RETROVIRAL-MEDIATED GENE-TRANSFER INTO CD34-ENRICHED HUMAN PERIPHERAL-BLOOD STEM-CELLS

Retroviral-mediated gene transfer has been shown to be a feasible meth od for the introduction of new genes into bone marrow hematopoietic st em cells. We have investigated the application of this technology to p rimitive CD34-enriched human peripheral blood cells as a potential alt ernative stem cell source. Bone marrow (BM) and peripheral blood (PB) CD34-enriched cells from normal volunteers and patients with multiple myeloma were exposed to retroviral vectors containing the neomycin-res istance gene and gene transfer efficiency into colony-forming unit col onies (CFU-C) and CD34(+) cells was assessed by polymerase chain react ion (PCR). Peripheral blood was a target equally efficient to BM, and PB cells mobilized with chemotherapy and growth factors were also show n to take up retroviral vectors readily. Conditions favoring gene tran sfer were investigated, and exposure of cells to interleukin-3 (IL-3), interleukin-6 (IL-6), and stem cell factor (SCF) during a 72-hour tra nsduction was found to be most effective. The use of PB stem cells as targets for gene transfer could allow repeated collections and transdu ctions, with obvious advantages over a single BM collection.