Derivation of human trophoblast stem cells from placentas at birth
Human trophoblast stem cells (hTSCs) have emerged as a powerful tool for modeling the placental cytotrophoblast (CTB) in vitro. hTSCs were originally derived from CTBs of the first trimester placenta or blastocyst-stage embryos in trophoblast stem cell medium (TSCM) that contains epidermal growth factor (EGF), the glycogen synthase kinase-beta (GSK3{beta}) inhibitor CHIR99021, the transforming growth factor-beta (TGF{beta}) inhibitors A83-01 and SB431542, valproic acid (VPA), and the Rho-associated protein kinase (ROCK) inhibitor Y-27632. Here we show that hTSCs can be derived from CTBs isolated from the term placenta, using TSCM supplemented with a low concentration of mitochondrial pyruvate uptake inhibitor UK5099 and lipid-rich albumin (TUA medium). Notably, hTSCs could not be derived from term CTBs using TSCM alone, or in the absence of either UK5099 or lipid-rich albumin. Strikingly, hTSCs cultured in TUA medium for a few passages could be transitioned into TSCM and cultured thereafter in TSCM. hTSCs from term CTBs cultured in TUA medium as well as those transitioned into and cultured in TSCM thereafter could be differentiated to the extravillous trophoblast and syncytiotrophoblast lineages and exhibited high transcriptome similarity with hTSCs derived from first trimester CTBs. We anticipate that these results will enable facile derivation of hTSCs from normal and pathological placentas at birth with diverse genetic backgrounds and facilitate in vitro mechanistic studies in trophoblast biology. Significance statementHuman trophoblast stem cells (hTSCs) derived from early pregnancy have emerged as a powerful tool for modeling early human placental development in vitro. However, restrictions on derivation of cell lines from fetal tissues limit the availability and genetic diversity of hTSC lines. Also, the associated pregnancy outcome of hTSCs derived from early gestation is unknown. Here we describe the derivation and characterization of hTSCs from placentas obtained at birth. Our results will enable derivation of genetically diverse hTSCs associated with normal and pathological pregnancies, enabling research in placental biology.