Intraarterial injection of muscle-derived CD34(+)Sca-1(+) stem cells restores dystrophin in mdx mice

Duchenne muscular dystrophy is a lethal recessive disease characterized by widespread muscle damage throughout the body. This increases the difficulty of cell or gene therapy based on direct injections into muscles. One way t o circumvent this obstacle would be to use circulating cells capable of hom ing to the sites of lesions. Here, we showed that stem cell antigen 1 (Sca- 1), CD34 double-positive cells purified from the muscle tissues of newborn mice are multipotent in vitro and can undergo both myogenic and multimyeloi d differentiation. These muscle-derived stem cells were isolated from newbo rn mice expressing the LacZ gene under the control of the muscle-specific d esmin or troponin I promoter and injected into arterial circulation of the hindlimb of mdx mice. The ability of these cells to interact and firmly adh ere to endothelium in mds muscles microcirculation was demonstrated by intr avital microscopy after an intraarterial injection. Donor Sca-1, CD34 muscl e-derived stem cells were able to migrate from the circulation into host mu scle tissues. Histochemical analysis showed colocalization of LacZ and dyst rophin expression in all muscles of the injected hindlimb in all of five ou t of five 8-wk-old treated mdx mice. Their participation in the formation o f muscle fibers was significantly increased by muscle damage done 48 h afte r their intraarterial injection, as indicated by the presence of 12% beta - galactosidase-positive fibers in muscle cross sections. Normal dystrophin t ranscripts detected enzymes in the muscles of the hind limb injected intraa rterially by the mdx reverse transcription polymerase chain reaction method , which differentiates between normal and mdx message. Our results showed t hat the muscle-derived stem cells first attach to the capillaries of the mu scles and then participate in regeneration after muscle damage.