Wt1 haploinsufficiency induces age-dependent changes in hematopoietic stem cell function. (A) Schematic model used to study effect of Wt1 depletion on hematopoiesis among aging. Control, Wt1^fl/+, and Wt1^fl/fl mice were injected with poly(I:C) at 1 month of age (young) or at 6-8 months of age (old), followed by detailed hematopoietic assessment at early (acute) and late (chronic) time points. (B) Proportion of recipient cells (CD45.1⁺) or donor cells (CD45.2⁺) in the BM compartment of control, Wt1^fl/+, and Wt1^fl/fl animals from young chronic, young acute, and old acute cohorts (n = 5). (C) Methylcellulose assays on total BM cells from control or Wt1^fl/+ mice from young chronic, young acute, and old acute subgroups (n = 5 independent experiments per arm, in triplicate). (D) WBC counts of control, Wt1^fl/+, and Wt1^fl/fl animals from secondary recipients transplanted with total BM cells of each genotype from the young chronic cohort (n = 5). (E) Quantification of progenitor cells among donor cells (CD45.2⁺) in the BM compartment of secondary recipient mice transplanted with control, Wt1^fl/+, or Wt1^fl/fl cells from the young chronic subgroup (n = 5). Data are mean ± standard error of the mean (B-E). *P < .05, **P < .01, ***P < .001, ****P < .0001, 2-way analysis of variance.