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Nature Reviews. Disease Primers Feb 2021Duchenne muscular dystrophy is a severe, progressive, muscle-wasting disease that leads to difficulties with movement and, eventually, to the need for assisted... (Review)
Review
Duchenne muscular dystrophy is a severe, progressive, muscle-wasting disease that leads to difficulties with movement and, eventually, to the need for assisted ventilation and premature death. The disease is caused by mutations in DMD (encoding dystrophin) that abolish the production of dystrophin in muscle. Muscles without dystrophin are more sensitive to damage, resulting in progressive loss of muscle tissue and function, in addition to cardiomyopathy. Recent studies have greatly deepened our understanding of the primary and secondary pathogenetic mechanisms. Guidelines for the multidisciplinary care for Duchenne muscular dystrophy that address obtaining a genetic diagnosis and managing the various aspects of the disease have been established. In addition, a number of therapies that aim to restore the missing dystrophin protein or address secondary pathology have received regulatory approval and many others are in clinical development.
Topics: Animals; Disease Models, Animal; Dystrophin; Humans; Muscular Dystrophy, Duchenne
PubMed: 33602943
DOI: 10.1038/s41572-021-00248-3 -
Molecular Therapy : the Journal of the... Oct 2018Duchenne muscular dystrophy (DMD) is a lethal muscle disease caused by dystrophin gene mutation. Conceptually, replacing the mutated gene with a normal one would cure... (Review)
Review
Duchenne muscular dystrophy (DMD) is a lethal muscle disease caused by dystrophin gene mutation. Conceptually, replacing the mutated gene with a normal one would cure the disease. However, this task has encountered significant challenges due to the enormous size of the gene and the distribution of muscle throughout the body. The former creates a hurdle for viral vector packaging and the latter begs for whole-body therapy. To address these obstacles, investigators have invented the highly abbreviated micro-dystrophin gene and developed body-wide systemic gene transfer with adeno-associated virus (AAV). Numerous microgene configurations and various AAV serotypes have been explored in animal models in many laboratories. Preclinical data suggests that intravascular AAV micro-dystrophin delivery can significantly ameliorate muscle pathology, enhance muscle force, and attenuate dystrophic cardiomyopathy in animals. Against this backdrop, several clinical trials have been initiated to test the safety and tolerability of this promising therapy in DMD patients. While these trials are not powered to reach a conclusion on clinical efficacy, findings will inform the field on the prospects of body-wide DMD therapy with a synthetic micro-dystrophin AAV vector. This review discusses the history, current status, and future directions of systemic AAV micro-dystrophin therapy.
Topics: Dependovirus; Dystrophin; Genetic Therapy; Genetic Vectors; Humans; Muscle, Skeletal; Muscular Dystrophy, Duchenne
PubMed: 30093306
DOI: 10.1016/j.ymthe.2018.07.011 -
Comprehensive Physiology Jul 2015The dystrophin complex stabilizes the plasma membrane of striated muscle cells. Loss of function mutations in the genes encoding dystrophin, or the associated proteins,... (Review)
Review
The dystrophin complex stabilizes the plasma membrane of striated muscle cells. Loss of function mutations in the genes encoding dystrophin, or the associated proteins, trigger instability of the plasma membrane, and myofiber loss. Mutations in dystrophin have been extensively cataloged, providing remarkable structure-function correlation between predicted protein structure and clinical outcomes. These data have highlighted dystrophin regions necessary for in vivo function and fueled the design of viral vectors and now, exon skipping approaches for use in dystrophin restoration therapies. However, dystrophin restoration is likely more complex, owing to the role of the dystrophin complex as a broad cytoskeletal integrator. This review will focus on dystrophin restoration, with emphasis on the regions of dystrophin essential for interacting with its associated proteins and discuss the structural implications of these approaches.
Topics: Animals; Dystrophin; Dystrophin-Associated Proteins; Genetic Therapy; Humans; Muscular Dystrophies
PubMed: 26140716
DOI: 10.1002/cphy.c140048 -
International Journal of Molecular... Feb 2022Duchenne muscular dystrophy (DMD) is an X-linked recessive neuromuscular disorder with a prevalence of approximately 1 in 3500-5000 males. DMD manifests as... (Review)
Review
Duchenne muscular dystrophy (DMD) is an X-linked recessive neuromuscular disorder with a prevalence of approximately 1 in 3500-5000 males. DMD manifests as childhood-onset muscle degeneration, followed by loss of ambulation, cardiomyopathy, and death in early adulthood due to a lack of functional dystrophin protein. Out-of-frame mutations in the dystrophin gene are the most common underlying cause of DMD. Gene editing via the clustered regularly interspaced short palindromic repeats (CRISPR) system is a promising therapeutic for DMD, as it can permanently correct DMD mutations and thus restore the reading frame, allowing for the production of functional dystrophin. The specific mechanism of gene editing can vary based on a variety of factors such as the number of cuts generated by CRISPR, the presence of an exogenous DNA template, or the current cell cycle stage. CRISPR-mediated gene editing for DMD has been tested both in vitro and in vivo, with many of these studies discussed herein. Additionally, novel modifications to the CRISPR system such as base or prime editors allow for more precise gene editing. Despite recent advances, limitations remain including delivery efficiency, off-target mutagenesis, and long-term maintenance of dystrophin. Further studies focusing on safety and accuracy of the CRISPR system are necessary prior to clinical translation.
Topics: Animals; CRISPR-Cas Systems; Disease Models, Animal; Dystrophin; Frameshift Mutation; Gene Editing; Humans; Male; Muscular Dystrophy, Duchenne; Reading Frames; Translational Research, Biomedical
PubMed: 35163754
DOI: 10.3390/ijms23031832 -
Nature Communications Dec 2021Genome editing therapy for Duchenne muscular dystrophy (DMD) holds great promise, however, one major obstacle is delivery of the CRISPR-Cas9/sgRNA system to skeletal...
Genome editing therapy for Duchenne muscular dystrophy (DMD) holds great promise, however, one major obstacle is delivery of the CRISPR-Cas9/sgRNA system to skeletal muscle tissues. In general, AAV vectors are used for in vivo delivery, but AAV injections cannot be repeated because of neutralization antibodies. Here we report a chemically defined lipid nanoparticle (LNP) system which is able to deliver Cas9 mRNA and sgRNA into skeletal muscle by repeated intramuscular injections. Although the expressions of Cas9 protein and sgRNA were transient, our LNP system could induce stable genomic exon skipping and restore dystrophin protein in a DMD mouse model that harbors a humanized exon sequence. Furthermore, administration of our LNP via limb perfusion method enables to target multiple muscle groups. The repeated administration and low immunogenicity of our LNP system are promising features for a delivery vehicle of CRISPR-Cas9 to treat skeletal muscle disorders.
Topics: Animals; CRISPR-Associated Protein 9; CRISPR-Cas Systems; Disease Models, Animal; Dystrophin; Exons; Gene Editing; Genetic Therapy; Humans; Liposomes; Mice; Muscle, Skeletal; Muscular Dystrophy, Duchenne; Nanoparticles; Neuromuscular Diseases; RNA, Messenger
PubMed: 34880218
DOI: 10.1038/s41467-021-26714-w -
Neurology May 2020To report safety, pharmacokinetics, exon 53 skipping, and dystrophin expression in golodirsen-treated patients with Duchenne muscular dystrophy (DMD) amenable to exon 53... (Randomized Controlled Trial)
Randomized Controlled Trial
OBJECTIVE
To report safety, pharmacokinetics, exon 53 skipping, and dystrophin expression in golodirsen-treated patients with Duchenne muscular dystrophy (DMD) amenable to exon 53 skipping.
METHODS
Part 1 was a randomized, double-blind, placebo-controlled, 12-week dose titration of once-weekly golodirsen; part 2 is an ongoing, open-label evaluation. Safety and pharmacokinetics were primary and secondary objectives of part 1. Primary biological outcome measures of part 2 were blinded exon skipping and dystrophin protein production on muscle biopsies (baseline, week 48) evaluated, respectively, using reverse transcription PCR and Western blot and immunohistochemistry.
RESULTS
Twelve patients were randomized to receive golodirsen (n = 8) or placebo (n = 4) in part 1. All from part 1 plus 13 additional patients received 30 mg/kg golodirsen in part 2. Safety findings were consistent with those previously observed in pediatric patients with DMD. Most of the study drug was excreted within 4 hours following administration. A significant increase in exon 53 skipping was associated with ∼16-fold increase over baseline in dystrophin protein expression at week 48, with a mean percent normal dystrophin protein standard of 1.019% (range, 0.09%-4.30%). Sarcolemmal localization of dystrophin was demonstrated by significantly increased dystrophin-positive fibers (week 48, < 0.001) and a positive correlation (Spearman = 0.663; < 0.001) with dystrophin protein change from baseline, measured by Western blot and immunohistochemistry.
CONCLUSION
Golodirsen was well-tolerated; muscle biopsies from golodirsen-treated patients showed increased exon 53 skipping, dystrophin production, and correct dystrophin sarcolemmal localization.
CLINICALTRIALSGOV IDENTIFIER
NCT02310906.
CLASSIFICATION OF EVIDENCE
This study provides Class I evidence that golodirsen is safe and Class IV evidence that it induces exon skipping and novel dystrophin as confirmed by 3 different assays.
Topics: Administration, Intravenous; Adolescent; Child; Dose-Response Relationship, Drug; Double-Blind Method; Dystrophin; Fluorescent Antibody Technique; Humans; Male; Muscle, Skeletal; Muscular Dystrophy, Duchenne; Oligonucleotides; Sequence Deletion
PubMed: 32139505
DOI: 10.1212/WNL.0000000000009233 -
Science (New York, N.Y.) Oct 2018Mutations in the gene encoding dystrophin, a protein that maintains muscle integrity and function, cause Duchenne muscular dystrophy (DMD). The deltaE50-MD dog model of...
Mutations in the gene encoding dystrophin, a protein that maintains muscle integrity and function, cause Duchenne muscular dystrophy (DMD). The deltaE50-MD dog model of DMD harbors a mutation corresponding to a mutational "hotspot" in the human gene. We used adeno-associated viruses to deliver CRISPR gene editing components to four dogs and examined dystrophin protein expression 6 weeks after intramuscular delivery ( = 2) or 8 weeks after systemic delivery ( = 2). After systemic delivery in skeletal muscle, dystrophin was restored to levels ranging from 3 to 90% of normal, depending on muscle type. In cardiac muscle, dystrophin levels in the dog receiving the highest dose reached 92% of normal. The treated dogs also showed improved muscle histology. These large-animal data support the concept that, with further development, gene editing approaches may prove clinically useful for the treatment of DMD.
Topics: Adenoviridae; Animals; CRISPR-Cas Systems; Disease Models, Animal; Dogs; Dystrophin; Female; Gene Editing; Gene Transfer Techniques; Male; Muscular Dystrophy, Duchenne
PubMed: 30166439
DOI: 10.1126/science.aau1549 -
Disease Models & Mechanisms Mar 2015Duchenne muscular dystrophy (DMD) is a progressive muscle-wasting disorder. It is caused by loss-of-function mutations in the dystrophin gene. Currently, there is no... (Review)
Review
Duchenne muscular dystrophy (DMD) is a progressive muscle-wasting disorder. It is caused by loss-of-function mutations in the dystrophin gene. Currently, there is no cure. A highly promising therapeutic strategy is to replace or repair the defective dystrophin gene by gene therapy. Numerous animal models of DMD have been developed over the last 30 years, ranging from invertebrate to large mammalian models. mdx mice are the most commonly employed models in DMD research and have been used to lay the groundwork for DMD gene therapy. After ~30 years of development, the field has reached the stage at which the results in mdx mice can be validated and scaled-up in symptomatic large animals. The canine DMD (cDMD) model will be excellent for these studies. In this article, we review the animal models for DMD, the pros and cons of each model system, and the history and progress of preclinical DMD gene therapy research in the animal models. We also discuss the current and emerging challenges in this field and ways to address these challenges using animal models, in particular cDMD dogs.
Topics: Animals; Cardiomyopathies; Disease Models, Animal; Dystrophin; Genetic Therapy; Muscular Dystrophy, Duchenne; Neurons
PubMed: 25740330
DOI: 10.1242/dmm.018424 -
International Journal of Molecular... Jul 2022Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD), which represent the range of dystrophinopathies, account for nearly 80% of muscle dystrophy. DMD... (Review)
Review
Duchenne muscular dystrophy (DMD) and Becker muscular dystrophy (BMD), which represent the range of dystrophinopathies, account for nearly 80% of muscle dystrophy. DMD and BMD result from the loss of a functional dystrophin protein, and the leading cause of death in these patients is cardiac remodeling and heart failure. The pathogenesis and progression of the more severe form of DMD have been extensively studied and are controlled by many determinants, including microRNAs (miRNAs). The regulatory role of miRNAs in muscle function and the differential miRNA expression in muscular dystrophy indicate the clinical significance of miRNAs. This review discusses the relevant microRNAs as potential biomarkers and therapeutic targets for DMD and DMD cardiomyopathy as examples of dystrophinopathies.
Topics: Biomarkers; Cardiomyopathies; Dystrophin; Heart; Humans; MicroRNAs; Muscular Dystrophy, Duchenne
PubMed: 35887128
DOI: 10.3390/ijms23147785 -
Nature Communications Nov 2022The absence of dystrophin in Duchenne muscular dystrophy disrupts the dystrophin-associated glycoprotein complex resulting in skeletal muscle fiber fragility and...
The absence of dystrophin in Duchenne muscular dystrophy disrupts the dystrophin-associated glycoprotein complex resulting in skeletal muscle fiber fragility and atrophy, associated with fibrosis as well as microtubule and neuromuscular junction disorganization. The specific, non-conventional cytoplasmic histone deacetylase 6 (HDAC6) was recently shown to regulate acetylcholine receptor distribution and muscle atrophy. Here, we report that administration of the HDAC6 selective inhibitor tubastatin A to the Duchenne muscular dystrophy, mdx mouse model increases muscle strength, improves microtubule, neuromuscular junction, and dystrophin-associated glycoprotein complex organization, and reduces muscle atrophy and fibrosis. Interestingly, we found that the beneficial effects of HDAC6 inhibition involve the downregulation of transforming growth factor beta signaling. By increasing Smad3 acetylation in the cytoplasm, HDAC6 inhibition reduces Smad2/3 phosphorylation, nuclear translocation, and transcriptional activity. These findings provide in vivo evidence that Smad3 is a new target of HDAC6 and implicate HDAC6 as a potential therapeutic target in Duchenne muscular dystrophy.
Topics: Mice; Animals; Dystrophin; Mice, Inbred mdx; Histone Deacetylase 6; Muscular Dystrophy, Duchenne; Acetylation; Transforming Growth Factor beta; Muscle, Skeletal; Histone Deacetylase Inhibitors; Fibrosis; Phenotype; Muscular Atrophy; Glycoproteins
PubMed: 36402791
DOI: 10.1038/s41467-022-34831-3