Morphologic characteristics of the interaction between normal cytotrophoblasts and their malignant counterpart in the development of trophoblastic neoplasia.

OBJECTIVES: To define the biology of the tumor-host cell interaction with regard to cellular kinetics and morphologic changes during cell-cell interaction in an in vitro model of trophoblastic neoplasia. METHODS: Using a coculture in vitro system of cytotrophoblasts and choriocarcinoma cells, we investigated the cellular kinetics and the morphologic changes in these interacting cells. A fully automatic time-lapse image system was used to record phase contrast images of the cocultured cells in a tissue culture chamber. To examine cytoskeletal structure, immunofluorescent-labeled antibodies against intermediate filaments were used. Slides were examined with a confocal laser scanning microscope and subjected to computed analysis. RESULTS: The choriocarcinoma cells attract normal cytotrophoblasts using what resembles pseudopodia to engulf the latter cells and thus form slow-growing colonies. In this process, new hybrid cells are formed, which can be differentiated from their original contributors by morphologic characteristics. CONCLUSION: This phenomenon supports our previous biochemical and molecular data on the role of cell-cell interaction in the complex process of cytotrophoblast transformation and the development of gestational trophoblastic neoplasia.

Activation of human neutrophils after contact with cellulose-based haemodialysis membranes: intracellular calcium signalling in single cells.

PURPOSE OF STUDY: In vitro contact of human leukocytes with cellulose-based dialysis membranes under complement-independent conditions results in activation of various leukocyte functions. To analyse signals involved in the mechanism of cell activation, we measured changes in cytosolic free calcium ([Ca2+]i) in individual human blood neutrophils (PMN) upon contact with flat sheet haemodialysis membranes. RESULTS: By confocal laser-scanning microscopy (CLSM), changes in [Ca2+]i were monitored in Fluo-3-labelled cells up to 10 min after contact with a regenerated cellulose (RC) membrane. Multiple [Ca2+]i transients were observed for cells in contact with RC; biostochastic analysis showed that up to 67% of the PMN responded with a high increase in [Ca2+]i, the rest were low- or non-responding cells. After contact with the new synthetic polycarbonate-polyether (PC-PE) membrane only non-responding cells were seen, indicating reduced cellular contact activation. The increase in [Ca2+]i of cells on RC could be inhibited by 5mM L-fucose. This monosaccharide was recently found to be present in cellulose-based polymers in picomolar concentrations. CONCLUSIONS: The data supports the hypothesis that dialysis-membrane-associated L-fucose residues participate in complement-independent leukocyte activation during haemodialysis therapy.