Defective hematopoiesis by RPS19^+/p.Q126X iPSCs. (A) Four-day-old EBs were disaggregated and analyzed by flow cytometry for CD31⁺/KDR⁺ cells, which represent prehematopoietic mesoderm. A representative experiment is shown on the left. The combined results of multiple experiments analyzing 3 WT control lines and RPS19^+/p.Q126X iPSCs are shown on the right. The black bars in the graph represent mean values. For iPSC lines examined in 3 or more independent experiments, the error bars show SD. For iPSC lines examined twice, individual data points from each experiment are shown as open squares. (B) Eight-day-old EBs were disaggregated and analyzed by flow cytometry for CD43⁺ cells, which represent the first hematopoietic progenitors to emerge from ESC or iPSC differentiation. A representative experiment is shown on the left. The combined results of 3 independent experiments are shown on the right. *P < .05. (C) Hematopoietic progenitor assay. EBs were dissociated at day 8 of differentiation and seeded into methylcellulose containing EPO, IL-3, SCF, and GM-CSF. CFU-GM and Ery colonies were enumerated 7 to 9 days after plating. *P < .05; NS (P = .17); n = 4 separate experiments, each in triplicate. CFU-GM, colony forming unit-granulocyte macrophage; NS, not significant.