Related Experiment Video
Updated: Sep 28, 2026

Using Caco-2 Cells to Study Lipid Transport by the Intestine
Published on: August 20, 2015
Enhanced permeability of molecular weight markers and poorly bioavailable compounds across Caco-2 cell monolayers
Donna S Cox1, Sangeeta Raje, Huanling Gao
1Pharmacokinetics Biopharmaceutics Laboratory, Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland, 100 Penn Street, AHB, Baltimore, Maryland 21201-6808, USA.
Purpose:
Zonula occludens toxin (Zot), a protein elaborated from Vibrio cholerae, has been shown to be capable of reversibly opening tight junctions. The objective of this work was to determine the stability of Zot and to examine the permeability of a series of molecular weight hydrophilic markers and therapeutic agents in the presence of Zot.
Method:
The transport of molecular weight markers (i.e., PEG 4000, FITC-dextran 10.000 and inulin) and therapeutic agents (i.e., acyclcovir, cyclopsorin, paclitaxel. doxorubicin) was evaluated with Zot (0, 2, and 4 microg/mL) using Caco-2 cell monolayers.
Results:
Zot was found to be stable over a 10-day period. Significantly higher (p < 0.05) permeability of the molecular weight markers, in lin, and PEG4000 were observed with Zot (4 microg/mL). The transport of each therapeutic marker was significantly increased with paclitaxel displaying a >3-fold enhancement in Papp values with Zot (4 microg/mL). A 30% decrease in transepithelial electrical resistance values wa observed, which returned to baseline 30 min after Zot was removed.
Conclusions:
Considering the problems of poor oral bioavailability, it is concluded that Zot is a promising drug delivery technology to be used to enhance drug transport across the intestinal mucosa. Future applications are targeted at assessing its usefulness in oral drug delivery using in vivo systems.
Related Concept Videos
Methods for Studying Drug Absorption: In vitro
The diffusion cell method uses a two-compartment cell, including a donor compartment with the drug solution, which simulates the environment where the drug is applied, and a receptor compartment with a buffer solution, which simulates the environment...
Tight Junctions
Cellular Membranes and Drug Transport
Phospholipids arrange themselves into a bilayer, with hydrophilic heads oriented outward and hydrophobic tails facing inward.
Drug Absorption Mechanism: Passive Membrane Transport
Facilitated Diffusion
In this process, substrates such as organic compounds and ions interact with a transporter on one side, triggering conformational changes in proteins that enable...

