Warfarin impairs the HSC-supportive function of BM macrophages. (A) Number of cobblestones formed by 30 000 Lin⁻ cells under macrophages that had previously been treated with vehicle (red circles) or warfarin (blue squares) for 10 days (P = .02; t-test) (n = 6). The data were generated in 2 independent experiments. B) Percentage of total donor Actin DsRed⁺ leukocytes (P = .029; t test, n = 10) (B) and percentage of donor CD11b⁺ Actin DsRed⁺ myeloid cells (P = .023; t test, n = 6-8) (C) in recipients, which had been intrafemorally cotransplanted with 10⁵ untreated actin DsRed⁺ Lin⁻ and 5 × 10⁵ vehicle-pretreated (red circles) or warfarin-pretreated (blue squares) macrophages 6 to 8 weeks previously. The macrophages had, originally, been obtained from warfarin-treated mice and expanded in the continuous presence of warfarin in vitro. The data were generated in 2 independent experiments. (D) Total number of hematopoietic cells grown in CM harvested from MSCs (P = .009; ANOVA, Tukey test, n = 9) or macrophages (P = .04; ANOVA, Tukey test, n = 6) grown in vehicle-containing (red circles) or warfarin-containing (blue squares) medium 3 days after plating of 1 × 10⁶ Lin⁻ cells. The data were generated in 3 independent experiments.