Fig. 1

Characterization of primary early cytotrophoblast cells (early-CTBs) and primary human placenta-derived mesenchymal stem cells (hPDMSCs). a Morphological features of hPDMSCs isolated from human term placental tissue and passaged. The morphological features of primary hPDMSCs isolated from human full-term placental tissue (left), and the morphology features as fibroblast-like adherent cells after trypsin digestion at 0 passage (middle) and at 3rd passage (right). Scale bar 200 μm. b The cell surface phenotype of hPDMSCs was analyzed by flow cytometric analysis. The cells were positive for mesenchymal cell markers such as CD73, CD90, and CD105, and negative for hematopoietic cell markers such as CD34 and CD45. c hPDMSCs exhibited multilineage differentiation potential including endotheliocytes, osteoblasts, and adipocytes when they were cultured in the corresponding differentiation medium. The induced endothelial cells were stained with von Willebrand factor (vWF) (left), osteoblast with alkaline phosphatase (middle), and adipocytes with oil red O (right). Scale bar 100 μm. d Immunofluorescence was conducted to evaluate markers of cytotrophoblast cells in the placenta villus (left), the isolated primary early-CTBs (middle), and HTR8 cells line (right). Cytotrophoblast cells were stained by CK7 (red), mesenchymal cells by vimentin (green), and the cell nuclei were counterstained by 4′, 6-diamidino-2-phenylindole, dihydrochloride (DAPI) (blue). Scale bar 200 μm. e The early-CTBs formed multiple epithelial-like cell clones and the syncytiotrophoblast cells with the extension of the culture time. The proliferative primary CT under a light microscope (left) and the syncytiotrophoblast cells under a light microscope (middle) and immunofluorescence analyze (right). Scale bar 200 μm. g The markers of cytotrophoblasts were analyzed by flow cytometric analysis. The cells were positive for CK7 (cytotrophoblast marker) and negative for vimentin (mesenchymal cell marker)