Insights into selective action of microsecond pulsed electric fields on healthy and cancer stem cells (D283)

In the last few years, pulsed electric fields have emerged as promising clinical tools for tumor treatments. This study highlights the distinct impact of a specific pulsed electric field protocol named PEF-5 (0.3 MV/m, 40 µs, 5 pulses) on astrocytes (NHA), medulloblastoma (D283) and gli-oblastoma (U87 NS) cancer stem-like cells. We pursued this goal performing ultrastructural analyses corroborated by molecular/omics approaches to understand the vulnerability or re-sistance mechanisms triggered by PEF-5 exposure in the different cell types. Electron microscopic analyses showed that, independently of exposed cells, the main targets of PEF-5 were the cell membrane and the cytoskeleton, presenting indiscriminate filopodia disappearance on the cell surface accompanied by a rapid cell swelling. Nevertheless, cells activated different responses stemming from intracellular organelles. NHA triggered a protective mechanism to recover from the damaged membranes and eliminated the detrimental ROS to maintain cell vital functions. Conversely, PEF-5 induced a different action on mitochondria of cancer stem-like cells, more prominent on D283 compared to U87 NS cells, in correlation with a higher basal level of CD133 protein in D283 cells. In this case, a complete mitochondrial dysfunction was demonstrated, inhibiting the recovery of D283 vital processes, while a mild perturbation was observed in mito-chondria of U87 NS cells, not sufficient to impair their cell functions. Altogether, these results suggest the possibility to use PEF-based technology as a novel strategy to target selectively mi-tochondria of CSCs, preserving healthy cells. Ultrastructural analysis, supported by transcriptomic characterization in microsecond pulsed electric field exposed normal brain and brain tumor cells. Gene expression was measured using Affymetrix platform in control and PEF-5 exposed D283_Med cells 24h after exposure.