Large-scale production of erythroid cells from hESCs. (A) Erythroid cells (pellet) derived from 2 × 106 human ESCs. (B) Erythroid cells from panel A were resuspended in equivalent hematocrit of human whole blood. (C,D) Morphology of erythroid cells derived from human ESCs (C: original magnification ×200; D: original magnification ×1000). (E) Electrospray ionization mass spectra of globin chains in hemoglobins from hESC-derived erythroid cells, confirming the presence of α, ζ, ϵ, and γ globins. The observed molecular weight for each of the globins is shown. (F) Flow cytometric analysis of hESC-derived erythroid cells. Erythroid cells derived from hESCs were labeled with specific antibodies conjugated with phycoerythrin and analyzed on a FacScan flow cytometer (BD Biosciences) with the CellQuest program. Corresponding unspecific isotype antibodies conjugated with the same dyes were used as negative controls.