Adeno-associated virus serotype 2 mediated transduction and expression of the human β-globin gene in human early fetal liver hematopoietic cells

beta-Thalassemia is an inheritance anaemia disease due to the defect in beta- globin gene. Gene therapy is considered to be the only method which could cure this disease. Adeno-associated virus type 2 (AAV2) has benn gaining more attention as a vector in human gene therapy for its non pathogenic character and broad host range. Although, the efficacy of recombinant AAV2 (rAAV2) in transducing human hematopoietic stem cells has been investigated by researchers, the results were varied from different laboratory. The view was proposed recently that it may be resulted from helper virus in their packaging system. Respecting this, the packaging system without helper virus was used to produce rAAV2. Human early fetal liver hematopoietic cells not only possess many superior peculiarity compared to hematopoietic cells of bone marrow or cord blood, but also the inherent P-globin gene in the cells is not expressed. Studies on the AAV2 transduction of human fetal liver hematopoietic cells and mediated expression of beta- globin gene in vivo were performed and the potential role of AAV2 in beta-thalassemia gene therapy was analyzed. The rAAV2 containing a normal human P-globin gene (rAAV2-beta-globin) without helper virus contamination were produced. The viral titer, purity and the ability of mediating expression of P-globin gene were detected in vitro. Then, human early fetal liver hematopoietic cells were isolated and were further transducted with the rAAV2-beta-globin, followed by transplantation into sublethally irradiated BALB/C nude mice to analyze the P-globin gene expression. The results showed that the high titer and purity of rAAV2-beta-globin had the ability of mediating P-globin gene expression in vitro. In 8 recipient BALB/C nude mice, the P-globin gene expression were detected in the 2 mice marrow by RT-PCR. The results suggested that rAAV2 could transduce human fetal liver hematopoietic cells and mediate the P-globin gene expression in BALB/C nude mice, meanwhile the expression level of the gene was still rather low. It is necessary to perform further research on AAV2 biology before applying in beta-thalassemia gene therapy.