The secretion and effect of inhibin A, activin A and follistatin on first-trimester trophoblasts in vitro

Objective: The objectives of this study were to investigate the effect of activin A and follistatin on first-trimester cytotrophoblast invasion in culture and to study the secretion of inhibin A, activin A and follistatin by these cellsin vitro.Design and methods: Cytotrophoblasts were isolated from human placental chorionic villous tissue obtained from 6–8, 8–10 and 10–12 weeks gestation. Cells were cultured for 3 days on cell-culture inserts coated with gelatine for invasion studies and in 24-well culture plates for secretion studies. The effects of activin A (10 ng/ml), follistatin (100 ng/ml), interleukin 1β (IL-1β; 10 ng/ml) and epidermal growth factor (EGF; 10 ng/ml) on cytotrophoblast invasion were investigated using a non-radioactive invasion assay. Secretion of inhibin A, activin A and follistatin in the presence of EGF, IL-1β, activin A and follistatin were measured using in-house ELISAs.Results and conclusion: Activin A, follistatin and EGF had a significant stimulatory effect on cytotrophoblast invasion from 6–10 weeks gestation. IL-1β had a significant stimulatory effect at 8–10 weeks and a significant inhibitory effect on invasion at 10–12 weeks gestation. Follistatin also had a significant inhibitory effect on invasion at 10–12 weeks gestation. In the secretion study, activin A secretion at 8–10 weeks was significantly stimulated by IL-1β and EGF. At 10–12 weeks, follistatin and EGF had a significant inhibitory effect on activin A secretion. Follistatin secretion was significantly increased in the presence of IL-1β at 6–8 weeks gestation. Inhibin A secretion was not significantly altered by EGF, IL-1β, activin A and follistatin. These results show that activin A promotes invasion of first-trimester cytotrophoblasts until 10 weeks gestation. There is a difference in the control of secretion of these proteins dependent on the gestation, suggesting that there is a tight regulation in the function of first-trimester trophoblasts depending on the gestational age.