SR-1–treated hESCs demonstrate increased multilineage hematopoietic development. (A) Bulk, nonadherent hematopoietic progenitor cells and (B) sorted CD34⁺CD45⁺ cells derived from hESCs differentiated in the presence of SR-1, TCDD, or DMSO controls were harvested at day 6+5 and seeded at 50 000 cells per dish in a standard methylcellulose CFU assay. Colonies were counted for each treatment group following 2 weeks of culture and scored for the following morphological subsets: burst-forming unit-erythroid (BFU-E); CFU-E; CFU–granulocyte, macrophage (CFU-GM); CFU–granulocyte, erythroid, macrophage, megakaryocyte (CFU-GEMM); CFU-M; n = 3, error bars represent SEM of the total number of colonies per 50 000 cells seeded. *P < .05, **P < .01 as assessed with 1-way analysis of variance (ANOVA) + Tukey-Kramer multiple comparisons post hoc test. (C) Representative BFU-E, CFU-E, CFU-GEMM, CFU-M, and CFU-GM as scored in panels A and B are shown. Scale bar, 100 μm. (D) Nonadherent hematopoietic progenitor cells derived from hESCs differentiated in the presence of SR-1, TCDD, or DMSO controls were harvested at day 6+3, day 6+6, and day 6+9 time points and probed for gene expression by qRT-PCR. For each gene, cycle threshold (C_t) values were normalized to GAPDH at each time point and data are presented as relative fold change to DMSO-treated controls; n = 3, error bars represent SEM; *P < .05, **P < .01 using the Student t test.