Satellite cells

Differentiated fibres are not capable of proliferation, but a small population of myoblasts (satellite cells) persists in mature muscle. They can be stimulated to proliferate and fuse with existing fibres to increase the number of nuclei present and restore the critical ratio of nuclei to cytoplasm that has been reduced by fibre enlargement. 

Provided that blood supply and innervation remain intact, skeletal muscle heals well after injury or disease. Damage to fibres causes endothelial cells to secrete general growth factors (e.g. fibroblast growth factor, insulin-like growth factors) and growth factors specific to muscle development which stimulate proliferation of satellite cells. These then migrate to the site of injury to form myotubes, as in foetal development. If, however, the number of satellite cells is... 

The number of satellite cells in skeletal muscle declines with age so that recovery after injury is slower in the elderly. Moreover, no satellite cells are present in cardiac muscle, and damage (e.g. after a heart attack) is not repaired but is replaced by scar tissue. These are no reports of severe muscle damage in top sports personalities berg treated with embryonic stem cells. Rapid recovery from such damage, may be financially rewarding to both the athlete and the club, so that such treatment may be considered in the future. 

Skeletal myoblasts are adult, tissue-specific stem cells [73] located between the basal lamina and the sarcolemma on the periphery of the mature skeletal-muscle fiber [74]. Also known as muscle satellite cells, these small, mononuclear cells are activated by biochemical signals to divide and differentiate into fusion-competent cells after muscle injury. 

One possible mechanism responsible for the ability of trenbolone acetate to stimulate skeletal muscle hypertrophy may be through enhanced proliferation and differentiation of satellite cells as the result of increased sensitivity to insulin-like growth factor-I (IGF-1) and fibroblast growth factor (43). 

Satellite-cell production and subsequent fiber inclusion are predominantly stimulated by IGF-1 and FGF (See IGF-1 and FGF for more info). 

How many times have you heard some gym supplement expert say that the weight gained from creatine is just water Well, researchers wrote an interesting paper concerning creatine called Dangott, B. Schulz, E. Mozdziak, P.E. "Dietary Creatine Monohydrate supplementation increases satellite cell mitotic activity during compensatory hypertrophy" in International Journal of Sports Medicine 21 13-16,2000. What the heck is that, huh ... 

Chiu RC, Zibaitis A, Kao RL. Cellular cardiomyoplasty myocardial regeneration with satellite cell implantation. Ann Thorac Surg 1995 60 12-18. 

Horackova M, Arora R, Chen R, et al. Cell transplantation for treatment of acute myocardial infarction unique capacity for repair by skeletal muscle satellite cells. Am J Physiol Heart Circ Physiol 2004 287 H I 599-H I 608. 

Skeletal muscle cells are capable of regeneration and repair more readily than cardiac myocytes owing to the so-called satellite cells that can be readily mobilized at the time of injury (16). They are capable of easy expansion in culture can be harvested easily from the autologous host and are fairly resistant to hypoxia (17). The major drawback is that as the skeletal myocytes mature, they no longer form gap junctions and become electrically isolated, predisposing to re-entry arrhythmias (18). In addition, despite some encouraging data (19), the viability of dissociated myoblasts in suspension injected into myocardial scar deprived of appropriate trophic environment has been called into question (20), In our hands, skeletal myoblasts injected into canine myocardium could not be identified four weeks after implantation, and the needle tract caused fibrosis and scarring (Fig. 2). 

Mauro A. Satellite cell of skeletal muscle fibers. J Biophys Biochem Cytol 1961 9 493-495. 

Skeletal muscle responds to injury by the activation of a regeneration process (Bischoff, 1979). As described in more detail below, muscle regeneration is a repeated embryonic development of the skeletal muscle only that in this case it starts from the dormant mononucleated satellite cells located between the basal lamina and cell membrane of the adult skeletal muscle fiber. The final outcome after the muscle damage therefore depends not only on the extent of the damage itself but also on the efficiency of the... 

All stages of muscle regeneration can be reproduced in the experimental model of the in vitro innervated human muscle (Figure 45.IB). This system was first described in the 1980s (Kobayashi and Askanas, 1985 Askanas et al, 1987) and then further characterized in studies in various laboratories, including ours. In this experimental model satellite cells are released by trypsinization from small pieces of adult human muscle routinely removed at the orthopedic operations of the equinovarus. These cells are the source of mononucleated myoblasts which then proliferate and at certain density start to fuse and form multinucleated myotubes. At that stage an explant of the rat embryonic spinal cord is placed on a monolayer of muscle... 

Cantini, M., Massimino, M.L., Rapizzi, E., Rossini, K., Catani, C., Dalla Libera, L., Carraro, U. (1995). Human satellite cell proliferation in vitro is regulated by autocrine secretion of IL-6 stimulated by a soluble factor(s) released by activated monocytes. Biochem. Biophys. Res. Commun. 216 49-53. 

Serrano, A.L., Baeza-Raja, B., Perdiguero, E., Jardi, M., Munoz-Canoves, P. (2008). Interleukin-6 is an essential regulator of satellite cell-mediated skeletal muscle hypertrophy. Cell Metab. 7 33-44. 

Na-b/K-l-ATPaseBl subunit Plasma membrane Subtype specific antibody labeling Neurons, satellite cells in R. norvegicus Yes (Schirmer et al. 2003 Arteaga et al. 2004)... 

Intermingled with the neurons in the brain are a variety of other cell types. The most common of these satellite cells are glial cells. These make up virtually about one half of the total volume of the brain and exist in several forms such as astrocytes, oligodendrocytes, and Schwann cells. Membrane properties of glial cells exhibit fundamental differences from neurons, the chief difference being their passive nature. Unlike neurons, most glial cells are not excitable and do not fire action potentials. Membrane potential measurements of... 

Okay, some people might consider it an exaggeration to call a photocopy machine a miracle, but for anyone who has dealt with mimeograph machines, miracle is almost too weak. Photocopy machines are nearly as integral to the information age as computers and satellite cell phones. For all... 

After 12-14 hours of exposure of rats to a relatively small amount of metallic mercury vapor (0.55 mg/m3), accumulation of mercury was observed within all cell types examined (ganglion cells, satellite cells, fibroblasts, and macrophages). Mercury has also been detected in dorsal root neurons and satellite cells of primates exposed for one year to mercury through amalgams in dental fillings or the maxillary bone (Danscher et al. 1990). 

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