Interaction of bovine epithelial lens (BEL) cells with extracellular matrix (ECM) and eye-derived growth factor (EDGF). II. Partial re-expression of the differentiated collagen distribution and phenotype.

The differentiated phenotype of bovine epithelial lens (BEL) cells consists primarily of type IV collagen production with homogeneous cellular form and monolayer organization. We have previously described how, after several subcultures, BEL cells lost this phenotype, which was replaced by a complex collagen mixture consisting predominantly of type I and type III collagens and a minor proportion of type IV collagen. The cells became irregular and formed multilayers. These dedifferentiated cells can re-express their initial morphological properties when subcultured on an extracellular matrix (ECM) in presence of an eye-derived growth factor (EDGF), as described in the first paper of this series [30]. Furthermore, those cells passaged only one time on ECM + EDGF partially re-express the native differentiated collagen phenotype. The cells synthesize a majority of type IV collagen (up to 65%) with minor amounts of interstitial collagens. As in early subcultured cells, the major proportion of total collagen accumulated in the cell layer. Taken together, the morphological and biochemical data emphasize the relationship between cell shape and collagen phenotype expression. They also provide a reversible system for the study of normal gene expression and pathological alterations.