The Role of BMP Signaling in the Expansion of Epiblast Stem Cell Plasticity
- Temple, Jasmine
- Advisor(s): Parast, Mana
Abstract
Bone morphogenetic protein (BMP) signaling has an established role in patterning of peri-implantation development in both mouse and human. In vitro, BMP4 has been shown to induce both primed and naïve human embryonic stem cells (hESCs) toward a trophectoderm (TE)-like cell, which can be further converted into trophoblast stem cells (TSC). However, the role of this signaling pathway in TE induction of hESC remains controversial, partly because of limitations in testing the functionality of these cells in human. In mouse, BMP4 treatment of ESC has been shown to induce some trophoblast- associated gene expression, but ESC conversion to TSC is not considered possible without genetic perturbation. Here we apply combined BMP4-IWP2 (Wnt inhibitor) treatment, a protocol used by the Parast Lab for TE induction of primed hESC, to mouse ESC-derived epiblast-like cells (mEpiLC), with subsequent adaptation to mouse TSC media. By immunostaining and single-cell RNA-sequencing, we show that trophoblast is one of the lineages induced and stabilized through this protocol. We further show that these mouse Trophoblast Stem Cell-Like Cells (mTSCLC) contribute to the extraembryonic compartments in both pre- and post-implantation ex vivo embryo models. We conclude that mouse post-implantation epiblast has the potential to be converted to the trophoblast lineage following activation of BMP signaling. In addition, multiple groups have used BMP4 for derivation of human TE and hTSC from primed hESC, but the true identity of these cells has been contested. In this study, we compare hESC, primary hTSC, hESC-derived TE, and hESC-derived hTSC to human amnion through single cell sequencing. We conclude that specific markers can distinguish between embryonic and extraembryonic ectoderm, and hESC-derived hTSC are bona fide human trophoblast cells.