Single-cell transcriptomics reveal differences between chorionic and basal plate cytotrophoblasts and trophoblast...

Area of Science:

• Reproductive biology
• Developmental biology
• Cellular and molecular biology

Background:

• Cytotrophoblast (CTB) cells in early human placenta are bipotent progenitors.
• These cells differentiate into invasive extravillous trophoblast (EVT) and syncytiotrophoblast (STB).
• Trophoblast stem cells (TSC) derived from early placentae are also bipotential.

Purpose of the Study:

• To investigate the transcriptional diversity of first-trimester CTB.
• To compare the transcriptional profiles of TSC with various CTB subgroups.
• To identify distinct trophoblast states and lineage biases.

Main Methods:

• Single-cell RNA sequencing of human placentae (6-14 weeks gestation) and TSC lines.
• Separation of placental tissues into basal and chorionic fractions.
• Differential gene expression analysis, clustering, and trajectory inference.
• Flow cytometry for marker analysis (ITGA2, ITGA5).

Main Results:

• CTB clusters showed distinctions based on gestational age and tissue origin (basal vs. chorionic).
• Basal plate CTB were enriched for EVT precursors, while chorionic plate CTB favored STB precursors.
• TSC were transcriptionally similar to EVT precursor cells, with limited STB differentiation potential.
• ITGA5+ CTB differentiated into EVT in 2D culture, while ITGA5- CTB formed organoids.

Conclusions:

• Distinct CTB states exist in different placental regions by six weeks gestation.
• Current TSC lines are biased towards the EVT lineage, resembling ITGA5+ CTB.
• Understanding trophoblast heterogeneity is crucial for early placental development research.