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Skeletal Muscle Nov 2023The lack of functional dystrophin protein in Duchenne muscular dystrophy (DMD) causes chronic skeletal muscle inflammation and degeneration. Therefore, the restoration...
BACKGROUND
The lack of functional dystrophin protein in Duchenne muscular dystrophy (DMD) causes chronic skeletal muscle inflammation and degeneration. Therefore, the restoration of functional dystrophin levels is a fundamental approach for DMD therapy. Electrical impedance myography (EIM) is an emerging tool that provides noninvasive monitoring of muscle conditions and has been suggested as a treatment response biomarker in diverse indications. Although magnetic resonance imaging (MRI) of skeletal muscles has become a standard measurement in clinical trials for DMD, EIM offers distinct advantages, such as portability, user-friendliness, and reduced cost, allowing for remote monitoring of disease progression or response to therapy. To investigate the potential of EIM as a biomarker for DMD, we compared longitudinal EIM data with MRI/histopathological data from an X-linked muscular dystrophy (mdx) mouse model of DMD. In addition, we investigated whether EIM could detect dystrophin-related changes in muscles using antisense-mediated exon skipping in mdx mice.
METHODS
The MRI data for muscle T2, the magnetic resonance spectroscopy (MRS) data for fat fraction, and three EIM parameters with histopathology were longitudinally obtained from the hindlimb muscles of wild-type (WT) and mdx mice. In the EIM study, a cell-penetrating peptide (Pip9b2) conjugated antisense phosphorodiamidate morpholino oligomer (PPMO), designed to induce exon-skipping and restore functional dystrophin production, was administered intravenously to mdx mice.
RESULTS
MRI imaging in mdx mice showed higher T2 intensity at 6 weeks of age in hindlimb muscles compared to WT mice, which decreased at ≥ 9 weeks of age. In contrast, EIM reactance began to decline at 12 weeks of age, with peak reduction at 18 weeks of age in mdx mice. This decline was associated with myofiber atrophy and connective tissue infiltration in the skeletal muscles. Repeated dosing of PPMO (10 mg/kg, 4 times every 2 weeks) in mdx mice led to an increase in muscular dystrophin protein and reversed the decrease in EIM reactance.
CONCLUSIONS
These findings suggest that muscle T2 MRI is sensitive to the early inflammatory response associated with dystrophin deficiency, whereas EIM provides a valuable biomarker for the noninvasive monitoring of subsequent changes in skeletal muscle composition. Furthermore, EIM reactance has the potential to monitor dystrophin-deficient muscle abnormalities and their recovery in response to antisense-mediated exon skipping.
Topics: Mice; Animals; Dystrophin; Mice, Inbred mdx; Electric Impedance; Mice, Inbred C57BL; Muscular Dystrophy, Duchenne; Muscle, Skeletal; Morpholinos; Myography; Biomarkers
PubMed: 37980539
DOI: 10.1186/s13395-023-00331-1 -
JCI Insight Apr 2024Duchenne muscular dystrophy (DMD) is a progressive muscle-wasting disease associated with cardiomyopathy. DMD cardiomyopathy is characterized by abnormal intracellular...
Duchenne muscular dystrophy (DMD) is a progressive muscle-wasting disease associated with cardiomyopathy. DMD cardiomyopathy is characterized by abnormal intracellular Ca2+ homeostasis and mitochondrial dysfunction. We used dystrophin and utrophin double-knockout (mdx:utrn-/-) mice in a sarcolipin (SLN) heterozygous-knockout (sln+/-) background to examine the effect of SLN reduction on mitochondrial function in the dystrophic myocardium. Germline reduction of SLN expression in mdx:utrn-/- mice improved cardiac sarco/endoplasmic reticulum (SR) Ca2+ cycling, reduced cardiac fibrosis, and improved cardiac function. At the cellular level, reducing SLN expression prevented mitochondrial Ca2+ overload, reduced mitochondrial membrane potential loss, and improved mitochondrial function. Transmission electron microscopy of myocardial tissues and proteomic analysis of mitochondria-associated membranes showed that reducing SLN expression improved mitochondrial structure and SR-mitochondria interactions in dystrophic cardiomyocytes. These findings indicate that SLN upregulation plays a substantial role in the pathogenesis of cardiomyopathy and that reducing SLN expression has clinical implications in the treatment of DMD cardiomyopathy.
Topics: Animals; Male; Mice; Calcium; Cardiomyopathies; Disease Models, Animal; Dystrophin; Mice, Inbred mdx; Mice, Knockout; Mitochondria, Heart; Muscle Proteins; Muscular Dystrophy, Duchenne; Myocardium; Myocytes, Cardiac; Proteolipids; Utrophin
PubMed: 38564291
DOI: 10.1172/jci.insight.170185 -
IScience Jul 2023There is no approved therapy for Becker muscular dystrophy (BMD), a genetic muscle disease caused by in-frame dystrophin deletions. We previously developed the...
There is no approved therapy for Becker muscular dystrophy (BMD), a genetic muscle disease caused by in-frame dystrophin deletions. We previously developed the dissociative corticosteroid vamorolone for treatment of the allelic, dystrophin-null disease Duchenne muscular dystrophy. We hypothesize vamorolone can treat BMD by safely reducing inflammatory signaling in muscle and through a novel mechanism of increasing dystrophin protein via suppression of dystrophin-targeting miRNAs. Here, we test this in the mouse model of BMD. Daily oral treatment with vamorolone or prednisolone improves grip strength and hang time phenotypes. Both drugs reduce myofiber size and decrease the percentage of centrally nucleated fibers. Vamorolone shows improved safety versus prednisolone by avoiding or reducing key side effects to behavior and growth. Intriguingly, vamorolone increases dystrophin protein in both heart and skeletal muscle. These data indicate that vamorolone, nearing approval for Duchenne, shows efficacy in mice and therefore warrants clinical investigation in BMD.
PubMed: 37534133
DOI: 10.1016/j.isci.2023.107161 -
Stem Cell Reviews and Reports Jan 2024Duchenne Muscular Dystrophy (DMD) is an inherited genetic disorder characterized by progressive degeneration of muscle tissue, leading to functional disability and... (Review)
Review
Duchenne Muscular Dystrophy (DMD) is an inherited genetic disorder characterized by progressive degeneration of muscle tissue, leading to functional disability and premature death. Despite extensive research efforts, the discovery of a cure for DMD continues to be elusive, emphasizing the need to investigate novel treatment approaches. Cellular therapies have emerged as prospective approaches to address the underlying pathophysiology of DMD. This review provides an examination of the present situation regarding cell-based therapies, including CD133 + cells, muscle precursor cells, mesoangioblasts, bone marrow-derived mononuclear cells, mesenchymal stem cells, cardiosphere-derived cells, and dystrophin-expressing chimeric cells. A total of 12 studies were found eligible to be included as they were completed cell therapy clinical trials, clinical applications, or case reports with quantitative results. The evaluation encompassed an examination of limitations and potential advancements in this particular area of research, along with an assessment of the safety and effectiveness of cell-based therapies in the context of DMD. In general, the available data indicates that diverse cell therapy approaches may present a new, safe, and efficacious treatment modality for patients diagnosed with DMD. However, further studies are required to comprehensively understand the most advantageous treatment approach and therapeutic capacity.
Topics: Humans; Muscular Dystrophy, Duchenne; Muscle, Skeletal; Mesenchymal Stem Cells; Treatment Outcome; Cell- and Tissue-Based Therapy
PubMed: 37955832
DOI: 10.1007/s12015-023-10653-8 -
Biology Open Sep 2023Robust expression of shortened, functional dystrophin provided impetus to develop adeno-associated virus (AAV)-based constructs for clinical application. Because several...
Robust expression of shortened, functional dystrophin provided impetus to develop adeno-associated virus (AAV)-based constructs for clinical application. Because several cassettes are being tested in clinical trials, this study compared the efficacies of four shortened dystrophin-promoter combinations with implications for outcomes in clinical trials: MHCK7 or MCK promoter with a shortened dystrophin transgene containing the N-terminus and spectrin repeats R1, R2, R3 and R24 (rAAVrh74.MHCK7.micro-dystrophin and rAAVrh74.MCK.micro-dystrophin, respectively); shortened dystrophin construct containing the neuronal nitric oxide (nNOS) binding site (rAAVrh74.MHCK7.DV.mini-dystrophin); and shortened dystrophin containing the C-terminus (rAAVrh74.MHCK7.micro-dystrophin.Cterm). Functional and histological benefit were examined at 4 weeks following intramuscular delivery in mdx mice. rAAVrh74.MHCK7.micro-dystrophin provided the most robust transgene expression and significantly increased specific force output in the tibialis anterior muscle. Muscle environment was normalized (i.e. reductions in central nucleation), indicating functional and histological advantages of rAAVrh74.MHCK7.micro-dystrophin. Thus, promoter choice and transgene design are critical for optimal dystrophin expression/distribution for maximal functional improvement.
Topics: Mice; Animals; Dystrophin; Muscular Dystrophy, Duchenne; Mice, Inbred mdx; Dependovirus; Actin Cytoskeleton; Disease Models, Animal
PubMed: 37670674
DOI: 10.1242/bio.059797 -
Expert Opinion on Investigational Drugs Mar 2024Current therapies are unable to cure Duchenne muscular dystrophy (DMD), a severe and common form of muscular dystrophy, and instead aim to delay disease progression.... (Review)
Review
INTRODUCTION
Current therapies are unable to cure Duchenne muscular dystrophy (DMD), a severe and common form of muscular dystrophy, and instead aim to delay disease progression. Several treatments currently in phase I trials could increase the number of therapeutic options available to patients.
AREAS COVERED
This review aims to provide an overview of current treatments undergoing or having recently undergone early-stage trials. Several exon-skipping and gene therapy approaches are currently being investigated at the clinical stage to address an unmet need for DMD treatments. This article also covers Phase I trials from the last 5 years that involve inhibitors, small molecules, a purified synthetic flavanol, a cell-based therapy, and repurposed cardiac or tumor medications.
EXPERT OPINION
With antisense oligonucleotide (AON) treatments making up the majority of conditionally approved DMD therapies, most of the clinical trials occurring within the last 5 years have also evaluated exon-skipping AONs. The approval of Elevidys, a micro-dystrophin therapy, is reflected in a recent trend toward gene transfer therapies in phase I DMD clinical trials, but their safety and efficacy are being established in this phase of development. Other Phase I clinical-stage approaches are diverse, but have a range in efficacy, safety, and endpoint measures.
Topics: Humans; Genetic Therapy; Muscular Dystrophy, Duchenne; Oligonucleotides, Antisense; RNA Splicing; Clinical Trials as Topic
PubMed: 38291016
DOI: 10.1080/13543784.2024.2313105 -
Plasmid Jul 2023Duchenne Muscular Dystrophy and Cystic Fibrosis are two major monogenetic diseases which could be treated by non-viral gene therapy. For this purpose, plasmid DNA (pDNA)...
Duchenne Muscular Dystrophy and Cystic Fibrosis are two major monogenetic diseases which could be treated by non-viral gene therapy. For this purpose, plasmid DNA (pDNA) coding for the functional genes requires its equipment with signal molecules favouring its intracellular trafficking and delivery in the nucleus of the target cells. Here, two novel constructions of large pDNAs encoding the Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) and full-length dystrophin (DYS) genes are reported. The expression of CFTR and DYS genes are driven respectively by the hCEF1 airway epithelial cells and spc5-12 muscle cells specific promoter. Those pDNAs encode also the luciferase reporter gene driven by the CMV promoter to evaluate gene delivery in animals by bioluminescence. In addition, oligopurine • oligopyrimidine sequences are inserted to enable equipment of pDNAs with peptides conjugated with a triple helix forming oligonucleotide (TFO). Furthermore, specific κB sequences are also inserted to promote their NFκB-mediated nuclear import. pDNA constructions are reported; transfection efficiency, tissue specific expression of CFTR and dystrophin in target cells, and triple helix formation are demonstrated. These plasmids are tools of interest to develop non-viral gene therapy of Cystic Fibrosis and Duchenne Muscular Dystrophy.
Topics: Animals; Active Transport, Cell Nucleus; Cystic Fibrosis; Cystic Fibrosis Transmembrane Conductance Regulator; DNA; Dystrophin; Genes, Reporter; Muscular Dystrophy, Duchenne; Plasmids
PubMed: 37207938
DOI: 10.1016/j.plasmid.2023.102686 -
Current Gene Therapy 2024
Topics: Humans; Muscular Dystrophy, Duchenne; Genetic Therapy; Dystrophin; Genetic Vectors
PubMed: 36959131
DOI: 10.2174/1566523223666230320120839 -
Annals of Clinical and Translational... Dec 2023Becker muscular dystrophy (BMD) is a milder variant of Duchenne muscular dystrophy (DMD), a lethal X-linked muscular disorder. Here, we aim to investigat the clinical...
OBJECTIVE
Becker muscular dystrophy (BMD) is a milder variant of Duchenne muscular dystrophy (DMD), a lethal X-linked muscular disorder. Here, we aim to investigat the clinical involvement of skeletal, respiratory, cardiac, and central nervous systems in patients with BMD, as well as genotype-phenotype relationships.
METHODS
This nationwide cohort study investigated the clinical manifestations and genotype-phenotype relationships in 225 patients with BMD having in-frame deletion from 22 medical centers. The primary outcome was to elucidate the association of genotype with skeletal muscle, respiratory, cardiac, and central nervous system disorders. Descriptive statistics were used to analyze the data.
RESULTS
The average age of the subjects was 31.5 (range, 1-81) years. Initial symptoms of BMD were muscular (60%), followed by asymptomatic hypercreatine kinasemia (32.4%) and central nervous system disorders (5.3%). Gait disturbance was observed in 53.8% of patients and the average age at wheelchair introduction was 36.5 years. The ventilator introduction rate was 6.7% at an average age of 36.6 years. More than 30% of patients had an abnormal electrocardiogram and approximately 15% had heart failure symptoms. Cardiac function on echocardiography varied significantly among the patients. The frequencies of seizures and intellectual/developmental disability were 8.0% and 16.9%, respectively. Exon 45-47deletion (del) was the most common (22.6%), followed by exon 45-48del (13.1%). Patients with exon 45-49del patients demonstrated severe skeletal muscle damage. Patients with exon 45-47del and exon 45-55del patients did not require ventilator use.
INTERPRETATION
The study provides important prognostic information for patients and clinicians to establish therapy plans and to implement preventative medicine.
Topics: Humans; Infant; Child, Preschool; Child; Adolescent; Young Adult; Adult; Middle Aged; Aged; Aged, 80 and over; Muscular Dystrophy, Duchenne; Dystrophin; Cohort Studies; Genotype; Intellectual Disability; Heart Diseases; Central Nervous System Diseases
PubMed: 37882106
DOI: 10.1002/acn3.51925 -
Cell Death & Disease Sep 2023Duchenne muscular dystrophy is a genetic disease produced by mutations in the dystrophin gene characterized by early onset muscle weakness leading to severe and...
Duchenne muscular dystrophy is a genetic disease produced by mutations in the dystrophin gene characterized by early onset muscle weakness leading to severe and irreversible disability. The cellular and molecular consequences of the lack of dystrophin in humans are only partially known, which is crucial for the development of new therapies aiming to slow or stop the progression of the disease. Here we have analyzed quadriceps muscle biopsies of seven DMD patients aged 2 to 4 years old and five age and gender matched controls using single nuclei RNA sequencing (snRNAseq) and correlated the results obtained with clinical data. SnRNAseq identified significant differences in the proportion of cell population present in the muscle samples, including an increase in the number of regenerative fibers, satellite cells, and fibro-adipogenic progenitor cells (FAPs) and a decrease in the number of slow fibers and smooth muscle cells. Muscle samples from the younger patients with stable mild weakness were characterized by an increase in regenerative fibers, while older patients with moderate and progressive weakness were characterized by loss of muscle fibers and an increase in FAPs. An analysis of the gene expression profile in muscle fibers identified a strong regenerative signature in DMD samples characterized by the upregulation of genes involved in myogenesis and muscle hypertrophy. In the case of FAPs, we observed upregulation of genes involved in the extracellular matrix regeneration but also several signaling pathways. Indeed, further analysis of the potential intercellular communication profile showed a dysregulation of the communication profile in DMD samples identifying FAPs as a key regulator of cell signaling in DMD muscle samples. In conclusion, our study has identified significant differences at the cellular and molecular levels in the different cell populations present in skeletal muscle samples of patients with DMD compared to controls.
Topics: Humans; Child, Preschool; Muscular Dystrophy, Duchenne; Dystrophin; Transcriptome; Muscle Fibers, Skeletal; Signal Transduction
PubMed: 37673877
DOI: 10.1038/s41419-023-06103-5