(A) mRNA expression levels of the Wnt pathway–related genes TCF7, LEF1, and FZD3 in FACS-isolated HPCs from young (Y, n = 7) or old (O, n = 10) subjects. (B) mRNA expression levels of the mTOR pathway–related genes mTOR and S6K in FACS-isolated HPCs from young (n = 6) or old (n = 10) subjects. (C) Representative staining and median fluorescence intensity (MFI) levels for phosphorylated S6K in bead-enriched CD34+ cells from young or old adult PBMCs. (D and E) Representative staining and MFI levels of MitoTracker (mitochondrial mass marker) and CellRox (cellular ROS marker) in bead-enriched CD34+ cells from young or old adult PBMCs. (F and G) mRNA expression levels of genes associated with mitochondrial protein folding stress (CLPP, CLPX, and LON) and mitochondrial stress response (HSP60, HSP70) in FACS-isolated HPCs from young (n = 6) or old (n = 9) subjects. (H) Frequency of young or old CD34+ cells expressing the nuclear antigen Ki67. (I) Representative staining for Ki67 in CD3+ or CD34+ cells from an elderly individual, highlighting differential Ki67 expression levels. The Mann-Whitney test was used for comparisons. Bars indicate the median.