Morphology related functionality in Caco2/HT-29 co-culture cells : a versatile model of human intestinal epithelium

Caco2 and HT-29 cells represent two frequently used cell models of intestinal epi-thelium. Both cell lines consist of cells of tumour origin induced to differentiate but while Caco2 cells differentiate mainly toward absorptive entherocytes, HT-29 cells differentiate toward entero-endocrine/mucus secreting, goblet entherocytes (Zweibaum et al. 1991). Co-cultures of Caco2 /HT-29 cells, when completely char-acterized, could represent a more physiological model for drug absorption and in-testinal tumor studies. Caco2/HT-29 co-culture at full confluency shows a prolifera-tion rate, measured by tetrazolium colorimetric assay (MTT), intermediate to that of parental HT-29 and Caco2 cells. Protein content progressively increases with days of post confluence, corresponding to the presence of multilayers, as revealed by TEM. Alkaline phosphatase and sucrase-isomaltase are two known biochemical markers of intestinal cell differentiation. In Caco2/HT-29 co-cultures the ALP activi-ty progressively increases while the sucrase-isomaltase activity decreases with days at post-confluence. These results are similar to the ones reported for the parental cell lines and reflect the development of a functionally differentiated epithelium, in agreement with the observed morphology. Trans electrical epithelial resistance (TEER), indicative of the barrier properties of the formed monolayer, increases with days at post confluence up to the 6th day. Taken together the present data identifies Caco2/HT-29 co-cultures here analysed as a valid model of human intestinal epi-thelium, characterized by the presence of more than one intestinal citotype thus with wide possibilities of use for all the studies needing a physiological model as much as possible comparable to human intestine.