Improved engraftment of human acute myeloid leukemia progenitor cells in beta 2-microglobulin-deficient NOD/SCID mice and in NOD/SCID mice transgenic for human growth factors

Primitive malignant progenitors defined as nonobese diabetic severe combined immunodeficient (NOD/SCID) leukemia-initiating cells or NOD/SL-IC from patients with acute myeloid leukemia (AML) can be detected and quantitated in sublethally irradiated NOW/SCID mice. However, there is variability in the levels of bone marrow (BM) engraftment obtained after intravenous injection of cells from different AML samples. In the current study, AML cell engraftment in standard NOW/SCID mice was compared to that obtained with NOD/SCID mice transgenic for the human growth factor genes Steel factor (SF), interleukin-3 (IL-3) and granulocyte macrophage-colony-stimulating factor (GM-CSF) (N/S-S/GM/3) as well as beta2 microglobulin-null NOD/SCID (N/S-beta2m(-/-)) mice. Three of the eight AML samples that failed to engraft in standard NOD/SCID animals showed easily detectable and up to 70-fold increased in the number of leukemic cells in BM 8-12 weeks post-transplantation in each of the N/S-beta2m(-/-) and N/S-S/GM/3 mouse strains. In two of the four AML samples studied at limiting dilution, the frequency of NOD/SL-IC detected was increased six- and seven-fold. Thus, in these novel mouse strains a broader spectrum of AML patient samples can be evaluated for their progenitor content and potentially studied for their response to innovative therapeutics in vivo.