Impaired repopulation in Meis1^−/− LT-HSCs. Repopulation assays: (A) LT-HSCs (Lin⁻Sca1⁺Kit⁺Flk2⁻CD34⁻; 150 cells) from either control (Meis1^+/+) or mutant Meis1^−/− CD45.2 mice were transplanted into irradiated CD45.1 hosts in competition with BM from CD45.1 mice (1 × 10⁵ cells). Quantification of flow cytometry profile of peripheral blood of bone marrow recipient mice up to 16 weeks for percentage of CD45.2⁺ cells demonstrates total loss of bone marrow reconstitution of Meis1^−/− LT-HSCs (n = 5). (B) Repopulation assay with whole bone marrow from either control Meis1^+/+ or mutant Meis1^−/− CD45.2 mice were transplanted into irradiated CD45.1 mice demonstrates significantly impaired repopulation in mice transplanted with Meis1^−/− cells (n = 5). (C) Analysis of repopulation after second bone marrow transplantation (BMT) from first BMT mice demonstrates complete loss of repopulation (n = 5). Homing assays: (D) BM Lin⁻ cells (3 × 10⁶ cells) were transplanted into irradiated mice and quantified for CFSE⁺ cells in different tissues. Quantification of percentage of CFSE⁺ cells in BM, spleen, and liver show no difference between Meis1^+/+ and Meis1^−/− mice (n = 5). (E) Quantification of percentage of CFSE⁺ LSK cells in BM of Meis1^+/+ and Meis1^−/− mice (n = 5). (F) Quantification of repopulation of lineages for Meis1^−/− using whole bone marrow from first BMT mice demonstrates no defects in lineage repopulation (n = 5); *P < .05, **P < .01.