Expression levels of drug-metabolizing enzyme, transporter, and nuclear receptor mRNAs in a novel three-dimensional culture system for human hepatocytes using micro-space plates.

We evaluated a novel three-dimensional primary culture system using micro-space plates to determine the expression levels of 61 target (drug-metabolizing enzymes, transporters, and nuclear receptors) mRNAs in human hepatocytes. We measured mRNA expression levels of many target genes in four lots of cryopreserved human hepatocyte primary cells after 120 h of culture and compared differences in mRNA expression levels between cultures using traditional plates and those using micro-space plates. In this study, we show that the mRNA levels of many experimental targets in human hepatocytes before inoculation resemble the levels inside the human liver. Furthermore, we show that the rate of change of expression levels of many target mRNAs relative to the value before inoculation of the hepatocytes into micro-space plates was relatively smaller than the rate of change in hepatocytes inoculated into traditional plates. Pharmacokinetics-related examinations using this system are possible within a time frame of 120 h. We report that this novel three-dimensional culture system reproduces mRNA expression levels that are nearer to those in the liver in vivo and is an excellent platform for maintaining mRNA expression levels of drug-metabolizing enzymes and transporters when compared to common monolayer cultures.