Progress in the leukemic stem cell study and a novel therapeutic approach targeting leukemic stem cells.

Hematopoietic stem cells (HSCs) have the potential to self-renew and differentiate into multi-lineage mature hematopoietic cells; thus, these cells can maintain hematopoiesis. Human HSCs reside within the CD34+CD38- cell fractions. Similarly, in acute myelogenous leukemia (AML), a small number of leukemic cells, called leukemic stem cells (LSCs), can be enriched within the identical CD34+CD38- cell fractions. LSCs can self-renew and produce clonogenic leukemic cells, whereas non-LSCs lack the potential to self-renew or maintain leukemia; thus, AML is organized as a hierarchy that originated from LSCs. LSCs play a central role in the maintenance and progression of leukemia; therefore, these cells should be an ultimate target for the eradication of human AML. Previous studies have revealed specific molecular machineries essential for LSCs. Targeting LSC-specific molecules should be a good therapeutic approach to kill LSCs without affecting normal cells. In this review, we would like to introduce the recent progress in the LSC study.