Depletion of HMGB2 in primary immature progenitor cells impairs their erythroid and megakaryocytic potential. (A) Numbers of erythroid and megakaryocytic progenitors in the presence or absence of HMGB2. CD34⁺ cells were transduced with shControl or shHMGB2 lentiviruses and puromycin-resistant cells were plated in semisolid medium in methyl-cellulose to determine the number of BFU-Es, CFU-Es, and granulocyte-macrophage colony-forming units (CFU-GMs) or in Megacult collagen medium for megakaryocyte colony-forming units (CFU-MKs). Colonies were scored 12 to 14 days after plating. Morphology of a representative BFU-E generated by shControl-transduced or HMGB2-depleted cells was shown. (B) Immunophenotypic analysis of shControl- or shHMGB2-transduced cells. Puromycin-resistant cells were induced to differentiate and CD71 and GPA expression was analyzed by flow cytometry before (E0) and 2 (E2) or 5 (E5) days after induction of erythroid differentiation. (C-D) Cytology of the cells. Cytospin samples were prepared from shControl- or shHMGB2-transduced cells 5 days after induction of erythroid differentiation and stained with May-Grünwald-Giemsa. Different subpopulations of erythroblasts were characterized under the microscope and the proportion of each subpopulation was evaluated (C). These results are means of 3 experiments with different samples. One example of May-Grünwald Giemsa–stained cytospins of shControl- or shHMGB2-transduced cells using a Leica DXC950P microscope (40×) was shown (D).