Retroviral interleukin 1α gene transfer in bone marrow stromal cells in a primate model: induction of myelopoiesis stimulation

Summary. Effects of interleukin 1-α (IL-1α), a proinflammatory cytokine with pleiotropic activity, in the myelopoietic setting, is mainly linked to its ability to increase haematopoietic growth factor production by bone marrow stromal cells. In order to minimize systemic effects of IL-1α therapy, we proposed a model of retroviral IL-1α gene transfer within bone marrow stromal cells in the macaque cynomolgus. Invitro, 10–15% of bone marrow stromal cells was effectively transduced by retroviral vector (murine Moloney leukaemia virus-derived) expressing IL-1α/LacZ, or LacZ alone as control marker, as assessed by βGal staining. IL-1α gene expression was upregulated [semiquantitative reverse transcription polymerase chain reaction (RT-PCR)] within the transduced cells and the cell supernatant showed an increased production of granulocyte colony-stimulating factor (G-CSF) and granulocyte–macrophage (GM)-CSF (enzyme-linked immunosorbent assay) and an increased clonogenic activity (colony-forming cell assay). Ex vivo autologous expanded IL-1α/LacZ transduced bone marrow stromal cells were reinfused in two macaques (and two control animals for LacZ alone as controls), without clinical systemic toxicity; LacZ expression by RT-PCR was detected in one animal of each group between d 4 and 9. A slight increase of the peripheral blood leucocyte counts (both polymorphonuclear cells and monocytes) of the two animals transduced with IL-1α/LacZ was observed within 10 d, indicating stimulation of myelopoiesis.