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Hepatotoxicity and molecular aspects of hepatocyte function in primary culture
C Guguen-Guillouzo1, P Gripon, Y Vandenberghe
1Unité de Recherches Hépatologiques U 49 de l'INSERM, Hôpital de Pontchaillou, Rennes, France.
Abstract:
1. The application of primary cultures of hepatocytes in testing for hepatotoxicity of drugs is reviewed. 2. Hepatotoxicity results principally from the biotransformation of toxic agents. This process is very complex and specific and involves a powerful system of multigenic isozyme families for both phase I and phase II drug metabolizing reactions. Many of the isozymes are specifically expressed in the liver in relation to the maturation or differentiation state, and are specifically induced, possibly through a complex temporally programmed gene regulation. 3. This highly specific, coordinated, molecular regulation is difficult to maintain in vitro. Isolation of hepatocytes induces a prompt differential decline of liver-specific gene transcription, which leads to preferential loss of the most specific functions, including those of the drug metabolizing isozymes, whereas repair of cell damage remains active. 4. The use of serum-free, hormonally defined media stabilizes specific hepatic functions, but not transcriptional activity, for 4-5 days. Defined media retain active DNA replication but do not permit clonal growth of hepatocytes. Co-culturing hepatocytes with primitive biliary cells prolongs cell survival and their functional capacities for several weeks, including some of the transcriptional activity.
Insights
Primary hepatocyte cultures are crucial for drug hepatotoxicity testing. However, maintaining their specific liver functions in vitro is challenging due to rapid loss of gene transcription and drug-metabolizing enzymes.
Area of Science:
- Hepatology
- Toxicology
- Cell Biology
Background:
- Hepatotoxicity testing relies on primary hepatocyte cultures.
- Drug-induced liver injury stems from complex biotransformation by Phase I and II drug-metabolizing enzymes.
- Hepatocyte in vitro models struggle to replicate in vivo liver-specific gene expression and function.
Purpose of the Study:
- To review the application of primary hepatocyte cultures in drug hepatotoxicity assessment.
- To highlight the challenges in maintaining liver-specific functions and gene transcription in vitro.
- To discuss strategies for improving the stability and functionality of hepatocytes in culture.
Main Methods:
- Review of existing literature on hepatocyte culture and hepatotoxicity testing.
- Analysis of factors affecting liver-specific gene expression and function in vitro.
- Evaluation of culture media and co-culture systems for hepatocyte stabilization.
Main Results:
- Primary hepatocyte cultures are essential for evaluating drug hepatotoxicity.
- Hepatocyte isolation leads to a rapid decline in liver-specific gene transcription and drug-metabolizing enzyme activity.
- Serum-free defined media partially stabilize hepatic functions but not transcriptional activity.
- Co-culturing with biliary cells extends hepatocyte survival and function for weeks.
Conclusions:
- Maintaining the complex, coordinated molecular regulation of liver-specific functions in vitro remains a significant challenge.
- Serum-free defined media and co-culture systems offer improvements but do not fully replicate the in vivo environment.
- Further research is needed to optimize in vitro models for accurate and reliable hepatotoxicity prediction.