A novel in vitro permeability assay using three-dimensional cell culture system.

Three-dimensional (3D) cell culture systems are well-known to better represent the in vivo environment and they are applied to many areas of research. Spheroid model is one of the systems of 3D cell culture and here in our research, a permeability assay utilizing the spheroids was developed. Number of cells forming the spheroids, initial compound concentration, and incubation time were optimized to provide the best assay performance. After development of the assay, it was evaluated with 22 commercially available compounds. The developed Caco-2 3D spheroid permeability assay demonstrated a reasonable correlation with human absorption values. The parallel artificial membrane permeability assay (PAMPA) was also performed for the same set of compounds and the results were compared with those of the 3D permeability assay. The correlation with human absorption values was shown to be improved with the 3D permeability assay. The successful development of the Caco-2 3D spheroid permeability assay also suggests the potential application of the 3D cell culture systems to other areas of pharmacokinetic research.