Epithelial-mesenchymal transition during trophoblast differentiation

Area of Science:

• Reproductive biology
• Developmental biology
• Cell biology

Background:

• Embryo implantation is crucial for pregnancy success in higher primates.
• Trophoblast cells mediate early implantation phases, with syncytiotrophoblast and cytotrophoblast playing key roles.
• Three main trophoblast populations exist: stem cells, syncytiotrophoblast, and extravillous cytotrophoblast.

Purpose of the Study:

• To describe the differentiation and behavior of trophoblast populations during human placentation.
• To highlight the epithelial-mesenchymal transition (EMT) of extravillous cytotrophoblast.
• To emphasize the importance of EMT for successful pregnancy.

Main Methods:

• Observational study of trophoblast populations during placentation.
• Analysis of trophoblast cell differentiation and phenotype changes.
• Identification of molecular markers associated with extravillous cytotrophoblast EMT.

Main Results:

• Syncytiotrophoblast remains largely epithelial.
• Extravillous cytotrophoblast undergoes EMT, forming cell columns and invading maternal tissues.
• Infiltrating extravillous cytotrophoblast cells differentiate into placental bed giant cells.
• Extravillous cytotrophoblast phenotype changes, losing some epithelial markers (e.g., E-cadherin) but retaining others (e.g., cytokeratins).

Conclusions:

• Extravillous cytotrophoblast EMT is a critical process for deep placental invasion and successful pregnancy.
• Understanding the signals triggering EMT is essential for reproductive health.
• Trophoblast cell plasticity is key to establishing and maintaining pregnancy.