| Abstract: | The monoclonal antibody ECCD-1 recognizes the Ca2+-dependent cell-cell adhesion molecule of teratocarcinoma stem cells (EC cells) and of a certain class of differentiated epithelial cells. It actively disrupts cell-cell adhesion when added to monolayer cultures of these cells, but does not affect adhesion of mesenchymal or neuronal cells. When ECCD-1 was added to clonal cultures of EC cells (PCC3/A/1 line), all the cells were initially sensitive to the antibody, but after 5 to 6 days of culture a fraction of the cells in certain colonies no longer reacted with the antibody although they expressed alkaline phosphatase activity, which is a marker of undifferentiated EC cells. We isolated these ECCD-1-resistant cells by recloning and examined their differentiation by clonal culture. Most of them differentiated into fibroblastic cells and a few into skeletal muscle-like cells, but none differentiated into any other cell types. From these observations, we suppose that the ECCD-1-resistant population of EC cells are committed to mesenchymal differentiation. The use of ECCD-1, thus, permitted us to detect EC cells at the initial stage of a particular differentiation pathway. |
