In vivo effects of LSD1 inhibition in SCD mice. (A) SCD mice were treated with GSK-LSD1, OG-L002, or LSD1-C12 at a concentration of 1 μg/g body weight per day, or LSD1-C76 (0.5 μg/g body weight per day), or S2101 (5 μg/g body weight per day) for 4 weeks. DMSO was injected as a negative control. Whole blood from SCD mice was stained with anti-human HbF antibody. Statistical analysis of the percentage of HbF-high cells (F cells) by flow cytometry averaged over all samples. Statistically significant differences between small chemical inhibitor-treated and control DMSO-treated SCD mice are indicated (*P < .05). Bar graph data are presented as the mean ± standard deviation, n = 3 mice per group. (B) The percentage of reticulocytes was measured by flow cytometry after thiazole orange staining of whole blood. The number shown above the horizontal bar in each box represents the mean fractional percentage of reticulocytes among the total cells in each group, n = 3 mice per group. (*P < .05 vs control DMSO-treated SCD mice). (C) Peripheral blood cells were stained with anti-mouse CD71 and Ter119 antibodies to assess the erythroid differentiation profiles of RBCs in chemical inhibitor–treated or control DMSO-treated SCD mice.²³  Stained cells were sorted into 3 stages (I, immature; II, maturing; III, mature). The numbers in each rectangle represent the mean fractional percentages of cells at that developmental stage in each group, n = 3 mice per group. (D) Wright-Giemsa staining (oxidized eosin Y, methylene blue, and azure B; original magnification ×40) of peripheral blood smears of SCD mice after 4 weeks of treatment.