Human Molecular Genetics Advance Access originally published online on May 29, 2008
Human Molecular Genetics 2008 17(16):2507-2517; doi:10.1093/hmg/ddn151
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Cell-lineage regulated myogenesis for dystrophin replacement: a novel therapeutic approach for treatment of muscular dystrophy
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,1 Department of Neurology, Senator Paul D Wellstone Muscular Dystrophy Cooperative Research Center 2 Department of Biochemistry 3 Department of Medicine, University of Washington School of Medicine, Seattle, WA 98195-7720, USA 4 Division of Human Biology, Fred Hutchinson Cancer Research Center, Seattle, WA 98109-1024, USA
* To whom correspondence should be addressed. Tel: +1 2066166645; Fax: +1 2066168272; Email: jsc5{at}u.washington.edu
Received May 8, 2008; Accepted May 13, 2008
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 (µDys/eGFP) fusion gene together with a tamoxifen-inducible form of the myogenic regulator MyoD [MyoD-ER(T)]. Fibroblasts isolated from mdx4cv mice, a mouse model for DMD, were efficiently transduced with lentiviral vectors expressing µDys/eGFP and MyoD-ER(T) and underwent myogenic conversion when exposed to tamoxifen. These cells could also be induced to differentiate into µDys/eGFP-expressing myocytes and myotubes. Transplantation of transduced mdx4cv fibroblasts into mdx4cv muscles enabled tamoxifen-dependent regeneration of myofibers that express µDys. 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.
Present address: Department of Neurology, Kumamoto University Graduate School of Medical Sciences, Kumamoto, Japan.
Present address: Department of Physical Medicine and Rehabilitation, Universiy of California, Davis, CA, USA.
The authors wish it to be known that, in their opinion, the first two authors should be regarded as joint First Authors.