Ultra-Low Intensity Post-Pulse Affects Cellular Responses Caused by Nanosecond Pulsed Electric Fields

Area of Science:

• Biophysics
• Cell Biology
• Electroporation

Background:

• High-intensity nanosecond pulse electric fields (nsPEF) are known for inducing regulated cell death and tumor elimination.
• Cellular responses to nsPEF are typically linked to primary pulse characteristics like duration, amplitude, and number.
• The influence of low-intensity post-pulse waveforms has been largely unexplored.

Purpose of the Study:

• To investigate the impact of differing post-pulse waveforms on cellular responses to nsPEF.
• To compare cellular effects generated by two distinct nsPEF pulse generator designs (Blumlein line and pulse forming line) with similar primary pulses but different post-pulses.

Main Methods:

• Utilized Blumlein line (BL) and pulse forming line (PFL) generators producing nsPEF with nearly identical primary pulses (100 ns duration).
• Analyzed differences in post-pulse characteristics (duration, polarity) between BL (~50 µs, opposite polarity) and PFL (~2 µs, same polarity).
• Assessed cellular responses including mitochondrial membrane potential dissipation, cell viability, plasma membrane permeability (PI uptake), reactive oxygen species generation, spare respiratory capacity (SRC), and trans-plasma membrane electron transport (tPMET).

Main Results:

• Different post-pulses led to distinct cellular responses despite similar primary waveforms.
• PFL exhibited lower thresholds for mitochondrial potential dissipation, viability loss, and PI permeability compared to BL.
• PFL decreased SRC, while BL increased it; PFL uniquely induced a biphasic effect on tPMET.

Conclusions:

• Low-intensity post-pulse conditions significantly influence cell responses to nsPEF.
• Post-pulse waveform characteristics must be considered when comparing nsPEF studies, even with similar primary pulse parameters.
• This finding opens new avenues for optimizing nsPEF applications by controlling post-pulse characteristics.