Non-Irradiation Approach To Study Hematopoiesis and Leukemogenesis In a De Novo Murine Model Of Hematopoietic/Leukemia Stem Cell Transplant

Traditional mouse models for hematopoietic stem cell transplant (HSCT) require whole body irradiation to ablate the hematopoietic cells in recipients, with the defect of disturbing non-hematopoietic cells and introducing potential tumorgenesis in a nonautonomous manner. Here, we use a novel approach to produce mice that whole hematopoietic-specific ablation can be conditionally achieved without global body irradiation. Briefly, a Diphtheria toxin receptor (DTR)-GFP reporter element was targeted into the ROSA26 locus to produce DTR-GFP reporter mice, with a loxp-stop-loxp cassette. Then the DTR-GFP reporter mice were crossed to Vav-Cre mice to produce double transgenic mice (DTR-GFP mice). We injected DT to ablate the bone marrow cells from DTR-GFP mice, and transplant WT bone marrow cells into them. Our data showed that all hematopoietic cells including hematopoietic stem cells, Myeloid, lymphoid lineages are GFP positive in DTR-GFP mice. A single dose of DT can kill all the hematopoietic cells from DTR-GFP mice. One month later, WT bone marrow cells were successfully engrafted into the DTR-GFP recipients without irradiation. We are using this model to re-evaluate some leukemia models that irradiated bone marrow niches might be involved in the tumorigenesis.Thus, we establish a de novel HSCT approach without irradiated myeloablation, which will benefit studies of hematopoiesis, leukemogenesis, hematopoietic stem cell niche, as well as other types of tissue transplants that need ablation of recipient hematopoietic system or immune system.