Human Amniotic Material Use in Post-Infarct Surgery to Mitigate Pathological Cardiac Outcomes

Many different factors contribute to the development and progression of heart disease. Although substantial advancements have recently been established in the treatment and prevention of heart disease, it continues to produce one in every four deaths in the United States3. This indicates a growing need for treatment options for both cardiovascular disease and its related complications. Human Amniotic Material (HAM) presents a treatment option for the preservation of myocardial functionality as well as prevention of post-operative pericardial inflammation and development of altered electrical activity in the heart. Our research has shown that the application of HAM led to a significant reduction in the development of post-operative atrial fibrillation in humans undergoing cardiac surgery. Furthermore, HAM injection in an ischemic mouse model led to reduced pathological remodeling of the left ventricle, demonstrating its ability to improve the retention of cardiac function in ischemic tissues

Electroporation and Cell Killing by Milli- to Nanosecond Pulses and Avoiding Neuromuscular Stimulation in Cancer Ablation

Ablation therapies aim at eradication of tumors with minimal impact on surrounding healthy tissues. Conventional pulsed electric field (PEF) treatments cause pain and muscle contractions far beyond the ablation area. The ongoing quest is to identify PEF parameters efficient at ablation but not at stimulation. We measured electroporation and cell killing thresholds for 150 ns–1 ms PEF, uni- and bipolar, delivered in 10- to 300-pulse trains at up to 1 MHz rates. Monolayers of murine colon carcinoma cells exposed to PEF were stained with YO-PRO-1 dye to detect electroporation. In 2–4 h, dead cells were labeled with propidium. Electroporation and cell death thresholds determined by matching the stained areas to the electric field intensity were compared to nerve excitation thresholds (Kim et al. in Int J Mol Sci 22(13):7051, 2021). The minimum fourfold ratio of cell killing and stimulation thresholds was achieved with bipolar nanosecond PEF (nsPEF), a sheer benefit over a 500-fold ratio for conventional 100-µs PEF. Increasing the bipolar nsPEF frequency up to 100 kHz within 10-pulse bursts increased ablation thresholds by \u3c 20%. Restricting such bursts to the refractory period after nerve excitation will minimize the number of neuromuscular reactions while maintaining the ablation efficiency and avoiding heating

How to Alleviate Cardiac Injury From Electric Shocks at the Cellular Level

Electric shocks, the only effective therapy for ventricular fibrillation, also electroporate cardiac cells and contribute to the high-mortality post-cardiac arrest syndrome. Copolymers such as Poloxamer 188 (P188) are known to preserve the membrane integrity and viability of electroporated cells, but their utility against cardiac injury from cardiopulmonary resuscitation (CPR) remains to be established. We studied the time course of cell killing, mechanisms of cell death, and protection with P188 in AC16 human cardiomyocytes exposed to micro- or nanosecond pulsed electric field (μsPEF and nsPEF) shocks. A 3D printer was customized with an electrode holder to precisely position electrodes orthogonal to a cell monolayer in a nanofiber multiwell plate. Trains of nsPEF shocks (200, 300-ns pulses at 1.74 kV) or μsPEF shocks (20, 100-μs pulses at 300 V) produced a non-uniform electric field enabling efficient measurements of the lethal effect in a wide range of the electric field strength. Cell viability and caspase 3/7 expression were measured by fluorescent microscopy 2–24 h after the treatment. nsPEF shocks caused little or no caspase 3/7 activation; most of the lethally injured cells were permeable to propidium dye already at 2 h after the exposure. In contrast, μsPEF shocks caused strong activation of caspase 3/7 at 2 h and the number of dead cells grew up to 24 h, indicating the prevalence of the apoptotic death pathway. P188 at 0.2–1% reduced cell death, suggesting its potential utility in vivo to alleviate electric injury from defibrillation

Pulsed Electric Field Ablation of Esophageal Malignancies and Mitigating Damage to Smooth Muscle: An In Vitro Study

Cancer ablation therapies aim to be efficient while minimizing damage to healthy tissues. Nanosecond pulsed electric field (nsPEF) is a promising ablation modality because of its selectivity against certain cell types and reduced neuromuscular effects. We compared cell killing efficiency by PEF (100 pulses, 200 ns–10 µs duration, 10 Hz) in a panel of human esophageal cells (normal and pre-malignant epithelial and smooth muscle). Normal epithelial cells were less sensitive than the pre-malignant ones to unipolar PEF (15–20% higher LD50, p \u3c 0.05). Smooth muscle cells (SMC) oriented randomly in the electric field were more sensitive, with 30–40% lower LD50 (p \u3c 0.01). Trains of ten, 300-ns pulses at 10 kV/cm caused twofold weaker electroporative uptake of YO-PRO-1 dye in normal epithelial cells than in either pre-malignant cells or in SMC oriented perpendicularly to the field. Aligning SMC with the field reduced the dye uptake fourfold, along with a twofold reduction in Ca2+ transients. A 300-ns pulse induced a twofold smaller transmembrane potential in cells aligned with the field, making them less vulnerable to electroporation. We infer that damage to SMC from nsPEF ablation of esophageal malignancies can be minimized by applying the electric field parallel to the predominant SMC orientation

Research Photo: Electric Field Thresholds for Electroporation and Cell Death by Milli- to Nanosecond Pulses: How to Avoid Neuromuscular Stimulation in Cancer Ablation

Research photo: “Electric field thresholds for electroporation and cell death by milli- to nanosecond pulses: How to avoid neuromuscular stimulation in cancer ablation”https://digitalcommons.odu.edu/bioelectrics-2021retreat-images/1008/thumbnail.jp

Electric Field Thresholds for Electroporation and Cell Death by Milli- To Nanosecond Pulses: How to Avoid Neuromuscular Stimulation in Cancer Ablation

Pulsed electric field (PEF) ablation treatments utilize irreversible electroporation and are advantageous in their ability to target cellular components while leaving the vasculature and structural components intact. However, PEF therapies come with the known caveat of neuromuscular excitation outside of the ablation area, causing pain and involuntary muscle contraction. We performed a thorough examination of PEF ablation parameters, including pulse duration, pulse number, and frequency for both uni- and bipolar waveforms with the goal of minimizing neuromuscular excitation. This was done by measuring electroporation and ablation thresholds for 150 ns - 1 ms PEF, uni- and bipolar, delivered in 10-300 pulse trains at up to 1 MHz rates. The ratio between the measured ablation thresholds and already established nerve stimulation thresholds determines the span of neuromuscular effects beyond the ablated region. We found that this ratio is reduced more than 100-fold with the use of bipolar nanosecond-range PEF, in comparison to conventional methods using 100 µs unipolar pulses. This translates to a 10-fold reduction in the tissue radius excited by PEF treatments (see image). Additionally, packing nanosecond PEF into high-frequency bursts promises to reduce the number of neuromuscular responses with minimal impact on ablation efficacy. PEF ablation with bipolar nanosecond pulses is expected to produce far fewer neuromuscular side effects than conventional protocols for irreversible electroporation

Nanosecond Pulse Bursts for Neuron Stimulation

Nanosecond pulsed electrical field (nsPEF) is a novel approach for neuron stimulation however, applicability is limited due to the required relatively high electric field that could result in neuron damage. We reached the stimulation threshold using lower pulse amplitudes by applying a burst of multiple pulses (up to 4 MHz). Action potential (AP) in rat neurons in vitro was registered using a fluorescent probe, FluoVolt. We determined neuron excitation thresholds modulating burst parameters: number of pulses (1-1000), repetition rates (1 Hz-4 MHz) and duration (100 ns, 400 ns, 800 ns). Time-average electrical field values were used to compare nsPEF bursts and single pulse protocols. nsPEF burst exhibits lower time-average electrical field thresholds compared to single-pulse stimulations. Bursts of 100 ns pulses at 100 kHz for 100 µs caused neuron stimulation at 32.8 V/cm time-average electric field, where a single 100 µs pulse requires 165.7 V/cm, resulting in 80% reduction. Multiple stimulation and evaluation of corresponding AP trace shapes were used to identify neuron damage. µs pulses and nsPEF bursts at 250 kHz and above resulted in 100 stimulations without neuron damage. nsPEF bursts of lower pulse repetition rates required higher electrical field peak strengths, resulting in neuron damage visible as distorted AP trace or lack of excitation. Neuron stimulation can be achieved using nsPEF bursts that allow reducing electric field threshold without causing cellular damage

Peculiarities of neurostimulation by intense nanosecond pulsed electric fields: how to avoid firing in peripheral nerve fibers

Intense pulsed electric fields (PEF) are a novel modality for the efficient and targeted ablation of tumors by electroporation. The major adverse side effects of PEF therapies are strong involuntary muscle contractions and pain. Nanosecond-range PEF (nsPEF) are less efficient at neurostimulation and can be employed to minimize such side effects. We quantified the impact of the electrode configuration, PEF strength (up to 20 kV/cm), repetition rate (up to 3 MHz), bi- and triphasic pulse shapes, and pulse duration (down to 10 ns) on eliciting compound action potentials (CAPs) in nerve fibers. The excitation thresholds for single unipolar but not bipolar stimuli followed the classic strength-duration dependence. The addition of the opposite polarity phase for nsPEF increased the excitation threshold, with symmetrical bipolar nsPEF being the least efficient. Stimulation by nsPEF bursts decreased the excitation threshold as a power function above a critical duty cycle of 0.1%. The threshold reduction was much weaker for symmetrical bipolar nsPEF. Supramaximal stimulation by high-rate nsPEF bursts elicited only a single CAP as long as the burst duration did not exceed the nerve refractory period. Such brief bursts of bipolar nsPEF could be the best choice to minimize neuromuscular stimulation in ablation therapies.info:eu-repo/semantics/publishedVersio

Pulsed Electric Field Ablation of Esophageal Malignancies and Mitigating Damage to Smooth Muscle: An In Vitro Study

Cancer ablation therapies aim to be efficient while minimizing damage to healthy tissues. Nanosecond pulsed electric field (nsPEF) is a promising ablation modality because of its selectivity against certain cell types and reduced neuromuscular effects. We compared cell killing efficiency by PEF (100 pulses, 200 ns–10 µs duration, 10 Hz) in a panel of human esophageal cells (normal and pre-malignant epithelial and smooth muscle). Normal epithelial cells were less sensitive than the pre-malignant ones to unipolar PEF (15–20% higher LD50, p < 0.05). Smooth muscle cells (SMC) oriented randomly in the electric field were more sensitive, with 30–40% lower LD50 (p < 0.01). Trains of ten, 300-ns pulses at 10 kV/cm caused twofold weaker electroporative uptake of YO-PRO-1 dye in normal epithelial cells than in either pre-malignant cells or in SMC oriented perpendicularly to the field. Aligning SMC with the field reduced the dye uptake fourfold, along with a twofold reduction in Ca2+ transients. A 300-ns pulse induced a twofold smaller transmembrane potential in cells aligned with the field, making them less vulnerable to electroporation. We infer that damage to SMC from nsPEF ablation of esophageal malignancies can be minimized by applying the electric field parallel to the predominant SMC orientation