Malignant stem cells in childhood acute lymphoblastic leukemia: the stem cell concept revisited.

We have recently shown that in childhood acute lymphoblastic leukemia (ALL) blasts at different stages of immunophenotypic maturation possess stem cell properties. Here, we discuss our results in the context of previous investigations of ALL stem cells and recent studies highlighting specific limitations of the xenotransplantation models for human hematopoietic cells. Leukemia-propagating stem cells in ALL may be more frequent than previously thought!