Efficient and durable gene transfer to transplanted heart using adeno-associated virus 9 vector

Background: In this investigation we studied the efficacy and durability of recombinant adeno-associated virus serotype 9 (rAAV9) vector-mediated gene transfer to the transplanted rat heart. Methods: A rAAV9-CMV-lacZ vector diluted in cold (4 degrees C) University of Wisconsin solution was used to perfuse the rat coronary vasculature for 20 minutes prior to syngeneic heterotopic transplantation. Perfusion experiments (six groups, n = 3/group) were performed without rAAV9 and at four separate doses ranging from 2 X 10(9) to 2 X 10(12) viral genomes/ml. The transplanted heart was recovered 10 days or 3 months after transplantation and expression of lacZ assessed by histology, enzyme-linked immunoassay and real-time reverse transcript-polymerase chain reaction (RT-PCR). In a final group (n = 3), rAAV9 was administered systemically to compare the cardiac transduction efficiency and viral distribution to other organs. Results: Transduction efficiency of perfused virus correlated with vector dose (p < 0. 000 1), with myocardial transduction ranging up to 71.74% at the highest dose. Cardiac expression of lacZ was equivalent at 10 days and 3 months. There was no evidence of viral gene transfer to other organs after heart transplantation. Conclusions: Our findings demonstrate efficient and durable rAAV9-mcdiated gene transfer to the transplanted heart after ex vivo perfusion and suggest that AAV9 is a promising vector for cardiac gene therapy.