PGE₂ increases homing efficiency of HSPCs. (A) Test murine bone marrow cells were labeled with CFSE and treated with vehicle (red) or dmPGE₂ (blue) and 2 × 10⁷ labeled and treated WBM cells were transplanted into lethally irradiated mice. Sixteen hours later, bone marrow was analyzed by FACS for homed events. Data are expressed as mean plus or minus SEM; n = 6 mice/group, each assayed individually. (B) Test bone marrow cells from CD45.1 mice were treated with PBS, vehicle, or dmPGE₂, and 2 × 10⁷ treated WBM cells were transplanted into lethally irradiated CD45.2 mice. Sixteen hours later bone marrow was analyzed for homed SKL cells. The left panel shows representative data from 1 experiment; n = 3 mice/group, each assayed individually. The right panel shows the combined increase in homing efficiency of SKL cells after dmPGE₂ treatment for 3 experiments (n = 6 mice/group per experiment, each assayed individually). (C) SKL cells from CD45.1 and CD45.2 mice were isolated by FACS sorting and treated with either dmPGE₂ or vehicle. Five lethally irradiated CD45.1/CD45.2 hybrid mice received 3 × 10⁴ vehicle-treated CD45.1-sorted SKL plus 3 × 10⁴ dmPGE₂-treated CD45.2 SKL cells (top panel). Five mice received a similar transplant with treatment groups switched between strains (bottom panel). Representative flow gating of marrow 16 hours after transplantation and combined data for the homing efficiency of dmPGE₂- or vehicle-treated, sorted SKL cells (mean ± SEM; n = 10 mice, each assayed individually) are shown. (D) Low-density UCB mononuclear cells (LDMCs) were isolated and treated with either dmPGE₂ or vehicle. Five sublethally irradiated NS2 mice received dmPGE₂-treated LDMCs and 5 received vehicle-treated LDMCs. Bone marrow was analyzed 16 hours later and the number of CD34⁺ cells determined and homing efficiency calculated. Data are mean plus or minus SEM for n = 5 mice, each assayed individually.