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Gao G.,University of Massachusetts Medical School | Bish L.T.,University of Pennsylvania | Sleeper M.M.,Veterinary Hospital | Mu X.,University of Massachusetts Medical School | And 6 more authors.
Human Gene Therapy | Year: 2011

Heart disease is the leading cause of morbidity and mortality, and cardiac gene transfer has potential as a novel therapeutic approach. We previously demonstrated safe and efficient gene transfer to the canine heart using a percutaneous transendocardial injection procedure to deliver self-complementary (sc) adeno-associated virus 6 (AAV6) vector. In the present study, we proceed with our vertical translation study to evaluate cardiac gene transfer in nonhuman primates (NHPs). We screened approximately 30 adult male rhesus macaques for the presence of neutralizing antibodies against AAV6, AAV8, and AAV9, and then selected seven monkeys whose antibody titers against these three serotypes were lower than 1/5. The animals were then randomized to receive either scAAV6 (n=3), scAAV8 (n=1), or scAAV9 (n=3) vector expressing the enhanced green fluorescent protein (EGFP) reporter gene at a dose of 5.4×10 12 genome copies/kg, which was administered according to a modified version of our previously developed transendocardial injection procedure. One animal treated with scAAV6 died secondary to esophageal intubation. The remaining animals were euthanized 7 days after gene transfer, at which time tissue was collected for analysis of EGFP expression, histopathology, and biodistribution of the vector genome. We found that (i) transendocardial delivery of AAV is safe in the NHP, (ii) AAV6 and AAV8 provide efficient cardiac gene transfer at similar levels and are superior to AAV9, and (iii) AAV6 is more cardiac-specific than AAV8 and AAV9. The results of this NHP study may help guide the development AAV vectors for the treatment of cardiovascular disease in humans. © 2011 Mary Ann Liebert, Inc.

Sun L.,University of Sichuan | Tu L.,University of Sichuan | Gao G.,University of Massachusetts Medical School | Sun X.,University of Sichuan | And 2 more authors.
Journal of Immunological Methods | Year: 2013

Adeno-associated viruses (AAVs) are common infective agents of primates. As such, healthy primates carry a large pool of AAV-specific neutralizing antibodies (NAbs), which inhibit AAV-mediated gene transfer therapeutic strategies. Thus, a clinical method to screen patient candidates for AAV-specific NAbs prior to treatment, especially with the frequently used AAV8 capsid component, will facilitate individualized treatment design and enhance therapeutic efficacy. In this study, we evaluated the efficacy and sensitivity of a passive immunity mouse model to quantitatively assess anti-AAV8 NAb titers, as compared to an in vitro immunoassay. The passive transfer model was established in C57BL/6 mice by tail vein injection of pre-defined sera from 23 male rhesus monkeys. The mice were then administered low dose (3e10 GC/mouse) self-complementary (sc) AAV8. The in vitro NAb assay indicated that 69.57% of the rhesus donors had pre-existing anti-AAV8 NAb. The in vivo NAb assay, however, was better able to detect low NAb titer (≤ 1:5), which can mediate neutralization in vivo. Indeed, 17 rhesus donors (74.0%) had pre-existing anti-AAV8 neutralization by in vivo NAb assay. Our findings indicated that the in vivo NAb assay is superior to the in vitro assay for detecting low NAb titers. © 2012 Elsevier B.V.

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