Leukemia inhibitory factor (LIF) enhances trophoblast differentiation mediated by human chorionic gonadotropin (hCG)

We investigated the effect of LIF on the differentiation of trophoblasts. Isolated cytotrophoblasts were cultured with and without LIF and cell smears were immunocytochemically analyzed, using anti-hCG antibody. The percentage of differentiated trophoblasts stimulated by 10ng/ml of LIF was about 2.5-fold that in the control culture. The effect of LIF in inducing the differentiation of cytotrophoblasts to syncytiotrophoblasts was dose-dependent. The same effect was shown when hCG was added to the medium. This enhancing effect of LIF on trophoblast differentiation was blocked by adding anti-hCG antibody to the culture system. These results indicate that LIF enhanced trophoblast differentiation by stimulating hCG production in trophoblasts, and not by exerting a direct effect on the trophoblasts.