Transient mosaic patterns of morphological and functional differentiation in the Caco-2 cell line.

To gain further insight on the mosaic expression of specific functional intestinal markers (such as sucrase-isomaltase) in postconfluent Caco-2 cells, a human colon cancer cell line unique in its property to differentiate in vitro into a mature enterocyte-like cell type, a comparative study was undertaken to examine the morphological and functional differentiation of Caco-2 cells at various culture stages. The observations clearly indicate that Caco-2 cells can exist only in three different states in culture: homogeneously undifferentiated (at subconfluence), heterogeneously polarized and differentiated (between 0 and 20 days after confluence), and homogeneously polarized and differentiated (after 30 days). Indeed, in the intermediate state, a strong discrepancy is found among adjacent differentiating cells throughout the monolayer relative to sucrase-isomaltase expression as well as to cell morphology and brush border organization. Back-scattered electron imaging analysis showed a lack of correlation between these parameters at the cellular level. These observations indicate that morphological and functional differentiations of Caco-2 cells progress concomitantly according to a transient mosaic pattern, thus providing evidence that these two processes are not coupled.