Sdc2⁺ HSCs display increased quiescence and proliferative capacity. (A) At left, representative flow cytometric analysis of CD150⁺CD48^– cells within BM 34^–KSL cells (HSCs), Sdc2^– HSCs, and Sdc2⁺ HSCs; at right, percentages of CD48^–, CD150⁺, and CD150⁺CD48^– cells in each population are shown (n = 8 mice per group). (B) At left, α-catulin ^GFP expression in 34^–KSL cells (HSCs), Sdc2^– HSCs, and Sdc2⁺ HSCs; at right, percentages of ɑ-catulin⁺ cells in each population (n = 6 mice per group). (C) At left, Flt3 expression in 34^–KSL cells (HSCs), Sdc2^– HSCs, and Sdc2⁺ HSCs; at right, percentages of Flt3^– cells in each population (n = 8 mice per group). (D) At left, representative flow cytometric analysis showing percentages of 34^–KSL cells (HSCs), Sdc2^– HSCs, and Sdc2⁺ HSCs in G₀, G₁, and G₂/S/M phases; at right, percentages of cells in G₀, G₁, and G₂/S/M phases (n = 3 mice per group). (E) Experimental design for primary competitive repopulation assay of Sdc2⁺ HSCs, Sdc2^– HSCs, and HSCs from CD45.1⁺ mice into CD45.2⁺ recipients for cell cycle analysis. (F) Representative flow cytometric analysis showing percentages of 34^–KSL cells (HSCs), Sdc2^– HSCs, and Sdc2⁺ HSCs in G₀, G₁, and G₂/S/M phases at 8 weeks posttransplant. (G) Quantification of the percentage of donor cells within each cell cycle phase (n = 7-10 mice per group). (H) Quantification of the percent donor 34^–KSL HSCs in G₀ relative to BM cells (n = 7-10 mice per group). Error bars = standard error of the mean; statistics denote Holm-Šidák’s post hoc unpaired Student t test following one-way ANOVA; *P < .05, **P < .01, ***P < .001, ****P < .0001. ns, not significant; SSC-A, side scatter area; WBM, whole BM.