Mechanisms of autophagy activation in endothelial cell and their targeting during normothermic machine liver perfusion

Ischaemia-reperfusion injury(IRI) is the leading cause of injury seen in the liver following transplantation. IRI also causes injury following liver surgery and haemodynamic shock. The first cells within the liver to be injured by IRI are the liver sinusoidal endothelial cells(LSEC). Recent evidence suggests that LSEC coordinate and regulates the livers response to a variety of injuries. It is becoming increasingly apparent that the cyto-protective cellular process of autophagy is a key regulator of IRI. In particular LSEC autophagy may be an essential gatekeeper to the development of IRI. The recent availability of liver perfusion devices has allowed for the therapeutic targeting of autophagy to reduce IRI. In particular normothermic machine liver perfusion(NMP-L) allow the delivery of pharmacological agents to donor livers whilst maintaining physiological temperature and hepatic flow rates. In this review we summarise the current understanding of endothelial autophagy and how this may be manipulated during NMP-L to reduce liver IRI.

Liver graft preservation methods during cold ischemia phase and normothermic machine perfusion

The growing demand for donor organs requires measures to expand donor pool.Those include extended criteria donors, such as elderly people, steatotic livers,donation after cardiac death, etc. Static cold storage to reduce metabolic requirements developed by Collins in late 1960 s is the mainstay and the golden standard for donated organ protection. Hypothermic machine perfusion provides dynamic organ preservation at 4°C with protracted infusion of metabolic substrates to the graft during the ex vivo period. It has been used instead of static cold storage or after it as short perfusion in transplant center. Normothermic machine perfusion(NMP) delivers oxygen, and nutrition at physiological temperature mimicking regular environment in order to support cellular function. This would minimize effects of ischemia/reperfusion injury.Potentially, NMP may help to estimate graft functionality before implantation into a recipient. Clinical studies demonstrated at least its non-inferiority or better outcomes vs static cold storage. Regular grafts donated after brain death could be safely preserved with convenient static cold storage. Except for prolonged ischemia time where hypothermic machine perfusion started in transplant center could be estimated to provide possible positive reconditioning effect. Use of hypothermic machine perfusion in regular donation instead of static cold storage or in extended criteria donors requires further investigation. Multicenter randomized clinical trial supposed to be completed in December 2021. Extended criteria donors need additional measures for graft storage and assessment until its implantation. NMP is actively evaluating promising method for this purpose.Future studies are necessary for precise estimation and confirmation to issue clinical practice recommendations.

THE TECHNIQUE OF THE NORMOTHERMIC AND HYPOTHERMIC TOTAL HEPATIC VASCULAR EXCLUSION FOR RESECTION OF THE LIVER TUMORS

The technique for bloodless hepatic resection using the total hepatic vascular isolation under the normothermic or hypothermic perfusion was reported to deal with the large liver tumor involving in the liver hilum,the main hepatic veins or the retrohepatic vena cava.The original Heaney's and Fortner's methods were modified so that the technique could be simpler and more practicable to perform otherwise hazardous liver resection.During the past 4 year,major hepatic resection with the normothermic or hypothermic total vascular exclusion technique was successfully performed on 19 patients with liver tumors in our department.Among the 19 cases,16 underwent hepatic resection with the normothermic selective total vascular exclusion(extended right lobectomy in 5 cases,extended left lobectomy in 3 cases;right lobectomy in 5 cases;central segmentectomy in 3 cases)and 3 with the total vascular isolation and in situ cold perfusion(extended left lobectomy in 2 case,extended right lobectong in 1case).We believe that the technique of normothermic vascular exclusion may be indicated to deal with the lesion close to the hepatic veins and the retrohepatic vena cava.However,for more complicated hepatic resection,the hypothermic perfusion technique should be considered to prolong the safety of ischemic tune of the liver.The preliminary experience in the clinical application using the above technique is reported.

An Experience on Normothermic Beating Heart Pulmonary Thromboendarterectomy

Objective: To study the outcome of normothermic beating heart pulmonary thromboendarterectomy (PTE) performed in patients with chronic pulmonary thromboembolism. Methodology: A retrospective analysis of 15 patients who underwent PTE under normothermic beating heart cardio-pulmonary bypass from July 2009 to September 2018 was done. The patients were followed up with clinical assessment, transthoracic echocardiography and computerized tomographicangiography (CTA) for 1 month to 82 months. Results: Data were analysed for 15 consecutive patients. Mean age of the patients was 35.28 years and 10 patients were male. Pre-operatively 6 (40%) patients presented with New York Heart Association (NYHA) class II dyspnoea on exertion symptomatology, 7 (47%) were in NHYA class III, and 2 (13%) were in NYHA class IV. The preoperative and postoperative mean pulmonary artery pressures (mPAP) (mmHg) were 36.50 ± 11.3 and 20.21 ± 7.19, the systolic PAPs (mmHg) were 73.35 ± 14.12 and 35.21 ± 7.89 and the diastolic PAPs (mmHg) were 19.28 ± 8.60 and 12.85 ± 7.26 respectively. 2 (13%) patients had Jamieson’s type I and 12 (87%) had Jamieson type II disease. One patient (7%) expired on 9th postoperative day. All the patients had improved pulmonary gas exchange and did not require oxygen supplementation from 5th postoperative day;symptoms improved to NYHA class I & II in 12 (80%) & 3 (20%) of patients respectively. There was no reperfusion pulmonary edema or any neurologic complications. Postoperative echocardiogram showed improved right ventricular function and Computerised Tomographic Angiogram showed completeness of the procedure. Conclusion: Pulmonary thromboendarterectomy under normothermic beating heart cardiopulmonary bypass has good immediate postoperative results with significant progressive improvement in hemodynamics and quality of life during the course of follow-up. The results were not only comparable to those of the procedure done under deep hypothermic circulatory arrest by other centres but also without its associated adverse events. This technique requires more expertise but gives equivalent good results in immediate and short- to mid-term follow-up with less morbidity than the standard procedure, but it requires long-term follow-up to substantiate the evidence.

EXPERIENCE OF NORMOTHERMIC COMPLETE HEPATIC VASCULAR EXCLUSION FOR EXTENSIVE HEPATECTOMY (REPORT OF 4 CASES)

This paper deals with an experience of normothermic complete hepatic vascular exclusionfor extensive hepatectomy. All the 4 cases suffered from primary'llver carcinoma. In one case, thelarge tumor was situated in the left lobe, and the other tumor was situated in the left lobe, and in therest of them, the tumor even occupied the greater Part or the right lobe with one or the patient's inferior vena cave being Invaded by tumor seriously. Clamps were applied to the abdominal aorta, on theportal triads and to the inferior vena cave below and above the liver. Blood Intake during operationwas from 1000 to 1200 millilitres Hemodynareic alterations during hepatic vascular isolation wereslight and temporary. Biochemical alterations during operation we.re mainly metabolic acidosis. Postoperatively, serum bilirubin and serum enzymes elevation, total protein and albumin decrease werethe principal biological changes. The hepatic specimens weighed from 1400 to 1850 grams. This technique greatly reduced intraoperative hemorrhage, increased operative safety and raised the resectional rate of liver.

Biliary tract viability assessment and sequential hypothermic-normothermic perfusion in liver transplantation

We read with great interest the study of Mergental et al.(1)reporting the 5-year outcomes of the VITTAL trial(2,3).VITTAL was a prospective,non-randomized,single-arm trial that tested end-ischemic oxygenated normothermic machine perfusion(NMP)with a“back-to-base”strategy to evaluate,and potentially transplant,liver grafts declined by all liver transplantation(LT)centers in the United Kingdom.For a liver to be considered viable,it had to metabolize perfusate lactate to a concentration of≤2.5 mmol/L within four hours from the start of perfusion,and meet at least two of the following criteria:bile production without a defined quantity;maintenance of perfusate pH above 7.3;glucose consumption in the perfusate;maintenance of stable arterial and portal flow above 150 and 500 mL/min,respectively;maintenance of graft suppleness and homogeneous perfusion(4).Thirty-one discarded human donor livers underwent viability testing by using end-ischemic NMP,of which 22(71%)livers were subsequently transplanted.The primary outcome of the trial was graft survival rate at 90 days and it was 100%.

Long-term normothermic machine perfusion of fatty livers:towards transplanting untransplantable livers?

Since the very early days of clinical liver transplantation(LT),transplant surgeons and professionals have been confronted with the increased risk of failure associated with the use of fatty liver grafts(1).Notwithstanding the wide variability in steatosis assessment across different centers and pathologists(2),utilization of livers with moderate(≥30%)or severe(≥60%)macrovesicular steatosis has been consistently associated with an increased risk of primary non-function,early allograft dysfunction,acute kidney injury,as well as inferior graft and patient survival(3).The mechanisms behind the increased susceptibility of steatotic livers to ischemia-reperfusion injury(IRI)are multiple,including disturbances to microcirculation due to sinusoidal narrowing,increased oxidative stress upon reperfusion and enhanced lipid peroxidation,leading to an increased release of inflammatory mediators like IL6,IL1βand so-called damage associated molecular patterns(DAMP),like cell-free DNA and mitochondrial DNA.Histologically,this is reflected by hepatocyte death by necrosis rather than apoptosis,pseudopeliotic steatosis(i.e.,the expulsion of lipid droplets into the extracellular space)and lately,by tissue remodelling and fibrosis(4,5).

Normothermic regional perfusion mobile teams in controlled donation after circulatory death pathway: Evidence and peculiarities

To facilitate the implementation of controlled donation after circulatory death(cDCD)programs even in hospitals not equipped with a local Extracorporeal Membrane Oxygenation(ECMO)team(Spokes),some countries and Italian Regions have launched a local cDCD network with a ECMO mobile team who move from Hub hospitals to Spokes for normothermic regional perfusion(NRP)implantation in the setting of a cDCD pathway.While ECMO teams have been clearly defined by the Extracorporeal Life Support Organization,regarding composition,responsibilities and training programs,no clear,widely accepted indications are to date available for NRP teams.Although existing NRP mobile networks were developed due to the urgent need to increase the number of cDCDs,there is now the necessity for transplantation medicine to identify the peculiarities and responsibility of a NRP team for all those centers launching a cDCD pathway.Thus,in the present manuscript we summarized the character-istics of an ECMO mobile team,highlighting similarities and differences with the NRP mobile team.We also assessed existing evidence on NRP teams with the goal of identifying the characteristic and essential features of an NRP mobile team for a cDCD program,especially for those centers who are starting the program.Differences were identified between the mobile ECMO team and NRP mobile team.The common essential feature for both mobile teams is high skills and experience to reduce complications and,in the case of cDCD,to reduce the total warm ischemic time.Dedicated training programs should be developed for the launch of de novo NRP teams.

Comprehensive Approach to Assessment of Liver Viability During Normothermic Machine Perfusion

Liver transplantation is the most effective treatment of advanced liver disease,and the use of extended criteria donor organs has broadened the source of available livers.Although normothermic machine perfusion(NMP)has become a useful tool in liver transplantation,there are no consistent criteria that can be used to evaluate the viability of livers during NMP.This review summarizes the criteria,indicators,and methods used to evaluate liver viability during NMP.The shape,appearance,and hemodynamics of the liver can be analyzed at a macroscopic level,while markers of liver injury,indicators of liver and bile duct function,and other relevant indicators can be evaluated by biochemical analysis.The liver can also be assessed by tissue biopsy at the microscopic level.Novel methods for assessment of liver viability are introduced.The limitations of evaluating liver viability during NMP are discussed and suggestions for future clinical practice are provided.

Routine utilization of machine perfusion in liver transplantation:Ready for prime time?

The last decade has been notable for increasing high-quality research and dramatic improvement in outcomes with dynamic liver preservation.Robust evidence from numerous randomized controlled trials has been pooled by meta-analyses,providing the highest available evidence on the protective effect of machine perfusion(MP)over static cold storage in liver transplantation(LT).Based on a protective effect with less complications and improved graft survival,the field has seen a paradigm shift in organ preservation.This editorial focuses on the role of MP in LT and how it could become the new“gold standard”.Strong collaborative efforts are needed to explore its effects on long-term outcomes.

Machine perfusion and the prevention of ischemic type biliary lesions following liver transplant:What is the evidence?

The widespread uptake of different machine perfusion(MP)strategies for liver transplant has been driven by an effort to minimize graft injury.Damage to the cholangiocytes during the liver donation,preservation,or early posttransplant period may result in stricturing of the biliary tree and inadequate biliary drainage.This problem continues to trouble clinicians,and may have catastrophic consequences for the graft and patient.Ischemic injury,as a result of compromised hepatic artery flow,is a well-known cause of biliary strictures,sepsis,and graft failure.However,very similar lesions can appear with a patent hepatic artery and these are known as ischemic type biliary lesions(ITBL)that are attributed to microcirculatory dysfunction rather than main hepatic arterial compromise.Both the warm and cold ischemic period duration appear to influence the onset of ITBL.All of the commonly used MP techniques deliver oxygen to the graft cells,and therefore may minimize the cholangiocyte injury and subsequently reduce the incidence of ITBL.As clinical experience and published evidence grows for these modalities,the impact they have on ITBL rates is important to consider.In this review,the evidence for the three commonly used MP strategies(abdominal normothermic regional perfusion[A-NRP],hypothermic oxygenated perfusion[HOPE],and normothermic machine perfusion[NMP])for ITBL prevention has been critically reviewed.Inconsistencies with ITBL definitions used in trials,coupled with variations in techniques of MP,make interpretation challenging.Overall,the evidence suggests that both HOPE and A-NRP prevent ITBL in donated after circulatory death grafts compared to cold storage.The evidence for ITBL prevention in donor after brain death grafts with any MP technique is weak.

Liver preservation prior to transplantation: Past, present, and future

Since Dr. Thomas Starzl performed the first series of successful liver transplants(LTs), important advances have been made in immunosuppression, operative techniques, and postoperative care. In 1988, Belzer's group reported the first successful LT using the University of Wisconsin preservation solution(UW).Since then, UW has replaced EuroCollins solution and allowed prolonged and safer preservation of liver, kidney, and pancreas allografts, thus contributing to the improvement of transplant outcomes. Although UW is still considered the standard of care in the United States and in several countries worldwide, a recent meta-analysis revealed similar LT outcomes among UW, Celsior solution, and the Institut Georges Lopez-1 preservation solution, which were slightly superior to those obtained with histidine-tryptophan-ketoglutarate preservation solution.Dynamic preservation has been recently developed, and liver allografts are preserved mainly through the following methods: hypothermic machine perfusion, normothermic machine perfusion, and subnormothermic machine perfusion. Their use has the potential advantage of improving clinical results in LT involving extended criteria donor allografts. Although associated with increased costs, techniques employing machine perfusion of liver allografts have been considered clinically feasible. This editorial focuses on recent advances and future perspectives in liver allograft preservation.

Hepatic trisegmentectomy for 29 patients with huge liver neoplasms

Objective: To evaluate retrospectively the feasibility and effect of hepatic trisegmentectomy in therapy of huge neoplasms of the liver. Methods: From July 1993 to October 1999, 29 pa- tients with huge hepatic neoplasms underwent hepatic trisegmentectomy. Of these, 23 patients suffered from primary liver cancer, 1 hepatic infiltration of gallbladder cancer, 1 metastasis of colon cancer, 1 hepatic angiosarcoma, 1 hepatic neurofibroma, and 2 huge liver cysts. Twenty-six patients were subjected to right trisegmentectomy and the rest 3 left triseg- mentectomy. All trisegmentectomies were performed under normothermic interruption of the porta hepatis at single time and these interruptions lasted 15 to 40 minutes. Results: The relatively good effect was seen in our se- ries. The 1-, 3-, 5-year survival rates for primary liver cancer patients were 63.6%, 36.4% and 27.3 %, respectively. The survival period for the pa- tients with hepatic infiltration of gallbladder cancer and liver metastasis of colon cancer was 6 months. Those with hepatic angiosarcoma, hepatic neurofi- broma and huge liver cysts have been surviving 35, 26, 25 and 40 months, respectively. Major complica- tions were noted in 5 patients, and one (3.4%, 1/29) died. Conclusion: Hepatic trisegmentectomy is safe and ef- fective in treatment of huge hepatic neoplasms if its indications and operative techniques are properly mastered.

Metabolomic fingerprinting of porcine lung tissue during pre-clinical prolonged ex vivo lung perfusion using in vivo SPME coupled with LC-HRMS

Normothermic ex vivo lung perfusion(NEVLP)has emerged as a modernized organ preservation technique that allows for detailed assessment of donor lung function prior to transplantation.The main goal of this study was to identify potential biomarkers of lung function and/or injury during a prolonged(19 h)NEVLP procedure using in vivo solid-phase microextraction(SPME)technology followed by liquid chromatography-high resolution mass spectrometry(LC-HRMS).The use of minimally invasive in vivo SPME fibers for repeated sampling of biological tissue permits the monitoring and evaluation of biochemical changes and alterations in the metabolomic profile of the lung.These in vivo SPME fibers were directly introduced into the lung and were also used to extract metabolites(on-site SPME)from fresh perfusate samples collected alongside lung samplings.A subsequent goal of the study was to assess the feasibility of SPME as an in vivo method in metabolomics studies,in comparison to the traditional inlab metabolomics workflow.Several upregulated biochemical pathways involved in pro-and antiinflammatory responses,as well as lipid metabolism,were observed during extended lung perfusion,especially between the 11th and 12th hours of the procedure,in both lung and perfusate samples.However,several unstable and/or short-lived metabolites,such as neuroprostanes,have been extracted from lung tissue in vivo using SPME fibers.On-site monitoring of the metabolomic profiles of both lung tissues through in vivo SPME and perfusate samples on site throughout the prolonged NEVLP procedure can be effectively performed using in vivo SPME technology.

Liver transplantation with grafts obtained after cardiac death-current advances in mastering the challenge

The scarcity of donor livers has increased the interest in donation after cardiac death(DCD) as an additional pool to expand the availability of organs. However, the initial results of liver transplantation with DCD grafts have been suboptimal due to an increased rate of complications, as well as decreased graft survival. These challenges have led to many developments in DCD donation outcome, as well as basic and translational research. In this article we review the unique characteristics of DCD donors, nuances of DCD organ procurement, the effect of prolonged warm and cold ischemia times, and discuss major studies that compared DCD to donation after brain death liver transplantation, in terms of outcomes and complications. We also review the different methods of donor treatment that has been applied to ameliorate DCD organ outcome, and we discuss the role of machine perfusion techniques in organ reconditioning. We discuss the two major perfusionmodels, namely, hypothermic machine perfusion and normothermic machine perfusion; we compare both methods, and delineate their major differences.

Standardization is needed in reporting risk and outcomes of machine perfusion in liver transplantation

We congratulate Yamamoto et al.on their study“Impact of Portable Normothermic Machine Perfusion for Liver Transplantation from Adult Deceased Donors”(1).The surge of interest in normothermic machine perfusion(NMP)in the United States(US)has generated considerable enthusiasm.The authors present generally exciting results from their single-center analysis of 541 liver transplantations.Among these,469 were from donors after brain dead(DBD);58(12.4%)received NMP and 411 static cold storage(SCS,87.6%).Seventy-two transplants were from donors after circulatory death(DCD);52(72.2%)received NMP(device-to-donor)vs.20 SCS(27.8%).

Does ischemia-free machine perfusion lead to early allograft dysfunction (EAD) free liver transplantation?

Normothermic machine perfusion(NMP)is an innovative technique used in solid organ transplantation that involves perfusing the organ with specialized solution or leukocyte depleted red blood cells at near-normal body temperature aiming at mimicking physiological conditions,and providing optimal conditions for organ preservation which leads to reduced risk of ischemia reperfusion injury(IRI)when compared to the standard static cold storage(SCS)(1).One of the key advantages of NMP is its ability to assess the quality of the organ in real-time and assessment of the organ performance prior to transplantation.By continuously monitoring parameters such as blood flow,oxygen consumption,and lactate production,clinicians can evaluate the viability of the organ and make more informed decisions about its suitability for transplantation.This real-time assessment can help reduce the risk of transplanting organs that may not function optimally or have a higher likelihood of complications post-transplant.Additionally,NMP may expand the pool of donor organs by allowing for the use of organs that may have been deemed marginal or unsuitable for transplantation using traditional methods(1,2).

The conclusion of reducing acute rejection after liver transplantation by machine perfusion should be extrapolated with caution

There is a theory that the unavoidable graft damage caused by ischemia-reperfusion injury(IRI)during liver transplantation(LT)can lead to severe IRI-related inflammation and trigger an early activation of the innate immune response mediated by T-cells,which potentially worsening the acute cellular rejection(ACR)cascade.As a result,machine perfusion(MP)has been placed great expectations for the potential to diminish post-LT ACR and other related immune responses by alleviating IRI through removing harmful substances and restoring cellular metabolism homeostasis(1,2).However,there has been much debate about MP’s benefits on ACR as relative data is limited.

Gastric cancer: prevention and treatment of peritoneal metastases

Gastric cancer is an aggressive malignancy that may metastasize through the bloodstream to the liver,through lymphatics to regi onal lymph n odes,or by pen etratio n of the perit on eal lining of the stomach to result in seed ing of the abdom inal and pelvis surfaces.Peritoneal metastases are the most common mode of cancer dissemination.Technologies to prevent or treat perit on eal metastases from adva need gastric can cer are prese nted in this manu script.The world's literature,both recent and over the past three decades,was reviewed in order to identify publications that present information regarding gastric cancer peritoneal metastases.Over one dozen randomized controlled trials to test perioperative chemotherapy for prevention of peritoneal metastases were reviewed.All of the trials performed with regional chemotherapy during or shortly after gastrectomy were positive.The clinical data regarding the treatment of peritoneal metastases diagnosed at the time of primary can cer resecti on or in follow-up were reviewed.Neoadjuva nt in traperit on eal and systemic chemotherapy shows that some long-term survivors occur after these treatments were combined with cytoreductive surgery and gastrectomy.Similar treatments are advocated for primary gastric cancer with cytology positive for gastric cancer but no visible implants.Surgery for gastric cancer should be combined with perioperative systemic and regional chemotherapy in order to maximally benefit patients with this disease by reducing the negative impact of peritoneal metastases on survival.