Summary of human cell repopulation in the BM, spleen, and peripheral blood of NOD/SCID and NOD/SCID β2M null mice that received transplants with ALDHhiLin- and ALDHloLin- cells. A summary of the level of human engraftment in the BM, spleen, and peripheral blood of NOD/SCID β2M null mice (n = 43) (A-C) or NOD/SCID mice (n = 36) (D-F) that received transplants with purified ALDHhiLin- and ALDHloLin- cells is shown. Mouse BM, spleen, and peripheral blood were extracted 7 to 8 weeks after transplantation, and human cells were detected by coexpression of the pan-leukocyte marker CD45 with CD38. Open squares represent mice injected with 2 × 102 to 1 × 103 purified cells, red squares represent mice injected with 2 × 103 to 1 × 104 purified cells, blue circles represent mice injected with 2 × 104 to 1 × 105 purified cells, and green triangles represent mice injected with 2 × 105 to 4 × 105 purified cells. Horizontal bars represent the average level of human engraftment (mean ± SEM) detected in the tissues of each mouse corresponding to the 2 × 104 to 105 dose range in each mouse strain. Human SCID-repopulating cells were observed exclusively within the ALDHhiLin- fraction. Human cell engraftment was consistently achieved with as few as 500 ALDHhiLin- cells in the NOD/SCID β2M null mouse, whereas more than 104 ALDHhiLin- cells were needed to engraft the parental NOD/SCID strain. Mice received transplants with the cells from 18 UCB samples. Purified cells from 2 UCB samples were pooled to achieve doses of 4 × 105 ALDHloLin- cells.
