Rescue of dystrophic muscle after intramuscular and intra-arterial transplantation of AC133⁺ cells derived from blood. (A) The scid/mdx muscles showed classic signs of muscular dystrophy. (B and C) The muscles of scid/mdx animals showed a considerable decrease in necrosis and central nucleated myofibers 21 (B) and 45 (C) days after intramuscular transplantation. (D) After 60 days, the myofibers generated by intramuscular transplantation of blood-derived AC133⁺ cells were larger in both CSA and diameter, with peripheral nuclei. (E and F) Higher magnification of the inset in B and D is shown in E and F. Morphometric analysis of H&E–stained muscle sections from injected and uninjected scid/mdx mice during aging was also performed (G). The number of human dystrophin–positive myofibers 60 days after intramuscular transplantation (I) was higher than in muscle injected 21 days before analysis (H). (J) Staining with anti–human dystrophin (red) confirmed that several Dys3⁺ myofibers expressed the anti–human nuclear lamin A/C antigen (green; arrows) 21 days after intramuscular transplantation of cloned AC133⁺-derived cells (J). Human Dys3⁺ myofibers (purple) with human lamin A/C nuclei (green) were present in dystrophic muscles after intra-arterial transplantation of the AC133⁺ cells (K). Higher magnification of the inset in K is shown in L (arrowheads indicate the human lamin A/C–positive nuclei within Dys3⁺ myofibers) and M with DAPI (blue) and PKH26 (red). Human Dys3⁺ myofibers (N) were detected near mononucleated human lamin A/C–positive cells after intra-arterial delivery (O). A merge of N and O is shown in P.