Reconstruction of pleomorphic adenoma of the salivary glands in three-dimensional collagen gel matrix culture.

The morphogenesis of salivary gland pleomorphic adenoma was examined in vitro using three-dimensional (3-D) collagen gel culture. Pleomorphic adenoma cells were isolated from three parotid gland tumours and cultured as monolayers, after which they were subcultured in floating-collagen gel sandwiches. Cells cultured in both conditions were immunohistochemically characterized and compared using antibodies against various proteins representative of each histological component of salivary glands. Monolayers had myoepithelial characteristics, being positive for vimentin and α-smooth muscle actin. In collagen gels, however, the cells assembled in epithelial nests, showing an architecture similar to that of pleomorphic adenoma. The nests were composed of duct-lining epithelial cells that were positive for epithelial markers, surrounded by myoepithelial cells. Collagen gel culture induces multi-directional differentiation of adenoma cells, suggesting that pleomorphic adenomas originate from stem or reserve cells.