The feeder-free, chemically defined production of HPs from iPSCs produces populations of cells that express markers of both the megakaryocyte and erythroid lineages. (A) Differentiation strategy from iPSC to HP stage. Phase-contrast images (10×) of cultures depicting morphologic changes and the production of both an initial adherent layer followed by nonadherent HPs. (B) Representative fluorescence-activated cell sorter (FACS) analysis of day 15 HPs that coexpress CD235 (red cells) and CD41 (megakaryocytes). (C) Quantitative PCR analysis of undifferentiated iPSCs vs day 15 HPs. Relative gene expression was normalized to β-actin. Data are the average of 3 independent experiments ± SD: *P < .05. (D) Representative FACS analysis of day 15 HPs that have been exposed to either erythroid- or megakaryocyte-specific specification media for 5 days.