Liver machine perfusion technology: Expanding the donor pool to improve access to liver transplantation.

The imbalance between organ supply and demand continues to limit the broader benefits of organ transplantation. Machine perfusion (MP) may increase the supply of donor livers by expanding the use of extended-criteria donors. Using the United Network for Organ Sharing/Organ Procurement and Transplantation Network and the Standard Transplant Analysis and Research dataset, we reviewed the effect of MP implementation on the behavior of transplant centers. We identified 15 high-utilizing MP centers that were matched to suitable controls based on volume and geographical proximity. We conducted a differences-in-differences analysis using linear regression to estimate the impact of MP adoption on the transplant centers' donor utilization. We found a significant increase in cold ischemia time and organs with donor warm ischemia time over 30 minutes (P < .05). After removing one outlier center, the analysis showed that these centers through MP accepted overall more donation after circulatory death donors, donation after circulatory death donors over 50 years old, donors with macrovesicular steatosis greater than 30% on liver biopsy, and donor warm ischemia time over 30 minutes (P < .05). MP has allowed centers to expand their use of extended-criteria donors beyond traditional cutoffs and to increase patient access to liver transplantation.

Liver Transplantation 2023: Status Report, Current and Future Challenges.

Liver transplantation offers live-saving therapy for patients with complications of cirrhosis and stage T2 hepatocellular carcinoma. The demand for organs far outstrips the supply, and innovations aimed at increasing the number of usable deceased donors as well as alternative donor sources are a major focus. The etiologies of cirrhosis are shifting over time, with more need for transplantation among patients with alcohol-associated liver disease and nonalcoholic/metabolic fatty liver disease and less for viral hepatitis, although hepatitis B remains an important indication for transplant in countries with high endemicity. The rise in transplantation for alcohol-associated liver disease and nonalcoholic/metabolic fatty liver disease has brought attention to how patients are selected for transplantation and the strategies needed to prevent recurrent disease. In this review, we present a status report on the most pressing topics in liver transplantation and future challenges.

Lungs From Donors ≥70 Years of Age for Transplantation-Do Long-Term Outcomes Justify Their Use?

Donor shortages have led transplant centers to extend their criteria for lung donors. Accepting lung donors ≥70 years of age has previously shown good short-term outcomes; however, no mid- and long-term outcome data on these extended criteria donors has been published to date. In this study, all patients who underwent lung transplantation between 06/2010 and 12/2019 were included in the analysis, and the outcomes were compared between patients receiving organs from donors <70 years of age and patients transplanted with lungs from donors ≥70 years of age. Among the 1,168 lung-transplanted patients, 62 patients received lungs from donors ≥70 years of age. The recipient age of those receiving older organs was significantly higher, and they were more likely to suffer from obstructive lung disease. Older donors were exposed to significantly shorter periods of mechanical ventilation prior to donation, had higher Horowitz indices, and were less likely to have smoked. The postoperative time on mechanical ventilation, time on ICU, and total hospital stay were comparable. The overall survival as well as CLAD-free survival showed no differences between both groups in the follow-up period. Utilization of lungs from donors ≥70 years of age leads to excellent mid- and long-term results that are similar to organs from younger donors when the organs from older donors are carefully preselected.

Interleukin-18 and High-Mobility-Group-Protein B1 are Early and Sensitive Indicators for Cell Damage During Normothermic Machine Perfusion after Prolonged Cold Ischemic Storage of Porcine Liver Grafts.

In the era of organ machine perfusion, experimental models to optimize reconditioning of (marginal) liver grafts are needed. Although the relevance of cytokine signatures in liver transplantation has been analyzed previously, the significance of molecular monitoring during normothermic machine perfusion (NMP) remains elusive. Therefore, we developed a porcine model of cold ischemic liver graft injury after prolonged static cold storage (SCS) and subsequent NMP: Livers obtained from ten minipigs underwent NMP for 6 h directly after procurement (control group) or after 20 h of SCS. Grafts after prolonged SCS showed significantly elevated AST, ALT, GLDH and GGT perfusate concentrations, and reduced lactate clearance. Bile analyses revealed reduced bile production, reduced bicarbonate and elevated glucose concentrations after prolonged SCS. Cytokine analyses of graft perfusate simultaneously demonstrated an increase of pro-inflammatory cytokines such as Interleukin-1α, Interleukin-2, and particularly Interleukin-18. The latter was the only significantly elevated cytokine compared to controls, peaking as early as 2 h after reperfusion (11,012 ng/ml vs. 1,493 ng/ml; p = 0.029). Also, concentrations of High-Mobility-Group-Protein B1 were significantly elevated after 2 h of reperfusion (706.00 ng/ml vs. 148.20 ng/ml; p < 0.001) and showed positive correlations with AST (r 2 = 0.846) and GLDH (r 2 = 0.918) levels. Molecular analyses during reconditioning of liver grafts provide insights into the degree of inflammation and cell damage and could thereby facilitate future interventions during NMP reducing acute and chronic graft injury.

Utilization of hepatitis B virus surface antigen positive grafts in liver transplantation: A matched study based on a national registry cohort.

BACKGROUND AND AIM: Donor shortage has become worldwide limitation in liver transplantation (LT). Use of hepatitis B virus surface antigen positive (HBsAg+) donors could be an alternative source of donor organs. This study aims to investigate the safety and efficacy of LT using HBsAg+ liver grafts and associated long-term outcome. METHODS: This was a retrospective study of adults LT registered in the database of the China Liver Transplant Registry between January 2015 and September 2018. By propensity score matching (1:1), 503 eligible patients who received HBsAg+ liver grafts were compared with 503 matched patients who received HBsAg- liver grafts. RESULTS: The 1-, 3-, and 5-year patient survival rates were 81.52%, 72.04%, and 66.65% in HBsAg+ donor group, which were comparable with 83.93%, 77.27%, and 65.73% in HBsAg- donor group (P = 0.222). The 1-, 3-, and 5-year graft survival rates were also comparable between the two groups (81.49%, 71.45%, and 67.26% vs 83.62%, 77.11%, and 65.81%, respectively, P = 0.243). Most main complications were not increased in HBsAg+ donor group except for the retaining of HBsAg positivity after LT. Furthermore, transplanting HBsAg+ liver grafts did not result in inferior outcomes either in HBsAg+ or HBsAg- recipients. The risk of tumor recurrence after LT was not increased in hepatocellular carcinoma patients. CONCLUSIONS: The outcomes of using HBsAg+ liver grafts were comparable with those of HBsAg- liver grafts. Our study provided strong evidence for the safe use of HBsAg+ grafts in LT to expand the donor liver pool.

Hypothermic oxygenated machine perfusion for extended criteria donor allografts: Preliminary experience with extended organ preservation times in the setting of organ reallocation.

BACKGROUND: In times of critical organ shortage, poor organ pool utilization and increased use of extended-criteria donor (ECD) allografts remain a major problem. Hypothermic oxygenated machine perfusion (HOPE) has emerged as a promising and feasible strategy in ECD liver transplantation (LT). However, potential safety limits regarding the duration of perfusion are yet to be explored. Besides marginal allograft quality (steatosis), prolonged cold ischemia time remains the most important factor for a high number of liver allografts being declined for transplantation. PATIENTS AND METHODS: Two ECD-allografts were each allocated to two recipients, who proved to be unsuitable to receive the assigned allograft upon arrival at the transplant center. The organs were reallocated by Eurotransplant and accepted by our center for two different backup patients. During that time, HOPE was commenced and continued until the recipient hepatectomy was completed. Postoperative allograft function was assessed by serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), bilirubin, and International Normalized Ratio. Incidence of early allograft dysfunction (EAD), postoperative complications, and length of hospital stay were analyzed. RESULTS: HOPE was applied for 4 h 35 min and 4 h 20 min, resulting in a total cold preservation time of 17 h 29 min and 15 h 20 min, respectively. Both recipients displayed decreasing serum transaminases and bilirubin levels postoperatively. No EAD or major postoperative complications occurred in either patient. Serum ALT and AST levels were within the normal range at discharge. CONCLUSIONS: Extended HOPE enables the safe extension of preservation time for up to 18 h in human LT. End-ischemic HOPE may significantly improve organ pool utilization, while simultaneously facilitating operating room logistics and preventing organ injury.

Aggressive pursuit and utilization of non-ideal donor lungs does not compromise post-lung transplant survival.

BACKGROUND: Organ procurement organizations (OPOs) vary in willingness to pursue and utilize non-ideal donor lungs; implications of these practices for lung transplant (LTx) recipients remain unclear. We examined associations between OPO-level behavior toward non-ideal donors and post-LTx outcomes. METHODS: Adult lung donors and corresponding adult first-time LTx recipients in the 2008-2019 UNOS registry were included. Non-ideal donors had any of age > 50, smoking history ≥20 pack-years, PaO2 /FiO2 ratio ≤350, donation after circulatory death, or increased risk status. OPOs were classified as least, moderately, or most aggressive based on non-ideal donor pursuit, consent attainment, lung recovery, and transplantation. Post-transplant outcomes were compared among aggressiveness strata. RESULTS: Of 22,795 recipients, 6229 (27.3%), 8256 (36.2%), and 8310 (36.5%) received lungs from least, moderately, and most aggressive OPOs, respectively. Moderately aggressive OPOs had the highest recipient rates of pre-discharge acute rejection, grade 3 primary graft dysfunction, postoperative extracorporeal membrane oxygenation, and longest lengths of stay. After adjustment, moderately and most aggressive OPOs had similar risks of recipient mortality as least aggressive OPOs. CONCLUSIONS: The most and least aggressive OPOs achieve similar patient survival and short-term post-LTx outcomes. Aggressive pursuit and utilization of non-ideal donor lungs by less aggressive OPOs would likely expand the donor pool, without compromising recipient outcomes.

Early- and long-term outcomes of liver transplantation with rescue allocation grafts.

In France, liver grafts which have been refused by at least five centers are proposed as rescue allocation (RA). The aim of this study is to clarify the feasibility and safety of RA grafts in liver transplantation (LT). Short- and long-term outcomes of patients who received RA grafts (RA group) were compared with those of patients who received standard allocation (SA) grafts (SA group). From a total of 1635 patients, 102 patients received RA grafts. Before matching, the RA group was characterized primarily by less severe liver disease, but the quality of graft was worse. After matching recipients' characteristics of 102 patients who used RA grafts with 306 patients who used SA grafts, recipients' characteristics were well balanced (1:3 matching). Although the rate of primary dysfunction was significantly higher in the RA group, there is no significant difference in the occurrence of major complications, length of hospitalization, and mortality between two groups. Graft survival (GS) and overall survival (OS) in the RA group were not significantly different from the SA group (GS; HR = 1.03 P = .89, OS; HR = 1.03 P = .90). In the French allocation system, the feasibility and safety of RA grafts might be comparable to SA grafts for carefully selected patients.

Graft utilization after normothermic regional perfusion in controlled donation after circulatory death-a single-center perspective from France.

Normothermic regional perfusion (NRP) in controlled donation after circulatory death (cDCD) is a promising procurement strategy. However, a detailed analysis of graft utilization rates is lacking. This retrospective study included all cDCD donors proposed to a single center for NRP procurement of at least one abdominal organ from 2015 to 2020. Utilization rates were defined as the proportion of transplanted grafts from proposed donors in which withdrawal of life sustaining therapies (WLST) was initiated. In total, 125 cDCD donors underwent WLST with transplantation of at least one graft from 109 (87%) donors. In a total of 14 (11%) procedures NRP failure led to graft discard. Utilization rates for kidney and liver grafts were 83% and 59%, respectively. In 44% of the discarded livers, the reason was poor graft quality based on functional donor warm ischemia >45 min, macroscopic aspect, high-transaminases release, or pathological biopsy. In this study, abdominal NRP in cDCD lead to transplantation of at least one graft in the majority of cases. While the utilization rate for kidneys was high, nearly half of the liver grafts were discarded. Cannulation training, novel graft viability markers, and ex-vivo liver graft perfusion may allow to increase graft utilization.

Impact of center donor acceptance patterns on utilization of extended-criteria donors and outcomes.

BACKGROUND: This study investigated the impact of transplanting center donor acceptance patterns on usage of extended-criteria donors (ECDs) and posttransplant outcomes following orthotopic heart transplantation (OHT). METHODS: The Scientific Registry of Transplant Recipients was queried to identify heart donor offers and adult, isolated OHT recipients in the United States from January 1, 2013 to October 17, 2018. Centers were stratified into three equal-size terciles based on donor heart acceptance rates (<13.7%, 13.7%-20.2%, >20.2%). Overall survival was compared between recipients of ECDs (≥40 years, left ventricular ejection fraction [LVEF] <60%, distance ≥500 miles, hepatitis B virus [HBV], hepatitis C virus [HCV], or human immunodeficiency virus [HIV], or ≥50 refusals) and recipients of traditional-criteria donors, and among transplanting terciles. RESULTS: A total of 85,505 donor heart offers were made to 133 centers with 15,264 (17.9%) accepted for OHT. High-acceptance programs (>20.2%) more frequently accepted donors with LVEF <60%, HIV, HCV, and/or HBV, ≥50 offers, or distance >500 miles from the transplanting center (each p < .001). Posttransplant survival was comparable across all three terciles (p = .11). One- and five-year survival were also similar across terciles when examining recipients of all five ECD factors. Acceptance tier and increasing acceptance rate were not found to have any impact on mortality in multivariable modeling. Of ECD factors, only age ≥40 years was found to have increased hazards for mortality (hazard ratio, 1.33; 95% confidence interval [CI], 1.22-1.46; p < .001). CONCLUSIONS: Of recipients of ECD hearts, outcomes are similar across center-acceptance terciles. Educating less aggressive programs to increase donor acceptance and ECD utilization may yield higher national rates of OHT without major impact on outcomes.

Prolonged extracorporeal preservation and evaluation of human lungs with portable normothermic ex vivo perfusion.

Many lung donor offers are refused despite increasing demand. Portable normothermic ex vivo lung perfusion (EVLP) could increase donor yield by monitoring and reconditioning extended criteria donor (ECD) lungs. We report its use in human lungs declined for clinical transplantation. Ten sets of such lungs were procured from brain-dead donors and underwent 24 hours of normothermic EVLP using a perfusate based on donor whole blood. Hemodynamic and ventilatory data and P:F ratios were measured. Advanced donor age and borderline oxygenation (donor mean P:F 228 ± 73) were the most commonly cited reasons for refusal for transplantation. There was no significant worsening of pulmonary hemodynamics or compliance or significant P:F decline during preservation in the overall cohort. Mean P:F ratio in the overall cohort was 315 ± 88 mm Hg after 24 hours EVLP. At EVLP termination 5/10 lung blocks met standard EVLP thresholds for acceptability for transplant. Eventual EVLP performance was poorly predicted by donor P:F ratio but well predicted by data gathered early in EVLP. Portable normothermic EVLP is useful for transportation, monitoring, and reconditioning of ECD lungs. Early EVLP measurements are more effective than preprocurement donor P:F in predicting eventual allograft performance. We advocate an aggressive strategy of evaluation of ECD lungs using blood-based EVLP.

Are the outcomes of Japanese pancreas transplantation utilizing extended-criteria donors acceptable? A propensity score matching analysis for donors <50 or ≥50 years old.

In Japan, about 30% of pancreatic transplant donors are ≥50 years old, making them "extended-criteria donors (ECDs)." We analyzed 361 cases of transplantation involving donors from the Japanese pancreas transplantation registry to evaluate the acceptability of ECDs. The patient survival rates at 1, 5, and 10 years after transplantation were 96.6%, 94.9%, and 88.3%, respectively. The survival rates of pancreas and kidney grafts at 1, 5, and 10 years were 85.3%, 74.8%, and 70.6%, and 94.2%, 90.9%, and 80.9%, respectively. Multivariate analysis revealed that no particular donor factors significantly influenced the pancreatic graft survival. Patients were divided into 2 groups: donors ≥50 years old (older group) and those <50 years old (younger group). After propensity score matching, the overall pancreatic graft survival at 1, 5, and 10 years after transplantation in the older group was 82.8%, 71.8%, and 69.5%, respectively, which was almost the same as in the younger group (84.9%, 70.2%, and 67.4%, respectively). No donor factors markedly influenced the pancreatic graft survival, and the outcomes of pancreas transplantation from ECDs ≥50 years old were comparable to those from younger donors.

Impact of donor preprocurement cardiac arrest on clinical outcomes in pediatric deceased donor liver transplantation.

PPCA has historically been considered detrimental to donor quality in LT, but transplantation of grafts from this group of donors is now routine. Our study aims to evaluate the outcomes associated with use of donors with a history of PPCA in the pediatric population. This study is a single-center retrospective analysis of all pediatric LTs performed over an 18-year period. Donors and recipients were stratified by the presence and length of donor PPCA time. Preprocurement donor and post-transplant recipient laboratory values were collected to assess the degree of ischemic liver injury associated with each donor group. Cox regression analysis was used to compare survival. The records for 130 deceased pediatric LT donors and corresponding recipients were reviewed. There were 73 (56%) non-PPCA donors and 57 (44%) PPCA donors. Donors that experienced a PPCA event demonstrated a higher median, pretransplant peak alanine aminotransferase (ALT) level (P < .001). When comparing post-transplant recipient median ALT levels, donors with any PPCA had lower median peak ALT (P = .15) and day 3 ALT (P = .43) levels than the non-PPCA group. Rates of early graft loss did not differ. The PPCA group with >40 minutes of ischemia had markedly lower survival at 10 years, but this finding did not reach statistical significance. Liver grafts from donors with or without PPCA demonstrated no statistically significant differences in function or survival. A history of donor PPCA alone should not be used as an exclusionary criterion in pediatric liver transplantation.

Update on liver transplantation-newer aspects

Liver transplantation (LT) remains the only therapeutic option offering gold standard treatment for end-stage liver disease (ESLD) and acute liver failure (ALF), as well as for certain early-stage liver tumors. Currently, the greatest challenge facing LT is the simple fact that there are not enough adequate livers for all the potential patients that could benefit from LT. Despite efforts to expand the donor pool to include living and deceased donors, organ shortage is still a major problem in many countries. To solve this problem, the use of marginal liver grafts has become an inevitable choice. Although the definition of marginal grafts or criteria for expanded donor selection has not been clarified yet, they are usually defined as grafts that may potentially cause primary nonfunction, impaired function, or late loss of function. These include steatotic livers, older donors, donors with positive viral serology, split livers, and donation after cardiac death (DCD). Therefore, to get the best outcome from these liver grafts, donor-recipient selection should be vigilant. Alcohol- related liver disease (ALD) is one of the most common indications for LT in Europe and North America. Traditionally, LT for alcoholic liver disease was kept limited for patients who have achieved 6 months of abstinence, in part due to social and ethical concerns regarding the use of a limited resource. However, the majority of patients with severe alcoholic hepatitis who fail medical therapy will not live long enough to meet this requirement. Besides, the initial results of early liver transplantation (ELT) without waiting for 6 months of abstinence period are satisfactory in severe alcoholic hepatitis (SAH). It will be important to take care of these patients from a newer perspective.

Machine Perfusion and the Pancreas: Will It Increase the Donor Pool?

PURPOSE OF REVIEW: Pancreas transplantation enables complete patient independence from exogenous insulin administration and increases both patient survival and quality of life. Despite this, there has been a decline in pancreas transplantation for the past 20 years, influenced by changing donor demographics with more high-risk extended criteria (ECD) and donation after cardiac death (DCD) donors. This review discusses whether the advent of machine perfusion (MP), if extended to the pancreas, can increase the pool of suitable donor organs. RECENT FINDINGS: Hypothermic and normothermic MP, as forms of preservation deemed superior to cold storage for high-risk kidney and liver donor organs, have opened the avenue for translation of this work into the pancreas. Recent experimental models of porcine and human ex-vivo pancreatic MP are promising. Applications of MP to the pancreas however need refinement-focusing on perfusion protocols and viability assessment tools. Emerging research shows pancreatic MP can potentially offer superior preservation capacity, the ability to both resuscitate and manipulate organs, and assess functional and metabolic organ viability. The future of MP will lie in organ assessment and resuscitation after retrieval, where ultimately organs initially considered high risk and unsuitable for transplantation will be optimised and transformed, making them then available for clinical use, thus increasing the pool of suitably viable pancreata for transplantation.

Transplantation of donor lungs with pulmonary embolism - a retrospective study.

Lung transplantation from donors with fulminant pulmonary arterial embolism as a cause of death remains controversial. An analysis was performed comparing preoperative characteristics and outcomes of 25 donors with a primary diagnosis of pulmonary arterial embolism to 1085 recipients of donor lungs without pulmonary arterial embolism. No early functional impairment of donor lungs with pulmonary embolism was detectable as depicted by the incidence of primary graft dysfunction immediately after surgery (P = 0.66), 24 (P = 0.79), 48 (P = 0.99) and 72 h (P = 0.99) after transplantation. Pulmonary function testing at 1 year (P = 0.003) and at last outpatient control (P < 0.05) showed superior results in the cohort receiving lungs from donors with pulmonary embolism. Incidence of chronic lung allograft dysfunction (CLAD) showed no difference within the first year after lung transplantation, however, 5 year-CLAD free survival was superior in recipients (70.4% vs. 55.1%, P = 0.006) of donor lungs with pulmonary embolism. Overall survival was similar in both groups. Lungs from donors with fulminant pulmonary embolism prior to brain death can safely be used for lung transplantation without impairing postoperative outcomes. Lung function testing shows favorable midterm results in recipients of donor lungs with pulmonary embolism.

Feasibility of lung transplantation from donors mechanically ventilated for prolonged periods.

PURPOSE: When patients are mechanically ventilated for more than 5 days, they are usually declined as donors for lung transplantation (LTx); thus, the long-term outcomes of LTx from such donors remain unclear. We investigated the feasibility of LTx from donors that had been mechanically ventilated for prolonged periods. METHODS: The subjects of this retrospective comparative investigation were 31 recipients of LTx from donors who had been mechanically ventilated for < 5 days (short-term group) and 50 recipients of LTx from donors who had been mechanically ventilated for ≥ 5 days (long-term group). RESULTS: The median duration of donor mechanical ventilation was 3 days in the short-term group and 8.5 days in the long-term group. However, other than the difference in the duration of donor ventilation, there were no significant differences in the clinical characteristics of the donors or recipients between the groups. The overall survival rate after LTx was comparable between the long-term group and short-term group (5-year survival rate, 66.6% vs. 75.2%). CONCLUSION: The potential inclusion of donors who have been on mechanical ventilation for more than 5 days could be a feasible strategy to alleviate donor organ shortage.

Safety of dual kidney transplantation compared to single kidney transplantation from expanded criteria donors: a single center cohort study of 39 recipients.

Our objective was to compare the outcomes of dual kidney transplanataion (DKT) to single kidney transplantation (SKT) performed with grafts from expanded criteria donors (ECD) in recipients ≥65 years, focusing on surgical complications. All kidney transplantations (KT) performed between 2006 and 2014 in our institution were analysed. DKT was indicated according to the criteria of the French national Agence de la Biomedecine. Thirty-nine DKT and 155 SKT were included, with a median follow-up of 36 and 26.5 months, respectively. The rate of early surgical revisions was not significantly higher after DKT (23.1% vs 15.5% (P = 0.2593)) but more venous graft thromboses (12.8% vs 3.2% (P = 0.02)) were reported. The glomerular filtration rate (GFR) 24 months after KT was significantly higher after DKT (45.0 ± 16.3 vs 39.8 ± 13.8 ml/min/1.73m2 ; P = 0.04) and allowed shorter waiting time without a significant increased risk of surgical revision, excepted for venous graft thrombosis, more frequent after DKT. Graft survivals were not significantly different and GFR was higher after DKT. DKT seems to remain an appropriate strategy to address the growing graft shortage in elderly patients.

A severely cholestatic liver graft can be successfully used in deceased donor liver transplantation.

The shortage of deceased organs is still a serious issue in Japan. A proactive approach to using liver grafts from extended criteria donors (ECDs) may be one way of expanding the donor pool; however, if it is recklessly attempted, a recipient receiving such a marginal graft can be at risk of mortality due to primary non-function or delayed graft function. We herein report the successful outcome of a recipient receiving a severely cholestatic graft that was considered transplantable because it lacked features characteristic of a long duration of "cholestasis" according to the precise interpretation of a donor biopsy. Plasma exchange was intentionally introduced to prevent toxic insult by hyperbilirubinemia immediately after transplant. Despite transient acute kidney injury immediately after transplant, the patient's renal impairment was well managed with a renal-sparing immunosuppressive regimen consisting of basiliximab and mycophenolate mofetil. Although the use of liver grafts from ECDs still needs to be discussed, especially regarding graft selection and allocation policies, efforts not to discard valuable grafts should be undertaken in our country.

Complement Activation in Liver Transplantation: Role of Donor Macrosteatosis and Implications in Delayed Graft Function.

The complement system anchors the innate inflammatory response by triggering both cell-mediated and antibody-mediated immune responses against pathogens. The complement system also plays a critical role in sterile tissue injury by responding to damage-associated molecular patterns. The degree and duration of complement activation may be a critical variable controlling the balance between regenerative and destructive inflammation following sterile injury. Recent studies in kidney transplantation suggest that aberrant complement activation may play a significant role in delayed graft function following transplantation, confirming results obtained from rodent models of renal ischemia/reperfusion (I/R) injury. Deactivating the complement cascade through targeting anaphylatoxins (C3a/C5a) might be an effective clinical strategy to dampen reperfusion injury and reduce delayed graft function in liver transplantation. Targeting the complement cascade may be critical in donor livers with mild to moderate steatosis, where elevated lipid burden amplifies stress responses and increases hepatocyte turnover. Steatosis-driven complement activation in the donor liver may also have implications in rejection and thrombolytic complications following transplantation. This review focuses on the roles of complement activation in liver I/R injury, strategies to target complement activation in liver I/R, and potential opportunities to translate these strategies to transplanting donor livers with mild to moderate steatosis.