Transgenic expression of ASXL1^aa1-587affects HSC pool in vivo. (A) Flow cytometric analysis of Gr-1⁺/Mac1⁺ cell population in PB of representative WT (left) and Asxl1^Y588XTg mice (right, 8 months old). (B) Quantitation of the percent of Gr-1⁺/Mac1⁺ cell populations in PB (*P = .024), BM (P = .074), and spleen (P = .080) of WT and Asxl1^Y588XTg mice. Data are presented as mean ± SEM from 8 to 11 WT and Asxl1^Y588XTg mice (8-19 months old). Unpaired Student t test was used to assess statistical significance. (C) Flow cytometric analysis of LSK compartments in BM of representative WT and Asxl1^Y588XTg mice (8-19 months old) (left). Cells are gated on Lin⁻ cells. Quantitation of the percentage of LSK compartments in BM Lin⁻ of WT and Asxl1^Y588XTg mice (right), n = 8 per group; **P = .002. (D) Flow cytometric analysis of the percent LT-HSC, ST-HSC, and multipotent progenitor cell populations (LSK/CD34⁺/FLK2⁺) in the BM LSK cells of representative WT and Asxl1^Y588XTg mice (8-19 months old) (left). Cells are gated on LSK cells. Quantitation of the percent LT-HSC (P = .089) and ST-HSC (***P = .0006) populations in the BM Lin⁻ cells of each genotype of mice (right). Unpaired Student t test was used to assess statistical significance. (E) Flow cytometric analysis of the GMP, common myeloid progenitor, and MEP populations in the BM LKS⁻ cells of representative WT and Asxl1^Y588XTg mice (8-19 months old) (left). Cells are gated on LKS⁻ cells. Quantitation of the percent GMP (**P = .002) and MEP (**P = .0098) populations in the BM Lin⁻ cells of each genotype of mice (right). Blue square, MPN; red square, leukemia; blue triangle, MDS/MPN; red triangle, MDS. (F) Colonies from 15 000 bone marrow mononuclear cells of WT and Asxl1^Y588XTg mice. Blue bars, CFU-granulocytes/macrophages (GM); green bars, burst forming unit-erythrocyte (BFU-E); red bars, granulocyte, erythroid, macrophage, megakaryocyte (GEMM). Three mice per genotype were analyzed. ***P = .000424. (G) Serial cell replating assays using whole BM cells (3 mice per genotype) were performed to determine HSC self-renewal capability. A total of 15 000 bone marrow mononuclear cells were used for each methylcellulose cultures. The cells were replated weekly for 4 weeks. *P < .05. (H) Monthly assessment of donor chimerism (line II) in the peripheral blood of recipient animals is shown up to 16 weeks after transplant (n = 5 recipient mice were used for each genotype).