ABSTRACT
We developed a novel technique of subnormothermic ex vivo liver perfusion (SNEVLP) for the storage of liver grafts before transplantation. To test the safety of SNEVLP for the nonextended criteria grafts (standard grafts), we compared it to a control group with minimal cold static storage (CS) time. Heart-beating pig liver retrieval was performed. Grafts were either stored in cold unmodified University of Wisconsin solution (CS-1), in cold University of Wisconsin solution with ex vivo perfusion additives (CS-2), or preserved with a sequence of 3 hours CS and 3 hours SNEVLP (33°C), followed by orthotopic liver transplantation. Liver function tests and histology were investigated. Aspartate aminotransferase (AST) levels during SNEVLP remained stable (54.3 ± 12.6 U/L at 1 hour to 47.0 ± 31.9 U/L at 3 hours). Posttransplantation, SNEVLP versus CS-1 livers had decreased AST levels (peak at day 1, 1081.9 ± 788.5 versus 1546.7 ± 509.3 U/L; P = 0.14; at day 2, 316.7 ± 188.1 versus 948.2 ± 740.9 U/L; P = 0.04) and alkaline phosphatase levels (peak at day 1, 150.4 ± 19.3 versus 203.7 ± 33.6 U/L; P = 0.003). Bilirubin levels were constantly within the physiological range in the SNEVLP group, whereas the CS-1 group presented a large standard deviation, including pathologically increased values. Hyaluronic acid as a marker of endothelial cell (EC) function was markedly improved by SNEVLP during the early posttransplant phase (5 hours posttransplant, 1172.75 ± 598.5 versus 5540.5 ± 2755.4 ng/mL). Peak international normalized ratio was similar between SNEVLP and CS-1 groups after transplantation. Immunohistochemistry for cleaved caspase 3 demonstrated more apoptotic sinusoidal cells in the CS-1 group when compared to SNEVLP grafts 2 hours after reperfusion (19.4 ± 19.5 versus 133.2 ± 48.8 cells/high-power field; P = 0.002). Adding normothermic CS-2 had no impact on liver injury or function after transplantation when compared to CS-1. In conclusion, SNEVLP is safe to use for standard donor grafts and is associated with improved EC and bile duct injury even in grafts with minimal CS time.
