Correlation of in vitro cytotoxicity with paracellular permeability in mortal rat intestinal cells.

INTRODUCTION

The rat small intestinal cell line, IEC-18, was used as an in vitro model to differentiate between acute cytotoxicity (AC) and paracellular permeability (PP) of selected chemicals.

METHODS

This study compares the low resistance rat intestinal mortal cell line, IEC-18 (transepithelial electrical resistance, TEER=160+/-10 Omega cm(2)) with the high resistance human intestinal cell line, Caco-2 (TEER=900+/-100 Omega cm(2)). The two cell lines differ in state of differentiation, TEER and paracellular permeability characteristics. The IEC-18 cell line is originated from the ileum and resembles more closely the small intestine than the Caco-2. Cytotoxicity was carried out using MTT cell viability assay in 96-well plates for 24-h exposure time. PP was measured using TEER (membrane integrity indicator) and PP markers such as [(3)H]-D-mannitol, lucifer yellow (LY) and FITC-dextran (fluorescein-dextran) on cells grown on inserts.

RESULTS

The data showed that there is a high correlation (R(2)=0.99) between MTT and TEER using IEC-18 cell for 24-h exposure time. IEC-18 is as sensitive as Caco-2 for both MTT and TEER measurements. Decrease in TEER is inversely proportional with increase in PP of tight junction indicators. There is a good correlation between IC(50)'s MTT, TEER and Registry of Cytotoxicity (RC) data.

DISCUSSION

Based on the results from the experiments, IEC-18 can be used as an in vitro model to differentiate between concentrations needed for AC and those required for PP.