Unexpectedly efficient homing capacity of purified murine hematopoietic stem cells

Single-cell transplantation analysis revealed that the cells that had the strongest dye efflux activity (Tip-SP cells)and had the phenotype CD34- c-Kit+ Sca-1+ Lin- (CD34- KSL cells) exhibited very strong proliferation and multilineage differentiation capacity. Ninety-six percent of the lethally irradiated mice that received a single Tip-SP CD34- KSL cell showed significant donor cell engraftment for long term. These findings support the hypothesis that Tip-SP CD34- KSL cells represent the most primitive hematopoietic stem cells that are capable of migrating into the primary site and surviving and/or proliferating with nearly absolute efficiency. This led us to propose high marrow-seeding efficiency as a specific characteristic of primitive HSCs, in addition to their self-renewal and multipotent capacity.