Caco-2 cell systems

Balimani, P, Patel, K., Marino, A., and Chong, S., Utility of 96 well Caco-2 cell system for increased throughput of P-gp screening in drug discovery, Eur. J. Pharmaceut. Biopharm., 58,99, 2004. 

Given the role of specific transporters for which prediction models are not (yet) available, the measurement of partitioning is necessary in many cases. For a number of situations systems are available to measure transport. One well-defined model for estimating the parameters for oral uptake is the Caco-2 cell system [30, 31]. Other systems exist for the blood-brain barrier [32] and the blood-placenta barrier [33]. 

Using the side-by-side diffusion cell system, Hidalgo et al. (1992) quantified the transflux of testosterone in Caco-2 monolayers at 37°C as a function of the flow rate of the 02/C02 gas mixture (Table 13). They concluded that the kinetics were ABL-controlled and proceeded to calculate the ABL thickness on each side of the diffusion chambers using... 

The known variability associated to the behavior of Caco-2 cell lines, together with the need to find a more robust and easy to grow type of culture led the pharmaceutical industry to substitute this system by, for example, MDCK cell cultures. So in silico modelers have also turned towards this new kind of in vitro cell data, although to a lesser extent than with Caco-2 systems. Perhaps the only notable example of the use of MDCK data is Refsgaard s categorical model, where a dataset of Caco-2 permeability values was enriched with MDCK permeability data [99]. 

However, this systems need further evaluation. For an industrial environment coculture systems need to be robust and reliable being at the same time easy to handle. On the other hand, convincing advantages have to be shown to change the monolayer system to a coculture model or to change the cell system used. In many companies CACO-2 cells are used since many years and an immense data base is available. 

PAMPA-biomimetic-Caco-2-comparison Several in vitro assays have been developed to evaluate the Gl absorption of compounds. Our aim was to compare three of these methods (/) the BAMPA method, which offers a HT, noncellular approach to the measurement of passive transport ( ) the traditional Caco-2 cell assay, the use of which as a HT tool is limited by the long cell differentiation time (21 days) and (// ) The BioCoat HTS Caco-2 assay system, which reduces Caco-2 cell differentiation to three days. The transport of known compounds (such as cephalexin, propranolol, or chlorothiazide) was studied at pH 7.4 and 6.5 in BAMPA and both Caco-2 cell models. Permeability data obtained was correlated to known values of human absorption. Best correlations (f= 0.9) were obtained at pH 6.5 for BAMPA and at pH 7.4 for the Caco-2 cells grown for 21 days. The Caco-2 BioCoat HTS Caco-2 assay system does not seem to be adequate for the prediction of absorption. The overall results indicate that BAMPA and the 21 -day Caco-2 system can be complementary for an accurate prediction of human intestinal absorption. 

With the difficulties associated with accurate estimation of permeability based only on physicochemical properties, a variety of methods of measuring permeability have been developed and used, among which are (l)cul-tured monolayer cell systems, such as Caco-2 or MDCK ( 2 diffusion cell systems that use small sections of intestinal mucosa between two chambers (3) in situ intestinal perfusion experiments performed in anesthetized animals such as rats and (4)intestinal perfusion studies performed in humans (40,54-62). All of these methods offer opportunities to study transport of drug across biological membranes under well-controlledconditions. Caco-2 mono-layer systems in particular have become increasingly commonly used in recent years and human intestinal perfusion methods are also becoming more commonly available. Correlations between Caco-2 permeability and absorption in humans have been developed in several laboratories (63-72). As shown in Fig. 

Caco-2Ceiis Brush Border Membrane Vesicles Epithelial Cell Model Isolated Intestinal Cells Non-Intestinal Cell Systems To determine mechanism an rate of drug passage arxl transport. 

In this in vitro system, the presence of serum in cell culture medium is not necessary, but the type of transwell is important (the total amount of H-triglycerides secreted was two-fold higher when using 3 pm versus 1 pm pore size transwells), and oleic acid supplementation is required for the formation and secretion of CMs as well as the transport of 3-carotene through Caco-2 cells. Finally, the presence of Tween 40 does not affect CM synthesis and secretion in this in vitro cell culture system. Thus, CMs secreted by Caco-2 cells were characterized as particles rich in newly synthesized H-triglycerides (90% of total secreted) containing apolipoprotein B (30% of total secreted) and H-phospholipids (20% of total secreted) and with an average diameter of 60 nm. These characteristics are close to those of CMs secreted in vivo by enterocytes. ... 

When screening for absorption by passive membrane permeability, artificial membranes have the advantage of offering a highly reproducible and high-throughput system. Artificial membranes have been compared to Caco-2 cells and for passive... 

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