title: The depletion of skeletal muscle satellite cells with age is concomitant with reduced capacity of single progenitors to produce reserve progeny.
abstract: Satellite cells are myogenic progenitors that reside on the myofiber surface and support skeletal muscle repair. We used mice in which satellite cells were detected by GFP expression driven by nestin gene regulatory elements to define age-related changes in both numbers of satellite cells that occupy hindlimb myofibers and their individual performance. We demonstrate a reduction in satellite cells per myofiber with age that is more prominent in females compared to males. Satellite cell loss also persists with age in myostatin-null mice regardless of increased muscle mass. Immunofluorescent analysis of isolated myofibers from nestin-GFP/Myf5(nLacZ/+) mice reveals a decline with age in the number of satellite cells that express detectable levels of betagal. Nestin-GFP expression typically diminishes in primary cultures of satellite cells as myogenic progeny proliferate and differentiate, but GFP subsequently reappears in the Pax7(+) reserve population. Clonal analysis of sorted GFP(+) satellite cells from hindlimb muscles shows heterogeneity in the extent of cell density and myotube formation among colonies. Reserve cells emerge primarily within high-density colonies, and the number of clones that produce reserve cells is reduced with age. Thus, satellite cell depletion with age could be attributed to a reduced capacity to generate a reserve population.
authors.affiliation: Department of Biological Structure, Box 357420, Warren B Magneson Health Sciences Building, 1959 NE Pacific Street, University of Washington School of Medicine, Seattle, WA 98195, USA.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Day
authors.forename: Gabi
authors.initials: G
authors.lastname: Shefer
authors.forename: Andrew
authors.initials: A
authors.lastname: Shearer
authors.forename: Zipora
authors.initials: Z
authors.lastname: Yablonka-Reuveni
mesh_terms: D000375:Aging; D000818:Animals; D002469:Cell Separation; D002478:Cells, Cultured; D002999:Clone Cells; D015331:Cohort Studies; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D005456:Fluorescent Dyes / Q000378:metabolism; D049452:Green Fluorescent Proteins / Q000378:metabolism; D006579:Heterozygote; D007150:Immunohistochemistry; D007211:Indoles / Q000378:metabolism; D007381:Intermediate Filament Proteins / Q000378:metabolism; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008822:Mice, Transgenic; D018482:Muscle, Skeletal / Q000166:cytology / Q000378:metabolism; D009419:Nerve Tissue Proteins / Q000378:metabolism; D064231:Nestin; D051763:PAX7 Transcription Factor / Q000378:metabolism; D032496:Satellite Cells, Skeletal Muscle / Q000166:cytology* / Q000378:metabolism / Q000502:physiology*; D013234:Stem Cells / Q000166:cytology* / Q000502:physiology*; D019076:Transgenes / Q000235:genetics; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D005456:Fluorescent Dyes; D007211:Indoles; D007381:Intermediate Filament Proteins; D009419:Nerve Tissue Proteins; C577485:Nes protein, mouse; D064231:Nestin; D051763:PAX7 Transcription Factor; C497322:Pax7 protein, mouse; D049452:Green Fluorescent Proteins; C007293:DAPI; D001616:beta-Galactosidase