ACTIVTox vs Primary Hepatocytes

Toxicity Expression of ACTIVTox Compared to Primary Hepatocytes

ACTIVTox, based on a patented human liver cell line (1), faithfully replicates results found using human primary hepatocytes. ACTIVTox circumvents the problems associated with primary hepatocytes as an experimental system.

Primary hepatocytes, from both rat and human, are widely used as a method to identify hepatotoxins and provide an in vitro system that is regarded as the closest approximation to the liver. As toxicity testing moves earlier in the discovery process and is viewed in the context of structure toxicity realtionships, a wider selection of structural variants needs to be profiled. This reveals two flaws in the use of primary hepatocytes as an experimental system. While animal cells are readily available, they often do not reflect human metabolism. Human cells are unavailable in the quality and quantity necessary for high throughput toxicity testing. ACTIVTox, based on a patented human liver cell line (1), circumvents these problems. Results presented here demonstrate that ACTIVTox faithfully replicates results found using human primary hepatocytes.

Procedure

Fifteen compounds with known human liver toxicity were chosen from the literature and tested using ACTIVTox. Using confluent, stationary cultures of ACTIVTox cells in 96 well plates, serial dilutions of the compounds were incubated in serum containing medium for 48 hrs. Aliqouts were removed for determination of lactate dehydrogenase release, an indicator of cell death. Results were collected in MDL Assay Explorer for determination of IC50s.

ACTIVTox IC50 correlates with IC50 determined in human primary hepatocytes

Figure 1 shows the correlation between IC50 determined in ACTIVTox versus values reported in the literature for fifteen known hepatotoxins. ACTIVTox yields essentially identical results.

There are several important features of this data. Several of these compounds, including aflatoxin B1 and diclofenac are metabolic toxins, requiring activation by the P450 system to exhibit toxicity (2). ACTIVTox determined IC50s identical to those found in primary hepatocytes. Tamoxifen, much less toxic in humans than in rats due to high rates of glucoronidation, is correctly identified here. HepG2, a widely used human liver cell line, does not accurately identify any of these compounds.

Figure 1. IC50 in ACTIVTox versus IC50 in Primary Hepatocytes. r2 = 0.96

List of compounds tested using ACTIVTox

Acetaminophen, Aflatoxin B1, Amiodarone, Acetylsalicylic Acid, Camptothecin, Cantharidin, Chelerythrine, Chlorpromazine, Diclofenac, Isoniazid, Ketoconazole, Quinidine, Sodium Valproate, Tacrine, Tamoxifen

More detailed information on this study or the individual compounds is available from Stem Cell Innovations.

References

1. Kelly, JH (1994) Permanent human hepatocyte cell line and its use in a liver assist device (LAD). US Patent No. 5,290,684.
2. Park, B.K., et al. (2005) The role of metabolic activation in drug-induced hepatotoxicity. Annu. Rev. Pharmacol. Toxicol. 45, 177 – 202.