Human satellite cells (SC) are small mononuclear stem cells, quiescent in undamaged skeletal muscle, but in response to muscle damage are activated to proliferate as skeletal myoblasts and to fuse in myotubes⁽¹⁾. During the ageing process SC display a reduced capability to undergo the differentiation process, probably due to increase of oxidative damage and decrease of scavenger activity⁽²⁾. This evidence was confirmed with microarrays analysis showing an age-related altered expression of some genes involved in antioxidant and repair activity (Polimerase K, SHC1 and FOXO1A)⁽³⁾. We hypothesized that apoptosis may be one of the possible mechanism responsible for the impaired differentiation ability of these SC in the elderly population. Cells were obtained from Vastus Lateralis of 9 young (27.3+2.0 years old) and 9 old (71.1±1.8 years old) subjects and cultured in complete or serum-free medium to be collected at 4-24-48 and 72 h. Apoptosis was assessed with Annexin V/PI staining revealing a time-dependent and significantly higher percentage of apoptotic SC from elderly. Further RT-PCR analysis performed using TaqMan Low Density Array demonstrated an alteration of differentiation and apoptotic processes. These results suggest that ageing impairs the SC response to differentiation due to also increased susceptibility to apoptosis.

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