Human Chorionic Gonadotropin Expression in Human Trophoblasts from Early Placenta: Comparative Study Between Villous and Extravillous Trophoblastic Cells

Abstract

Human trophoblast differentiates into two pathways: extravillous cytotrophoblasts (EVCT) that invade the uterus wall and villous cytotrophoblasts (VCT) that fuse to form the syncytiotrophoblast (ST) involved in placental exchanges and endocrine function. It is established that hCG is produced and secreted by the ST into the maternal compartment where it plays a key endocrine role and stimulates ST formation in an autocrine manner. Herein, we investigated hCG expression in early placentas by immunohistochemistry using different antibodies. We then compared hCG secretion by primary cultures of VCT and EVCT isolated from the same first trimester human chorionic villi. In situ hCG was immunodetected in EVCT all along their invasive differentiating pathway excepted in cells near the stromal core of the proximal column. hCG expression was confirmed in vitro by immunocytochemistry and hCG secretion quantified in cell supernatants. Interestingly, whereas hCG secretion increased during VCT differentiation into ST (from 60 to 350 UI/L/µg DNA), EVCT secretion remained constant and at a high level during the same culture period (160 UI/L/µg DNA). Our data demonstrated that in addition to the ST, invasive EVCT also expressed and secreted high levels of hCG, suggesting a specific paracrine and/or autocrine role for hCG from EVCT origin.3

Effect of vitrification versus slow freezing of human day 3 embryos on β-hCG levels

“…The amount of hCG actually reflect the number of viable cytotrophoblast and syncytiotrophoblast cells producing the hormone [1,2]. Our results indicate that, at equivalent time intervals subsequent to fertilization, serum hCG concentrations are significantly higher in ongoing pregnancies achieved after slow-freezing embryo transfer compared with those after vitrified embryo transfer.…”

“…A number of studies have reported that β-hCG level represents trophoblastic mass and function and is predictive of pregnancy outcomes [1,[3][4][5][6][7], yet early β-hCG values after frozen embryo transfers have not studied. We further evaluated whether vitrification of day 3 embryos have an effect on β-hCG level of early pregnancy.…”

“…The embryos were washed and cultured in cleavage medium (G-1, Vitrolife Sweden AB, Sweden) with 12 % SSS and incubated at 6 % CO 2 , 37 o C incubators for 48 h before being frozen. Embryonic development was assessed on Day 3 after oocyte retrieval with an inverted microscope using routine examination of: [1] the number of blastomeres; [2] the degree of cytoplasmic fragments; [3] the uniformity of blastomeres. Embryos morphology was scored as: grade 1, equal blastomeres with no obvious fragmentation; grade 2, <20 % fragmentation and/or unequal blastomeres; grade 3: 20-50 % cytoplasm fragmentation; grade 4: >50 % cytoplasm fragmentation.…”

“…Human chorionic gonadotropin (hCG) is a glycoprotein hormone, secreted by both the cytotrophoblast and syncytiotrophoblast [1]. It is present in the maternal serum as early as 6~7 days after fertilization [1].…”

“…It is present in the maternal serum as early as 6~7 days after fertilization [1]. Since hCG is the first observable signal of trophoblast proliferation in maternal blood, it is used for the early detection of pregnancy [2].…”