Identification of leukemia initiating cells in pediatric acute lymphoblastic leukemia

Conflicting data on the nature of leukemia initiating cells (LICs) in acute lymphoblastic leukemia (ALL) have prompted us to functionally characterize LICs defined by high repopulating activity upon xenotransplantation. We sorted ALL cells according to cell cycle (cc) phases followed by transplantation onto NOD/SCID mice. All sub-fractions led to engraftment. Cells of G0/G1 cc phases led to early leukemia onset in contrast to cells from late cc (G2/M). Strikingly, this difference was maintained upon secondary transplantation. Additionally, we addressed the oxidative state of ALL cells by assessing reactive oxyge…