The principal bioeffect of the nanosecond pulsed electric field (nsPEF) is a lasting cell membrane permeabilization, which is often attributed to the formation of nanometer-sized pores. Such pores may be too small for detection by the uptake of fluorescent dyes. We tested if Ca²⁺, Cd²⁺, Zn²⁺, and Ba²⁺ ions can be used as nanoporation markers. Time-lapse imaging was performed in CHO, BPAE, and HEK cells loaded with Fluo-4, Calbryte, or Fluo-8 dyes. Ca²⁺ and Ba²⁺ did not change fluorescence in intact cells, whereas their entry after nsPEF increased fluorescence within 7 kV/cm for the formation of larger pores that admitted YO-PRO-1, TO-PRO-3, or propidium dye into the cells. Ba²⁺ entry caused a gradual emission rise, which reached a stable level in 2 min or, with more intense nsPEF, kept rising steadily for at least 30 min. Ca²⁺ entry could elicit calcium-induced calcium release (CICR) followed by Ca²⁺ removal from the cytosol, which markedly affected the time course, polarity, amplitude, and the dose-dependence of fluorescence change. Both Ca²⁺ and Ba²⁺ proved as sensitive nanoporation markers, with Ba²⁺ being more reliable for monitoring membrane damage and resealing.

Gelonin is a ribosome-inactivating protein with extreme intracellular toxicity but poor permeation into cells. Targeted disruption of cell membranes to facilitate gelonin entry is explored for cancer and tissue ablation. We demonstrate a hundreds- to thousands-fold enhancement of gelonin cytotoxicity by pulsed electric fields in the T24, U-87, and CT26 cell lines. The effective gelonin concentration to kill 50% of cells (EC₅₀) after electroporation ranged from <1 nM to about 100 nM. For intact cells, the EC₅₀ was unattainable even at the highest gelonin concentration of 1000 nM, which reduced cell survival by only 5–15%. For isoeffective electroporation treatments using 300 ns, 9 µs, and 100 µs pulses, longer pulses were more efficient at lowering gelonin EC₅₀. Increasing the electric field strength of 8, 100 µs pulses from 0.65 to 1.25 kV/cm reduced gelonin EC₅₀ from 128 nM to 0.72 nM. Conversely, the presence of 100 nM gelonin enabled a more than 20-fold reduction in the number of pulses required for equivalent cell killing. Pulsed electric field-mediated delivery of gelonin shows promise for hyperplasia ablation at concentrations sufficiently low to minimize or avoid systemic toxicity.

Background/Objectives: Esophageal squamous cell carcinoma (ESCC) is an aggressive malignancy with poor prognosis and limited treatment options, highlighting the need for reliable preclinical models for translational research. Although xenograft models are widely used in cancer biology, systematic characterization of subcutaneous ESCC models under defined implantation conditions remains limited. The objective of this study was to systematically compare implantation conditions and define histopathological and growth-related parameters that enable reproducible tumor establishment while maintaining a practical experimental window for therapeutic studies. Methods: We established and characterized a subcutaneous ESCC xenograft model using human ESCC cell line KYSE-30 implanted into immunodeficient J:NU mice. Tumor growth dynamics were compared under three implantation conditions: cells suspended in phosphate-buffered saline (PBS), Matrigel (Corning, basement membrane matrix), or Matrigel diluted with PBS. Results: Tumors generated from Matrigel-embedded cells exhibited rapid growth, reaching substantial size within approximately one week after implantation, which limited their utility for controlled therapeutic studies. In contrast, tumors generated from cells suspended in Matrigel + PBS demonstrated slower but consistent expansion, providing a more suitable and reproducible experimental window for therapeutic intervention. Cells injected in PBS alone showed inefficient tumor establishment. Histopathologic and immunohistochemical analyses revealed matrix-dependent differences in necrosis, stromal organization, and proliferative activity, while confirming epithelial tumor identity and baseline vascularization. Conclusions: Collectively, these findings define a reproducible KYSE-30 subcutaneous xenograft model and identify Matrigel dilution with PBS as an optimal implantation strategy that balances reliable tumor engraftment with controlled tumor growth suitable for therapeutic studies.