Electromediated formation of DNA complexes with cell membranes and its consequences for gene delivery

TL;DR

This study investigates the rapid formation and localization of DNA complexes on cell membranes during electroporation, providing insights into the mechanisms behind electro-mediated gene delivery.

Contribution

It offers high-resolution observations of DNA-membrane interactions during electroporation and proposes a theoretical model explaining site-specific DNA aggregation.

Findings

DNA complexes form at distinct membrane sites during initial pulses

These sites remain immobile during subsequent pulses

The model explains the efficiency of electro-mediated gene transfer

Abstract

Electroporation is a physical method to induce the uptake of therapeutic drugs and DNA, by eukaryotic cells and tissues. The phenomena behind electro-mediated membrane permeabilization to plasmid DNA have been shown to be significantly more complex than those for small molecules. Small molecules cross the permeabilized membrane by diffusion whereas plasmid DNA first interacts with the electropermeabilized part of the cell surface, forming localized aggregates. The dynamics of this process is still poorly understood because direct observations have been limited to scales of the order of seconds. Here, cells are electropermeabilized in the presence of plasmid DNA and monitored with a temporal resolution of 2 ms. This allows us to show that during the first pulse application, plasmid complexes, or aggregates, start to form at distinct sites on the cell membrane. FRAP measurements show that the positions of these sites are remarkably immobile during the application of further pluses. A theoretical model is proposed to explain the appearance of distinct interaction sites, the quantitative increase in DNA and also their immobility leading to a tentative explanation for the success of electro-mediated gene delivery.