IMiDs do not inhibit maturation or endomitosis of megakaryocytes. (A) Cytospin preparations of cells derived from CD34⁺ HSPCs (May-Giemsa staining) showing large and weakly basophilic cytoplasm, azurophilic granules, and multilobulated nuclei. HSPCs were cultured in serum-free liquid media for 10 days in the presence or absence of 10 µM of IMiDs. Images were captured by a BH-2 microscope (Olympus) and ACT-2U imaging software (Nikon) with ×600 magnification (scale bars, 25 µm). (B) Flow cytometric analysis of CD41 and CD42b expression. Representative flow cytometric plots are shown in 3 panels on the left. Summarized data of the percentages of CD41⁺CD42b⁺ phenotypically mature megakaryocytes are shown in the right panel. (C) DNA ploidy analysis by flow cytometry. Ploidy levels were evaluated based on the DNA content with PI staining. Representative ploidy histograms are shown in 2 panels on the left. Summary of the ploidy distributions is illustrated in the right panel. Data are from 4 (B) and 3 (C) independent experiments and expressed as means ± standard errors of the mean. P values were determined by 2-tailed Student t test. Cont, control; Len, lenalidomide; Pom, pomalidomide.