Dystrophin expression in host muscle following transplantation of muscle precursor cells modified with the phiC31 integrase

Duchenne muscular dystrophy (DMD) is the most severe muscular dystrophy. It is caused by the absence of dystrophin in muscle fibers. The autologous transplantation of genetically corrected muscle precursor cells (MPCs) is a possible cure for DMD. A non-viral method of genetic modification was tested in this study. The co-transfection (nucleofection) of a phiC31 integrase and a transgene expressing plasmid in MPCs led to an increased stable expression in vitro. The stable expression of a small transgene (eGFP) in muscle fibers was initially demonstrated following the transplantation of the genetically modified cells. The stable expression of a truncated version of dystrophin as well as the full-length dystrophin fused with eGFP was then demonstrated in MPCs obtained from an mdx mice. The transplantation of these cells led not only to the expression of these fusion proteins in muscle fibers but also to the reconstitution of the dystrophin complex. Human MPCs were also genetically modified with a plasmid coding for the full-length human dystrophin gene fused with eGFP and transplanted in severe combined immuno deficient mice leading to the expression of eGFP dystrophin in muscle fibers. This work indicates that cell transplantation after correction of MPCs with phiC31 integrase is a possible approach to treat DMD.