In Vitro Imaging and Molecular Characterization of Ca²⁺ Flux Modulation by Nanosecond Pulsed Electric Fields

In recent years, the application of pulsed electric fields with very short durations (nanoseconds) and extremely high amplitudes (MV/m) has been investigated for novel medical purposes. Various electric protocols have been explored for different objectives, including the utilization of fractionated pulse doses to enhance cell electrosensitization to the uptake of different markers or an increase in apoptosis. This study focused on the use of fluorescence imaging to examine molecular calcium fluxes induced by different fractionated protocols of short electric pulses in neuroblastoma (SH-SY5Y) and mesenchymal stem cells (HaMSCs) that were electroporated using nanosecond pulsed electric fields. In our experimental setup, we did not observe cell electrosensitization in terms of an increase in calcium flux following the administration of fractionated doses of nanosecond pulsed electric fields with respect to the non-fractionated dose. However, we observed the targeted activation of calcium-dependent genes (c-FOS, c-JUN, EGR1, NURR-1, β3-TUBULIN) based on the duration of calcium flux, independent of the instantaneous levels achieved but solely dependent on the final plateau reached. This level of control may have potential applications in various medical and biological treatments that rely on calcium and the delivery of nanosecond pulsed electric fields.