Augmentation of HbF and total Hb content in β-thalassemic erythroblasts derived from CD34⁺ cotransduced with both the V5m3-400 γ-globin and GG1-VP64/GFP lentiviral vectors. (A) Histograms of flow cytometric analysis of erythroblasts derived from CD34⁺ cells treated as indicated. Analysis for both GFP and CD235 at the end of the culture. (B) The percentages of CFU transduced with the GFP control or GG1-VP64/GFP vectors, as judged by GFP positivity by fluorescence microscopy, are indicated by the top of the bar (gray). The percentage of GFP⁺ CFU that contain the V5m3-400 vector by DNA PCR is indicated by the black portion of the bar. (C) Cellulose acetate Hb electrophoresis of lysates from erythroblasts derived from CD34⁺ BM cells of a β-thalassemic donor cotransduced with the indicated vectors. Percentages below each lane represent the amount of HbF, relative to total Hb, as determined by HPLC. Vertical lines have been inserted to represent repositioned lanes on the gel images. (D) The percentage of total Hb content, relative to that of erythroblasts derived from normal PB CD34⁺ cells, of β-thalassemic erythroblasts derived from the indicated transduced cell populations. PB CD34 indicates erythroblasts derived from cytokine-mobilized peripheral blood CD34⁺ cells of normal donors; and CB CD34, erythroblasts derived from CD34⁺ cord blood cells.