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Satellite cells are myogenic stem cells responsible for the postnatal regeneration of skeletal muscle. Here we report the successful in vitro induction of Pax7-positive satellite-like cells from mouse embryonic stem (mES) cells. Embryoid bodies were generated from mES cells and cultured on Matrigel-coated dishes with Dulbecco's modified Eagle medium containing fetal bovine serum and horse serum. Pax7o-positive satellite-like cells were enriched by fluorescence-activated cell sorting using a novel anti-satellite cell antibody, SM/C-2.6. SM/C-2.6-positive cells efficiently differentiate into skeletal muscle fibers both in vitro and in vivo. Furthermore, the cells demonstrate satellite cell characteristics such as extensive self-renewal capacity in subsequent muscle injury model, long-term engraftment up to 24 wk, and the ability to be secondarily transplanted with remarkably high engraftment efficiency compared to myoblast transplantation. This is the first report of transplantable, functional satellite-like cells derived from mES cells and will provide a foundation for new therapies for degenerative muscle disorders. [ABSTRACT FROM AUTHOR]

Prolonged inactivity is known to induce the responses of physiological defense systems such as the hypothalamo-hypophyseal-adrenocortical axis, sympathetic nervous system, and immuno-responsive systems. However, the effects of different types of inactivity on immuno-responsive systems are still unknown. Therefore, the effects of two types of inactivity (immobilization: IMM and whole body suspension: WBS) on the number of white blood cells were studied in rats. Male adult rats were divided into the control and each inactivity groups to compare the number of total white blood cells, lymphocytes, monocyte, neutrophil, eosinophil, and basophil. Both IMM and WBS were maintained for 11 days. IMM markedly increased the number of total white blood cells, monocyte, neutrophil, and eosinophil in the 1st-10th day, whereas WBS-induced changes of the number of these cells were characterized by the presence of a lag phase followed by the significant increased actions. IMM did not change the number of basophil. However, WBS increased the number of basophil in the 1st-8th day to 2.8-4.8 times, compared with the values of the control. Both IMM and WBS did not change the number of lymphocytes. These results show that WBS increase the number of natural immunity cells without changing acquired immunity cells, and there are different responses in the number of total white blood cells and natural immunity cells between IMM and WBS. [ABSTRACT FROM AUTHOR]

Clenbuterol (CLE: 4-amino-α(t-butyl-amino)methyl-3,5-diehlorobenzyl alcohol) is well known as the potent β2-adrenergic agonist and nonsteroidal anabolic drug, thus generally used for the sports doping and asthma therapy. However, the administration effects of CLE on immune-responsive systems have not been elucidated. Therefore, the administration effects of CLE on the number of white blood cells were studied in rats. Male adult rats were divided into the control and CLE-administered groups to compare the number of total white blood cells, neutrophil, monocyte, lymphocytes, eosinophil, and basophil. The administration (dose = 1.0 mg · kg-1 body weight · day-1) of CLE was maintained for 30 days. The administration of CLE did not change the number of total white blood cells during the experimental period. However, the administration of CLE decreased drastically the number of lymphoeytes and eosinophil, while increased significantly the number of monocyte and neutrophil during the experimental period. There was no significant change in the number of basophil during the experimental period. These results suggest that the administration of CLE induces drastic redistribution of circulating white blood cells without changing the number of total white blood cells, and these redistribution responses of circulating white blood cells during the administration of CLE are sustained for at least 30 days. [ABSTRACT FROM AUTHOR]