The use of nonmyeloablative conditioning prior to bone marrow transplantation is an important component of transplantation-based therapies for nonmalignant blood diseases. In this study, treatment of recipient mice with granulocyte colony-stimulating factor (G-CSF) prior to low-dose total body irradiation (LD-TBI) enhanced longterm engraftment of freshly isolated congenic marrow 1.5- to 2-fold more than treatment with LD-TBI alone. This combined regimen was also evaluated in a mouse model of X-linked chronic granulomatous disease (XCGD), where neutrophils have a defective NADPH oxidase due to genetic deletion of the gp91phox subunit. Long-term engraftment of male X-CGD bone marrow cells cultured ex vivo for retroviral transduction of gp91 phox was enhanced by ∼40% when female X-CGD recipients were pretreated with G-CSF prior to 300 cGy. These data confirm that sequential treatment with G-CSF and LDTBI prior to transplantation increases long-term engraftment of donor marrow, and they extend this approach to transplantation of murine donor marrow cultured ex vivo for gene transfer. Additional studies showed that the administration of G-CSF prior to LD-TBI did not alter early homing of donor marrow cells. However, the combined regimen significantly decreased the content of longterm repopulating cells in recipient marrow compared with LD-TBI alone, as assessed in competitive assays, which may contribute to the enhanced engraftment of donor marrow cells.
- Bone marrow transplant
- Gene therapy
- Granulocyte colony-stimulating factor