Induction of Dystrophin Expression by Exon Skipping in mdx Mice Following Intramuscular Injection of Antisense Oligonucleotides Complexed with PEG-PEI Copolymers

Jason H. Williams, Shashank R. Sirsi, Daniel R. Latta, Gordon J. Lutz

Research output: Contribution to journalArticle

35 Scopus citations


Antisense oligonucleotides (AOs) with 2-O-methyl modifications can circumvent dystrophin mutations via exon skipping and, it is hoped, can become drugs for treatment of Duchenne muscular dystrophy (DMD). However, AO-based approaches are hindered by a lack of effective carriers to facilitate delivery of AOs to myonuclei. We examined whether copolymers composed of cationic poly(ethylene imine) (PEI) and polyethylene glycol (PEG) can enhance AO transfection in skeletal muscle of mdx mice. Single intramuscular injections of AO complexed with low Mw PEI2000(PEG550) copolymers into TA muscles of mdx mice resulted in widespread distribution of dystrophin-positive fibers at 3 weeks after injection, with no apparent cytotoxicity. Overall, injections of these low Mw polyplexes, which formed 250-nm aggregate particles, resulted in about sixfold more dystrophin-positive fibers than AO alone. Western analysis confirmed the dystrophin expression in these muscles. Surprisingly, injections of AO complexed with high Mw PEI25000(PEG5000) copolymers, which formed smaller nonaggregated particles, produced about threefold fewer dystrophin-positive fibers than injections of the low Mw polyplexes. We conclude that low Mw PEI2000(PEG550) copolymers function as high-capacity, nontoxic AO carriers suitable for in vivo transfection of skeletal muscle and are promising compounds for potential use in molecular therapy of DMD.

Original languageEnglish (US)
Pages (from-to)88-96
Number of pages9
JournalMolecular Therapy
Issue number1
StatePublished - Jul 1 2006



  • Duchenne muscular dystrophy
  • antisense oligonucleotides
  • dystrophin
  • exon skipping
  • mdx mouse
  • skeletal muscle

ASJC Scopus subject areas

  • Molecular Medicine
  • Molecular Biology
  • Genetics
  • Pharmacology
  • Drug Discovery

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