Direct Transplantation of Chronic Myelogenous Leukemia Cells into Nude Mice and Establishment of a Leukemic Stem Cell (Ph(1+), CD34(+)) Line Dependent on Mouse Bone Marrow Stromal Cells in vitro

Peripheral blood cells from a female patient with Ph(1)‐positive chronic myelogenous leukemia (CML) in blast crisis were serially transplanted in BALB/c nude mice for 16 passages. This in vivo cell line, designated CML‐N‐1, had Ph(1)chromosome abnormality and BCR gene rearrangement. The cells expressed CD11b, CD13, CD33, CD34, CD38, and HLA‐DR antigens until the 11th passage and subcutaneous tumors produced by these passages were composed of admixtures of immature and maturing cells that differentiated to basophils when cultured in vitro. From the 12th passage on, the tumors became composed mainly of immature cells expressing CD13, CD34, and HLA‐DR, and no longer differentiated to basophils even upon in vitro culture. In contrast to the vigorous proliferation in vivo, CML‐N‐1 cells from any passage failed to proliferate in vitro under standard liquid culture conditions with or without growth factors, such as granulocyte‐macrophage colony‐stimulating factor, granulocyte colony‐stimulating factor, monocyte colony‐stimulating factor, interleukin 3, interleukin 6 and stem cell factor. However, a continuously growing cell line, designated CML‐C‐1, was established by culturing CML‐N‐1 cells on feeder layers of mouse bone marrow stromal cells. This mouse bone marrow stromal cell‐dependent cell line showed immature cell morphology and expressed early myeloid phenotype positive for CD13, CD34, and HLA‐DR. These results indicate that mouse bone marrow stromal cells provide a certain growth factor(s) active on human leukemia cells.