Abstract:Irreversible electroporation (IRE) is an emerging focal therapy which is demonstrating utility in the treatment of unresectable tumors where thermal ablation techniques are contraindicated. IRE uses ultra-short duration, high-intensity monopolar pulsed electric fields to permanently disrupt cell membranes within a well-defined volume. Though preliminary clinical results for IRE are promising, implementing IRE can be challenging due to the heterogeneous nature of tumor tissue and the unintended induction of mus… Show more
“…applications that utilize controlled, square electrical pulses on the order of one microsecond [19,58]. The observations about PEFs with single-microsecond pulse widths from the field of PEF-based food processing do not directly provide information on the efficiency of these pulses to enhance molecular transport across mammalian cell membranes.…”
Section: Accepted Manuscriptmentioning
confidence: 98%
“…estimates When PI binds to nucleic acids, it undergoes a dramatic fluorescence increase, making it useful in assays for evaluating membrane integrity, such as cell death [19] or membrane permeabilization [67,66], which rely on a binary result. Continuous measurements have been performed [65] using chemical agents to calibrate fluorescence intensity measurements, though they have not been used to study the temporal evolution of membrane permeability induced by electric fields with pulse widths on the order of the characteristic membrane charging time.…”
Section: Objective Analysis Of Different Electroporation Protocols Mamentioning
confidence: 99%
“…In irreversible electroporation (IRE), the cellular membrane is disrupted to generate an irrecoverable homeostatic imbalance [18,19,20,21]. In gene electrotransfer (GET) [22,23] or electrochemotherapy (ECT) [24,25,26], electroporation enables therapeutic molecules to be more efficiently delivered into cells.…”
High-frequency bipolar electric pulses have been shown to mitigate undesirable muscle contraction during irreversible electroporation (IRE) therapy. Here, we evaluate the potential applicability of such pulses for introducing exogenous molecules into cells, such as in electrochemotherapy (ECT). For this purpose we develop a method for calculating the time course of the effective permeability of an electroporated cell membrane based on real-time imaging of propidium transport into single cells that allows a quantitative comparison between different pulsing schemes. We calculate the effective permeability for several pulsed electric field treatments including trains of 100μs monopolar pulses, conventionally used in IRE and ECT, and pulse trains containing bursts or evenly-spaced 1μs bipolar pulses. We show that shorter bipolar pulses induce lower effective membrane permeability than longer monopolar pulses with equivalent treatment times. This lower efficiency can be attributed to incomplete membrane charging. Nevertheless, bipolar pulses could be used for increasing the uptake of small molecules into cells more symmetrically, but at the expense of higher applied voltages. These data indicate that high-frequency bipolar bursts of electrical pulses may be designed to electroporate cells as effectively as and more homogeneously than conventional monopolar pulses.
“…applications that utilize controlled, square electrical pulses on the order of one microsecond [19,58]. The observations about PEFs with single-microsecond pulse widths from the field of PEF-based food processing do not directly provide information on the efficiency of these pulses to enhance molecular transport across mammalian cell membranes.…”
Section: Accepted Manuscriptmentioning
confidence: 98%
“…estimates When PI binds to nucleic acids, it undergoes a dramatic fluorescence increase, making it useful in assays for evaluating membrane integrity, such as cell death [19] or membrane permeabilization [67,66], which rely on a binary result. Continuous measurements have been performed [65] using chemical agents to calibrate fluorescence intensity measurements, though they have not been used to study the temporal evolution of membrane permeability induced by electric fields with pulse widths on the order of the characteristic membrane charging time.…”
Section: Objective Analysis Of Different Electroporation Protocols Mamentioning
confidence: 99%
“…In irreversible electroporation (IRE), the cellular membrane is disrupted to generate an irrecoverable homeostatic imbalance [18,19,20,21]. In gene electrotransfer (GET) [22,23] or electrochemotherapy (ECT) [24,25,26], electroporation enables therapeutic molecules to be more efficiently delivered into cells.…”
High-frequency bipolar electric pulses have been shown to mitigate undesirable muscle contraction during irreversible electroporation (IRE) therapy. Here, we evaluate the potential applicability of such pulses for introducing exogenous molecules into cells, such as in electrochemotherapy (ECT). For this purpose we develop a method for calculating the time course of the effective permeability of an electroporated cell membrane based on real-time imaging of propidium transport into single cells that allows a quantitative comparison between different pulsing schemes. We calculate the effective permeability for several pulsed electric field treatments including trains of 100μs monopolar pulses, conventionally used in IRE and ECT, and pulse trains containing bursts or evenly-spaced 1μs bipolar pulses. We show that shorter bipolar pulses induce lower effective membrane permeability than longer monopolar pulses with equivalent treatment times. This lower efficiency can be attributed to incomplete membrane charging. Nevertheless, bipolar pulses could be used for increasing the uptake of small molecules into cells more symmetrically, but at the expense of higher applied voltages. These data indicate that high-frequency bipolar bursts of electrical pulses may be designed to electroporate cells as effectively as and more homogeneously than conventional monopolar pulses.
“…S10 and S11). It has been previously observed that H-FIRE treatment generates more homogenous lesions (2,24,(27)(28)(29)(30)(31) and in this article, we offer an explanation for that phenomenon.…”
Many approaches for studying the transmembrane potential (TMP) induced during the treatment of biological cells with pulsed electric fields have been reported. From the simple analytical models to more complex numerical models requiring significant computational resources, a gamut of methods have been used to recapitulate multicellular environments in silico. Cells have been modeled as simple shapes in two dimensions as well as more complex geometries attempting to replicate realistic cell shapes. In this study, we describe a method for extracting realistic cell morphologies from fluorescence microscopy images to generate the piecewise continuous mesh used to develop a finite element model in two dimensions. The preelectroporation TMP induced in tightly packed cells is analyzed for two sets of pulse parameters inspired by clinical irreversible electroporation treatments. We show that high-frequency bipolar pulse trains are better, and more homogeneously raise the TMP of tightly packed cells to a simulated electroporation threshold than conventional irreversible electroporation pulse trains, at the expense of larger applied potentials. Our results demonstrate the viability of our method and emphasize the importance of considering multicellular effects in the numerical models used for studying the response of biological tissues exposed to electric fields.
“…The cell-killing effects of H-FIRE were later explored using 3D in vitro tumor constructs and in vivo subcutaneous murine tumors over a wide range of pulse durations (250 ns-100 µs) (41). The in vitro tumor constructs were assembled by mixing murine pancreatic tumor cells with collagen I hydrogel, injecting into cylindrical molds, and polymerizing at 37°C (42); the in vivo subcutaneous tumors were produced by injecting human GBM cells (DBTRG-05MG) into the dorsolateral flank region of athymic nude-Foxn1 nu mice.…”
Glioblastoma (GBM) is the most common and aggressive primary brain tumor in adults. Approximately 9180 primary GBM tumors are diagnosed in the United States each year, in which median survival is up to 16 months. GBM eludes and resists typical cancer treatments due to the presence of infiltrative cells beyond the solid tumor margin, heterogeneity within the tumor microenvironment, and protection from the blood-brain barrier. Conventional treatments for GBM, such as surgical resection, radiotherapy, and chemotherapy, have shown limited efficacy;IRE and H-FIRE for the Eradication of GBM 374 therefore, alternate treatments are needed. Tumor chemoresistance and its proximity to critical structures make GBM a prime theoretical candidate for nonthermal ablation with irreversible electroporation (IRE) and high-frequency IRE (H-FIRE). IRE and H-FIRE are treatment modalities that utilize pulsed electric fields to permeabilize the cell membrane. Once the electric field magnitude exceeds a tissue-specific lethal threshold, cell death occurs. Benefits of IRE and H-FIRE therapy include, but are not limited to, the elimination of cytotoxic effects, sharp delineation from treated tissue and spared tissue, a nonthermal mechanism of ablation, and sparing of nerves and major blood vessels. Preclinical studies have confirmed the safety and efficacy of IRE and H-FIRE within their experimental scope. In this chapter, studies will be collected and information extrapolated to provide possible treatment regimens for use in high-grade gliomas, specifically in GBM.
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