Between defence and delivery: the DNA sensing response to gene electrotransfer

Gene therapy has emerged as a transformative biomedical approach, offering new therapeutic possibilities from many so far uncurable diseases through the introduction of recombinant nucleic acids into target cells. Among non-viral delivery techniques, gene electrotransfer (GET) has become one of the frequently applied methods in clinical trials. It is based on the application of short, high-intensity electric pulses that transiently permeabilize cell membranes and enable the efficient transfer of plasmid DNA or other types of recombinant nucleic acids into various cell types. Beyond its role in gene delivery, GET can trigger complex cellular responses, as the introduced DNA interacts with intracellular DNA sensing pathways involved in innate immunity and inflammation. These responses can influence the therapeutic outcome - either by enhancing antitumour and vaccine-related immune activation or by reducing transfection efficiency when excessive inflammation or cell death occur. Our experimental findings in tumour, muscle, and skin models have shown that even non-coding plasmid DNA delivered by GET can induce local immune stimulation and tissue-specific inflammatory signaling, suggesting that the delivered DNA itself contributes to therapeutic efficacy.

The dual nature of cellular responses following plasmid DNA GET represents both an opportunity and a challenge. Controlled activation of innate immunity can be harnessed to amplify antitumour or vaccine efficacy, while excessive responses may hinder applications requiring cell survival and sustained expression. Understanding these mechanisms enables the rational optimization of GET parameters and plasmid vector design to fully exploit the adjuvant effect or reduce the off-target effect of DNA sensing after GET, based on the desired application.