Dystrophin expression in the mdx mouse after localised and systemic administration of a morpholino antisense oligonucleotide

Abstract

The stability of the morpholino structural type, and the fact that it can be delivered to muscle in the absence of a delivery reagent, render this compound eminently suitable for consideration for therapeutic exon skipping to address dystrophin mutations.

Antisense-mediated exon skipping: A versatile tool with therapeutic and research applications

“…Morpholinos have gained attention for DMD exon skipping since this chemistry is taken up at higher levels by the muscle (Sazani et al 2002). Systemic delivery of morpholino in the mdx mouse was indeed more efficient than the 29-O-methyl phosphorothioate counterpart (Alter et al 2006;Fletcher et al 2006; H.A. Heemskerk, G.-J.B. van Ommen, S. de Kimpe, P. van Kuik, J.C.T.…”

Cationic polyelectrolyte-mediated delivery of antisense morpholino oligonucleotides for exon-skipping in vitro and in mdx mice

“…Of the synthetic oligonucleotide chemistries, phosphorodiamidate morpholino oligomer (PMO) is most widely used for exon-skipping in the dystrophin gene currently being applied in clinical trials. [11][12][13][14][15] PMO, as a synthetic mimic of nucleic acid, has deoxyribose rings replaced with morpholino rings and linked through phosphorodiamidate inter-subunits, making it neutral under physiological conditions. It has exhibited excellent stability, and lower toxicity compared with its counterparts, such as 2′-O-methyl-phosphorothioate RNA and peptide nucleic acid.…”

Comparative Analysis of Antisense Oligonucleotide Sequences for Targeted Skipping of Exon 51 During Dystrophin Pre-mRNA Splicing in Human Muscle

“…In DMD research, the potential clinical use of AOs has evolved from studies in vitro on cultured mdx mouse muscle cells (Dunckley et al, 1998;Mann et al, 2001Mann et al, , 2002 and human DMD muscle cells (van Deutekom et al, 2001;Aartsma-Rus et al, 2002, 2004a to in vivo studies in mdx and GRMD (golden retriever muscular dystrophy) animal models (Lu et al, 2003(Lu et al, , 2005Fletcher et al, 2006;McClorey et al, 2006b) (Table 1). Direct in vivo AO-induced exon skipping in humans, however, has yet to be demonstrated and this proof of principle, along with clinical safety, is the crucial aspect of initial clinical studies.…”

“…The majority of the AO work undertaken on cultured cells has been performed with 2-OMe AOs, as this chemistry is readily available and, more importantly, allows efficient cell transfection as a cationic lipoplex preparation (Summerton and Weller, 1997;Fletcher et al, 2006). Although PMOs appear to be more efficient after direct administration to tissues in the mdx mouse than the equivalent 2-OMe AO , their poor uptake in vitro limits the approaches that can be used to refine AO design.…”