Cryopreservation of rat and human liver slices by rapid freezing

The cryopreservation of human li,;er slices is a promising way to enhance t he ability to test the metabolism of drug candidates. This study demonstrat es the use of a novel technique for the cryopreservation of both rat and hu man liver slices. In this technique the slices are treated with Me2SO and s andwiched between aluminum plates separated by a thin gasket. The device is then submerged in liquid nitrogen to freeze the slices. which can then be stored until use, To thaw the slices, the apparatus is submerged in a water bath at 37 degrees C. Slices frozen and thawed in this manner were compare d to those frozen in conventional cryovials. The viability of the slices wa s determined by incubating them in 12-well plates and measuring urea synthe sis. ethoxycoumarin metabolism and cytosolic enzyme leakage (LDH and ALT). The viability of mt slices frozen between plates approached that of fresh s lices and was consistently higher than slices frozen in cryovials. Slices f rom two human samples gave similar results. The technique was found to work over a wide range of Me2SO concentrations (4.5 to 22% was tested) with an optimal concentration between 10 and 15%. (C) 1999 Academic Press.