Optimal oxygen tension conditions for viability and functioning of precision-cut liver slices

Optimal oxygenation of culture media is important for the successful use of liver slices as an in vitro tool for studying liver function. For this reason the influence of 20, 40, 70 and 95% O2 concentration on the viability and metabolism of liver slices was investigated. The slices were incubated in the roller system at 37 degrees C under continuous gassing for 2, 24 and 48 hrs. Protein, DNA and potassium contents were maintained or even increased over time without influence by O2 concentrations. The albumin secretion of slices incubated at 40-95% O2 did not differ, but was much lower at 20% O2. A slight non-significant decrease in albumin secretion after 24 hrs of cultivation could be observed, whereas a much steeper decline was found in all groups after 48 hrs. Cytochrome P450 (CYP)-dependent 7-ethoxycoumarin O-deethylation (ECOD) did not differ between the various O2 concentrations, but declined from 2 to 48 hrs of incubation. It can be concluded that O2 concentration of 20% is not sufficient to maintain all cell functions of incubated rat liver slices, wheras 40, 70 and 95% are useful O2 concentrations to retain all parameters investigated.