TitleEffect of combined systemic and local morpholino treatment on the spinal muscular atrophy Δ7 mouse model phenotype.
Publication TypeJournal Article
Year of Publication2014
AuthorsNizzardo, M, Simone, C, Salani, S, Ruepp, M-D, Rizzo, F, Ruggieri, M, Zanetta, C, Brajkovic, S, Moulton, HM, Müehlemann, O, Bresolin, N, Comi, GP, Corti, S
JournalClin Ther
Date Published2014 Mar 01
KeywordsAnimals, Behavior, Disease Models, Animal, Injections, Introns, Mice, Mice, Transgenic, Morpholinos, Motor Neurons, Muscular Atrophy, Spinal, Oligonucleotides, Antisense, Phenotype, RNA Splicing, RNA, Small Nuclear, Rotarod Performance Test, Spinal Cord, Survival of Motor Neuron 2 Protein

BACKGROUND: Spinal muscular atrophy (SMA) is a fatal motor neuron disease of childhood that is caused by mutations in the SMN1 gene. Currently, no effective treatment is available. One possible therapeutic approach is the use of antisense oligos (ASOs) to redirect the splicing of the paralogous gene SMN2, thus increasing functional SMN protein production. Various ASOs with different chemical properties are suitable for these applications, including a morpholino oligomer (MO) variant with a particularly excellent safety and efficacy profile.

OBJECTIVE: We investigated a 25-nt MO sequence targeting the negative intronic splicing silencer (ISS-N1) 10 to 34 region.

METHODS: We administered a 25-nt MO sequence against the ISS-N1 region of SMN2 (HSMN2Ex7D[-10-34]) in the SMAΔ7 mouse model and evaluated the effect and neuropathologic phenotype. We tested different concentrations (from 2 to 24 nM) and delivery protocols (intracerebroventricular injection, systemic injection, or both). We evaluated the treatment efficacy regarding SMN levels, survival, neuromuscular phenotype, and neuropathologic features.

RESULTS: We found that a 25-nt MO sequence against the ISS-N1 region of SMN2 (HSMN2Ex7D[-10-34]) exhibited superior efficacy in transgenic SMAΔ7 mice compared with previously described sequences. In our experiments, the combination of local and systemic administration of MO (bare or conjugated to octaguanidine) was the most effective approach for increasing full-length SMN expression, leading to robust improvement in neuropathologic features and survival. Moreover, we found that several small nuclear RNAs were deregulated in SMA mice and that their levels were restored by MO treatment.

CONCLUSION: These results indicate that MO-mediated SMA therapy is efficacious and can result in phenotypic rescue, providing important insights for further development of ASO-based therapeutic strategies in SMA patients.

Alternate JournalClin Ther
PubMed ID24636820
Grant ListGGP09107 / / Telethon / Italy