title: Adeno-associated virus-mediated microdystrophin expression protects young mdx muscle from contraction-induced injury.
abstract: Duchenne muscular dystrophy (DMD) is the most common inherited lethal muscle degenerative disease. Currently there is no cure. Highly abbreviated microdystrophin cDNAs were developed recently for adeno-associated virus (AAV)-mediated DMD gene therapy. Among these, a C-terminal-truncated DeltaR4-R23/DeltaC microgene (DeltaR4/DeltaC) has been considered as a very promising therapeutic candidate gene. In this study, we packaged a CMV.DeltaR4/DeltaC cassette in AAV-5 and evaluated the transduction and muscle contractile profiles in the extensor digitorum longus muscles of young (7-week-old) and adult (9-month-old) mdx mice. At approximately 3 months post-gene transfer, 50-60% of the total myofibers were transduced in young mdx muscle and the percentage of centrally nucleated myofibers was reduced from approximately 70% in untreated mdx muscle to approximately 22% in microdystrophin-treated muscle. Importantly, this level of transduction protected mdx muscle from eccentric contraction-induced damage. In contrast, adult mdx muscle was more resistant to AAV-5 transduction, as only approximately 30% of the myofibers were transduced at 3 months postinfection. This transduction yielded marginal protection against eccentric contraction-induced injury. The extent of central nucleation was also more difficult to reverse in adult mdx muscle (from approximately 83% in untreated to approximately 58% in treated). Finally, we determined that the DeltaR4/DeltaC microdystrophin did not significantly alter the expression pattern of the endogenous full-length dystrophin in normal muscle. Neither did it have any adverse effects on normal muscle morphology or contractility. Taken together, our results suggest that AAV-mediated DeltaR4/DeltaC microdystrophin expression represents a promising approach to rescue muscular dystrophy in young mdx skeletal muscle.
authors.affiliation: Department of Molecular Microbiology and Immunology, University of Missouri School of Medicine, One Hospital Drive, Room M610G, MSB, Columbia, MO 65212, USA.
authors.forename: Mingju
authors.initials: M
authors.lastname: Liu
authors.forename: Yongping
authors.initials: Y
authors.lastname: Yue
authors.forename: Scott Q
authors.initials: SQ
authors.lastname: Harper
authors.forename: Robert W
authors.initials: RW
authors.lastname: Grange
authors.forename: Jeffrey S
authors.initials: JS
authors.lastname: Chamberlain
authors.forename: Dongsheng
authors.initials: D
authors.lastname: Duan
mesh_terms: D000375:Aging / Q000502:physiology*; D000818:Animals; D002460:Cell Line; D000229:Dependovirus / Q000235:genetics*; D016189:Dystrophin / Q000235:genetics / Q000378:metabolism*; D015870:Gene Expression; D006801:Humans; D051379:Mice; D018101:Mice, Inbred mdx; D009119:Muscle Contraction / Q000502:physiology; D018482:Muscle, Skeletal / Q000293:injuries* / Q000378:metabolism* / Q000502:physiology / Q000503:physiopathology
chemical_list: D016189:Dystrophin