Long-term Rescue of a Lethal Murine Model of Methylmalonic Acidemia Using Adeno associated Viral Gene Therapy

Organic Acid Research Section, Genetics and Molecular Biology Branch, National Human Genome Research Institute, National Institutes of Health, Bethesda, Maryland 20893, USA.
Molecular Therapy (Impact Factor: 6.23). 10/2009; 18(1):11-6. DOI: 10.1038/mt.2009.247
Source: PubMed


Methylmalonic acidemia (MMA) is an organic acidemia caused by deficient activity of the mitochondrial enzyme methylmalonyl-CoA mutase (MUT). This disorder is associated with lethal metabolic instability and carries a poor prognosis for long-term survival. A murine model of MMA that replicates a severe clinical phenotype was used to examine the efficacy of recombinant adeno-associated virus (rAAV) serotype 8 gene therapy as a treatment for MMA. Lifespan extension, body weight, circulating metabolites, transgene expression, and whole animal propionate oxidation were examined as outcome parameters after gene therapy. One-hundred percent of the untreated Mut(-/-) mice (n = 58) died by day of life (DOL) 72, whereas >95% of the adeno-associated virus-treated Mut(-/-) mice (n = 27) have survived for > or = 1 year. Despite a gradual loss of transgene expression and elevated circulating metabolites in the treated Mut(-/-) mice, the animals are indistinguishable from unaffected control littermates in size and activity levels. These experiments provide the first definitive evidence that gene therapy will have clinical utility in the treatment of MMA and support the development of gene therapy for other organic acidemias.

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Available from: Randy J. Chandler
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    • "Neither the elimination of transgene expression nor the impaired mitochondrial importation and processing of the human MUT protein is suggested by our studies. The fact that circulating metabolite concentrations and in vivo propionate oxidative capacity in the AAV treated Mut −/− mice is almost exactly what we previously observed in studies using AAVs that expressed the murine cDNA provide support for this claim [5] [6]. While the presence of antibodies against MUT was not directly investigated, the prolonged survival after treatment suggests the absence of an immune response. "
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    ABSTRACT: We demonstrate that human methylmalonyl-CoA mutase (MUT), delivered using an AAV serotype 8 vector, rescues the lethal phenotype displayed by mice with MMA and provides long-term phenotypic correction. In addition to defining a lower limit of effective dosing, our studies establish that neither a species barrier to mitochondrial processing nor an apparent immune response to MUT limits the murine model as an experimental platform to test the efficacy of human gene therapy vectors for MMA. Published by Elsevier Inc.
    Full-text · Article · Sep 2012 · Molecular Genetics and Metabolism
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    • "Nonintegrating vectors based on adenovirus or adenoassociated virus (AAV) have shown high transduction efficiency in neonatal gene transfer; however, both vector systems suffer significant loss of transgene expression because of dilution of vector genome during rapid cell proliferation, especially in liver (Wang et al., 2005; Cunningham et al., 2008; Hu et al., 2011). Despite the reduction of transgene expression levels and vector genome copies, therapeutic effects or long-term rescue of neonatal lethality have been demonstrated in several animal models (Daly et al., 2001; Carrillo- Carrasco et al., 2010; Chandler and Venditti, 2010; Yiu et al., 2010; Chandler et al., 2011; Cotugno et al., 2011; Hu et al., 2011). In these cases, expression of the normal gene in a small percentage of stably transduced cells accounts for the clinical effects. "
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    ABSTRACT: For genetic diseases that manifest at a young age with irreversible consequences, early treatment is critical and essential. Neonatal gene therapy has the advantages of achieving therapeutic effects before disease manifestation, a low vector requirement and high vector-to-cell ratio, and a relatively immature immune system. Therapeutic effects or long-term rescue of neonatal lethality have been demonstrated in several animal models. However, vigorous cell proliferation in the newborn stage is a significant challenge for nonintegrating vectors, such as adeno-associated viral (AAV) vector. Slightly delaying the injection age, and readministration at a later time, are two of the alternative strategies to solve this problem. In this study, we demonstrated robust and efficient hepatic gene transfer by self-complementary AAV8 vector in neonatal mice. However, transduction quickly decreased over a few weeks because of vector dilution caused by fast proliferation. Delaying the injection age improved sustained expression, although it also increased neutralizing antibody (NAb) responses to AAV capsid. This approach can be used to treat genetic diseases with slow progression. For genetic diseases with early onset and severe consequences, early treatment is essential. A second injection of vector of a different serotype at a later time may overcome preexisting NAb and achieve sustained therapeutic effects.
    Preview · Article · Nov 2011 · Human gene therapy
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    • "To investigate the potential of viral gene transfer as a treatment for PA, we used the same methodology and vector design previously used in our successful AAV8 MMA gene therapy studies (Chandler and Venditti, 2010). In this report, we establish that AAV8-mediated gene delivery to Pcca –/– mice can provide long-term rescue of the neonatal lethal phenotype, result in hepatic PCCA expression, and significantly reduce the levels of propionyl-CoA-derived metabolites. "
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    ABSTRACT: Propionic acidemia (PA) is an autosomal recessive disorder of metabolism caused by a deficiency of propionyl-coenzyme A carboxylase (PCC). Despite optimal dietary and cofactor therapy, PA patients still suffer from lethal metabolic instability and experience multisystemic complications. A murine model of PA (Pcca(-/-)) of animals that uniformly die within the first 48 hr of life was used to determine the efficacy of adeno-associated viral (AAV) gene transfer as a potential therapy for PA. An AAV serotype 8 (AAV8) vector was engineered to express the human PCCA cDNA and delivered to newborn mice via an intrahepatic injection. Greater than 64% of the Pcca(-/-) mice were rescued after AAV8-mediated gene transfer and survived until day of life 16 or beyond. Western analysis of liver extracts showed that PCC was completely absent from Pcca(-/-) mice but was restored to greater than wild-type levels after AAV gene therapy. The treated Pcca(-/-) mice also exhibited markedly reduced plasma levels of 2-methylcitrate compared with the untreated Pcca(-/-) mice, which indicates significant PCC enzymatic activity was provided by gene transfer. At the time of this report, the oldest treated Pcca(-/-) mice are over 6 months of age. In summary, AAV gene delivery of PCCA effectively rescues Pcca(-/-) mice from neonatal lethality and substantially ameliorates metabolic markers of the disease. These experiments demonstrate a gene transfer approach using AAV8 that might be used as a treatment for PA, a devastating and often lethal disorder desperately in need of new therapeutic options.
    Full-text · Article · Oct 2010 · Human gene therapy
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