Figure 5. Atm heterozygosity improves muscle stem cell function and muscle regeneration. Myogenic progenitor cells (myoblasts) and MDSPCs were isolated via preplate technique, 3 days after myoblasts were obtained, and the bright field pictures were taken. A total of three populations of Atm+/-, Ercc1-/∆Atm+/- and Ercc1-/∆ were isolated from distinct mice and tested. All scale bars = 100 μm. (A) MDSPCs were cultured in myogenic differentiation medium for 3 days. Bright field images were taken and the cell fusion into multinucleated myotubes was determined by immuno-staining for MyHCf, a terminal myogenic differentiation marker. (B) Cell proliferation of MDSPCs was measured using an MTS assay. The graph displays the average of three populations. Error bars indicate mean ± SD. ***P<0.001 (C) Representative images of immunofluorescence detection of differentiated myofibers. All scale bars in panel C=50 μm. (D) Myogenic differentiation was quantified by determining the number of nuclei in MyHCf positive myotubes relative to the total number of nuclei in the culture. Error bars indicate “mean ±SD”. *P<0.05. **P<0.01. Error bars indicate “mean ± SD”. *P<0.05. Two-tailed Student’s t-test was performed.