Multilineage outgrowth of both malignant and normal hemopoietic progenitorcells from individual chronic myeloid leukemia patients in immunodeficientmice

In this study the ability of malignant and normal progenitors in peripheral blood (PB) and bone marrow (BM) of CML patients in chronic phase to prolif erate and produce mature progeny after transplantation into hereditary immu nodeficient (SCID and NOD/SCID) mice was examined. Engraftment in NOD/SCID mice preconditioned by total body irradiation (TBI) alone was 10-fold highe r than in SCID mice preconditioned by macrophage depletion and TBI, demonst rating that NOD/SCID mice are more suitable for engraftment of chronic phas e CML cells. Low-density cells at cell doses of 10-30 x 10(6) and purified CD34(+) cells at doses of approximately 0.2 x 10(6) engrafted NOD/SCID mice , with levels of 2 to 20% CD45(+) cells with production of monocytes, granu locytes, erythroid cells, B-lymphocytes, CD34(+) cells and variable frequen cies of erythroid and myeloid colony-forming cells. As demonstrated by fluo rescent in site hybridization (FISH) analysis, purified human myeloid, B-ly mphoid, erythroid and CD34(+) cells from chimeric mouse BM contained Philad elphia-chromosome (Ph)-positive cells and Ph- cells in similar frequencies as primary cells from the CML patients. These results demonstrate that prod uction of mature normal as well as malignant cells of multiple lineages wer e supported with similar efficiency. In contrast, all human erythroid and m yeloid clonogenic cells detected in the mice were Ph-, which can be attribu ted to less efficient maintenance or more rapid differentiation of immature Ph+ cells in the mouse microenvironment. CML blast crisis cells also grew well in NOD/SCID mice, with 80-90% of human cells produced containing the P h-chromosome. The availability of an in vivo assay that supports outgrowth of normal and malignant stem cells from chronic phase and blast crisis CML patients will facilitate examination of differential effects of growth fact ors, inhibitory cytokines and cytotoxic drugs on survival of normal and mal ignant stem cells in vivo and on progression of chronic phase CML towards b last crisis.