title: Long-term functional adeno-associated virus-microdystrophin expression in the dystrophic CXMDj dog.
abstract: BACKGROUND
  Duchenne muscular dystrophy (DMD) is a severe, inherited, muscle-wasting disorder caused by mutations in the dystrophin gene. Preclinical studies of adeno-associated virus gene therapy for DMD have been described in mouse and dog models of this disease. However, low and transient expression of microdystrophin in dystrophic dogs and a lack of long-term microdystrophin expression associated with a CD8(+)  T-cell response in DMD patients suggests that the development of improved microdystrophin genes and delivery strategies is essential for successful clinical trials in DMD patients.
  
  
  METHODS
  We have previously shown the efficiency of mRNA sequence optimization of mouse microdystrophin in ameliorating the pathology of dystrophic mdx mice. In the present study, we generated adeno-associated virus (AAV)2/8 vectors expressing an mRNA sequence-optimized canine microdystrophin under the control of a muscle-specific promoter and injected intramuscularly into a single canine X-linked muscular dystrophy (CXMDj) dog.
  
  
  RESULTS
  Expression of stable and high levels of microdystrophin was observed along with an association of the dystrophin-associated protein complex in intramuscularly injected muscles of a CXMDj dog for at least 8 weeks without immune responses. Treated muscles were highly protected from dystrophic damage, with reduced levels of myofiber permeability and central nucleation.
  
  
  CONCLUSIONS
  The data obtained in the present study suggest that the use of canine-specific and mRNA sequence-optimized microdystrophin genes in conjunction with a muscle-specific promoter results in high and stable levels of microdystrophin expression in a canine model of DMD. This approach will potentially allow the reduction of dosage and contribute towards the development of a safe and effective AAV gene therapy clinical trial protocol for DMD.
authors.affiliation: SWAN Institute of Biomedical and Life Sciences, School of Biological Sciences, Royal Holloway University of London, Egham, Surrey, UK.
authors.forename: Taeyoung
authors.initials: T
authors.lastname: Koo
authors.forename: Takashi
authors.initials: T
authors.lastname: Okada
authors.forename: Takis
authors.initials: T
authors.lastname: Athanasopoulos
authors.forename: Helen
authors.initials: H
authors.lastname: Foster
authors.forename: Shin'ichi
authors.initials: S
authors.lastname: Takeda
authors.forename: George
authors.initials: G
authors.lastname: Dickson
mesh_terms: D000818:Animals; D017931:DNA Primers / Q000235:genetics; D000229:Dependovirus / Q000235:genetics*; D004285:Dogs; D016189:Dystrophin / Q000235:genetics / Q000378:metabolism*; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000008:administration & dosage; D006652:Histological Techniques; D007273:Injections, Intramuscular; D018482:Muscle, Skeletal / Q000378:metabolism / Q000473:pathology; D020388:Muscular Dystrophy, Duchenne / Q000235:genetics* / Q000378:metabolism / Q000628:therapy*; D012333:RNA, Messenger / Q000378:metabolism*
chemical_list: D017931:DNA Primers; D016189:Dystrophin; D012333:RNA, Messenger