Enhancement of Arterial Specification in Human Pluripotent Stem Cell Cultures Promotes Definitive Hematoendothelial Program with Broad Myelolymphoid Potential

Identification of the regulators that lead to arterial specification with definitive hematopoietic potential should help to design strategies to recapitulate HSC development from human pluripotent stem cells (hPSCs). Here, using ETS1 conditional H1 hESC line, we found that ETS1 induction at the mesodermal stage of differentiation dramatically enhances the arterial specification in hPSC cultures and formation of DLL4+CXCR4+/- arterial HE with lymphoid potential and the capacity to produce red blood cells with high expression of BCL11a and b-globin. ETS1 effect was mediated through upregulation of NOTCH signaling. Together, these findings demonstrated that promotion of arterial specification in cultures could aid in generation of definitive hematopoiesis from hPSCs. We engineered H1 human embryonic stem cells (hESC) carrying doxycycline (DOX)-inducible ETS1-P2A-EGFP transgene (iETS1-hESCs) and differentiated them to endothelial and hematopoietic cells in chemically defined conditions