O.14 Biocompatible nanoparticles as slow-release delivery system of 2′ OMePS AON administered both intraperitoneally and orally in the mdx mice: dystrophin rescue and nanoparticles biodistribution

We recently demonstrated that lower doses of 2′-O-methyl-phosphorothioate antisense oligoribonucleotides (AONs) adsorbed to cationic core–shell nanoparticles (NPs) induce widespread dystrophin restoration, even 45 days after intra-peritoneal (I.P) treatment, in mdx mice. Here we describe persistent, albeit low, levels of AON-induced skipped transcript in muscles from mdx mice sacrificed three months after NP-AON treatment, associated with well-maintained dystrophin expression in skeletal muscles, detectable by immunostaining and western blotting. We also administered by oral route NP-AON in mdx mice: rescued dystrophin protein is detectable in intestinal smooth muscle by immunofluorescence and western blot analysis. Nanoparticles labeled with IR-Dye (Li-COR Biosciences) were used to evaluate biodistribution in mdx mice injected I.P or orally, by using Odyssey Imager–Li-COR Biosciences. Twenty four hours after I.P injection the NPs are still in the peritoneal cavity. After longer time the peritoneal cavity becomes less fluorescent, while the fluorescence diffuses widely in all the body, especially in lymphatic tissues (spleen) suggesting a body distribution via lymphatic vessels. Fluorescence is detectable up to 22 days. The time course of NP-IR-Dye after oral administration demonstrates the persistence of NPs in intestinal lumen for at least 48 h. During this time some fluorescence is also visible outside from the intestine, as in the spleen. The Telethon Italy Grant GGPO9093 (to AF, PB, ML, MNM) is acknowledged.