The biological response of cells to nanosecond pulsed electric fields is dependent on plasma membrane cholesterol

Abstract

Previous work from our laboratory demonstrated nanopore formation in cell membranes following exposure to nanosecond pulsed electric fields (nsPEF). We observed differences in sensitivity to nsPEF in both acute membrane injury and 24h lethality across multiple cells lines. Based on these data, we hypothesize that the biological response of cells to nsPEF is dependent on the physical properties of the plasma membrane (PM), including regional cholesterol content. Results presented in this paper show that depletion of membrane cholesterol disrupts the PM and increases the permeability of cells to small molecules, including propidium iodide and calcium occurring after fewer nsPEF. Additionally, cholesterol depletion concurrently decreases the "dose" of nsPEF required to induce lethality. In summary, the results of the current study suggest that the PM cholesterol composition is an important determinant in the cellular response to nsPEF.

A thermodynamic scaling law for electrically perturbed lipid membranes: validation with the steepest-entropy-ascent framework

“…Lower cholesterol content corresponded to higher susceptibility to a μsPEF as measured by the viability of the cell population after exposure ( Figure 1A). Furthermore, as has been shown previously for nsPEF [28], we see an increased susceptibility of the MDA-MB-231 cells to a PEF when the cholesterol content of the membrane is pharmacologically reduced with acute exposure to methyl-β-cyclodextrin (MβCD; see Figure 1B). These observations are analogous to the ones made by Kraske and Mountcastle, albeit with the caution of not over generalizing the importance of cholesterol in PEF susceptibility.…”

“…In this study, we show that cholesterol content in mammalian cells dictate their susceptibility to μsPEFs (Figure 1). As pointed out, such observations have also been made for nsPEFs [28]. In mammalian cells, cholesterol-rich ordered domains exist as shown in Figure 1C.…”

Nanosecond pulsed electric field exposure does not induce the unfolded protein response in adult human dermal fibroblasts

“…We hypothesized that as a result of nsPEFs, permeabilization of the ER membrane would allow for the indiscriminate passage of molecules into and out of the sensitive ER luminal environment [Schoenbach et al, ], changes in intracellular calcium concentration [Beier et al, ; Semenov et al, ], oxidative stress [Pakhomova et al, ], and potential ATP shortage. Other noted observations related to nsPEF exposure, such as dependence on membrane concentrations of cholesterol [Cantu et al, ], PIP2 activation and dynamics [Tolstykh et al, ], cytoskeletal disruption effects and plasma membrane reorganization [Thompson et al, ], and nuclear envelope structure changes [Thompson et al, ], have all been shown to alter UPR dynamics and cell metabolism [Bravo et al, ]. Consequently, this change in molecular environment would not allow for proper protein folding, generating ER stress and activation of the UPR.…”

600-ns pulsed electric fields affect inactivation and antibiotic susceptibilities of Escherichia coli and Lactobacillus acidophilus

“…A Marx bank capacitor system ( Fig. 1a), previously described (Ibey et al 2014;Cantu et al 2016), was used to generate the 600-ns unipolar pulse ( Fig. 1b).…”