Phenotypic and functional loss of HSPC pool in NHD13 mice. (A) Representative flow plots gating for LSKs in the marrow of 5 female 20-week-old WT mice (concatenated data; left) and 5 female 20-week-old NHD13 mice (concatenated data; right). (B) Schematic of competitive repopulation assay. Whole BM from 4 22-week-old NHD13 or WT littermate donors was transplanted in a 1:1 ratio with normal WT whole BM into each of 2 lethally irradiated WT recipients. After harvesting primary recipient BM at 16 weeks posttransplant, 500 000 whole BM cells were transplanted into lethally irradiated secondary WT CD45.1 recipients. (C) Serial blood flow cytometric analysis was performed at 4-week intervals. Mice transplanted with NHD13 marrow (n = 8) had decreased donor-derived HSPC function compared with those transplanted with WT marrow (n = 7) as measured by percent of donor cells in the peripheral blood. Results analyzed for statistical significance using 2-way ANOVA with point matching; P < .01 for all parameters. Bonferroni posttests significant for all except CD11b curves. (D) Serial blood flow cytometric analysis in secondary transplant recipients. Primary donor NHD13 cells contributed proportionately less to circulating B and T cells in secondary recipients (P < .0001 by 2-way ANOVA with point matching) and more to circulating myeloid cells (P < .0001). (E) At 16 weeks post–primary transplant, percent lineage contribution to CD45.2 blood cells is shown from NHD13 (n = 7) and WT (n = 7). (F) Sixteen weeks post–secondary transplant, percent lineage contribution to CD45.2 blood cells is shown from NHD13 (n = 8) and WT (n = 7). (G) Donor contribution to LSK pool in the BM of primary recipients harvested 16 weeks posttransplant. Results analyzed for significance via Student t test. Each dot represents an individual mouse. ***P < .001.