Scientific background

WHAT ARE CACO-2 CELLS?

The Caco-2 cell line is a continuous monolayer of heterogeneous human epithelial colorectal adenocarcinoma cells, developed by the Sloan-Kettering Institute for Cancer Research through research conducted by Dr. Jorgen Fogh. 

Although derived from a colon carcinoma, when cultured under specific conditions the cells become differentiated and polarized such that their phenotype, morphologically and functionally, resembles the enterocytes lining the small intestine. Caco-2 cells express tight junctions, microvilli, and a number of enzymes and transporters that are characteristic of such enterocytes: peptidases, esterases, P-glycoprotein, uptake transporters for amino acids, bile acids carboxylic acids, etc. 

WHAT ARE THEY USED FOR?

The human intestinal Caco-2 cell line has been extensively used over the last twenty years as a model of the intestinal barrier.

Caco-2 cells are most commonly used not as individual cells, but as a confluent monolayer on a cell culture insert filter. When cultured in this format, the cells differentiate to form a polarized epithelial cell monolayer that provides a physical and biochemical barrier to the passage of ions and small molecules. The Caco-2 monolayer is widely used across the pharmaceutical industry as an in vitro model of the human small intestinal mucosa to predict the absorption of orally administered drugs. The correlation between the in vitro apparent permeability across Caco-2 monolayers and the in vivo fraction absorbed is well established.

WHY ARE THEY USED?

Caco-2 monolayer properties allow it to be a reliable model for testing drugs in pre-clinical phases.

Before pharmaceutical companies start clinical trials on a drug, they conduct extensive pre-clinical studies. These involve in vitro (test tube or cell culture) and in vivo (animal) experiments using wide-ranging doses of the study drug to obtain preliminary efficacy, toxicity and pharmacokinetic information. CaCo-2 cell lines are a model of in vitro cell culture, and they are used as an alternative or a complement of animal testing. Such tests assist pharmaceutical companies to decide whether a drug candidate has scientific merit for further development as an investigational new drug.

New chemical entities (NCEs, also known as new molecular entities or NMEs) are compounds which emerge from the process of drug discovery. These will have promising activity against a particular biological target thought to be important in disease. However, little will be known about the safety, toxicity, pharmacokinetics and metabolism of this NCE in humans. It is the function of drug development to assess all of these parameters prior to human clinical trials.

 

SEMINAL REFERENCES

 

REGULATORY GUIDELINES

DOT. Code of Federal Regulations, Title 49. 1.

FDA-Guidance. 2012.

Waiver of In Vivo Bioavailability and Bioequivalence Studies for Immediate-Release Solid Oral Dosage Forms Based on a Biopharmaceutics Classification System

Drug Interaction Studies — Study Design, Data Analysis, and Implications for Dosing and Labeling

The BCS, BDDCS, and Regulatory Guidances

EMA-Guidance. 2010. 

EMA-Guidance. 2012. 

IATA, I.A.T.A. 2014. Dangerous Goods Regulations 56th Edition.

 

CACO-2 AS PERMEABILITY MODEL

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CACO-2 CLONES CHARACTERIZATION

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