Fig. 7

NO-induced CD34 expression has contrasting age-dependent effects on the HSC functionality. Lin⁻ cells isolated from juvenile mice (6–8 weeks; CD45.1) were treated or not with 200 μM sodium nitroprusside (SNP) for 3 days and infused into irradiated recipients (8–10 weeks; CD45.2); 7–8 mice were used per group. The level of engraftment was analyzed by flow cytometry analysis of peripheral blood (PB) and bone marrow (BM). Percentage chimerism by the donor cells in PB of recipients at 4 weeks (a) and 16 weeks (b) post-transplant is depicted. Percentage engraftment of total donor cells (c) and LSK CD34⁻ LT-HSCs (d) in the BM of recipients is illustrated. The engrafted donor cells were sorted from the bone marrow of primary recipients and infused into irradiated secondary recipients. The percentage chimerism by these primary engrafted donor cells was analyzed by flow cytometry in the PB of secondary recipients. Percentage chimerism produced by the primary engrafted cells in the PB of secondary recipients at 4 weeks (e) and 16 weeks (f) post-transplant is shown; 4–5 secondary recipients were used per group. Sort-purified LSK-CD34⁻ cells from juvenile (6–8 weeks) and adult (10–12 weeks) mice were treated with 200 μM SNP for 3 days (g) or 12 h (h), and the cells were subjected to qRT-PCR analyses. Relative expression of Cd34 and various transcription factors is illustrated (means ± SEM; N = 3). *p ≤ 0.05, **p ≤ 0.01, ***p ≤ 0.001, between control and SNP-treated sets; ^### p ≤ 0.001, SNP-treated juvenile versus SNP-treated adult HSCs. Also see Additional file 6 (Figure S4). NS not significant