Relevance of the incubation period in cytotoxicity testing with primary human hepatocytes
- 73 Downloads
Primary human hepatocytes (PHHs) remain the gold standard for in vitro testing in the field of pharmacology and toxicology. One crucial parameter influencing the results of in vitro tests is the incubation period with test compounds. It has been suggested that longer incubation periods may be critical for the prediction of repeated dose toxicity. However, a study that systematically analyzes the relationship between incubation period and cytotoxicity in PHHs is not available. To close this gap, 30 compounds were tested in a concentration-dependent manner for cytotoxicity in cultivated cryopreserved PHHs (three donors per compound) for 1, 2 and 7 days. The median of the EC50 values of all compounds decreased 1.78-fold on day 2 compared to day 1, and 1.89-fold on day 7 compared to day 1. Median values of EC50 ratios of all compounds at day 2 and day 7 were close to one but for individual compounds the ratio increased up to almost six. Strong correlations were obtained for EC50 on day 1 and day 7 (R = 0.985; 95% CI 0.960–0.994), day 1 and day 2 (R = 0.964; 95% CI 0.910–0.986), as well as day 2 and day 7 (R = 0.981; 95% CI 0.955–0.992). However, compound specific differences also occurred. Whereas, for example, busulfan showed a relatively strong increase on day 7 compared to day 1, cytotoxicity of acetaminophen did not increase during longer incubation periods. To validate the observed correlations, a publicly available data set, containing data on the cytotoxicity of human hepatocytes cultivated as spheroids for incubation periods of 5 and 14 days, was analyzed. A high correlation coefficient of EC50 values at day 5 and day 14 was obtained (R = 0.894; 95% CI 0.798–0.945). In conclusion, the median cytotoxicity of the test compounds increased between 1 and 2 days of incubation, with no or only a minimal further increase until day 7. It remains to be studied whether the different results obtained for some individual compounds after longer exposure periods would correspond better to human-repeated dose toxicity.
KeywordsHepatotoxicity Primary human hepatocyte Incubation period Cell-titer-blue
Drug-induced liver injury
- Vit C
The study was supported by the European Union’s Horizon 2020 research and innovation programme (EUToxRisk; no. 681002) with additional contributions of the projects StemCellNet (BMBF, 01EK1604A), Liver Simulator (BMBF, 031A355A), DILI (BMBF, 031L0074F), LiSyM (BMBF, 031Loo45), LivSysTransfer (BMBF, 0101-31Q0517), InnoSysTox (BMBF/EU, 031L0021A), SteatoTox (031L0114B) and DEEP (BMBF, 01KU1216).
Compliance with ethical standards
Conflict of interest
There is no conflict of interest.
- Godoy P, Hewitt NJ, Albrecht U et al (2013) Recent advances in 2D and 3D in vitro systems using primary hepatocytes, alternative hepatocyte sources and non-parenchymal liver cells and their use in investigating mechanisms of hepatotoxicity, cell signaling and ADME. Arch Toxicol 87(8):1315–1530CrossRefGoogle Scholar
- Grinberg M (2017) Statistical analysis of concentration-dependent, high-dimensional gene expression data. PhD thesis, University of Dortmund, 2017Google Scholar
- Hewitt NJ, Lechon MJ, Houston JB et al (2007) Primary hepatocytes: current understanding of the regulation of metabolic enzymes and transporter proteins, and pharmaceutical practice for the use of hepatocytes in metabolism, enzyme induction, transporter, clearance, and hepatotoxicity studies. Drug Metab Rev 39(1):159–234CrossRefGoogle Scholar