Nanosecond pulses targeting intracellular ablation increase destruction of tumor cells with irregular morphology

Enhanced Cellular Doxorubicin Uptake via Delayed Exposure Following Nanosecond Pulsed Electric Field Treatment: An In Vitro Study

The combination of nanosecond Pulsed Electric Field (nsPEF) with pharmaceuticals is a pioneering therapeutic method capable of enhancing drug uptake efficacy in cells. Utilizing nsPEFs configured at 400 pulses, an electric field strength of 15 kV/cm, a pulse duration of 100 ns, and a repetition rate of 10 pulses per second (PPS), we combined the nsPEF with a low dose of doxorubicin (DOX) at 0.5 μM. Upon verifying that cells could continuously internalize DOX from the surrounding medium within 1 h post nsPEF exposure, we set the DOX exposure period to 10 min and contrasted the outcomes of varying sequences of DOX and nsPEF administration: pulsing followed by DOX, DOX followed by pulsing, and DOX applied 40 min after pulsing. Flow cytometry, CCK-8 assays, and transmission electron microscopy (TEM) were employed to examine intracellular DOX accumulation, cell viability, apoptosis, cell cycle, and ultrastructural transformations. Our findings demonstrate that exposing cells to DOX 40 min subsequent to nsPEF treatment can effectively elevate intracellular DOX levels, decrease cell viability, and inhibit the cell cycle. This research work presents a novel approach to enhance DOX uptake efficiency with moderate conditions of both DOX and nsPEF.

Optimal Irreversible Electroporation Combined with Nano-Enabled Immunomodulatory to Boost Systemic Antitumor Immunity

In this work, we proposed nµPEF, a novel pulse configuration combining nanosecond and microsecond pulses (nµPEF), to enhance tumor ablation in irreversible electroporation (IRE) for oncological therapy. nµPEF demonstrated improved efficacy in inducing immunogenic cell death, positioning it as a potential candidate for next-generation ablative therapy. However, the immune response elicited by nµPEF alone was insufficient to effectively suppress distant tumors. To address this limitation, we developed PPR@CM-PD1, a genetically engineered nanovesicle. PPR@CM-PD1 employed a polyethylene glycol-polylactic acid-glycolic acid (PEG-PLGA) nanoparticle encapsulating the immune adjuvant imiquimod and coated with a genetically engineered cell membrane expressing programmed cell death protein 1 (PD1). This design allowed PPR@CM-PD1 to target both the innate immune system through toll-like receptor 7 (TLR7) agonism and the adaptive immune system through programmed cell death protein 1/programmed cell death-ligand 1 (PD1/PDL1) checkpoint blockade. In turn, nµPEF facilitated intratumoral infiltration of PPR@CM-PD1 by modulating the tumor stroma. The combination of nµPEF and PPR@CM-PD1 generated a potent and systemic antitumor immune response, resulting in remarkable suppression of both nµPEF-treated and untreated distant tumors (abscopal effects). This interdisciplinary approach presents a promising perspective for oncotherapy and holds great potential for future clinical applications.

Engineering high post-electroporation viabilities and transfection efficiencies for elongated cells on suspended nanofiber networks

The impact of cell shape on cell membrane permeabilization by pulsed electric fields is not fully understood. For certain applications, cell survival and recovery post-treatment is either desirable, as in gene transfection, electrofusion, and electrochemotherapy, or is undesirable, as in tumor and cardiac ablations. Understanding of how morphology affects cell viability post-electroporation may lead to improved electroporation methods. In this study, we use precisely aligned nanofiber networks within a microfluidic device to reproducibly generate elongated cells with controlled orientations to an applied electric field. We show that cell viability is significantly dependent on cell orientation, elongation, and spread. Further, these trends are dependent on the external buffer conductivity. Additionally, we see that cell survival for elongated cells is still supported by the standard pore model of electroporation. Lastly, we see that manipulating the cell orientation and shape can be leveraged for increased transfection efficiencies when compared to spherical cells. An improved understanding of cell shape and pulsation buffer conductivity may lead to improved methods for enhancing cell viability post-electroporation by engineering the cell morphology, cytoskeleton, and electroporation buffer conditions.

In Vitro Experimental and Numerical Studies on the Preferential Ablation of Chemo-Resistant Tumor Cells Induced by High-Voltage Nanosecond Pulsed Electric Fields

Chemoresistance causes tumor recurrence and metastasis, resulting in poor clinical outcomes and low survival, and has been considered an obstacle to tumor therapy. The development of novel therapeutic approaches that can effectively kill chemoresistant tumor cells (CRTCs) is therefore critical to overcoming these obstacles.

OBJECTIVE

Here, we introduce an emerging physical feature-based therapeutic approach based on nanosecond pulsed electric fields (nsPEFs). The goal of this study is to investigate the effect of nsPEFs on CRTCs.

METHODS

The cell viability, ablation effects on a 3D-cultured scaffold, and lethal thresholds of nsPEFs were evaluated according to fluorescence staining assays.

RESULTS

nsPEF treatment preferentially affected chemoresistant cells (A549/CDDP) with a higher cell viability inhibition ability/cell death rate, larger ablation area, and lower ablation threshold compared to their respective homologous tumor cells (A549). The experimental and theoretical studies suggested that nsPEFs displayed selective behavior toward intracellular structures. With this selective character, nsPEFs can induce higher electroporation effects (e.g., higher pore number, larger electroporation area, and faster fluorescence dissipation on the nuclear envelope) on CRTCs due to their larger nuclear size and cell membrane capacitance.

CONCLUSION

These findings demonstrated that nsPEFs induced preferential ablation of CRTCs over their respective homologous tumor cells.

SIGNIFICANCE

This study provides an experimental and theoretical basis for the study of killing CRTCs by electrical treatments and suggests potential applications in the optimization of novel anti-chemoresistance methods.