Novel 3D in vitro models to evaluate trophoblast migration and invasion

Problem: Embryo implantation depends on the interactions between the developing embryo and the maternal endometrium. Signals originating from the decidua play a critical role in the process of implantation and trophoblast invasion; however, the molecular mechanisms mediating this interaction are poorly understood. The objective of this study was to develop in vitro models that would mimic the processes of attachment, migration, and early invasion of the trophoblast.

Methods of study: First trimester trophoblast cells (Sw.71 cells) were cultured in low attachment plates to form blastocyst-like spheroids (BLS). Epithelial-mesenchymal transition (EMT) characterization during BLS formation was determined by RT-PCR and Western Blot. The two 3D in vitro culture models consist of (a) trophoblast migration: BLS cultured in suspension (b) trophoblast invasion: human endometrium stromal cells (HESC) plated in the bottom of a 96-well plate, covered by Matrigel and BLS transferred on top. Matrigel was used to mimic the human endometrial extracellular matrix.

Results: Using 3D cell culture systems and real-time imaging, we are able to determine the impact of endometrial factors on trophoblast cell function. Endometrial stromal cells promote blastocyst-like spheroid migration of trophoblast cells and invasion of the extracellular matrix.

Conclusion: We report the characterization of 3D in vitro models to evaluate the interaction between endometrial cells and trophoblast during the process of migration and invasion. The models are useful tools in order to further study the molecular mechanism of embryo-maternal uterine cells interactions.