Accelerated Caco-2 cell permeability model for drug discovery

Introduction: By culturing Caco-2 cells according to a new and optimized protocol, it has been possible to accelerate the cell culture process in such a way that the cells can be used for experiments after only 6 days. The accelerated Caco-2 model has been compared to the traditional model (requiring 21-25 days of culture) in terms of tightness of the junctions, ability to rank chemical compounds for apparent permeability, active efflux and to discriminate P-gp substrates. Methods and results: In the new protocol, Caco-2 cells were cultured with the classical Caco-2 medium supplemented with puromycin. The initial cell seeding density was increased two times compared to the traditional procedure and the presence of a low concentration of puromycin in the culture medium reduced the Caco-2 permeability of mannitol. Bi-directional studies were performed with known P-gp substrates (rhodamine 123, digoxin and saquinavir) and with a total of 20 marketed drugs covering a wide range of physicochemical characteristics and therapeutic indications. Strong correlations were obtained between the apparent permeability in absorptive (Papp A -> B) or secretory (Papp B -> A) of the drugs in the accelerated model and in the traditional models and comparable efflux ratios were observed in the two studied models. Discussion: The new protocol reduces costs for screening and leads to higher throughput compared to traditional Caco-2 cell models. This accelerated model provides short time-feedback to the drug design during the early stage of drug discovery. (C) 2013 Elsevier Inc. All rights reserved.