Trophoblast cell differentiation: establishment, characterization, and modulation of a rat trophoblast cell line expressing members of the placental prolactin family

Endocrinology. 1991 Dec;129(6):2895-906. doi: 10.1210/endo-129-6-2895.


The purpose of this investigation was to establish and characterize a cell line derived from a rat choriocarcinoma and to evaluate the usefulness of the cell line as an in vitro model for studying trophoblast cell differentiation. A cell line was generated from choriocarcinoma explants and named Rcho-1. The cell line consisted of a mixture of cell types, including small cells growing in clusters and giant cells possessing very large nuclei. This characteristic morphology was maintained through at least 23 passages and in a series of clonal cell lines isolated from the parent Rcho-1 cell line. The Rcho-1 cell line was capable of expressing placental lactogen-I (PL-I), PL-II, PRL-like protein-A (PLP-A), and PLP-C mRNAs when cultivated in vitro; however, the Rcho-1 cells expressed only PL-I when grown beneath the kidney capsule of host rats. The Rcho-1 cell line did not express PLP-B under any experimental condition. This pattern of placental PRL expression was maintained for 23 passages. Rcho-1 cells synthesized and secreted PL-I, PL-II, and PLP-A proteins with biochemical characteristics similar to those of their placental counterparts. PL-I and PL-II mRNAs were specifically localized to giant cells. Morphological appearance and placental PRL expression were used as indices for monitoring the differentiation state of Rcho-1 cells grown under various conditions. Both morphological and functional trophoblast cell differentiation were induced by maintaining the Rcho-1 cells in postconfluent culture conditions. Postconfluent Rcho-1 cultures were characterized by an increased percentage of giant cells and an induction of placental PRL expression. Some clonal cell lines derived from the parent Rcho-1 cell line exhibited distinct patterns of differentiation and placental PRL expression. In summary, we have established a rat trophoblast cell line capable of expressing a differentiated phenotype. The differentiated phenotype includes both morphological and functional parameters and can be modulated in vitro. This cell line is a unique model for studying the control of placental PRL gene expression and the regulation of trophoblast cell differentiation.

Publication types

  • Research Support, U.S. Gov't, Non-P.H.S.
  • Research Support, U.S. Gov't, P.H.S.

MeSH terms

  • Animals
  • Blotting, Northern
  • Cell Differentiation
  • Cell Division
  • Choriocarcinoma
  • Female
  • Gene Expression*
  • Immunosorbent Techniques
  • Male
  • Placenta / metabolism*
  • Placental Lactogen / genetics
  • Pregnancy Proteins / genetics
  • Prolactin / genetics*
  • RNA, Messenger / metabolism
  • Rats
  • Trophoblasts / cytology*
  • Trophoblasts / metabolism
  • Tumor Cells, Cultured


  • Pregnancy Proteins
  • Prl4a1 protein, rat
  • Prl8a3 protein, rat
  • RNA, Messenger
  • placental lactogen II
  • Prolactin
  • Placental Lactogen