PGE₂ enhances hematopoietic stem cell engraftment. (A) Test bone marrow from CD45.1 or CD45.2 mice was treated with vehicle or dmPGE₂, respectively. CD45.1/CD45.2 hybrid marrow cells were used as competitors. Limiting dilutions were transplanted into lethally irradiated (1100 cGy, split dose) CD45.1/CD45.2 hybrid mice and chimerism in PB was analyzed for 20 weeks. A representative flow plot detecting each cell population is shown. (B) Frequency analysis (top) for vehicle (red)– or dmPGE₂ (blue)–pulsed cells, determined by Poisson statistics, at 12 weeks; P₀ = 85 560 (vehicle) and P₀ = 23 911 (dmPGE₂ treated). Chimerism in PB and CRU analysis is shown at 12 weeks (mean ± SEM). Data represent 2 pooled experiments; n = 5 mice/group/experiment, each assayed individually. (*P < .05 compared with vehicle control.) (C) HSC frequency analysis in recipients of vehicle- or dmPGE₂-treated bone marrow over 20 weeks. Fold change indicates increase in frequency of engraftment of dmPGE₂-pulsed cells compared with vehicle. (D) Representative FACS plots of multilineage reconstitution (M indicates myeloid; B, B lymphoid; and T, T lymphoid). Multilineage analysis for primary transplantation (32 weeks) and a cohort of 4 mice that received transplants from mice that underwent primary transplantation at 20 weeks, with analysis 12 weeks later. For mice that underwent primary transplantation at 32 weeks, vehicle-treated cells were (mean ± SEM) 14.1% plus or minus 3.5% M, 70.8% plus or minus 1.1% B, and 17.8% plus or minus 1.4% T, versus dmPGE₂-treated cells, which were 15.7% plus or minus 2.5% M, 76.9% plus or minus 3.4% B, and 7.5% plus or minus 1.2% T. For mice that underwent secondary transplantation at 12 weeks, vehicle-treated cells were 15.7% plus or minus 5.3% M, 60.3% plus or minus 4.8% B, and 22.1% plus or minus 3.6% T, versus dmPGE₂-treated cells, which were 37.0% plus or minus 6.5% M, 52.3% plus or minus 5.4% B, and 9.0% plus or minus 1.4% T. (*P < .05 vs vehicle control.) Increased chimerism of dmPGE₂-treated cells versus vehicle is shown for primary transplantation at 20 weeks (time of secondary transplantation) and in a subcohort at 32 weeks (time of 12-week analysis of secondary transplantation), for secondary transplantation at 12 weeks and 24 weeks. Data for 20-week primary transplantation were from 2 pooled experiments; n = 5 mice/group/experiment, each assayed individually. Data for secondary transplantations were from n = 5 mice/group, each assayed individually.