What do the lineage tracing studies tell us? Consideration for hematopoietic stem cell origin, dynamics, and leukemia-initiating cells.

The recent advance of technologies enables us to trace the cell fate in vivo by marking the cells that express the gene of interest or by barcoding them at a single cell level. Various tamoxifen-inducible Cre-recombinase mice combined with Rosa-floxed lines are utilized. In this review, with the results revealed by lineage tracing assays, we re-visit the long-standing debate for the origin of hematopoietic stem cells in the mouse embryo, and introduce the view of native hematopoiesis, and possible leukemic-initiating cells emerged during fetal stages.