Effect of Combined Systemic and Local Morpholino Treatment on the Spinal Muscular Atrophy 螖7 Mouse Model Phenotype

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• 作者：Monica Nizzardo ; PhD¹ ; Chiara Simone ; PhD¹ ; Sabrina Salani ; PhD¹ ; Marc-David Ruepp ; PhD² ; Federica Rizzo ; PhD¹ ; Margherita Ruggieri ; PhD¹ ; Chiara Zanetta ; MD¹ ; Simona Brajkovic ; MD¹ ; Hong M. Moulton ; PhD³ ; Oliver Mü ; ehlemann ; PhD² ; Nereo Bresolin ; MD¹ ; ⁴ ; Giacomo P. Comi ; MD¹ ; Stefania Corti ; MD ; PhD¹ ; ^* ; ^{stefania.corti@unimi.it" class="auth_mail}
• 关键词：morpholino oligomer ; SMA螖7 mice ; spinal muscular atrophy ; survival motor neuron ; therapy
• 刊名：Clinical Therapeutics
• 出版年：1 March, 2014
• 年：2014
• 卷：36
• 期：3
• 页码：340-356.e5
• 全文大小：3342 K

文摘

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 SMA螖7 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 SMA螖7 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.