Unbiased lineage tracing of long-term HSCs in vivo at steady-state

The various cell types of the hematopoietic system have previously been well characterized, butan important question that remains in the field is how the small population of long-term HSCs contribute to steady-state hematopoiesis. Investigating the lineage relationships of this system not only provides valuable information about normal development, but also for developmental disorders and malignancies. Our hoxb5-CreERt2 lineage tracing model allows us to track labeled daughter cells and perform stem cell clonal analysis at varying timepoints. From our tracing studies, we have seen that hoxb5+ LT-HSCs have a limited contribution to steady-state hematopoiesis, and their contribution does not expand under stress by lymphocyte depletion.