Aged Gata2^+/− and vav-cre;Gata2^fl/+ mice exhibit diminished HSC functionality together with significant defects when subjected to proliferative stress. (A) Representative example of the developmental stage and genotype of the mice used in the study. % of HSCs in both WT (red) and Gata2^+/− (blue) from embryo (E14) (B), adult (8-25 weeks) (C), and aged (15 months) (D) mice. Representative example of the developmental stage and genotype of the mice used in the study (E). Number of stem and progenitor cells in adult (F) Gata2^fl/+ (gray) and vav-Cre;Gata2^fl/+ (brown) and aged mice (G). Blood cell count of Gata2^fl/+ and vav-Cre;Gata2^fl/+ over the time (H). Histopathology performed on sternum from aged Gata2^fl/+ and vav-Cre;Gata2^fl/+ mice (I). Adult HSC cells from both Gata2^fl/+ and vav-Cre;Gata2^fl/+ adult mice were serially cultured in CFU (J, first plate; K, re-plating). ∗P < .05; ∗∗∗P < .001. BFU-E, burst-forming unit erythroid; CFU, colony-forming unit assays; G, granulocyte precursor cell; GMEM, granulocyte, monocyte, erythrocyte, and megakaryocyte; GM, granulocyte-macrophage progenitor; H&E, hematoxylin and eosin; HPC, hematopoietic progenitor cell; M, monocytic precursor cells; MPO, myeloperoxidase staining; MPP, multi-potent progenitor.