Treatment Of Duchenne Muscular Dystrophy Patients Research Articles

Antioxidants for Treatment of Duchenne Muscular Dystrophy: A Systematic Review and Meta-Analysis

Introduction: Increasing evidence has shown that oxidative stress is involved in the pathogenesis of Duchenne muscular dystrophy (DMD). Oxidative stress impairs muscle function, reduces regenerative capacity, and leads to atrophy and muscle weakness. The present study aimed to evaluate the effectiveness and safety of antioxidants in treatment of DMD patients. Methods: Medline, Embase, EBSCOhost, and Cochrane Library databases were searched using relevant keywords regarding DMD and antioxidants. The risk of bias for all included studies was assessed using the Cochrane risk of bias tool. The effectiveness of antioxidants in improving pulmonary function and muscle strength in DMD patients and their rate of adverse events was evaluated by meta-analysis. Results: A total of nine eligible studies were identified. Among these, two studies involving 85 patients compared idebenone with placebo. Pooled data showed a significant improvement in pulmonary function after idebenone treatment. Flavonoids- and omega 3-based compounds (FLAVOMEGA) significantly improved muscle strength. Two studies evaluated coenzyme Q₁₀ (CoQ₁₀) and reported clinical improvement in physical activity. The remaining four studies evaluated pentoxifylline, superoxide dismutase, vitamin E combination with penicillamine and penicillamine alone, respectively, and found no significant differences between the intervention and placebo groups, measured by pulmonary function, muscle strength, movement function, or quality of life. Most adverse events were mild, while the rates of dropout and serious adverse events were low with respect to antioxidants. Conclusions: Idebenone appeared to be safe and effective in improving pulmonary function in DMD patients, while pentoxifylline, superoxide dismutase, penicillamine, or a combination of vitamin E with penicillamine did not show a significant therapeutic effect. CoQ₁₀ and FLAVOMEGA might be beneficial in improving muscle strength or physical activity in DMD patients. However, additional trials with more participants are warranted in the future.

Sertoli Cells Improve Myogenic Differentiation, Reduce Fibrogenic Markers, and Induce Utrophin Expression in Human DMD Myoblasts.

Duchenne muscular dystrophy (DMD) is an X-linked disease caused by mutations in DMD gene translating in lack of functional dystrophin and resulting in susceptibility of myofibers to rupture during contraction. Inflammation and fibrosis are critical hallmarks of DMD muscles, which undergo progressive degeneration leading to loss of independent ambulation in childhood and death by early adulthood. We reported that intraperitoneal injection of microencapsulated Sertoli cells (SeC) in dystrophic mice translates into recovery of muscle morphology and performance thanks to anti-inflammatory effects and induction of the dystrophin paralogue, utrophin at the muscle level, opening new avenues in the treatment of DMD. The aim of this study is to obtain information about the direct effects of SeC on myoblasts/myotubes, as a necessary step in view of a translational application of SeC-based approaches to DMD. We show that (i) SeC-derived factors stimulate cell proliferation in the early phase of differentiation in C2C12, and human healthy and DMD myoblasts; (ii) SeC delay the expression of differentiation markers in the early phase nevertheless stimulating terminal differentiation in DMD myoblasts; (iii) SeC restrain the fibrogenic potential of fibroblasts, and inhibit myoblast-myofibroblast transdifferentiation; and, (iv) SeC provide functional replacement of dystrophin in preformed DMD myotubes regardless of the mutation by inducing heregulin β1/ErbB2/ERK1/2-dependent utrophin expression. Altogether, these results show that SeC are endowed with promyogenic and antifibrotic effects on dystrophic myoblasts, further supporting their potential use in the treatment of DMD patients. Our data also suggest that SeC-based approaches might be useful in improving the early phase of muscle regeneration, during which myoblasts have to adequately proliferate to replace the damaged muscle mass.

Electrostatic Coating of Viral Particles for Gene Delivery Applications in Muscular Dystrophies: Influence of Size on Stability and Antibody Protection

Duchenne Muscular Dystrophy (DMD) is one of the most common muscular dystrophies, caused by mutated forms of the dystrophin gene. Currently, the only treatment available is symptoms management. Novel approximations are trying to treat these patients with gene therapy, namely, using viral vectors. However, these vectors can be recognized by the immune system decreasing their therapeutic activity and making impossible a multidose treatment due to the induction of the humoral immunity following the first dose. Our objective is to demonstrate the feasibility of using a hybrid vector to avoid immune clearance, based on the electrostatic coating of adeno-associated virus (AAVs) vectors with our proprietary polymers. We coated model adeno-associated virus vectors by electrostatic interaction of our cationic poly (beta aminoester) polymers with the viral anionic capsid and characterized biophysical properties. Once the nanoformulations were designed, we studied their in vivo biodistribution by bioluminescence analysis and we finally studied the capacity of the polymers as potential coatings to avoid antibody neutralization. We tested two polymer combinations and we demonstrated the need for poly(ethylene glycol) addition to avoid vector aggregation after coating. In vivo biodistribution studies demonstrated that viral particles are located in the liver (short times) and also in muscles (long times), the target organ. However, we did not achieve complete antibody neutralization shielding using this electrostatic coating. The null hypothesis stands: although it is feasible to coat viral particles by electrostatic interaction with a proprietary polymer, this strategy is not appropriate for AAVs due to their small size, so other alternatives are required as a novel treatment for DMD patients.

Expert recommendation: treatment of nonambulatory patients with Duchenne muscular dystrophy

HintergrundDie Muskeldystrophie Duchenne (DMD) ist die häufigste genetische neuromuskuläre Krankheit im Kindesalter, bei der es meist im Alter von 9 bis 11 Jahren zum Verlust der Gehfähigkeit kommt.Ziel der Arbeit und Material und MethodenAuf der Grundlage aktueller Leitlinien und Studien erarbeiteten neuropädiatrische und neurologische Experten im Rahmen eines von der Firma PTC Therapeutics GmbH (Frankfurt am Main, Deutschland), die die Substanz Ataluren vertreibt, gesponserten Advisory Boards Empfehlungen zur Behandlung nichtgehfähiger Patienten mit DMD mit Schwerpunkt medikamentöse Therapien von Erwachsenen.Ergebnisse und DiskussionDer Verlust der Gehfähigkeit wird in Studien sehr unterschiedlich definiert und bezieht sich u. a. auf die Rollstuhlpflicht, das selbständige Gehen ohne Hilfsmittel oder die maximale Gehstrecke. Grundlage der Therapie von Patienten mit DMD in jedem Krankheitsstadium sind supportive und symptomatische Maßnahmen, die in der Regel auch nach dem Verlust der Gehfähigkeit intensiv weitergeführt werden sollten. Zusätzlich stehen den Patienten medikamentöse Therapien mit dem Ziel der Modifikation des Krankheitsverlaufes zur Verfügung. Glukokortikoide bilden den Stützpfeiler der medikamentösen Therapie auch über den Verlust der Gehfähigkeit hinaus, dann meist in reduzierter Dosis. Für Patienten mit DMD aufgrund einer Nonsense-Mutation (nmDMD), ca. 13 % aller DMD-Patienten, steht Ataluren als potenziell dystrophinwiederherstellende, krankheitsmodifizierende Therapie zur Verfügung; klinische Daten aus dem STRIDE-Register zeigen eine verzögerte Krankheitsprogression auch nach Verlust der Gehfähigkeit. Zum Exon-Skipping liegen für erwachsene Patienten derzeit noch keine belastbaren Daten vor. Das Antioxidans Idebenon kommt bei nichtgehfähigen, jugendlichen Patienten ohne therapeutische Alternative, die nicht mit Glukokortikoiden behandelt werden können, infrage. Ataluren eignet sich zur kombinierten Behandlung mit Glukokortikoiden, eine Kombination von Idebenon und Glukokortikoiden wird derzeit in einer klinischen Studie überprüft. Eine Add-on-Therapie mit Idebenon zusätzlich zu Ataluren ist bei nichtgehfähigen nmDMD-Patienten zu erwägen. Bedingt durch die Tatsache, dass sich einige der diskutierten Therapieoptionen noch in der Phase der klinischen Prüfung befinden oder noch keine oder nur begrenzte Daten für ältere Patienten mit DMD vorliegen, handelt es sich um Expertenempfehlungen entsprechend der Evidenzklasse IV.

Janus effect of glucocorticoids on differentiation of muscle fibro/adipogenic progenitors

Muscle resident fibro-adipogenic progenitors (FAPs), support muscle regeneration by releasing cytokines that stimulate the differentiation of myogenic stem cells. However, in non-physiological contexts (myopathies, atrophy, aging) FAPs cause fibrotic and fat infiltrations that impair muscle function. We set out to perform a fluorescence microscopy-based screening to identify compounds that perturb the differentiation trajectories of these multipotent stem cells. From a primary screen of 1,120 FDA/EMA approved drugs, we identified 34 compounds as potential inhibitors of adipogenic differentiation of FAPs isolated from the murine model (mdx) of Duchenne muscular dystrophy (DMD). The hit list from this screen was surprisingly enriched with compounds from the glucocorticoid (GCs) chemical class, drugs that are known to promote adipogenesis in vitro and in vivo. To shed light on these data, three GCs identified in our screening efforts were characterized by different approaches. We found that like dexamethasone, budesonide inhibits adipogenesis induced by insulin in sub-confluent FAPs. However, both drugs have a pro-adipogenic impact when the adipogenic mix contains factors that increase the concentration of cAMP. Gene expression analysis demonstrated that treatment with glucocorticoids induces the transcription of Gilz/Tsc22d3, an inhibitor of the adipogenic master regulator PPARγ, only in anti-adipogenic conditions. Additionally, alongside their anti-adipogenic effect, GCs are shown to promote terminal differentiation of satellite cells. Both the anti-adipogenic and pro-myogenic effects are mediated by the glucocorticoid receptor and are not observed in the presence of receptor inhibitors. Steroid administration currently represents the standard treatment for DMD patients, the rationale being based on their anti-inflammatory effects. The findings presented here offer new insights on additional glucocorticoid effects on muscle stem cells that may affect muscle homeostasis and physiology.

Muscular Dystrophy and Rehabilitation Interventions with Regenerative Treatment

This paper reviews the enhanced therapeutic effects of rehabilitation and regenerative medicine toward Duchenne muscular dystrophy. Duchenne muscular dystrophy (DMD) is one of the most severe forms of muscle disorders. Muscle in DMD patients is extremely fragile and can be damaged even during normal daily activity. There is little in the way of treatment for the disease and no cure. Some investigators have been developing cell therapies for DMD by generating muscle stem cells from human-induced pluripotent stem (iPS) cells and other progenitor/stem cells. Although reports have shown dystrophin protein restoration following cell transplantation in DMD models, improvement in motor function has not been achieved, and optimal methods that maximize the efficacy of the transplantation are still needed. Recently, some studies have reported that exercise with controlled load (treadmill running, voluntary running on a running wheel, swimming, etc.) improves the pathology of DMD. Thus, exercise is expected to enhance the effect of cell therapy for DMD, acting as a form of “regenerative rehabilitation.” Consistently, optimized muscle contraction training programs enhance the effect of cell transplantation therapy. Cell transplantation therapy in combination with rehabilitation, which focuses on exercise therapy, may provide an effective radical treatment for DMD patients. This combination is described as regenerative rehabilitation.

DMD CLINICAL THERAPIES I: P.119Tamoxifen in Duchenne muscular dystrophy: rationale and protocol for a multicentre, randomised, double-blind, placebo-controlled, phase 3 safety and efficacy 48-week trial

Most current research on therapeutics of Duchenne muscular dystrophy (DMD) focuses on correcting the gene defect. However, as there are more than 250 mutations in the human dystrophin gene, this approach will treat only a small percentage of patients and will be expensive. Using the mouse DMD model it could be shown that tamoxifen (TAM), given orally for periods of 2 or 15 months, results in almost full recovery of force and structure of muscles. TAM is one of the most efficacious drugs ever investigated in an animal model of DMD. Our aim is to investigate whether TAM treatment, compared to placebo, reduces the disease progression in DMD patients. We are setting up an international (France, Germany, Greece, Spain, Switzerland, United Kingdom, The Netherlands, Turkey) randomised double blind placebo controlled 48-week clinical trial with a core population (group A) of 79 ambulant 6.5 to 12 years old DMD patients that are on a stable standard treatment with glucocorticoids. Parallel we will include 16-20 non-ambulant patients age 10 to 16 years who do not receive glucocorticoids (group B) to obtain efficacy and safety data in a broader DMD population. All patients will receive 20 mg of TAM or placebo once daily over 48 weeks. The primary outcome for group A is the motor function measure (MFM) D1. In group B the MFM D2 is the primary endpoint, allowing extrapolation of MFM D2 data from the group A population. In addition, to investigate whether longterm TAM treatment can slow muscle degeneration, quantitative thigh muscle magnetic resonance imaging will be performed. The study aims to describe an efficacy and safety profile for tamoxifen in the treatment of DMD patients. The purpose of this study is to evaluate if TAM shows positive effects on muscle function and muscle force in comparison to placebo in DMD-patients. Recruitment is expected to start in June 2018.

617. Histologic Assessment of Geriatric Esophagus Revels Therapeutic Targets in Wild-Type and Dystrophic Mouse Models

Gastroesophageal disorders increase as a process of aging and are exacerbated in degenerative neuromuscular disease such as Duchenne muscular dystrophy (DMD). DMD affects ≈1/5000 male births and is a catastrophic and ultimately fatal muscle wasting disease resulting from a mutation in the gene encoding the integral muscle protein dystrophin. Advancements in the treatment for DMD patients has increased patient lifespan and underscores a need to assess the impact of the disease in a range of organ systems, including the esophagus, likely to present new therapeutic challenges over time. Severity of esophageal pathology is varied to include reflux disease, achalasia, and megaesophagus. Defined as a pathologic enlargement of the esophagus, megaesophagus can result in a failure to complete peristalsis, impaction, severe weight loss and increased morbidity. Although poorly defined in human DMD patients, megaesophagus has been documented in canine and mouse models of DMD, however, a detailed cellular and mechanistic understanding remains unclear. We have performed a comprehensive morphologic and histologic examination of wild-type (C57/BL6) and dystrophic (mdx4cv) mouse esophagus to determine onset, pathology and changes in cellular composition accompanying megaesophagus onset. Age-associated presentation of megaesophagus was highly penetrant in both mouse models, with a four-fold increase in lumen dilation and coincident rate of impaction seen in aged dystrophic mice. In comparison, skeletal muscle area increased in both models with age, however, wild-type mice presented significantly greater hypertrophy than that observed in dystrophic mice. Interestingly, strain specific differences were not identified in esophagus mucosa strata with both strains presenting significant and similar increases in mucosa area and aging-dependent changes in mucosa composition. Further, a pronounced, aging-specific degradation of smooth musculature was observed in both mouse strains independent of dystrophin expression within wild-type mice. We demonstrate that esophageal smooth muscle is targetable via AAV-mediated gene therapy with future efforts aimed at correcting degeneration present within geriatric wild-type and dystrophic mouse models.

Treatment with a nitric oxide‐donating NSAID counteracts functional muscle ischemia in dystrophin‐deficient mdx mice

The dystrophin‐deficient muscles of boys with Duchenne muscular dystrophy (DMD) and mdx mice, a model of DMD, are susceptible to ischemia during exercise due to loss of neuronal nitric oxide synthase (nNOS) from the sarcolemma. We hypothesized that treatment with a NO‐donating drug would compensate for nNOS deficiency and counteract functional muscle ischemia. We fed mdx mice a standard diet containing 1% soybean oil (vehicle) or a low (15 mg/kg) or high (45 mg/kg) dose of a NO‐releasing derivative of the NSAID flurbiprofen (n = 12/group). After 1 month of treatment, we compared vasoconstrictor responses to intra‐arterial norepinephrine (NE) in resting and contracting hindlimbs. In vehicle‐treated mice, the usual effect of muscle contraction to attenuate NE‐mediated vasoconstriction was impaired as shown by similar decreases in femoral vascular conductance in contracting vs resting hindlimbs (attenuation ratio = 0.88 ± 0.03). NE‐induced ischemia was also seen in the contracting hindlimbs of mice treated with low dose drug (0.92 ± 0.04; P > 0.05 vs vehicle), but was markedly attenuated in mice treated with high dose drug (0.22 ± 0.03; P < 0.05 vs vehicle or low dose). The beneficial effect of the high dose was maintained with treatment up to 3 months. These data demonstrate a robust anti‐ischemic effect of a NO‐donating drug in mdx mice and suggest a potential use in the treatment of DMD patients. Supported by NicOx, 801130.

Effect of Sildenafil on mdx Skeletal Muscle

Duchenne muscular dystrophy (DMD) affects 1 in 3,500 boys and is a severe X‐linked disease caused by a complete loss of dystrophin. DMD patients are born healthy but by age five, develop progressive skeletal muscle necrosis, fibrosis and abnormal hypertrophy. Sildenafil Citrate (Viagra®) is a phosphodiesterase 5 (PDE5) inhibitor that induces vasodilation and is currently approved for use in treatment of erectile dysfunction and pulmonary hypertension.Previous studies have shown Sildenafil activates PKG‐1, resulting in anti‐hypertrophic and anti‐fibrotic effects on pressure‐induced cardiac hypertrophy (Takimoto et al (2005) Nature 11(2):214–222). Recently, another PDE5 inhibitor, tadalafil, has been reported to be effective in ameliorating some of the dystrophic symptoms in the mdx mouse, a dystrophin knockout model of DMD (Asai et al (2007) PLoS ONE 2(8): e806). We have been exploring the use of non‐invasive techniques such as echocardiography and MRI, to track the progression of Sildenafil treatment throughout the life of the mdx mouse. After one year of chronic Sildenafil treatment, we see a decrease in the MRI T2 relaxation time of the hind‐leg muscle, indicating a decrease in dystrophic tissue. Earlier times also show a trend toward beneficial effect. With eight weeks of treatment, there is a decrease in Tibialis Anterior muscle atrophy and centrinucleation, thus less overall damage and a decrease in the need for muscle regeneration. This data provides preliminary evidence that PDE5 regulation can reduce muscle damage in skeletal dystrophic muscle indicating Sildenafil could be a possible treatment for DMD patients. Supported by Charley's Fund and NIH grant DK21623.