Impaired expansion of trophoblast spheroids cocultured with endometrial cells overexpressing cellular retinoic acid-binding protein 2.

We previously showed that the cellular retinoic acid-binding protein 2 (CRABP2) gene was up-regulated during the implantation window period in the endometrium of patients with unexplained recurrent spontaneous abortion. Here, we report that trophoblast spheroids cocultured with a human endometrial cell line stably overexpressing CRABP2 are defective in expansion and exhibit apoptosis, suggesting that the altered expression level of endometrial CRABP2 is involved in abnormal endometrium-trophoblast interaction, which leads to implantation failure.