CORRELATION BETWEEN LIVER TEMPERATURE EMPLOYED DURING MACHINE PERFUSION AND REPERFUSION DAMAGE: ROLE OF Ca2+

This study compares the effects of machine perfusion (MP), at different temperatures, with simple cold storage. In addition, the role of Ca2+ levels in the MP medium was evaluated. MP: rat livers were perfused for 6 hrs using Krebs-Henseleit solution (KH) (with 1.25 or 2.5 mM CaCl2) at 4, 10, 20, 25, 30 and 37°C. Cold storage: liver were perfused in situ and preserved with Celsior solution at 4°C for 6 hrs. Reperfusion period (2 hrs at 37°C) was performed in the same conditions in MP and cold storage preserved livers. Hepatic enzyme release, bile production, ATP levels and morphology were evaluated during MP and reperfusion. MP at 37°C caused marked enzyme release; the same findings were obtained during reperfusion. By contrast, MP temperature lowering induced a significant decrease in liver damage. High levels of biliary gamma-glutamyltransferase and perfusate lactate-dehydrogenase were at MP 4°C and 10°C but not at MP 20°C. When KH-1,25 CaCl2 solution was used during MP at 20°C, very low enzyme release was observed and significantly lower hepatic damage was present at the end of the reperfusion period compared with cold storage. The same results were obtained when ruthenium red, a calcium uniporter blocker, was added to the KH-2.5 CaCl2. ATP levels were higher and morphology was better in liver preserved with KH-1,25 CaCl2. MP at 20°C with KH-1.25 CaCl2 results in better-quality liver preservation improving hepatocyte and endothelial biliary cell survival, compared with cold storage. This raises the need to reconsider the temperature and calcium levels to be used during liver MP.