Immune System Activation in a Subcutaneous Model of Pancreatic Cancer.

Pancreatic cancer is a significant cause of cancer-related deaths in the United States with an abysmal five-year overall survival rate that is under 9%. Reasons for this mortality include the lack of late-stage treatment options and the immunosuppressive tumor microenvironment. Histotripsy is an ultrasound-guided, noninvasive, nonthermal tumor ablation therapy that mechanically lyses targeted cells. To study the effects of histotripsy on pancreatic cancer, we utilized an in vitro model of pancreatic adenocarcinoma and compared the release of potential antigens following histotripsy treatment to other ablation modalities. Histotripsy was found to release immune-stimulating molecules at magnitudes similar to other nonthermal ablation modalities and superior to thermal ablation modalities, which corresponded to increased innate immune system activation in vivo. In subsequent in vivo studies, murine Pan02 tumors were grown in mice and treated with histotripsy. Flow cytometry and rtPCR were used to determine changes in the tumor microenvironment over time compared to untreated animals. In mice with pancreatic tumors, we observed significantly increased tumor-progression-free and general survival, with increased activation of the innate immune system 24 h posttreatment and decreased tumor-associated immune cell populations within 14 days of treatment. This study demonstrates the feasibility of using histotripsy for pancreatic cancer ablation and provides mechanistic insight into the initial innate immune system activation following treatment. Further work is needed to establish the mechanisms behind the immunomodulation of the tumor microenvironment and immune effects.

Successional dynamics of a 35 year old freshwater mitigation wetland in southeastern New Hampshire.

The long-term ecological success of compensatory freshwater wetland projects has come into question based on follow-up monitoring studies over the past few decades. Given that wetland restoration may require many years to decades to converge to desired outcomes, long-term monitoring of successional patterns may increase our ability to fully evaluate success of wetland mitigation projects or guide adaptive management when needed. In Portsmouth, New Hampshire a 4 ha wetland was constructed in an abandoned gravel quarry as off-site compensatory mitigation for impacts to a scrub-shrub swamp associated with property expansion. Building upon prior evaluations from 1992 and 2002, we conducted a floral survey in 2020 to compare results with prior surveys to document vegetation successional trends over time. In addition, we monitored the avian community throughout the growing season as a measure of habitat quality. The plant community mirrored documented successional trends of freshwater wetland restoration projects as native hydrophytes dominated species composition. Plant species composition stabilized as the rate of turnover, the measurement of succession, declined by nearly half after 17 years. Researchers should consider long-term monitoring of specific sites to better understand successional patterns of created wetlands as we documented long time frames required for the development of scrub-shrub swamps, red maple swamps, and sedge meadows. High species richness was attributed to beaver activity, topographic heterogeneity from Carex stricta tussocks, and the seed bank from the application of peat from the original wetland. Habitat heterogeneity of open water, herbaceous cover, and woody vegetation supports a diverse avian community including 11 wetland dependent species. Although the mitigation project has not created the full area of lost scrub-shrub swamp after 35 years, it has developed a structurally complex habitat and diverse avian community that effectively provides the functions and values of the impacted system.

Establishing an immunocompromised porcine model of human cancer for novel therapy development with pancreatic adenocarcinoma and irreversible electroporation.

New therapies to treat pancreatic cancer are direly needed. However, efficacious interventions lack a strong preclinical model that can recapitulate patients' anatomy and physiology. Likewise, the availability of human primary malignant tissue for ex vivo studies is limited. These are significant limitations in the biomedical device field. We have developed RAG2/IL2RG deficient pigs using CRISPR/Cas9 as a large animal model with the novel application of cancer xenograft studies of human pancreatic adenocarcinoma. In this proof-of-concept study, these pigs were successfully generated using on-demand genetic modifications in embryos, circumventing the need for breeding and husbandry. Human Panc01 cells injected subcutaneously into the ears of RAG2/IL2RG deficient pigs demonstrated 100% engraftment with growth rates similar to those typically observed in mouse models. Histopathology revealed no immune cell infiltration and tumor morphology was highly consistent with the mouse models. The electrical properties and response to irreversible electroporation of the tumor tissue were found to be similar to excised human pancreatic cancer tumors. The ample tumor tissue produced enabled improved accuracy and modeling of the electrical properties of tumor tissue. Together, this suggests that this model will be useful and capable of bridging the gap of translating therapies from the bench to clinical application.

B7-H7 (HHLA2) inhibits T-cell activation and proliferation in the presence of TCR and CD28 signaling.

Modulation of T-cell responses has played a key role in treating cancers and autoimmune diseases. Therefore, understanding how different receptors on T cells impact functional outcomes is crucial. The influence of B7-H7 (HHLA2) and CD28H (TMIGD2) on T-cell activation remains controversial. Here we examined global transcriptomic changes in human T cells induced by B7-H7. Stimulation through TCR with OKT3 and B7-H7 resulted in modest fold changes in the expression of select genes; however, these fold changes were significantly lower than those induced by OKT3 and B7-1 stimulation. The transcriptional changes induced by OKT3 and B7-H7 were insufficient to provide functional stimulation as measured by evaluating T-cell proliferation and cytokine production. Interestingly, B7-H7 was coinhibitory when simultaneously combined with TCR and CD28 stimulation. This inhibitory activity was comparable to that observed with PD-L1. Finally, in physiological assays using T cells and APCs, blockade of B7-H7 enhanced T-cell activation and proliferation, demonstrating that this ligand acts as a break signal. Our work defines that the transcriptomic changes induced by B7-H7 are insufficient to support full costimulation with TCR signaling and, instead, B7-H7 inhibits T-cell activation and proliferation in the presence of TCR and CD28 signaling.

Multi-Tissue Analysis on the Impact of Electroporation on Electrical and Thermal Properties.

OBJECTIVE: Tissue electroporation is achieved by applying a series of electric pulses to destabilize cell membranes within the target tissue. The treatment volume is dictated by the electric field distribution, which depends on the pulse parameters and tissue type and can be readily predicted using numerical methods. These models require the relevant tissue properties to be known beforehand. This study aims to quantify electrical and thermal properties for three different tissue types relevant to current clinical electroporation. METHODS: Pancreatic, brain, and liver tissue were harvested from pigs, then treated with IRE pulses in a parallel-plate configuration. Resulting current and temperature readings were used to calculate the conductivity and its temperature dependence for each tissue type. Finally, a computational model was constructed to examine the impact of differences between tissue types. RESULTS: Baseline conductivity values (mean 0.11, 0.14, and 0.12 S/m) and temperature coefficients of conductivity (mean 2.0, 2.3, and 1.2 % per degree Celsius) were calculated for pancreas, brain, and liver, respectively. The accompanying computational models suggest field distribution and thermal damage volumes are dependent on tissue type. CONCLUSION: The three tissue types show similar electrical and thermal responses to IRE, though brain tissue exhibits the greatest differences. The results also show that tissue type plays a role in the expected ablation and thermal damage volumes. SIGNIFICANCE: The conductivity and its changes due to heating are expected to have a marked impact on the ablation volume. Incorporating these tissue properties aids in the prediction and optimization of electroporation-based therapies.

Starting a Fire Without Flame: The Induction of Cell Death and Inflammation in Electroporation-Based Tumor Ablation Strategies.

New therapeutic strategies and paradigms are direly needed for the treatment of cancer. While the surgical removal of tumors is favored in most cancer treatment plans, resection options are often limited based on tumor localization. Over the last two decades, multiple tumor ablation strategies have emerged as promising stand-alone or combination therapeutic options for patients. These strategies are often employed to treat tumors in areas where surgical resection is not possible or where chemotherapeutics have proven ineffective. The type of cell death induced by the ablation modality is a critical aspect of therapeutic success that can impact the efficacy of the treatment and systemic anti-tumor immune system responses. Electroporation-based ablation technologies include electrochemotherapy, irreversible electroporation, and other modalities that rely on pulsed electric fields to create pores in cell membranes. These pores can either be reversible or irreversible depending on the electric field parameters and can induce cell death either alone or in combination with a therapeutic agent. However, there have been many controversial findings among these technologies as to the cell death type initiated, from apoptosis to pyroptosis. As cell death mechanisms can impact treatment side effects and efficacy, we review the main types of cell death induced by electroporation-based treatments and summarize the impact of these mechanisms on treatment response. We also discuss potential reasons behind the variability of findings such as the similarities between cell death pathways, differences between cell-types, and the variation in electric field strength across the treatment area.

EView: An electric field visualization web platform for electroporation-based therapies.

BACKGROUND AND OBJECTIVES: Electroporation is the phenomenon by which cell membrane permeability to ions and macromolecules is increased when the cell is briefly exposed to high electric fields. In electroporation-based treatments, such exposure is typically performed by delivering high voltage pulses across needle electrodes in tissue. For a given tissue and pulsing protocol, an electric field magnitude threshold exists that must be overreached for treatment efficacy. However, it is hard to preoperatively infer the treatment volume because the electric field distribution intricately depends on the electrodes' positioning and length, the applied voltage, and the electric conductivity of the treated tissues. For illustrating such dependencies, we have created EView (https://eview.upf.edu), a web platform that estimates the electric field distribution for arbitrary needle electrode locations and orientations and overlays it on 3D medical images. METHODS: A client-server approach has been implemented to let the user set the electrode configuration easily on the web browser, whereas the simulation is computed on a dedicated server. By means of the finite element method, the electric field is solved in a 3D volume. For the sake of simplicity, only a homogeneous tissue is modeled, assuming the same properties for healthy and pathologic tissues. The non-linear dependence of tissue conductivity on the electric field due to the electroporation effect is modeled. The implemented model has been validated against a state of the art finite element solver, and the server has undergone a heavy load test to ensure reliability and to report execution times. RESULTS: The electric field is rapidly computed for any electrode and tissue configuration, and alternative setups can be easily compared. The platform provides the same results as the state of the art finite element solver (Dice = 98.3 ± 0.4%). During the high load test, the server remained responsive. Simulations are computed in less than 2 min for simple cases consisting of two electrodes and take up to 40 min for complex scenarios consisting of 6 electrodes. CONCLUSIONS: With this free platform we provide expert and non-expert electroporation users a way to rapidly model the electric field distribution for arbitrary electrode configurations.

Development of a Multi-Pulse Conductivity Model for Liver Tissue Treated With Pulsed Electric Fields.

Pulsed electric field treatment modalities typically utilize multiple pulses to permeabilize biological tissue. This electroporation process induces conductivity changes in the tissue, which are indicative of the extent of electroporation. In this study, we characterized the electroporation-induced conductivity changes using all treatment pulses instead of solely the first pulse as in conventional conductivity models. Rabbit liver tissue was employed to study the tissue conductivity changes caused by multiple, 100 µs pulses delivered through flat plate electrodes. Voltage and current data were recorded during treatment and used to calculate the tissue conductivity during the entire pulsing process. Temperature data were also recorded to quantify the contribution of Joule heating to the conductivity according to the tissue temperature coefficient. By fitting all these data to a modified Heaviside function, where the two turning points (E 0, E 1) and the increase factor (A) are the main parameters, we calculated the conductivity as a function of the electric field (E), where the parameters of the Heaviside function (A and E 0) were functions of pulse number (N). With the resulting multi-factor conductivity model, a numerical electroporation simulation can predict the electrical current for multiple pulses more accurately than existing conductivity models. Moreover, the saturating behavior caused by electroporation can be explained by the saturation trends of the increase factor A in this model. The conductivity change induced by electroporation has a significant increase at about the first 30 pulses, then tends to saturate at 0.465 S/m. The proposed conductivity model can simulate the electroporation process more accurately than the conventional conductivity model. The electric field distribution computed using this model is essential for treatment planning in biomedical applications utilizing multiple pulsed electric fields, and the method proposed here, relating the pulse number to the conductivity through the variables in the Heaviside function, may be adapted to investigate the effect of other parameters, like pulse frequency and pulse width, on electroporation.

Patient Derived Xenografts Expand Human Primary Pancreatic Tumor Tissue Availability for ex vivo Irreversible Electroporation Testing.

New methods of tumor ablation have shown exciting efficacy in pre-clinical models but often demonstrate limited success in the clinic. Due to a lack of quality or quantity in primary malignant tissue specimens, therapeutic development and optimization studies are typically conducted on healthy tissue or cell-line derived rodent tumors that don't allow for high resolution modeling of mechanical, chemical, and biological properties. These surrogates do not accurately recapitulate many critical components of the tumor microenvironment that can impact in situ treatment success. Here, we propose utilizing patient-derived xenograft (PDX) models to propagate clinically relevant tumor specimens for the optimization and development of novel tumor ablation modalities. Specimens from three individual pancreatic ductal adenocarcinoma (PDAC) patients were utilized to generate PDX models. This process generated 15-18 tumors that were allowed to expand to 1.5 cm in diameter over the course of 50-70 days. The PDX tumors were morphologically and pathologically identical to primary tumor tissue. Likewise, the PDX tumors were also found to be physiologically superior to other in vitro and ex vivo models based on immortalized cell lines. We utilized the PDX tumors to refine and optimize irreversible electroporation (IRE) treatment parameters. IRE, a novel, non-thermal tumor ablation modality, is being evaluated in a diverse range of cancer clinical trials including pancreatic cancer. The PDX tumors were compared against either Pan02 mouse derived tumors or resected tissue from human PDAC patients. The PDX tumors demonstrated similar changes in electrical conductivity and Joule heating following IRE treatment. Computational modeling revealed a high similarity in the predicted ablation size of the PDX tumors that closely correlate with the data generated with the primary human pancreatic tumor tissue. Gene expression analysis revealed that IRE treatment resulted in an increase in biological pathway signaling associated with interferon gamma signaling, necrosis and mitochondria dysfunction, suggesting potential co-therapy targets. Together, these findings highlight the utility of the PDX system in tumor ablation modeling for IRE and increasing clinical application efficacy. It is also feasible that the use of PDX models will significantly benefit other ablation modality testing beyond IRE.