Cell bead based three-dimensional (3D) hepatic model toward high throughput drug-induced toxicity screening

For several decades, hepatotoxicity has been a major issue for drug development.Recently, three-dimensional (3D) cell culture has been believed to improve cell drug response accuracy. However important limitations such as slow production, lack of cell density control and lack of cell-extracellular matrix (ECM) interactions are still remaining in the current systems. We believe that cell culture on collagen gel microbeads, developed by Takeuchiʼs group, could overcome these limitations. Thus, in this study, we evaluated the implementation of this cell culture system as a potential model for druginduced toxicity screening. Using HepG2 cell line, we showed that cells grown on collagen microbeads significantly up-regulate drug metabolism specific genes, i.e. CYP enzymes, very soon after seeding, compared to monolayer culture, whereas spheroid cultures show an up-regulation from 48 hours only. Moreover, after having incubated HepG2 cells grown in monolayer, in spheroid, and on collagen microbeads with acetaminophen for 24 hours, we detected higher cell sensitivity to the compound in the collagen microbeads culture condition. Thus, we suggest this culture system to be a promising in-vitro hepatic model for pharmaceutical drug toxicology screening. Finally, as we believe that integrated cell-based microchips are the future of drug screening and development, we will then try to design an arraying system able to combine single cell bead culture and localized drug perfusion to demonstrate cell bead culture systemʼs practical application in high throughput screening.