Death after High-Dose rAAV9 Gene Therapy in a Patient with Duchenne's Muscular Dystrophy.

We treated a 27-year-old patient with Duchenne's muscular dystrophy (DMD) with recombinant adeno-associated virus (rAAV) serotype 9 containing dCas9 (i.e., "dead" Cas9, in which the Cas9 nuclease activity has been inactivated) fused to VP64; this transgene was designed to up-regulate cortical dystrophin as a custom CRISPR-transactivator therapy.

PDE10A Inhibition Reduces the Manifestation of Pathology in DMD Zebrafish and Represses the Genetic Modifier PITPNA.

Duchenne muscular dystrophy (DMD) is a severe genetic disorder caused by mutations in the DMD gene. Absence of dystrophin protein leads to progressive degradation of skeletal and cardiac function and leads to premature death. Over the years, zebrafish have been increasingly used for studying DMD and are a powerful tool for drug discovery and therapeutic development.

Effect of serotonin modulation on dystrophin-deficient zebrafish.

Duchenne muscular dystrophy (DMD) is a progressive muscle-wasting disease caused by mutation of the gene. Pharmacological therapies that function independently of dystrophin and complement strategies aimed at dystrophin restoration could significantly improve patient outcomes. Previous observations have suggested that serotonin pathway modulation ameliorates dystrophic pathology, and re-application of serotonin modulators already used clinically would potentially hasten availability to DMD patients.

Purification of Myogenic Progenitors from Human Muscle Using Fluorescence-Activated Cell Sorting (FACS).

Primary myoblasts derived from human tissue are a valuable tool in research of muscle disease and pathophysiology. However, skeletal muscle biopsies, especially from diseased muscle, contain a plethora of non-myogenic cells, necessitating purification of the myogenic cell population. This protocol describes techniques for dissociation of cells from human skeletal muscle biopsies and enrichment for a highly myogenic population by fluorescence-activated cell sorting (FACS).

Isolation of Primary Human Skeletal Muscle Cells.

Primary myoblast culture is a valuable tool in research of muscle disease, pathophysiology, and pharmacology. This protocol describes techniques for dissociation of cells from human skeletal muscle biopsies and enrichment for a highly myogenic population by fluorescence-activated cell sorting (FACS). We also describe methods for assessing myogenicity and population expansion for subsequent study.

Repression of phosphatidylinositol transfer protein α ameliorates the pathology of Duchenne muscular dystrophy.

Duchenne muscular dystrophy (DMD) is a progressive muscle wasting disease caused by X-linked inherited mutations in the () gene. Absence of dystrophin protein from the sarcolemma causes severe muscle degeneration, fibrosis, and inflammation, ultimately leading to cardiorespiratory failure and premature death. Although there are several promising strategies under investigation to restore dystrophin protein expression, there is currently no cure for DMD, and identification of genetic modifiers as potential targets represents an alternative therapeutic strategy.

Exosomal Small Talk Carries Strong Messages from Muscle Stem Cells.

Exosome-dependent intercellular communication is an emerging signaling mechanism involved in tissue repair and regeneration. Now in this issue of Cell Stem Cell, Fry et al. (2016) show that muscle stem cells communicate with fibrogenic cells by exosomal trafficking of microRNA-206 to regulate extracellular matrix deposition and muscle tissue remodeling.

CD82 Is a Marker for Prospective Isolation of Human Muscle Satellite Cells and Is Linked to Muscular Dystrophies.

Cell-surface markers for prospective isolation of stem cells from human skeletal muscle have been difficult to identify. Such markers would be powerful tools for studying satellite cell function during homeostasis and in pathogenesis of diseases such as muscular dystrophies. In this study, we show that the tetraspanin KAI/CD82 is an excellent marker for prospectively isolating stem cells from human fetal and adult skeletal muscle.

Pharmacological therapeutics targeting the secondary defects and downstream pathology of Duchenne muscular dystrophy.

Introduction: Since the identification of the dystrophin gene in 1986, a cure for Duchenne muscular dystrophy (DMD) has yet to be discovered. Presently, there are a number of genetic-based therapies in development aimed at restoration and/or repair of the primary defect. However, growing understanding of the pathophysiological consequences of dystrophin absence has revealed several promising downstream targets for the development of therapeutics.

Masticatory muscles of mouse do not undergo atrophy in space.

Muscle loading is important for maintaining muscle mass; when load is removed, atrophy is inevitable. However, in clinical situations such as critical care myopathy, masticatory muscles do not lose mass. Thus, their properties may be harnessed to preserve mass.

Gamma-sarcoglycan is required for the response of archvillin to mechanical stimulation in skeletal muscle.

Loss of gamma-sarcoglycan (γ-SG) induces muscle degeneration and signaling defects in response to mechanical load, and its absence is common to both Duchenne and limb girdle muscular dystrophies. Growing evidence suggests that aberrant signaling contributes to the disease pathology; however, the mechanisms of γ-SG-mediated mechanical signaling are poorly understood. To uncover γ-SG signaling pathway components, we performed yeast two-hybrid screens and identified the muscle-specific protein archvillin as a γ-SG and dystrophin interacting protein.

Mature IGF-I excels in promoting functional muscle recovery from disuse atrophy compared with pro-IGF-IA.

Prolonged disuse of skeletal muscle results in atrophy, and once physical activity is resumed, there is increased susceptibility to injury. Insulin-like growth factor-I (IGF-I) is considered a potential therapeutic target to attenuate atrophy during unloading and to enhance rehabilitation upon reloading of skeletal muscles, due to its multipronged actions on satellite cell proliferation, differentiation, and survival, as well as its actions on muscle fibers to boost protein synthesis and inhibit protein degradation. However, the form of IGF-I delivered may alter the success of treatment.

Automated drug screening with contractile muscle tissue engineered from dystrophic myoblasts.

Identification of factors that improve muscle function in boys with Duchenne muscular dystrophy (DMD) could lead to an improved quality of life. To establish a functional in vitro assay for muscle strength, mdx murine myoblasts, the genetic homologue of DMD, were tissue engineered in 96-microwell plates into 3-dimensional muscle constructs with parallel arrays of striated muscle fibers. When electrically stimulated, they generated tetanic forces measured with an automated motion tracking system.