Résumé :
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Duchene Muscular Dystrophy (DMD) is a severe muscle disorder caused by mutations in the dystrophin gene. The efficacy of antisense oligonucleotide (AO)-mediated exon skipping for the restoration of dystrophin has been established in animal models and in DMD patients. However there remain significant limitations to this therapeutic approach due to the lack of effective systemic AO delivery to target tissues of muscle and heart. Here we investigate systemic tissue-specific AO delivery by testing AOs directly conjugated to cell penetrating peptides (CPPs) alone or in combination with tissue-specific homing peptides (e.g. muscle-specific peptide, MSP). Morpholino (PMO) chemistry AOs were directly conjugated to CPPs alone or in combination with homing peptides and evaluated in mdx mice following systemic delivery. Effective exon skipping and dystrophin expression were induced in body-wide skeletal muscles at extremely low AO doses of 3mg/kg and also in heart. This is the first time that targeted AO delivery to muscle and successful body-wide restoration of dystrophin expression have been achieved at such low AO doses. In parallel we also report the discovery and characterization of a novel delivery formulation which facilitates AO uptake in muscle. A series of studies have shown that this delivery formulation enhances the delivery of AOs of different chemistries (e.g. 2-OMeRNA, PNA and PMO), depends on the activity of specific muscle membrane transporters, and that it induces significant restoration of dystrophin expression in muscle compared with commonly used delivery formulations. In summary, we report data demonstrating the potential of tissue-specific homing peptides, CPPs and novel delivery formulations for the targeted restoration of dystrophin in DMD.
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