Slug-deficient BM shows enhanced long-term repopulating ability in vivo. (A) Relative repopulating ability of Slug^−/− and Slug^+/− HSCs in recipients. Equal number (2 × 10⁵) of Slug^−/− and Slug^+/− BM cells (test cells, CD45.2⁺) were cotransplanted with wild-type competitor BM cells (CD45.1⁺/ CD45.2⁺) into lethally irradiated recipient mice (CD45.1⁺, n = 8 for each group). The relative repopulating ability of test cells was determined by the percentage of CD45.2⁺ with total donor-derived cells (CD45.2⁺ and CD45.1⁺/ CD45.2⁺ cells) in blood at 8 weeks and 16 weeks after BM transplantation. There is a significant difference between the 2 groups of reconstituted mice (**P < .01 for Slug^−/− vs Slug^+/−). (B) Multilineage distribution (4 months after BM transplantation) in Slug^+/− BM (test, CD45.2⁺)–derived and wild-type competitor cell (CD45.1⁺/ CD45.2⁺) population-derived hematopoietic cells of recipients (n = 8) transplanted with Slug^+/− BM donors. There is no significant difference in the percentage of T, B, and myeloid cells derived from transplanted donor cells from Slug^+/− mice and competitive cells. (C) Multilineage distribution (4 months after BM transplantation) in Slug^−/− BM (test, CD45.2⁺) donor-derived and wild-type competitor cell (CD45.1⁺/CD45.2⁺) population-derived hematopoietic cells of recipients (n = 8) reconstituted with Slug^−/− BM. There is no significant difference in the percentage of T, B, and myeloid cells derived from transplanted donor cells from Slug^−/− mice and competitive cells. (D) Diagram of BM homing assay for primitive hematopoietic cells. Test BM cells (CD45.2⁺) from mice were equally mixed with wild-type competitor BM cells (CD45.1⁺/CD45.2⁺), and the ratio of Lin⁻Sca-1⁺ cells in test vs competitor cells (the number of Lin⁻Sca-1⁺ cells in test BM cells to the number of Lin⁻Sca-1⁺ cells in competitor BM cells) was determined by flow cytometry before being injected into lethally irradiated recipients (CD45.1⁺). Sixteen hours after BM injection, the ratio of Lin⁻Sca-1⁺ cells in test vs competitor cells (the percentage of CD45.2⁺ Lin⁻Sca-1⁺ cells to the percentage of CD45.1⁺/CD45.2⁺ Lin⁻Sca-1⁺ cells) was determined and compared with the ratio of these cells before BM injection. (E) Relative homing ability of Lin⁻Sca-1⁺ primitive hematopoietic cells from Slug^−/− or Slug^+/− mice. The graph indicates that the ratio of Lin⁻Sca-1⁺ cells in test (Slug^−/− or Slug^+/−) BM cells vs competitor cells was comparable in recipients (n = 4). (F) Chimerism in recipients transplanted with BM cells of Slug^−/− or Slug^+/− mice. Limiting numbers (5 × 10⁴ and 2 × 10⁵) of BM cells from Slug^−/− or Slug^+/− mice were cotransplanted with 2 × 10⁵ competitor cells (CD45.1⁺/CD45.2⁺) into 2 groups of recipients (n = 8 for each group). Chimerism was analyzed by flow cytometric analysis of peripheral blood cells 4 months after BM transplantation. In each animal, 1% or higher of donor-derived (CD45.2⁺) cells containing T, B, and myeloid cell was defined as positive engraftment. **P < .01 for Slug^−/− vs Slug^+/−.