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1022. Efficient Dystrophin Production in Response to Local and Systemic Administration of Morpholino Antisense Oligonucleotides in the Mdx Mouse

2006; Elsevier BV; Volume: 13; Linguagem: Inglês

10.1016/j.ymthe.2006.08.1117

1525-0024

Ian R. Graham, Francesca C. Thorogood, Helen Foster, George Dickson,

Virus-based gene therapy research

Duchenne muscular dystrophy (DMD) is an X-linked recessive inherited disease that affects 1 in 3,500 male births. It is characterised by severe muscle wasting and muscle degeneration. Affected patients are frequently wheelchair-bound prior to 12 years and usually die in their late teens or early twenties as a result of respiratory or cardiac failure. DMD arises as a result of frameshift mutations (often gross deletions) in the gene encoding dystrophin, a 427kDa protein of the muscle sarcolemma that functions as a molecular scaffold connecting the intracellular actin cytoskeleton with the extracellular matrix. Such mutations result in a complete absence of dystrophin protein and lead to the DMD phenotype, for which there is currently no cure. Gene therapy approaches have traditionally been based on gene augmentation strategies, in which a functional copy of the dystrophin cDNA, or truncations thereof, has been introduced on viral or plasmid vectors. In an alternative strategy, we and others have been developing the use of antisense oligonucleotides (AO) to induce the exclusion of specific exons during the splicing of dystrophin pre- mRNA. We have used the mdx mouse, a naturally-occurring model of DMD carrying a stop codon in exon 23 of the dystrophin gene, to demonstrate that exclusion (skipping) of exon 23 in response to AO does indeed result in de novo production of dystrophin by modulation of the splicing pathway. Recent advances in oligonucleotide chemistry and design have allowed us to compare the efficiency of delivery and bioactivity of AOs based on morpholino phosphorodiamidate backbones with those of the previous 2′-O-methyl chemistry. Again using the mdx mouse, we have performed dose-response and time-course studies of morpholino AOs targeted to exon 23, by both intramuscular and intravenous delivery. In this way, we have demonstrated widespread and efficient AO-induced dystrophin production by both delivery routes, in a manner which shows AO therapy to be a potentially viable treatment for DMD in a clinical setting.