title: Xenobiotic metabolizing enzyme activities in isolated and cryopreserved human liver parenchymal cells.
abstract: Liver parenchymal cells (hepatocytes) of human organ donors were isolated using a two-step collagenase perfusion technique. The average viability of the freshly isolated liver parenchymal cells, as judged by trypan blue exclusion, was 82% (SD = 7%; n = 6). The inter-individual differences in the determined enzyme activities were less than a factor of 7.5, despite the different sexes and ages of the donors. Freshly isolated parenchymal cells (PC) were cryopreserved using a computer-controlled freezing protocol. After thawing, cryopreserved cells had a mean viability of 57% (SD = 18%; n = 6). The activities of xenobiotic metabolizing enzymes in freshly isolated and cryopreserved cells were compared using PC from two donors. The enzyme activities of phenol sulfotransferase, 1-naphthol UDP-glucuronosyltransferase and microsomal epoxide hydrolase were well maintained after thawing (87-117% of activities in freshly isolated cells), whereas the activities of glutathione S-transferase, monitored with the broad spectrum substrate 1-chloro-2,4-dinitrobenzene, and the major broad spectrum cytosolic epoxide hydrolase were moderately but markedly reduced after cryopreservation (34-64% and 45-89% of levels in fresh cells, respectively). The decrease of both activities was dependent on the viability after thawing. When cryopreserved cells were purified by a Percoll centrifugation after thawing, the viability was increased from 62 to 92% for cells from one of the donors and from 88 to 98% for PC for the other donor. Subsequently the activity of glutathione S-transferase in Percoll-purified PC from the two donors was increased to 71 and 96% of levels in freshly isolated cells. It is concluded that the use of cryopreserved liver parenchymal cells of humans and other species represents a valuable tool in predicting which animal species best represents humans in hepatic metabolism and therefore should be the preferred species for investigations of metabolism and metabolism-dependent toxicities.
authors.affiliation: Institute of Toxicology, University of Mainz, Obere Zahlbacher Strasse 67, D-55131 Mainz, Germany.
authors.forename: B
authors.initials: B
authors.lastname: Diener
authors.forename: M
authors.initials: M
authors.lastname: Traiser
authors.forename: M
authors.initials: M
authors.lastname: Arand
authors.forename: J
authors.initials: J
authors.lastname: Leissner
authors.forename: U
authors.initials: U
authors.lastname: Witsch
authors.forename: R
authors.initials: R
authors.lastname: Hohenfellner
authors.forename: F
authors.initials: F
authors.lastname: Fändrich
authors.forename: I
authors.initials: I
authors.lastname: Vogel
authors.forename: D
authors.initials: D
authors.lastname: Utesch
authors.forename: F
authors.initials: F
authors.lastname: Oesch