UM171 enhances the efficiency of gene transfer into CD34⁺ from patients with SCD and reduces manufacturing stress in vitro. (A) Lentiviral VCN in CD34⁺ cells transduced with LV-BCL11A in the presence or absence of UM171 was measured by quantitative PCR. (B) DNA damage was assessed by the level of γH2AX staining. (C) Assessment of the level of ROS⁺ cells, (D) cell cycle, and (E) the percentage of Annexin V⁺ cells after transduction in the presence or absence of UM171. Readouts after 7 days in culture. Data represent mean ± SD, n = 3, 3 independent experiments from cells of different patients with SCD. ∗P < .05; ∗∗P < .01; ∗∗∗∗P < .0001.