Increased, low-ploidy megakaryocytes develop from Rbm15-KO HSC/Ps. (A-B) Liquid culture of lin⁻ marrow cells. Lin⁻ cells isolated by magnetic-activated cell sorting were cultured in hematopoietic stem cell expansion media for 2 to 3 days, and then allowed to differentiate toward the megakaryocytic lineage, as described.²¹  (A, top panel) Representative flow analysis of the CD41 surface marker specific for megakaryocytes of the cells after a 4-day induction. (Bottom panel) Average percentages of CD41⁺ cells from 3 independent experiments are graphed. Error bars show SD. (B) The differentiated megakaryocytes were cytospun onto slides and stained for AchE. AchE-positive megakaryocytes are darkly stained brown. The original magnification was ×100. (C) Ploidy analysis of in vitro cultured megakaryocytes. Ploidy of CD41⁺ cells from liquid-cultured Lin⁻ cells from Rbm15-KO mice and WT littermates was analyzed by flow cytometry using PI to determine DNA content. The percentages of cells of different ploidy status are shown in the table below. Data from 2 representative experiments using Rbm15-KO cells are shown.