Development of 3D-cultured spheroid model using human renal proximal tubule epithelial cells for drug discovery

Abstract

Primary human kidney cells or kidney-derived cell lines do not maintain the gene expression of drug transporters. Conventional kidney cells have not yet been used in drug discovery. In animal studies, low predictivity to the clinical trial, species difference and animal welfare are always issues. Therefore, it is desired to commercialize the human kidney cells that can be used for drug discovery screening and analysis of the mechanism. Recently, highly functional kidney cells have been investigated, including the iPS cell-derived kidney organoids and the application to the Micro Physiological System. In this study, we investigated the usefulness of evaluating drug-induced kidney injury (DIKI) using 3D-cultured renal proximal tubule epithelial cells (3D-RPTEC, Nikkiso), whose expression of drug transporters and endocytosis receptors are comparable to those of human kidney cortex.

The intracellular ATP content in 3D-RPTEC was reduced by the exposure of tenofovir that is a substrate of OAT. On the other hand, ATP reduction by tenofovir was not observed in the 2D-cultured RPTEC. These results suggested that the expression of drug transporters was required for the evaluation of DIKI. In addition, over 30 drugs were exposed to 3D-RPTEC for 7 days, and the deviation between the concentration causing 20% reduction in intracellular ATP level and the effective plasma concentration was calculated as the safety margin of DIKI. The prediction of DIKI was judged if a safety margin is less than 100 times. As a result, the sensitivity was about 80% and the specificity was more than 90%. Furthermore, we investigated the usefulness of High Content Analysis using a confocal image cytometer that is used to analyze toxicity mechanisms.

In this study, we would like to introduce the application of 3D-RPTEC for drug discovery and the evaluation of oligonucleotide therapeutics.