Autocrine and paracrine effects of an ES-cell derived, BCR/ABL-transformedhematopoietic cell line that induces leukemia in mice

During differentiation in vitro, Embryonic Stem (ES) cells generate both pr imitive erythroid and definitive myeloid lineages in a process that mimics hematopoiesis in the mammalian yolk sac, To investigate leukemic transforma tion of these embryonic hematopoietic progenitors, we infected differentiat ing cultures of ES cells with the Chronic Myeloid Leukemia-specific BCR/ABL oncoprotein. Following a period of liquid culture, we isolated two transfo rmed subclones, EB57 and EB67, that retained characteristics of embryonic h ematopoietic progenitors and induced a fatal leukemia in mice characterized by massive splenomegaly and granulocytosis, Histopathology of the spleen r evealed an abundance of undifferentiated blast-like cells. Investigation of the clonal origins of the granulocytes in the peripheral blood demonstrate d that the injected donor cells contributed modestly to the granulocyte pop ulation while the majority were host-derived, EB57 secretes IL-3 and uniden tified cytokines that can stimulate autocrine and paracrine cell proliferat ion, presumably accounting for the reactive granulocytosis in diseased mice . These BCR/ABL transformed hematopoietic derivatives of ES cells recapitul ate the relationship of BCR/ABL expression to IL-3 production that has been described for primitive hematopoietic progenitors from human CML patients, and illustrates the potential for autocrine and paracrine effects of BCR/A BL-infected cells in murine models.