Human monocyte-derived cells with individual hepatocyte characteristics: a novel tool for personalized in vitro studies

Abstract

Gender, ethnicity and individual differences in hepatic metabolism have major impact on individual drug response, adverse events and attrition rate during drug development. Therefore, there is an urgent need for reliable test systems based on human cells. Yet, the use of primary human hepatocytes (PHHs) is restricted by limited availability, invasive preparation and short-term stability in culture. All other cellular approaches proposed so far have major disadvantages. We investigated whether peripheral human monocytes after cultivation according to our novel protocol (monocyte-derived hepatocyte-like cells (MH cells)) can serve as an in vitro model for hepatocyte metabolism. Enzyme activities, synthesis parameters (coagulation factor VII and urea) and cytochrome (CY) P450 activities and induction were investigated. Furthermore, MH cells were compared with PHH from the same donor. Using our protocol, we could generate cells that exhibit hepatocyte-like properties: These cells show 71±9% of specific ALT activity, 41±3% of CYP3A4 activity and 65±13% of factor VII secretion when compared with PHHs. Consequently, CYP-mediated acetaminophen toxicity and drug interactions could be shown. Moreover, the investigated parameters were stable in culture over at least 4 weeks. Furthermore, MH cells retain gender-specific and donor-specific CYP activities and toxicity profiles, respectively. MH cells show quantitative and qualitative approximation to human hepatocytes concerning CYP-metabolism and toxicity. Our data support individual prediction of toxicity and CYP metabolism. MH cells are a novel tool to investigate long-term hepatic toxicity, metabolism and drug interactions. The liver is an important site of drug metabolism and hepatocytes are mainly responsible for toxification and detoxification of substances. A huge array of enzymes and transporters allows the hepatocyte to metabolize, conjugate and finally excrete xenobiotics and endobiotics. The first step, also referred to as phase-I metabolism, is performed predominantly by enzymes of the cytochrome P450 (CYP450) enzyme family. The CYPs 1A2, 2A6, 2B6, 2D6, 2E1, 3A4 and 3A5 are found in hepatocytes with great abundance. 1 Most CYP enzymes can be induced, that is, their activity in the hepatocyte is increased to manage greater amounts of xenobiotics. This induction is mediated by receptors, such as the pregnane-X-receptor (PXR), 2 the aryl-hydrocarbon receptor 3 and the constitutive androestendione receptor. 1 Knowing the way a substance is metabolized and how a substance interacts with co-medication is crucial for modern drug design. Therefore, hepatocyte models are urgently needed for drug development, because no other cell possesses a comparable equipment of metabolism pathways. The complexity of this system is augmented by different activities of CYP enzymes dependent on sex, age, ethnicity and individual factors, including co-medication. [4][5][6][7] Pharmacogenomics is a powerful tool to identify different individual metabolism patterns, 8 yet this method only d...

Monocyte-derived hepatocyte-like cells for causality assessment of idiosyncratic drug-induced liver injury

“…The toxicity induced in MH cells derived from patients with iDILI by the suspected causative agents could be due to the individual metabolic capabilities of these cells 26. Current concepts of iDILI suggest that altered dose response could lead to subclinical hepatocyte damage triggering an immune response that most likely determines the severity of the injury.…”

“…We therefore have developed a standardised method to generate monocyte-derived hepatocyte-like (MH) cells, which exhibit several donor specific hepatocyte characteristics: MH cells are derived from peripheral monocytes and retain several of their characteristics (eg, low level expression of CD14). Additionally, MH cells show inducible activities of CYP450 enzymes 1A2, 2C9, 3A4 reflecting the activities in primary human hepatocytes of the same donor 26. Additional data on phase II metabolism as uridine diphosphate (UDP)-glucuronosyltransferase activity as well as expression of several sulfotransferases and glutathione-S-transferases have been obtained.…”

“…Acute liver injury was defined26 as elevation of alanine aminotransferase activity (ALT) ≥5×ULN (upper limit normal), alkaline phosphatase activity (AP) ≥2×ULN or ALT ≥3×ULN accompanied by total bilirubin (Bili) ≥2×ULN. After informed consent of the patients, data on gender, age, ethnicity, height, weight, alcohol and nicotine consumption as well as the results of the clinical investigations were recorded in order to comply with recommendations from expert consensus meetings 28 29.…”

“…MH cells were generated as described 26. MH cells of healthy donors were generated from residual blood that could be obtained anonymously after thrombocyte donation in the department of transfusion medicine, University Hospital Munich.…”

Drug-Induced Liver Injury and Individual Cell Models

“…Thus, in the view of the rare incidence of idiosyncratic DILI, huge numbers of tests would be required to exclude the risk of idiosyncratic DILI. Therefore, we have developed MetaHeps, a cell model that is generated from peripheral monocytes without genetic modifications [9] . Our data provide evidence that MetaHeps show several characteristics of hepatocytes necessary for the investigation of drug hepatotoxicity in vitro.…”