Cryopreservation of Rat and Monkey Liver Slices

Abstract

A method for the long-term storage of liver slices by cryopreservation was developed. The viability of liver slices was determined by analysing the leakage of alanine aminotransferase, urea production, and the metabolism of testosterone. Rat liver slices were found to be optimally cryopreserved by exposure for 30 minutes to 12% dimethyl sulphoxide (v/v) at 2°C before freezing. Subsequent direct immersion in liquid nitrogen was more effective than a cooling rate of ±1°C/mmute, which reduced viability. Storage at a temperature of -80°C lowered viability compared to storage at -196°C. These conditions for optimal cryopreservation were used to cryopreserve rat, rhesus monkey and cynomolgus monkey liver slices. The viability of these liver slices was maintained at: 74%, 86% and 85%, respectively, when alanine aminotransferase content was measured; 80%, 109% and 82%, respectively, when urea production was measured; and 109%, 60% and 85%, respectively, when the metabolism of testosterone was measured. Viability was maintained for at least one month. The results show that, by using the method presented here, liver slices from these species can be stored while maintaining viabilities similar to initial values. This method will facilitate the optimal use of liver slices and reduce the number of experimental animals used.