Interaction of human trophoblast cells with gland-like endometrial spheroids: a model system for trophoblast invasion

participants/materials,setting,methods: Three human adenocarcinoma EEC lines were chosen for this study because of their differences in differentiation and polarization: HEC-1-A, which is well differentiated and highly polarized, Ishikawa, which is well differentiated and moderately polarized, and RL95-2, which is moderately differentiated and poorly polarized. When the cell lines were grown in reconstituted basement membrane, they formed gland-like, multicellular spheroids. The degree of polarization within the different EEC spheroids was assessed by 3D confocal immunofluorescence microscopy detecting the basal membrane protein integrin a6, the apical tight junction-associated protein ZO-1 and the desmosomal plaque protein desmoplakin 1/2 (Dsp). Cells of the human EVT cell line AC-1M88, which is a fusion cell line of primary EVT cells and choriocarcinoma-derived JEG-3 cells, were added to the different EEC spheroids to examine their interaction. For the analyses of trophoblast-endometrial confrontation sites, HLA-G was used as a specific EVT cell marker. main results and the role of chance: The endometrial HEC-1-A and Ishikawa cells formed gland-like structures in reconstituted basement membrane with apicobasal polarization towards their well-developed internal lumina, while most of the RL95-2 spheroids showed no lumen formation at all. The three EEC lines strongly differed in their apicobasal distribution pattern of Dsp. Ishikawa and HEC-1-A spheroids showed a subapical concentration of Dsp. In contrast, an equal distribution of Dsp was discerned along the entire lateral membranes in RL95-2 spheroids. In 3D confrontation co-cultures the highest invasiveness of AC-1M88 was observed in the poorly polarized RL95-2 spheroids. limitations,reasonsforcaution: Human endometrial and trophoblast cell lines were used for this study because of ethical and legal restrictions for implantation studies with human blastocysts and because of limited access to primary human endometrial cells. wider implications of the findings: The presented 3D cell culture system can be used to investigate the contribution of epithelial junctions to trophoblast-endometrial interactions. The identified impact of endometrial differentiation and polarity on the invasivenes so f EVT cells improves our understanding of the relevance of endometrial receptivity for early implantation and may contribute to higher success rates in assisted reproductive technology.