Characterization, organoid formation and differentiation potential of the novel term trophoblast cell line TB/SVTERT350

Herein, we molecularly characterize the novel human term trophoblast cell line TB/SVTERT350 and show that it meets the criteria for trophoblast identity and subtype specification. TB/SVTERT350, cultured under stemness conditions in 2D or 3D, express trophoblast progenitor markers such as E-cadherin, TEAD4 and YAP1 and develop into CGβ-producing syncytiotrophoblast and HLA-G-expressing extravillous trophoblasts in the respective differentiation media. Expanding TB/SVTERT350 organoids share structural similarities with primary trophoblast organoids and express NOTCH1 suggesting that the cell line exhibits phenotypic traits of proximal cell column trophoblasts. In summary, TB/SVTERT350 could represent a reliable model for studying mechanisms of placental growth and differentiation. • TB/SVTERT350 cells, grown under stemness conditions, express markers of trophoblast identity and expansion. • Supplementation of forskolin or removal of the WNT activator CHIR99021 promotes syncytialization and extravillous trophoblast (EVT) differentiation, respectively, in 2D-cultivated TB/SVTERT350. • TB/SVTERT350 form 3D organoids mimicking the structural organization of primary trophoblast-derived organoids. • Removal of WNT activation upregulates HLA-G in the outer regions of TB/SVTERT350 organoids suggesting correct spatial orientation of EVT differentiation. • Proliferative 2D and 3D cultures of TB/SVTERT350 express NOTCH1, suggesting that the cell line might display characteristics of proximal cell column trophoblasts.