ENDOTHELIN-1 BINDING-SITES AND IMMUNOREACTIVITY IN THE CULTURED HUMANPLACENTAL TROPHOBLAST - EVIDENCE FOR AN AUTOCRINE AND PARACRINE ROLE FOR ENDOTHELIN-1

In human placenta, endothelin (ET) could derive from maternal, fetal, and/or endogenous sources. Therefore, localization of ET-1 was investi gated by immunohistochemistry in human term placenta and in cultured t rophoblasts. In sections of placenta, ET-I immunoreactivity (ET-1 IR) was specifically detected in the endothelium of the vessels and in the syncytiotrophoblasts of the villi. ET-1 IR was also detected in the d ecidual cells and in the extravillous crytotrophoblasts of the basal p late. The extravillous cytotrophoblasts of the chorionic plate and of the placental septa also exhibited strong ET-1 IR. For trophoblast cul ture, cytotrophoblastic cells were obtained from placental villi by tr ypsin-DNAse dispersion, further purified on a Percoll gradient, and en riched by employing a monoclonal anti-HLA class I antibody. After diff erent periods of culture of purified cytotrophoblastic cells (1-5 days ), ET-I IR was observed in 95% of cells: cytotrophoblastic cells, trop hoblast aggregates, and syncytiotrophoblasts. The presence of ET-1,2 i mmunoreactivity (ET-1,2 IR) in the culture media was demonstrated by r adioimmunoassay. A uniform daily production of the peptide was observe d over at least 5 days (approximately 50 fmol/10(6) cells/24 h). Furth ermore, trophoblastic cells that had been cultured for 5 days containe d significant amounts of ET-1,2 IR (24 fmol/10(6) cells). These result s suggest a trophoblastic origin for ET-1 and support the hypothesis o f a paracrine and autocrine action of the peptide in the physiology of the trophoblast and placenta.