Adeno-associated virus 2-mediated gene transfer and functional expression of the human granulocyte-macrophage colony-stimulating factor.

It is becoming increasingly clear that the adeno-associated virus 2 (AAV)-based vector system may prove to be useful for high-efficiency gene transfer in human cells as well as for potential gene therapy in humans. A recombinant AAV vector containing the gene for a human hematopoietic growth factor, granulocyte-macrophage colony-stimulating factor (GM-CSF), was constructed and used to infect COS-1 cells, a monkey kidney cell line. COS-1 cells infected with the recombinant virus, but not mock-infected cells, expressed high levels of the human GM-CSF gene transcripts. Furthermore, in co-cultivation experiments with the recombinant virus-infected cells, but not in those with mock-infected cells, active proliferation of a GM-CSF-dependent human megakaryocytic leukemia cell line, M07e, could be obtained in the absence of exogenously added GM-CSF. The recombinant GM-CSF protein released into the supernatant was biologically active in progenitor cell assays carried out with primary human hematopoietic cells, and this activity was specifically abrogated by treatment of the supernatant with anti-GM-CSF antibodies. This recombinant virus may be potentially useful in the management and gene therapy of a variety of malignant disorders in the human hematopoietic system.