Changes in histone acetylation during in vitro differentiation of cord blood CD34⁺ progenitors. (Top) Scheme of in vitro differentiation. (A) Differentiation toward the erythroid lineage. Freshly isolated CD34⁺ cells (▭) were cultured in the presence of IL-3, IL-6, and stem cell factor; and after 7 days, CD36⁺ cells () were isolated and cultured for a further 5 days in the presence of Epo to give GpA⁺ cells (). (B) Differentiation toward the granulocyte lineage. Freshly isolated CD34⁺ cells (▭) were cultured in the presence of G-CSF, IL-3, stem cell factor, and Flt3-L for 14 days to give CD11b⁺ cells (). (C) Differentiation toward the T-lymphoid lineage. In vitro culture of CD34⁺CD38^lo cells (▭) was performed on OP9-hDelta1 stromal cells in the presence of Flt3-L, stem cell factor, and IL-7. After 21 days, more than 90% of cells were CD7⁺ committed T-cell precursors (). ChIP experiments were performed with antibodies to acetylated histones H3 and H4 at B-lymphoid (B), T-lymphoid (T), erythroid (E), myeloid (M), nonhematopoietic (N), and β2-microglobulin (B2m) genes. Representative results of 2 to 4 independent experiments are shown.