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Molecular Therapy. Nucleic Acids Jun 2024Duchenne muscular dystrophy (DMD) is the most prevalent herediatry disease in men, characterized by dystrophin deficiency, progressive muscle wasting, cardiac...
Duchenne muscular dystrophy (DMD) is the most prevalent herediatry disease in men, characterized by dystrophin deficiency, progressive muscle wasting, cardiac insufficiency, and premature mortality, with no effective therapeutic options. Here, we investigated whether adenine base editing can correct pathological nonsense point mutations leading to premature stop codons in the dystrophin gene. We identified 27 causative nonsense mutations in our DMD patient cohort. Treatment with adenine base editor (ABE) could restore dystrophin expression by direct A-to-G editing of pathological nonsense mutations in cardiomyocytes generated from DMD patient-derived induced pluripotent stem cells. We also generated two humanized mouse models of DMD expressing mutation-bearing exons 23 or 30 of human dystrophin gene. Intramuscular administration of ABE, driven by ubiquitous or muscle-specific promoters could correct these nonsense mutations , albeit with higher efficiency in exon 30, restoring dystrophin expression in skeletal fibers of humanized DMD mice. Moreover, a single systemic delivery of ABE with human single guide RNA (sgRNA) could induce body-wide dystrophin expression and improve muscle function in rotarod tests of humanized DMD mice. These findings demonstrate that ABE with human sgRNAs can confer therapeutic alleviation of DMD in mice, providing a basis for development of adenine base editing therapies in monogenic diseases.
PubMed: 38571746
DOI: 10.1016/j.omtn.2024.102165 -
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 -
Cureus Feb 2024Dilated cardiomyopathy (DCM) is an underrecognized condition with a myriad of etiologies, but it is often labeled idiopathic. However, genetic mutations are emerging as...
Dilated cardiomyopathy (DCM) is an underrecognized condition with a myriad of etiologies, but it is often labeled idiopathic. However, genetic mutations are emerging as a more common cause of idiopathic DCM than previously believed. Herein, we present a case of a previously healthy 45-year-old woman who presented with three weeks of exertional dyspnea and orthopnea. An echocardiogram showed DCM with severely reduced systolic function and diastolic dysfunction. She was extensively worked up for potential etiologies of her heart failure which included HIV testing, parasite smear, viral serologies, autoimmune testing, cardiac MRI for infiltrative diseases, and coronary catheterization. She was ultimately tested for genetic mutations which revealed a 49-51 exon deletion of the dystrophin (Duchenne muscular dystrophy (DMD)) gene. This case highlights the guideline-based evaluation and management of new-onset heart failure in a healthy 45-year-old female without known predisposing risk factors or family history. It also sheds light on the expansive genetic etiologies that have only recently been identified in those with idiopathic cardiomyopathy. Further research is crucial to improve our understanding of genetic associations of cardiomyopathy.
PubMed: 38562263
DOI: 10.7759/cureus.55170 -
International Heart Journal 2024Duchenne muscular dystrophy (DMD) is an intractable X-linked myopathy caused by dystrophin gene mutations. Patients with DMD suffer from progressive muscle weakness,...
Duchenne muscular dystrophy (DMD) is an intractable X-linked myopathy caused by dystrophin gene mutations. Patients with DMD suffer from progressive muscle weakness, inevitable cardiomyopathy, increased heart rate (HR), and decreased blood pressure (BP). The aim of this study was to clarify the efficacy and tolerability of ivabradine treatment for DMD cardiomyopathy.A retrospective analysis was performed in 11 patients with DMD, who received ivabradine treatment for more than 1 year. Clinical results were analyzed before (baseline), 6 months after, and 12 months after the ivabradine administration.The initial ivabradine dose was 2.0 ± 1.2 mg/day and the final dose was 5.6 ± 4.0 mg/day. The baseline BP was 95/64 mmHg. A non-significant BP decrease to 90/57 mmHg was observed at 1 month but it recovered to 97/62 mmHg at 12 months after ivabradine administration. The baseline HR was 93 ± 6 bpm and it decreased to 74 ± 12 bpm at 6 months (P = 0.011), and to 77 ± 10 bpm at 12 months (P = 0.008). A linear correlation (y = 2.2x + 5.1) was also observed between the ivabradine dose (x mg/day) and HR decrease (y bpm). The baseline LVEF was 38 ± 12% and it significantly increased to 42 ± 9% at 6 months (P = 0.011) and to 41 ± 11% at 12 months (P = 0.038). Only 1 patient with the lowest BMI of 11.0 kg/m and BP of 79/58 mmHg discontinued ivabradine treatment at 6 months, while 1-year administration was well-tolerated in the other 10 patients.Ivabradine decreased HR and increased LVEF without lowering BP, suggesting it can be a treatment option for DMD cardiomyopathy.
Topics: Humans; Ivabradine; Muscular Dystrophy, Duchenne; Retrospective Studies; Cardiomyopathies; Dystrophin
PubMed: 38556332
DOI: 10.1536/ihj.23-563 -
Heliyon Mar 2024Most pathogenic variants are detectable and interpretable by standard genetic testing for dystrophinopthies. However, approximately 1∼3% of dystrophinopthies patients...
Most pathogenic variants are detectable and interpretable by standard genetic testing for dystrophinopthies. However, approximately 1∼3% of dystrophinopthies patients still do not have a detectable variant after standard genetic testing, most likely due to structural chromosome rearrangements and/or deep intronic pseudoexon-activating variants. Here, we report on a boy with a suspected diagnosis of Becker muscular dystrophy (BMD) who remained without a detectable variant after exonic DNA-based standard genetic testing. mRNA studies and genomic Sanger sequencing were performed in the boy, followed by splicing analyses. We successfully detected a novel deep intronic disease-causing variant in the gene (c.2380 + 3317A > T), which consequently resulting in a new pseudoexon activation through the enhancement of a cryptic donor splice site. The patient was therefore genetically diagnosed with BMD. Our case report further emphasizes the significant role of disease-causing splicing variants within deep intronic regions in genetically undiagnosed dystrophinopathies.
PubMed: 38545205
DOI: 10.1016/j.heliyon.2024.e28020 -
Biomolecules Mar 2024Duchenne muscular dystrophy is caused by loss of the dystrophin protein. This pathology is accompanied by mitochondrial dysfunction contributing to muscle fiber...
Duchenne muscular dystrophy is caused by loss of the dystrophin protein. This pathology is accompanied by mitochondrial dysfunction contributing to muscle fiber instability. It is known that mitochondria-targeted in vivo therapy mitigates pathology and improves the quality of life of model animals. In the present work, we applied mitochondrial transplantation therapy (MTT) to correct the pathology in dystrophin-deficient mice. Intramuscular injections of allogeneic mitochondria obtained from healthy animals into the hind limbs of mice alleviated skeletal muscle injury, reduced calcium deposits in muscles and serum creatine kinase levels, and improved the grip strength of the hind limbs and motor activity of recipient mice. We noted normalization of the mitochondrial ultrastructure and sarcoplasmic reticulum/mitochondria interactions in muscles. At the same time, we revealed a decrease in the efficiency of oxidative phosphorylation in the skeletal muscle mitochondria of recipient mice accompanied by a reduction in lipid peroxidation products (MDA products) and reduced calcium overloading. We found no effect of MTT on the expression of mitochondrial signature genes (, , , , ) and on the level of mtDNA. Our results show that systemic MTT mitigates the development of destructive processes in the quadriceps muscle of mice.
Topics: Animals; Mice; Mice, Inbred mdx; Dystrophin; Calcium; Quality of Life; Muscular Dystrophy, Duchenne; Muscle, Skeletal; Mitochondria
PubMed: 38540736
DOI: 10.3390/biom14030316 -
Biomedicines Mar 2024Duchenne Muscular Dystrophy (DMD) is a lethal disease caused by mutation in the dystrophin gene. Currently there is no cure for DMD. We introduced a novel human...
Amelioration of Morphological Pathology in Cardiac, Respiratory, and Skeletal Muscles Following Intraosseous Administration of Human Dystrophin Expressing Chimeric (DEC) Cells in Duchenne Muscular Dystrophy Model.
Duchenne Muscular Dystrophy (DMD) is a lethal disease caused by mutation in the dystrophin gene. Currently there is no cure for DMD. We introduced a novel human Dystrophin Expressing Chimeric (DEC) cell therapy of myoblast origin and confirmed the safety and efficacy of DEC in the mouse models of DMD. In this study, we assessed histological and morphological changes in the cardiac, diaphragm, and gastrocnemius muscles of the / mice after the transplantation of human DEC therapy via the systemic-intraosseous route. The efficacy of different DEC doses was evaluated at 90 days (0.5 × 10 and 1 × 10 DEC cells) and 180 days (1 × 10 and 5 × 10 DEC cells) after administration. The evaluation of Hematoxylin & Eosin (H&E)-stained sectional slices of cardiac, diaphragm, and gastrocnemius muscles included assessment of muscle fiber size by minimal Feret's diameter method using ImageJ software. The overall improvement in muscle morphology was observed in DMD-affected target muscles in both studies, as evidenced by a shift in fiber size distribution toward the wild type (WT) phenotype and by an increase in the mean Feret's diameter compared to the vehicle-injected controls. These findings confirm the long-term efficacy of human DEC therapy in the improvement of overall morphological pathology in the muscles affected by DMD and introduce DEC as a novel therapeutic approach for DMD patients.
PubMed: 38540201
DOI: 10.3390/biomedicines12030586 -
CPT: Pharmacometrics & Systems... May 2024Duchenne muscular dystrophy (DMD) is a rare X-linked recessive disorder characterized by loss-of-function mutations in the gene encoding dystrophin. These mutations lead...
Duchenne muscular dystrophy (DMD) is a rare X-linked recessive disorder characterized by loss-of-function mutations in the gene encoding dystrophin. These mutations lead to progressive functional deterioration including muscle weakness, respiratory insufficiency, and musculoskeletal deformities. Three-dimensional gait analysis (3DGA) has been used as a tool to analyze gait pathology through the quantification of altered joint kinematics, kinetics, and muscle activity patterns. Among 3DGA indices, the Gait Profile Score (GPS), has been used as a sensitive overall measure to detect clinically relevant changes in gait patterns in children with DMD. To enhance our understanding of the clinical translation of 3DGA, we report here the development of a population nonlinear mixed-effect model that jointly describes the disease progression of the 3DGA index, GPS, and the functional endpoint, North Star Ambulatory Assessment (NSAA). The final model consists of a quadratic structure for GPS progression and a linear structure for GPS-NSAA correlation. Our model was able to capture the improvement in function in GPS and NSAA in younger subjects, as well as the decline of function in older subjects. Furthermore, the model predicted NSAA (CFB) at 1 year reasonably well for DMD subjects ≤7 years old at baseline. The model tended to slightly underpredict the decline in NSAA after 1 year for those >7 years old at baseline, but the prediction summary statistics were well maintained within the standard deviation of observed data. Quantitative models such as this may help answer clinically relevant questions to facilitate the development of novel therapies in DMD.
Topics: Humans; Muscular Dystrophy, Duchenne; Child; Disease Progression; Longitudinal Studies; Child, Preschool; Gait; Male; Adolescent; Gait Analysis
PubMed: 38539027
DOI: 10.1002/psp4.13126 -
Fluids and Barriers of the CNS Mar 2024Waste from the brain has been shown to be cleared via the perivascular spaces through the so-called glymphatic system. According to this model the cerebrospinal fluid...
Waste from the brain has been shown to be cleared via the perivascular spaces through the so-called glymphatic system. According to this model the cerebrospinal fluid (CSF) enters the brain in perivascular spaces of arteries, crosses the astrocyte endfoot layer, flows through the parenchyma collecting waste that is subsequently drained along veins. Glymphatic clearance is dependent on astrocytic aquaporin-4 (AQP4) water channels that are highly enriched in the endfeet. Even though the polarized expression of AQP4 in endfeet is thought to be of crucial importance for glymphatic CSF influx, its role in extracellular solute clearance has only been evaluated using non-quantitative fluorescence measurements. Here we have quantitatively evaluated clearance of intrastriatally infused small and large radioactively labeled solutes in mice lacking AQP4 (Aqp4) or lacking the endfoot pool of AQP4 (Snta1). We confirm that Aqp4 mice show reduced clearance of both small and large extracellular solutes. Moreover, we find that the Snta1 mice have reduced clearance only for the 500 kDa [H]dextran, but not 0.18 kDa [H]mannitol suggesting that polarization of AQP4 to the endfeet is primarily important for clearance of large, but not small molecules. Lastly, we observed that clearance of 500 kDa [H]dextran increased with age in adult mice. Based on our quantitative measurements, we confirm that presence of AQP4 is important for clearance of extracellular solutes, while the perivascular AQP4 localization seems to have a greater impact on clearance of large versus small molecules.
Topics: Animals; Mice; Aquaporin 4; Astrocytes; Brain; Dextrans; Glymphatic System
PubMed: 38532513
DOI: 10.1186/s12987-024-00527-7 -
Journal of Molecular and Cellular... May 2024Ongoing cardiomyocyte injury is a major mechanism in the progression of heart failure, particularly in dystrophic hearts. Due to the poor regenerative capacity of the...
Ongoing cardiomyocyte injury is a major mechanism in the progression of heart failure, particularly in dystrophic hearts. Due to the poor regenerative capacity of the adult heart, cardiomyocyte death results in the permanent loss of functional myocardium. Understanding the factors contributing to myocyte injury is essential for the development of effective heart failure therapies. As a model of persistent cardiac injury, we examined mice lacking β-sarcoglycan (β-SG), a key component of the dystrophin glycoprotein complex (DGC). The loss of the sarcoglycan complex markedly compromises sarcolemmal integrity in this β-SG model. Our studies aim to characterize the mechanisms underlying dramatic sex differences in susceptibility to cardiac injury in β-SG mice. Male β-SG hearts display significantly greater myocardial injury and death following isoproterenol-induced cardiac stress than female β-SG hearts. This protection of females was independent of ovarian hormones. Male β-SG hearts displayed increased susceptibility to exogenous oxidative stress and were significantly protected by angiotensin II type 1 receptor (ATR) antagonism. Increasing general antioxidative defenses or increasing the levels of S-nitrosylation both provided protection to the hearts of β-SG male mice. Here we demonstrate that increased susceptibility to oxidative damage leads to an ATR-mediated amplification of workload-induced myocardial injury in male β-SG mice. Improving oxidative defenses, specifically by increasing S-nitrosylation, provided protection to the male β-SG heart from workload-induced injury. These studies describe a unique susceptibility of the male heart to injury and may contribute to the sex differences in other forms of cardiac injury.
Topics: Animals; Male; Sarcoglycans; Female; Oxidative Stress; Cardiomyopathies; Mice; Antioxidants; Myocardium; Mice, Knockout; Myocytes, Cardiac; Disease Susceptibility; Isoproterenol; Receptor, Angiotensin, Type 1
PubMed: 38527667
DOI: 10.1016/j.yjmcc.2024.03.004