Figure 1

CD15 and PDGFRα are specific markers of human FAPs. (a) Representative results from flow cytometry analysis of adherent human muscle cells. The CD56 negative cells (left upper panel) were labeled with both anti-CD15 and anti-PDGFRα (CD140a; right upper panel). The lower panels represent the respective isotype negative labelings. Percentages of the fractions are indicated. (b) Kinetic expression of PDGFRα and CD15 shown for a representative muscle biopsy (FAP biopsy 7). PDGFRα expression was measured by quantitative RT-PCR and CD15 expression was measured by flow cytometry. At day D0, the cells were confluent and proliferation medium was replaced by differentiation medium. Measurements were done every 2 days until day D8. (c) After confluence (D0), cells were put under differentiation conditions. Myotubes were labeled with antimyosin heavy-chain antibodies and muscle creatine kinase (MCK) expression was compared with quantitative RT-PCR between days D0 and D5. Adipocytes were stained with oil red O and FABP4 expression was compared with quantitative RT-PCR between days D0 and D11. Fibroblast-like cells were labeled with anti-α smooth muscle actin and its expression was compared with quantitative RT-PCR between days D0 and D5. Quantitative RT-PCR results are mean±S.E. of the mean (n=3; FAP biopsies 2, 9, and 10). **P<0.01. FITC, fluorescein isothiocyanate; PE, phycoerythrin; SSC, side scatter detector