Search Results (300)

Background: Duchenne/Becker muscular dystrophy (DMD/BMD) is associated with a wide spectrum of brain-related comorbidities. Methods: This retrospective study assesses the neuropsychiatric profile of DMD/BMD patients and the hypothesis of a functional-versus-structural approach of dystrophin gene variants/impaired isoforms in relation to brain comorbidities. Patients with documented mutation in the DMD gene and neuropsychiatric assessments were included. Seven comorbidities were analyzed based on variant location and dystrophin brain isoform disruption. The clustering of comorbidities and genotype–phenotype correlations were studied. Results: 264 DMD/BMD patients met inclusion criteria. 22 variants have never been described before. A high prevalence of neuropsychiatric comorbidities was identified in the cohort with higher values in patients with distal mutations. The number of comorbidities increased with the number of brain dystrophin isoforms predicted to be lost. Functional-versus-structural comparison revealed that Dp140 5′UTR variants might not affect protein expression. Epilepsy and intellectual disability (ID) showed significant association in this cohort. Neuropsychiatric phenotype varied greatly in patients with identical variants, even between siblings. Conclusions: This is one of the largest European cohorts for which all these comorbidities were studied in association with DMD gene mutation site and the first study of this kind performed on the Eastern European DMD/BMD population. Our group analyzed, for the first time, Dp140 5′UTR variants in relation to all neuropsychiatric phenotypes and showed that epilepsy and ID are strongly associated in DMD/DMB patients. Full article

Duchenne muscular dystrophy (DMD) is a severe X-linked hereditary disorder caused by pathogenic variants in the DMD gene encoding the dystrophin protein. The absence of functional dystrophin leads to destabilization of the dystrophin-associated glycoprotein complex (DAPC), sarcolemmal damage, and progressive degeneration of muscle fibers. Current therapeutic strategies focus on restoring dystrophin expression using genome editing approaches. Adeno-associated virus (AAV) vectors represent the primary delivery platform due to their strong tropism for muscle tissue, low immunogenicity, and ability to achieve long-term transgene expression. However, the limited packaging capacity of AAV (~4.7 kb) necessitates the use of truncated mini- and micro-dystrophin transgenes as well as compact genome editing systems (SaCas9, NmeCas9, Cas12f, TIGR-Tas, and others). Major challenges include immune responses against the viral capsid and transgene products, as well as the inability to perform repeated administrations. Moreover, the duration of expression is limited by the episomal nature of AAV genomes and their loss during muscle fiber regeneration. Despite substantial progress, unresolved issues concerning safety, immunogenicity, and stability of genetic correction remain, defining the key directions for future research in DMD therapy. Full article

The way in which Aquaporin-4 (AQP4) is localized on the astrocytes’ surface—i.e., with AQP4 channels predominantly located on the endfeet of astrocytes near the blood vessels—represents an important structural element for maintaining brain fluid homeostasis. In addition to this structural function, AQP4 polarity also facilitates glymphatic transport, the maintenance of the blood–brain barrier (BBB) functions, ion buffering, and neurotransmitter removal, and helps regulate neurovascular communications. The growing body of literature suggests that the loss of AQP4 polarity—a loss in the organization of AQP4 channels to the perivascular membrane—is associated with increased vascular, inflammatory, and metabolic disturbances in the context of many neurological diseases. As a result, this review attempts to synthesize both experimental and clinical studies to highlight that AQP4 depolarization often occurs in conjunction with early signs of neurodegeneration and neuroinflammation; however, we are aware that the loss of AQP4 polarity is only one factor in a complex pathophysiological environment. This review examines the molecular structure responsible for maintaining the polarity of AQP4—such as dystrophin–syntrophin complexes, orthogonal particle arrays, lipid microdomains, trafficking pathways, and transcriptional regulators—and describes how the vulnerability of these systems to various types of vascular stress, inflammatory signals, energy deficits, and mechanical injury can lead to a loss of AQP4 polarity. Furthermore, we will explore how a loss of AQP4 polarity can lead to the disruption of perivascular fluid movement, changes in blood–brain barrier morphology, enhanced neuroimmune activity, changes in ionic and metabolic balance, and disruptions in the global neural network synchronization. Importantly, we recognize that each of these disruptions will likely occur in concert with other disease-specific mechanisms. Alterations in AQP4 polarity have been observed in a variety of neurological disorders including Alzheimer’s disease, Parkinson’s disease, multiple sclerosis, traumatic brain injury, and glioma; however, we also observe that the same alterations in fluid regulation occur across all of these different diseases, but that no single upstream event accounts for the alteration in polarity. Ultimately, we will outline emerging therapeutic avenues to restore perivascular fluid transport, and will include molecular-based therapeutic agents designed to modify the anchoring of AQP4, methods designed to modulate the state of astrocytes, biomaterials-based drug delivery systems, and therapeutic methods that leverage dynamic modulation of the neurovascular interface. Future advances in multi-omic profiling, spatial proteomics, glymphatic imaging, and artificial intelligence will allow for earlier identification of AQP4 polarity disturbances and potentially allow for the development of more personalized treatment plans. Ultimately, by linking these concepts together, this review aims to frame AQP4 polarity as a modifiable aspect of the “fluidic connectome”, and highlight its importance in maintaining overall brain health across disease states. Full article

Background: Two Shiba Inu littermates presented for investigation of marked and persistent elevation of creatine kinase activities. Method and Results: Histopathology of muscle biopsy samples revealed a dystrophic phenotype and immunostaining confirmed an absence of dystrophin protein in both cases. Whole genome sequencing of one affected dog revealed a complex deletion in the DMD gene encompassing exon 5. Screening of 27 related dogs confirmed an X-linked inheritance. The variant was identified in three related male dogs. One littermate died from cardiac arrest and the other littermate had no clinical myopathic signs at the time of the manuscript’s preparation. An additional related male dog reportedly died suddenly during grooming. Conclusion: This study adds a new breed to the canine dystrophinopathy spectrum having a ~17 kb deletion that encompasses exon 5 of DMD. This same exon 5 deletion has been identified in human dystrophin-deficient muscular dystrophy patients. Full article

Duchenne muscular dystrophy (DMD), which results from mutations that disrupt the expression of dystrophin proteins, is characterized by progressive muscle fiber wasting and the development of skeletal muscle fibrosis. The severe pathology leads to loss of ambulation, respiratory insufficiency, cardiomyopathy, and early death in patients. Dystrophin-focused therapies based on adeno-associated viral (AAV) vector-mediated gene addition, antisense oligonucleotide-induced repair of the transcript reading frame, and chemically driven stop codon readthrough have been conditionally approved for use in subsets of patients. From trials, it is apparent that these therapies act to stabilize the disease phenotype rather than improve it significantly, meaning that early treatment results in better outcomes. AAV-mediated delivery of a form of utrophin, a structural and functional homolog of dystrophin, GALGT2, a sarcolemmal stabilizer, and Klotho, the anti-aging hormone that is silenced in a mouse model of DMD as a result of the disease pathology, have been explored in preclinical compensatory gene addition studies. Recombinant follistatin protein has been used to target the fibrosis seen. An all-in-one type of therapy is likely to provide a synergistic effect such that efficacy of the dystrophin restoration strategy would be improved. For this, CRISPRa could hold potential through the targeting of multiple relevant genes simultaneously. The suitability of targeting these genes will be discussed, as will the stages of the development of CRISPRa for DMD. A perspective on the future prospects of CRISPRa in relation to likely issues that would need addressing and how they may be overcame will be given. Full article

Background/Objectives: The progressive life-limiting disorder Duchenne muscular dystrophy (DMD) arises from the absence of dystrophin protein at the muscle cell membrane, which leads to progressive contraction-induced damage. Despite the advancements in molecular therapies aimed at reintroducing (partially functional) dystrophin in patients, a cure for DMD remains elusive. Taurine supplements have been proposed as a potential supportive treatment for DMD, based upon encouraging results in the mouse model mdx. Methods: In a previous study, we observed improvements in skeletal muscle histology and a reduction in the expression of inflammatory markers after short-term treatment with 4.6 g taurine per kg body weight during the initial stages of the disease. In this follow-up study, we examined cell death and tissue restoration protein levels in mdx subjected to the same treatment regimen, utilizing proteome arrays, Western blotting, and immunofluorescence. Results: We report that, while the levels of apoptotic and autophagic proteins remained constant, selective and significant decrease in receptor-interacting Serine/Threonine protein kinase 1 (RIP1) levels could be observed in taurine-treated mdx compared to untreated mdx. RIP1 was immunolocalized to muscle fibers, with faint homogeneous staining in age-matched healthy controls shifting to a heterogeneous staining pattern in mdx, the latter diminishing with taurine treatment. Conclusions: Given its role as a molecular switch in cell fate decisions, the observed taurine-induced downregulation of RIP1 supports the potential beneficial effects of the osmolyte in mdx. Full article

Background: Type 2 diabetes (T2D) is associated with reduced cardiorespiratory fitness (CRF), a critical predictor of cardiovascular disease and all-cause mortality. CRF relies upon the coordinated action of multiple systems including the skeletal muscle where the mitochondria metabolize oxygen and substrates to sustain ATP production. Yet, previous studies have shown that impairments in muscle bioenergetics in T2D are not solely due to mitochondrial deficits. This finding indicates that factors outside the mitochondria, particularly within the local tissue microenvironment, may contribute to reduced CRF. One such factor is the extracellular matrix (ECM), which plays structural and regulatory roles in metabolic processes. Despite its potential regulatory role, the contribution of ECM remodeling to metabolic impairment in T2D remains poorly understood. We hypothesize that pathological remodeling of the skeletal muscle ECM in overweight individuals with and without T2D impairs bioenergetics and insulin sensitivity, and that exercise may help to ameliorate these effects. Methods: Participants with T2D (n = 21) and overweight controls (n = 24) completed a 10-day single-leg exercise training (SLET) intervention. Muscle samples obtained before and after the intervention were analyzed for ECM components, including collagen, elastin, hyaluronic acid, dystrophin, and proteoglycans, using second harmonic generation imaging and immunohistochemistry. Results: Positive correlations were observed with elastin content and both glucose infusion rate (p = 0.0010) and CRF (0.0363). The collagen area was elevated in participants with T2D at baseline (p = 0.0443) and showed a trend toward reduction following a 10-day SLET (p = 0.0867). Collagen mass remained unchanged, suggesting differences in density. Dystrophin levels were increased with SLET (p = 0.0256). Conclusions: These findings identify that structural proteins contribute to aerobic capacity and identify elastin as an ECM component linked to insulin sensitivity and CRF. Full article

Dystrophinopathies, including Duchenne and Becker muscular dystrophies (DMD and BMD), are inherited neuromuscular disorders frequently complicated by progressive cardiac involvement, ultimately leading to advanced heart failure. While heart transplantation and long-term left ventricular assist device (LVAD) therapy represent potential therapeutic options, their application in this population raises significant ethical challenges. This review explores the ethical implications surrounding the allocation of scarce medical resources, particularly in patients with limited life expectancy and multisystem disease, as in DMD. Decisions regarding eligibility for heart transplantation must balance individual benefit, considering the impact of excluding other potential recipients. LVAD therapy, although more accessible, still demands careful patient selection due to high perioperative risk and postoperative complications. The review emphasizes the need for transparent, multidisciplinary decision-making processes that respect patient autonomy while ensuring equitable and rational distribution of healthcare resources. Ultimately, while advanced therapies may be feasible in selected cases, particularly in BMD, ethical deliberation remains central to determining their appropriateness in the context of dystrophinopathies. Full article

Duchenne muscular dystrophy (DMD) is a severe neuromuscular disease caused by mutations in the DMD gene, leading to muscle degeneration and shortened life expectancy. Beyond motor symptoms, DMD patients frequently exhibit brain co-morbidities, linked to loss of brain-expressed dystrophin isoforms: most frequently Dp427 and Dp140, and occasionally Dp71 and Dp40. DMD mouse models, including mdx^5cv and mdx52, replicate key aspects of the human cognitive phenotype and recapitulate the main genotypic categories of brain phenotype. However, the spatio-temporal expression of brain dystrophin in mice remains poorly defined, limiting insights into how its deficiency disrupts brain development and function. We systematically mapped RNA and protein expression of brain dystrophin isoforms (Dp427 variants, Dp140, Dp71, and Dp40) across brain regions and developmental stages in wild-type mice. Dp427 isoforms were differentially expressed in the adult brain, with Dp427c enriched in the cortex, Dp427p1/p2 in the cerebellum, and Dp427m was also detected across specific brain regions. Dp140 was expressed at lower levels than Dp427; Dp71 was the most abundant isoform in adulthood. Dp140 and Dp71 displayed dynamic developmental changes, from E15 to P60, suggesting stage-specific roles. We also analysed mdx^5cv mice lacking Dp427 and mdx52 mice lacking both Dp427 and Dp140. Both models had minimal Dp427 transcript levels, likely due to the nonsense-mediated decay, and neither expressed Dp427 protein. As expected, mdx52 mice lacked Dp140, confirming their genotypic relevance to human DMD. Our study provides the first atlas of dystrophin expression in the wild-type mouse brain, aiding understanding of the anatomical basis of behavioural and cognitive comorbidities in DMD. Full article

In forensic medicine, spotting signs of an acute myocardial infarction (AMI) right after it happens is still a tough call, especially in sudden-death cases. Standard histology often misses changes in those critical first hours because the tissue damage is too subtle to see. To tackle this, we reviewed research (1990–2023) from PubMed and Web of Science, following PRISMA guidelines. We focused on studies that used immunohistochemistry to identify markers of early AMI in both human autopsies and animal models, specifically in the first six hours post-event. Our selection process narrowed 418 records to 37 key papers. We screened 49 markers in total, but only a handful stood out for reliable diagnosis: C5b-9, cardiac troponins, dystrophin, and H-FABP—all showing high specificity. Markers like S100A1 and IL-15 also showed promise, whereas JunB and connexin-43 appeared less dependable. We believe immunohistochemistry can add real value in early AMI identification, especially when using combinations of markers chosen for complementary strengths. Still, to make this approach practical in forensic settings, we need more studies on human samples and agreement on standardized lab protocols. Full article

Duchenne muscular dystrophy (DMD) is a severe X-linked recessive disorder caused by mutations in the DMD gene, leading to progressive muscle degeneration and fibrosis. A key pathological feature of DMD is mitochondrial dysfunction driven by calcium overload, which disrupts oxidative phosphorylation and triggers cell death pathways. This study shows the therapeutic potential of VBIT-4, a novel inhibitor of the mitochondrial voltage-dependent anion channel (VDAC), in two dystrophin-deficient mouse models: the mild mdx and the severe D2.DMDel8-34 strains. VBIT-4 administration (20 mg/kg) reduced mitochondrial calcium overload, enhanced resistance to permeability transition pore induction, and improved mitochondrial ultrastructure in D2.DMDel8-34 mice, while showing negligible effects in mdx mice. VBIT-4 suppressed mitochondrial and total calpain activity and reduced endoplasmic reticulum stress markers, suggesting a role in mitigating proteotoxic stress. However, it did not restore oxidative phosphorylation or reduce oxidative stress. Functional assays revealed limited improvements in muscle strength and fibrosis reduction, exclusively in the severe model. These findings underscore VDAC as a promising target for severe DMD and highlight the critical role of mitochondrial calcium homeostasis in DMD progression. Full article

Duchenne muscular dystrophy (DMD) is a lethal inherited muscle disease caused by mutations in the DMD gene, and the development of gene therapies targeting DMD is rapidly progressing. Patient-derived induced pluripotent stem cells and animal models that mimic patient-specific mutations have significantly contributed to the advancement of precision medicine based on individual genetic profiles. Currently, no approved disease-specific therapy exists for DMD cardiomyopathy, which remains one of the leading causes of death in DMD patients. Therefore, the development of effective cardiac therapies represents a critical milestone in DMD research. In this review, we provide an overview of essential cellular and animal models used in DMD research, with a specific focus on the heart. We describe their key characteristics, advantages, and limitations. It is considered that a comprehensive and strategic integration of these models—based on a clear understanding of their respective strengths and weaknesses—will be important for advancing the development and clinical application of targeted therapies for DMD cardiomyopathy. Full article

Skeletal muscle, constituting ~40% of body mass, serves as a primary effector for movement and a key metabolic regulator through myokine secretion. Hereditary myopathies, including dystrophinopathies (DMD/BMD), limb–girdle muscular dystrophies (LGMD), and metabolic disorders like Pompe disease, arise from pathogenic mutations in structural, metabolic, or ion channel genes, leading to progressive weakness and multi-organ dysfunction. Gene therapy has emerged as a transformative strategy, leveraging viral and non-viral vectors to deliver therapeutic nucleic acids. Adeno-associated virus (AAV) vectors dominate clinical applications due to their efficient transduction of post-mitotic myofibers and sustained transgene expression. Innovations in AAV engineering, such as capsid modification (chemical conjugation, rational design, directed evolution), self-complementary genomes, and tissue-specific promoters (e.g., MHCK7), enhance muscle tropism while mitigating immunogenicity and off-target effects. Non-viral vectors (liposomes, polymers, exosomes) offer advantages in cargo capacity (delivering full-length dystrophin), biocompatibility, and scalable production but face challenges in transduction efficiency and endosomal escape. Clinically, AAV-based therapies (e.g., Elevidys^® for DMD, Zolgensma^® for SMA) demonstrate functional improvements, though immune responses and hepatotoxicity remain concerns. Future directions focus on AI-driven vector design, hybrid systems (AAV–exosomes), and standardized manufacturing to achieve “single-dose, lifelong cure” paradigms for muscular disorders. Full article

The functional diversity of β-dystroglycan is attributable to its dual distribution, the plasma membrane, and the nucleus. In the plasma membrane, β-DG is a component of the dystrophin-associated protein complex. In the nucleus, β-DG assembles with the nuclear lamina and emerin. Recent findings indicate a role for β-DG in senescence, as its knockout in C2C12 myoblasts induces genomic instability and promotes the senescent state. This study analyzed the behavior of β-DG in three distinct models of senescence: chronologically aged fibroblasts, sodium butyrate (NaBu)-induced senescent fibroblasts, and fibroblasts from a Hutchinson–Gilford progeria syndrome (HGPS) patient. β-DG was found mainly in the nucleus in all the senescent cell types, with a certain mislocalization to the cytoplasm in HGPS and NaBu-treated fibroblasts. Furthermore, the full-length β-DG (43 kDa) and the cleaved intracellular domain (ICD; ~26 kDa) were identified. The ICD level increased in aged fibroblasts, but its yield was poor or virtually nonexistent in NaBU-induced and HGPS fibroblasts, respectively. Remarkably, β-DG was sequestered by progerin in HGPS cells, hindering its interaction with lamin A. In summary, the observed alterations in β-DG may be associated with the senescent state, and such findings will serve for future studies aimed at elucidating its role in senescence. Full article

Skeletal muscle regeneration requires a reliable source of myogenic progenitor cells capable of forming new fibers and creating a self-renewing satellite cell pool. Human induced pluripotent stem cell (hiPSC)-derived teratomas have emerged as a novel in vivo platform for generating skeletal myogenic progenitors, although in vivo studies to date have provided only an early single-time-point snapshot. In this study, we isolated a specific population of CD82⁺ ERBB3⁺ NGFR⁺ cells from human iPSC-derived teratomas and verified their long-term in vivo regenerative capacity following transplantation into NSG-mdx^4Cv mice. Transplanted cells engrafted, expanded, and generated human Dystrophin⁺ muscle fibers that increased in size over time and persisted stably long-term. A dynamic population of PAX7⁺ human satellite cells was established, initially expanding post-transplantation and declining moderately between 4 and 8 months as fibers matured. MyHC isoform analysis revealed a time-based shift from embryonic to neonatal and slow fiber types, indicating a slow progressive maturation of the graft. We further show that these progenitors can be cryopreserved and maintain their engraftment potential. Together, these findings give insight into the evolution of teratoma-derived human myogenic stem cell grafts, and highlight the long-term regenerative potential of teratoma-derived human skeletal myogenic progenitors. Full article