Résumé :
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Communication n° 149. The goal of our study was to isolate homogenous murine cell population enriched in muscle stem cells and to determine the phenotype and the transcriptional signature of these cells. We developed primary culture of muscle cells from adult mice, which allows a novel approach to obtain an homogenous source of muscular cells. The myogenic purity of this primary culture showed on average 90-95% of desmin-positive cells. Isolation of stem like-enriched SP and differentiated MP cell populations was performed on adherent cells by Hoechst 33342 staining followed by FACS. Phenotypic characterization of SP cells was performed by immunostaining and showed that SP cells were negative for the pan-leukocyte marker CD45, the endothelial cell/hematopoietic progenitor markers CD34 and CD38 and the endothelial cell marker CD31 and 99% positive for the HSC antigen Sca1. Transcriptomes of the SP and MP cell populations derived from primary culture of myoblasts were characterized using a DNA chip containing 11 000 murine genes. Analysis of the expression profiles showed that about 2 % of the genes were either up-regulated or down-regulated in SP compared to MP cells. The distribution of these genes, accordingly to their cellular functions, showed an involvement in the maintenance of genome integrity, the regulation of transcription and RNA processing and the inhibition of cell proliferation for the up-regulated genes in SP cells and in protein synthesis, metabolism, cellular morphogenesis and cell differentiation for the down-regulated genes. Furthermore, some potential markers of stem cells have been identified. In addition, the comparison of muscle and hematopoietic SP transcriptomes lead to the observation that a subset of genes shared a common expression profile in both SP populations. In conclusion, the outcome of our project provides novel insights into the spectrum of genes that specifies the identity and the phenotype of population enriched in muscle stem cells.
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