Identification and single cell functional characterization of an endodermally-biased pluripotent sub-state in human embryonic stem cells

Human embryonic stem cells (hESC) display substantial heterogeneity in gene expression, implying the existence of discrete substates within the stem cell compartment. To determine whether these substates impact fate decisions of hESC we used a GFP reporter line to investigate the properties of fractions of putative undifferentiated cells defined by their differential expression of the endoderm transcription factor, GATA6, together with the hESC surface marker, SSEA3. By single cell cloning, we confirmed that substates characterized by expression of GATA6 and SSEA3 include pluripotent stem cells capable of long term self-renewal. When clonal stem cell colonies were formed from GATA6-positive and GATA6-negative cells, more of those derived from GATA6-positive cells contained spontaneously differentiated endoderm cells than similar colonies derived from the GATA6-negative cells. We characterized these discrete cellular states using single cell transcriptomic analysis, identifying a potential role for SOX17 in the establishment of the endoderm biased stem cell state. Examination of 4 different cell substates within one human embryonic stem cell line as determine by the expression status of GATA6 and SSEA3