Permeability across a monolayer of polarized epithelial cells is a fundamental property of a compound that can be measured through our ExpressPlus™ assays.
We do more assays with Caco-2 cell monolayers than anyone in the world.
No one is more knowledgeable than Absorption Systems when it comes to Caco-2 cells. A combination of experience and rigorous cell biology QC processes makes it possible for us to interpret your compound’s test results.
Express Unidirectional Permeability Through Caco-2 Monolayers
Express Bidirectional Permeability Through Caco-2 Monolayers
Express MDR1-MDCK for BBB Penetration Potential
Express P-gp Substrate Assessment Using MDR1-MDCK Cell Monolayers
Express P-gp Inhibitor Assessment Across Cell Monolayer
Express BCRP Inhibitor Assessment
Express PepT1 Substrate Assessment in Caco-2 Cell Monolayers
Express P-gp Substrate Assessment in CellPort CPT-B1 BCRP Knockdown Cells
Express BCRP Substrate Assessment in CPT-B1 BCRP Knockdown Cells
Express BCRP Substrate in CPT-B1
Express P-gp Substrate in CPT-P1
Different cell lines are used as in vitro models for different purposes.
Caco-2 cell monolayers predict not only intestinal absorption but also drug-drug interactions involving transporters. Likewise, MDR1-MDCK cell monolayers are used to predict drug-drug interactions involving the efflux transporter P-glycoprotein as well as blood-brain barrier (BBB) penetration.
Other ExpressPlus assays utilizing the same test format identify substrates and inhibitors of transporters. Taken together, these studies help identify compounds with drug-like properties. The fixed protocols and rapid turnaround time make them ideal for screening large numbers of compounds early in drug discovery. At a later stage, when the same tests are run as custom assays, including test conditions optimized for a given compound, additional bioanalytical rigor, etc., you can count on getting the same results. That’s because the Absorption Systems philosophy is, wherever possible, to use the same rigorously validated test systems throughout the drug development continuum.
Background on Permeability Testing Tools and Methods
Redefining the Threshold for Permeability Classification
Caco-2 Application Pioneered by Ismael Hidalgo
In Situ Organ Perfusion
Simplified with Exemplary Service
Bidirectional Monolayer Format
For permeability assays we use the bidirectional monolayer transport format, a confluent monolayer of polarized epithelial cells established on a semi-permeable filter separating the two chambers of a Transwell® apparatus. Caco-2 cells form a polarized monolayer in about 21 days; MDR1-MDCK cells take about 7 days. The rate of transport of a test compound across the monolayer is measured in both directions, by adding the compound to the apical chamber and sampling from the basolateral chamber (apical-to-basolateral or A-to-B permeability) or by doing the opposite (for B-to-A permeability).
EA201 Express Unidirectional Permeability Through Caco-2 Monolayers
EA202 Express Bidirectional Permeability Through Caco-2 Monolayers
EA203 Express MDR1-MDCK for BBB Penetration Potential
EA204 Express P-gp Substrate Assessment Determined Using MDR1-MDCK Cell Monolayers
EA222 Express P-gp Inhibitor Assessment Across Cell Monolayers
EA223 Express BCRP Inhibitor Assessment
EA224 Express PepT1 Substrate Assessment in Caco-2 Cell Monolayers
EA250 Express P-gp Substrate Assessment in CellPort CPT-B1 BCRP Knockdown Cells
EA251 Express BCRP Substrate Assessment in CPT-B1 BCRP Knockdown Cells
EA251 Express BCRP Substrate in CPT-B1
EA252 Express P-gp Substrate in CPT-P1
EA701 Express Plasma Protein Binding (human plasma) Assay Data Sheet
EA702 Express Plasma Protein Binding (rat plasma) Assay Data Sheet
EA703 PPB – Ultracentrifugation
EA704 PPB – Equilibrium Dialysis
EA705 PPB – Ultrafiltration
EA706 Red Blood Partitioning
EA707 Express Fraction Unbound (rat or mouse brain)
EA708 Express Plasma Protein Binding (mouse plasma) Assay Data Sheet
EA709 Express Plasma Protein Binding (primate plasma) Assay Data Sheet
EA710 Express Plasma Protein Binding (dog plasma) Assay Data Sheet
EA713 Express Blood to Plasma Partitioning in Mice Rats and Humans
EA813 Express ABT Exposure in Rats
EA982 Express Formulation Assessment
Fabre G, et al., Correlation between oral drug absorption in humans, and apparent drug permeability in TC-7 cells, a human epithelial intestinal cell line: comparison with the parental Caco-2 cell line. Pharm Res. 1998 May; 15(5):726-33.
Hunter J, et al., Functional expression of P-glycoprotein in apical membranes of human intestinal Caco-2 cells. Kinetics of vinblastine secretion and interaction with modulators. J Biol Chem. 1993 Jul 15; 268(20):14991-7.
Rautio, J, et al., In Vitro P-glycoprotein inhibition assays for assessment of clinical drug interaction potential of new drug candidates: A recommendation for probe substrates. Drug Metab Disp. 2006; 34 (5): 786-92.
Sambuy Y, et al., The Caco-2 cell line as a model of the intestinal barrier: influence of cell and culture-related factors on Caco-2 cell functional characteristics. Cell Biol Toxicol. 2005 Jan; 21(1):1-26.
Taub ME, et al., Functional assessment of multiple Pglycoprotein (P-gp) probe substrates: influence of cell line and modulator concentration on P-gp activity. Drug Metab Dispos. 2005 Nov; 33(11):1679-87. Epub 2005 Aug 10.
When would I use one of your excised tissue permeability models?
To ask mechanistic questions, e.g.:
Is my prodrug converted to the active moiety during absorption?
Is the poor oral bioavailability of my drug due to enzymatic degradation during absorption?
Is the absorption of my drug limited to a specific region of the gut?
Why do you use both Caco-2 and MDR1-MDCK cell monolayers?
We use them in a complementary fashion, particularly for P-gp interactions.
For P-gp interactions, MDR1-MDCK cells offer the advantage of over-expressing only the transporter of interest; however, we have seen both false positives and false negatives with this model.
Caco-2 cells express multiple efflux transporters, which can make it difficult to identify which transporter is involved.
Caco-2 cell monolayers predict intestinal absorption, whereas MDR1-MDCK cell monolayers are better for prediction of BBB penetration.
We are the drug absorption experts
No one does more Caco-2 cell assays than Absorption Systems.
Multiple uses for the same test system
Multiple test systems for different purposes
The same well-validated in vitro test systems from screening through NDA
What are the advantages and uses of the Caco-2 monolayer model?
Caco-2 is a human cell line.
The correlation between in vitro Caco-2 permeability and in vivo human absorption of orally administered drugs is well-established.
CYP-mediated drug metabolism is essentially nil, which simplifies the bioanalysis and interpretation of many permeability experiments.
We have validated the Caco-2 model for both permeability and transporter interactions, which can help you avoid having to do certain clinical drug-drug interaction studies.