Decrease Ischemia-reperfusion Injury Research Articles

Machine Perfusion as a Strategy to Decrease Ischemia-Reperfusion Injury and Lower Cancer Recurrence Following Liver Transplantation.

Liver transplantation (LT) is a key treatment for primary and secondary liver cancers, reducing tumor burden with concurrent improvement of liver function. While significant improvement in survival is noted with LT, cancer recurrence rates remain high. Mitochondrial dysfunction caused by ischemia-reperfusion injury (IRI) is known to drive tumor recurrence by creating a favorable microenvironment rich in pro-inflammatory and angiogenic factors. Therefore, strategies that decrease reperfusion injury and mitochondrial dysfunction may also decrease cancer recurrence following LT. Machine perfusion techniques are increasingly used in routine clinical practice of LT with improved post-transplant outcomes and increased use of marginal grafts. Normothermic (NMP) and hypothermic oxygenated machine perfusion (HOPE) provide oxygen to ischemic tissues, and impact IRI and potential cancer recurrence through different mechanisms. This article discussed the link between IRI-associated inflammation and tumor recurrence after LT. The current literature was screened for the role of machine perfusion as a strategy to mitigate the risk of cancer recurrence. Upfront NMP ("ischemia free organ transplantation") and end-ischemic HOPE were shown to reduce hepatocellular carcinoma recurrence in retrospective studies. Three prospective randomized controlled trials are ongoing in Europe to provide robust evidence on the impact of HOPE on cancer recurrence in LT.

Cardiomyocyte-specific beta3-adrenergic receptor expression reduces infarct size inhibiting the autophagic flux in mice

Abstract Background Since the discovery of β3-adrenergic receptor (β3AR), the third class of β-adrenergic receptors, expression in in both cardiomyocytes and endothelial cells of the cardiovascular system, it has come to the focus due to it´s possible implication in cardiovascular diseases. Although it´s expression is low compared to β1 and β2 subtypes (1), its been demonstrated that β3AR agonists have a cardioprotective effect in ischemia/reperfusion (IR) injury though inhibition of mitochondrial pore opening (2). Purpose In this project we determined the cellular origin of the β3AR cardioprotection and its role on cellular autophagic machinery. Methods Mice with overexpression of the β3AR in cardiomyocytes or endothelial cells and their control littermates were subjected to left coronary artery occlusion for 45 min followed reperfusion after 24h and 7days. Left ventricular function was assessed by echocardiography at day 7. Then, heart samples were collected at baseline and 24h and 7 days after IRI. Mitochondrial number were analyzed by transmission electron microscopy. Proteins related to autophagy signaling pathways were measured by western blot and RT-qPCR. Results Cardiomyocyte-specific β3AR overexpression protects the heart upon IR injury, reduced cardiac fibrosis which improved cardiac function and maintained heart mass. Studying the effects at baseline to understand the molecular mechanisms of cardioprotection, we found that β3AR overexpression in cardiomyocytes showed a reduction in autophagy markers such as LC3B and Parkin, meaning there is an alteration in the autophagic flux. Conclusions Cardiomyocyte-specific overexpression of β3-adrenergic receptor reduces infarct size and protects the heart affecting the autophagy machinery. Our results shed light on the role of the β3AR in the mitochondrial quality control system, offering evidence of its potential use as a target to decrease IR injury in patients with acute myocardial infarction.

Targeting succinate metabolism to decrease brain injury upon mechanical thrombectomy treatment of ischemic stroke

Current treatments for acute ischemic stroke aim to reinstate a normal perfusion in the ischemic territory but can also cause significant ischemia-reperfusion (IR) injury. Previous data in experimental models of stroke show that ischemia leads to the accumulation of succinate, and, upon reperfusion, the accumulated succinate is rapidly oxidized by succinate dehydrogenase (SDH) to drive superoxide production at mitochondrial complex I. Despite this process initiating IR injury and causing further tissue damage, the potential of targeting succinate metabolism to minimize IR injury remains unexplored. Using both quantitative and untargeted high-resolution metabolomics, we show a time-dependent accumulation of succinate in both human and mouse brain exposed to ischemia ex vivo. In a mouse model of ischemic stroke/mechanical thrombectomy mass spectrometry imaging (MSI) shows that succinate accumulation is confined to the ischemic region, and that the accumulated succinate is rapidly oxidized upon reperfusion. Targeting succinate oxidation by systemic infusion of the SDH inhibitor malonate upon reperfusion leads to a dose-dependent decrease in acute brain injury. Together these findings support targeting succinate metabolism upon reperfusion to decrease IR injury as a valuable adjunct to mechanical thrombectomy in ischemic stroke.

Customized normothermic machine perfusion decreases ischemia-reperfusion injury compared with static cold storage in a porcine model of liver transplantation.

Liver transplantation has been demonstrated to be the best treatment for several liver diseases, while grafts are limited. This has caused an increase in waiting lists, making it necessary to find ways to expand the number of organs available for transplantation. Normothermic perfusion (NMP) of liver grafts has been established as an alternative to static cold storage (SCS), but only a small number of perfusion machines are commercially available. Using a customized ex situ machine perfusion, we compared the results between ex situ NMP and SCS preservation in a porcine liver transplant model. During NMP, lactate concentrations were 80% lower after the 3-h perfusion period, compared with SCS. Bile production had a 2.5-fold increase during the NMP period. After transplantation, aspartate transaminase (AST) and alanine transaminase (ALT) levels were 35% less in the NMP group, compared to the SCS group. In pathologic analyses of grafts after transplant, tissue oxidation did not change between groups, but the ischemia-reperfusion injury score was lower in the NMP group. NMP reduced hepatocellular damage and ischemia-reperfusion injury when compared to SCS using a customized perfusion machine. This could be an alternative for low-income countries to include machine perfusion in their therapeutic options.

TFNR2 in Ischemia-Reperfusion Injury, Rejection, and Tolerance in Transplantation.

Tumor necrosis factor receptor 2 (TNFR2) has been shown to play a crucial role in CD4+ T regulatory cells (CD4+Tregs) expansion and suppressive function. Increasing evidence has also demonstrated its role in a variety of immune regulatory cell subtypes such as CD8+ T regulatory cells (CD8+ Tregs), B regulatory cells (Bregs), and myeloid-derived suppressor cells (MDSCs). In solid organ transplantation, regulatory immune cells have been associated with decreased ischemia-reperfusion injury (IRI), improved graft survival, and improved overall outcomes. However, despite TNFR2 being studied in the context of autoimmune diseases, cancer, and hematopoietic stem cell transplantation, there remains paucity of data in the context of solid organ transplantation and islet cell transplantation. Interestingly, TNFR2 signaling has found a clinical application in islet transplantation which could guide its wider use. This article reviews the current literature on TNFR2 expression in immune modulatory cells as well as IRI, cell, and solid organ transplantation. Our results highlighted the positive impact of TNFR2 signaling especially in kidney and islet transplantation. However, further investigation of TNFR2 in all types of solid organ transplantation are required as well as dedicated studies on its therapeutic use during induction therapy or treatment of rejection.

Large-Animal Model of Donation after Circulatory Death and Normothermic Regional Perfusion for Cardiac Assessment

The increase in demand for cardiac transplantation throughout the years has fueled interest in donation after circulatory death (DCD) to expand the organ donor pool. However, the DCD process is associated with the risk of cardiac tissue injury due to the inevitable period of warm ischemia. Normothermic regional perfusion (NRP) allows for an in situ organ assessment, allowing the procurement of hearts determined to be viable. Here, we describe a clinically relevant large-animal model of DCD followed by NRP. Circulatory death is established in anesthetized pigs by stopping mechanical ventilation. After a preset warm ischemia period, an extracorporeal membrane oxygenator (ECMO) is used for a NRP period lasting at least 30 min. During this reperfusion period, the model allows the collection of various myocardial biopsies and blood samples for initial cardiac evaluation. Once NRP is weaned, biochemical, hemodynamic, and echocardiographic assessments of cardiac function and metabolism can be performed before organ procurement. This protocol closely simulates the clinical scenario previously described for DCD and NRP in heart transplantation and has the potential to facilitate studies aimed at decreasing ischemia-reperfusion injury and enhance cardiac functional preservation and recovery.

Large-Animal Model of Donation after Circulatory Death and Normothermic Regional Perfusion for Cardiac Assessment.

The increase in demand for cardiac transplantation throughout the years has fueled interest in donation after circulatory death (DCD) to expand the organ donor pool. However, the DCD process is associated with the risk of cardiac tissue injury due to the inevitable period of warm ischemia. Normothermic regional perfusion (NRP) allows for an in situ organ assessment, allowing the procurement of hearts determined to be viable. Here, we describe a clinically relevant large-animal model of DCD followed by NRP. Circulatory death is established in anesthetized pigs by stopping mechanical ventilation. After a preset warm ischemia period, an extracorporeal membrane oxygenator (ECMO) is used for a NRP period lasting at least 30 min. During this reperfusion period, the model allows the collection of various myocardial biopsies and blood samples for initial cardiac evaluation. Once NRP is weaned, biochemical, hemodynamic, and echocardiographic assessments of cardiac function and metabolism can be performed before organ procurement. This protocol closely simulates the clinical scenario previously described for DCD and NRP in heart transplantation and has the potential to facilitate studies aimed at decreasing ischemia-reperfusion injury and enhance cardiac functional preservation and recovery.

Custodiol® Supplemented with Synthetic Human Relaxin Decreases Ischemia-Reperfusion Injury after Porcine Kidney Transplantation.

Objective. Ischemia-reperfusion injury (IRI) is inevitable after kidney transplantation (KT), impairing outcomes. Relaxin-2 (RLX) is a promising insulin-related peptide hormone that protects against renal IRI in rodents, although large animal models are needed before RLX can be tested in a human setting. Methods. In this blinded, randomized, and placebo-controlled experimental study kidneys from 19 donor pigs were retrieved after perfusion with Custodiol® ± RLX (5 or 20 nmol/L) and underwent static cold storage (SCS) for 24 and 48 h, respectively. Subsequently, KT was performed after unilateral right nephrectomy. Study outcomes included markers for kidney function, oxidative stress, lipid peroxidation, and endothelial cell damage. PCR analysis for oxidative stress and apoptosis-related gene panels as well as immunohistochemistry were performed. Results. RLX upregulated SOD2 and NFKB expression to 135% (p = 0.042) and 125% (p = 0.019), respectively, while RIPK1 expression was downregulated to 82% (p = 0.016) of corresponding controls. Further RLX significantly downregulated RIPK1 and MLKL expression and decreased the number of Caspase 3- and MPO-positive cells in grafts after SCS. Conclusions. RLX supplemented Custodiol® significantly decreased IRI via both antioxidant and anti-apoptotic mechanisms. Clinical trials are warranted to implement synthetic human RLX as a novel additive to preservation solutions against IRI.

Resveratrol Confers Protection Against Ischemia/Reperfusion Injury by Increase of Angiotensin (1-7) Expression in a Rat Model of Myocardial Hypertrophy.

Left ventricular hypertrophy (LVH) makes the heart vulnerable to ischemia/reperfusion (IR) injury. Angiotensin (Ang) (1-7) is recognized as a cardioprotective peptide. We investigated the effect of polyphenol resveratrol on myocardial IR injury after hypertrophy and examined cardiac content of Ang (1-7) and transcription of its receptor (MasR). Rats were divided into sham-operated, LVH, IR, LVH + IR, and resveratrol + LVH + IR groups. Myocardial hypertrophy and IR models were created by abdominal aortic banding and left coronary artery occlusion, respectively. To evaluate the electrocardiogram parameters and incidence of arrhythmias, electrocardiogram was recorded by subcutaneous leads (lead II). Blood pressure was measured through the left carotid artery. Infarct size was determined by the triphenyl tetrazolium chloride staining. The Ang (1-7) level was evaluated by immunohistochemistry. The Mas receptor mRNA level was assessed by the real-time real time reverse transcription polymerase chain reaction technique. QT-interval duration, infarct size, and incidence of ischemia-induced arrhythmia were significantly higher in the LVH + IR group. However, in the resveratrol-treated group, these parameters were decreased significantly. The cardiac level of Ang (1-7) was decreased in untreated hypertrophied hearts (LVH and LVH + IR groups). Pretreatment with resveratrol normalized the cardiac level of Ang (1-7). The mRNA level of Mas receptor was increased in all of hypertrophied hearts in the presence or absence of resveratrol. Resveratrol can decrease IR injury in rats with LVH. The anti-ischemic effect of resveratrol may be related to the enhancement of Ang (1-7)/MasR axis.

Delayed graft function and perfusion parameters of kidneys from uncontrolled donors after circulatory death.

Better preservation and evaluation of kidneys from donors after circulatory death serve to increase the number of kidneys available for transplantation and hypothermic machine perfusion has been shown to decrease ischemia reperfusion injury and delayed graft function. Data on relation between hemodynamic parameters during hypothermic machine perfusion and delayed graft function in kidneys from donors after circulatory death are so far scarce and not univocal. We aimed at assessing whether hemodynamic parameters measured during hypothermic machine perfusion (flow, mean perfusion pressure, and renal resistance) are associated with delayed graft function in 26 kidneys retrieved from uncontrolled donors after circulatory death. In our series, the incidence of delayed graft function was 57.7% (15/26). Recipients who developed delayed graft function had a longer warm ischemic time (p = 0.04). All hemodynamic parameters measured during hypothermic machine perfusion were comparable between recipients with delayed graft function and those without. According to our data, in kidneys from uncontrolled donors after circulatory death, a longer warm ischemic time (that is the overall time of no flow, as the sum of the no-flow and the no-touch period) is associated with delayed graft function. This finding underscores the pivotal role of ischemic injury in terms of absence of flow in affecting graft function. No association was detectable between hemodynamic parameters during hypothermic machine perfusion and the development of delayed graft function in our series.

Nitric Oxide Inhalation is Associated with Decreased Incidence of Acute Rejection after Cardiac Transplantation

Inhaled nitric oxide (iNO) has been shown to decrease ischemia-reperfusion injury (IRI) by several putative mechanisms, while preclinical studies have shown it to reduce acute rejections. In heart transplantation (HTx), iNO is routinely used to decrease pulmonary vascular resistance. However, iNO's effect on IRI after HTx and later outcomes on acute rejections remains unknown. We performed post hoc analysis on clinical data and plasma samples of 84 donor-recipient pairs collected in a prospective, double-blinded single-center trial. Recipient plasma was collected prior to HTx, and 1, 6, 12, and 24h after transplantation. In addition cardiac biopsies were collected before and 1h after reperfusion, and 2 weeks after HTx. We measured TnT, TnI, CKMBm, and proBNP as biomarkers for early organ-specific injury and function. Follow-up was conducted until one year for rejections and mortality. Of the 84 patients, 58.3% received iNO after HTx based on perioperative pulmonary vascular resistance. Preoperatively, iNO-treated patients had higher bilirubin and proBNP (P<0.01 and P<0.05), and a trend for higher transpulmonary gradient (P=0.058). Postoperatively, iNO-treated patients had higher TnT, TnI, and proBNP plasma levels (P<0.01-0.05), and an increased need for renal replacement therapy (P<0.001) compared to patients not receiving iNO. iNO-treated patients received more likely ATG, and therefore patients were divided to subgroups based on ATG and iNO treatment. In a 1-year follow-up, mortality between groups was similar. In groups without ATG treatment, iNO-treated patients had fewer biopsy-proven acute rejection episodes, and their 1-y freedom from rejection was higher (20% vs 52%) (both P<0.01). There was a similar, albeit statistically non-significant, trend for groups receiving ATG. iNO-treated patients were sicker pre- and postoperatively compared to patients not receiving iNO. Despite iNO-patients being overall sicker, iNO-treatment associated with less rejections. Our findings suggest that iNO may have some long-term cardioprotective effects after HTx. In ISHLT 2020 meeting we aim to present also results on the effect of iNO on early inflammatory cell influx to the graft, and on changes in cardiac transcriptome using IHC and next-generation sequencing from cardiac biopsies.

Stimulation of soluble guanylate cyclase improves donor organ function in rat heart transplantation

Heart transplantation remains the definitive therapy of end-stage heart failure. Ischemia-reperfusion injury occurring during transplantation is a primary determinant of long-term outcome of heart transplantation and primary graft insufficiency. Modification of the nitric oxide/soluble guanylate cyclase/cyclic guanosine monophosphate signaling pathway appears to be one of the most promising among the pharmacological interventional options. We aimed at characterizing the cardio-protective effects of the soluble guanylate cyclase stimulator riociguat in a rat model of heterotopic heart transplantation. Donor Lewis rats were treated orally with either riociguat or placebo for two days (n = 9) in each transplanted group and (n = 7) in donor groups. Following explantation, hearts were heterotopically transplanted. After one hour reperfusion, left ventricular pressure-volume relations and coronary blood flow were recorded. Molecular biological measurements and histological examination were also completed. Left ventricular contractility (systolic pressure: 117 ± 13 vs. 48 ± 5 mmHg, p < 0.001; dP/dtmax: 2963 ± 221 vs. 1653 ± 159 mmHg/s, p < 0.001), active relaxation (dP/dtmin: −2014 ± 305 vs. −1063 ± 177 mmHg/s, p = 0.02; all at 120 µl of left ventricular volume), and alteration of coronary blood flow standardized to heart weight (2.55 ± 0.32 vs. 1.67 ± 0.22 ml/min/g, p = 0.03) were markedly increased following preconditioning with riociguat. Myocardial apoptosis markers were also significantly reduced in the riociguat pretreated group as well as the antioxidant markers were elevated. Pharmacological preconditioning with riociguat decreases ischemia-reperfusion injury and improves donor organ function in our animal model of heart transplantation. Therefore, riociguat might be a potential cardioprotective agent.

EX SITU HEART PERFUSION IMPROVES PRESERVATION OF ENDOTHELIAL FUNCTION IN BOTH DBD AND DCD HEARTS

Purpose Ex situ heart perfusion (ESHP) decreases ischemic time and improves myocardial preservation for transplantation. However, the effects of machine perfusion on endothelial function has not yet been determined. We aimed to compare coronary vasomotor function and endothelial activation following transplantation between hearts donated after circulatory death (DCD) and controls (beating-heart donations) preserved in cold storage or ESHP Methods DCD pigs underwent hypoxic circulatory arrest via asphyxiation followed by 15min of warm ischemia . Both DCD and control hearts were preserved with either 3h of cold storage or 4h of ESHP. Following transplantation, both groups were reperfused for 3h. We assessed coronary artery segments for endothelial-dependent (Edep) and -independent (Eind) relaxation, and sensitivity to vasospasm using a small vessel myograph. Expression of VCAM-1 , and endothelin receptors A (ETa) and B (ETb) were measured with immunoblotting Results Preservation with ESHP partially improved Edep (p=0.098) and significantly enhanced Eind (p=0.004) in controls. DCD hearts showed no differences in Edep (p=0.266), Eind (p=0.182) compared to controls when preserved in cold storage. Preservation of DCD hearts using ESHP significantly improved Edep (p Conclusion ESHP strategies have enabled DCD heart transplantation and expansion of the donor heart pool. Limiting cold ischemia by machine perfusion with a normothermic, oxygenated, and blood-based perfusate seems to limit endothelial activation and dysfunction by decreasing ischemia-reperfusion injury . This may lead to a reduced rate of early graft dysfunction and late development of allograft vasculopathy

Pre-clinical Model of Cardiac Donation after Circulatory Death.

Cardiac transplantation demand is on the rise; nevertheless, organ availability is limited due to a paucity of suitable donors. Organ donation after circulatory death (DCD) is a solution to address this limited availability, but due to a period of prolonged warm ischemia and the risk of tissue injury, its routine use in cardiac transplantation is seldom seen. In this manuscript we provide a detailed protocol closely mimicking current clinical practices in the context of DCD with continuous monitoring of heart function, allowing for the evaluation of novel cardioprotective strategies and interventions to decrease ischemia-reperfusion injury. In this model, the DCD protocol is initiated in anesthetized Lewis rats by stopping ventilation to induce circulatory death. When systolic blood pressure drops below 30 mmHg, the warm ischemic time is initiated. After a pre-set warm ischemic period, hearts are flushed with a normothermic cardioplegic solution, procured, and mounted onto a Langendorff ex vivo heart perfusion system. Following 10 min of initial reperfusion and stabilization, cardiac reconditioning is continuously evaluated for 60 min using intraventricular pressure monitoring. A heart injury is assessed by measuring cardiac troponin T and the infarct size is quantified by histological staining. The warm ischemic time can be modulated and tailored to develop the desired amount of structural and functional damage. This simple protocol allows for the evaluation of different cardioprotective conditioning strategies introduced at the moment of cardioplegia, initial reperfusion and/or during ex vivo perfusion. Findings obtained from this protocol can be reproduced in large models, facilitating clinical translation.

Effect of dexmedetomidine on ischemia-reperfusion injury of liver and kidney tissues in experimental diabetes and hepatic ischemia-reperfusion injury induced rats

Background: Reperfusion following ischemia can lead to more injuries than ischemia itself especially in diabetic patients. The aim of this study was to evaluate the effect of dexmedetomidine on ischemia-reperfusion injury (IRI) in rats with have hepatic IRI and diabetes mellitus.

Ex-vivo perfusion as a successful strategy for reduction of ischemia-reperfusion injury in prolonged muscle flap preservation – A gene expression study

IntroductionWith the introduction of vascularized composite allotransplantation (VCA) as new surgical technique, the need arose for strategies that could safely prolong graft preservation. Ex-vivo machine perfusion is a promising technique and is currently applied in solid organ transplantation. There is still limited evidence in the field of VCA and free flap transplantation. This gene expression study aimed to assess the degree of ischemia-reperfusion (IR) injury after preservation and replantation of free muscle flaps in a porcine model. Materials and methodsA microarray analysis was first conducted on muscle flaps preserved by ex-vivo perfusion versus cold storage, to select genes of interest for further investigation. The expression of these selected genes was then examined in a muscle flap replantation model after 18 hour ex-vivo perfusion (n = 14) using qRT-PCR. Two preservation solutions were compared to static cold storage: University of Wisconsin-mp (n = 5) and Histidine-Tryptophan-Ketoglutarate solution (n = 5). ResultsA selection of 8 genes was made based on micro-array results: Tumor necrosis factor receptor superfamily member 10-A like, Regulator of G-protein signaling 2, Nuclear factor kappa beta inhibitor zeta, Interleukin-1 beta, Fibroblast growth factor 6 and DNA damage-inducible transcript 4, Hypoxia-inducible factor 1-alpha and Caspase-3. The muscle flap replantation experiment compared their expression patterns before and after preservation and replantation and showed overall comparable gene expression between the preservation groups. ConclusionsThe expression of genes related to ischemia, apoptosis and inflammation was comparable between the ex-vivo perfusion and static cold storage groups. These results suggest that ex-vivo perfusion might be a promising technique for 18 hour muscle preservation in terms of decreasing ischemia-reperfusion injury.

Ex Situ Heart Perfusion Improves Preservation of Endothelial Function in Both DBD and DCD Hearts

Purpose Ex situ heart perfusion (ESHP) decreases ischemic time and improves myocardial preservation for transplantation. However, the effects of machine perfusion on endothelial function has not yet been determined. We aimed to compare coronary vasomotor function and endothelial activation following transplantation between hearts donated after circulatory death (DCD) and controls (beating-heart donations) preserved in cold storage or ESHP Methods DCD pigs underwent hypoxic circulatory arrest via asphyxiation followed by 15min of warm ischemia . Both DCD and control hearts were preserved with either 3h of cold storage or 4h of ESHP. Following transplantation, both groups were reperfused for 3h. We assessed coronary artery segments for endothelial-dependent (Edep) and -independent (Eind) relaxation, and sensitivity to vasospasm using a small vessel myograph. Expression of VCAM-1 , and endothelin receptors A (ETa) and B (ETb) were measured with immunoblotting Results Preservation with ESHP partially improved Edep (p=0.098) and significantly enhanced Eind (p=0.004) in controls. DCD hearts showed no differences in Edep (p=0.266), Eind (p=0.182) compared to controls when preserved in cold storage. Preservation of DCD hearts using ESHP significantly improved Edep (p Conclusion ESHP strategies have enabled DCD heart transplantation and expansion of the donor heart pool. Limiting cold ischemia by machine perfusion with a normothermic, oxygenated, and blood-based perfusate seems to limit endothelial activation and dysfunction by decreasing ischemia-reperfusion injury . This may lead to a reduced rate of early graft dysfunction and late development of allograft vasculopathy

The Role of Adipokines in Surgical Procedures Requiring Both Liver Regeneration and Vascular Occlusion.

Liver regeneration is a perfectly calibrated mechanism crucial to increase mass recovery of small size grafts from living donor liver transplantation, as well as in other surgical procedures including hepatic resections and liver transplantation from cadaveric donors. Regeneration involves multiple events and pathways in which several adipokines contribute to their orchestration and drive hepatocytes to proliferate. In addition, ischemia-reperfusion injury is a critical factor in hepatic resection and liver transplantation associated with liver failure or graft dysfunction post-surgery. This review aims to summarize the existing knowledge in the role of adipokines in surgical procedures requiring both liver regeneration and vascular occlusion, which increases ischemia-reperfusion injury and regenerative failure. We expose and discuss results in small-for-size liver transplantation and hepatic resections from animal studies focused on the modulation of the main adipokines associated with liver diseases and/or regeneration published in the last five years and analyze future perspectives and their applicability as potential targets to decrease ischemia-reperfusion injury and improve regeneration highlighting marginal states such as steatosis. In our view, adipokines means a promising approach to translate to the bedside to improve the recovery of patients subjected to partial hepatectomy and to increase the availability of organs for transplantation.

New Amino-steroid-anthracenone with Biological Activity Against Ischemia-reperfusion Injury in a Wistar Rat Model

Objective:The main objective of this study was to evaluate the biological activity of an ASA (Amino-Steroid-Anthracenone derivative) against heart failure caused by the ischemia- reperfusion injury (translated as infarct area).Methods:Biological activity exerted by ASA (0.001-100 nM) on infarct area was determined using an ischemia-reperfusion injury model. In addition, to characterize the molecular mechanism involved in the effect exerted by ASA on left ventricular pressure, some drugs such as estrone (0.001-100 nM), tamoxifen (1 nM), butoxamine (1 nM) and ZM-241385 (1 nM) were used.Results:The experimental data showed that ASA decreased the infarction area significantly (p= 0.05) compared to estrone. Other results indicated that ASA decreased left ventricular pressure and this effect was inhibited by ZM-241385. In addition, ASA increased cAMP levels in a time-dependent manner compared to control conditions.Conclusion:The results showed that ASA decreases ischemia-reperfusion injury (translated as infarct area)viaA2adenosine receptor activation and these phenomena involve changes in cAMP levels.

The effect on early renal function of various dynamic preservation strategies in a preclinical pig ischemia-reperfusion autotransplant model.

The aims of this study were to determine the most optimal timing to start machine perfusion during kidney preservation to improve early graft function and to evaluate the impact of temperature and oxygen supply during machine perfusion in a porcine ischemia-reperfusion autotransplant model. The left kidney of an approximately 40-kg female Belgian Landrace pig was exposed to 30 minutes of warm ischemia via vascular clamping and randomized to 1 of 6 study groups: (1) 22-hour static cold storage (SCS) (n = 6), (2) 22-hour hypothermic machine perfusion (HMP) (n = 6), (3) 22-hour oxygenated HMP (n = 7), (4) 20-hour HMP plus 2-hour normothermic perfusion (NP) (n = 6), (5) 20-hour SCS plus 2-hour oxygenated HMP (n = 7), and (6) 20-hour SCS plus 2-hour NP (n = 6). Graft recovery measured by serum creatinine level was significantly faster for continuous HMP preservation strategies compared with SCS alone and for all end-ischemic strategies. The active oxygenated 22-hour HMP group demonstrated a significantly faster recovery from early graft function compared with the 22-hour nonactive oxygenated HMP group. Active oxygenation was also found to be an important modulator of a faster increase in renal flow during HMP preservation. Continuous oxygenated HMP applied from the time of kidney procurement until transplant might be the best preservation strategy to improve early graft function.