title: Tracking in vitro and in vivo siRNA electrotransfer in tumor cells.
abstract: RNA interference-mediated gene silencing offers the potential of targeted inhibition of disease-relevant genes. In vivo delivery of RNAi reagents can be obtained by a variety of approaches. Physical delivery methods appear safer and lack side effects. Electro-permeabilization is one of the non-viral methods successfully used to transfer small interfering RNAs (siRNAs) in vitro and in vivo. A promising approach may be, very little is known about the fundamental processes mediating siRNA transfer. In this study, we have investigated cellular delivery pathways involved in electro-delivery of siRNAs by a direct fluorescence imaging method. An Alexa-labeled siRNA was electro-transferred into murine melanoma cells stably-expressing the enhanced green fluorescent protein (eGFP) target reporter gene. The silencing of eGFP gene expression was quantified by time-lapsed fluorescence microscopy. Fluorescently-labeled siRNAs were found distributed homogeneously in cytoplasm 48 hours after electro-transfer, apparently by diffusion. Furthermore, siRNAs showed homogeneous distribution in vivo 48 hrs after intra-tumoral injection followed by electro- permeabilization. Histological fluorescence microscopy showed that siRNAs were mostly localized in the cytoplasm. Overall, this study shows that electro-permeabilization facilitates cytoplasmic distribution of siRNA, both in cultured cells and in vivo. This method offers a potential therapeutic tool to facilitate direct siRNA penetration into solid tumors.
authors.affiliation: IPBS CNRS (UMR 5089 Université de Toulouse III, CNRS), 205 Route de Narbonne, 31077 Toulouse France.
authors.forename: Aurelie
authors.initials: A
authors.lastname: Paganin-Gioanni
authors.forename: Elisabeth
authors.initials: E
authors.lastname: Bellard
authors.forename: Bettina
authors.initials: B
authors.lastname: Couderc
authors.forename: Justin
authors.initials: J
authors.lastname: Teissié
authors.forename: Muriel
authors.initials: M
authors.lastname: Golzio