Figure 2.

SSA Enhances the Functional Repopulation Potential of HSCs Derived from Middle-Aged Mice

(A–C) CD45.1 BM cells were harvested and pooled from 9-month d7shSSA, (n = 5 recipients/donor group) or 9-month d7SSA (n = 5 recipients/donor group) and 2.5 × 10⁶ cells were transferred with an equal dose of untreated 2-month CD45.2 BM cells into lethally irradiated 2-month CD45.2 recipients. Reconstitution was analyzed at the designated time points. (A) Concatenated donor (CD45.1) versus competitor (CD45.2) flow cytometry profiles of spleen 17 weeks after transplant. (B) Total peripheral reconstitution measured by CD45.1 in spleen or peripheral blood over 120 days. (C) Lineage-specific reconstitution of B220⁺ B cells, TCRβ⁺ T cells, Gr1+CD11b⁺ granulocytes, and Gr1^loCD11b⁺ monocyte/macrophages in the spleen at 28 and 120 days after transplant.

(D–G) 2,000 FACS purified CD45.1 LSK cells from untreated 2-month; 9-month d7shSSA; or 9-month d7SSA were transferred along with 2 × 10⁶ BM cells from untreated 2-month CD45.2 competitors into lethally irradiated CD45.2 recipients (n = 5–7/donor group). (D) Total number of CD45.1 donor-derived cells in the BM of recipients 28 days after transplant. (E) Proportion of CD45.1⁺ whole BM, LSK, CLP, and MCP cells in the BM 28 days after transplant. (F) Concatenated donor (CD45.1) versus competitor (CD45.2) flow cytometry profiles of spleen 19 weeks after transplant. (G) Peripheral reconstitution in 28, 70, and 135 days after transplant. ^∗Compared with 9-month shSS A mice. ˆCompared with untreated 2-month mice.

(H) Lineage repopulation was measured among B220⁺ B cells, TCRβ⁺ T cells, Gr1⁺CD11b⁺ granulocytes, and Gr1^loCD11b⁺ monocyte/macrophages.

Results are expressed as mean ± SEM. ^∗/ˆp < 0.05, ^∗∗/ˆˆp < 0.01, ^∗∗∗/ˆˆˆp < 0.001. See also Figure S2.