Long-term rescue of dystrophin expression and improvement in muscle pathology and function in dystrophic mdx mice by peptide-conjugated morpholino.
Exon skipping is capable of correcting frameshift and nonsense mutations in Duchenne muscular dystrophy. Phase 2 clinical trials in the United Kingdom and the Netherlands have reported induction of dystrophin expression in muscle of Duchenne muscular dystrophy patients by systemic administration of both phosphorodiamidate morpholino oligomers (PMO) and 2'-O-methyl phosphorothioate. Peptide-conjugated phosphorodiamidate morpholino offers significantly higher efficiency than phosphorodiamidate morpholino, with the ability to induce near-normal levels of dystrophin, and restores function in both skeletal and cardiac muscle. We examined 1-year systemic efficacy of peptide-conjugated phosphorodiamidate morpholino targeting exon 23 in dystrophic mdx mice. The LD(50) of peptide-conjugated phosphorodiamidate morpholino was determined to be approximately 85 mg/kg. The half-life of dystrophin expression was approximately 2 months in skeletal muscle, but shorter in cardiac muscle. Biweekly injection of 6 mg/kg peptide-conjugated phosphorodiamidate morpholino produced >20% dystrophin expression in all skeletal muscles and ≤5% in cardiac muscle, with improvement in muscle function and pathology and reduction in levels of serum creatine kinase. Monthly injections of 30 mg/kg peptide-conjugated phosphorodiamidate morpholino restored dystrophin to >50% normal levels in skeletal muscle, and 15% in cardiac muscle. This was associated with greatly reduced serum creatine kinase levels, near-normal histology, and functional improvement of skeletal muscle. Our results demonstrate for the first time that regular 1-year administration of peptide-conjugated phosphorodiamidate morpholino can be safely applied to achieve significant therapeutic effects in an animal model.
McColl-Lockwood Laboratory for Muscular Dystrophy Research, Neuromuscular/ALS Center, Department of Neurology, Carolinas Medical Center, Charlotte, North Carolina, USA. bo.wu@carolinashealthcare.org
Bo
B
Wu
Peijuan
P
Lu
Caryn
C
Cloer
Mona
M
Shaban
Snimar
S
Grewal
Stephanie
S
Milazi
Sapana N
SN
Shah
Hong M
HM
Moulton
Qi Long
QL
Lu
D061605:Administration, Intravenous; D000818:Animals; D004334:Drug Administration Schedule; D016189:Dystrophin / Q000378:metabolism*; D006207:Half-Life; D007928:Lethal Dose 50; D051379:Mice; D008810:Mice, Inbred C57BL; D018101:Mice, Inbred mdx; D060172:Morpholinos / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D009132:Muscles / Q000187:drug effects / Q000473:pathology* / Q000503:physiopathology; D009137:Muscular Dystrophy, Animal / Q000097:blood / Q000188:drug therapy* / Q000503:physiopathology*; D010455:Peptides / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use*; D020127:Recovery of Function / Q000502:physiology*; D013997:Time Factors
D016189:Dystrophin; D060172:Morpholinos; D010455:Peptides