CD150− and CD150⁺ HSCs exhibit differences in contribution to various hematopoietic compartments 24 weeks after transplantation. (A) A significant decrease in donor-derived whole bone marrow (WBM) and thymus engraftment, measured by flow cytometry, was observed for CD150⁻ SP^KLS HSCs compared with CD150⁺ or whole SP^KLS HSCs. No statistical difference was observed for donor-derived peripheral blood and spleen chimerism. (B) All 3 populations of SP^KLS cells self-renew to give rise to comparable levels of SP^KLS, although CD150⁻ SP^KLS generate lower levels of KLS, MP, and CLP compartments as measured by flow cytometry. (C) WBM was examined for the presence of donor-derived CD150⁺ and CD150⁻ SP^KLS within transplant recipients that received CD150⁺ or CD150⁻ SP^KLS cells. Both donor populations were able to produce CD150⁺ and CD150⁻ SP^KLS cells, indicating no clear-cut hierarchy between the CD150⁺ and CD150⁻ SP^KLS cells. In addition, CD150⁺ SP^KLS donor cells exhibited a trend toward generating a higher proportion of CD150⁺ cells in the recipient SP. This result, although not statistically significant, suggests a preference for the CD150⁺ SP^KLS to preferentially produce CD150⁺ SP^KLS on transplantation. Error bars represent SEM.