Targeting transgene to the heart and liver with AAV9 by different promoters

Adeno-associated virus (AAV) has become one of the most promising gene transfer tools for gene therapy. This work aims to evaluate tropism, gene transfer efficiency and safety of AAV9 vectors produced with recombinant baculovirus (rBac)-based system. AAV9-CMV-GFP and AAV9-CBA-GFP were produced using a rBac system, 1 × 10(11) particles of each vectors were administered intravenously (i.v.) into mice and animals were killed at 1, 2, 3, 4, 5 and 8 weeks after administration. The GFP expression in different organs was analyzed by fluorescence imaging and Western blot. Viral genomic quantities were measured using qPCR. In vitro transduction efficiency of AAV9 vectors in primary cardiomyocytes and hepatocytes was determined by flow cytometry. Toxicity of AAV9 vectors was evaluated by determining certain cardiac and liver injury biomarkers and renal function test in vivo and TUNEL analysis in vitro. The data showed that AAV9 viral particles packaged by the rBac system were fully functional in vivo and in vitro. The CMV promoter predominantly induced higher cardiac GFP transgene expression and DNA copy numbers while the CBA promoter resulted in robust GFP expression and high vector DNA copy numbers in mouse liver, both in a time-dependent increased manner. Such distinct preferential effects were also observed in the heart and liver as early as 3 and 5 days after co-infection. Both the AAV9-CMV and AAV9-CBA viral packages did not induce heart, liver and renal damage and cell apoptosis. These results indicated that AAV9-CMV can efficiently and safely direct cardiac gene transfer, whereas AAV9-CBA is preferential for liver gene delivery.