Extracellular-Ca2+-Induced Decrease in Small Molecule Electrotransfer Efficiency: Comparison between Microsecond and Nanosecond Electric Pulses

Abstract

Electroporation—a transient electric-field-induced increase in cell membrane permeability—can be used to facilitate the delivery of anticancer drugs for antitumour electrochemotherapy. In recent years, Ca2+ electroporation has emerged as an alternative modality to electrochemotherapy. The antitumor effect of calcium electroporation is achieved as a result of the introduction of supraphysiological calcium doses. However, calcium is also known to play a key role in membrane resealing, potentially altering the pore dynamics and molecular delivery during electroporation. To elucidate the role of calcium for the electrotransfer of small charged molecule into cell we have performed experiments using nano- and micro-second electric pulses. The results demonstrate that extracellular calcium ions inhibit the electrotransfer of small charged molecules. Experiments revealed that this effect is related to an increased rate of membrane resealing. We also employed mathematical modelling methods in order to explain the differences between the CaCl2 effects after the application of nano- and micro-second duration electric pulses. Simulation showed that these differences occur due to the changes in transmembrane voltage generation in response to the increase in specific conductivity when CaCl2 concentration is increased.

In Vitro Study of Calcium Microsecond Electroporation of Prostate Adenocarcinoma Cells

“…MD simulations have already proved that the presence of Ca 2+ has almost no effect on the pore lifetime [ 65 ]. Calcium changes though the conductivity of the electroporation buffer and consequently might have an impact on transmembrane voltage generation [ 66 ]. This effect is more pronounced once nanosecond PEFs are applied.…”

Simulation study of cell transmembrane potential and electroporation induced by time-varying magnetic fields

“…According to the Faraday law of electromagnetic induction, a TMF with a higher frequency can generate an intenser electric field, leading to the occurrence of EP effect. Similar to the EP studies with pulsed electric fields, in the condition of the equal energy import, the EP can be intensified with a pulse with a higher frequency, supported by the experimental studies [43] (indicated by the shift of fluorescence dyes) and the simulation studies [44] (indicated by the pore density and…”

Simulation study of Cell Transmembrane Potential and Electroporation Induced by Time-Varying Magnetic Fields

“…According to the Faraday law of electromagnetic induction, a TMF with a higher frequency can generate an intenser electric field, leading to the occurrence of EP effect. Similar to the EP studies with pulsed electric fields, in the condition of the equal energy import, the EP can be intensified with a pulse with a higher frequency, supported by the experimental studies [43] (indicated by the shift of fluorescence dyes) and the simulation studies [44] (indicated by the pore density and radius).…”