Absorption, transportation, and first-pass metabolism of xenobiotics, drugs and nutrients taken orally occurs in the intestine, which is a major organ expressing cytochrome P450 enzymes (CYP) and transporters. Caco-2 is a human colon carcinoma cell line widely employed as a model for xenobiotic absorption, transportation, and metabolism in the intestinal tract as it can spontaneously differentiate to become small intestinal enterocytes. Culturing factors influence differentiation of Caco-2 as well as expression of CYPs and drug transporters. Culturing period, medium composition, type of filter membrane inserts, and the seeding density, account for the major factors affecting cell differentiation and the expression of CYP and transporter. Therefore, determining the optimal conditions for Caco-2 culturing is of strong concern depending on the aim and experimental design of the study.
