Abstract
There is still an unmet need for xenotransplantation models that efficiently recapitulate normal and malignant human hematopoiesis. Indeed, there are a number of strategies to generate humanized mice and specific protocols, including techniques to optimize the cytokine environment of recipient mice and drug alternatives or complementary to the standard conditioning regimens, that can be significantly modulated. Unfortunately, the high costs related to the use of sophisticated mouse models may limit the application of these models to studies that require an extensive experimental design. Here, using an affordable and convenient method, we demonstrate that the administration of fludarabine (FludaraTM) promotes the extensive and rapid engraftment of human normal hematopoiesis in immunodeficient mice. Quantification of human CD45+ cells in bone marrow revealed approximately a 102-fold increase in mice conditioned with irradiation plus fludarabine. Engrafted cells in the bone marrow included hematopoietic stem cells, as well as myeloid and lymphoid cells. Moreover, this model proved to be sufficient for robust reconstitution of malignant myeloid hematopoiesis, permitting primary acute myeloid leukemia cells to engraft as early as 8 weeks after the transplant. Overall, these results present a novel and affordable model for engraftment of human normal and malignant hematopoiesis in immunodeficient mice.
Highlights
In the 2000s, various immunodeficient models were developed by combining the IL-2rgnull gene with conventional Prkdcscid and Rag1/2null mutations
Within the context of bone marrow (BM) transplantation, fludarabine has been mainly administered in graft-versus-host disease mouse models[12,13,14]
We decided to adopt the SCID/beige mouse model based on the fact that if mice are conditioned with a sublethal dose of irradiation, they exhibit low levels of human engraftment[15]
Summary
In the 2000s, various immunodeficient models were developed by combining the IL-2rgnull gene with conventional Prkdcscid and Rag1/2null mutations. 10 independent experiments (2–4 mice/experiment); (D) SCID/beige mice receiving irr+ fluda or irr were weighed over 6 weeks following the conditioning procedure (on left) and their blood was collected at sacrifice for testing white blood cells (WBC), platelets (PLT) and hemoglobin (Hb) (on right). 2 independent experiments (3 mice/group in each experiment); (H) Levels of human chimerism analysed in PB and BM of recipient mice at 2, 4 and 6 weeks after conditioning with irr+ fluda. 2 independent experiments (2–3 mice/experiment); (I) Long term human engraftment (at 12 weeks) in irr+ fluda treated mice and presence of hCD34+ precursors Proportion and absolute numbers of hCD45+ cells in the same groups. 10 independent experiments (2–4 mice/experiment); (F) Relative proportion of myeloid (CD33+) and B lymphoid (CD19+) cells within the human graft in irr+ fluda mice at 6 weeks. 2 independent experiments (2–3 mice/experiment); (G) Frequency of donor hematopoiesis in PB 4 and 6 weeks after transplantation of mice irradiated (200, 400 or 850 cGy), treated or not with fludarabine and injected with 0.5 or 0.05 × 106 BM cells of congenic mice. 2 independent experiments (3 mice/group in each experiment); (H) Levels of human chimerism analysed in PB and BM of recipient mice at 2, 4 and 6 weeks after conditioning with irr+ fluda. 2 independent experiments (2–3 mice/experiment); (I) Long term human engraftment (at 12 weeks) in irr+ fluda treated mice and presence of hCD34+ precursors
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