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Wong SH, McClaren BJ, Archibald AD, Weeks A, Langmaid T, Ryan MM, Kornberg A, Metcalfe SA. A mixed methods study of age at diagnosis and diagnostic odyssey for Duchenne muscular dystrophy. Eur J Hum Genet 2015; 23:1294-300. [PMID: 25626706 DOI: 10.1038/ejhg.2014.301] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2014] [Revised: 12/05/2014] [Accepted: 12/16/2014] [Indexed: 01/15/2023] Open
Abstract
The delayed diagnosis of Duchenne muscular dystrophy (DMD) may be an ongoing problem internationally. We aimed to ascertain age at diagnosis and explore parents' experiences of the diagnosis of DMD in Australia. Using mixed methods, data were collected from laboratory and clinical record audits of testing for DMD in Victoria and Tasmania, interviews and a national survey of parents regarding their experiences from first noticing symptoms to receiving a diagnosis. The audits revealed that the median age at diagnosis for DMD was 5 years (n=49 during 2005-2010); this age had not changed substantially over this period. Fourteen parents interviewed reported age at diagnosis ranging from 2 to 8 years with a 6 month to 4 year delay between initial concerns about their child's development and receiving the DMD diagnosis. Sixty-two survey respondents reported the median age at diagnosis was 3 years and 9 months, while the median age when symptoms were noticed was 2 years and 9 months. Parents experienced many emotions in their search for a diagnosis and consulted with a wide range of health professionals. Half the survey respondents felt that their child could have been diagnosed earlier. Despite advances in testing technologies and increasing awareness of DMD, the age at diagnosis has remained constant in Australia. This mixed methods study shows that this diagnostic delay continues to have a negative impact on parents' experiences, places families at risk of having a second affected child and may have a deleterious effect on affected children's treatment.
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Affiliation(s)
- Siaw H Wong
- Murdoch Childrens Research Institute, Parkville, VIC, Australia.,Department of Paediatrics, The University of Melbourne, Parkville, VIC, Australia
| | | | - Alison Dalton Archibald
- Murdoch Childrens Research Institute, Parkville, VIC, Australia.,Department of Paediatrics, The University of Melbourne, Parkville, VIC, Australia.,Victorian Clinical Genetics Services, Parkville, VIC, Australia
| | - Alice Weeks
- Murdoch Childrens Research Institute, Parkville, VIC, Australia
| | - Tess Langmaid
- Murdoch Childrens Research Institute, Parkville, VIC, Australia
| | - Monique M Ryan
- Murdoch Childrens Research Institute, Parkville, VIC, Australia.,Department of Paediatrics, The University of Melbourne, Parkville, VIC, Australia.,Department of Neurology, Royal Children's Hospital, Parkville, VIC, Australia
| | - Andrew Kornberg
- Murdoch Childrens Research Institute, Parkville, VIC, Australia.,Department of Paediatrics, The University of Melbourne, Parkville, VIC, Australia.,Department of Neurology, Royal Children's Hospital, Parkville, VIC, Australia
| | - Sylvia A Metcalfe
- Murdoch Childrens Research Institute, Parkville, VIC, Australia.,Department of Paediatrics, The University of Melbourne, Parkville, VIC, Australia
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Hashim HZ, Che Abdullah ST, Wan Sulaiman WA, Hoo FK, Basri H. Hunting for a cure: The therapeutic potential of gene therapy in Duchenne muscular dystrophy. Tzu Chi Med J 2014. [DOI: 10.1016/j.tcmj.2014.02.002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
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Buck NE, Wood LR, Hamilton NJ, Bennett MJ, Peters HL. Treatment of a methylmalonyl-CoA mutase stopcodon mutation. Biochem Biophys Res Commun 2012; 427:753-7. [PMID: 23041189 DOI: 10.1016/j.bbrc.2012.09.133] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/26/2012] [Accepted: 09/27/2012] [Indexed: 12/16/2022]
Abstract
There are limited treatment options for the metabolic disorder methylmalonic aciduria. The disorder can be caused by nonsense mutations within the methylmalonyl-CoA mutase gene, resulting in the production of a truncated protein with little or no catalytic activity. We used a genomic reporter assay and mouse primary cell lines which carry a stop-codon mutation in the human methylmalonyl-CoA mutase gene to test the effects of gentamicin and PTC124 for stop-codon read-through potential. Fibroblast cell lines were established from methylmalonic aciduria knockout-stop codon mice. Addition of gentamicin to the culture medium caused a 1.5- to 2-fold increase in mRNA expression of the human methylmalonyl-CoA mutase gene. Without treatment the cells contained 19% of the normal levels of methylmalonyl-CoA mutase enzyme activity which increased to 32% with treatment, suggesting a functional improvement. Treatment with PTC124 increased the amount of human methylmalonyl-CoA mutase gene mRNA by 1.6±0.3-fold and a trend suggesting increased enzyme activity. The genomic reporter assay, BAC_MMA(∗)EGFP, expresses enhanced green fluorescent protein when read-through of the stop codon occurs. Using flow cytometry, RT-real-time PCR and enzyme assay, read-through was measured. Treatment with PTC124 at 20μmol/L resulted in a significant increase in enhanced green fluorescent protein, a 2-fold increase in mRNA expression and a trend to a slight increase in enzyme activity. The clinical relevance of these effects may be tested in mouse models of MMA carrying nonsense mutations in the methylmalonyl-CoA mutase gene. Pharmacological approaches have the advantage of providing a broader effect on multiple tissues, which will benefit many different disorders with similar nonsense mutations.
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Affiliation(s)
- Nicole E Buck
- Metabolic Research, Murdoch Childrens Research Institute, The University of Melbourne Department of Paediatrics, Royal Children's Hospital, Flemington Road, Parkville, Victoria 3052, Australia.
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Mammalian models of Duchenne Muscular Dystrophy: pathological characteristics and therapeutic applications. J Biomed Biotechnol 2011; 2011:184393. [PMID: 21274260 PMCID: PMC3022202 DOI: 10.1155/2011/184393] [Citation(s) in RCA: 69] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2010] [Accepted: 12/19/2010] [Indexed: 11/23/2022] Open
Abstract
Duchenne muscular dystrophy (DMD) is a devastating X-linked muscle disorder characterized by muscle wasting which is caused by mutations in the DMD gene. The DMD gene encodes the sarcolemmal protein dystrophin, and loss of dystrophin causes muscle degeneration and necrosis. Thus far, therapies for this disorder are unavailable. However, various therapeutic trials based on gene therapy, exon skipping, cell therapy, read through therapy, or pharmaceutical agents have been conducted extensively. In the development of therapy as well as elucidation of pathogenesis in DMD, appropriate animal models are needed. Various animal models of DMD have been identified, and mammalian (murine, canine, and feline) models are indispensable for the examination of the mechanisms of pathogenesis and the development of therapies. Here, we review the pathological features of DMD and therapeutic applications, especially of exon skipping using antisense oligonucleotides and gene therapies using viral vectors in murine and canine models of DMD.
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Albesa M, Ogrodnik J, Rougier JS, Abriel H. Regulation of the cardiac sodium channel Nav1.5 by utrophin in dystrophin-deficient mice. Cardiovasc Res 2010; 89:320-8. [DOI: 10.1093/cvr/cvq326] [Citation(s) in RCA: 36] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
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Goyenvalle A, Babbs A, Powell D, Kole R, Fletcher S, Wilton SD, Davies KE. Prevention of dystrophic pathology in severely affected dystrophin/utrophin-deficient mice by morpholino-oligomer-mediated exon-skipping. Mol Ther 2009; 18:198-205. [PMID: 19844193 DOI: 10.1038/mt.2009.248] [Citation(s) in RCA: 88] [Impact Index Per Article: 5.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Duchenne muscular dystrophy (DMD) is a severe neuromuscular disorder caused by mutations in the dystrophin gene that result in the absence of functional protein. Antisense-mediated exon-skipping is one of the most promising approaches for the treatment of DMD because of its capacity to correct the reading frame and restore dystrophin expression, which has been demonstrated in vitro and in vivo. In particular, peptide-conjugated phosphorodiamidate morpholino oligomers (PPMOs) have recently been shown to induce widespread high levels of dystrophin expression in the mdx mouse model. Here, we report the efficiency of the PPMO-mediated exon-skipping approach in the utrophin/dystrophin double-knockout mouse (dKO) mouse, which is a much more severe and progressive mouse model of DMD. Repeated intraperitoneal (i.p.) injections of a PPMO targeted to exon 23 of dystrophin pre-mRNA in dKO mice induce a near-normal level of dystrophin expression in all muscles examined, except for the cardiac muscle, resulting in a considerable improvement of their muscle function and dystrophic pathology. These findings suggest great potential for PPMOs in systemic treatment of the DMD phenotype.
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Affiliation(s)
- Aurélie Goyenvalle
- MRC Functional Genomics Unit, Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK
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Buck NE, Wood L, Hu R, Peters HL. Stop codon read-through of a methylmalonic aciduria mutation. Mol Genet Metab 2009; 97:244-9. [PMID: 19427250 DOI: 10.1016/j.ymgme.2009.04.004] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 02/08/2009] [Revised: 04/02/2009] [Accepted: 04/02/2009] [Indexed: 11/19/2022]
Abstract
A stop codon defect in methylmalonyl-CoA mutase (resulting in a truncated unstable protein) accounts for up to 14% of mutations identified as causes of Methylmalonic aciduria. There are currently limited treatment regimes for patients with this inherited condition. We aimed to investigate the use of stop codon read-through drugs in a genomic reporter assay cell line with a defect in the mutase gene. A single C-T base change was introduced into exon 6 of the human MUT sequence in the BAC clone RP11-463L20 resulting in an arginine residue being replaced with a TGA stop codon. An enhanced green fluorescent protein reporter gene was introduced in-frame with exon 13 of the MUT gene. The construct was transfected into HeLa cells to produce the genomic reporter assay cell line. To test the suppression of nonsense mutations, cells were incubated in the presence of different compounds for a period of 72 h then analysed by flow cytometry. Treatment of the cells with gentamicin resulted in a 1.6-fold increase in reporter protein, whilst G418 treatment resulted in no change, however the two drugs together acted synergistically to increase the production of methylmalonyl-CoA mutase 2.0-fold (confirmed by mRNA, flow cytometry and enzyme activity). Zidovudine, adefovir and cisplatin were also found to have some activity in the stop codon read-through genomic reporter assay. These results encourage further testing of compounds as well as follow up animal studies. This is the first study to demonstrate the use of stop codon read-through drugs for the potential treatment of Methylmalonic aciduria.
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Affiliation(s)
- Nicole E Buck
- Cell & Gene Therapy Group, Murdoch Childrens Research Institute, Department of Paediatrics, University of Melbourne, Royal Children's Hospital, Parkville, Vic. 3052, Australia
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Abstract
Duchenne muscular dystrophy (DMD) is a lethal muscle disorder caused by mutations in the DMD gene for which no mutation-targeted therapy has been available thus far. However, exon-skipping mediated by antisense oligonucleotides (AOs), which are short single-strand DNAs, has considerable potential for DMD therapy, and clinical trials in DMD patients are currently underway. This exon-skipping therapy changes an out-of-frame mutation into an in-frame mutation, aiming at conversion of a severe DMD phenotype into a mild phenotype by restoration of truncated dystrophin expression. Recently, stable and less-toxic AOs have been developed, and their higher efficacy was confirmed in mice and dog models of DMD. In this review, we briefly summarize the genetic basis of DMD and the potential and perspectives of exon skipping as a promising therapy for this disease.
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Affiliation(s)
- Akinori Nakamura
- Department of Molecular Therapy, National Institute of Neuroscience, National Center of Neurology and Psychiatry (NCNP), Kodaira, Tokyo, Japan
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Matsumura CY, Pertille A, Albuquerque TC, Santo Neto H, Marques MJ. Diltiazem and verapamil protect dystrophin-deficient muscle fibers ofMDXmice from degeneration: A potential role in calcium buffering and sarcolemmal stability. Muscle Nerve 2009; 39:167-76. [DOI: 10.1002/mus.21188] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
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10
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Multiplicity of experimental approaches to therapy for genetic muscle diseases and necessity for population screening. J Muscle Res Cell Motil 2008; 29:247-52. [PMID: 19115047 DOI: 10.1007/s10974-008-9158-5] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/24/2008] [Accepted: 12/03/2008] [Indexed: 12/17/2022]
Abstract
Currently a multiplicity of experimental approaches to therapy for genetic muscle diseases is being investigated. These include replacement of the missing gene, manipulation of the gene message, repair of the mutation, upregulation of an alternative gene and pharmacological interventions targeting a number of systems. A number of these approaches are in current clinical trials. There is considerable anticipation that perhaps more than one of the approaches will finally prove of clinical benefit, but there are many voices of caution. No matter which approaches might ultimately prove effective, there is a consensus that for most benefit to the patients it will be necessary to start treatment as early as possible. A consensus is also developing that the only way to do this is to implement population-based newborn screening to identify affected children shortly after birth. Population-based newborn screening is currently practised in very few places in the world and it brings with it implications for prevention rather than cure of genetic muscle diseases.
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A highly stable and nonintegrated human artificial chromosome (HAC) containing the 2.4 Mb entire human dystrophin gene. Mol Ther 2008; 17:309-17. [PMID: 19034264 DOI: 10.1038/mt.2008.253] [Citation(s) in RCA: 87] [Impact Index Per Article: 5.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022] Open
Abstract
Episomal vector with the capacity to deliver a large gene containing all the critical regulatory elements is ideal for gene therapy. Human artificial chromosomes (HACs) have the capacity to deliver an extremely large genetic region to host cells without integration into the host genome, thus preventing possible insertional mutagenesis and genomic instability. Duchenne muscular dystrophy (DMD) is caused by mutation in the extremely large dystrophin gene (2.4 Mb). We herein report the development of a HAC vector containing the entire human dystrophin gene (DYS-HAC) that is stably maintained in mice and human immortalized mesenchymal stem cells (hiMSCs). The DYS-HAC was transferred to mouse embryonic stem (ES) cells, and isoforms of the DYS-HAC-derived human dystrophin in the chimeric mice generated from the ES cells were correctly expressed in tissue-specific manner. Thus, this HAC vector containing the entire dystrophin gene with its native regulatory elements is expected to be extremely useful for future gene and cell therapies of DMD.
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Li B, Lin M, Tang Y, Wang B, Wang JHC. A novel functional assessment of the differentiation of micropatterned muscle cells. J Biomech 2008; 41:3349-53. [PMID: 19007933 DOI: 10.1016/j.jbiomech.2008.09.025] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2008] [Revised: 09/25/2008] [Accepted: 09/26/2008] [Indexed: 11/20/2022]
Abstract
Duchenne muscular dystrophy (DMD) is a lethal disease characterized by rapid, progressive atrophy of muscle tissues. Timely screening of therapeutic interventions is necessary for the development of effective treatment approaches for DMD. We have developed an in vitro model using a combination of micropatterning of C2C12 skeletal muscle cells and cell traction force microscopy (CTFM). In this model, C2C12 cells were micropatterned on a highly elongated adhesive island such that the cells assumed a shape typical of a myotube. During differentiation, these cells gradually fused together and began expressing dystrophin, a structural protein of myotubes, meanwhile, their contractile forces, represented by cell traction forces, continually increased until the myotubes reached maturation. In addition, the high-degree alignment of cells favored myotube differentiation and dystrophin expression. Since the fundamental structural unit of muscle tissue is myofiber, which is responsible for muscle contraction, such a technology that can directly quantify the contractile forces of the myotube, a precursor of myofiber, may constitute a fast and efficient screening approach for DMD therapies.
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Affiliation(s)
- Bin Li
- MechanoBiology Laboratory, Department of Orthopaedic Surgery, University of Pittsburgh School of Medicine, 210 Lothrop Street, BST, E1640, Pittsburgh, PA 15213, USA
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Dynamics of co-transcriptional pre-mRNA folding influences the induction of dystrophin exon skipping by antisense oligonucleotides. PLoS One 2008; 3:e1844. [PMID: 18365002 PMCID: PMC2267000 DOI: 10.1371/journal.pone.0001844] [Citation(s) in RCA: 30] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/21/2007] [Accepted: 02/08/2008] [Indexed: 11/19/2022] Open
Abstract
Antisense oligonucleotides (AONs) mediated exon skipping offers potential therapy for Duchenne muscular dystrophy. However, the identification of effective AON target sites remains unsatisfactory for lack of a precise method to predict their binding accessibility. This study demonstrates the importance of co-transcriptional pre-mRNA folding in determining the accessibility of AON target sites for AON induction of selective exon skipping in DMD. Because transcription and splicing occur in tandem, AONs must bind to their target sites before splicing factors. Furthermore, co-transcriptional pre-mRNA folding forms transient secondary structures, which redistributes accessible binding sites. In our analysis, to approximate transcription elongation, a “window of analysis” that included the entire targeted exon was shifted one nucleotide at a time along the pre-mRNA. Possible co-transcriptional secondary structures were predicted using the sequence in each step of transcriptional analysis. A nucleotide was considered “engaged” if it formed a complementary base pairing in all predicted secondary structures of a particular step. Correlation of frequency and localisation of engaged nucleotides in AON target sites accounted for the performance (efficacy and efficiency) of 94% of 176 previously reported AONs. Four novel insights are inferred: (1) the lowest frequencies of engaged nucleotides are associated with the most efficient AONs; (2) engaged nucleotides at 3′ or 5′ ends of the target site attenuate AON performance more than at other sites; (3) the performance of longer AONs is less attenuated by engaged nucleotides at 3′ or 5′ ends of the target site compared to shorter AONs; (4) engaged nucleotides at 3′ end of a short target site attenuates AON efficiency more than at 5′ end.
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Marques MJ, Ventura Machado R, Minatel E, Santo Neto H. Disodium cromoglycate protects dystrophin-deficient muscle fibers from leakiness. Muscle Nerve 2008; 37:61-7. [PMID: 17724738 DOI: 10.1002/mus.20892] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
In dystrophin-deficient fibers of mdx mice and in Duchenne dystrophy, the lack of dystrophin leads to sarcolemma breakdown and muscle degeneration. We verified that cromolyn, a mast-cell stabilizer agent, stabilized dystrophic muscle fibers using Evans blue dye as a marker of sarcolemma leakiness. Mdx mice (n=8; 14 days of age) received daily intraperitoneal injections of cromolyn (50 mg/kg body weight) for 15 days. Untreated mdx mice (n=8) were injected with saline. Cryostat cross-sections of the sternomastoid, tibialis anterior, and diaphragm muscles were stained with hematoxylin and eosin. Cromolyn dramatically reduced Evans blue dye-positive fibers in all muscles (P<0.05; Student's t-test) and led to a significant increase in the percentage of fibers with peripheral nuclei. This study supports the protective effects of cromolyn in dystrophic muscles and further indicates its action against muscle fiber leakiness in muscles that are differently affected by the lack of dystrophin.
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MESH Headings
- Animals
- Anti-Asthmatic Agents/pharmacology
- Anti-Asthmatic Agents/therapeutic use
- Cell Membrane Permeability/drug effects
- Cell Membrane Permeability/physiology
- Cromolyn Sodium/pharmacology
- Cromolyn Sodium/therapeutic use
- Disease Models, Animal
- Dystrophin/deficiency
- Dystrophin/genetics
- Female
- Ion Channels/drug effects
- Ion Channels/genetics
- Ion Channels/metabolism
- Ions/metabolism
- Male
- Mast Cells/drug effects
- Mast Cells/immunology
- Mice
- Mice, Inbred mdx
- Muscle Fibers, Skeletal/drug effects
- Muscle Fibers, Skeletal/metabolism
- Muscle Fibers, Skeletal/pathology
- Muscle, Skeletal/drug effects
- Muscle, Skeletal/metabolism
- Muscle, Skeletal/pathology
- Muscular Dystrophy, Animal/drug therapy
- Muscular Dystrophy, Animal/metabolism
- Muscular Dystrophy, Animal/pathology
- Muscular Dystrophy, Duchenne/drug therapy
- Muscular Dystrophy, Duchenne/metabolism
- Muscular Dystrophy, Duchenne/pathology
- Sarcolemma/drug effects
- Sarcolemma/genetics
- Sarcolemma/metabolism
- Treatment Outcome
- Water-Electrolyte Balance/drug effects
- Water-Electrolyte Balance/genetics
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Affiliation(s)
- Maria Julia Marques
- Departamento de Anatomia, Instituto de Biologia, Universidade Estadual de Campinas, Campinas, São Paulo 13083-970, Brazil.
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Kinali M, Manzur AY, Muntoni F. Recent developments in the management of Duchenne muscular dystrophy. ACTA ACUST UNITED AC 2008. [DOI: 10.1016/j.paed.2007.10.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/16/2023]
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Abstract
PURPOSE OF REVIEW The search for a cure for Duchenne muscular dystrophy and other muscular dystrophies is progressing rapidly despite significant challenges posed by some genes and the complexity of targeting all skeletal muscles. This review focuses on three areas in which experimental clinical studies are in progress. RECENT FINDINGS Two Phase I/IIa gene-therapy trials using adeno-associated viral vectors have recently started, one in limb-girdle muscular dystrophy and one in Duchenne muscular dystrophy. They will assess the safety of the intramuscular administration of the relevant adeno-associated viral vectors, and local efficacy. Two more Phase I/IIa studies are underway in Duchenne muscular dystrophy, focused on the intramuscular administration of antisense oligonucleotides to induce exon skipping. A third study is evaluating efficacy and tolerability of a drug which induces read-through of stop codons in Duchenne muscular dystrophy patients carrying nonsense mutations. SUMMARY These studies should provide proof of principle of these experimental approaches in humans. It is likely that further refinement will be required before extending their use to the wider community of patients with muscular dystrophy. In the meantime it is important to prepare accurate registries of molecularly characterized patients to facilitate their recruitment in future studies.
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Affiliation(s)
- Francesco Muntoni
- Dubowitz Neuromuscular Centre, Department of Paediatrics, Hammersmith Hospital Campus, Imperial College London, London, UK.
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Ratanamart J, Huggins CG, Kirby JA, Shaw JAM. In vitro and in vivo evaluation of intrinsic immunogenicity of reporter and insulin gene therapy plasmids. J Gene Med 2007; 9:703-14. [PMID: 17595049 DOI: 10.1002/jgm.1066] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
BACKGROUND Plasmid DNA vectors offer the potential of safe gene therapy avoiding viral vector-mediated toxicity and immunogenicity. As plasmid DNA is bacterial in origin, presence of bacterial lipopolysaccharide (LPS) or unmethylated CpG dinucleotides may stimulate host innate immunity. METHODS Primary cultures of mouse and rat dendritic cells were established and incubated with bacterial lipopolysaccharide; immunostimulatory CpG oligodeoxynucleotide; control GpC oligodeoxynucleotide; and a range of (pVR1012) plasmids encoding transgenes with increasing CpG content (wild-type and mutant human preproinsulin; non-mammalian eukaryotic eGFP reporter gene; and bacterial beta-galactosidase reporter gene). IL-12 secretion was assayed to determine in vitro plasmid immunogenicity. Local inflammatory response following intramuscular injection of these plasmids, with or without a non-ionic carrier SP1017, was characterised in vivo. RESULTS Dose-responsive LPS and CpG stimulation of IL-12 secretion from dendritic cells was demonstrated. All plasmids induced significant IL-12 secretion in comparison to control unstimulated cells. The beta-galactosidase plasmid had highest CpG content and induced significantly higher IL-12 secretion than constructs containing a eukaryotic transgene. Injection of rat muscle with the beta-galactosidase construct induced greater inflammatory response than human preproinsulin constructs. This was further enhanced by SP1017. At 2 days post-injection, monocyte/macrophage injection site infiltration predominated with CD8-positive lymphocytes predominating at 7 days. There was no evidence of transgene expression in infiltrating immune cells. CONCLUSIONS Dendritic cell immunostimulation may be employed as an in vitro bioassay of innate immune response to plasmid DNA vectors during evaluation for clinical gene therapy.
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Affiliation(s)
- Jarupa Ratanamart
- Diabetes Research Group, Institute of Cell and Molecular Biosciences, University of Newcastle upon Tyne, Framlington Place, Newcastle upon Tyne NE2 4HH, UK
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Yokota T, Pistilli E, Duddy W, Nagaraju K. Potential of oligonucleotide-mediated exon-skipping therapy for Duchenne muscular dystrophy. Expert Opin Biol Ther 2007; 7:831-42. [PMID: 17555369 DOI: 10.1517/14712598.7.6.831] [Citation(s) in RCA: 43] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Abstract
Many of the mutations associated with Duchenne muscular dystrophy can potentially be rescued by exon-skipping therapy, targeting selected exons of prespliced mRNA for the dystrophin gene with antisense oligonucleotides, thereby restoring reading frames. The recent development of antisense oligonucleotides with higher stability and lower toxicity, such as morpholinos, has made it possible to restore dystrophin efficiently in dystrophic mice in vivo with no obvious side effects. There seems little doubt that such exon-skipping therapy is destined to proceed to the clinical application stage in patients with Duchenne muscular dystrophy. One of the remaining issues to be addressed is the skipping of multiple exons because such multi-exon skipping therapy could expand the potential patient target population to include 80% of those with duplication mutations and 90% of those with deletion mutations. At present, this multi-exon skipping strategy is being investigated in dystrophic dogs as well as dystrophic mice. There are several challenges that still need to be overcome, including the low uptake of antisense oligonucleotides into the heart and the need to design efficient, nontoxic, cost-effective oligonucleotides. This review summarizes recent progress in exon-skipping therapy and discusses future perspectives with regard to human clinical trials.
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Affiliation(s)
- Toshifumi Yokota
- Children's National Medical Center, Research Center for Genetic Medicine, Washington, DC 20010, USA.
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