Characterisation of X chromosome status of human extended pluripotent stem cells.

Different pluripotent cell types have been established by capturing pluripotency in different states. Human extended pluripotent stem cells (hEPSCs), recently established by two independent studies, have the capability of differentiating into both embryonic and extraembryonic lineages, as well as forming human blastoids, showing great potential for early human development modeling and regenerative medicine. Considering that X chromosome status in female human pluripotent stem cells is dynamic and heterogeneous, and often leads to functional consequences, we characterized it in hEPSCs. We derived hEPSCs from primed human embryonic stem cells (hESCs) with defined X chromosome status (pre- or post-X chromosome inactivation) using two previously published methods. We showed that hEPSCs derived using both methods had highly similar transcription profiles and X chromosome status. However, the X chromosome status of hEPSCs is largely determined by the primed hESCs from which they were derived, suggesting a lack of complete reprogramming of X chromosome during primed to extended/expanded pluripotency conversion. Furthermore, we found that the X chromosome status of hEPSCs affected their ability to differentiate into embryonic or extraembryonic lineage cells. Taken together, our work characterized the X chromosome status of hEPSCs, providing important information for the future application of hEPSCs.