Effect of Remote Ischemic Preconditioning Conducted in Living Liver Donors on Postoperative Liver Function in Donors and Recipients Following Liver Transplantation: A Randomized Clinical Trial. Ann Surg. 2020;271:646-653. [PMID: 31356262 DOI: 10.1097/sla.0000000000003498]

A Review of the Risk Factors and Approaches to Prevention of Post-Reperfusion Syndrome During Liver Transplantation

Post-reperfusion syndrome (PRS) is a severe and highly lethal syndrome that occurs after declamping the portal vein forceps during liver transplantation. It is marked by severe hemodynamic disturbances manifested by decreased mean arterial pressure, increased heart rate and elevated pulmonary artery pressure. The complex pathogenesis of PRS remains understudied. It is generally believed to be related to the large amount of acidic, cold blood that enters the circulation after release of the portal clamp. This blood is rich in oxygen-free radicals and metabolic toxins, which not only aggravate the ischemia-reperfusion injury of the liver but also further attack the systemic organs indiscriminately. Considering the range of possible adverse prognoses including acute kidney injury, delirium and graft nonfunction, it is imperative that clinicians increase their awareness and prevention of PRS. The aim of this article is to review the current risk factors, pathophysiological mechanisms and prevention strategies for PRS.

Better liver transplant outcomes by donor interventions?

PURPOSE OF REVIEW

Donor risk factors and events surrounding donation impact the quantity and quality of grafts generated to meet liver transplant waitlist demands. Donor interventions represent an opportunity to mitigate injury and risk factors within donors themselves. The purpose of this review is to describe issues to address among donation after brain death, donation after circulatory determination of death, and living donors directly, for the sake of optimizing relevant outcomes among donors and recipients.

RECENT FINDINGS

Studies on donor management practices and high-level evidence supporting specific interventions are scarce. Nonetheless, for donation after brain death (DBD), critical care principles are employed to correct cardiocirculatory compromise, impaired tissue oxygenation and perfusion, and neurohormonal deficits. As well, certain treatments as well as marginally prolonging duration of brain death among otherwise stable donors may help improve posttransplant outcomes. In donation after circulatory determination of death (DCD), interventions are performed to limit warm ischemia and reverse its adverse effects. Finally, dietary and exercise programs have improved donation outcomes for both standard as well as overweight living donor (LD) candidates, while minimally invasive surgical techniques may offer improved outcomes among LD themselves.

SUMMARY

Donor interventions represent means to improve liver transplant yield and outcomes of liver donors and grafts.

Effect of Remote Ischemic Conditioning on Organ Transplantation: A Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Remote ischemic conditioning (RIC) has shown great advantages in protecting organs from ischemia-reperfusion loss and applied research on RIC continues to increase. We performed a systematic review and meta-analysis to comprehensively investigate the value of RIC for different organ transplantation.

METHODS

We searched PubMed, EMBASE, and the Cochrane Library from inception to November 1, 2023, for randomized controlled trials investigating whether RIC has an advantage in organ transplantation (including heart, lung, liver, and kidney) compared with controls. The primary outcomes varied according to the transplanted organ, including liver transplantation (graft loss, early allograft dysfunction, acute kidney injury, days in hospital, and mortality); kidney transplantation (delayed graft function, acute rejection (AR), graft loss, 50% decrease in serum creatinine, glomerular filtration rate, days in hospital, and mortality); heart and lung transplantation (AR, mortality). Two investigators independently selected suitable trials, assessed trial quality, and extracted the data.

RESULTS

A total of 11 randomized controlled trials were included in this study, including six kidney transplants, three liver transplants, and one heart and lung transplant each, with 561 RIC cases and 564 controls, and a total of 1125 patients. The results showed that RIC did not reduce mortality in transplant patients compared with controls (liver transplant: RR0.9, 95% confidence interval [0.31-2.66]; kidney transplant: RR 0.76, 95% confidence interval [0.17-3.33]), graft failure rate (liver transplantation: RR 0.3, 95% confidence interval [0.07, 1.19]; kidney transplantation: RR 0.89, 95% confidence interval [0.35, 2.27]), length of hospital stay (liver transplantation: standard mean difference [SMD] 0.14, 95% confidence interval [-0.15, 0.42]; kidney transplantation: SMD -0.1, 95% confidence interval [-0.3, 0.11]). In addition, RIC did not improve early liver function after liver transplantation (RR 0.97, 95% confidence interval [0.55,1.7]), acute kidney injury after liver transplantation (RR 1.17 95% confidence interval [0.9, 1.54]), delayed functional recovery after renal transplantation (RR 0.84, 95% confidence interval [0.62, 1.15]), AR rate (RR 1.04, 95% confidence interval [0.72, 1.49]), 50% serum creatinine decline rate (RR 1.1, 95% confidence interval [0.88, 1.37]), glomerular filtration rate 3 months after surgery (SMD 0.13, 95% confidence interval [-0.05, 0.31]) and postoperative 12 months glomerular filtration rate (SMD 0.13, 95% confidence interval [-0.06, 0.31]).

CONCLUSION

Remote ischemic modulation does not improve clinical outcomes in patients undergoing organ transplantation (heart, lung, liver, and kidney).

Effect of dexmedetomidine on the incidence of postoperative acute kidney injury in living donor liver transplantation recipients: a randomized controlled trial

BACKGROUND

Acute kidney injury (AKI) is one of the most common complications after living-donor liver transplantation (LDLT) that has great impact on recipient and graft outcomes. Dexmedetomidine is reported to decrease the incidence of AKI. In the current study, the authors investigated whether intraoperative dexmedetomidine infusion would reduce the AKI following LDLT.

MATERIAL AND METHODS

In total, 205 adult patients undergoing elective LDLT were randomly assigned to the dexmedetomidine group ( n =103) or the control group ( n =102). Dexmedetomidine group received continuous dexmedetomidine infusion at a rate of 0.4 mcg/kg/h after the anesthesia induction until 2 h after graft reperfusion. The primary outcome was to compare the incidence of AKI. Secondary outcomes included serial lactate levels during surgery, chronic kidney disease, major adverse cardiovascular events, early allograft dysfunction, graft failure, overall mortality, duration of mechanical ventilation, intensive care unit, and hospital length of stay. Intraoperative hemodynamic parameters were also collected.

RESULTS

Of 205 recipients, 42.4% ( n =87) developed AKI. The incidence of AKI was lower in the dexmedetomidine group (35.0%, n =36/103) compared with the control (50.0%, n =51/102) ( P =0.042). There were significantly lower lactate levels in the dexmedetomidine group after reperfusion [4.39 (3.99-4.8) vs 5.02 (4.62-5.42), P =0.031] until the end of surgery [4.23 (3.73-4.74) vs 5.35 (4.84-5.85), P =0.002]. There were no significant differences in the other secondary outcomes besides lactate. Also, intraoperative mean blood pressure, cardiac output, and systemic vascular resistance did not show any difference.

CONCLUSION

Our study suggests that intraoperative dexmedetomidine administration was associated with significantly decreased AKI incidence and lower intraoperative serum lactate levels in LDLT recipients, without untoward hemodynamic effects.

Prediction of early recovery of graft function after living donor liver transplantation in children

For end-stage liver disease in children, living donor liver transplantation (LDLT) is often the important standard curative treatment. However, there is a lack of research on early recovery of graft function after pediatric LDLT. This is a single-center, ambispective cohort study. We collected the demographic and clinicopathological data of donors and recipients, and determined the risk factors of postoperative delayed recovery of hepatic function (DRHF) by univariate and multivariate Logistic analyses. 181 cases were included in the retrospective cohort and 50 cases in the prospective cohort. The incidence of DRHF after LDLT in children was 29.4%, and DRHF could well evaluate the early recovery of graft function after LDLT. Through Logistic analyses and AIC score, preoperative liver function of donors, ischemia duration level of the liver graft, Ln (Cr of recipients before operation) and Ln (TB of recipients on the 3rd day after operation) were predictive indicators for DRHF after LDLT in children. Using the above factors, we constructed a predictive model to evaluate the incidence of postoperative DRHF. Self-verification and prospective internal verification showed that this prediction model had good accuracy and clinical applicability. In conclusion, we pointed many risk factors for early delayed recovery of graft function after LDLT in children, and developed a visual and personalized predictive model for them, offering valuable insights for clinical management.

Effects of remote ischemic preconditioning in hepatectomy: a systematic review and meta-analysis

BACKGROUND

Animal experiments have confirmed that remote ischemic preconditioning (RIPC) can reduce hepatic ischemia-reperfusion injuries (HIRIs), significantly improving early tissue perfusion and oxygenation of the residual liver after resections, accelerating surgical prognoses, and improving survival rates. However, there is still controversy over the role of RIPC in relieving HIRI in clinical studies, which warrants clarification. This study aimed to evaluate the beneficial effects and applicability of RIPC in hepatectomy and to provide evidence-based information for clinical decision-making.

METHODS

Randomized controlled trials (RCTs) evaluating the efficacy and safety of RIPC interventions were collected, comparing RIPC to no preconditioning in patients undergoing hepatectomies. This search spanned from database inception to January 2024. Data were extracted independently by two researchers according to the PRISMA guidelines. The primary outcomes assessed were postoperative alanine transaminase (ALT), aspartate transaminase (AST), total bilirubin (TBIL), and albumin (ALB) levels. The secondary outcomes assessed included duration of surgery and Pringle, length of postoperative hospital stay, intraoperative blood loss and transfusion, indocyanine green (ICG) clearance, hepatocyte apoptosis index, postoperative complications, and others.

RESULTS

Ten RCTs were included in this meta-analysis, with a total of 865 patients (428 in the RIPC group and 437 in the control group). ALT levels in the RIPC group were lower than those in the control group on postoperative day (POD) 1 (WMD = - 59.24, 95% CI: - 115.04 to - 3.45; P = 0.04) and POD 3 (WMD = - 27.47, 95% CI: - 52.26 to - 2.68; P = 0.03). However, heterogeneities were significant (I2 = 89% and I2 = 78%), and ALT levels on POD 3 were unstable based on a sensitivity analysis. AST levels on POD 1 in the RIPC group were lower than those in the control group (WMD = - 50.03, 95% CI: - 94.35 to - 5.71; P = 0.03), but heterogeneity was also significant (I2 = 81%). A subgroup analysis showed no significant differences in ALT and AST levels on POD 1 between groups, regardless of whether the Pringle maneuver or propofol was used for anesthesia (induction only or induction and maintenance, P > 0.05). The remaining outcome indicators were not statistically significant or could not be analyzed due to lack of sufficient data.

CONCLUSION

RIPC has some short-term liver protective effects on HIRIs during hepatectomies. However, there is still insufficient evidence to encourage its routine use to improve clinical outcomes.

TRIAL REGISTRATION

The protocol of this study was registered with PROSPERO (CRD42022333383).

Remote ischemic preconditioning for reduction of ischemia-reperfusion injury after hepatectomy: A randomized sham-controlled trial

BACKGROUND

Remote ischemic preconditioning reduces ischemia-reperfusion injury in patients undergoing hepatectomy. Moreover, there is evidence that the protective effects of remote ischemic preconditioning may be more pronounced in pre-damaged livers. The objective of this trial was to investigate the extent to which remote ischemic preconditioning can attenuate ischemia-reperfusion injury after hepatectomy and Pringle maneuver in patients with chronic liver disease.

METHODS

In this randomized, controlled, triple-blind monocenter trial, a total of 102 patients with chronic liver disease and planned hepatectomy were enrolled between December 2019 and March 2022. Eligible patients were randomized to the remote ischemic preconditioning or sham arms. Remote ischemic preconditioning was induced through 3 10-minute cycles of alternating ischemia and reperfusion of the upper extremity. The study was prospectively registered in the German Clinical Trials Registry (DRKS00018931).

RESULTS

A total of 102 patients were included in the study and were randomized (51 per arm). The median age was 69.5 years, approximately two-thirds of the patients were male (69/102, 67.7%), and the mean body mass index was 25.6 kg/m2. Most patients were classified as American Society of Anesthesiologists II (55/102, 53.9%) or III (45/102, 44.1%). The primary endpoint, the transaminases on the first postoperative day (alanine aminotransferase /aspartate aminotransferase: remote ischemic preconditioning arm: 250 (35-1721)/320 (42-1525) U/L versus sham control arm: 283 (32-792)/356 (20-1851) U/L, P = .820/0.639), clinical outcomes as well as remote ischemic preconditioning biomarker levels were comparable between both arms.

CONCLUSION

Remote ischemic preconditioning did not achieve a significant reduction in postoperative transaminase levels, nor did it affect clinical results and biomarkers.

Routine End-ischemic Hypothermic Oxygenated Machine Perfusion in Liver Transplantation From Donors After Brain Death: A Randomized Controlled Trial

OBJECTIVE

To assess whether end-ischemic hypothermic oxygenated machine perfusion (HOPE) is superior to static cold storage (SCS) in preserving livers procured from donors after brain death (DBD).

BACKGROUND

There is increasing evidence of the benefits of HOPE in liver transplantation, but predominantly in the setting of high-risk donors.

METHODS

In this randomized clinical trial, livers procured from DBDs were randomly assigned to either end-ischemic dual HOPE for at least 2 hours or SCS (1:3 allocation ratio). The Model for Early Allograft Function (MEAF) was the primary outcome measure. The secondary outcome measure was 90-day morbidity (ClinicalTrials. gov, NCT04812054).

RESULTS

Of the 104 liver transplantations included in the study, 26 were assigned to HOPE and 78 to SCS. Mean MEAF was 4.94 and 5.49 in the HOPE and SCS groups ( P =0.24), respectively, with the corresponding rates of MEAF >8 of 3.8% (1/26) and 15.4% (12/78; P =0.18). Median Comprehensive Complication Index was 20.9 after transplantations with HOPE and 21.8 after transplantations with SCS ( P =0.19). Transaminase activity, bilirubin concentration, and international normalized ratio were similar in both groups. In the case of donor risk index >1.70, HOPE was associated with significantly lower mean MEAF (4.92 vs 6.31; P =0.037) and lower median Comprehensive Complication Index (4.35 vs 22.6; P =0.050). No significant differences between HOPE and SCS were observed for lower donor risk index values.

CONCLUSION

Routine use of HOPE in DBD liver transplantations does not seem justified as the clinical benefits are limited to high-risk donors.

Short-Term and Long-Term Effects of Ischemic Conditioning on Liver Transplantation: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Although liver transplantation (LT) is one of the definitive treatments for patients with end-stage liver failure, it inevitably results in ischemic reperfusion injury. It is known that prognosis is improved when temporary ischemic conditioning (IC) is applied to patients with ischemic reperfusion injury. The objective of this meta-analysis was to determine the short-term and long-term effects of IC on the clinical outcomes of LT recipients.

METHODS

Randomized controlled studies on IC in patients with LTs were included. Patients were compared between an IC group and a sham group. Studies were retrieved from PubMed, Embase, and Cochrane Library. The risk of bias was evaluated using RoB 2.0. Mortality, graft function, and major complications were synthesized using RevMan 5.4.1.

RESULTS

Among 316 papers, 17 articles (1196 patients) were included. There was an insignificant increase in short-term mortality (risk ratio [RR]: 3.00, 95% CI: 0.32-28.14, P = .34). However, long-term mortality was lower in the IC group than in the sham group, but not significantly (RR: 0.75; 95% CI: 0.47-1.20, P = .23). Short-term graft function (acute graft rejection and primary graft non-function) was not improved by IC. One-year graft loss tended to show better results in the IC group (RR: 0.53, 95% CI: 0.26-1.07, P = .08).

CONCLUSION

Ischemic conditioning did not have a beneficial effect on LT. Although long-term outcomes appear to be better in the IC group than in the sham group, further randomized controlled trials are needed.

Ischemic preconditioning attenuates endoplasmic reticulum stress-dependent apoptosis of hepatocytes by regulating autophagy in hepatic ischemia-reperfusion injury

Hepatic ischemia-reperfusion injury (HIRI) usually occurs during subtotal hepatectomy and severely damages liver function during the perioperative period. Endoplasmic reticulum stress (ERS) dependent apoptosis has been suggested to play a crucial role in HIRI progression. The present study focused on the regulatory effect of autophagy activation induced by ischemic preconditioning (IPC) on ERS-dependent apoptosis of hepatocytes in HIRI. A HIRI mouse model and oxygen-glucose deprivation/reperfusion (OGD/R) AML-12 hepatocyte cell lines were constructed to evaluate the protective effect of IPC in vivo and in vitro. The protein levels of p-eIF2α, CHOP, and cleaved caspase-12 were used to evaluate the ERS-dependent apoptosis, whereas LC3-II and p62 were considered as the autophagy activation markers. The beneficial molecular chaperones GRP78, HSP60, and HSP70 were also tested to evaluate autophagy. HIRI significantly increased ERS-dependent apoptosis markers and the number of apoptotic cells and damaged liver function. The ERS inhibitor salubrinal significantly alleviated liver injury in HIRI and OGD/R hepatocytes. Furthermore, both remote IPC and direct IPC significantly alleviated liver injury and inflammatory cell infiltration. IPC also upregulated LC3-II, downregulated p62 expression, and increased the mRNA levels of GRP78, HSP60, and HSP70 in HIRI mice and OGD/R hepatocytes, indicating the activation of autophagy by IPC. The autophagy inhibitor 3-methyladenine significantly attenuated the protective effects of IPC on ERS-dependent apoptosis and liver function, whereas the autophagy activator rapamycin mimicked the protective effects of IPC on ERS-dependent apoptosis in vivo and in vitro, suggesting a regulatory role of autophagy in ERS-dependent apoptosis. These results demonstrated that IPC could induce moderate autophagy and upregulate a few molecular chaperones to strengthen endogenous defense mechanisms, which is beneficial for alleviating ERS-dependent apoptosis and protecting hepatocytes from HIRI.

FOXO1 regulates Th17 cell-mediated hepatocellular carcinoma recurrence after hepatic ischemia-reperfusion injury

BACKGROUND

Hepatic ischemia-reperfusion injury (IRI) is considered as an effecting factor for hepatocellular carcinoma (HCC) recurrence. Th17/Treg cells are a pair of essential components in adaptive immune response in liver IRI, and forkhead box O1 (FOXO1) has the properties of maintaining the function and phenotype of immune cells. Herein, we illuminated the correlation and function between Th17/Treg cell balance and FOXO1 in IRI-induced HCC recurrence.

METHODS

RNA sequencing was performed on naive CD4+ T cells from normal and IRI model mice to identify relevant transcription factors. Western blotting, qRT-PCR, immunohistochemical staining, and flow cytometry were performed in IRI models to indicate the effect of FOXO1 on the polarization of Th17/Treg cells. Then, transwell assay of HCC cell migration and invasion, clone formation, wound healing assay, and Th17 cells adoptively transfer was utilized to assess the function of Th17 cells in IRI-induced HCC recurrence in vitro and in vivo.

RESULTS

Owning to the application of RNA sequencing, FOXO1 was screened and assumed to perform a significant function in hepatic IRI. The IRI model demonstrated that up-regulation of FOXO1 alleviated IR stress by attenuating inflammatory stress, maintaining microenvironment homeostasis, and reducing the polarization of Th17 cells. Mechanistically, Th17 cells accelerated IRI-induced HCC recurrence by shaping the hepatic pre-metastasis microenvironment, activating the EMT program, promoting cancer stemness and angiogenesis, while the upregulation of FOXO1 can stabilize the liver microenvironment homeostasis and alleviate the negative effects of Th17 cells. Moreover, the adoptive transfer of Th17 cells in vivo revealed its inducing function in IRI-induced HCC recurrence.

CONCLUSIONS

These results indicated that FOXO1-Th17/Treg axis exerts a crucial role in IRI-mediated immunologic derangement and HCC recurrence, which could be a promising target for reducing the HCC recurrence after hepatectomy. Liver IRI affects the balance of Th17/Treg cells by inhibiting the expression of FOXO1, and the increase of Th17 cells has the ability to induce HCC recurrence through EMT program, cancer stemness pathway, the formation of premetastatic microenvironment and angiogenesis.

Impacts of ischemic preconditioning in liver resection: systematic review with meta-analysis

OBJECTIVE

To assess the beneficial effects of ischemic preconditioning (IPC) in liver resection and evaluate its applicability in clinical practice.

SUMMARY BACKGROUND DATA

Liver surgeries are usually associated with intentional transient ischemia for hemostatic control. IPC is a surgical step that intends to reduce the effects of ischemia-reperfusion; however, there is no strong evidence about the real impact of the IPC, and it is necessary to effectively clarify what its effects are.

METHODS

Randomized clinical trials were selected, comparing IPC with no preconditioning in patients undergoing liver resection. Data were extracted by three independent researchers according to the PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) guidelines, Supplemental Digital Content 1, http://links.lww.com/JS9/A79 . Several outcomes were evaluated, including postoperative peaks of transaminases and bilirubin, mortality, length of hospital stay, length of stay in the ICU, bleeding, and transfusion of blood products, among others. Bias risks were assessed using the Cochrane collaboration tool.

RESULTS

Seventeen articles were selected, with a total of 1052 patients. IPC did not change the surgical time of the liver resections while these patients bled less (Mean Difference: -49.97 ml; 95% CI: -86.32 to -13.6; I2 : 64%), needed less blood products [relative risk (RR): 0.71; 95% CI: 0.53-0.96; I2 =0%], and had a lower risk of postoperative ascites (RR: 0.40; 95% CI: 0.17-0.93; I2 =0%). The other outcomes had no statistical differences or could not have their meta-analyses conducted due to high heterogeneity.

CONCLUSIONS

IPC is applicable in clinical practice, and it has some beneficial effects. However, there is not enough evidence to encourage its routine use.

Hepatocyte-derived extracellular vesicles miR-122-5p promotes hepatic ischemia reperfusion injury by regulating Kupffer cell polarization

Ischemia reperfusion injury remains a major barrier to liver transplantation, especially using grafts from donation after circulatory death, and it is also a pressing issue to be solved in clinical practice. Kupffer cell polarization toward a proinflammatory M1 phenotype is an early trigger of liver ischemia-reperfusion injury. However, the molecular mechanism regulating Kupffer cell polarization has not yet been fully elucidated. We induced liver ischemia reperfusion injury in mice and obtained samples from patients undergoing liver transplantation, serum and hepatocytes-derived extracellular vesicles were isolated by differential ultracentrifugation. Kupffer cell polarization was examined by flow cytometry and immunofluorescence histochemistry. RNA-seq was conducted to detect the differentially expressed miRNAs in extracellular vesicles. The role and mechanism of exosomal miR-122-5p in liver ischemia-reperfusion injury were determined both in vitro and in vivo. We identified ischemia reperfusion induced extracellular vesicles as a major cause of hepatic inflammation and tissue damage using adoptive transfer and release inhibition. The study also demonstrated that hepatocyte-derived exosomal miR-122-5p mediates liver ischemia reperfusion injury by polarizing Kupffer cell via PPARδ down-regulation and NF-κB pathway activation using profiling and functional analysis. Moreover, inhibiting miR-122-5p with antagomir suppressed Kupffer cell M1 polarization and attenuated liver ischemia reperfusion injury. Overall, our study demonstrated that hepatocyte-derived exosomal miR-122-5p played a critical role in promoting hepatic ischemia reperfusion injury through modulating PPARδ signaling and NF-κB pathway to introduce M1 polarization of Kupffer cell. Inhibition of miR-122-5p exhibited a protective effect against liver ischemia reperfusion injury, suggesting a potential therapeutic target for liver transplantation.

Efficacy of remote ischaemic preconditioning on outcomes following non-cardiac non-vascular surgery: a systematic review and meta-analysis

BACKGROUND

Remote ischaemic preconditioning (RIPC) has been investigated as a simple intervention to potentially mitigate the ischaemic effect of the surgical insult and reduce postoperative morbidity. This review systematically evaluates the effect of RIPC on morbidity, including duration of hospital stay and parameters reflective of cardiac, renal, respiratory, and hepatic dysfunction following non-cardiac non-vascular (NCNV) surgery.

METHODS

The electronic databases PubMed, Embase, and the Cochrane Central Register of Controlled Trials (CENTRAL) were searched from their inception date to November 2021. Studies investigating the effect of local preconditioning or postconditioning were excluded. Methodological quality and risk of bias were determined according to the Revised Cochrane risk-of-bias tool for randomised trials (RoB 2). Calculation of the odds ratios and a random effects model was used for dichotomous outcomes and mean differences or standardised mean differences as appropriate were used for continuous outcomes. The primary outcomes of interest were cardiac and renal morbidity, and the secondary outcomes included other organ function parameters and hospital length of stay.

RESULTS

A systematic review of the published literature identified 36 randomised controlled trials. There was no significant difference in postoperative troponin or acute kidney injury. RIPC was associated with lower postoperative serum creatinine (9 studies, 914 patients, mean difference (MD) - 3.81 µmol/L, 95% confidence interval (CI) - 6.79 to - 0.83, p = 0.01, I² = 5%) and lower renal stress biomarker (neutrophil gelatinase-associated lipocalin (NGAL), 5 studies, 379 patients, standardized mean difference (SMD) - 0.66, 95% CI - 1.27 to - 0.06, p = 0.03, I² = 86%). RIPC was also associated with improved oxygenation (higher P_aO₂/F_iO₂, 5 studies, 420 patients, MD 51.51 mmHg, 95% CI 27.32 to 75.69, p < 0.01, I² = 89%), lower biomarker of oxidative stress (malondialdehyde (MDA), 3 studies, 100 patients, MD - 1.24 µmol/L, 95% CI - 2.4 to - 0.07, p = 0.04, I² = 91%)) and shorter length of hospital stay (15 studies, 2110 patients, MD - 0.99 days, 95% CI - 1.75 to - 0.23, p = 0.01, I² = 88%).

CONCLUSIONS

This meta-analysis did not show an improvement in the primary outcomes of interest with the use of RIPC. RIPC was associated with a small improvement in certain surrogate parameters of organ function and small reduction in hospital length of stay. Our results should be interpreted with caution due to the limited number of studies addressing individual outcomes and the considerable heterogeneity identified.

TRIAL REGISTRATION

PROSPERO CRD42019129503.

Aging deteriorated liver Ischemia and reperfusion injury by suppressing Tribble's proteins 1 mediated macrophage polarization

Aggravated liver injury has been reported in aged ischemia/reperfusion-stressed livers; however, the mechanism of aged macrophage inflammatory regulation is not well understood. Here, we found that the adaptor protein TRIB1 plays a critical role in the differentiation of macrophages and the inflammatory response in the liver after ischemia/reperfusion injury. In the present study, we determined that aging promoted macrophage-mediated liver injury and that inflammation was mainly responsible for lower M2 polarization in liver transplantation-exposed humans post I/R. Young and aged mice were subjected to hepatic I/R modeling and showed that aging aggravated liver injury and suppressed macrophage TRIB1 protein expression and anti-inflammatory function in I/R-stressed livers. Restoration of TRIB1 is mediated by lentiviral infection-induced macrophage anti-inflammatory M2 polarization and alleviated hepatic I/R injury. Moreover, TRIB1 overexpression in macrophages facilitates M2 polarization and anti-inflammation by activating MEK1-ERK1/2 signaling under IL-4 stimulation. Taken together, our results demonstrated that aging promoted hepatic I/R injury by suppressing TRIB1-mediated MEK1-induced macrophage M2 polarization and anti-inflammatory function.

Perioperative management of living donor liver transplantation: Part 2 - Donors

Living donor liver transplantation was first developed to mitigate the limited access to deceased donor organs in Asia in the 1990s. This alternative liver transplantation method has become a widely practiced and established transplantation option for adult patients suffering with end-stage liver disease, and it has successfully helped address the shortage of deceased donors. The Society for the Advancement of Transplant Anesthesia and the Korean Society of Transplantation Anesthesiologists jointly reviewed published studies on the perioperative management of adult live liver donors undergoing donor hemi-hepatectomy. The goal of the review is to offer transplant anesthesiologists and critical care physicians a comprehensive overview of the perioperative management of adult live donors. We featured the current status, donor selection process, outcomes and complications, surgical procedure, anesthetic management, Enhanced Recovery After Surgery protocols, avoidance of blood transfusion, and considerations for emergency donation. Recent surgical advances, including laparoscopic donor hemi-hepatectomy and robotic laparoscopic donor surgery, are also addressed.

Integrative omics reveals subtle molecular perturbations following ischemic conditioning in a porcine kidney transplant model

BACKGROUND

Remote Ischemic Conditioning (RIC) has been proposed as a therapeutic intervention to circumvent the ischemia/reperfusion injury (IRI) that is inherent to organ transplantation. Using a porcine kidney transplant model, we aimed to decipher the subclinical molecular effects of a RIC regime, compared to non-RIC controls.

METHODS

Kidney pairs (n = 8 + 8) were extracted from brain dead donor pigs and transplanted in juvenile recipient pigs following a period of cold ischemia. One of the two kidney recipients in each pair was subjected to RIC prior to kidney graft reperfusion, while the other served as non-RIC control. We designed an integrative Omics strategy combining transcriptomics, proteomics, and phosphoproteomics to deduce molecular signatures in kidney tissue that could be attributed to RIC.

RESULTS

In kidney grafts taken out 10 h after transplantation we detected minimal molecular perturbations following RIC compared to non-RIC at the transcriptome level, which was mirrored at the proteome level. In particular, we noted that RIC resulted in suppression of tissue inflammatory profiles. Furthermore, an accumulation of muscle extracellular matrix assembly proteins in kidney tissues was detected at the protein level, which may be in response to muscle tissue damage and/or fibrosis. However, the majority of these protein changes did not reach significance (p < 0.05).

CONCLUSIONS

Our data identifies subtle molecular phenotypes in porcine kidneys following RIC, and this knowledge could potentially aid optimization of remote ischemic conditioning protocols in renal transplantation.

Association of skeletal muscle index with postoperative acute kidney injury in living donor hepatectomy: A retrospective single-centre cohort study

BACKGROUND

Although living donor liver transplantation (LDLT) is the standard treatment option for patients with end-stage liver disease, it always entails ethical concerns about the risk of living donors. Recent studies have reported a correlation between sarcopenia and surgical prognosis in recipients. However, there are few studies of donor sarcopenia and the surgical prognosis of donors. This study investigated the association between sarcopenia and postoperative acute kidney injury in liver donors.

METHODS

This retrospective study analysed 2892 donors who underwent donor hepatectomy for LDLT between January 2008 and January 2018. Sarcopenia was classified into pre-sarcopenia and severe sarcopenia, which were determined to be -1 standard deviation (SD), and -2 SD from the mean baseline of the skeletal muscle index, respectively. Multivariate regression analysis was performed to evaluate the association between donor sarcopenia and postoperative AKI. Additionally, we assessed the association between donor sarcopenia and delayed recovery of liver function (DRHF).

RESULTS

In the multivariate analysis, donor sarcopenia was significantly associated a higher incidence of postoperative AKI (adjusted odds ratio [OR]: 2.65, 95% confidence interval [CI]: 1.15-6.11, P = .022 in pre-sarcopenia, OR: 5.59, 95% CI: 1.11-28.15, P = .037 in severe sarcopenia, respectively). Additionally, hypertension and synthetic colloid use were significantly associated with postoperative AKI. In the multivariate analysis, risk factors of DRHF were male gender, indocyanine green retention rate at 15 minutes, and graft type, however, donor sarcopenia was not a risk factor.

CONCLUSIONS

Donor sarcopenia is associated with postoperative AKI following donor hepatectomy.

Novel Targets and Therapeutic Strategies to Protect Against Hepatic Ischemia Reperfusion Injury

Hepatic ischemia reperfusion injury (IRI), a fascinating topic that has drawn a lot of interest in the last few years, is a major complication caused by a variety of clinical situations, such as liver transplantation, severe trauma, vascular surgery, and hemorrhagic shock. The IRI process involves a series of complex events, including mitochondrial deenergization, metabolic acidosis, adenosine-5'-triphosphate depletion, Kupffer cell activation, calcium overload, oxidative stress, and the upregulation of pro-inflammatory cytokine signal transduction. A number of protective strategies have been reported to ameliorate IRI, including pharmacological therapy, ischemic pre-conditioning, ischemic post-conditioning, and machine reperfusion. However, most of these strategies are only at the stage of animal model research at present, and the potential mechanisms and exact therapeutic targets have yet to be clarified. IRI remains a main cause of postoperative liver dysfunction, often leading to postoperative morbidity or even mortality. Very recently, it was reported that the activation of peroxisome proliferator-activated receptor γ (PPARγ), a member of a superfamily of nuclear transcription factors activated by agonists, can attenuate IRI in the liver, and FAM3A has been confirmed to mediate the protective effect of PPARγ in hepatic IRI. In addition, non-coding RNAs, like LncRNAs and miRNAs, have also been reported to play a pivotal role in the liver IRI process. In this review, we presented an overview of the latest advances of treatment strategies and proposed potential mechanisms behind liver IRI. We also highlighted the role of several important molecules (PPARγ, FAM3A, and non-coding RNAs) in protecting against hepatic IRI. Only after achieving a comprehensive understanding of potential mechanisms and targets behind IRI can we effectively ameliorate IRI in the liver and achieve better therapeutic effects.

The hepatoprotective effect from ischemia-reperfusion injury of remote ischemic preconditioning in the liver related surgery: a meta-analysis

BACKGROUND

This study aimed to assess the hepatoprotective effect of remote ischemic preconditioning (RIPC) in the liver related surgery.

METHODS

Published articles in PubMed, Embase and Cochrane clinical trial databases were searched from the inception to May 2021. Randomized control trials (RCTs) comparing the RIPC with control or other conditionings were included for analysis. The postoperative liver synthetic function was used as the primary outcome.

RESULTS

A total of six RCTs were included the present meta-analysis. There were 216 patients underwent RIPC and 212 patients in the control group. The RIPC group had a significantly lower level of postoperative alanine transaminase and aspartate transaminase (p<0.001). The postoperative bilirubin level was also significant lower in the RIPC group than the control group (MD = -9.0, 95%CI, -13.94 to -4.03; p<0.001). ICG clearance was reduced in controls versus RIPC (p<0.001). There was no significant difference between the RIPC and control group in terms of the complication rate.

CONCLUSION

The RIPC was evaluated to have a strong hepatoprotective effect from ischemia-reperfusion injury in the liver related surgery.

Ischemic Preconditioning for Liver Transplantation: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Background

In recent decades, liver transplantation (LTx) has increased the survival and quality of life of patients with end-stage organ failure. Unfortunately, LTx is limited due to the shortage of donors. A lot of effort is put into finding new ways to reduce ischemia-reperfusion injury (IRI) in liver grafts to increase the number of suitable organs procured from expanded-criteria donors (ECD). The aim of this study was to systematically review the literature reporting LTx outcomes when using ischemic preconditioning (IPC) or remote ischemic preconditioning (RIPC) to reduce IRI in liver grafts.

Methods

A literature search was performed in the MEDLINE, Web of Science, and EMBASE databases. The following combination was used: "Liver" OR "Liver Transplantation" AND "Ischemic preconditioning" OR "occlusion" OR "clamping" OR "Pringle." The following outcome data were retrieved: the rates of graft primary nonfunction (PNF), retransplantation, graft loss, and mortality; stay in hospital and the intensive care unit; and postoperative serum liver damage parameters.

Results

The initial search retrieved 4,522 potentially relevant studies. After evaluating 17 full-text articles, a total of 9 randomized controlled trials (RCTs) were included (7 IPC and 2 RIPC studies) in the qualitative synthesis; the meta-analysis was only performed on the data from the IPC studies. RIPC studies had considerable methodological differences. The meta-analysis revealed the beneficial effect of IPC when comparing postoperative aspartate aminotransferase (AST) corresponding to a statistically lower mortality rate in the IPC group (odds ratio [OR] 0.51; 95% confidence interval [CI] 0.27-0.98; p = 0.04).

Conclusion

IPC lowers postoperative AST levels and reduces the mortality rate; however, data on the benefits of RIPC are lacking.

Ischemic postconditioning reduces spinal cord ischemia-reperfusion injury through ATP-sensitive potassium channel

STUDY DESIGN

Animal study.

OBJECTIVES

Explore the neuroprotective effect of remote limb ischemic postconditioning (Post C) in spinal cord ischemic reperfusion injury (SCII) and related mechanisms.

SETTING

Anesthesiology Laboratory of Southwest Medical University.

METHODS

We established a rabbit SCII model and processed it with Post C. To evaluate the neural function, spinal cord tissue was taken 48 h later, normal neurons were evaluated by HE staining, and the expression of ATP-sensitive potassium channel (K_ATP) marker molecule Kir6.2 was detected by Western blot. Immunofluorescence detection of spinal cord Iba-1 expression, ELISA detection of M1 type microglia marker iNOS and M2 type microglia marker Arg, and Western blot detection of NF-κB and IL-1β expression. Through these experiments, we will explore the protective effect of Post C in SCII, observe the changes in the protective effect after using K_ATP blockers, and verify that Post C can play a neuroprotective effect in SCII by activating K_ATP.

RESULTS

We observed that Post C significantly improved exercise ability and the number of spinal motor neurons in the SCII model. Microglia are activated and expression of M₁ microglia in the spinal cord was decreased, while M₂ was increased. This neuroprotective effect was reversed by the nonspecific K_ATP inhibitor.

CONCLUSION

Post C has a neuroprotective effect on SCII, and maybe a protective effect produced by activating K_ATP to regulate spinal microglia polarization and improve neuroinflammation.

Effect of Remote Ischemic Conditioning on Bleeding Complications in Surgery: A Systematic Review and Meta-Analysis

Remote ischemic conditioning (RIC) is administered with an inflatable tourniquet by inducing brief, alternating cycles of limb ischemia and reperfusion. RIC possibly impacts the hemostatic system, and the intervention has been tested as protective therapy against ischemia-reperfusion injury and thrombotic complications in cardiac surgery and other surgical procedures. In the present systematic review, we aimed to investigate the effect of RIC on intraoperative and postoperative bleeding complications in meta-analyses of randomized controlled trials including adult patients undergoing surgery. A systematic search was performed on November 7, 2020 in PubMed, Embase, and the Cochrane Central Register of Controlled Trials. Randomized controlled trials comparing RIC versus no RIC in adult patients undergoing surgery that reported bleeding outcomes in English publications were included. Effect estimates with 95% confidence intervals were calculated using the random-effects model for intraoperative and postoperative bleeding outcomes. Thirty-two randomized controlled trials with 3,804 patients were eligible for inclusion. RIC did not affect intraoperative bleeding volume (nine trials; 392 RIC patients, 399 controls) with the effect estimate -0.95 [-9.90; 7.99] mL (p = 0.83). RIC significantly reduced postoperative drainage volume (seven trials; 367 RIC patients, 365 controls) with mean difference -83.6 [-134.9; -32.4] mL (p = 0.001). The risk of re-operation for bleeding was reduced in the RIC group (16 trials; 838 RIC patients, 839 controls), albeit not significantly, with the relative risk 0.65 [0.39; 1.09] (p = 0.10). In conclusion, RIC reduced postoperative bleeding measured by postoperative drainage volume in this meta-analysis of adult patients undergoing surgery.

Methods of Attenuating Ischemia-Reperfusion Injury in Liver Transplantation for Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is one of the most frequent indications for liver transplantation. However, the transplantation is ultimately associated with the occurrence of ischemia-reperfusion injury (IRI). It affects not only the function of the graft but also significantly worsens the oncological results. Various methods have been used so far to manage IRI. These include the non-invasive approach (pharmacotherapy) and more advanced options encompassing various types of liver conditioning and machine perfusion. Strategies aimed at shortening ischemic times and better organ allocation pathways are still under development as well. This article presents the mechanisms responsible for IRI, its impact on treatment outcomes, and strategies to mitigate it. An extensive review of the relevant literature using MEDLINE (PubMed) and Scopus databases until September 2020 was conducted. Only full-text articles written in English were included. The following search terms were used: “ischemia reperfusion injury”, “liver transplantation”, “hepatocellular carcinoma”, “preconditioning”, “machine perfusion”.

Direct, remote and combined ischemic conditioning in liver surgery

Liver ischemia-reperfusion injury is a major cause of postoperative liver dysfunction, morbidity and mortality following liver resection and transplantation. Ischemic conditioning has been shown to ameliorate ischemia-reperfusion injury in small animal models. It can be applied directly or remotely when cycles of ischemia and reperfusion are applied to a distant site or organ. Considering timing of the procedure, different protocols are available. Ischemic preconditioning refers to that performed before the duration of ischemia of the target organ. Ischemic perconditioning is performed over the duration of ischemia of the target organ. Ischemic postconditioning applies brief episodes of ischemia at the onset of reperfusion following a prolonged ischemia. Animal studies pointed towards suppressing cytokine release, enhancing the production of hepatoprotective adenosine and reducing liver apoptotic response as the potential mechanisms responsible for the protective effect of direct tissue conditioning. Interactions between neural, humoral and systemic pathways all lead to the protective effect of remote ischemic preconditioning. Despite promising animal studies, none of the aforementioned protocols proved to be clinically effective in liver surgery with the exception of morbidity reduction in cirrhotic patients undergoing liver resection. Further human clinical trials with application of novel conditioning protocols and combination of methods are warranted before implementation of ischemic conditioning in day-to-day clinical practice.

Effect of remote ischaemic preconditioning on mortality and morbidity after non-cardiac surgery: meta-analysis

BACKGROUND

Remote ischaemic preconditioning (RIPC) has been shown to have a protective role on vital organs exposed to reperfusion injury. The aim of this systematic review was to evaluate the effects of non-invasive RIPC on clinical and biochemical outcomes in patients undergoing non-cardiac surgery.

METHODS

A systematic literature search of PubMed, EMBASE, Scopus, and Cochrane databases was carried out in February 2020. RCTs investigating the effect of non-invasive RIPC in adults undergoing non-cardiac surgery were included. Meta-analyses and trial sequential analyses (TSAs) were performed on cardiovascular events, acute kidney injury, and short- and long-term mortality.

RESULTS

Some 43 RCTs including 3660 patients were included. The surgical areas comprised orthopaedic, vascular, abdominal, pulmonary, neurological, and urological surgery. Meta-analysis showed RIPC to be associated with fewer cardiovascular events in non-cardiac surgery (13 trials, 1968 patients, 421 events; odds ratio (OR) 0.68, 95 per cent c.i. 0.47 to 0.96; P = 0.03). Meta-analyses of the effect of RIPC on acute kidney injury (12 trials, 1208 patients, 211 events; OR 1.14, 0.78 to 1.69; P = 0.50; I2 = 9 per cent), short-term mortality (7 trials, 1239 patients, 65 events; OR 0.65, 0.37 to 1.12; P = 0.12; I2 = 0 per cent), and long-term mortality (4 trials, 1167 patients, 9 events; OR 0.67, 0.18 to 2.55; P = 0.56; I2 = 0 per cent) showed no significant differences for RIPC compared with standard perioperative care in non-cardiac surgery. However, TSAs showed that the required information sizes have not yet been reached.

CONCLUSION

Application of RIPC to non-cardiac surgery might reduce cardiovascular events, but not acute kidney injury or all-cause mortality, but currently available data are inadequate to confirm or reject an assumed intervention effect.

Effect of remote ischemic preconditioning among donors and recipients following pediatric liver transplantation: A randomized clinical trial

BACKGROUND

Studies suggested that remote ischemic preconditioning (RIPC) may effectively lessen the harmful effects of ischemia reperfusion injury during organ transplantation surgery.

AIM

To investigate the protective effects of RIPC on living liver donors and recipients following pediatric liver transplantation.

METHODS

From January 2016 to January 2019 at Renji Hospital Affiliated with Shanghai Jiao Tong University School of Medicine, 208 donors were recruited and randomly assigned to four groups: S-RIPC group (no intervention; n = 55), D-RIPC group (donors received RIPC; n = 51), R-RIPC group (recipients received RIPC, n = 51) and DR-RIPC group (both donors and recipients received RIPC; n = 51). We primarily evaluated postoperative liver function among donors and recipients and incidences of early allograft dysfunction, primary nonfunction and postoperative complications among recipients.

RESULTS

RIPC did not significantly improve alanine transaminase and aspartate aminotransferase levels among donors and recipients or decrease the incidences of early allograft dysfunction, primary nonfunction, and postoperative complications among recipients. Limited protective effects were observed, including a lower creatinine level in the D-RIPC group than in the S-RIPC group on postoperative day 0 (P < 0.05). However, no significant improvements were found in donors who received RIPC. Furthermore, RIPC had no effects on the overall survival of recipients.

CONCLUSION

The protective effects of RIPC were limited for recipients who received living liver transplantation, and no significant improvement of the prognosis was observed in recipients.

Randomised sham-controlled double-blind trial evaluating remote ischaemic preconditioning in solid organ transplantation: a study protocol for the RIPTRANS trial

INTRODUCTION

Remote ischaemic preconditioning (RIPC) using a non-invasive pneumatic tourniquet is a potential method for reducing ischaemia-reperfusion injury. RIPC has been extensively studied in animal models and cardiac surgery, but scarcely in solid organ transplantation. RIPC could be an inexpensive and simple method to improve function of transplanted organs. Accordingly, we aim to study whether RIPC performed in brain-dead organ donors improves function and longevity of transplanted organs.

METHODS AND ANALYSES

RIPTRANS is a multicentre, sham-controlled, parallel group, randomised superiority trial comparing RIPC intervention versus sham-intervention in brain-dead organ donors scheduled to donate at least one kidney. Recipients of the organs (kidney, liver, pancreas, heart, lungs) from a randomised donor will be included provided that they give written informed consent. The RIPC intervention is performed by inflating a thigh tourniquet to 300 mm Hg 4 times for 5 min. The intervention is done two times: first right after the declaration of brain death and second immediately before transferring the donor to the operating theatre. The sham group receives the tourniquet, but it is not inflated. The primary endpoint is delayed graft function (DGF) in kidney allografts. Secondary endpoints include short-term functional outcomes of transplanted organs, rejections and graft survival in various time points up to 20 years. We aim to show that RIPC reduces the incidence of DGF from 25% to 15%. According to this, the sample size is set to 500 kidney transplant recipients.

ETHICS AND DISSEMINATION

This study has been approved by Helsinki University Hospital Ethics Committee and Helsinki University Hospital's Institutional Review Board. The study protocol was be presented at the European Society of Organ Transplantation congress in Copenhagen 14-15 September 2019. The study results will be submitted to an international peer-reviewed scientific journal for publication.

TRIAL REGISTRATION NUMBER

NCT03855722.

Remote Ischemic Preconditioning in a Cirrhotic Patient Undergoing Major Hepatectomy

Remote ischemic preconditioning (RIPC) has been shown to reduce ischemic reperfusion injury for patients undergoing hepatectomy for colorectal liver metastasis. We present a case of a 69-year-old male who underwent right hepatectomy for a multifocal hepatocellular carcinoma of the right liver and concomitant liver cirrhosis (Child-Pugh stage A). We performed portal vein embolization prior to surgery and intraoperative RIPC of the iliac vessels. The postoperative course after major hepatectomy went uneventful.

Essential updates 2018/2019: Liver transplantation

Among the recent topics in the field of liver transplantation (LT), one of the significant therapeutic breakthroughs is the introduction of direct-acting antiviral agents (DAAs) against hepatitis C virus (HCV) infection. With cure rates close to 100%, a better proportion of LT candidates and recipients can be cured of HCV infection by DAA therapies that are simple and well-tolerated. Other critical topics include the issue of indication of LT for patients with hepatocellular carcinoma, which has been continuously studied. Several expanded criteria beyond the Milan criteria with acceptable results have been recently reported. The role of donor-specific antibodies (DSAs) in intractable rejection is also an important matter that has been studied. Although long recognized as an important factor in antibody-mediated rejection and even graft survival in renal transplantation, the impact of DSAs on graft and patient survival in LT remains to be elucidated. Including the issues described above, this article focuses on recent advances in LT, management to avoid recurrence of primary diseases, optimization of immunosuppressive treatment, and extended donor criteria.