Aged mice mobilize a higher number of HSCs to PB in response to G-CSF. (A) Experimental setup of competitive transplantation of mobilized PB cells. (B) Flow cytometric analysis of chimerism in PB of mice that underwent competitive (50/50) transplantation with mPB from aged (Ly5.2+) and young (Ly5.1+) mice 5 months after transplantation. (C) Determination of the percentages of T, B, and myeloid (MY) cells in PB cells derived from the transplanted mobilized HSCs from aged mice in the recipient 5 months after transplantation by flow cytometry. Data are a summary of 2 independent experiments; in each, n = 3 for the number of donors per age group from which PB was collected and n = 4 for the number of recipients. One recipient animal had graft failure and was excluded from the analysis. Values shown are mean ± 1 SEM. *P < .05.