Capacity for hormone production of cultured trophoblast cells obtained from placentae at term and in early pregnancy

Problem: There is an increased doubt about the identity of isolated cytotro phoblast cells at term. Therefore, we compared pregnancy serum levels of th ree hormones [human placental lactogen (hPL), human chorionic gonadotropin (hCG), and leptin] with the capacity for hormone production of early placen tae [EP; 8-13 weeks of gestation (WG)] and term placentae (TP; 38-42 WG). Methods: Serum levels of these hormones were determined in 15 paired matern al (7-41 WC;) and fetal (37-41 WG) samples. Cytotrophoblast cells were isol ated from term (TP; 38-42 weeks) and early (EP; 8-13 weeks)placentae by enz ymatic digestion and subsequent purification on a Percoll gradient These ce lls were cultured for 6 days. The production of the hormones hPL, hCG, and leptin was determined as release during culture + cell content after cultur e - cell content before culture. Results: Serum levels (mean +/- SD; n = 15) at 7-12 and 37-41 WG were 89,65 2 +/- 21,431 and 13,620 +/- 5854 mIU/ml for hCG, 400 +/- 182 and 7088 +/- 2 030 ng/ml for hPL, and 12,675 +/- 4266 and 32,236 +/- 10,961 pg/ml for lept in, respectively. For cultured cells from EP and TP, hCG and hPL showed dif ferent patterns of release during the first 2-3 days. While the release of these two hormones by EP cytotrophoblast cells continued during 6 days in c ulture, their concentrations reached a plateau for TP cytotrophoblasts betw een 4 and 6 days. Leptin was undetectable (< 15 pg/ml) in TP cell cultured media, while for EP all three hormones showed the same release profiles. Pr oduction calculated for 30,000 TP trophoblast cells cultured for 6 days (n = 8) was 2-31 mIU for hCG and 0.5-2 ng for hPL. For EP (n = 11), it was 50- 1070 mIU for hCG, 15-323 ng for hPL, and 137-580 pg for leptin. Net synthes is of hCG and hPL for TP was > 10-fold and <1-fold, respectively. In contra st, the production of all three hormones for EP was at least 100 times the initial cell content. Conclusions: These results demonstrate that trophoblasts from early pregnan cy show much higher production rates of hCG, hPL, and leptin than at term. However, the in vitro findings are difficult to be reconciled with the diff erent serum concentrations of the two hormones hPL and leptin observed duri ng the course of pregnancy.