Figure 3.

MyoD and myogenin expression in chimeric mice and in vitro myogenic potential of CD34⁺/Sca-1⁻/CD45⁻ cells. Representative results were derived from injured skeletal muscle of chimeric mice at 7 days after CTX; BM donor and recipient strains are indicated as the BM donor strain → host mouse strain. MyoD-positive cells (red signal) (A–D) and myogenin-positive cells (red signal) (E–H) cells were more abundant in host mice receiving WT BM compared with mice receiving CCR2^−/− BM. Whereas MyoD- and myogenin-positive cells were present in areas containing BM-derived cells (green signal), the myogenic markers did not colocalize with the GFP signal. I, J) Myotube formation in cultured CD34⁺/Sca-1⁻/CD45⁻ cells isolated from hind limb muscle 3 days after CTX injection: phase contrast (I) and corresponding epifluorescent colocalization of MyoD (green) and myosin heavy chain (red) (J). All nuclei (identified with DAPI) were MyoD-positive. Myosin-negative mononucleated cell adjacent to myotube (arrowhead); myosin-positive mononucleated cell between mature myotubes (arrow).