Low O₂ selective HSC cultures help avoid GVHD. (A) Schematic diagram of allogeneic transplantation assay. Unfractionated WBMCs and/or spleen cells from C57BL/6 mice were transplanted into irradiated Balb/c mice before or after 4-week PVA-based culture. (B) Survival of Balb/c recipients in the assay described in panel B, after transplantation of 5 × 10⁶ WBMCs and 5 × 10⁶ whole spleen cells (fresh or cultured) from C57BL/6 mice (n = 7-8). Statistical analysis was performed using the Mantel-Cox test. (C) Survival of Balb/c recipients in the assay described in panel B, after the transplantation of 5 × 10⁶ whole spleen cells (fresh or cultured) from C57BL/6 mice (n = 7-8). Statistical analysis was performed using Mantel-Cox test. (D) Schematic diagram of antibody conditioning transplantation assay. Four-week cultured WBMCs (derived from 20 × 10⁶ WBMCs), 4-week cultured HSCs (derived from 500 HSCs), or 5000 fresh HSCs from C57BL/6-CD45.1 mice were transplanted into Fancd2^–/–-CD45.2 mice 7 days after treatment with the anti-CD4 (GK1.5) antibody. (E) Donor chimerism in the Fancd2^–/– recipient mice at 4 or 20 weeks with peripheral blood Mac1⁺Gr1⁺ myeloid cells (top left), B220⁺ B cells (top right), CD4⁺CD3⁺ T cells (bottom left), and CD8⁺CD3⁺ T cells (bottom right) (n = 4). (F) Donor chimerism in the Fancd2^–/– bone marrow and peripheral blood compartments of recipients described in panel F (n = 4). ∗∗∗∗P < .0001.