Furosemide attenuates tubulointerstitial injury and allows functional testing of porcine kidneys during normothermic machine perfusion.

BACKGROUND: Normothermic machine perfusion (NMP) is a promising pretransplant kidney quality assessment platform, but it remains crucial to increase its diagnostic potential while ensuring minimal additional injury to the already damaged kidney. Interventions that alter tubular transport can influence renal function and injury during perfusion. This study aimed to determine whether furosemide and desmopressin affect renal function and injury during NMP. METHODS: Eighteen porcine kidneys (n = 6 per group) were subjected to 30 min of warm ischemia and 4 h of oxygenated hypothermic perfusion before being subjected to 6 h of NMP. Each organ was randomized to receive no drug, furosemide (750 mg), or desmopressin (16 µg) during NMP. RESULTS: Compared with the other groups, the addition of furosemide resulted in significantly increased urine output, fractional excretion of sodium and potassium, and urea clearance during NMP. Urinary neutrophil gelatinase-associated lipocalin levels decreased significantly with furosemide supplementation compared with the other groups. The addition of desmopressin did not result in any significantly different outcome measurements compared with the control group. CONCLUSIONS: This study showed that the addition of furosemide affected renal function while attenuating tubulointerstitial injury during NMP. Therefore, furosemide supplementation may provide renal protection and serve as a functional test for pretransplant kidney viability assessment during NMP.

Off-clamp Versus On-clamp Partial Nephrectomy: Re-envision of a Dilemma.

We contextualize controversial evidence on the impact of warm ischemia on functional outcomes after partial nephrectomy for localized renal tumors and provide a holistic framework for re-envisioning the dilemma of off-clamp versus on-clamp surgery. The focus should shift away from the surgeon towards patient- and kidney-related characteristics.

The impact on the bioenergetic status and oxidative-mediated tissue injury of a combined protocol of hypothermic and normothermic machine perfusion using an acellular haemoglobin-based oxygen carrier: The cold-to-warm machine perfusion of the liver.

INTRODUCTION: The combination of hypothermic and normothermic machine perfusion (HMP+NMP) of the liver provides individual benefits of both techniques, improving the rescue of marginal organs. The aim of this study was to investigate the effect on the bioenergetic status and the oxidative-mediated tissue injury of an uninterrupted combined protocol of HMP+NMP using a single haemoglobin-based oxygen carrier (HBOC)-based perfusate. METHODS: Ten discarded human donor livers had either 2 hours of dual hypothermic oxygenated perfusion (D-HOPE) with sequential controlled rewarming (COR) and then NMP using the HBOC-based perfusate uninterruptedly (cold-to-warm group); or 2 hours of hypothermic oxygenated perfusion (HOPE) with an oxygen carrier-free perfusate, followed by perfusate exchange and then NMP with an HBOC-based perfusate. Markers of liver function, tissue adenosine triphosphate (ATP) levels and tissue injury were systematically assessed. RESULTS: The hypothermic phase downregulated mitochondrial respiration and increased ATP levels in both groups. The cold-to-warm group presented higher arterial vascular resistance during rewarming/NMP (p = 0.03) with a trend of lower arterial flow (p = 0.09). At the end of NMP tissue expression of markers of reactive oxygen species production, oxidative injury and inflammation were comparable between the groups. CONCLUSION: The uninterrupted combined protocol of HMP+NMP using an HBOC-based perfusate-cold-to-warm MP-mitigated the oxidative-mediated tissue injury and enhanced hepatic energy stores, similarly to an interrupted combined protocol; however, it simplified the logistics of this combination and may favour its clinical applicability.

Human Atrial Natriuretic Peptide in Cold Storage of Donation After Circulatory Death Rat Livers: An Old but New Agent for Protecting Vascular Endothelia?

BACKGROUND: Current critical shortage of donor organs has increased the use of donation after circulatory death (DCD) livers for transplantation, despite higher risk for primary nonfunction or ischemic cholangiopathy. Human atrial natriuretic peptide (hANP) is a cardiovascular hormone that possesses protective action to vascular endothelia. We aimed to clarify the therapeutic potential of hANP in cold storage of DCD livers. METHODS: Male Wistar rats were exposed to 30-minute warm ischemia in situ. Livers were then retrieved and cold-preserved for 6 hours with or without hANP supplementation. Functional and morphological integrity of the livers was evaluated by oxygenated ex vivo reperfusion at 37°C. RESULTS: hANP supplementation resulted in significant reduction of portal venous pressure (12.2 ± 0.5 versus 22.5 ± 3.5 mm Hg, P < 0.001). As underlying mechanisms, hANP supplementation significantly increased tissue adenosine concentration (P = 0.008), resulting in significant upregulation of endothelial nitric oxide synthase and significant downregulation of endothelin-1 (P = 0.01 and P = 0.004 vs. the controls, respectively). Consequently, hANP significantly decreased transaminase release (P < 0.001) and increased bile production (96.2 ± 18.2 versus 36.2 ± 15.2 µL/g-liver/h, P < 0.001). Morphologically, hepatocytes and sinusoidal endothelia were both better maintained by hANP (P = 0.021). Electron microscopy also revealed that sinusoidal ultrastructures and microvilli formation in bile canaliculi were both better preserved by hANP supplementation. Silver staining also demonstrated that hANP significantly preserved reticulin fibers in Disse space (P = 0.017), representing significant protection of sinusoidal frameworks/architectures. CONCLUSIONS: Supplementation of hANP during cold storage significantly attenuated cold ischemia/warm reperfusion injury of DCD livers.

Targeting Phosphodiesterase-5 by Vardenafil Improves Vascular Graft Function.

OBJECTIVES: Ischaemia reperfusion (IR) injury occurs during vascular graft harvesting and implantation during vascular/cardiac surgery. Elevated intracellular cyclic guanosine monophosphate (cGMP) levels contribute to an effective endothelial protection in different pathophysiological conditions. The hypothesis that the phosphodiesterase-5 inhibitor vardenafil would protect vascular grafts against IR injury by upregulating the nitric oxide-cGMP pathway in the vessel wall of the bypass graft was investigated. METHODS: Lewis rats (n = 6-7/group) were divided into Group 1, control; Group 2, donor rats received intravenous saline; Group 3, received intravenous vardenafil (30 µg/kg) 2 h before explantation. Whereas aortic arches of Group 1 were immediately mounted in an organ bath, aortic segments of Groups 2 and 3 were stored for 2 h in saline and transplanted into the abdominal aorta of the recipient. Two hours after transplantation, the implanted grafts were harvested. Endothelium dependent and independent vasorelaxations were investigated. TUNEL, CD-31, ICAM-1, VCAM-1, α-SMA, nitrotyrosine, dihydroethidium and cGMP immunochemistry were also performed. RESULTS: Compared with the control, the saline group showed significantly attenuated endothelium dependent maximal relaxation (Rmax) 2 h after reperfusion, which was significantly improved by vardenafil supplementation (Rmax control, 91 ± 2%; saline 22 ± 2% vs. vardenafil 39 ± 4%, p < .001). Vardenafil pre-treatment significantly reduced DNA fragmentation (control 9 ± 1%, saline 66 ± 8% vs. vardenafil 13 ± 1%, p < .001), nitro-oxidative stress (control 0.8 ± 0.3, saline 7.6 ± 1.3 vs. vardenafil 3.8 ± 1, p = .036), reactive oxygen species level (vardenafil 36 ± 4, control 34 ± 2 vs. saline 43 ± 2, p = .049), prevented vascular smooth muscle cell damage (control 8.5 ± 0.7, saline 4.3 ± 0.6 vs. vardenafil 6.7 ± 0.6, p = .013), decreased ICAM-1 (control 4.1 ± 0.5, saline 7.0 ± 0.9 vs. vardenafil 4.4 ± 0.6, p = .031), and VCAM-1 score (control 4.4 ± 0.4, saline 7.3 ± 1.0 vs. vardenafil 5.2 ± 0.4, p = .046) and increased cGMP score in the aortic wall (control 11.2 ± 0.8, saline 6.5 ± 0.8 vs. vardenafil 8.9 ± 0.6, p = .016). The marker for endothelial integrity (CD-31) was also higher in the vardenafil group (control 74 ± 4%, saline 22 ± 2% vs. vardenafil 40 ± 3%, p = .008). CONCLUSIONS: The results support the view that impairment of intracellular cGMP signalling plays a role in the pathogenesis of the endothelial dysfunction of an arterial graft after bypass surgery, which can effectively be prevented by vardenafil. Its clinical use as preconditioning drug could be a novel approach in vascular/cardiac surgery.

Addition of Berberine to Preservation Solution in an Animal Model of Ex Vivo Liver Transplant Preserves Mitochondrial Function and Bioenergetics from the Damage Induced by Ischemia/Reperfusion.

Liver transplantation is a therapeutic regimen to treat patients with non-malignant end-stage liver diseases and malignant tumors of hepatic origin. The ischemia/reperfusion (I/R) injury in liver transplantation is associated with disruption of mitochondrial function in the hepatic parenchyma. Several studies have been conducted in animal models to identify pharmacological therapeutic strategies to minimize the injury induced by the cold/warm I/R in liver transplantation. Most of these studies were conducted in unrealistic conditions without the potential to be translated to clinical usage. Berberine (BBR) is a pharmacological compound with a potential protective effect of the mitochondrial function in the context of I/R. For the future clinical application of these pharmacological strategies, it is essential that a close resemblance exists between the methodology used in the animals models and real life. In this study, we have demonstrated that the addition of BBR to the preservation solution in an I/R setting preserves mitochondrial function and bioenergetics, protecting the liver from the deleterious effects caused by I/R. As such, BBR has the potential to be used as a pharmacological therapeutic strategy.

Bronchodilator Inhalation During Ex Vivo Lung Perfusion Improves Posttransplant Graft Function After Warm Ischemia.

BACKGROUND: We hypothesized that an injured lung graft from donation after cardiac death donors could be reconditioned before transplantation using an ex vivo lung perfusion (EVLP) system and ventilation with high-dose short-acting ß2-adrenergic receptor agonists. METHODS: Cardiac arrest was induced in a canine model by intravenous potassium chloride injection. Lungs were randomly assigned to two groups after 150 minutes of warm ischemia: inhalation of 1,400 µg of procaterol (BETA group, n = 5) or control group receiving solvent (CON group, n = 5) during EVLP. Left lungs were transplanted after 120 minutes of EVLP. Functional variables, tissue adenosine 5'-triphosphate levels, and tissue cyclic adenosine monophosphate levels were measured 240 minutes after transplantation. RESULTS: Physiologic pulmonary function was similar at the end of EVLP in both groups. However, significantly better graft oxygenation, dynamic pulmonary compliance, and reduced pulmonary vascular resistance were observed in the BETA group than in the CON group 240 minutes after transplantation. No severe adverse effects were observed after lung transplantation in the BETA group. Lung tissue adenosine 5'-triphosphate levels and cyclic adenosine monophosphate levels were significantly higher in the BETA group than in the CON group at the end of EVLP and at 240 minutes after transplantation. CONCLUSIONS: High-dose nebulized procaterol during EVLP ameliorated lung graft dysfunction at the early posttransplantation period without severe adverse effects. These data suggest that lung reconditioning with procaterol ventilation during EVLP improves lung graft function after transplantation.

Effects of warm ischemia and reperfusion on the liver microcirculatory phenotype of rats: underlying mechanisms and pharmacological therapy.

Warm ischemia and reperfusion (WIR) causes hepatic damage and may lead to liver failure, however the mechanisms involved are largely unknown. Here we have characterized the microcirculatory status and endothelial phenotype of livers undergoing WIR, and evaluated the use of simvastatin in WIR injury prevention. Male Wistar rats received simvastatin, or vehicle, 30 min before undergoing 60 min of partial warm ischemia (70%) followed by 2 h or 24 h of reperfusion. Hepatic and systemic hemodynamics, liver injury (AST, ALT, LDH), endothelial function (vasodilatation in response to acetylcholine), KLF2 and nitric oxide pathways, oxidative stress, inflammation (neutrophil and macrophage infiltration) and cell death were evaluated. Profound microcirculatory dysfunction occurred rapidly following WIR. This was evidenced by down-regulation of the KLF2 vasoprotective pathway, impaired vasodilatory capability and endothelial activation, altogether leading to increased hepatic vascular resistance and liver inflammation, with significant leukocyte infiltration, oxidative stress and cell death. Simvastatin preserved the hepatic endothelial phenotype, and blunted the detrimental effects of WIR on liver hemodynamics and organ integrity. In conclusion, WIR-induced injury to liver sinusoidal endothelial cells is mitigated by pre-treatment with Simvastatin probably through a KLF2-dependent mechanism.

Short-term Outcomes of Intraoperative Cell Saver Transfusion During Open Partial Nephrectomy.

OBJECTIVE: To determine whether transfusion using the Cell Saver system is associated with inferior outcomes in patients undergoing open partial nephrectomy. METHODS: All patients who underwent open partial nephrectomy by a single surgeon (BJD) from August 2008 to April 2015 were retrospectively identified. Operations were grouped and compared according to whether they included a transfusion using the Cell Saver intraoperative cell salvage system. RESULTS: Sixty-nine open partial nephrectomies in 67 patients were identified. Thirty-three procedures (48%) included a Cell Saver transfusion. Most tumors were clear cell renal cell carcinoma (62%) and stage T1a (68%). There were no significant differences between groups for any measured clinical or pathologic characteristics. Operations including a Cell Saver transfusion were longer (141 vs 108 minutes, P <.001), had significantly greater blood loss (600 vs 200 mL, P <.001), and had longer median renal ischemia times (15 vs 10 minutes, P = .03). There were no significant differences in postoperative complication rate (21% vs 17%, P = .83) or median length of hospital stay (3 vs 3 days, P = .09). At a median follow-up of 23 months (interquartile range: 8-42 months), 1 patient in the non-Cell Saver transfusion group had cancer recurrence. There was no metastatic progression or cancer-specific mortality in either group. CONCLUSION: Cell Saver transfusion during open partial nephrectomy was not associated with inferior outcomes with short-term follow-up, and no patients developed metastatic disease.

The effect of a hydrogen sulfide releasing molecule (Na2S) on the cold storage of livers from cardiac dead donor rats. A study in an ex vivo model.

Liver transplantation is currently the preferred treatment option for end-stage liver disease. Donation after cardiac death was a common practice in the early years of organ donation before brain death criteria were established. Those organs were subjected to variable periods of warm ischemia that might intensify cold ischemia/reperfusion injuries. In the present, shortage of brain dead donors has led to the reassessment of organ donation after cardiac death. Since many cytoprotective roles have been describe for H2S during ischemia/reperfusion on a variety of tissues, we hypothesized that graft exposure to this bioactive gas might improve preservation of non-heart beating donated organs. Therefore, to establish a rat model of donation post-cardiac arrest and using this approach to judge H2S delivery effects on graft hypothermic preservation, were the main objectives of this investigation. Cardiopulmonary arrest was induced in sedated rats by overload of potassium (K(+)). Livers were surgically removed and subsequently stored in HTK Solution (Histidine-tryptophan-ketoglutarate) at 0-4°C. After 24 h of hypothermic preservation, livers were rewarmed in an ex vivo model. Three experimental groups were established as follows: I--Livers procured before cardiac death and cold stored 24 h in HTK (BCD); II--Livers procured after cardiac death (45 min) and cold stored 24 h in HTK (ACD); III--Livers procured after cardiac death (45 min) and cold stored 24 h in HTK+10 µM Sodium Sulfide (Na2S) (ACD-SS). Data suggest that after 45 min of warm ischemia, viability parameters assessed during reperfusion in the ex vivo model were significantly impaired. Real time PCR revealed that after ex vivo reperfusion there is an increased expression of HO-1 and TNF-α and a modest drop in Bcl-2 mRNA, which could be interpreted as the cellular response to the hypoxic insult sustained during warm ischemia. On the other hand, warm ischemic livers exposed to H2S during cold storage, improved microcirculation, morphology and viability parameters during ex vivo reperfusion and showed significant modulation of HO-1 mRNA expression. In conclusion, HTK supplementation with Na2S arose as a potential treatment to recover non-heart beating harvested organs. Furthermore, an appropriate model of cardiac dead liver donors was successfully developed.

Protective effects of Hammada scoparia flavonoid-enriched fraction on liver injury induced by warm ischemia/reperfusion.

CONTEXT: Hepatic ischemia/reperfusion injury (IRI) is a major cause of liver damage during liver surgery and transplantation. Plants have historically been used in treating liver damage, and Hammada scoparia (Pomel) (Chenopodiaceae) has been reported to possess a broad spectrum of pharmacological and therapeutic activities. OBJECTIVE: In this study, a flavonoid-enriched fraction was used before the warm ischemia (WI) process as pharmacological preconditioning and in combination with technical postconditioning to evaluate their protective effects. MATERIALS AND METHODS: The rats were divided into five groups: a sham group; a control group (Control-IR) that was submitted to 60 min WI; a Pharmacological Preconditioning group (PreC-IR) that received flavonoid-enriched fraction (200 mg/kg body weight); a Postconditioning group (PostC) and a PreC + PostC group. RESULTS: The use of the flavonoid-enriched fraction was noted to significantly (p < 0.05) reduce liver injury, as evidenced by the decrease in liver transaminase activities (AST and ALT) and lactic dehydrogenase (LDH), alkaline phosphatase (ALP), and lipid peroxidation (TBARS), levels as well as the enhancement of antioxidant enzymes (catalase (CAT), superoxide dismutase (SOD), and glutathione peroxidase (GPx)) responses. The results also indicated that, compared with the separate application of pharmacological preconditioning and postconditioning, the combination of both treatments was more effective in reducing tissue oxidative stress levels through modulating SOD, GSH-PX, and CAT activities. Furthermore, the combined protocol further decreased the liver morphological score compared with solo treatment. DISCUSSION AND CONCLUSION: Overall, the results indicate that the H. scoparia flavonoid-enriched fraction could be a promising candidate for future application as a pharmacological preconditioning agent against hepatic IRI.

Improving mitochondrial bioenergetics under ischemic conditions increases warm ischemia tolerance in the kidney.

Ischemia time during partial nephrectomy is strongly associated with acute and chronic renal injury. ATP depletion during warm ischemia inhibits ATP-dependent processes, resulting in cell swelling, cytoskeletal breakdown, and cell death. The duration of ischemia tolerated by the kidney depends on the amount of ATP that can be produced with residual substrates and oxygen in the tissue to sustain cell function. We previously reported that the rat can tolerate 30-min ischemia quite well but 45-min ischemia results in acute kidney injury and progressive interstitial fibrosis. Here, we report that pretreatment with SS-20 30 min before warm ischemia in the rat increased ischemia tolerance from 30 to 45 min. Histological examination of kidney tissues revealed that SS-20 reduced cytoskeletal breakdown and cell swelling after 45-min ischemia. Electron microscopy showed that SS-20 reduced mitochondrial matrix swelling and preserved cristae membranes, suggesting that SS-20 enhanced mitochondrial ATP synthesis under ischemic conditions. Studies with isolated kidney mitochondria showed dramatic reduction in state 3 respiration and respiratory control ratio after 45-min ischemia, and this was significantly improved by SS-20 treatment. These results suggest that SS-20 increases efficiency of the electron transport chain and improves coupling of oxidative phosphorylation. SS-20 treatment after ischemia also significantly reduced interstitial fibrosis. These new findings reveal that enhancing mitochondrial bioenergetics may be an important target for improving ischemia tolerance, and SS-20 may serve well for minimizing acute kidney injury and chronic kidney disease following surgical procedures such as partial nephrectomy and transplantation.

Ginsenoside Rg1 protects mouse liver against ischemia-reperfusion injury through anti-inflammatory and anti-apoptosis properties.

BACKGROUND: Ginsenoside Rg1, the major effective component of ginseng, possesses a variety of pharmacologic activities. The objective of this study was to investigate the effects of Rg1 on liver ischemia-reperfusion (IR) injury and explore its potential mechanisms. MATERIALS AND METHODS: Liver warm IR injury was achieved by occluding the portal vein and hepatic artery for 1 h followed by 6-h reperfusion. Eighteen mice were equally randomized into three groups: sham group, IR group, and IR plus Rg1 group (n = 6 mice per group). Mice received an intravenous dose of 20 mg/kg Rg1 or an equivalent volume of saline before ischemic insult. Liver samples and serum were collected for analyses. Serum aminotransferase, histopathology, and apoptosis were determined. Cytokines were measured by real-time quantitative reverse transcription polymerase chain reaction (qRT-PCR). The phosphorylation of nuclear factor kappa B (NF-κB) p65 was assessed by Western blotting. In addition, the effect of Rg1 in a simulated IR model in vitro was also investigated. Rg1 (100 ug/mL and 500 ug/mL) was administered 1 h before hypoxia insult, and then apoptosis was measured after 12-h reperfusion. RESULTS: Liver IR injury led to a dramatic increase in aminopherase activity, apoptosis and necrosis of hepatocytes, and production of proinflammatory cytokines. Pretreatment with Rg1 protected mice from IR-induced liver injury. Treatment with a high-dose Rg1 (500 ug/mL) significantly suppressed apoptosis compared with a lower dose or control (both P < 0.001). Phosphorylation of NF-κB p65 was increased significantly in IR group, and administration with Rg1 suppressed the level of phosphorylation. CONCLUSIONS: Pretreatment of mice with Rg1 reduced hepatocellular apoptosis and inhibited inflammatory response, which was in part through the NF-κB signaling pathway. Rg1 may provide a novel therapeutic strategy for the treatment of IR-induced liver injury.

Can right-sided hand-assisted retroperitoneoscopic donor nephrectomy be advocated above standard laparoscopic donor nephrectomy: a randomized pilot study.

Endoscopic techniques have contributed to early recovery and increased quality of life (QOL) of live kidney donors. However, laparoscopic donor nephrectomy (LDN) may have its limitations, and hand-assisted retroperitoneoscopic donor nephrectomy (HARP) has been introduced, mainly as a potentially safer alternative. In a randomized fashion, we explored the feasibility and potential benefits of HARP for right-sided donor nephrectomy in a referral center with longstanding expertise on the standard laparoscopic approach. Forty donors were randomly assigned to either LDN or HARP. Primary outcome was operating time, and secondary outcomes included QOL, complications, pain, morphine requirement, blood loss, warm ischemia time, and hospital stay. Follow-up time was 1 year. Skin-to-skin time did not significantly differ between both groups (162 vs. 158 min, P = 0.98). As compared to LDN, HARP resulted in a shorter warm ischemia time (2.8 vs. 3.9 min, P < 0.001) and increased blood loss (187 vs. 50 ml, P < 0.001). QOL, complication rate, pain, or hospital stay was not significantly different between the groups. Right-sided HARP is feasible but does not confer clear benefits over standard right-sided LDN yet. Further studies should explore the value of HARP in difficult cases such as the obese donor and the value of HARP for transplantation centers starting a live kidney donation program (Dutch Trial Register number: NTR3096). Nevertheless, HARP is a valuable addition to the surgical armamentarium in live donor surgery.

Results in laparoscopic living donor nephrectomy: a multicentric experience.

OBJECTIVE: Renal transplantation is the most successful therapy to improve survival and quality of life for patients with end-stage renal disease. Living donors have been used as an alternative to reduce the stay on the waiting list. Laparoscopic living donor nephrectomy has become the standard procedure for renal transplantation. Minimally invasive surgery involves less postoperative pain with less analgesic requirements allowing shorter hospital stay for the donor. MATERIAL AND METHODS: We retrospectively analyzed demographic and intraoperative data and surgical complications for 46 patients who underwent laparoscopic living donor nephrectomy between March 2001 and March 2011. RESULTS: Mean donor age was 41 years. Mean operative time was 170 ± 45 minutes. The average cold ischemic time was 40 minutes and warm ischemic time was 26 minutes. Twenty-one patients were donors for pediatric receptors. Fourty patients underwent left laparoscopic nephrectomy, the other 6 patients underwent right laparoscopic nephrectomy due to vascular anatomic variant. Right laparoscopic nephrectomy was converted in 1 case (2.2%) due to renal vein laceration without donor morbidity and without compromise of graft function. Renal function at the second day post donor nephrectomy was measured using serum creatinine averaged 1.2 mg/dL with a mean increase of 0.4 mg/dL from baseline, with normalization after 30 days. No patient required blood transfusion, and there were no immediate surgical complications, infections, or mortality. One patient developed an incisional hernia in relation to the site of kidney removal. The mean hospital stay was 5 ± 1 days. CONCLUSIONS: Laparoscopic nephrectomy in our experience is a safe technique without postoperative morbidity or mortality. It is associated with low levels of pain, early discharge and early return to physical activity and work, good sense of aesthetic results, and long-term graft function comparable to traditional nephrectomy and cadaveric grafts.

Dietary omega-3 polyunsaturated fatty acids attenuate hepatic ischemia/reperfusion injury in rats by modulating toll-like receptor recruitment into lipid rafts.

BACKGROUND & AIMS: Hepatic ischemia/reperfusion (I/R) injury may activate innate immunity through the interaction of toll-like receptor 4 (TLR4) with endogenous ligands. Omega-3 polyunsaturated fatty acids (ω-3 PUFAs) exert suppressive effects on innate immunity through various mechanisms. In this study, we investigated the effect of dietary supplementation with ω-3 PUFAs on hepatic I/R in rats. METHODS: Three groups of Wistar male rats were fed a standard diet with water, and fish oil as ω-3 PUFAs, or soybean oil as ω-6 PUFAs for 7 days. Subsequently, the rats underwent normothermic, 60 min, partial liver ischemia followed by 6 h of reperfusion. The activation of TLR4 signaling was evaluated using membrane lipid raft isolation. After the 6 h of reperfusion, histopathologic alterations, serum ALT levels, TLR4-mediated inflammation were assessed by western blotting and immunohistochemical study. RESULTS: The damage of liver from I/R was diminished by dietary fish oil supplementation. Administration of fish oil inhibited TLR4 receptor recruitment into lipid rafts of cell membrane in liver tissues, which is an initial step required for activation of the downstream signaling pathway. Down-regulation of TLR4-mediated signaling reduced NF-κB activation and consequently, improved I/R injury. CONCLUSIONS: Dietary ω-3 PUFAs supplementation attenuated hepatic I/R injury and could be considered as a nutritional therapeutic aimed at ameliorating I/R injury.

Detrimental effects of prolonged warm renal ischaemia-reperfusion injury are abrogated by supplemental hydrogen sulphide: an analysis using real-time intravital microscopy and polymerase chain reaction.

UNLABELLED: What's known on the subject? and What does the study add? Hydrogen sulphide (H(2) S) has recently been classified as a member of the gasotransmitter family. Its physiological and pathophysiological effects are rapidly expanding with numerous studies highlighting the protective effects of H(2) S on ischaemia-reperfusion injury (IRI) in various organ systems, e.g. heart, liver, CNS and lungs. The mechanisms behind its protective effects reside in its vasodilatory, anti-inflammatory and anti-oxidant characteristics. These specific mechanistic profiles appear to be different across different tissues and models of IRI. We recently showed that supplementation of preservation solutions with H(2) S during periods of prolonged cold renal storage and subsequent renal transplantation leads to a massive and significant survival, functional and tissue protective advantage compared with storage in standard preservation solution alone. However, there have only been a few studies that have evaluated the effects of H(2) S against warm renal IRI; although these studies have focused primarily upon shorter periods of warm renal pedicle clamping, they have shown a clear survival benefit to H(2) S supplementation. The present study adds to the existing literature by evaluating the effects of H(2) S in a model of warm IRI with clinically relevant, prolonged warm ischaemia-reperfusion times (1 h ischaemia, 2 h reperfusion). We show an unprecedented view into real-time renal and hepatic perfusion with intravital microscopy throughout the reperfusion period. We show, for the first time, that supplemental H(2) S has multiple protective functions against the warm IRI-induced tissue damage, which may be clinically applicable to both donation after cardiac death models of renal transplantation, as well as to uro-oncological practices requiring surgical clamping of the renal pedicle, e.g. during a partial nephrectomy. OBJECTIVE: • To determine the protective role of supplemental hydrogen sulphide (H(2) S) in prolonged warm renal ischaemia-reperfusion injury (IRI) using real-time intravital microscopy (IVM). MATERIALS AND METHODS: • Uninephrectomised Lewis rats underwent 1 h of warm ischaemia and 2 h of reperfusion during intraperitoneal treatment with phosphate buffer saline (IRI, n = 10) or 150 µmol/L NaHS (IRI+H(2) S, n = 12) and were compared with sham-operated rats (n = 9). • Blood was collected for measurement of serum creatinine (Cr), alanine aminotransferase (ALT) and aspartate aminotransferase (AST). • IVM was performed to assess renal and hepatic microcirculation. • Kidneys were sectioned for histology and real-time quantitative polymerase chain reaction for markers of inflammation. RESULTS: • The mean (sd) Cr concentration raised to 72.8(2.5) µmol/L after IRI from 11.0 (0.7) µmol/L (sham) but was partially inhibited with H(2) S to 62.8 (0.9) µmol/L (P < 0.05). • H(2) S supplementation during IRI increased renal capillary perfusion on IVM, and improved acute tubular necrosis and apoptotic scores on histology (P < 0.05). • Supplemental H(2) S decreased expression of the pro-inflammatory markers toll-like receptor 4, tumour necrosis factor α, interleukin 8, C-C chemokine receptor type 5, interferon γ and interleukin 2 (P < 0.05). • Distant organ (liver) dysfunction after renal IRI was limited with H(2) S supplementation: blunting of the ALT and AST surge, decreased hepatic sinusoidal vasodilation, and decreased leukocyte infiltration in post-sinusoidal venules (P < 0.05). • H(2) S supplementation directly inhibited interleukin 8-induced neutrophil chemotaxis in vitro (P < 0.05). CONCLUSIONS: • These findings are the first to show the real-time protective role of supplemental H(2) S in prolonged periods of warm renal IRI, perhaps acting by decreasing leukocyte migration and limiting inflammatory responses. • The protective effects of H(2) S suggest potential clinical applications in both donors after cardiac death models of renal transplantation and oncological practices requiring vascular clamping.

Impact of venous systemic oxygen persufflation supplemented with nitric oxide gas on cold-stored, warm ischemia-damaged experimental liver grafts.

The increasing shortage of donor organs has led to the increasing use of organs from non-heart-beating donors. We aimed to assess the impact of venous systemic oxygen persufflation (VSOP) supplemented with nitric oxide (NO) gas during the cold storage (CS) of warm ischemia (WI)-damaged experimental liver grafts. Rat livers (n = 5 per group) were retrieved after 30 minutes of WI induced by cardiac arrest (the WI group) and were thereafter preserved for 24 hours by CS in histidine tryptophan ketoglutarate solution. During CS, gaseous oxygen was insufflated via the caval vein with 40 ppm NO (the VSOP-NO group) or without NO (the VSOP group). Cold-stored livers without WI served as controls. Liver viability was assessed after the preservation period by normothermic isolated reperfusion for 45 minutes with oxygenated Krebs-Henseleit buffer. After 45 minutes of reperfusion, the VSOP-NO-treated livers showed significantly lower alanine aminotransferase values than the WI-damaged livers (10.2 ± 0.2 versus 78.2 ± 14.6 IU/L), whereas the control livers showed no differences from the VSOP-NO-treated livers. The mitochondrial enzyme release was lower in the VSOP-NO group (4.0 ± 0.7 IU/L) versus the WI group (18.2 ± 4.9 IU/L). An increased portal vein pressure was observed throughout reperfusion (45 minutes) in the WI group (21.7 ± 0.2 mm Hg) versus the VSOP-NO group (12.2 ± 0.8 mm Hg) and the control group (19.9 ± 0.4 mm Hg). Furthermore, the NO concentration in the perfusate after 5 minutes of reperfusion was highest in the VSOP-NO group. The release of malondialdehyde into the perfusate was significantly reduced in the VSOP-NO group (0.9 ± 0.1 nmol/mL) versus the WI group (31.3 ± 5.3 nmol/mL). In conclusion, the resuscitation of livers after 30 minutes of WI to a level comparable to that of nonischemically damaged livers is possible with VSOP supplemented with NO gas. Moreover, the application of VSOP with NO minimizes the extent of injuries caused by oxygen free radicals during preservation.

Green tea extract ameliorates reperfusion injury to rat livers after warm ischemia in a dose-dependent manner.

SCOPE: Polyphenolic constituents of green tea (Camellia sinensis) have been shown to be potent scavengers of reactive oxygen species (ROS). Thus, this study was designed to assess its effects after liver ischemia-reperfusion. METHODS AND RESULTS: Fasted Sprague-Dawley rats were gavaged with different concentrations of green tea extract (GTE) 2 h before 90 min of warm ischemia of the left lateral liver lobe (30% of liver). Controls were given the same volume of Ringer's solution. A preparation of pentobarbital sodium (intraperitoneal) and ketamine (intramuscular) was used for anesthesia. After reperfusion, transaminases, liver histology, hepatic microcirculation, and both phagocytosis of latex bead particles as well as the expression of tumor necrosis alpha (TNF-α) to index cellular activation were investigated. Furthermore, the expression of superoxide dismutase (Mn-SOD) was assessed. After 90 min of warm ischemia aminotransferase (AST), alanine aminotransferase (ALT), and lactate dehydrogenase (LDH) increased dramatically to 1946 ± 272/3244 ± 757 U/L, 1680 ± 134/2080 ± 379 U/L, and 7857 ± 1851/2036 ± 1193 U/L at 2/6 h, respectively. GTE (200 mg/kgbody weight) significantly prevented this increase in a dose-dependent manner by 21-51% at 2 h and 29-34% at 6 h, respectively. Histology confirmed the protective effects while both TNF-α expression and phagocytosis of latex beads by Kupffer cells (KCs) were significantly reduced. GTE intake significantly increased the expression of manganese superoxide dismutase. In vivo microscopy revealed improved acinar and sinusoidal perfusion after GTE. CONCLUSION: Preconditioning with a single oral dose of GTE ameliorates ischemia-reperfusion injury in liver. Decreased cellular activation and improved microcirculation are the proposed mechanisms.

Impact of normothermic perfusion and protein supplementation on human endothelial cell function during organ preservation.

BACKGROUND: Hypothermia-induced changes in endothelial cell (EC) morphology and function after organ storage may influence the initial outcome and development of transplant-associated coronary artery disease. METHODS: Human saphenous vein ECs were incubated with saline (NaCl), University of Wisconsin (UW), and histidine-tryptophan-ketoglutarate (HTK) solution, with and without protein additives, at 4 degrees C and 37 degrees C. After 6 hours, ECs were recultivated for 24 and 48 hours with culture medium (reperfusion). Mitochondrial activity, adenosine triphosphate concentration, cell count, and inflammatory responses were analyzed. RESULTS: Cold preservation did not affect the mitochondrial activity of ECs and allowed a complete regeneration of the metabolic turnover after reperfusion. However, under normothermic conditions the metabolism of the cells was influenced by time and type of preservation solution. While both the mitochondrial activity and cell count did not change after treatment with NaCl and culture medium, the metabolic turnover of cells treated with HTK and UW solution significantly increased (twofold) and decreased (twofold, p < 0.05), respectively, after reperfusion. The endothelial reactivity remained unchanged after treatment with NaCl and HTK. The addition of serum proteins significantly improved mitochondrial activity of cells treated with warm NaCl and HTK (p < 0.05). The UW-treated cells burned out through a significant up-regulation of the ATP concentration resulting in a complete metabolic regression after reperfusion and induction of apoptosis. CONCLUSIONS: Normothermic preservation in UW prevented regeneration of ECs, while treatment with HKT solution did not irreversibly affect mitochondrial activity of ECs and allowed complete regeneration of metabolism and function. Serum proteins improved the preservation effect of HTK and NaCl.