Human Hepatocytes in Primary Culture: The Choice to Investigate Drug Metabolism in Man

Abstract

Different types of hepatic tissue, including whole or split livers from organ donors or waste liver from therapeutic liver resections, are used to prepare human hepatocyte cultures. Characteristics of liver samples from different origins (gender, age, healthy/pathological status, xenobiotic treatment) as sources of human hepatocytes are key factors which notably determine viability and functionality of hepatocytes. The characterisation of the CYP system can be assessed in terms of activity (using specific substrates/inhibitors), protein (antibody analysis) and molecular biology-based mRNA amplification techniques (PCR technology and DNA microarrays). It could reasonably be considered that human hepatocytes reflect the heterogeneity of CYP expression in human liver and is a suitable model for drug metabolism studies. Several key issues need to be addressed at the early stages of drug development to better select drug candidates (metabolic profile and rate, identification of CYPs involved, drug-drug interactions due to enzyme induction/inhibition). The metabolic stability and metabolite profile of new chemicals can be easily investigated by incubating the drugs with fully competent metabolic models like hepatocyte suspensions or 24 h-cultured hepatocytes. CYP inhibitory effects are usually screened in recombinant CYP enzymes or microsomes, however, the actual concentration of substrate and inhibitor available to the CYP enzyme depends on processes missing in subcellular models (transport mechanisms, cytosolic enzymes, binding to intracellular proteins). Since intact cells more closely reflect the environment to which drugs are exposed in the liver, cultured hepatocytes constitute a more predictive model for drug-drug interactions. Screening of CYP inducers cannot be done in microsomes as it requires a cellular system fully capable of expressing CYP genes. Primary hepatocytes are still the unique in vitro model for global examination of inductive potential of drugs (monitored as increases in mRNA content or activity).

The methyl ester of okadaic acid is more potent than okadaic acid in disrupting the actin cytoskeleton and metabolism of primary cultured hepatocytes

“…We have used hepatocytes here because the liver is clearly connected to the enteric system (Houten et al, 2006). Studying the effect of this toxin on hepatic cells is thus fundamental to a better understanding of the pharmacokinetics and pharmacodynamics of MeOk (Gomez-Lechon et al, 2004). In addition, hepatic cells have some characteristics very appropriate to our study, such as glucose uptake and the marked actin cytoskeletal structure (Oda et al, 2008).…”

Altered Drug Metabolism and Transport in Pathophysiological Conditions

“…Later studies have shown significant contribution of NAFLD (comprising of both, simple stage fatty liver as well as NASH) on expression and activity of DMEs in animals (Fisher et al, 2008(Fisher et al, , 2009a(Fisher et al, , 2009b. Similarly, in vitro studies in primary human or animal hepatocyte cell cultures from steatotic or non-steatotic livers showed a profound impact of steatosis on the metabolic functionality of hepatocytes (Donato et al, 2007;Fisher et al, 2004;Gomez-Lechon et al, 2004). Significant reductions in CYP1A2, 2C9, 2E1 and 3A4 activities in fat-overloaded hepatocytes were observed compared with control hepatocytes obtained from the same liver sample (Fisher et al, 2008).…”

Twenty-six years of HIV science: an overview of anti-HIV drugs metabolism

“…On the other hand, the use of hepatocyte cultures is limited by the restricted availability of liver tissue (Li et al, 1997;Gomez-Lechon et al, 2004). Liver-derived HepG-2 and BC2 cell lines and lung-derived line A549 have the disadvantage of expressing few enzymes, restricting their metabolic capacity (Yoshitomi et al, 2001;Le Vee et al, 2006).…”