Accelerated progression of NHD13 MDS in Spp1-KO microenvironment. (A) A mix of NHD13^STEM:WT^CD45.2.STEM BM cells were transplanted in lethally irradiated CD45.2 WT (n = 10) or Spp1-KO (n = 9) mice at a ratio of 3:1. Mice were tracked via monthly peripheral blood analysis. (B-C) Chimerism analysis demonstrating a competitive advantage of WT over NHD13 donor cells in PB in both WT and Spp1-KO recipients. (D) Higher chimerism of NHD13 donor cells in Spp1-KO than in WT recipients. (E) Higher chimerism of WT donor cells in WT than in Spp1-KO recipients. (F) Higher contribution of NHD13 donor cells to peripheral blood myeloid compartment in Spp1-KO recipients. (G) Higher contribution of WT donor cells to peripheral blood myeloid compartment in WT recipients. (H) Very low contribution of NHD13 cells to donor CD3⁺ cells in WT and Spp1-KO recipients. (I) Competitor WT cells are a major source of donor derived CD3⁺ cells in WT and Spp1-KO recipients. (J) Very low contribution of NHD13 cells to donor B220⁺ cells in WT and Spp1-KO recipients. (K) Competitor WT cells are a major source of donor-derived B220⁺ cells in WT and Spp1-KO recipients. (L) Peripheral blood RBC count, (M) hemoglobin, and (N) mean corpuscular volume (MCV). (O) Survival analysis of WT and Spp1-KO animals that received NHD13 transplant. Data in panels B-N are presented as mean ± SD; ∗P < .05; ∗∗P < .01. Statistical significance was calculated using 2-way analysis of variance; multiple comparisons were corrected for using original FDR method of Benjamini and Hochberg.