Human iPS-HPCs. (A) To determine the phenotype of iPS-HPCs, iPSCs cultivated on OP9 cells were harvested on differentiation day 9 and phenotypically characterized for various hematopoietic cell markers. iPS-HPCs expressed the hematopoietic cell surface markers CD34, CD43, CD45, and CD235a. We used the Tra-1-85 antibody to discriminate human cells. (B) The relative percentages of CD34⁺, CD43⁺, and CD45⁺ cells during the differentiation days 7, 9, and 12. (C) Five different human iPS cell lines were used to generate HPCs, respectively. The yield of CD43⁺/CD34⁺ HPCs was compared among these cell types. The data show that the efficiency of HPC derivation varied greatly among the iPSCs studied (mean ± standard deviation [SD]). ***P < .001. In particular, cell line 5 yielded the fewest number of CD34⁺ cells. (D) Total RNA was isolated from iPSCs, iPS-HPCs, and PBMCs enriched for CD34, respectively. RT-PCR of the hematopoietic-related genes HoxA9, Gata1, CD41, and CD45 was performed. β-Actin was used as a loading control. The results show that PBMC CD34⁺ cells and iPS-HPCs were identical in their gene expression patterns. (E) Microarray analysis of our 4 different iPS-HPC cell lines and UCB-CD34⁺ cells demonstrated that these cell lines have nearly identical hematopoietic gene expression profiles. These data suggest that the iPS-HPCs are similar to one another and confirm the authentic hematopoietic quality of these cells.