Search Results (54)

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

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

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 severe X-linked disorder characterized by progressive muscle degeneration due to mutations in the dystrophin gene. Despite major advancements in understanding its pathophysiology, there is still no curative treatment. This review provides an up-to-date overview of current and emerging therapeutic approaches—including antisense oligonucleotides, gene therapy, gene editing, corticosteroids, and histone deacetylases(HDAC) inhibitors—aimed at restoring dystrophin expression or mitigating disease progression. Special emphasis is placed on the importance of early diagnosis, the utility of genetic screening, and the innovations in pre-and post-natal testing. As the field advances toward personalized medicine, the integration of precision therapies with cutting-edge diagnostic technologies promises to improve both prognosis and quality of life for individuals with DMD. Full article

Duchenne muscular dystrophy (DMD) is a severe inherited muscle-wasting disorder that is associated with severe morbidity and mortality globally. Current treatment options have improved the quality of life of patients, but these treatments are only palliative. There is a need for more DMD treatment options. Antisense oligonucleotide (ASO) therapies have emerged as a promising personalized treatment option for patient groups that possess specific mutations. A subset of these therapies can skip over frame-disrupting exons in the DMD gene and can partially restore dystrophin production for individuals with DMD. One novel exon skipping therapy currently being investigated is brogidirsen, an exon 44 that targets ASO using a novel dual-targeting approach. This article will provide an overview of brogidirsen’s history and current clinical trial developments. It will summarize how this investigational therapy compares with other pre-clinical and clinical trial-stage ASO therapies targeting exon 44. Current advances and challenges faced by RNA-based therapies will also be discussed. Overall, brogidirsen is a promising potential addition to existing DMD treatment options, with its clinical trial results showing expression levels above that of the maximum amount of dystrophin expression achieved by current FDA- and EMA-approved exon-skipping DMD therapies. Further research will be needed to determine its overall efficacy and ability to overcome the known limitations faced by other existing ASO therapies. Full article

Duchenne muscular dystrophy (DMD) is a severe genetic disorder characterized by the progressive degeneration of skeletal and cardiac muscles due to the absence of dystrophin. Exon-skipping therapy is among the most promising approaches for treating DMD, with several antisense oligonucleotides (ASO) already approved by the FDA; however, their limited efficacy highlights substantial potential for further improvement. In this study, we evaluate the potential of combining ASO with valproic acid (VPA) to enhance dystrophin expression and improve functional outcomes in a murine model of DMD. Our results indicate that the ASO+VPA treatment significantly increases dystrophin restoration across various muscle tissues, with particularly pronounced effects observed in cardiac muscle, where levels are nearly doubled compared to ASO monotherapy. Additionally, we demonstrate significant improvements in functional outcomes in treated mdx mice. Our findings suggest that the combined ASO+VPA therapy holds promise as an effective therapeutic approach to ameliorate muscle function in DMD, warranting further exploration of its mechanistic pathways and long-term benefits. Full article

Thirty years ago, in 1995, I proposed a fundamental treatment for Duchenne Muscular Dystrophy (DMD) using antisense oligonucleotides (ASOs) to induce exon skipping and restore dystrophin expression. DMD is a progressive and fatal muscular dystrophy, and the establishment of an effective therapy has been a pressing demand among patients worldwide. Exon-skipping therapy utilizing ASOs has garnered significant attention as one of the most promising treatments for DMD, stimulating global research and development efforts in ASO technology. Two decades later, in 2016, one ASO was conditionally approved by the U.S. FDA as the first DMD treatment. This review summarizes the current status and challenges of ASO-based exon-skipping therapies for DMD and explores the prospects of pseudoexon skipping using ASOs, which holds the potential for achieving a complete cure for DMD. Full article

Background/Objectives: Antisense oligonucleotide (ASO)-mediated exon-skipping is an effective approach to restore the disrupted reading frame of the dystrophin gene for the treatment of Duchenne muscular dystrophy (DMD). Currently, four FDA-approved ASOs can target three different exons, but these therapies are mutation-specific and only benefit a subset of patients. Understanding the broad applicability of exon-skipping approaches is essential for prioritizing the development of additional therapies with the greatest potential impact on the DMD population. This review offers an updated analysis of all theoretical exon-skipping strategies and their applicability across the patient population, with a specific focus on DMD-associated mutations documented in the UMD-DMD database. Unlike previous studies, this approach leverages the inclusion of phenotypic data for each mutation, providing a more comprehensive and clinically relevant perspective. Methods: The theoretical applicability of all single and double exon-skipping strategies, along with multi exon-skipping strategies targeting exons 3–9 and 45–55, was evaluated for all DMD mutations reported in the UMD-DMD database. Results: Single and double exon-skipping approaches were applicable for 92.8% of large deletions, 93.7% of small lesions, 72.4% of duplications, and 90.3% of all mutations analyzed. Exon 51 was the most relevant target and was applicable for 10.6% of all mutations and 17.2% of large deletions. Additionally, two multi-exon-skipping approaches, targeting exons 45–55 and 3–9, were relevant for 70.6% of large deletions and 19.2% of small lesions. Conclusions: Current FDA-approved ASOs were applicable to 27% of the UMD-DMD population analyzed, leaving a significant portion of patients without access to exon-skipping therapies. The clinical translation of alternative approaches is critical to expanding the accessibility of these therapies for the DMD population. Full article

Duchenne muscular dystrophy (DMD) is a degenerative neuromuscular disease caused by a lack of functional dystrophin. Ang 1 paracrine signalling maintains the endothelial barrier of blood vessels, preventing plasma leakage. Chronic inflammation, a consequence of DMD, causes endothelial barrier dysfunction in skeletal muscle. We aim to elucidate changes in the DMD mouse’s gastrocnemius microvascular niche following local administration of Ang 1. Gastrocnemii were collected from eight-week-old mdx/utrn+/− and healthy mice. Additional DMD cohort received an intramuscular injection of Ang 1 to gastrocnemius and contralateral control. Gastrocnemii were collected for analysis after two weeks. Using immunohistochemistry and real-time quantitative reverse transcription, we demonstrated an abundance of endothelial cells in DMD mouse’s gastrocnemius, but morphology and gene expression were altered. Myofiber perimeters were shorter in DMD mice. Following Ang 1 treatment, fewer endothelial cells were present, and microvessels were more circular. Vegfr1, Vegfr2, and Vegfa expression in Ang 1-treated gastronemii increased, while myofiber size distribution was consistent with vehicle-only gastrocnemii. These results suggest robust angiogenesis in DMD mice, but essential genes were underexpressed—furthermore, exogenous Ang 1 attenuated angiogenesis. Consequentially, gene expression increased. The impact must be investigated further, as Ang 1 therapy may be pivotal in restoring the skeletal muscle microvascular niche. Full article

Significant progress has been achieved in understanding Duchenne muscular dystrophy (DMD) mechanisms and developing treatments to slow disease progression. This review article thoroughly assesses primary and secondary DMD therapies, focusing on innovative modalities. The primary therapy addresses the genetic abnormality causing DMD, specifically the absence or reduced expression of dystrophin. Gene replacement therapies, such as exon skipping, readthrough, and gene editing technologies, show promise in restoring dystrophin expression. Adeno-associated viruses (AAVs), a recent advancement in viral vector-based gene therapies, have shown encouraging results in preclinical and clinical studies. Secondary therapies aim to maintain muscle function and improve quality of life by mitigating DMD symptoms and complications. Glucocorticoid drugs like prednisone and deflazacort have proven effective in slowing disease progression and delaying loss of ambulation. Supportive treatments targeting calcium dysregulation, histone deacetylase, and redox imbalance are also crucial for preserving overall health and function. Additionally, the review includes a detailed table of ongoing and approved clinical trials for DMD, exploring various therapeutic approaches such as gene therapies, exon skipping drugs, utrophin modulators, anti-inflammatory agents, and novel compounds. This highlights the dynamic research field and ongoing efforts to develop effective DMD treatments. Full article

In recent years, clustered regularly interspaced short palindromic repeats (CRISPRs) and CRISPR-associated (Cas) protein have emerged as a revolutionary gene editing tool to treat inherited disorders affecting different organ systems, such as blood and muscles. Both hematological and neuromuscular genetic disorders benefit from genome editing approaches but face different challenges in their clinical translation. The ability of CRISPR/Cas9 technologies to modify hematopoietic stem cells ex vivo has greatly accelerated the development of genetic therapies for blood disorders. In the last decade, many clinical trials were initiated and are now delivering encouraging results. The recent FDA approval of Casgevy, the first CRISPR/Cas9-based drug for severe sickle cell disease and transfusion-dependent β-thalassemia, represents a significant milestone in the field and highlights the great potential of this technology. Similar preclinical efforts are currently expanding CRISPR therapies to other hematologic disorders such as primary immunodeficiencies. In the neuromuscular field, the versatility of CRISPR/Cas9 has been instrumental for the generation of new cellular and animal models of Duchenne muscular dystrophy (DMD), offering innovative platforms to speed up preclinical development of therapeutic solutions. Several corrective interventions have been proposed to genetically restore dystrophin production using the CRISPR toolbox and have demonstrated promising results in different DMD animal models. Although these advances represent a significant step forward to the clinical translation of CRISPR/Cas9 therapies to DMD, there are still many hurdles to overcome, such as in vivo delivery methods associated with high viral vector doses, together with safety and immunological concerns. Collectively, the results obtained in the hematological and neuromuscular fields emphasize the transformative impact of CRISPR/Cas9 for patients affected by these debilitating conditions. As each field suffers from different and specific challenges, the clinical translation of CRISPR therapies may progress differentially depending on the genetic disorder. Ongoing investigations and clinical trials will address risks and limitations of these therapies, including long-term efficacy, potential genotoxicity, and adverse immune reactions. This review provides insights into the diverse applications of CRISPR-based technologies in both preclinical and clinical settings for monogenic blood disorders and muscular dystrophy and compare advances in both fields while highlighting current trends, difficulties, and challenges to overcome. Full article

A deficiency in the shortest dystrophin-gene product, Dp71, is a pivotal aggravating factor for intellectual disabilities in Duchenne muscular dystrophy (DMD). Recent advances in preclinical research have achieved some success in compensating both muscle and brain dysfunctions associated with DMD, notably using exon skipping strategies. However, this has not been studied for distal mutations in the DMD gene leading to Dp71 loss. In this study, we aimed to restore brain Dp71 expression in the Dp71-null transgenic mouse using an adeno-associated virus (AAV) administrated either by intracardiac injections at P4 (ICP4) or by bilateral intracerebroventricular (ICV) injections in adults. ICP4 delivery of the AAV9-Dp71 vector enabled the expression of 2 to 14% of brain Dp71, while ICV delivery enabled the overexpression of Dp71 in the hippocampus and cortex of adult mice, with anecdotal expression in the cerebellum. The restoration of Dp71 was mostly located in the glial endfeet that surround capillaries, and it was associated with partial localization of Dp71-associated proteins, α1-syntrophin and AQP4 water channels, suggesting proper restoration of a scaffold of proteins involved in blood–brain barrier function and water homeostasis. However, this did not result in significant improvements in behavioral disturbances displayed by Dp71-null mice. The potential and limitations of this AAV-mediated strategy are discussed. This proof-of-concept study identifies key molecular markers to estimate the efficiencies of Dp71 rescue strategies and opens new avenues for enhancing gene therapy targeting cognitive disorders associated with a subgroup of severely affected DMD patients. Full article

Duchenne muscular dystrophy (DMD) is a genetic progressive muscle-wasting disorder that leads to rapid loss of mobility and premature death. The absence of functional dystrophin in DMD patients reduces sarcolemma stiffness and increases contraction damage, triggering a cascade of events leading to muscle cell degeneration, chronic inflammation, and deposition of fibrotic and adipose tissue. Efforts in the last decade have led to the clinical approval of novel drugs for DMD that aim to restore dystrophin function. However, combination therapies able to restore dystrophin expression and target the myriad of cellular events found impaired in dystrophic muscle are desirable. Muscles are higher energy consumers susceptible to mitochondrial defects. Mitochondria generate a significant source of reactive oxygen species (ROS), and they are, in turn, sensitive to proper redox balance. In both DMD patients and animal models there is compelling evidence that mitochondrial impairments have a key role in the failure of energy homeostasis. Here, we highlighted the main aspects of mitochondrial dysfunction and oxidative stress in DMD and discussed the recent findings linked to mitochondria/ROS-targeted molecules as a therapeutic approach. In this respect, dual targeting of both mitochondria and redox homeostasis emerges as a potential clinical option in DMD. Full article