T.P.22 Nanoparticles as delivery systems for antisense oligoribonucleotides: Biodistribution studies and definition of the release kinetic in treated mdx mice

Abstract

Abstract We have tested different types of polymeric cationic core–shell nanoparticles (NPs) for delivering 2- O -methyl-phosphorothioate antisense oligoribonucleotides (AONs), in mdx mice. Both T1 and ZM2 NP bind and convey AONs: intraperitoneal (IP) injections of low doses (52.5 mg/kg) of NP–AON complex restored dystrophin protein synthesis in skeletal and cardiac muscles, allowing protein localization in up to 40% of muscle fibers with skipping level up to 20%. We have tested in vivo (mdx) the tissue biodistribution and elimination timing of NPs by Odyssey, using an infrared dye conjugated ZM2 NP. Administration mode was both IP and oral. Elimination by feces was up to 80% after 22 days of a single injection treatment in mdx treated by intraperitoneal doses, and close to 100% in those treated orally after 72 h of a single dose treatment. Evaluation of NP biodistribution, measured by Odyssey, in organs/tissues cryosections of sacrificed mdx revealed an intense positivity of labeled NP in muscles, heart, intestine, and all organs. We also demonstrated that NP–AON formulations passes the gastric barrier and induce dystrophin rescue in the intestinal smooth muscles as well as in the diaphragm. However the intense positivity at biodistribution of NPs in the heart (and skeletal muscles) conflicts with the relatively low efficacy of the compound in terms of skipping and dystrophin rescue. We are therefore performing ELISA assay to dose the antisense in the treated mice muscles in order to define the release kinetic of the AON from NPs. This is crucial in order to further proceed with other NP studies.