Differentiation of erythroblasts in culture dishes or a G-Rex bioreactor. (A) Erythroblast cultures were established in culture dishes. Erythroblasts were washed and reseeded at 1 × 106/mL in Cellquin medium supplemented with EPO (10 U/mL), Transferrin (700 μg/mL), 5% human plasma, and heparin (5 U/mL) (DM) in culture dishes (closed symbol) or G-Rex (open symbol). Erythroblasts were differentiated for 12 days. Cell density was measured at days indicated. Mean cell numbers were calculated. Error bars indicate SD Cell expansion was compared by 2-way analysis of variance; *P < .05, ***P < .001, ****P < .0001; n = 4. (B) Representative density plots indicate cell surface expression levels of CD71 and CD235 in cultures as described in panel A. Quadrants are labeled (P1-P4) and relative cell numbers per quadrant indicated as (C-D) percentage quantification of percentages per quadrant in dot blots similar to those shown in panel C. Error bars indicate SD (n = 4). (C) Cells cultured in dishes. (D) Cells cultured in G-Rex.