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THE ROLE OF STEM CELL ANTIGEN-1(Sca-1) IN MUSCLE AGING

Muscle aging is associated with a decrease in the number of satellite cells and their progeny, muscle progenitor cells (MPCs) that are available for muscle repair and regeneration. However, there is an increase in non-immuno-hematopoietic cells (CD45 negative) in regenerating muscle from aged mice characterized by high stem cell antigen -1(Sca-1) expression. In aged regenerating muscle, 14.2% of cells are CD45neg Sca-1pos while 7.2% of cells are CD45neg Sca-1pos in young adult muscle. In vitro, CD45neg Sca-1pos cells over express genes associated with fibrosis, potentially controlled by Wnt2. These cells are proliferative, non-myogenic and non-adipogenic, and arise in clonally-derived MPCs cultures from aged mice. Both in vitro and in vivo studies suggest that CD45neg Sca-1pos cells from aged muscle are more susceptible to apoptosis than their MPCs, which may contribute to depletion of the satellite cell pool. Therefore, with age, a subset of MPCs takes on an altered phenotype, which is marked by high Sca-1 expression. This altered phenotype prevents these cells from participating in muscle regeneration or replenishing the satellite cell pool, and instead may contribute to fibrosis in aged muscle.

Identiferoai:union.ndltd.org:uky.edu/oai:uknowledge.uky.edu:gradschool_theses-1523
Date01 January 2008
CreatorsRichards-Malcolm, Sonia Angela
PublisherUKnowledge
Source SetsUniversity of Kentucky
Detected LanguageEnglish
Typetext
Formatapplication/pdf
SourceUniversity of Kentucky Master's Theses

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