DMD and Duchenne muscular dystrophy: To investigate the myogenic potential of progeroid Zmpste24-/- MDSPCs in vivo, 3 × 105 viable MDSPCs isolated from WT and Zmpste24-/- mice were injected into the gastrocnemius muscle of 8-week-old mdx/SCID mice, a mouse model of Duchenne muscular dystrophy that lacks dystrophin at the sarcolemma of muscle fibers [33] and is also immunoincompetent.