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Biomolecules May 2024Chimerism-based strategies represent a pioneering concept which has led to groundbreaking advancements in regenerative medicine and transplantation. This new approach... (Review)
Review
Chimerism-based strategies represent a pioneering concept which has led to groundbreaking advancements in regenerative medicine and transplantation. This new approach offers therapeutic potential for the treatment of various diseases, including inherited disorders. The ongoing studies on chimeric cells prompted the development of Dystrophin-Expressing Chimeric (DEC) cells which were introduced as a potential therapy for Duchenne Muscular Dystrophy (DMD). DMD is a genetic condition that leads to premature death in adolescent boys and remains incurable with current methods. DEC therapy, created via the fusion of human myoblasts derived from normal and DMD-affected donors, has proven to be safe and efficacious when tested in experimental models of DMD after systemic-intraosseous administration. These studies confirmed increased dystrophin expression, which correlated with functional and morphological improvements in DMD-affected muscles, including cardiac, respiratory, and skeletal muscles. Furthermore, the application of DEC therapy in a clinical study confirmed its long-term safety and efficacy in DMD patients. This review summarizes the development of chimeric cell technology tested in preclinical models and clinical studies, highlighting the potential of DEC therapy in muscle regeneration and repair, and introduces chimeric cell-based therapies as a promising, novel approach for muscle regeneration and the treatment of DMD and other neuromuscular disorders.
Topics: Muscular Dystrophy, Duchenne; Humans; Regeneration; Animals; Cell- and Tissue-Based Therapy; Muscle, Skeletal; Dystrophin; Myoblasts
PubMed: 38785982
DOI: 10.3390/biom14050575 -
Respiratory Physiology & Neurobiology Aug 2024Duchenne muscular dystrophy (DMD) is the most common X-linked disease. DMD is caused by a lack of dystrophin, a critical structural protein in striated muscle....
Duchenne muscular dystrophy (DMD) is the most common X-linked disease. DMD is caused by a lack of dystrophin, a critical structural protein in striated muscle. Dystrophin deficiency leads to inflammation, fibrosis, and muscle atrophy. Boys with DMD have progressive muscle weakness within the diaphragm that results in respiratory failure in the 2nd or 3rd decade of life. The most common DMD mouse model - the mdx mouse - is not sufficient for evaluating genetic medicines that specifically target the human DMD (hDMD) gene sequence. Therefore, a novel transgenic mouse carrying the hDMD gene with an exon 52 deletion was created (hDMDΔ52;mdx). We characterized the respiratory function and pathology in this model using whole body plethysmography, histology, and immunohistochemistry. At 6-months-old, hDMDΔ52;mdx mice have reduced maximal respiration, neuromuscular junction pathology, and fibrosis throughout the diaphragm, which worsens at 12-months-old. In conclusion, the hDMDΔ52;mdx exhibits moderate respiratory pathology, and serves as a relevant animal model to study the impact of novel genetic therapies, including gene editing, on respiratory function.
Topics: Animals; Muscular Dystrophy, Duchenne; Disease Models, Animal; Mice, Transgenic; Mice; Humans; Male; Dystrophin; Mice, Inbred mdx; Diaphragm; Respiratory Insufficiency; Neuromuscular Junction; Mice, Inbred C57BL
PubMed: 38782084
DOI: 10.1016/j.resp.2024.104282 -
Journal of Medicinal Chemistry Jun 2024Duchenne muscular dystrophy (DMD) is a fatal muscle-wasting disease caused by the absence of a dystrophin protein. Elevating utrophin, a dystrophin paralogue, offers an...
Duchenne muscular dystrophy (DMD) is a fatal muscle-wasting disease caused by the absence of a dystrophin protein. Elevating utrophin, a dystrophin paralogue, offers an alternative therapeutic strategy for treating DMD, irrespective of the mutation type. Herein, we report the design and synthesis of novel quinazoline and quinoline-based small molecules as potent utrophin modulators screened via high throughput In-Cell ELISA in C2C12 cells. Remarkably, lead molecule SG-02, identified from a library of 70 molecules, upregulates utrophin 2.7-fold at 800 nM in a dose-dependent manner, marking the highest upregulation within the nanomolar range. SG-02's efficacy was further validated through DMD patient-derived cells, demonstrating a significant 2.3-fold utrophin expression. Mechanistically, SG-02 functions as an AhR antagonist, with excellent binding affinity ( = 41.68 nM). SG-02 also enhances myogenesis, as indicated by an increased MyHC expression. ADME evaluation supports SG-02's oral bioavailability. Overall, SG-02 holds promise for addressing the global DMD population.
Topics: Muscular Dystrophy, Duchenne; Utrophin; Quinolines; Humans; Receptors, Aryl Hydrocarbon; Animals; Mice; Quinazolines; Small Molecule Libraries; Drug Discovery; Up-Regulation; Cell Line; Structure-Activity Relationship; Basic Helix-Loop-Helix Transcription Factors
PubMed: 38771158
DOI: 10.1021/acs.jmedchem.4c00398 -
Disease Models & Mechanisms May 2024Absence of dystrophin results in muscular weakness, chronic inflammation and cardiomyopathy in Duchenne muscular dystrophy (DMD). Pharmacological corticosteroids are the...
Absence of dystrophin results in muscular weakness, chronic inflammation and cardiomyopathy in Duchenne muscular dystrophy (DMD). Pharmacological corticosteroids are the DMD standard of care; however, they have harsh side effects and unclear molecular benefits. It is uncertain whether signaling by physiological corticosteroids and their receptors plays a modifying role in the natural etiology of DMD. Here, we knocked out the glucocorticoid receptor (GR, encoded by Nr3c1) specifically in myofibers and cardiomyocytes within wild-type and mdx52 mice to dissect its role in muscular dystrophy. Double-knockout mice showed significantly worse phenotypes than mdx52 littermate controls in measures of grip strength, hang time, inflammatory pathology and gene expression. In the heart, GR deletion acted additively with dystrophin loss to exacerbate cardiomyopathy, resulting in enlarged hearts, pathological gene expression and systolic dysfunction, consistent with imbalanced mineralocorticoid signaling. The results show that physiological GR functions provide a protective role during muscular dystrophy, directly contrasting its degenerative role in other disease states. These data provide new insights into corticosteroids in disease pathophysiology and establish a new model to investigate cell-autonomous roles of nuclear receptors and mechanisms of pharmacological corticosteroids.
Topics: Animals; Receptors, Glucocorticoid; Mice, Inbred mdx; Mice, Knockout; Dystrophin; Myocardium; Muscular Dystrophy, Duchenne; Muscle, Skeletal; Myocytes, Cardiac; Mice; Cardiomyopathies; Mice, Inbred C57BL; Muscular Dystrophy, Animal; Phenotype; Systole
PubMed: 38770680
DOI: 10.1242/dmm.050397 -
BMC Musculoskeletal Disorders May 2024Duchenne muscular dystrophy (DMD) is a devastating X-linked neuromuscular disorder caused by various defects in the dystrophin gene and still no universal therapy. This...
OBJECTIVE
Duchenne muscular dystrophy (DMD) is a devastating X-linked neuromuscular disorder caused by various defects in the dystrophin gene and still no universal therapy. This study aims to identify the hub genes unrelated to excessive immune response but responsible for DMD progression and explore therapeutic siRNAs, thereby providing a novel treatment.
METHODS
Top ten hub genes for DMD were identified from GSE38417 dataset by using GEO2R and PPI networks based on Cytoscape analysis. The hub genes unrelated to excessive immune response were identified by GeneCards, and their expression was further verified in mdx and C57 mice at 2 and 4 months (M) by (RT-q) PCR and western blotting. Therapeutic siRNAs were deemed as those that could normalize the expression of the validated hub genes in transfected C2C12 cells.
RESULTS
855 up-regulated and 324 down-regulated DEGs were screened from GSE38417 dataset. Five of the top 10 hub genes were considered as the candidate genes unrelated to excessive immune response, and three of these candidates were consistently and significantly up-regulated in mdx mice at 2 M and 4 M when compared with age-matched C57 mice, including Col1a2, Fbn1 and Fn1. Furthermore, the three validated up-regulated candidate genes can be significantly down-regulated by three rational designed siRNA (p < 0.0001), respectively.
CONCLUSION
COL1A2, FBN1 and FN1 may be novel biomarkers for DMD, and the siRNAs designed in our study were help to develop adjunctive therapy for Duchenne muscular dystrophy.
Topics: Muscular Dystrophy, Duchenne; Animals; Mice, Inbred mdx; RNA, Small Interfering; Mice; Mice, Inbred C57BL; Disease Models, Animal; Male; Humans; Protein Interaction Maps
PubMed: 38762732
DOI: 10.1186/s12891-024-07206-6 -
The American Journal of Pathology May 2024Duchenne muscular dystrophy (DMD), caused by loss-of-function mutations in the dystrophin gene, results in progressive muscle weakness and early fatality. Impaired...
Leucyl-tRNA Synthetase Contributes to Muscle Weakness through Mammalian Target of Rapamycin Complex 1 Activation and Autophagy Suppression in a Mouse Model of Duchenne Muscular Dystrophy.
Duchenne muscular dystrophy (DMD), caused by loss-of-function mutations in the dystrophin gene, results in progressive muscle weakness and early fatality. Impaired autophagy is one of the cellular hallmarks of DMD, contributing to the disease progression. Molecular mechanisms underlying the inhibition of autophagy in DMD are not well understood. In the current study, the DMD mouse model mdx is used for the investigation of signaling pathways leading to suppression of autophagy. Mammalian target of rapamycin complex 1 (mTORC1) is found to be hyperactive in the DMD muscles, accompanying muscle weakness and autophagy impairment. Surprisingly, Akt, a well-known upstream regulator of mTORC1, is not responsible for mTORC1 activation or the dystrophic muscle phenotypes. Instead, leucyl-tRNA synthetase (LeuRS) is found to be overexpressed in mdx muscles compared with the wild type. LeuRS is known to activate mTORC1 in a noncanonical mechanism that involves interaction with RagD, an activator of mTORC1. Disrupting LeuRS interaction with RagD by the small-molecule inhibitor BC-LI-0186 reduces mTORC1 activity, restores autophagy, and ameliorates myofiber damage in the mdx muscles. Furthermore, inhibition of LeuRS by BC-LI-0186 improves dystrophic muscle strength in an autophagy-dependent manner. Taken together, our findings uncover a noncanonical function of the housekeeping protein LeuRS as a potential therapeutic target in the treatment of DMD.
PubMed: 38762116
DOI: 10.1016/j.ajpath.2024.04.006 -
Trends in Molecular Medicine May 2024Duchenne muscular dystrophy (DMD) is caused by mutations in the X-linked DMD gene, resulting in the absence of dystrophin, progressive muscle degeneration, and heart... (Review)
Review
Duchenne muscular dystrophy (DMD) is caused by mutations in the X-linked DMD gene, resulting in the absence of dystrophin, progressive muscle degeneration, and heart failure. Genetically tailored pig models resembling human DMD mutations recapitulate the biochemical, clinical, and pathological hallmarks of DMD with an accelerated disease progression compared to human patients. DMD pigs have been used to evaluate therapeutic concepts such as gene editing to reframe a disrupted DMD reading frame or the delivery of artificial chromosome vectors carrying the complete DMD gene. Moreover, DMD pigs have been instrumental in validating new diagnostic modalities such as multispectral optoacoustic tomography (MSOT) for non-invasive monitoring of disease progression. DMD pigs may thus help to bridge the gap between proof-of-concept studies in cellular or rodent models and clinical studies in patients.
PubMed: 38749865
DOI: 10.1016/j.molmed.2024.04.013 -
Innere Medizin (Heidelberg, Germany) Jun 2024Duchenne muscular dystrophy (DMD) is a severe monogenic hereditary disease with early manifestation and a progressive course. Treatment options have so far been... (Review)
Review
BACKGROUND
Duchenne muscular dystrophy (DMD) is a severe monogenic hereditary disease with early manifestation and a progressive course. Treatment options have so far been limited. Gene therapy opens up new options for DMD patients.
OBJECTIVES
Against the background of a further death following DMD gene therapy, the side effects and risks of the gene therapeutics already approved or undergoing clinical trials will be evaluated and alternative gene therapeutics will be described. Based thereon, the future of DMD gene therapy will be discussed.
CURRENT DATA
For the first time, in June 2023, delandistrogene moxeparvovec (SRP-9001), a gene replacement therapy based on an adeno-associated virus (AAV) vector, was approved in the USA for children aged 4-5 years with DMD. Other promising gene therapies are in preclinical development or clinical trials, including CRISPR/Cas9-mediated strategies to restore dystrophin expression. Two deaths following DMD gene therapy with high-dose AAV vectors were attributed to AAV-mediated immune responses. The pre-existing disease underlying the therapy is most likely involved in the fatal AAV toxicity.
CONCLUSIONS
Although gene therapy applications of AAV vectors are generally considered safe, the systemic administration of high vector doses can lead to severe side effects with a potentially fatal outcome in individual patients, especially after activation of the immune system. In the future, new methods for immunosuppression, reduction of AAV dose and alternative vectors will therefore increasingly come to the fore.
Topics: Muscular Dystrophy, Duchenne; Humans; Genetic Therapy; Dependovirus; Genetic Vectors; Child, Preschool; Child; Male
PubMed: 38748280
DOI: 10.1007/s00108-024-01711-5 -
Research Square May 2024Current gene therapy for Duchenne muscular dystrophy (DMD) utilizes adeno-associated virus (AAV) to deliver miniaturized dystrophin (micro-dystrophin or µDys), which...
Current gene therapy for Duchenne muscular dystrophy (DMD) utilizes adeno-associated virus (AAV) to deliver miniaturized dystrophin (micro-dystrophin or µDys), which does not provide full protection for striated muscles as it lacks many important functional domains within full-length (FL) dystrophin. Here we develop a triple vector system to deliver FL-dystrophin into skeletal and cardiac muscles. We rationally split FL-dystrophin into three fragments (N, M, and C) linked to two orthogonal pairs of split intein, allowing efficient, unidirectional assembly of FL-dystrophin. The three fragments packaged in myotropic AAV (MyoAAV4A) restore FL-dystrophin expression in both skeletal and cardiac muscles in male mice. Dystrophin-glycoprotein complex components are also restored in the sarcolemma of dystrophic muscles. MyoAAV4A-delivered FL-dystrophin significantly improves muscle histopathology, contractility, and overall strength comparable to µDys, but unlike µDys, it also restores defective ERK signaling in heart. The FL-dystrophin gene therapy therefore promises to offer superior protection for DMD.
PubMed: 38746161
DOI: 10.21203/rs.3.rs-3867299/v1 -
Frontiers in Physiology 2024Duchenne muscular dystrophy (DMD) is a fatal striated muscle degenerative disease. DMD is caused by loss of dystrophin protein, which results in sarcolemmal instability...
Duchenne muscular dystrophy (DMD) is a fatal striated muscle degenerative disease. DMD is caused by loss of dystrophin protein, which results in sarcolemmal instability and cycles of myofiber degeneration and regeneration. Pathology is exacerbated by overactivation of infiltrating immune cells and fibroblasts, which leads to chronic inflammation and fibrosis. Mineralocorticoid receptors (MR), a type of nuclear steroid hormone receptors, are potential therapeutic targets for DMD. MR antagonists show clinical efficacy on DMD cardiomyopathy and preclinical efficacy on skeletal muscle in DMD models. We have previously generated myofiber and myeloid MR knockout mouse models to dissect cell-specific functions of MR within dystrophic muscles. Here, we compared skeletal muscle gene expression from both knockouts to further define cell-type specific signaling downstream from MR. Myeloid MR knockout increased proinflammatory and profibrotic signaling, including numerous myofibroblast signature genes. was the most highly upregulated fibrotic gene in myeloid MR-knockout skeletal muscle and is a component of fibrosis in dystrophic skeletal muscle. Surprisingly, (), canonically a collagen crosslinker, was increased in both MR knockouts, but did not localize to fibrotic regions of skeletal muscle. Lox localized within myofibers, including only a region of quadriceps muscles. (), another Lox family member, was increased only in myeloid MR knockout muscle and localized specifically to fibrotic regions. This study suggests that MR signaling in the dystrophic muscle microenvironment involves communication between contributing cell types and modulates inflammatory and fibrotic pathways in muscle disease.
PubMed: 38737833
DOI: 10.3389/fphys.2024.1322729