Stable long-term gene correction with low-dose radiation conditioning in murine X-linked chronic granulomatous disease.

We previously demonstrated that low-dose radiation conditioning impairs murine hematopoietic stem cell function, permitting engraftment of syngeneic fresh and transduced marrow cells. In this study, we directly examined the ability of low-dose radiation conditioning to permit engraftment of transduced long-term repopulating cells in murine X-linked chronic granulomatous disease (X-CGD), which closely mimics the human disease. X-CGD mice conditioned with 160 cGy were transplanted with 20 x 10(6) MSCV-m91Neo-transduced syngeneic X-CGD marrow cells. The presence of oxidase-positive neutrophils in two independent cohorts of transplanted 160-cGy-conditioned X-CGD recipients was determined by nitroblue tetrazolium testing. Transplanted X-CGD mice (n = 9 total) displayed 1-17% oxidase-positive neutrophils 6-16 months post-transplant. Retroviral marking and NADPH-oxidase-positive neutrophils persisted through serial transplantation, verifying that stem cells were transduced. These results establish that low-dose radiation conditioning results in durable engraftment of low but potentially clinically relevant numbers of functionally reconstituted blood cells in a murine model of X-CGD.