Regenerative trophoblast models are largely in concordance with trophoblasts from peri-implantation human embryos while maintaining subtle differences
The mechanisms controlling trophoblast proliferation and differentiation during embryo implantation are fundamentally important in defining a successful pregnancy, yet poorly understood. Human trophoblast stem cells (TSC) and BMP4/A83-01/PD17034-treated pluripotent stem cell derived trophoblast cells (BAP) are two widely employed, contemporary models to study trophoblast development and function but how faithfully they mimic the identity of early stage trophoblast cells has not been fully examined. Here, we evaluate the transcriptomic profiles of trophoblast cells from these two widely used cell models and directly compare them with trophoblast cells from peri-implantation stage human embryos during extended embryo culture (EEC) between embryonic d 8 to d 12. Cells from BAP and TSC models all grouped closely with trophoblast cells from EEC, with the trophoblast sublineages, including cytotrophoblast (CTB), syncytiotrophoblast (STB), and extravillous-like migratory trophoblast (MTB), clustered together following dimensional analysis and unsupervised hierarchical clustering. However, subtle differences amongst models exist for each trophoblast sublineages. TSC-CTB is more similar to EEC-CTB from d 8 embryos with transcripts associated with increased Wnt signaling activities important for trophoblast stemness. BAP-CTB are more similar to EEC-CTB from d 10 and 12 embryos and upregulate transcripts important for trophoblast differentiation and invasion. For STB, EEC-STB showed enriched GO terms related to oxygen-dependent metabolism, while BAP and TSC-derived STB both prioritize lipid and membrane synthesis as well as actin reorganization and cell spreading. EEC-MTB transcripts indicate an increased level of invasiveness and motility compared to TSC-MTB with increased proliferative capacity. We also provide a pool of novel lineage markers in early trophoblast that were upregulated (>4-fold) across all three models and validate the presence of 11 proteins prominent in peri-implantation human embryos. Together, our comprehensive analysis revealed that both commonly used BAP and TSC models resemble features of peri-implantation trophoblasts, while still maintaining subtle transcriptomic differences in sublineages. Overall design: We collected human TSC and TSC derived STB and EVT, as well as hESC derived trophoblast cells (separated by cell size, <40um and >70um) by BAP treatment, then total RNA was extracted, followed by RNA-sequencing analysis.