Reduction of reperfusion injury with prostacyclin I2 after liver transplantation

Prostaglandins for adult liver transplanted recipients

BACKGROUND

Prostaglandins are naturally occurring lipids that are synthesised from arachidonic acid. Multiple studies have evaluated the benefits of prostaglandins in reducing ischaemia reperfusion injury after liver transplantation. New studies have been published since the previous review, and hence it was important to update the evidence for this intervention.

OBJECTIVES

To evaluate the benefits and harms of prostaglandins in adults undergoing liver transplantation compared with placebo or standard care.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was 27 December 2022.

SELECTION CRITERIA

We included randomised clinical trials evaluating prostaglandins initiated in the perioperative period compared with placebo or standard care for adults undergoing liver transplantation. We included trials irrespective of reported outcomes.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our primary outcomes were 1. all-cause mortality, 2. serious adverse events, and 3. health-related quality of life. Our secondary outcomes were 4. liver retransplantation, 5. early allograft dysfunction, 6. primary non-function of the allograft, 7. acute kidney failure, 8. length of hospital stay, and 9. adverse events considered non-serious. We used GRADE to assess certainty of evidence.

MAIN RESULTS

We included 11 randomised clinical trials with 771 adult liver transplant recipients (mean age 47.31 years, male 61.48%), of whom 378 people were randomised to receive prostaglandins and 393 people were randomised to either placebo (272 participants) or standard care (121 participants). All trials were published between 1993 and 2016. Ten trials were conducted in high- and upper-middle-income countries. Prostaglandins may reduce all-cause mortality up to one month (risk ratio (RR) 0.86, 95% confidence interval (CI) 0.61 to 1.23; risk difference (RD) 21 fewer per 1000, 95% CI 63 fewer to 36 more; 11 trials, 771 participants; low-certainty evidence). Prostaglandins may result in little to no difference in serious adverse events (RR 0.92, 95% CI 0.60 to 1.40; RD 81 fewer per 1000, 95% CI 148 fewer to 18 more; 6 trials, 568 participants; low-certainty evidence). None of the included trials reported health-related quality of life. Prostaglandins may result in little to no difference in liver retransplantation (RR 0.98, 95% CI 0.49 to 1.96; RD 1 fewer per 1000, 95% CI 33 fewer to 62 more; 6 trials, 468 participants; low-certainty evidence); early allograft dysfunction (RR 0.62, 95% CI 0.33 to 1.18; RD 137 fewer per 1000, 95% CI 241 fewer to 47 more; 1 trial, 99 participants; low-certainty evidence); primary non-function of the allograft (RR 0.58, 95% CI 0.26 to 1.32; RD 23 fewer per 1000, 95% CI 40 fewer to 16 more; 7 trials, 624 participants; low-certainty evidence); and length of hospital stay (mean difference (MD) -1.15 days, 95% CI -5.44 to 3.14; 4 trials, 369 participants; low-certainty evidence). Prostaglandins may result in a large reduction in the development of acute kidney failure requiring dialysis (RR 0.42, 95% CI 0.24 to 0.73; RD 100 fewer per 1000, 95% CI 132 fewer to 49 fewer; 5 trials, 477 participants; low-certainty evidence). The evidence is very uncertain about the effect of prostaglandins on adverse events considered non-serious (RR 1.19, 95% CI 0.42 to 3.36; RD 225 fewer per 1000, 95% CI 294 fewer to 65 fewer; 4 trials, 329 participants; very low-certainty evidence). Two trials reported receiving funding; one of these was with vested interests. We found one registered ongoing trial.

AUTHORS' CONCLUSIONS

Eleven trials evaluated prostaglandins in adult liver transplanted recipients. Based on low-certainty evidence, prostaglandins may reduce all-cause mortality up to one month; may cause little to no difference in serious adverse events, liver retransplantation, early allograft dysfunction, primary non-function of the allograft, and length of hospital stay; and may have a large reduction in the development of acute kidney injury requiring dialysis. We do not know the effect of prostaglandins on adverse events considered non-serious. We lack adequately powered, high-quality trials evaluating the effects of prostaglandins for people undergoing liver transplantation.

An evaluation of the safety and preliminary efficacy of peri- and post-operative treprostinil in preventing ischemia and reperfusion injury in adult orthotopic liver transplant recipients

Background

Orthotopic liver transplantation (OLT) is the only treatment option for various end‐stage liver diseases. Ischemia and reperfusion (I/R) injury is one of the unavoidable complications/conditions in OLT. In 2019, a total of 8896 livers were transplanted of which >94% organs were procured from deceased donors. An increase in the use of extended criteria donor (ECD) livers for transplantation further unraveled the role of hepatic I/R injury on short‐term and long‐term graft outcomes. Despite promising outcomes with the use of antioxidants, free radical scavengers, and vasodilators; I/R‐mediated liver injury persists and significantly influences the overall clinical outcomes. Treprostinil, a synthetic prostacyclin I₂ (PGI₂) analog, due to its vasodilatory property, antiplatelet activity, and its ability to downregulate pro‐inflammatory cytokines can potentially minimize I/R injury.

Aim

We investigated the safety and preliminary efficacy of continuous intravenous infusion of treprostinil in liver transplant recipients in a prospective, single‐center, non‐randomized, interventional study.

Material and methods

This was a dose escalation (3 + 3 design) phase 1/2 study. Deceased donor liver transplant recipients received 5 ng/kg/min for two days, or 2.5, 5, and 7.5 ng/min/kg for 5 days as a continuous infusion. Multiple blood samples were collected for biochemical parameter assessment and for measuring treprostinil levels. Indocyanine green plasma disappearance rate was used as a measure of hepatic functional capacity.

Results

Subjects tolerated continuous infusion of treprostinil up to 5 ng/kg/min for 120 h with no occurrence of primary graft non‐function (PNF), minimized need for ventilation support, reduced hospitalization time, 100% graft and patient survival, and improved hepatobiliary excretory function comparable to normal healthy adults.

Discussion

Treprostinil can be administered to liver transplant patients safely during the perioperative period.

Conclusion

Based on this phase 1/2 study, further efficacy studies of treprostinil in preventing I/R injury of liver should be conducted to potentially increase the number of livers available for transplantation.

Early Measurement of Indocyanine Green Clearance Accurately Predicts Short-Term Outcomes After Liver Transplantation

BACKGROUND

There are no accurate tools to predict short-term mortality or the need for early retransplantation after liver transplantation (LT). A noninvasive measurement of indocyanine green clearance, the plasma disappearance rate (PDR), has been associated with initial graft function.

METHODS

We evaluated the ability of PDR to predict early mortality or retransplantation after LT. In this observational prospective study, 332 LT were analyzed. Donor, recipient, and intraoperative data were investigated. The ensuing score was prospectively evaluated in a validation cohort of 77 patients.

RESULTS

Thirty-three patients reached the main endpoint. By multivariate analysis, the only independent predictors of the endpoint were PDR (odds ratio [OR], 0.85; 95% confidence interval, 0.79-0.92) and international normalized ratio (OR, 1.45; 95% confidence interval, 1.17-1.82). A risk score weighted by the OR was built using cutoff values of 2.2 or greater for international normalized ratio (1 point) and less than 10%/min for PDR (2 points). Four categories (0 to 3) were possible. The risk of early death or retransplantation was associated with the score (0, 4.4%; 1, 6.5%; 2, 12%; and 3, 50%; χ for trend, P < 0.001). The score was also associated with duration of mechanical ventilation and intensive care unit stay. The score had a good diagnostic performance in the validation cohort (sensitivity, 60%; specificity, 95.5%; positive predictive value, 66.7%; negative predictive value, 94.1%).

CONCLUSIONS

A simple score obtained within the first day after LT predicts short-term survival and need for retransplantation and may prove useful when selecting diagnostic and therapeutic strategies.

The PRAISE study: a prospective, multi-center, randomized, double blinded, placebo-controlled study for the evaluation of iloprost in the early postoperative period after liver transplantation (ISRCTN12622749)

Background

Liver graft dysfunction can deteriorate to complete organ failure and increases perioperative morbidity and mortality after liver transplantation. Therapeutic strategies reducing the rate of graft dysfunction are of current clinical relevance. One approach is the systemic application of prostaglandins, which were demonstrated to be beneficial in reducing ischemia-reperfusion injury. Preliminary data indicate a positive effect of prostacyclin analogue iloprost on allograft viability after liver transplantation. The objective of the study is to evaluate the impact of iloprost in a multi-center trial.

Methods/Design

A prospective, double-blinded, randomized, placebo-controlled multicenter study in a total of 365 liver transplant recipients was designed to assess the effect of intravenous iloprost after liver transplantation. Primary endpoint will be the primary graft dysfunction characterized as presentation of one or more of the following criteria: ALAT or ASAT level > 2000 IU/ml within the first 7 postoperative days, bilirubine ≥ 10 mg/dl on postoperative day 7; INR ≥ 1.6 on postoperative day 7 or initial non-function. Secondary endpoints are parameters of post-transplant morbidity, like rates of infections, biliary complications, need of clotting factors or renal replacement therapy and the graft and patient survival.

Discussion

A well-established treatment concept to avoid graft dysfunction after liver transplantation does not exist at the moment. If the data of this research project confirm prior findings, iloprost would improve the general outcome after liver transplantation.

Trial Registration

German Clinical Trials Register: DRKS00003514. Current Controlled Trials Register: ISRCTN12622749.

Prostaglandins for adult liver transplanted patients

BACKGROUND

Prostaglandins may reduce ischaemic injury after liver transplantation. Several small randomised trials have evaluated the effects of prostaglandins in patients undergoing liver transplantation. Results of these trials are inconsistent, and none has enough power to reliably exclude effects of prostaglandins.

OBJECTIVES

To assess the benefits and harms of prostaglandin E1 or E2 in adult liver-transplanted patients.

SEARCH METHODS

We searched The Cochrane Hepato-Biliary Group Controlled Trials Register, the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library, MEDLINE, EMBASE, Science Citation Index Expanded, and LILACS (search on 20 April 2011). In addition, we perused the reference lists of the identified studies and contacted trials investigators, and national and international experts in order to identify more trials for the review.

SELECTION CRITERIA

We included randomised clinical trials evaluating prostaglandin E1 or E2 initiated in the perioperative period versus placebo or standard treatment for adult patients undergoing liver transplantation. We did not apply any language or publication status restrictions.

DATA COLLECTION AND ANALYSIS

Two authors independently evaluated methodological quality, ie, risk of bias of the included trials, and extracted data using standardised data extraction forms. We contacted trial investigators in attempt to retrieve information not available in the original manuscripts. We used random-effects model meta-analyses and fixed-effect model meta-analyses to estimate the odds ratio with 95% confidence interval (CI).

MAIN RESULTS

We included ten trials in which 652 patients were randomised. The risk of bias was considered high in most trials. There was no significant effect of prostaglandins on all-cause mortality (37/298[12.4%] in prostaglandin group versus 47/312[15.1%] in control group; OR 0.84, 95% CI 0.53 to 1.37; I(2) = 0%), on primary non-function of the allograft (8/238 [3.4%] versus. 16/250[6.4%] ;OR 0.55, 95% CI 0.23 to 1.33; I(2) = 0%), and on liver re-transplantation (12/161[7.5%] versus 14/171[8.2%]; OR 0.99, 95% CI 0.44 to 2.25; I(2) = 0%). Prostaglandins seemed to significantly decrease the risk of acute kidney failure requiring dialysis (13/158[8.2%] versus 34/171[9.9%]; OR 0.37, 95% CI 0.18 to 0.75; I(2) = 0%). There was no significant increase in the risk of adverse events with prostaglandins.

AUTHORS' CONCLUSIONS

We found no evidence that the administration of prostaglandins to liver transplanted patients reduces the risk of death, primary non-function of the allograft, or liver re-transplantation. Prostaglandins might reduce the risk of acute kidney failure requiring dialysis, but the quality of the evidence is considered only moderate due to high risk of bias in most of the included trials. Moreover, there are risks of outcome measure reporting bias and random errors. Therefore, further randomised, placebo-controlled trials are deemed necessary.

Impact of stable PGI₂ analog iloprost on early graft viability after liver transplantation: a pilot study

BACKGROUND

Ischemia/reperfusion injury after liver transplantation (LT) may be associated with primary graft dysfunction (PDF) or non-function. Prostaglandins were demonstrated to be beneficial in reducing ischemic injury by improving microcirculation and protecting endothelial cells. The aim of this study was to analyze the effect of the continuously administered prostaglandin I(2) analog iloprost on allograft function after LT.

METHODS

Eighty patients were prospectively randomized and assigned to two groups. Patients in the treatment group received iloprost for seven d after transplantation, and those in the control group did not. The primary end point was graft dysfunction.

RESULTS

The incidence of PDF was 20% (n = 8) in the control group and 5% (n = 2) in the treatment group, respectively (p = 0.087). Four patients in the control group underwent re-transplantation for initial non-function (INF). There was no evidence for INF in the treatment group. Iloprost was associated with improved allograft function. Clinical course and outcome were comparable.

CONCLUSIONS

We suggest iloprost to be beneficial for early post-transplant liver function. If the rate of PDF can be significantly reduced with this treatment concept, it should be analyzed in a larger number of patients (ISRCTN95672167).

Current protective strategies in liver surgery

During liver resection surgery for cancer or liver transplantation, the liver is subject to ischaemia (reduction in blood flow) followed by reperfusion (restoration of blood flow), which results in liver injury [ischemia-reperfusion (IR) or IR injury]. Modulation of IR injury can be achieved in various ways. These include hypothermia, ischaemic preconditioning (IPC) (brief cycles of ischaemia followed by reperfusion of the organ before the prolonged period of ischaemia i.e. a conditioning response), ischaemic postconditioning (conditioning after the prolonged period of ischaemia but before the reperfusion), pharmacological agents to decrease IR injury, genetic modulation of IR injury, and machine perfusion (pulsatile perfusion). Hypothermia decreases the metabolic functions and the oxygen consumption of organs. Static cold storage in University of Wisconsin solution reduces IR injury and has prolonged organ storage and improved the function of transplanted grafts. There is currently no evidence for any clinical advantage in the use of alternate solutions for static cold storage. Although experimental data from animal models suggest that IPC, ischaemic postconditioning, various pharmacological agents, gene therapy, and machine perfusion decrease IR injury, none of these interventions can be recommended in clinical practice. This is because of the lack of randomized controlled trials assessing the safety and efficacy of ischaemic postconditioning, gene therapy, and machine perfusion. Randomized controlled trials and systematic reviews of randomized controlled trials assessing the safety and efficacy of IPC and various pharmacological agents have demonstrated biochemical or histological improvements but this has not translated to clinical benefit. Further well designed randomized controlled trials are necessary to assess the various new protective strategies in liver resection.

[Solutions for organ preservation and other cardioplegic liquid formulations. Role of the hospital pharmacist]

Solid organ transplantation is an increasing need and a well-established activity which requires maintaining the quality of the transplant from procurement through the entire, storage, transport and graft procedure. Solutions for organ preservation play a key role in this procedure, by minimizing the deleterious effects of both ischemia and reperfusion. As such, their qualitative and quantitative compositions have to be optimized and validated. The development strategy and formulations proposed for these solutions are analyzed in this review as well as the results of the clinical studies which have set up the relevant pharmacological and physicochemical criteria. The French regulatory status of these products is also discussed. A clear distinction has to be made between solutions for organ preservation which are classified as produits thérapeutiques annexes (therapeutic ancillary products) and cardioplegic liquid formulations which are considered as medicinal products and are subject to marketing approval. Finally, the roles of the hospital pharmacist in the evaluation, selection, purchase and proper use of these products are described.

Prostacyclin in liver disease: a potential therapeutic option

Complex molecular and cellular mechanisms are involved in the initiation and progression of hepatic fibrosis. Recent studies have shown that hepatic stellate cells, endothelin, cytokines and prostacyclin play crucial roles in this pathology. Prostacyclin exerts vasorelaxant, antioxidant and antifibrotic properties that prevent the development of fibrosis and cirrhosis in liver diseases. In this editorial, the authors discuss some of the molecular and cellular mechanisms involved in the initiation and progression of liver fibrosis and the role played by prostacyclin in counteracting it. At the moment, however, only limited information is available from clinical studies demonstrating the effectiveness of prostacyclin in liver diseases and this makes it difficult to draw any conclusions; further efforts are necessary to verify whether prostacyclin, alone or in combination with other drugs, may be a valid therapeutic option in liver diseases.

Reperfusion injury in liver transplantation

Reperfusion injury occurring in the transplanted liver is a complex lesion and has been the focus of considerable research over the past decade. This section will review recent major developments in understanding the mechanisms involved and their application to clinical transplantation.

Prostacyclin in sepsis: A systematic review

According to current literature, infective processes greatly modify both vascular hemodynamics and anti-oxidant properties of affected tissues, causing a change in homeostasis that regulates the correct functioning of all cells responsible for the physiological and metabolic balance of various organs. As a consequence, the response to the infection that has caused the change is also likely to be weaker and, in the case of septic shock, ineffective. In this review, we will take into consideration these mechanisms and then focus on a group of vasodilator drugs (prostacyclin and its analogs) which, though have been used for over 20 years mainly to treat obstructive vascular diseases, have such hemodynamic and anti-inflammatory properties which prevent homeostatic changes. It is obvious that prostacyclin does not definitively have anti-infective characteristics; however, in association with anti-infective drugs (antibiotics, etc.), the effectiveness of the latter appears improved, at least in some circumstances. Similarly, the fact that prostacyclin and its analogs have a cytoprotective effect on the liver and reduce the ischemia-reperfusion damage following liver transplant is not a novelty and evidence that they improve hepatic hemodynamics suggests their use in those pathologies characterized by possible reduced perfusion or ascertained ischemia of the liver.