In utero delivery of adeno-associated viral vectors: Intraperitoneal gene transfer produces long-term expression

Recombinant adeno-associated viruses (rAAV) are promising gene transfer vec tors that produce long-term expression without toxicity. To investigate fut ure approaches for in utero gene delivery, the efficacy and safety of prena tal administration of rAAV were determined. Using luciferase as a reporter, expression was assessed by whole-body imaging and by analysis of luciferas e activity in tissue extracts, at the time of birth and monthly thereafter. Transgene expression was detected in all injected animals. Highest levels of luciferase activity were detected at birth in the peritoneum and liver, while the heart, brain, and lung demonstrated low-level expression. In vivo luciferase imaging revealed persistent peritoneal expression for 18 months after in utero injection and provided a sensitive whore-body assay, useful in identifying tissues for subsequent analyses. There was no detectable he patocellular injury. Antibodies that reacted with either luciferase or rAAV were not found. AAV sequences were not detected in germ-line tissues of in jected animals or in tissues of their progeny. In utero AAV-mediated gene t ransfer in this animal model demonstrates that novel therapeutic vectors an d strategies can be rapidly tested in vivo and that rAAV may be developed t o ameliorate genetic diseases with perinatal morbidity and mortality.