Table 2.
Experimental and clinical studies of machine perfusion of extended criteria donor liver grafts.
| Studies | Model | Primary graft condition, N | MP time | Results and immunological aspects |
|---|---|---|---|---|
| ANIMAL STUDIES | ||||
| Lee et al. (54) | Rats HMP vs. SCS followed by 1 h machine reperfusion | DCD; N = n.d. WIT: 30 min |
10 h | HMP for 10 h improved both function and microcirculation while reducing cellular damage of liver tissue when compared with SCS |
| Lauschke et al. (55) | Rats HMP with HTK vs. Belzer's solution vs. SCS followed by 45 min machine reperfusion | DCD; N ≥ 5/group WIT: 1 h |
24 h | HLA class II antigen expression was detected on post-sinusoidal venular endothelium after SCS of DCD livers, while the antigen was almost absent or markedly reduced after HMP with HTK or Belzer's solution, respectively |
| Lee et al. (56) | Rats HMP vs. SCS with Tx | DCD; N = 7/group WIT: 30 min |
5 h | HMP improved survival and reduced cellular damage of liver tissue that has experienced 30 min of WIT when compared with SCS tissues |
| Bessems et al. (57) | Rats HMP with Polysol or UW-G vs. SCS followed by 1 h machine reperfusion | DCD; N = 6/group WIT: 30 min |
24 h | 24 h HMP of DCD rat livers using the newly developed preservation solution Polysol results in less hepatocellular damage and better liver function compared to SCS in UW or HMP using UW-G |
| Manekeller et al. (58) | Rats HMP vs. SCS followed by 2 h machine reperfusion | DCD; N ≥ 5/group WIT: 30 min CIT: 16 |
0.5, 1, 2, and 3 h | 1 h of post-conditioning after a long time (16 h) of SCS organs improved the viability and sustainability. The significantly higher ATP content and the lack of apoptotic signs in the tissue were observed |
| Nagrath et al. (59) | Rats NMP ± defatting agent cocktail without Tx | Steatotic livers, N = 7 vs. 5 | 3 h | Perfusate supplementation with defatting agents significantly reduced the intracellular fat content of perfused livers within a few hours |
| Olschewski et al. (60) | Rats HMP vs. SNMP vs. SCS without Tx |
DCD; N = 5/group WIT: 1 h |
6 h | In contrast to preservation at 4 or 12°C MP at 21°C has a beneficial positive effect on the initial organ function, structural integrity of the sinusoidal endothelium, and hepatocellular damage |
| Stegemann et al. (61, 62) | Rats HMP with different perfusion solutions vs. gaseous oxygen persufflation vs. SCS without Tx | DCD; N = 6/group WIT: 30 min |
18 h | The use of Custodiol-N solution led to a significantly decreased release of ALT or LDH during HMP and reperfusion compared with HTK solution and reduced the level of apoptosis. The use of gaseous oxygen persufflation improved the tissue integrity and functional recovery of predamaged livers |
| Jamieson et al. (63) | Porcine NMP without Tx | Steatotic and normal livers, N = 3 vs. 5 WIT: 16 ± 4 min CIT: 76 ± 11 min |
48 h | Steatotic livers can be successfully preserved using NMP for prolonged periods, and NMP facilitates a reduction in hepatic steatosis |
| Ferrigno et al. (30) | Rats SNMP vs. SCS followed by 2 h machine reperfusion | DCD; N = 5/group WIT: 30 min |
6 h | MP preservation at 20°C improves cellular survival reducing the mitochondrial function in livers obtained from DCDs as compared with SCS |
| Gringeri et al. (31) | Porcine SNMP vs. SCS followed by 2 h machine reperfusion | DCD; N = 5/group WIT: 1 h |
6 h | The SNMP group showed better histopathologic results with significantly less hepatic damage compared with SCS |
| Schlegel et al. (29) | Rats HOPE vs. SCS with Tx | DCD; N = 20/group WIT: 30 min CIT: 4 h |
1 h | HOPE treatment significantly decreased IRI of hepatocytes by reducing the activation of Kupffer cells and endothelial cells. Moreover, HOPE-treated DCD livers were protected from activation of the innate immunity according to a decreased IRI |
| Schlegel et al. (64) | Porcine HMP with different parameters vs. SCS without Tx | DCD; N = 8/group WIT: 1 h CIT: 6 h |
1 h | HOPE protected from mitochondrial and nuclear IRI by downregulation of the mitochondrial activity before reperfusion. Cold perfusion itself, under low-pressure conditions, prevented endothelial damage independently of oxygen |
| Izamis et al. (65) | Rats NMP with Tx | WIT: 0 vs. 1 h N = 11 vs. 7 |
5 h | MP suppressed lipid oxidation, likely due to the high insulin levels. Perfused livers did not consume all the available oxygen and were hypoxic independent of ischemic injury, suggesting that enhanced microcirculation via vasodilators and anti-thrombolytics might be an effective approach at optimizing the delivery of oxygen to hepatocytes |
| Minor et al. (38) | Porcine COR vs. HMP vs. SNMP vs. SCS | ECD; N = 6/group CIT: 18 h |
1.5 h | COR significantly reduced cellular enzyme loss, gene expression and perfusate activities of TNF-α, radical mediated lipid peroxidation, and increase of portal vascular perfusion resistance upon reperfusion, while HMP or SNMP were less protective |
| Schlegel et al. (28) | Rats HOPE vs. deoxygenated MP with heterogenic Tx ± immunosuppression | CIT: 30 min | 1 h | Study demonstrated that allograft treatment by HOPE not only protects against preservation injury but also impressively downregulates the immune system, blunting the alloimmune response |
| Bae et al. (33) | Rats HMP with KPS-1 vs. VAS ± VitE vs. SCS without Tx |
DCD; N = 5/group WIT: 30 min |
8 h | VAS perfusion solution was superior compared with KPS-1, and supplementation of VAS with VitE reduced not only the level of ALT but also levels of inflammatory cytokines (IL-6, TNF-α, and MCP-1) in graft tissue and caspase 3/7 in the circulation |
| Knaak et al. (39) | Porcine SNMP without Tx | DCD; N = 5 WIT: 45 min CIT: 4 h |
6 h | SNMP minimized cold ischemic injury and allowed to assess ECD liver grafts prior to Tx |
| Nassar et al. (66) | Porcine NMP ± vasodilators (prostacyclin or adenosine) without Tx |
DCD; N = 5/group WIT: 60 min |
10 h | Livers perfused with the addition of prostacyclin showed a significantly higher outcome over those perfused by adding adenosine or without vasodilators, indicating the necessity of potent, efficient vasodilation in order to achieve effective preservation of DCD livers during NMP |
| Nassar et al. (67) | Porcine NMP vs. SNMP vs. SCS followed by 24 h machine reperfusion | DCD; N = 5/group WIT: 60 min |
10 h | NMP was able to recover DCD livers showing superior hepatocellular integrity, biliary function, and microcirculation compared to SNMP and SCS |
| Ferrigno et al. (68) | Rats SNMP vs. SCS ± oxygenated washout Rats SNMP vs. SCS Both followed by 2 h machine reperfusion |
DCD; N = 7/group WIT: 30 min Steatotic livers; N = 7/group |
6 h | The use of oxygenated washout before SCS reversed liver injury in DCD organs, improving the ATP/ADP ratio; the use of MP did not otherwise prevent liver damage Using dynamic MP, a significantly lower hepatic damage and an increase in bile flow and in the ATP/ADP ratio were found compared with those of the SCS group |
| Chai et al. (69) | Rats HMP with UW ± metformin (0.165 mg/L) without Tx | Young and aged livers; N = 6/group | 12 h | The addition of metformin to the UW preservation solution for ex vivo HMP reduced liver injury during cold ischemia, with significant protective effects on livers, especially of aged rats |
| Kron et al. (70) | Rats HOPE vs. SCS with Tx | Steatotic livers (≥60% macrosteatosis); N = 12/group CIT: 12 h |
1 h | HOPE after cold storage of severely fatty livers significantly prevented reperfusion injury (less oxidative stress, nuclear injury, Kupffer and endothelial cell activation, as well as less fibrosis within 1 week after Tx) and improved graft function |
| Compagnon et al. (71) | Porcine HMP vs. SCS with Tx | DCD; N = 6/group WIT: 1 h |
4 h | HMP-preserved livers functioned better and showed less hepatocellular and endothelial cell injury. In addition to improved energy metabolism, this protective effect was associated with an attenuation of inflammatory response, oxidative load, endoplasmic reticulum stress, mitochondrial damage, and apoptosis |
| Kakizaki et al. (72) | Porcine SNMP vs. SCS with Tx | DCD vs. DBD; N = 5/group WIT: 20 min CIT: 4 h |
30 min | SNMP before Tx provided some recovery from IR injury in DCD liver grafts and significantly improved the survival rate |
| Nostedt et al. (73) | Porcine NMP after initial flush with different solutions and temperatures without Tx | DCD; N = 4/group WIT: 1 h |
12 h | Avoiding initial hypothermia does not improve liver graft quality in a porcine DCD model of NMP |
| HUMAN STUDIES | ||||
| Henry et al. (34) | HMP vs. SCS with Tx |
N = 18 vs. 15 WIT: 45.1 ± 6.3 min CIT: 9.3 ± 2.2 h |
4.2 ± 0.9 h | HMP significantly reduced pro-inflammatory cytokine expression, relieving the downstream activation of adhesion molecules (ICAM-1) and migration of leukocytes, including neutrophils and macrophages, leading to improved overall outcomes |
| Bruinsma et al. (74) | SNMP without Tx | High-risk DCD and DBD; N = 7 WIT: ~28 min CIT: ~11.5 h |
3 h | SNMP effectively maintained liver function with minimal injury and sustained or improved various hepatobiliary parameters post-ischemia |
| Dutkowski et al. (75) | HOPE vs. SCS with Tx | DCD; N = 50 vs. 25 WIT: ~35 min CIT: ~6.5 h |
~2 h | HOPE protected extended DCD livers from initial reperfusion injury, leading to a better graft function and the prevention of intrahepatic biliary complications. Acute rejection rate was similar (16 vs. 12%) |
| Vogel et al. (76) | NMP without Tx | DCD (69%); N = 13 Mean age: 61.9 ± 11.3 years WIT: 11.3 ± 4 min CIT: 9.5 ± 3.7 h |
24 h | They demonstrated the possibility to perfuse high-risk livers consistently for 24 h. The neutrophil infiltrate in grafts was eliminated after prolonged NMP |
| Laing et al. (77) | NMP with Hemopure* vs. RBC- based solution (matched) without Tx |
High-risk (80% DCD); N = 5/group CIT: 7.5 h |
6 h | Hemopure-based perfusion fluid is a feasible alternative to the blood-based solution currently used for liver NMP and may be logistically, rheologically, and immunologically superior to packed RBCs |
| Nasralla et al. (78) | NMP vs. SCS with Tx | DBD and DCD (~36%); N = 121 vs. 101 | ~9 h | NMP was associated with a 50% lower level of graft injury, measured by hepatocellular enzyme release, despite a 50% lower rate of organ discard and a 54% longer mean preservation time. There was no significant difference in bile duct complications, graft survival, or survival of the patient |
ALT, alanine aminotransaminase; CIT, cold ischemia time; COR, controlled oxygenated rewarming; ECD, extended criteria donor; DCD, donation after circulatory death; HLA, human leukocyte antigen; HMP, hypothermic MP; HOPE, hypothermic oxygenated perfusion; ICAM, intercellular adhesion molecule; IL, interleukin; IRI, ischemia–reperfusion injury; LDH, lactate dehydrogenase; MCP, monocyte chemoattractant protein; MP, machine perfusion; NMP, normothermic MP; RBC, red blood cell; SCS, static cold storage; SNMP, subnormothermic MP; TNF, tumor necrosis factor; Tx, transplantation; WIT, warm ischemia time; HTK, histidine-tryptophan-ketoglutarate solution; VAS, vasosol solution; DBD, donor after brain death.