Phase I and phase II metabolic activities are retained in liver slices from mouse, rat, dog, monkey and human after cryopreservation.

Precision-cut liver slices are described as a valuable tool for in vitro metabolism studies of potential drug candidates. Recently, some papers reported successful cryopreservation conditions for liver slices, facilitating a broader and more efficient use of the tissue (particularly of human origin). The aim of this study is to evaluate the effect of cryopreservation on both phase I and phase II metabolism in liver slices prepared from mouse, rat, dog, monkey and human, using rapid freezing in the presence of 18% DMSO. Glucuronidation and sulfation activities (phase II) in both freshly prepared and cryopreserved liver slices were determined by rapid LC-MS/MS analyses using 7-hydroxycoumarin as a marker substrate. Testosterone was used as a marker substrate for cytochrome P450 mediated drug metabolism (phase I). Although the metabolic patterns and rates varied among the different species, the phase I and phase II metabolic capacities of the liver slices were well maintained after cryopreservation. Despite the good biotransformation capacity of cryopreserved slices a decrease in viability, expressed as ATP content and LDH leakage, was observed. MTT reduction was well maintained after cryopreservation. The possibility to cryopreserve liver slices will allow a more efficient utilisation of tissue, in particular from human, but also from dog and monkey. Finally, cryopreserved liver slices from mouse, rat, dog, monkey and human with good phase I and II metabolism activities are a useful in vitro tool to compare metabolite profiles of new chemical entities between species.