Transport Caco-2 cells

P-gp substrate 22 substrates and 31 nonsubstrates 115 substrates and 157 nonsubstrates 61% substrates and 81% nonsubstrates correctly predicted. Overall accuracy 72.4% Transport Caco-2 cell line Size, shape (e.g. molecular surface and glo-bularity), hydrophilic and H-bonding related descriptors correlated positively with P-gp activity, log P0/w not significant [54]... 

The IC50 and of transporter inhibitors can be determined using selective transporter substrate by in vitro assays. For uptake transporters, hepatocyte, transporter transfected cells, oocytes, and yeast have been used as in vitro models for efflux transporter, Caco-2 cells, and transporter transfected cells and membranes are commonly used models. 

Accumulation in urine, resulting in a relatively constant plateau concentration over a time-period of about 3 h, can be related to several important interplaying mechanisms. Both, PAMPA and transport through a Caco-2 cell monolayer predicted high (log Pg -4.8 cm s ) to moderate (Papp.a b 6.4 x 10 cm s . Table 1) permeability for 42f. Although 42f is a substrate of efflux transporters (Caco-2 cell experiment b-a/a-b ratio >2, Table 1), the efflux transporters [e.g. P-gp) can be saturated by the applied high dose of 10 mg Once in circu-... 

Woodcock, S., Williamson, I., Hassan, I., MacKay, M., Isolation and characterization of clones from the Caco-2 cell line displaying increased taurocholic add transport, J. Cell Sd. 1991, 98, 323-332. 

Studies were undertaken to quantify transporters and examine regional expression in the intestine. mRNA levels in the gut were studied by Englund et al. [35]. Nine transporters were examined and eight were shown to have significant regional differences in expression. In addition, up to a 20-fold difference in expression was observed for certain transporters between intestinal tissue and Caco-2 cells. Expression of transporters in cell models compared to normal tissue can be markedly different, depending on the age of the cells, passage number and culture conditions [35]. Cell models may under- or overexpress transporters. In addition cell lines may express transporters which may not be relevant in vivo. 

Usually, PAMPA does not have any aqueous pores and is therefore not suitable for examining paracellular transport. Some cell models, for example, Caco-2 and MDCK, have a narrower tight junction than the in vivo human intestine and may underestimate paracellular transport. However, the contribution of the paracellular pathway can be added using an in silico approach [76-78]. 

In order to effectively assess drug transport, a cell line must form polarized monolayers of differentiated enterocytes. In addition, the cells must retain the morphological and biochemical characteristics of the human intestine.8,9 Primary cultures of human enterocytes have low viability and do not differentiate or form monolayers.10 Immortalized cell lines have been developed with mixed results.11 The Caco-2 cell fine, derived from a human colon carcinoma, is the cell culture... 

Snyder NJ, Tabas LB, Berry DM, Duckworth DC, Spry DO and Dantzig AH. Structure-activity relationship of carbacephalosporins and cephalosporins antibacterial activity and interaction with the intestinal proton-dependent dipeptide transport carrier of Caco-2 cells. Antimicrob Agents Chemother 1997 41 1649-57. 

MANNA c, GALLETTi p, MAISTO G, cucciOLLA V, d angelo s, zappia V (2000) Transport mechanism and metabolism of olive oil hydroxytyrosol in Caco-2 cells. FEBS Lett. 470 341-4. 

OITATE M, NAKAKI R, KOYABU N, TAKANAGA H, MATSUO H, OHTANI H, SAWADA Y (2001) TranSCellular transport of genistein, a soybean-derived isoflavone, across human colon carcinoma cell line (Caco-2). Biopharm Drug Dispos. 22 23-9. 

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. ... 

Caco-2 cells and ezetimibe, a potent inhibitor of chloresterol absorption in humans, it was reported that (1) carotenoid transport was inhibited by ezetimibe up to 50% and the extent of that inhibition diminished with increasing polarity of the carotenoid molecule, (2) the inhibitory effects of ezetimibe and the antibody against SR-BI on P-carotene transport were additive, and (3) ezetimibe may interact physically with cholesterol transporters as previously suggested - and also down-regulate the gene expression of three surface receptors, SR-BI, NPCILI, and ABCAl. 

Reboul, E. et al.. Lutein transport by Caco-2 TC-7 cells occurs partly by a facilitated process involving the scavenger receptor class B type 1 (SR-Bl), Biochem. J., 387, 455, 2005. 

During, A., Dawson, H.D., and Harrison, E.H., Carotenoid transport is decreased and expression of the lipid transporters SR-Bl, NPCILI, and ABCAl is down-regulated in Caco-2 cells treated with ezetimibe, J. Nutr., 135, 2305, 2005. 

The importance of drug ionization using cell-based methods such as Caco-2 in the in vitro prediction of in vivo absorption was discussed [45]. It was observed that when the apical pH used in Caco-2 studies was lowered from 7.4 to 6.0 a better correlation was obtained with in vivo data, demonstrating that careful selection of experimental conditions in vitro is crucial to produce a reUable model. Studies with Caco-2 monolayers also suggested that the ionic species might contribute considerably to overall drug transport [46]. 

Camenisch, G., Folkers, G., Van de Waterbeemd, H. Comparison of passive drug transport through Caco-2 cells and artificial membranes. Int. J. Pharm. 1997, 147, 61-70. 

The evaluation of the apparent ionization constants (i) can indicate in partition experiments the extent to which a charged form of the drug partitions into the octanol or liposome bilayer domains, (ii) can indicate in solubility measurements, the presence of aggregates in saturated solutions and whether the aggregates are ionized or neutral and the extent to which salts of dmgs form, and (iii) can indicate in permeability measurements, whether the aqueous boundary layer adjacent to the membrane barrier, Umits the transport of drugs across artificial phospholipid membranes [parallel artificial membrane permeation assay (PAMPA)] or across monolayers of cultured cells [Caco-2, Madin-Darby canine kidney (MDCK), etc.]. 

Yamashita et al. [82] also studied the effect of BSA on transport properties in Caco-2 assays. They observed that the permeability of highly lipophilic molecules could be rate limited by the process of desorption off the cell surface into the receiving solution, due to high membrane retention and very low water solubility. They recommended using serum proteins in the acceptor compartment when lipophilic molecules are assayed (which is a common circumstance in discovery settings). 

Yamashita et al. [82] added up to 10 mM taurocholic acid, cholic acid (cmc 2.5 mM), or sodium laurel sulfate (SLS low ionic strength cmc 8.2 mM) to the donating solutions in Caco-2 assays. The two bile acids did not interfere in the transport of dexamethasone. However, SLS caused the Caco-2 cell junctions to become leakier, even at the sub-CMC 1 mM level. Also, the permeability of dexamethasone decreased at 10 mM SLS. 

Artursson, R, Epithelial transport of drugs in cell culture. I A model for studying the passive diffusion of drugs over intestinal absorptive (Caco-2) cells, J. Pharm. Sci. 79, 476-482 (1990). 

Hilgers, A. R. Conradi, R. A. Burton, P. S., Caco-2 cell monolayers as a model for drug transport across the intestinal mucosa, Pharm. Res. 7, 902-910 (1990). 

Hilgendorf, C. Spahn-Langguth,H. Regardh,C. G. Lipka, E. Amidon,G. L. Langguth, P., Caco-2 vs Caco-2/HT29-MTX co-cultured cell lines Permeabilities via diffusion, inside- and outside-directed carrier-mediated transport, J. Pharm. Sci. 89, 63-75 (2000). 

G Wilson, IF Hassan, CJ Dix, I Williamson, R Shah, M Mackay. Transport and permeability properties of human Caco-2 cells An in vitro model of the intestinal epithelial cell barrier. J Controlled Release 11 25-40, 1990. 

Buur A, N Mprk. (1992). Metabolism of testosterone during in vitro transport across Caco-2 cell monolayers Evidence for beta-hydroxysteroid dehydrogenase activity in differentiated Caco-2 cells. Pharm Res 9 1290-1294. 

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