D₂-type dopamine receptors regulate BM transplantation efficiency. (A) Diagram depicting the transplantation of WT or Drd-DKO LSK cells into lethally irradiated WT mice. (B) Pseudocolor FACS plot of CD45⁺ leukocytes in recipient BM, analyzed 14 days after transplantation. Numbers in rectangles represent the percentages of gated cells. (C) Quantification of BMNCs, LSK cells, and CD45⁺ cells (WT = 11; Drd-DKO^ΔHC = 13). The P value was calculated using the Student t test. (D) Confocal image of Ki67 staining in bone sections from recipients transplanted with WT or Drd-DKO cells (left panels). Quantification of Ki67⁺ cell number in each image field (right panel; WT = 6; Drd-DKO^ΔHC = 6). The P value was calculated using the Student t test. (E) Diagram depicting transplantation of LSK cells from WT mice into lethally irradiated WT or Drd-DKO recipients. (F) Representative FACS plot of CD45⁺ leukocytes in WT or Drd-DKO^ΔSC. Numbers in boxed areas represent the percentage of cells in the BM. (G) Quantification of BMNC and CD45⁺ cell number in WT (n = 8) or Drd-DKO^ΔSC (n = 9) recipients. The P value was calculated using the Student t test. (H) Scheme illustrating the lethal irradiation (12 Gy) of DTR^iΔTh and littermate controls and transplantation of genetically labeled (GFP⁺) Lin⁻ HSPCs from Vav1-Cre Rosa26-mTmG donors (day 0) and treatment with DTX on days 0 and 1. Following EdU injection at day 4, mice were euthanized 1 hour later for immunostaining and FACS analysis. (I) Overview of bone sections from DTR^iΔTh or littermate control mice after lethal irradiation and transplantation of GFP-labeled donor cells. Green, donor-derived hematopoietic cells; red, EdU; blue, Emcn. (J) Representative confocal images of bone sections showing GFP⁺ cells (green), Emcn⁺ endothelial cells (blue), and EdU incorporation (red) in DTR^iΔTh (lower panels) or littermate control (upper panels) mice. (K) Percentage of donor-derived GFP⁺ and GFP⁺ CD45⁺ cells by FACS (Ctrl = 6; DTR^iΔTh = 6). Quantification of EdU⁺ cells in each field by imaging (Ctrl = 5; DTR^iΔTh = 5). The P value was calculated using the Student t test. 1h, 1 hour; 12Gy4D, 4 days after lethal irradiation at 12Gy; Ctrl, control; D, day; SSC, side scatter.