Species: rat (rattus norwegicus)
Tissue: choriocarcinoma
The Rcho-1 cells were derived from a transplantable rat choriocarcinoma (Rcho) originally established by Teshima et al. (1983). The Laboratory of M. Soares received the Rcho transplantable tumor from Michel Vandeputte of Leuven University in Belgium. Vandeputte's group has a long history of studying yolk and trophoblast tumors, mainly from a cancer biologist perspective. The Laboratory of M. Soares collaborated with Vandeputte to examine the expression of placental PRLs by the Rcho transplantable tumor (Faria et al., 1990). Vandeputte's group has published two papers with the cells: 1) a morphological description of the tumors (Verstuyf et al. 1989) and 2) the establishment of a continouos line from the tumors (Verstuyf et al. 1990). An important observation from these studies is that the cells are aneuploid. The Laboratory of M. Soares did not receive the line from Vandeputte but has established their own continuous line (Rcho-1) from the Rcho transplantable tumor (Faria and Soares, 1991). Monoclonal antibodies directed to Rcho cells specifically recignize proliferative cells located in the ectoplacental cone but not trophectoderm of the blastocyst (Verstuyf et al., 1992). Several reports have appeared investigating the effect of Rcho-1 cell transplantation on the production of pituitary prolactin (Tomogane et al., 1991, 1993; Arbogast et al., 1992, 1993; Mathiasen et al., 1992). A few laboratories have utilized the Rcho-1 or the Vandeputte-derived Rcho cell line for studies on the control of trophoblast cell-specific gene expression (Shida et al., 1993; Vuille et al., 1993; Ng et al., 1994; Yamamoto et al., 1994, 1995, 1996; Cross et al. 1995; Dai et al., 1996). Maintenance: The stem cell population can be enriched by growing the cells at low densities and passaging every 2 - 3 days following brief trypsinization. Maintaining cells at higher densities leads to spontaneous differentiation (giant cell formation). The differentiated cells are more adherent than the stem cells and require more vigorous dissociation methods such as scraping. Variations in culture densities, passaging methods, and splitting ratios significantly influence the phenotype of the cell line.Cellular proliferation is dependent upon the presence of some unidentified factors present in fetal bovine serum. The cells grow much better under the conditions of high humidity. Differentiation is induced by growing the cells to confluence in NCTC + 20% FBS and then replacing the serum supplementation with 10% HS. High cell density and the absence of growth stimulation (removal of FBS) facilitate trophoblast giant cell formation. The nutritive needs of differentiating Rcho-1 cells seem to be less than the needs of proliferating Rcho-1 cells; however, differentiating cells minimally require some factors present in horse serum and cannot tolerate the absence of serum for more than 48 hours. Differentiation is a continuum and will proceed over at a least two or three week period in culture. Differentiation will also occur in the presence of FBS; however, under these conditions the cultures are compromised of a greater proportion of stem cells, and thus the cultures are more heterogeneous. In the presence presence of HS, the stem cell population is greatly arrested. The horse serum arrested stem cell population can be revived by reintroduction of FBS. Development of serum free culture conditions facilitating either proliferation or differentiation of the Rcho-1 cells are valuable for studies on the control of trophoblast cell differentiation. Transfection of the Rcho-1 cells: Linzer et al. have successfully utilized Lipofectin or Lipofectamine (GIBCO/BRL) in their experiments of the mouse placental lactogen-I gene promoter (Shida et al., 1993; Ng et al., 1994; Cross et al., 1995). The laboratory of M. Soares has used these reagents in experiments studying the p450scc and P450c17 promoters in Rcho-1 trophoblast cells (Yamamoto et al., 1994, 1995, 1996)
The use of trypsin- EDTA without scraping results in the gradual selection of a different population of cells. Giant cells are not satisfactory removed with the enzyme-chelator treatment. This procedure can be used to select for an enriched population of PL-1 producing cells. The use of scraping without the enzyme-chelator treatment is also in ineffective method for passaging. Scraping the dishes results in the generation of large clumps that do not readily grow when seeded into new flasks.
Passaging the Rcho-1 cells in vivo: Thus far, the laboratory of M.Soares has only transplanted the Rcho-1 cells beneath the kidney capsule. The cells (1-5 million) grown in vitro are harvested as described above and transferred beneath the kidney capsule of 4 week old rats (e.g. Lewis and Holtzman strains) in a volume of 25-50 µl using a 27 gauge needle and 1 ml syringe. The cells grow rapidly and need to be harvested within two weeks, preferably 10-12 days. If the transplants are not harvested then they become necrotic and are useless. A good check for a successful transplant is the presence of stimulated mammary glands. Arbogast et al. (1992) successfully transplanted Rcho-1 cells to the cerebral ventricles.
Culture Medium: NCTC-135 + 20% (heat inactivated) fetal bovine serum to keep cells in proliferative state, NCTC-135 + 10% (heat inactivated) horse serum to push cells to differentiate.
ATCC: -