Rat renal cortical slices: Maintenance of viability and use in in vitro nephrotoxicity testing

The majority of in vitro toxicology studies employing precision-cut rat renal slices are carried out using simple incubation systems over relatively short periods of time (usually up to 8 hr). We aimed to develop a system for longer-term (up to 24 hr) culture of rat renal slices. The viability of precision-cut rat renal cortical slices was therefore investigated under a variety of incubation conditions. Slices cultured using a dynamic organ culture system were found to be more viable than those cultured in shaken multiwell dishes. This improved viability was evident after only 2 hr of culture (as assessed by the measurement of LDH leakage). An oxygen enriched gaseous environment was found to be important for the maintenance of slice viability using the dynamic organ culture system and conditions were established which permitted the culture of viable slices for periods up to 24 hr. Using these optimized incubation conditions, less than 8% LDH leakage was observed at 24 hr and slices retained 84% of fresh ATP values. Histologically, few signs of slice degeneration were noted until 20 hr of culture. The renal slice system was shown to discriminate between the most toxic and least toxic of a series of cephalosporin antibiotics, based on measurements of slice ATP content.