Early hematopoietic reconstitution kinetics of BM cells selected pretransplantation on the basis of marrow or splenic homing. Lethally irradiated mice were injected with 108PKH26-stained syngeneic BM cells. Three hours later, PKH26+ cells that had homed to the marrow (○) or spleen (•) were isolated by FACS and transplanted into lethally irradiated Ly-5 congenic mice (106 cells/mouse). Control animals were injected with 106 PKH26-stained BM cells that had not been selected by a prior homing step (□). Peripheral blood leukocytes (A), erythrocytes (B), and platelets (C) were counted on the indicated days. The normal range of blood cell counts (except leukocytes, which are off scale) and their decline after irradiation are defined by the shaded areas and thick gray lines. Shown are the mean ± SEM values for pooled data from 3 experiments (5 to 14 mice/population). Errors not shown are too small for the scale used. Differences in leukocyte counts in recipients of BM-homed or SPL-homed cells are significant on days 25 and 32 (P < .05).
