Description
Human pluripotent stem cells (hPSC) exposed to BMP4 (B) and inhibitors of ACTIVIN signaling (A83-01; A) and FGF2 (PD173074; P) in absence of FGF2 (BAP conditions) differentiate into colonies primarily comprised of trophoblast. In an attempt to isolate trophoblast stem cells, colonies of hESC were exposed to BAP for 24 h at which time they had begun to transition into a CDX2-positive state. Cultures were then dissociated into single cells by trypsin and grown on a gelatin substratum. Under these conditions, organized CDX2+/KRT7- colonies began to emerge within a few days. The self-renewing cell lines were not TBSC, but met standard criteria for pluripotency. They were named H1BP cells. They differed from the progenitor hPSC in morphology, ability to be clonally propagated from single cells onto gelatin, requirements for FGF2, and transcriptome profile.