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Abstract
There are two in vitro models for forming trophoblast-like cells from human embryonic stem ce s (hESCs):(i) in an adherent culture treated with bone morphogenic protein(BMP) 4, and( ) cultured as embryoid bodies (EBs) and allowed to spontaneously differentiate. The hypothesis being tested is that in these two culture systems trophoblast-like cells are formed and they biosynthesize and secrete placental hormones. The goal of this project was to test this hypothesis by hormone analysis, gene expression analysis, and immunohistochemistry of the differentiatedh ESCs. Both culture conditions resulted inproduction of hCG, 17?-estradiol, and progesterone and up-regulation of trophoblast-related genes (CGB, KRT7, MMP9, GATA2, and GATA3). Side-chain cleavage enzyme (CYP11A1) and aromatase (CYP19A1), two enzymes necessary for steroid biosynthesis, were up-regulated in both culture conditions. In the study withBMP4, trophoblast formation was to the exclusion ofa other cell types as germline markers and pluripotency markers were down regulated. The EBs stained positive for CYP11A1 and3-beta-hydroxysteroiddehydrogenase in immunohistochemistry. Thus, trophoblast-like differentiation can be achieved with HESCs by addition of BMP4 or by specified culture conditions leading to EB formation, and these cells are capable of steroidogenesis.