Human HepaRG liver spheroids: cold storage protocol and study on pyridinium oxime-induced hepatotoxicity in vitro

Oximes play an essential role in the therapy of organophosphorus compound (OP) poisoning by reactivating inhibited acetylcholinesterase. Impairment of liver function was observed in OP poisoning and associated with obidoxime treatment by some reports. In this study human three-dimensional HepaRG spheroids were used as complex in vitro model to investigate oxime-induced liver toxicity. In this context, cold storage of liver spheroids at 4 degrees C in standard culture medium and in optimized tissue preservation solutions of up to 72 h was assessed. Cold storage in standard culture medium resulted in a complete loss of viability whereas an optimized tissue preservation solution preserved viability. Separately from that liver spheroids were exposed to the four oximes pralidoxime, obidoxime, HI-6, MMB-4 and cytotoxicity (effective concentration, EC50) was determined with an ATP-based assay at several time points. The release of aspartate aminotransferase (AST), alanine aminotransferase (ALT) and albumin secretion was measured in supernatants. The same parameters were assessed with diclofenac as positive hepatotoxic control and with the OP pesticides malathion and malaoxon alone or in the presence of obidoxime. All individual tested oximes and OP showed a low cytotoxicity with effective concentrations mostly >2,000 mu M. In contrast, the exposure to malaoxon in the presence of 1,000 mu M obidoxime resulted in a marked decrease of viability and an increased release of AST indicating risk of liver injury only if oxime antidotes are strongly overdosed.

Automated summary

Oximes-induced liver toxicity was examined using human three-dimensional HepaRG spheroids as a complex in vitro model. The results showed that cold storage at 4 degrees C preserved the viability of the liver spheroids in optimized tissue preservation solutions, but resulted in complete loss of viability in standard culture medium. In addition, it was found that there is a potential risk of liver injury when oxime antidotes are strongly overdosed.