Figure 3

Muscle regeneration of progeroid Zmpste24^-/- muscle-derived stem/progenitor cells (MDSPCs) is impaired in vivo. To measure MDSPC function in vivo, WT and Zmpste24^-/- MDSPCs were injected into the gastrocnemius muscle of 8-week-old mdx/SCID mice. (A) Representative images of sections of gastrocnemius muscle from dystrophic mice 14 days after injection immunostained for dystrophin (red) to identify regenerated myofibers. Scale bar, 100 μm; inset, 50 μm. (B) Quantification of the cross-sectional area of > 1,500 dystrophin-positive myofibers per group. The distribution of fiber size is indicated on the x-axis, representing increasingly more mature fibers with increased size (*P < 0.001; Mann-Whitney Rank Sum test at each size range except 100 to 200). Graph represents the results from injection of three to four mdx/SCID mice with three independent MDSPC populations per group.