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In Duchenne muscular dystrophy (DMD) patients, absence of dystrophin causes muscle wasting by impacting both the myofiber integrity and the properties of muscle stem cells (MuSCs). Investigation of DMD encompasses the use of MuSCs issued from human skeletal muscle. However, DMD-derived MuSC usage is restricted by the limited number of divisions that human MuSCs can undertake in vitro before losing their myogenic characteristics and by the scarcity of human material available from DMD muscle. To overcome these limitations, immortalization of MuSCs appears as a strategy. Here, we used CDK4/hTERT expression in primary MuSCs and we derived MuSC clones from a series of clinically and genetically characterized patients, including eight DMD patients with various mutations, four congenital muscular dystrophies and three age-matched control muscles. Immortalized cultures were sorted into single cells and expanded as clones into homogeneous populations. Myogenic characteristics and differentiation potential were tested for each clone. Finally, we screened various promoters to identify the preferred gene regulatory unit that should be used to ensure stable expression in the human MuSC clones. The 38 clonal immortalized myogenic cell clones provide a large collection of controls and DMD clones with various genetic defects and are available to the academic community.

Objectives: Muscle pain is a frequent concomitant symptom in a variety of neuromuscular disease and the most prominent findings in myofascial pain syndrome, as well as in fibromyalgia syndrome. Findings: Negligible awareness has been focused on pain characteristics in neuromuscular disorders. In the group of inflammatory myopathies, in dermatomyositis, the highest frequency of permanent muscle pain is complained in the shoulder girdle and thigh, and upper anus and legs. Pain quality is reported to be muscle-aching in the majority of patients, but additional different pain characteristics have been documented, including deep, gripping, dull, bright, sharp and superficial. Here small free nerve endings are connected to small blood vessels that show an upregulation of substance P and calcitonine gene related peptide as signs of an increased nociceptive input. Some forms of metabolic myopathies, especially glycogenolytic defects, are characterized by symptoms of stamina, painful contractures with exercise, cramps, and myoglobinuna. Pain expression in McArdle patients with chronic myalgia has frequently the features of functional muscle pain, or fibromyalgia syndrome. Depletion of high-energy phosphates like phosphocreatine and adenosine triphosphate during exercise may contribute to the pathogenesis. In degenerative myopathies, only a few disorders are investigated for pain pattern, but affected patients clearly present with muscle pain in myotonic dystrophies, facioscapulohumeral muscular dystrophy, other rare degenerative myopathies, and the peculiar rippling muscle disease. Most prevalent but still underrecognized as cause of muscle pain is the myofascial pain syndrome. Conclusion: The pathogenetic background of many type of muscle pain is still uncertain. Free nerve endings, substance P and adenosine triphosphate and tissue acidosis seem to be the player in muscle pain. [ABSTRACT FROM AUTHOR]

In Duchenne muscular dystrophy (DMD) patients, absence of dystrophin causes muscle wasting by impacting both the myofiber integrity and the properties of muscle stem cells (MuSCs). Investigation of DMD encompasses the use of MuSCs issued from human skeletal muscle. However, DMD-derived MuSC usage is restricted by the limited number of divisions that human MuSCs can undertake in vitro before losing their myogenic characteristics and by the scarcity of human material available from DMD muscle. To overcome these limitations, immortalization of MuSCs appears as a strategy. Here, we used CDK4/hTERT expression in primary MuSCs and we derived MuSC clones from a series of clinically and genetically characterized patients, including eight DMD patients with various mutations, four congenital muscular dystrophies and three age-matched control muscles. Immortalized cultures were sorted into single cells and expanded as clones into homogeneous populations. Myogenic characteristics and differentiation potential were tested for each clone. Finally, we screened various promoters to identify the preferred gene regulatory unit that should be used to ensure stable expression in the human MuSC clones. The 38 clonal immortalized myogenic cell clones provide a large collection of controls and DMD clones with various genetic defects and are available to the academic community. [ABSTRACT FROM AUTHOR]