Caco-2
Encyclopedia
The Caco-2 cell line is a continuous line 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 (large intestine
) 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. They are commercially available through the American Type Culture Collection
(ATCC; Manassas, VA, USA).
When looking at Caco-2 cell cultures microscopically, it is evident even by visual inspection that the cells are heterogeneous. As a result, over the years the characteristics of the cells used in different laboratories around the world have diverged significantly, which makes it difficult to compare results across labs.
Caco-2 cells are most commonly used not as individual cells, but as a confluent monolayer
on a cell culture insert filter (e.g., Transwell). 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 (P¬app) across Caco-2 monolayers and the in vivo fraction absorbed (fa) is well established.Transwell diagram
This application of Caco-2 cells was pioneered in the late 1980s by Ismael Hidalgo, working in the laboratory of Ron Borchardt at the University of Kansas, and Tom Raub, who was at the Upjohn Company at the time. Following stints at SmithKline Beecham and Rhone-Poulenc Rorer, Hidalgo went on to co-found a company, Absorption Systems, in 1996, where he remains as Chief Scientist.
The considerable impact of the Caco-2 cell monolayer model can be measured in at least two ways. First, considering that poor pharmacokinetic properties accounted for ~40% of drug failures in development in the early 1990s and only ~10% by 2009, an interval in which Caco-2 monolayers were widely used throughout the pharmaceutical industry to predict absorption, it is not unreasonable to attribute some of that shift to this simple yet powerful model. Second, the 1989 Gastroenterology paper that demonstrated the utility of the model for this application has been cited more than 1000 times since its publication.
The versatility of Caco-2 cells is demonstrated by the fact that, even to this day, they are serving as the basis for the creation of innovative new models that are contributing to our understanding of drug efflux transporters such as P-glycoprotein (ABCB1) and BCRP (ABCG2). RNA interference has been used to silence the expression of individual efflux transporters, either transiently or long-term.
Epithelium
Epithelium is one of the four basic types of animal tissue, along with connective tissue, muscle tissue and nervous tissue. Epithelial tissues line the cavities and surfaces of structures throughout the body, and also form many glands. Functions of epithelial cells include secretion, selective...
colorectal
Colon (anatomy)
The colon is the last part of the digestive system in most vertebrates; it extracts water and salt from solid wastes before they are eliminated from the body, and is the site in which flora-aided fermentation of unabsorbed material occurs. Unlike the small intestine, the colon does not play a...
adenocarcinoma
Adenocarcinoma
Adenocarcinoma is a cancer of an epithelium that originates in glandular tissue. Epithelial tissue includes, but is not limited to, the surface layer of skin, glands and a variety of other tissue that lines the cavities and organs of the body. Epithelium can be derived embryologically from...
cells, developed by the Sloan-Kettering Institute for Cancer Research
Memorial Sloan-Kettering Cancer Center
Memorial Sloan–Kettering Cancer Center is a cancer treatment and research institution founded in 1884 as the New York Cancer Hospital...
through research conducted by Dr. Jorgen Fogh.
Although derived from a colon (large intestine
Large intestine
The large intestine is the third-to-last part of the digestive system — — in vertebrate animals. Its function is to absorb water from the remaining indigestible food matter, and then to pass useless waste material from the body...
) carcinoma
Carcinoma
Carcinoma is the medical term for the most common type of cancer occurring in humans. Put simply, a carcinoma is a cancer that begins in a tissue that lines the inner or outer surfaces of the body, and that generally arises from cells originating in the endodermal or ectodermal germ layer during...
, when cultured under specific conditions the cells become differentiated and polarized such that their phenotype
Phenotype
A phenotype is an organism's observable characteristics or traits: such as its morphology, development, biochemical or physiological properties, behavior, and products of behavior...
, morphologically and functionally, resembles the enterocytes lining the small intestine
Small intestine
The small intestine is the part of the gastrointestinal tract following the stomach and followed by the large intestine, and is where much of the digestion and absorption of food takes place. In invertebrates such as worms, the terms "gastrointestinal tract" and "large intestine" are often used to...
. Caco-2 cells express tight junctions, microvilli, and a number of enzymes and transporters that are characteristic of such enterocytes: peptidases, esterases, P-glycoprotein
P-glycoprotein
P-glycoprotein 1 also known as multidrug resistance protein 1 or ATP-binding cassette sub-family B member 1 or cluster of differentiation 243 is a glycoprotein that in humans is encoded by the ABCB1 gene...
, uptake transporters for amino acids, bile acids carboxylic acids, etc. They are commercially available through the American Type Culture Collection
American Type Culture Collection
The American Type Culture Collection is a private, not-for-profit biological resource center whose mission focuses on the acquisition, authentication, production, preservation, development and distribution of standard reference microorganisms, cell lines and other materials for research in the...
(ATCC; Manassas, VA, USA).
When looking at Caco-2 cell cultures microscopically, it is evident even by visual inspection that the cells are heterogeneous. As a result, over the years the characteristics of the cells used in different laboratories around the world have diverged significantly, which makes it difficult to compare results across labs.
Caco-2 cells are most commonly used not as individual cells, but as a confluent monolayer
Monolayer
- Chemistry :A Langmuir monolayer or insoluble monolayer is a one-molecule thick layer of an insoluble organic material spread onto an aqueous subphase. Traditional compounds used to prepare Langmuir monolayers are amphiphilic materials that possess a hydrophilic headgroup and a hydrophobic tail...
on a cell culture insert filter (e.g., Transwell). 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 (P¬app) across Caco-2 monolayers and the in vivo fraction absorbed (fa) is well established.Transwell diagram
This application of Caco-2 cells was pioneered in the late 1980s by Ismael Hidalgo, working in the laboratory of Ron Borchardt at the University of Kansas, and Tom Raub, who was at the Upjohn Company at the time. Following stints at SmithKline Beecham and Rhone-Poulenc Rorer, Hidalgo went on to co-found a company, Absorption Systems, in 1996, where he remains as Chief Scientist.
The considerable impact of the Caco-2 cell monolayer model can be measured in at least two ways. First, considering that poor pharmacokinetic properties accounted for ~40% of drug failures in development in the early 1990s and only ~10% by 2009, an interval in which Caco-2 monolayers were widely used throughout the pharmaceutical industry to predict absorption, it is not unreasonable to attribute some of that shift to this simple yet powerful model. Second, the 1989 Gastroenterology paper that demonstrated the utility of the model for this application has been cited more than 1000 times since its publication.
The versatility of Caco-2 cells is demonstrated by the fact that, even to this day, they are serving as the basis for the creation of innovative new models that are contributing to our understanding of drug efflux transporters such as P-glycoprotein (ABCB1) and BCRP (ABCG2). RNA interference has been used to silence the expression of individual efflux transporters, either transiently or long-term.
See also
- Cell cultureCell cultureCell culture is the complex process by which cells are grown under controlled conditions. In practice, the term "cell culture" has come to refer to the culturing of cells derived from singlecellular eukaryotes, especially animal cells. However, there are also cultures of plants, fungi and microbes,...
- Drug developmentDrug developmentDrug development is a blanket term used to define the process of bringing a new drug to the market once a lead compound has been identified through the process of drug discovery...
- Pre-clinical developmentPre-clinical developmentIn drug development, pre-clinical development is a stage of research that begins before clinical trials can begin, and during which important feasibility, iterative testing and drug safety data is collected....
- PAMPAPAMPAPAMPA is a method which determines the permeability of substances from a donor compartment, through a lipid-infused artificial membrane into an acceptor compartment...
- a non cell-based permeability assay