Rapid response of HSCs from Thpo^fl/fl;AlbCre^+/− mice to romiplostim. Romiplostim was administered IV to Thpo^+/+, Thpo^fl/fl;AlbCre^+/−, and Thpo^−/− mice for 5 consecutive days. (A) PB platelet count in Thpo^+/+, Thpo^fl/fl;AlbCre^+/− and Thpo^−/− mice treated with romiplostim (Thpo^+/+ Ro, Thpo^fl/fl;AlbCre^+/− Ro, and Thpo^−/− Ro) (n = 5). (B) BM HSC number in Thpo^+/+, Thpo^+/+ Ro, Thpo^fl/fl;AlbCre^+/− Ro, and Thpo^−/− Ro mice (n = 5). (C) Representative flow cytometric plot and percentage of G₀, G₁, and S/G₂/M HSCs in Thpo^+/+ Ro, Thpo^fl/fl;AlbCre^+/− Ro, and Thpo^−/− Ro mice (n = 5). (D) Percentage of subG₁ HSCs in Thpo^+/+ Ro, Thpo^fl/fl;AlbCre^+/− Ro, and Thpo^−/− Ro mice (n = 5). Mean fluorescence intensity (MFI) of tetramethylrhodamine, ethyl ester staining (TMRE) (E) and CellROX staining (F) in Thpo^+/+,Thpo^+/+ Ro, Thpo^fl/fl;AlbCre^+/− Ro, and Thpo^−/− Ro mice (n = 5). *P < .05, **P < .01, ***P < .001. Student t test (A-B,D-F), Fisher’s least significant difference test (C).