Fig. 4: Young HSCs support youthful hematopoietic characteristics upon transplantation into aged recipients.

a Experimental design. Aged (16 months) mice were treated with CD45-SAP (n = 8) or CD45-SAP with G-CSF/AMD3100 (n = 6) and transplanted with ex vivo expanded young HSCs (EE100 cells/mouse). b Young HSC-derived PB reconstitution in aged hosts 18 weeks after transplantation. c–d Absolute numbers of donor (c) and host (d) HSCs in aged recipients treated with CD45-SAP with or without G-CSF/AMD3100. In (d), HSC numbers in age-matched untreated controls were assessed for comparison (n = 5). In (b–d), gray, red, and dark gray circles represent CD45-SAP-, CD45-SAP/G-CSF/AMD3100-treated and untreated groups, respectively. e Chimerism levels in indicated hematopoietic cell subsets relative to the donor (young)- or host (aged)-derived HSCs in aged recipients (left, n = 10). Young recipients were used for comparison (right, n = 4). p value for each comparison is presented. Gray, red, and blue circles represent young donor, aged host, and young host groups, respectively. f Representative flow cytometric profiles of splenic B cell subsets within donor (young) and host (aged) cell fractions. ABC—age-associated B cells; MZ—marginal zone B cells; FO—follicular B cells. g Frequency of splenic ABC, MZ, and FO cells within donor (young)- and host (aged) CD19+ cell fractions (n = 10). h Representative flow cytometric profiles of splenic CD4 + T cell subsets within donor (young) and host (aged) cell fractions. CM—central memory; EM—effector memory. i Frequency of splenic naive, CM, and EM T cells within donor (young)- and host (aged) CD4+ (left) and CD8+ (right) cell fractions (n = 10). In (g) and (i), gray and red circles indicate donor (young) and host (aged) groups, respectively. In (b–e), (g), and (i), points indicate values for individual mice. In (b–d), error bars denote mean ± SEM. Statistical significance was determined by unpaired two-sided t test with Welch correction in (b–c) and (e), one-way ANOVA with a Tukey test in (d), two-sided Wilcoxon matched-pairs signed rank test in (g) and paired two-sided t test in (i). Source data are provided as a Source Data file.