Characteristics of leukemia stem cells of murine myeloproliferative disease involving the liver.

We studied surface phenotype of tumor cells and characterized leukemia stem cells in various cell populations with phenotypes of stem and committed precursor cells in the hierarchy of hemopoietic stem cells. Transplantable murine leukemia was used as the model. Bone marrow and liver cells from mice in the terminal phase of the disease were stained with antibodies to various surface markers and analyzed on a flow cytofuorometer. The cells were sorted by various differentiation markers using a system of magnetic separation Miltenyi Biotec MACS and then transplanted to syngeneic recipients. In some cases, limiting dilutions were used for measuring the concentration of leukemia-initiating cells. All transplanted cell populations caused death of recipients: c-kit- CD45- over 23.9 days, c-kit+ over 22.2 days, c-kit- CD45+ over 15.4 days, Ter119+ over 18.2 days, and Ter119- over 17.7 days. The concentrations of leukemia cells determined by the method of limiting dilutions was 1 per 37,000 c-kit+ bone marrow cells and 1 per 45 unsorted liver cells from sick animals. Thus, leukemia stem cells retain hierarchic organization in the studied model and can differentiate at least into myeloid and erythroid cells without loosing self-maintenance capacity. This model can be used for the study of regulation of self-maintenance mechanisms in various hierarchic populations of leukemia stem cells.