Preparation and incubation of precision-cut liver and intestinal slices for application in drug metabolism and toxicity studies.

Precision-cut tissue slices (PCTS) are viable ex vivo explants of tissue with a reproducible, well defined thickness. They represent a mini-model of the organ under study and contain all cells of the tissue in their natural environment, leaving intercellular and cell-matrix interactions intact, and are therefore highly appropriate for studying multicellular processes. PCTS are mainly used to study the metabolism and toxicity of xenobiotics, but they are suitable for many other purposes.

Induction of metabolism and transport in human intestine: validation of precision-cut slices as a tool to study induction of drug metabolism in human intestine in vitro.

Induction of drug enzyme activity in the intestine can strongly determine plasma levels of drugs. It is therefore important to predict drug-drug interactions in human intestine in vitro. We evaluated the applicability of human intestinal precision-cut slices for induction studies in vitro.

In vitro methods to study intestinal drug metabolism.

Although the liver has long been thought to play the major role in drug metabolism, also the metabolic capacity of the intestine is more and more recognized. In vivo studies eventually pointed out not only the significance of first-pass metabolism by the intestinal wall for the bioavailability of several compounds, but also the relevance of transporters in this process. Only a few methods are available to study drug metabolism in vivo or in situ and with most of these methods it remains difficult to discriminate between the contribution of liver and extrahepatic tissues.

Innovative methods to study human intestinal drug metabolism in vitro: precision-cut slices compared with ussing chamber preparations.

Predictive in vitro methods to investigate drug metabolism in the human intestine using intact tissue are of high importance. Therefore, we studied the metabolic activity of human small intestinal and colon slices and compared it with the metabolic activity of the same human intestinal segments using the Ussing chamber technique. The metabolic activity was evaluated using substrates to both phase I and phase II reactions: testosterone, 7-hydroxycoumarin (7HC), and a mixture of cytochrome P450 (P450) substrates (midazolam, diclofenac, coumarin, and bufuralol).

Empirical validation of a rat in vitro organ slice model as a tool for in vivo clearance prediction.

Tissue slices have been shown to be a valuable tool to predict metabolism of novel drugs. However, besides the numerous advantages of their use for this purpose, some potential drawbacks also exist, including reported poor penetration of drugs into the inner cell layers of slices and loss of metabolic capacity during prolonged incubation, leading to underprediction of metabolic clearance. In the present study, we empirically identified (and quantified) sources of underprediction using rat tissue slices of lung, intestine, kidney, and liver and found that thin liver slices (+/-100 mum) metabolized model substrates (7-hydroxycoumarin, testosterone, warfarin, 7-ethoxycoumarin, midazolam, haloperidol, and quinidine) as rapidly as isolated hepatocytes.

Characterization of rat small intestinal and colon precision-cut slices as an in vitro system for drug metabolism and induction studies.

The aim of this study was to characterize rat small intestinal and colon tissue slices as a tool to study intestinal metabolism and to investigate gradients of drug metabolism along the intestinal tract as well as drug-induced inhibition and induction of biotransformation. Tissue morphology and the intestinal mucus layer remained intact in small intestinal and colon slices during 3 h of incubation, while alkaline phosphatase was retained and the rate of metabolism of three model compounds (7-hydroxycoumarin, 7-ethoxycoumarin, and testosterone) appeared constant. Phase I and phase II metabolic gradients, decreasing from stomach toward colon were shown to be clearly different for the model compounds used.