Functional differences between two Tie2 ligands, angiopoietin-1 and -2, in regulation of adult bone marrow hematopoietic stem cells

Gene expression analysis and BM transplantation assay demonstrated that Ang-1 maintained HSC activity in an in vitro culture. In contrast, Ang-2 reversed the effects of Ang-1/Tie2 signaling in the regulation of long-term HSCs. Our data suggest that Ang-1 is a dominant ligand for the Tie2 receptor in long HSCs in BM.