Pyrimido-indole derivative, um171 promotes differentiation and expansion of myeloid progenitors and nk cells from human pluripotent stem cells

Advances in hematopoietic differentiation from human pluripotent stem cells (hPSCs) open up new opportunities for the development of technologies for manufacturing patient-customized blood products. Scaling up production of blood cells from hPSCs would be the next step toward manufacturing and clinical translation of hPSC-based therapies for blood diseases. The pyrimidoindole derivative UM171 was recently identified as a chemical compound that can robustly expand hematopoietic stem cells (HSCs), including HSCs with long-term repopulation potential. Here we evaluated the effect of UM171 on CD43 hematopoietic progenitors (HPs) produced from hPSCs in vitro. hPSCs were differentiated for 9 days in chemically-defined 2D cultures, to induce the formation of CD43+ HPs. CD43+ HPs were then expanded in Serum Free Expansion Medium (SFEM), in the presence of SCF, TPO, FLT3, IL6, and IL3, and with UM171 (35 nM) or DMSO (control), and assayed for phenotype and colony forming cell (CFC) potential. We found that UM171 treatment resulted in a significant increase in the frequency and number of total and myeloid biased CD34+CD43+ HPs, and a significant increase in myeloid CFC number relative to DMSO, after up to 7 days of expansion. Interestingly, UM171 treatment resulted in the maintenance and expansion of an intermediate CD45+235a+/-41alo42b- population with significant myeloid (CFC-GM and CFC-G) potential. In contrast, DMSO expanded cells showed enrichment of a 235a+/-41ahi population that was positive for expression of the mature megakaryocytic lineage marker, CD42b, and had no CFC potential, suggesting megakaryocytic lineage restriction. In addition, we found that UM171 significantly and robustly enhances CD56+ NK cell generation from hPSC-derived CD43+ cells. Overall, our studies revealed that UM171 promotes the expansion of myeloid and NK cell progenitors from hPSCs. Delineating the molecular, cellular, and functional mechanisms behind these effects will be critical in elucidating the clinical applications of this molecule. and in gaining new insight into hematopoietic progenitor cell biology, particularly expansion, lineage commitment, and differentiation.