Evaluation of Transport Activity Using Mouse Jejunal Epithelial Cell Monolayer Culture System

Caco-2 cells, derived from colorectal cancer cells, are generally used to evaluate drug absorption in the gastrointestinal tract. However, differences between Caco-2 and normal intestinal cells have been observed. Cells cultured directly from crypts are maintained in their biological state. Therefore, we developed a rapid and easy method of monolayer culture of epithelial cells isolated from the jejunum of mice. We analyzed the usefulness of the jejunal epithelial cell monolayer culture system as a research tool and evaluated changes in the transport activity and mRNA expression of transporters. We focused on P-glycoprotein (P-gp) and peptide transporter 1 (Pept1) as representative transporters expressed in the small intestine. A P-gp inhibitor significantly enhanced the accumulation of Rhodamine 123 (Rho123), a substrate of P-gp, indicating that the transport activity of P-gp could be evaluated. Uptake of glycylsarcosine, a Pept1 substrate, significantly decreased in the presence of the Pept1 inhibitor, indicating that the transport activity of Pept1 could be evaluated. Rho123 accumulation significantly decreased in the group treated with calcitriol, an inducer of P-gp and Cyp3a11, suggesting that changes in P-gp expression could be evaluated. Furthermore, we examined whether mRNA expression levels of transporters and drug-metabolizing enzyme were altered. In the calcitriol-supplemented group, P-gp and Cyp3a11 mRNA levels significantly increased. However, no significant differences were observed in Pept1 mRNA levels. Overall, the jejunal epithelial cell monolayer culture system developed from intestinal tissues is a useful research tool for assessing the transport activities and expression variabilities of transporters.