FIG. 2.

Expansion profiles of individual erythroid cultures from hESCs (A), transgenic (B), and transgene-free iPSCs (C). The cell expansion number at each time point is calculated as a total number of cells generated per 1 hESC/hiPSC induced to differentiate in coculture with OP9. Day 0 indicates the day when erythroid cultures were initiated from OP9 differentiated hESC/hiPSCs. E1–E3 refers to individual experiments. CD31 and CD34 indicate experiments in which erythroid cells were generated using Method A by isolating corresponding cell population. Nonseparated (NS) erythroid cells generated using Method B without isolation of progenitors (NS cells). Erythroid cultures from transgene-free iPSCs depicted in (C) were terminated at day 37. (D). Red blood cell pellet (6×10⁸ cells) derived from 10⁵ hESCs using Method A after 30 days expansion. (E) Flow cytometric analysis of cells shown in (D) demonstrates that these CD235a⁺ erythroid cells are essentially free of CD45⁺ leukocytes.