RESUMO
Duchenne muscular dystrophy (DMD) is characterized in skeletal muscle by cycles of myofiber necrosis and regeneration leading to loss of muscle fibers and replacement with fibrotic connective and adipose tissue. The ongoing activation and recruitment of muscle satellite cells for myofiber regeneration results in loss of regenerative capacity in part due to proliferative senescence. We explored a method whereby new myoblasts could be generated in dystrophic muscles by transplantation of primary fibroblasts engineered to express a micro-dystrophin/enhanced green fluorescent protein (muDys/eGFP) fusion gene together with a tamoxifen-inducible form of the myogenic regulator MyoD [MyoD-ER(T)]. Fibroblasts isolated from mdx(4cv) mice, a mouse model for DMD, were efficiently transduced with lentiviral vectors expressing muDys/eGFP and MyoD-ER(T) and underwent myogenic conversion when exposed to tamoxifen. These cells could also be induced to differentiate into muDys/eGFP-expressing myocytes and myotubes. Transplantation of transduced mdx(4cv) fibroblasts into mdx(4cv) muscles enabled tamoxifen-dependent regeneration of myofibers that express muDys. This lineage control method therefore allows replenishment of myogenic stem cells using autologous fibroblasts carrying an exogenous dystrophin gene. This strategy carries several potential advantages over conventional myoblast transplantation methods including: (i) the relative simplicity of culturing fibroblasts compared with myoblasts, (ii) a readily available cell source and ease of expansion and (iii) the ability to induce MyoD gene expression in vivo via administration of a medication. Our study provides a proof of concept for a novel gene/stem cell therapy technique and opens another potential therapeutic approach for degenerative muscle disorders.
Assuntos
Linhagem da Célula , Distrofina/genética , Terapia Genética/métodos , Desenvolvimento Muscular , Distrofias Musculares/genética , Distrofias Musculares/terapia , Animais , Diferenciação Celular , Linhagem Celular , Distrofina/metabolismo , Fibroblastos/fisiologia , Fibroblastos/transplante , Vetores Genéticos/genética , Proteínas de Fluorescência Verde/genética , Proteínas de Fluorescência Verde/metabolismo , Humanos , Lentivirus/genética , Camundongos , Camundongos Endogâmicos C57BL , Distrofia Muscular Animal/genética , Distrofia Muscular Animal/terapia , Proteína MyoD/genética , Proteína MyoD/metabolismo , Mioblastos/fisiologia , Células NIH 3T3 , Receptores de Estrogênio/genética , Receptores de Estrogênio/metabolismo , Proteínas Recombinantes de Fusão/genética , Proteínas Recombinantes de Fusão/metabolismoRESUMO
Mice carrying mutations in both the dystrophin and utrophin genes die prematurely as a consequence of severe muscular dystrophy. Here, we show that intravascular administration of recombinant adeno-associated viral (rAAV) vectors carrying a microdystrophin gene restores expression of dystrophin in the respiratory, cardiac and limb musculature of these mice, considerably reducing skeletal muscle pathology and extending lifespan. These findings suggest rAAV vector-mediated systemic gene transfer may be useful for treatment of serious neuromuscular disorders such as Duchenne muscular dystrophy.
