Widespread muscle expression of an AAV9 human mini-dystrophin vector after intravenous injection in neonatal dystrophin-deficient dogs.
Duchenne (DMD) and golden retriever (GRMD) muscular dystrophy are caused by genetic mutations in the dystrophin gene and afflict striated muscles. We investigated systemic gene delivery in 4-day-old GRMD dogs given a single intravenous injection of an AAV9 vector (1.5 x 10(14) vector genomes/kg) carrying a human codon-optimized human mini-dystrophin gene under control of the cytomegalovirus (CMV) promoter. One of the three treated dogs was euthanized 9 days later due to pre-existing conditions. Scattered mini-dystrophin-positive myofibers were seen by immunofluorescent (IF) staining in numerous muscles. At the end of the 16-week study, the other two dogs showed generalized muscle expression of mini-dystrophin in ~15% to nearly 100% of myofibers. Western blot and vector DNA quantitative PCR results agreed with the IF data. Delayed growth and pelvic limb muscle atrophy and contractures were seen several weeks after vector delivery. T-2 weighted magnetic resonance imaging (MRI) at 8 weeks showed increased signal intensity compatible with inflammation in several pelvic limb muscles. This marked early inflammatory response raised concerns regarding methodology. Use of the ubiquitous CMV promoter, extra-high vector dose, and marked expression of a human protein in canine muscles may have contributed to the pathologic changes seen in the pelvic limbs.
Department of Pathology and Laboratory Medicine, University of North Carolina-Chapel Hill, Chapel Hill, NC 27599, USA. joe_kornegay@med.unc.edu
Joe N
JN
Kornegay
Juan
J
Li
Janet R
JR
Bogan
Daniel J
DJ
Bogan
Chunlian
C
Chen
Hui
H
Zheng
Bing
B
Wang
Chunping
C
Qiao
James F
JF
Howard
Xiao
X
Xiao
D000256:Adenoviridae / Q000235:genetics*; D000818:Animals; D000831:Animals, Newborn; D015153:Blotting, Western; D004285:Dogs; D016189:Dystrophin / Q000172:deficiency* / Q000235:genetics / Q000378:metabolism*; D005260:Female; D015316:Genetic Therapy / Q000379:methods*; D005822:Genetic Vectors / Q000008:administration & dosage / Q000235:genetics*; D006801:Humans; D007275:Injections, Intravenous / Q000379:methods*; D008279:Magnetic Resonance Imaging; D009132:Muscles / Q000378:metabolism* / Q000473:pathology; D009137:Muscular Dystrophy, Animal / Q000235:genetics / Q000378:metabolism / Q000628:therapy
D016189:Dystrophin