Cold- and cryopreservation of dog liver and kidney slices

The use of tissue slices in culture could decrease the number of animals used in health-related research and decrease experimental variation. This reduction may come about particularly if the methods of cold- and cryopreserving tissue slices are perfected, and one can conduct sequential in vitro experiments into xenobiotic metabolism, organ-specific toxicity, or organ-specific biochemical processes with tissue slices. With this goal in mind, dog liver and kidney slices were placed in cold storage at 0°C using Viaspan (UW), Euro-Collins (EC), Sacks + prostacyclin (SP), and V-7 (V7) cold-preservation solutions for 10 days. Viability was assessed each day by measuring K⁺ content and protein synthesis after 4 h of incubation in Waymouth + 10% fetal calf serum (FCS). Dog liver slices can be cold-preserved in V7 for up to 7 days using K⁺ retention as the viability criterion but only up to 4 days using protein synthesis. Dog kidney slices can be cold-preserved in UW, EC, and V7 for up to 10 days using K⁺ retention, but only V7 could maintain protein synthesis for 10 days. Cryopreserved dog liver and kidney slices retained 63-68% of control viability after 4 h of incubation in FCS. The cryopreservation regimen included using 10% dimethyl sulfoxide in FCS as the cryoprotectant, a freezing rate of 0.5°C/min for liver slices and 12°C/min for kidney slices, and thawing in 37°C FCS. Continued development of cold- and cryopreserving tissue slices could reduce the numbers of animals used and provide accurate and reproducible data.