Ischemic preconditioning in solid organ transplantation: from experimental to clinics

Nitric Oxide in Cardiac Surgery: A Review Article

Perioperative organ injury remains a medical, social and economic problem in cardiac surgery. Patients with postoperative organ dysfunction have increases in morbidity, length of stay, long-term mortality, treatment costs and rehabilitation time. Currently, there are no pharmaceutical technologies or non-pharmacological interventions that can mitigate the continuum of multiple organ dysfunction and improve the outcomes of cardiac surgery. It is essential to identify agents that trigger or mediate an organ-protective phenotype during cardiac surgery. The authors highlight nitric oxide (NO) ability to act as an agent for perioperative protection of organs and tissues, especially in the heart-kidney axis. NO has been delivered in clinical practice at an acceptable cost, and the side effects of its use are known, predictable, reversible and relatively rare. This review presents basic data, physiological research and literature on the clinical application of NO in cardiac surgery. Results support the use of NO as a safe and promising approach in perioperative patient management. Further clinical research is required to define the role of NO as an adjunct therapy that can improve outcomes in cardiac surgery. Clinicians also have to identify cohorts of responders for perioperative NO therapy and the optimal modes for this technology.

The Sheep as a Large Animal Model for the Investigation and Treatment of Human Disorders

Simple Summary

We review the value of large animal models for improving the translation of biomedical research for human application, focusing primarily on sheep.

Abstract

An essential aim of biomedical research is to translate basic science information obtained from preclinical research using small and large animal models into clinical practice for the benefit of humans. Research on rodent models has enhanced our understanding of complex pathophysiology, thus providing potential translational pathways. However, the success of translating drugs from pre-clinical to clinical therapy has been poor, partly due to the choice of experimental model. The sheep model, in particular, is being increasingly applied to the field of biomedical research and is arguably one of the most influential models of human organ systems. It has provided essential tools and insights into cardiovascular disorder, orthopaedic examination, reproduction, gene therapy, and new insights into neurodegenerative research. Unlike the widely adopted rodent model, the use of the sheep model has an advantage over improving neuroscientific translation, in particular due to its large body size, gyrencephalic brain, long lifespan, more extended gestation period, and similarities in neuroanatomical structures to humans. This review aims to summarise the current status of sheep to model various human diseases and enable researchers to make informed decisions when considering sheep as a human biomedical model.

Understanding Cellular Redox Homeostasis: A Challenge for Precision Medicine

Living organisms use a large repertoire of anabolic and catabolic reactions to maintain their physiological body functions, many of which include oxidation and reduction of substrates. The scientific field of redox biology tries to understand how redox homeostasis is regulated and maintained and which mechanisms are derailed in diverse pathological developments of diseases, where oxidative or reductive stress is an issue. The term “oxidative stress” is defined as an imbalance between the generation of oxidants and the local antioxidative defense. Key mediators of oxidative stress are reactive species derived from oxygen, nitrogen, and sulfur that are signal factors at physiological concentrations but can damage cellular macromolecules when they accumulate. However, therapeutical targeting of oxidative stress in disease has proven more difficult than previously expected. Major reasons for this are the very delicate cellular redox systems that differ in the subcellular compartments with regard to their concentrations and depending on the physiological or pathological status of cells and organelles (i.e., circadian rhythm, cell cycle, metabolic need, disease stadium). As reactive species are used as signaling molecules, non-targeted broad-spectrum antioxidants in many cases will fail their therapeutic aim. Precision medicine is called to remedy the situation.

Impact of cardiopulmonary resuscitation on outcome of kidney transplantations from braindead donors aged ≥65 years

Patients with a history of cardiopulmonary resuscitation (CPR) and subsequent brain death are frequently evaluated for organ donation. Whether kidneys from ≥65-year-old braindead donors with a history of CPR can be transplanted with satisfactory outcomes is unknown. All kidney transplants (KT) from ≥65-year-old donors performed at our centre from 1999 to 2018 (n = 185) were retrospectively analysed and outcome was compared for KTs from donors with and without a history of CPR (n = 27 and n = 158, respectively). No significant differences in the incidence of delayed graft function (DGF) as well as one- and three-year graft function were observed between the CPR and the no-CPR group (DGF: 26.0% vs 31.0%, P = 0.76; one-year serum creatinine: 150.4 μmol/l vs 177.0 μmol/l, P = 0.11; three-year serum creatinine: 150.4 μmol/l vs 168.2 μmol/l, P = 0.52, respectively). Death-censored graft survival was comparable after one and five years (CPR group: 81.5% and 76.7% vs no-CPR group: 86.6% and 75.7%, P = 0.70). Likewise, patient survival was not significantly different. Multivariable Cox regression analysis also did not identify CPR as a significant risk factor for graft loss or death. Our study suggests that, following stringent donor selection, the outcome of KTs from ≥65-year-old braindead donors with and without a history of CPR is comparable. This article is protected by copyright. All rights reserved.

Mitochondria as Therapeutic Targets in Transplantation

Advances in surgical procedures, technology, and immune suppression have transformed organ transplantation. However, the metabolic changes that occur during organ retrieval, storage, and implantation have been relatively neglected since the developments many decades ago of cold storage organ preservation solutions. In this review we discuss how the metabolic changes that occur within the organ during transplantation, particularly those associated with mitochondria, may contribute to the outcome. We show how a better understanding of these processes can lead to changes in surgical practice and the development of new drug classes to improve the function and longevity of transplanted grafts, while increasing the pool of organs available for transplantation.

Renal Procurement: Techniques for Optimizing the Quality of the Graft in the Cadaveric Setting

PURPOSE OF REVIEW

Kidney transplantation is the best treatment for end-stage renal disease. However, due to organ shortage, suboptimal grafts are increasingly being used.

RECENT FINDINGS

We carried out a review on the methods and techniques of organ optimization in the cadaveric setting. Donor care is the first link in a chain of care. Right after brain death, there is a set of changes, of which hormonal and hemodynamic changes are the most relevant. Several studies have been conducted to determine which drugs to administer, although in most cases, the results are not definitive. The main goal seems rather achieve a set of biochemical and hemodynamic objectives. The ischemia-reperfusion injury is a critical factor for kidney damage in transplantation. One of the ways found to deal with this type of injury is preconditioning. Local and remote ischemic preconditioning has been studied for various organs, but studies on the kidney are scarce. A new promising area is pharmacological preconditioning, which is taking its first steps. Main surgical techniques were established in the late twentieth century. Some minor new features have been introduced to deal with anatomical variations or the emergence of donation after circulatory death. Finally, after harvesting, it is necessary to ensure the best conditions for the kidneys until the time of transplantation. Much has evolved since static cold preservation, but the best preservation conditions are yet to be determined. Conservation in the cold has come to be questioned, and great results have appeared at temperatures closer to physiological.

Impact of donor cardiopulmonary resuscitation on the outcome of simultaneous pancreas-kidney transplantation-a retrospective study

Previous cardiac arrest in brain-dead donors has been discussed as a potential risk factor in pancreas transplantation (PT), leading to a higher rate of organ refusal. This study aimed to assess the impact of cardiopulmonary resuscitation (CPR) in brain-dead donors on pancreas transplant outcome. A total of 518 type 1 diabetics underwent primary simultaneous pancreas-kidney (SPK) transplantation at our center between 1994 and 2018. Patients were divided into groups, depending on whether their donor had been resuscitated or not. A total of 91 (17.6%) post-CPR donors had been accepted for transplantation (mean duration of cardiac arrest, 19.4 ± 15.6 min). Those donors were younger (P < 0.001), had lower pancreas donor risk index (PDRI, P = 0.003), and had higher serum creatinine levels (P = 0.021). With a median follow-up of 167 months (IQR 82-229), both groups demonstrated comparable short- and long-term patient and graft survival. The resuscitation time (<20 min vs. ≥20 min) also showed no impact, with similar survival rates for both groups. A multivariable Cox regression analysis suggested no statistically significant association between donor CPR and patient or graft survival. Our results indicate that post-CPR brain-dead donors are suitable for PT without increasing the risk of complications.

Protective effect of nicorandil on collapse‑induced lung injury in rabbits by inhibiting apoptosis

The one‑lung ventilation (OLV) technique is vital in thoracic surgery. However, it can result in severe lung injury, which is difficult to manage. The main solution at present is the use of ventilation strategies, including continuous positive oxygen pressure, low tidal volume and high frequency ventilation, and the administering of drugs, including phenylephrine, dexmedetomidine and morphine. However, the protective effect of these methods on the lungs is not sufficient to improve the prognosis of patients. Therefore, how to develop a novel protective drug remains an open question. Nicorandil, a mitochondrial (mito)KATP‑specific opener, serves an important role in cardioprotection, although its effect on lung injury remains unclear. The present study examined the protective role of nicorandil against collapse‑induced lung injury in rabbits undergoing OLV. Changes in arterial oxygen saturation (SaO2), arterial partial pressure for oxygen (PaO2), wet/dry weight ratio, and the microstructure of tissues and cells were observed. Enzyme‑linked immunosorbent assays were used to determine the concentrations of malondialdehyde (MDA) and tumor necrosis factor (TNF)‑α, and the activity of superoxide dismutase (SOD) in rabbits treated with nicorandil. Terminal deoxynucleotidyl transferase transfer‑mediated dUTP nick end‑labeling was used to detect apoptosis and western blotting was used to analyze the relative proteins involved in apoptosis. Western blotting and reverse transcription‑quantitative polymerase chain reaction analysis were used to examine the expression of hypoxia inducible factor 1α (HIF‑1α), phosphatidylinositol‑3‑kinase (PI3K), protein kinase B (Akt) and nuclear factor (NF)‑κB in the lungs of rabbits treated with nicorandil. The SaO2 and PaO2 in the high‑dose group were significantly higher than those in the control group in the process of OLV. The wet/dry weight ratio, and the concentrations of MDA and TNF‑α in the collapsed lung of the high‑dose group were significantly lower than those in the control group. The activity of SOD in the high‑dose group was significantly higher than that in the control group. The lung had improved microstructure and less apoptosis, which was determined by the Bax/Bcl2 ratio in the high‑dose group. The expression levels of PI3K, phosphorylated Akt and HIF‑1α were upregulated, whereas the expression of NF‑κB was downregulated. In conclusion, nicorandil had a protective effect via inhibiting apoptosis in non‑ventilated lung collapsed and re‑expansion during OLV in the rabbit. It acted on mitoKATP through the PI3K/Akt signaling pathway.

Targeting HIF-1α to Prevent Renal Ischemia-Reperfusion Injury: Does It Work?

Partial nephrectomy (open or minimally invasive) usually requires temporary renal arterial occlusion to limit intraoperative bleeding and improve access to intrarenal structures. This is a time-critical step due to the critical ischemia period of renal tissue. Prolonged renal ischemia may lead to irreversible nephron damage in the remaining tissue and, ultimately, chronic kidney disease. This is potentiated by the incompletely understood ischemia-reperfusion injury (IRI). A key mechanism in IRI prevention appears to be the upregulation of an intracellular transcription protein, Hypoxia-Inducible Factor (HIF). HIF mediates metabolic adaptation, angiogenesis, erythropoiesis, cell growth, survival, and apoptosis. Upregulating HIF-1α via ischemic preconditioning (IPC) or drugs that simulate hypoxia (hypoxia-mimetics) has been investigated as a method to reduce IRI. While many promising chemical agents have been trialed for the prevention of IRI in small animal studies, all have failed in human trials. The aim of this review is to highlight the techniques and drugs that target HIF-1α and ameliorate IRI associated with renal ischemia. Developing a technique or drug that could reduce the risk of acute kidney injury associated with renal IRI would have an immediate worldwide impact on multisystem surgeries that would otherwise risk ischemic tissue injury.

Impact of Deceased Donor Cardiac Arrest Time on Postpancreas Transplant Graft Function and Survival

Introduction

Transplantation of pancreas allografts from donors that have experienced preprocurement cardiopulmonary arrest (PPCA) is not common, though use of PPCA grafts is routine in liver and kidney transplantation. This article reviews a large number of PPCA pancreas grafts at a single center and reports posttransplant outcomes including early graft dysfunction, length of hospital stay, rejection, and early and late graft survival.

Methods

Preprocurement cardiopulmonary arrest, arrest time, and donor and recipient pancreatic enzyme levels were collected from electronic and written medical records. The PPCA donors were stratified into 4 groups: none, less than 20 minutes, 20-39 minutes, and 40 minutes or greater. Graft survival was assessed at 7 and 90 days and at 1 year. Long-term graft survival was assessed by Cox regression analysis.

Results

The records of 606 pancreas transplants were reviewed, including 328 (54%) simultaneous pancreas and kidney transplants. Preprocurement cardiopulmonary arrest occurred in 176 donors (29%; median time, 20 minutes). Median peak donor lipase was higher in PPCA donors (40 μ/L vs 29 μ/L, P = 0.02). Posttransplant, peak recipient amylase, and lipase levels were similar (P = 0.63). Prolonged arrest time (>40 minutes) was associated with higher donor peak lipase and lower recipient peak amylase (P = 0.05 for both). Stratified by donor arrest time, there was no difference in 7-day, 90-day, or 1-year graft survival. Cox regression comparing the 4 groups demonstrated no statistical difference in 10-year survival.

Conclusions

These results support transplantation of pancreas allografts from PPCA donors. Prolonged asystole was associated with higher peak donor serum lipase but lower peak recipient serum amylase. There were no differences in allograft survival.

Zinc preconditioning protects against renal ischaemia reperfusion injury in a preclinical sheep large animal model

Ischaemia-reperfusion injury (IRI) during various surgical procedures, including partial nephrectomy for kidney cancer or renal transplantation, is a major cause of acute kidney injury and chronic kidney disease. Currently there are no drugs or methods for protecting human organs, including the kidneys, against the peril of IRI. The aim of this study was therefore to investigate the reno-protective effect of Zn²⁺ preconditioning in a clinically relevant large animal sheep model of IRI. Further the reno-protective effectiveness of Zn²⁺ preconditioning was tested on normal human kidney cell lines HK-2 and HEK293. Anaesthetised sheep were subjected to uninephrectomy and 60 min of renal ischaemia followed by reperfusion. Sheep were preconditioned with intravenous injection of zinc chloride prior to occlusion. Serum creatinine and urea were measured before ischaemia and for 7 days after reperfusion. HK-2 and HEK293 cells were subjected to in vitro IRI using the oxygen- and glucose-deprivation model. Zn²⁺ preconditioning reduced ischaemic burden determined by creatinine and urea rise over time by ~ 70% in sheep. Zn²⁺ preconditioning also increased the survival of normal human kidney cells subjected to cellular stress such as hypoxia, hydrogen peroxide injury, and serum starvation. Overall, our protocol incorporating specific Zn²⁺ dosage, number of dosages (two), time of injection (24 and 4 h prior), mode of Zn²⁺ delivery (IV) and testing of efficacy in a rat model, a large preclinical sheep model of IRI and cells of human origin has laid the foundation for assessment of the benefit of Zn²⁺ preconditioning for human applications.

Ischemic preconditioning and remote ischemic preconditioning provide combined protective effect against ischemia/reperfusion injury

AIMS

Our objective was to compare the protective efficacy of ischemic preconditioning (IPC) and remote ischemic preconditioning (RIPC) against liver ischemia/reperfusion injury (IRI) and to evaluate their combined protective effect in mouse liver transplantation (MLT).

MATERIALS AND METHODS

Mice were randomly allocated to sham, IPC, RIPC, or IPC+RIPC groups. The animals were sacrificed at 2h, 24h, and 3 days after reperfusion. Blood samples were collected to evaluate alanine aminotransferase, TNF-α, and innate immune response. Liver tissue samples were obtained for histological evaluation, terminal deoxynucleotidyltransferased UTP nick end labeling, malondialdehyde (MDA) assay.

KEY FINDINGS

Mice given preconditioning measures had significantly lower increase in transaminase, TNF-α expression, MDA formation, liver injury scores, and apoptosis index at 2h, 24h and 3 days after liver transplantation. The percentages of CD11b(+), CD11b(+)CD16/32(+) and CD11b(+) CD16/32(high) in white blood cells at 3 days after MLT were significantly lower than in the sham group. The results of factorial analysis demonstrated no synergistic effect for IPC and RIPC, except for MDA formation 2h after reperfusion (p=0.038).

SIGNIFICANCE

Based on the synergistic and addictive effect on liver IRI induced by MLT between IPC and RIPC, the study suggested ways in which combined preconditionings could be elicited in patients undergoing planned procedures complicated by IRI to support better outcomes.

Progressive Evaluation of Apoptosis, Proliferation, and Angiogenesis in Fresh Rat Ovarian Autografts Under Remote Ischemic Preconditioning

This study evaluated the remote ischemic preconditioning (R-IPC) early and late repercussion on fresh ovarian transplants, aiming to assess a probable protective effect in ovarian follicular pool. Sixty Wistar EPM-1 rats were used, divided in 2 study groups: ovarian transplantation (Tx) and Tx + R-IPC, submitted to ovary transplant with or without R-IPC, respectively. These groups were subdivided according to the date for euthanasia: 4th, 7th, 14th, 21st, and 30th days of the postoperatory period. Morphology, morphometry, neoangiogenesis (vascular endothelial growth factor [VEGF]), proliferative activity (Ki-67), and apoptosis (cleaved caspase-3) were evaluated. Remote ischemic preconditioning was performed in the common iliac artery. Fresh autologous ovarian tissue was implanted integrally in the retroperitoneum. All animals showed resumption of estrous phase after ovary transplantation. Remote ischemic preconditioning attenuated the lesions progressively from the 7th day, with greater number of the immature follicles (14 days, P < .05), but didn't affect mature follicles and corpora lutea (P > .05). Immunohistochemical analyzes, taken as a whole, show that R-IPC benefic effect is more evident in the later periods of evaluation, when a greater proliferative activity (14, 21, and 30 days, P < .05) and lesser cell apoptotic activity (21 and 30 days, P < .05). The VEGF expression was similar in all times (P > .05). Remote ischemic preconditioning could have a benefic effect in the progressive evaluation of freshly grafted ovarian, especially on the latest phases of the posttransplant period. The 14th day was a landmark in the recuperation of the graft. Further investigations are necessary to determine the role of R-IPC in this scenario and its effect in frozen-thawed ovarian tissue.

Oxidative Stress and Lung Ischemia-Reperfusion Injury

Ischemia-reperfusion (IR) injury is directly related to the formation of reactive oxygen species (ROS), endothelial cell injury, increased vascular permeability, and the activation of neutrophils and platelets, cytokines, and the complement system. Several studies have confirmed the destructiveness of the toxic oxygen metabolites produced and their role in the pathophysiology of different processes, such as oxygen poisoning, inflammation, and ischemic injury. Due to the different degrees of tissue damage resulting from the process of ischemia and subsequent reperfusion, several studies in animal models have focused on the prevention of IR injury and methods of lung protection. Lung IR injury has clinical relevance in the setting of lung transplantation and cardiopulmonary bypass, for which the consequences of IR injury may be devastating in critically ill patients.

Safely expanding the donor pool: brain dead donors with history of temporary cardiac arrest

BACKGROUND & AIMS

Cardiac arrest (CA) in deceased organ donors can potentially be associated with ischaemic organ injury, resulting in allograft dysfunction after liver transplantation (LT). The aim of this study was to analyse the influence of cardiac arrest in liver donors.

METHODS

We evaluated 884 consecutive adult patients undergoing LT at our Institution from September 2003 to December 2011. Uni- and multivariable analyses was performed to identify predictive factors of outcome and survival for organs from donors with (CA donor) and without (no CA donor) a history of cardiac arrest.

RESULTS

We identified 77 (8.7%) CA donors. Median resuscitation time was 16.5 (1-150) minutes. Allografts from CA donors had prolonged CIT (p = 0.016), were obtained from younger individuals (p < 0.001), and had higher terminal preprocurement AST and ALT (p < 0.001) than those of no CA donors. 3-month, 1-year and 5-year survival for recipients of CA donor grafts was 79%, 76% and 57% and 72.1%, 65.1% and 53% for no CA donor grafts (log rank p = 0.435). Peak AST after LT was significantly lower in CA donor organs than in no CA donor ones (886U/l vs 1321U/l; p = 0.031). Multivariable analysis identified CIT as a risk factor for both patient and graft survival in CA donors.

CONCLUSION

This analysis represents the largest cohort of liver donors with a history of cardiac arrest. Reasonable selection of these donors constitutes a safe approach to the expansion of the donor pool. Rapid allocation and implantation with diminution of CIT may further improve the outcomes of livers from CA donors.

Activation of Nrf2 by ischemic preconditioning and sulforaphane in renal ischemia/reperfusion injury: a comparative experimental study

Objectives of the study were to investigate impact of ischemic preconditioning (Ipre) and sulforaphane (SFN) and combination of them on nuclear factor 2 erythroid related factor 2 (Nrf2) gene and its dependent genes, heme oxygenase-1 (HO1) and NADPH-quinone oxidoreductase1 (NQO-1) and inflammatory cytokines TNF-alpha, IL1beta, and intercellular adhesion molecule-1 (ICAM1) and caspase-3 in renal ischemia/reperfusion (I/R) injury. Ninety male Sprague Dawely rats were classified into 5 groups (each consists of 18 rats): sham, control, Ipre, sulforaphane and Sulfo+Ipre. Each group was subdivided into 3 subgroups each containing 6 rats according to time of harvesting kidney and taking blood samples; 24 h, 48 h, and 7 days subgroups. Renal functions including serum creatinine, BUN were measured at basal conditions and by the end of experiment. Expression of Nrf2, HO-1, NQO-1, TNF-alpha, IL-1beta, and ICAM-1 was measured by real time PCR in kidney tissues by the end of experiment. Also, immunohistochemical localization of caspase-3 and chemical assay of malondialdehyde (MDA), GSH and SOD activity were measured in kidney tissues. Both Ipre and SFN improved kidney functions, enhanced the expression of Nrf2, HO-1, and NQO-1, attenuated the expression of inflammatory (TNF-alpha, IL-1, and ICAM-1) and apoptotic (caspase-3) markers. However, the effect of sulforaphane was more powerful than Ipre. Also, a combination of them caused more improvement in antioxidant genes expression and more attenuation in inflammatory genes but not caspase-3 than each one did separately. Sulforaphane showed more powerful effect in renoprotection against I/R injury than Ipre as well as there might be a synergism between them at the molecular but not at the function level.

The effect of remote ischemic postconditioning on graft function in patients undergoing living donor kidney transplantation

BACKGROUND

We evaluated whether remote ischemic postconditioning (RiPoC) could improve initial graft function in living donor kidney transplantation (KT).

METHODS

Patients undergoing living donor KT were randomly assigned to either RiPoC (n=30) or control group (n=30). Immediately after reperfusion in the RiPoC group, three cycles of ischemia and reperfusion, lasting 5 min each, were performed on one upper limb. Renal function was assessed before surgery, 2 hr after surgery, and at 12-hr intervals for 96 hr postsurgery by measuring serum creatinine (sCr) and the estimated glomerular filtration rate (eGFR). Urine output and urine creatinine were assessed until postoperative day 7, and hospital stay and complication rates were compared.

RESULTS

The time for sCr to reach 50% of its preoperative level was significantly shorter in the RiPoC group than in the control group [12 (12-24) hr for RiPoC vs. 24 (21-36) hr for the control, P=0.005]. The number of patients whose sCr was reduced by 50% within 24 hr was significantly greater in the RiPoC group than in the control group [n=26 (87%) in RiPoC vs. n=18 (60%) in control, P=0.020]. However, there were no differences in sCr and eGFR thereafter, the incidence of graft dysfunction or complication rates between groups.

CONCLUSION

In this study, RiPoC appeared to hasten the recovery of graft function within 24 hr but did not affect the graft function thereafter. However, considering most recipients had immediate graft function, further studies with deceased donors or studies powered to detect a smaller difference are needed.

Some mechanisms of the protective effect of ischemic preconditioning on rat liver ischemia-reperfusion injury

Ischemia-reperfusion (I/R) injury is a multifactorial process that affects graft function after liver transplantation. An understanding of the mechanisms involved in I/R injury is essential for the design of therapeutic strategies to improve the outcome of liver transplantation. The generation of reactive oxygen species subsequent to reoxygenation inflicts tissue damage and initiates a cascade of deleterious cellular responses, leading to inflammation, cell death, and ultimate organ failure. Increasing experimental evidence has suggested that Kupffer cells and T-cells mediate activation of neutrophil inflammatory responses. Activated neutrophils infiltrate the injured liver in parallel with increased expression of adhesion molecules on endothelial cells. The heme oxygenase system is among the most critical of the cytoprotective mechanisms activated during cellular stress, exerting antioxidant and anti-inflammatory functions, modulating the cell cycle, and maintaining the microcirculation. Finally, the activation of toll-like receptors on Kupffer cells may play a fundamental role in exploring new therapeutic strategies based on the concept that hepatic I/R injury represents a case for host “innate” immunity. In the present study, there was a significant decrease in hepatic activity of glycogen in the I/R group as compared with corresponding values in the control group. On the other hand, there was a significant increase in the hepatic activity of glycogen in the I/R-IP (ischemic preconditioning) group as compared with corresponding values in the I/R group.

Angiotensin II removes kidney resistance conferred by ischemic preconditioning

Ischemic preconditioning (IPC) by ischemia/reperfusion (I/R) renders resistance to the kidney. Strong IPC triggers kidney fibrosis, which is involved in angiotensin II (AngII) and its type 1 receptor (AT1R) signaling. Here, we investigated the role of AngII/AT1R signal pathway in the resistance of IPC kidneys to subsequent I/R injury. IPC of kidneys was generated by 30 minutes of bilateral renal ischemia and 8 days of reperfusion. Sham-operation was performed to generate control (non-IPC) mice. To examine the roles of AngII and AT1R in IPC kidneys to subsequent I/R, IPC kidneys were subjected to either 30 minutes of bilateral kidney ischemia or sham-operation following treatment with AngII, losartan (AT1R blocker), or AngII plus losartan. IPC kidneys showed fibrotic changes, decreased AngII, and increased AT1R expression. I/R dramatically increased plasma creatinine concentrations in non-IPC mice, but not in IPC mice. AngII treatment in IPC mice resulted in enhanced morphological damage, oxidative stress, and inflammatory responses, with functional impairment, whereas losartan treatment reversed these effects. However, AngII treatment in non-IPC mice did not change I/R-induced injury. AngII abolished the resistance of IPC kidneys to subsequent I/R via the enhancement of oxidative stress and inflammatory responses, suggesting that the AngII/AT1R signaling pathway is associated with outcome in injury-experienced kidney.

[Ischemia-reperfusion injury after lung transplantation]

Lung ischemia-reperfusion is characterized by diffuse alveolar damage arising from the first hours after transplantation. The first etiology of the primary graft dysfunction in lung is ischemia-reperfusion. It is burdened by an important morbi-mortality. Lung ischemia-reperfusion increases the oxidative stress, inactivates the sodium pump, increases the intracellular calcium, leads to cellular death and the liberation of pro-inflammatory mediators. Researches relative to the reduction of the lung ischemia-reperfusion injuries are numerous but few of them found a place in common clinical practice, because of an insufficient level of proofs. Ex vivolung evaluation is a suitable technique in order to evaluate therapeutics supposed to limit lung ischemia-reperfusion injuries.

Ischemia/reperfusion Injury and its Consequences on Immunity and Inflammation

Ischemia/reperfusion injury (IRI), an inherent component of transplantation, affects organ quality and transplant outcomes. Although the complexity of the pathophysiology is recognized, detailed mechanisms remain unclear, and strategies preventing the consequences of IRI have been challenging. Of critical significance appears the link between IRI, the initiation of innate immune responses, and the (potential) augmentation of adaptive immunity. An improved understanding of those complex mechanisms and interactions may pave the way for more effective treatment strategies.

Activation of nuclear factor erythroid 2-related factor 2 (Nrf2) and Nrf-2-dependent genes by ischaemic pre-conditioning and post-conditioning: new adaptive endogenous protective responses against renal ischaemia/reperfusion injury

AIM

To investigate the impact of ischaemic pre-conditioning (Ipre) and post-conditioning (Ipost) on expression of nuclear factor erythroid 2-related factor 2 (Nrf2) gene and its dependent genes, haem oxygenase-1 (HO-1) and NADPH-quinone oxidoreductase-1 (NQO-1); inflammatory cytokines TNF-α, IL1β and ICAM-1; and apoptotic markers such as caspase-3 in renal ischaemia/reperfusion (I/R) injury.

METHODS

One hundred and fifty male Sprague Dawley rats were classified into five groups (each consisted of 30 rats): sham, control (I/R), Ipre + I/R, Ipre without I/R and Ipost + I/R. Serum creatinine and blood urea nitrogen (BUN) were measured at 2, 24 and 48 h after ischaemia. In kidney tissues, mRNA of Nrf2, HO-1, NQO-1, TNF-α, IL-1β and ICAM-1 and immunohistochemical expression of Nrf2 and caspase-3 were assessed.

RESULTS

Serum creatinine and BUN improved significantly in Pre + I/R group; however, they did not show any significant improvement in Post + I/R group. Also, Ipre-I/R group showed non-significant change in serum creatinine and BUN. The expression of Nrf2, HO-1 and NQO-1 is increased significantly in Pre + I/R and Pre - I/R groups, while the enhancement in Post + I/R group was non-significant. Moreover, the expression of proinflammatory cytokines (TNF-α, IL-1 and ICAM-1) and apoptotic (caspase-3) markers showed high significant attenuation in Pre + I/R group, but slight significant attenuation in Pre + I/R group.

CONCLUSION

The renoprotective action of Ipre might include early activation and enhanced expression of Nrf2 gene and its dependent antioxidant genes, HO-1 and NOQ1, as endogenous adaptive renoprotective genes, as well as reduction in TNF-α, IL-1β, ICAM-1 and caspase-3.

Protection against renal ischaemia/reperfusion injury: A comparative experimental study of the effect of ischaemic preconditioning vs. postconditioning

Objective

To compare the effect of ischaemic preconditioning (Ipre) vs. ischaemic postconditioning (Ipost) on renal ischaemia/reperfusion (I/R) injury in rats.

Materials and methods

In all, 120 male Sprague–Dawley rats were classified into four groups of 30 rats each, designated sham, control, Ipre and Ipost. Renal function, including serum creatinine, blood urea nitrogen (BUN), creatinine clearance (CrCl), fractional Na excretion (FENa) and renal histopathology were measured at 2, 24 and 48 h after ischaemia. Markers of lipid peroxidation (malondialdehyde, MDA), superoxide dismutase (SOD) and reduced glutathione (GSH) were measured in kidney tissues during the same intervals.

Results

Ipre caused a significant improvement in renal function, as indicated by a significant decrease in serum creatinine, BUN and FENa, with a significant increase in CrCl. However, Ipost caused no significant improvement in renal function. Morphologically Ipre caused a marked significant improvement in the renal tubular damage score compared to Ipost. Also, Ipre caused a significant decrease in MDA, and significant increase in GSH and SOD when compared to Ipost.

Conclusion

Ipre is more potent than Ipost for improving the renal injury induced by I/R. Ipre caused a marked improvement in renal function and morphology, while Ipost caused a minimal improvement in morphology only. Moreover, Ipre caused a marked and significant reduction in oxidative stress in kidney tissues, while Ipost caused a minimal reduction.

Flavin mononucleotide-based fluorescent proteins function in mammalian cells without oxygen requirement

Usage of the enhanced green fluorescent protein (eGFP) in living mammalian cells is limited to aerobic conditions due to requirement of oxygen during chromophore formation. Since many diseases or disease models are associated with acute or chronic hypoxia, eGFP-labeling of structures of interest in experimental studies might be unreliable leading to biased results. Thus, a chromophore yielding a stable fluorescence under hypoxic conditions is desirable. The fluorescence of flavin mononucleotide (FMN)-based fluorescent proteins (FbFPs) does not require molecular oxygen. Recently, the advantages of FbFPs for several bacterial strains and yeasts were described, specifically, their usage as a real time fluorescence marker in bacterial expression studies and their ability of chromophore formation under anaerobic conditions. Our objective was to verify if FbFPs also function in mammalian cells in order to potentially broaden the repertoire of chromophores with ones that can reliably be used in mammalian studies under hypoxic conditions. In the present study, we demonstrate for the first time, that FbFPs can be expressed in different mammalian cells, among them murine neural stem cells during proliferative and differentiated stages. Fluorescence intensities were comparable to eGFP. In contrast to eGFP, the FbFP fluorescence did not decrease when cells were exposed to defined hypoxic conditions neither in proliferating nor in differentiated cells. Thus, FbFPs can be regarded as an alternative to eGFP in studies that target cellular structures which are exposed to hypoxic conditions.

Combined preconditioning and postconditioning provides synergistic protection against liver ischemic reperfusion injury

Hepatic Ischemia and Reperfusion Injury (IRI) is a major cause of liver damage during liver surgery and transplantation. Ischemic preconditioning and postconditioning are strategies that can reduce IRI. In this study, different combined types of pre- and postconditioning procedures were tested in a murine warm hepatic IRI model to evaluate their protective effects. Proanthocyanidins derived from grape seed was used before ischemia process as pharmacological preconditioning to combine with technical preconditioning and postconditioning. Three pathways related to IRI, including reactive oxygen species (ROS) generation, pro-inflammatory cytokines release and hypoxia responses were examined in hepatic IRI model. Individual and combined pre- and postconditioning protocols significantly reduce liver injury by decreasing the liver ROS and cytokine levels, as well as enhancing the hypoxia tolerance response. Our data also suggested that in addition to individual preconditioning or postconditioning, the combination of these two treatments could reduce liver ischemia/reperfusion injury more effectively by increasing the activity of ROS scavengers and antioxidants. The utilization of grape seed proanthocyanidins (GSP) could improve the oxidation resistance in combined pre- and postconditioning groups. The combined protocol also further increased the liver HIF-1 alpha protein level, but had no effect on pro-inflammatory cytokines release compared to solo treatment.

Role of Mitogen-Activated Protein Kinases in Myocardial Ischemia-Reperfusion Injury during Heart Transplantation

In solid organ transplantation, ischemia/reperfusion (IR) injury during organ procurement, storage and reperfusion is an unavoidable detrimental event for the graft, as it amplifies graft inflammation and rejection. Intracellular mitogen-activated protein kinase (MAPK) signaling pathways regulate inflammation and cell survival during IR injury. The four best-characterized MAPK subfamilies are the c-Jun NH2-terminal kinase (JNK), extracellular signal- regulated kinase-1/2 (ERK1/2), p38 MAPK, and big MAPK-1 (BMK1/ERK5). Here, we review the role of MAPK activation during myocardial IR injury as it occurs during heart transplantation. Most of our current knowledge regarding MAPK activation and cardioprotection comes from studies of preconditioning and postconditioning in nontransplanted hearts. JNK and p38 MAPK activation contributes to myocardial IR injury after prolonged hypothermic storage. p38 MAPK inhibition improves cardiac function after cold storage, rewarming and reperfusion. Small-molecule p38 MAPK inhibitors have been tested clinically in patients with chronic inflammatory diseases, but not in transplanted patients, so far. Organ transplantation offers the opportunity of starting a preconditioning treatment before organ procurement or during cold storage, thus modulating early events in IR injury. Future studies will need to evaluate combined strategies including p38 MAPK and/or JNK inhibition, ERK1/2 activation, pre- or postconditioning protocols, new storage solutions, and gentle reperfusion.

Poly-IC preconditioning protects against cerebral and renal ischemia-reperfusion injury

Preconditioning induces ischemic tolerance, which confers robust protection against ischemic damage. We show marked protection with polyinosinic polycytidylic acid (poly-IC) preconditioning in three models of murine ischemia-reperfusion injury. Poly-IC preconditioning induced protection against ischemia modeled in vitro in brain cortical cells and in vivo in models of brain ischemia and renal ischemia. Further, unlike other Toll-like receptor (TLR) ligands, which generally induce significant inflammatory responses, poly-IC elicits only modest systemic inflammation. Results show that poly-IC is a new powerful prophylactic treatment that offers promise as a clinical therapeutic strategy to minimize damage in patient populations at risk of ischemic injury.

Ischemic preconditioning reduces endoplasmic reticulum stress and upregulates hypoxia inducible factor-1α in ischemic kidney: the role of nitric oxide

Background

Although recent studies indicate that renal ischemic preconditioning (IPC) protects the kidney from ischemia-reperfusion (I/R) injury, the precise protective mechanism remains unclear. In the current study, we investigated whether early IPC could upregulate hypoxia inducible transcription factor-1α (HIF-1α) expression and could reduce endoplasmic reticulum (ER) stress after renal I/R and whether pharmacological inhibition of nitric oxide (NO) production would abolish these protective effects.

Methods

Kidneys of Wistar rats were subjected to 60 min of warm ischemia followed by 120 min of reperfusion (I/R group), or to 2 preceding cycles of 5 min ischemia and 5 min reperfusion (IPC group), or to intravenously injection of N^G-nitro-L-arginine methylester (L-NAME, 5 mg/kg) 5 min before IPC (L-NAME+IPC group). The results of these experimental groups were compared to those of a sham-operated group. Sodium reabsorption rate, creatinine clearance, plasma lactate dehydrogenase (LDH) activity, tissues concentrations of malonedialdehyde (MDA), HIF-1α and nitrite/nitrate were determined. In addition, Western blot analyses were performed to identify the amounts of Akt, endothelial nitric oxide synthase (eNOS) and ER stress parameters.

Results

IPC decreased cytolysis, lipid peroxidation and improved renal function. Parallely, IPC enhanced Akt phosphorylation, eNOS, nitrite/nitrate and HIF-1α levels as compared to I/R group. Moreover, our results showed that IPC increased the relative amounts of glucose-regulated protein 78 (GRP78) and decreased those of RNA activated protein kinase (PKR)-like ER kinase (PERK), activating transcription factor 4 (ATF4) and TNF-receptor-associated factor 2 (TRAF2) as judged to I/R group. However, pre treatment with L-NAME abolished these beneficial effects of IPC against renal I/R insults.

Conclusion

These findings suggest that early IPC protects kidney against renal I/R injury via reducing oxidative and ER stresses. These effects are associated with phosphorylation of Akt, eNOS activation and NO production contributing thus to HIF-1α stabilization. The beneficial impact of IPC was abolished when NO production is inhibited before IPC application.

Ischemic preconditioning-like effect of polyunsaturated fatty acid-rich diet on hepatic ischemia/reperfusion injury

AIM

The aim of this study was to investigate a possible preconditioning effect of oral diet enriched with polyunsaturated fatty acids (PUFAs) on liver ischemia/reperfusion (I/R) injuries.

METHODS

Wistar male rats were fed a standard diet or polyunsaturated fatty acid-rich diet (PRD) enriched with (GII) or without (GIII) ω-3 PUFA. Rats were submitted to partial liver ischemia during 1 h and evaluated in pre- and post-I/R conditions. In pre-I/R condition, livers were collected for determination of fatty acid composition, liver mitochondrial function, malondialdehyde (MDA) content, and histological analysis. Four hours after liver reperfusion serum activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT), serum levels of tumor necrosis factor-alpha, interleukin-6, interleukin-10, and prostaglandin-E2, liver mitochondrial function, MDA content, and histology were evaluated.

RESULTS

In the pre-I/R condition, GII and GIII groups had an increase on PUFA content and exhibited slight increased macrosteatosis and microsteatosis in the liver. After 4 h of reperfusion, PRD-fed rats showed a marked decrease on steatosis, diminished necrosis, an increase in MDA formation, and mitochondrial uncoupling. We also observed a marked decrease in plasma levels of cytokines and ALT and AST activities in post-I/R condition in PRD groups.

CONCLUSION

In this experimental model in the rat, PRD has a preconditioning effect protecting the liver from I/R injury and should be object of future clinical studies.

Ischemic preconditioning and remote ischemic preconditioning have protective effect against cold ischemia-reperfusion injury of rat small intestine

PURPOSE

To investigate the protective effect of ischemic preconditioning (IPC) and remote ischemic preconditioning (RIPC) against cold ischemia-reperfusion injury (IRI) associated with small bowel transplantation (SBT).

METHODS

Male Lewis rats weighing 200-300 g were used for this study. The rats were assigned to three groups: control, ischemic preconditioning (IPC), or remote ischemic preconditioning (RIPC). Heterotopic SBT was thereafter performed. The recipient rats were killed 3, 6, 12 and 24 h after transplantation. Specimens from the intestine were histologically scored according to a grading system (Park et al.). Serum lactate dehydrogenase (LDH), aspirate aminotransferase (AST), alanine aminotransferase (ALT) were examined and heme oxygenase-1 (HO-1) were analyzed by ELISA where HO-1 served as an indicator of protection against IRI.

RESULTS

The values of tissue injury were significantly lower in the IPC and RIPC groups than in control group at 3 h after SBT. The serum LDH, AST and ALT levels also significantly decreased in the IPC and RIPC groups at 3 h after SBT, but these protective effects against cold IRI diminished by 12 and 24 h after SBT. The serum HO-1 level significantly increased in the IPC and RIPC groups 3 h after SBT.

CONCLUSION

Both IPC and RIPC were found to ameliorate ischemia-reperfusion injury after rat SBT in the early phase. HO-1 may therefore play a protective role against cold IRI.

Ischemic preconditioning of the graft for intestinal transplantation in rats

To test the hypothesis that two modalities of IPC should decrease acute rejection and BT after SBTx in rats. Orthotopic allogenic SBTx was performed from Wistar to BN. IPC was performed by 2 ' and 5 ' superior mesenteric artery clamping, following 2-min and 5-min reperfusion before graft cooling and retrieving. Donor-recipient sets were randomly allocated to five groups: IPC2m4d, IPC2m7d, IPC5min7d, and the control groups for the two end points; ctrl4d and ctrl7d. IRI, rejection, and BT were assessed after four or seven days depending on the groups. Measured variables included: histology, leukocyte activation by tissue MPO determination, and proinflammatory cytokines (IL-b and TNF-α) to assess inflammatory response. Leukocyte activation was significantly reduced in IPC2m7d in comparison with Ctrl and IPC5min7d. Rejection tended to be lower in IPC2min7d. Cytokine levels were contradictory and not consistent with histology. Finally, BT was less frequent in IPC2min4d group but this benefit was missed in animals with rejection (7d). Inflammatory response (MPO) was reduced and rejection tended to be lower after in IPC2m7d. Bacterial translocation was reduced in IPC2min4d but the benefit was missed at day 7.

Comparison of biological features of L-02 hepatocytes undergoing subzero nonfreezing storage in UW solution, Celsior solution or HTK solution for use in bioartificial liver system

AIM: To compare the biological features of L-02 hepatocytes undergoing subzero nonfreezing storage in University of Wisconsin (UW) solution, Celsior solution, and histidine-tryptophan-ketoglutarate (HTK) solution for use in bioartificial liver system.

METHODS: L-02 hepatocytes were divided into three groups: UW group, CS group, and HTK group. After 72 h of hypothermic storage, cell viability and death, alanine aminotransferase (ALT) and lactate dehydrogenase (LDH) release, and the ability of hepatocytes to synthesize urea and secrete albumin were measured.

RESULTS: After 72 h of hypothermic storage, cells of the UW group had higher cell viability rate (71.10% ± 4.09% vs 65.22% ± 4.45%, 50.48% ± 5.13%, both P < 0.05), lower cell death rate (29.90% ± 4.09% vs 34.78% ± 4.45%, 49.52% ± 5.13%, both P < 0.05), less release of ALT (6.18 U/L ± 1.36 U/L vs 8.15 U/L ± 1.14 U/L, 9.75 U/L ± 2.45 U/L, both P < 0.05) and LDH (93.82 U/L ± 5.68U/L vs 115.67 U/L ± 8.77 U/L, 164.92 U/L ± 15.95 U/L, both P < 0.05), and better ability to synthesize urea (1.08 mmol/L ± 0.22 mmol/L vs 0.92 mmol/L ± 0.17 mmol/L, 0.68 mmol/L ± 0.08 mmol/L, both P < 0.05) and secrete albumin (9.33 mg/L ± 1.36 mg/L vs 7.54 mg/L ± 1.22 mg/L, 7.18 mg/L ± 0.93 mg/L, both P < 0.05) than those of the CS and HTK groups.

CONCLUSION: L-02 hepatocytes undergoing subzero nonfreezing storage in UW solution could provide higher cell viability rate, lower ALT and LDH release, and better ability to synthesize urea and secrete albumin than those stored in CS or HTK solution.

Study on the vaginal smear of rats submitted to autologous ovarian transplant: impact of remote ischemic preconditioning

PURPOSE

To evaluate the remote ischemic preconditioning (R-IPC) impact on the quality of the ovarian graft by means of vaginal smear of transplanted rats.

METHODS

Sixty rats were used divided in six groups: Control; Fresh transplant (TxF); Cryopreserved transplant (TxC); R-IPC; R-IPC + fresh transplant (TxF+R-IPC); R-IPC + cryopreserved transplant (TxC+R-IPC). R-IPC was performed in the common iliac artery. Autologous ovarian tissue was implanted integrally in the retro peritoneum. On the first PO day, vaginal smear collection was daily initiated. After 30 days, the PO day when the estrous cycle was re-initiated was considered for analysis as well as the estrous days and the number of estrous cycles.

RESULTS

R-IPC showed a tendency to an early estrus re-initiation (p>0.05) as well as increase the number of cycles in the fresh transplanted group while in the cryopreserved transplant the number of cycles was similar, regardless of the stimulus R-IPC (p>0.05). The animals which had undergone fresh grafts had a longer estrous period than the ones which had undergone cryopreserved grafts, with or without R-IPC (p<0.05).

CONCLUSION

R-IPC promoted earlier re-initiation of ovarian activity in the PO and greater estrous frequency, with more consistent results in the fresh grafts than in the cryopreserved ones.

Non-invasive limb ischemic pre-conditioning reduces oxidative stress and attenuates myocardium ischemia-reperfusion injury in diabetic rats

This study was to explore whether repeated non-invasive limb ischemic pre-conditioning (NLIP) can confer an equivalent cardioprotection against myocardial ischemia-reperfusion (I/R) injury in acute diabetic rats to the extent of conventional myocardial ischemic pre-conditioning (MIP) and whether or not the delayed protection of NLIP is mediated by reducing myocardial oxidative stress after ischemia-reperfusion. Streptozotocin-induced diabetic rats were randomized to four groups: Sham group, the I/R group, the MIP group and the NLIP group. Compared with the I/R group, both the NLIP and MIP groups showed an amelioration of ventricular arrhythmia, reduced myocardial infarct size, increased activities of total superoxide dismutase (SOD), manganese-SOD and glutathione peroxidase, increased expression of manganese-SOD mRNA and decreased xanthine oxidase activity and malondialdehyde concentration (All p < 0.05 vs I/R group). It is concluded that non-invasive limb ischemic pre-conditioning reduces oxidative stress and attenuates myocardium ischemia-reperfusion injury in diabetic rats.

Role of heme oxygenase-1 in transplantation

Heme oxygenase-1 (HO-1) is the rate-limiting enzyme in heme catabolism that converts heme to Fe++, carbon monoxide and biliverdin. HO-1 acts anti-inflammatory and modulates apoptosis in many pathological conditions. In transplantation, HO-1 is overexpressed in organs during brain death, when undergoing ischemic damage and rejection. However, intentionally induced, it ameliorates pathological processes like ischemia reperfusion injury, allograft, xenograft or islet rejection, facilitates donor specific tolerance and alleviates chronic allograft changes. We herein consistently summarize the huge amount of data on HO-1 and transplantation that have been generated in multiple laboratories during the last 15years and suggest possible clinical implications and applications for the near future.

Subzero nonfreezing storage of C3A hepatocytes for use in bioartificial liver support systems

AIM: To investigate whether subzero nonfreezing storage (-0.8 °C) is superior to conventional cold storage in preservation of C3A hepatocytes for use in bioartificial liver support systems.

METHODS: C3A hepatocytes suspended in University of Wisconsin (UW) solution were divided into three groups: subzero nonfreezing group (-0.8 °C), zero nonfreezing group (0 °C) and control group (4 °C). After 24, 48 and 72 hours of hypothermic storage, cell viability and apoptosis were detected by flow cytometry; intracellular adenosine triphosphate (ATP) content, lactate dehydrogenase (LDH) release, lactic acid production, urea synthesis and albumin secretion were determined; and cell morphological changes were observed.

RESULTS: Compared to the zero nonfreezing group and the control group, after 72 hours of hypothermic storage, the percentage of viable C3A hepatocytes was significantly higher (86.49% ± 2.80% vs 81.50% ± 2.83% and 77.83% ± 3.40%, respectively; both P < 0.05), and cell apoptosis rate was significantly lower (1.26% ± 0.84% vs 5.34% ± 1.20% and 9.16% ± 1.99%, respectively; both P < 0.05) in the subzero nonfreezing group. Lactic acid and LDH production was more significantly suppressed (lactic acid: 10.38 μg/10⁶ cells ± 1.40 μg/10⁶ cells vs 12.02 μg/10⁶ cells ± 1.64 μg/106 cells and 17.41 μg/10⁶ cells ± 2.40 μg/10⁶ cells; LDH: 80.10 U/L ± 11.10 U/L vs 120.04 U/L ± 14.32 U/L and 148.98 U/L ± 15.37 U/L, respectively; all P < 0.05), and the ability of hepatocytes to synthesize urea and secrete albumin was better maintained in the subzero nonfreezing group (both P < 0.05). Moreover, cells in the subzero nonfreezing storage group had lower death rate and better cellular morphology. A burr-like structure around the cell membrane and an intracellular vacuole-like structure were found in cells in the zero nonfreezing group and the control group, but not in the subzero nonfreezing group.

CONCLUSION: Subzero nonfreezing storage (-0.8 °C) of hepatocytes to construct a "ready-to-use" hepatocyte bank like the "blood bank" will efficiently promote the development of bioartificial liver support systems.

Searching for NF-kappaB-based treatments of ischemia reperfusion injury

When a tissue becomes ischemic, a host of changes occur at the cellular level that lead to a shift in transcriptional activity of many inflammatory and cytoprotective compounds, a process which is extensively controlled through a family of transcription factors known as nuclear factor kappa-B (NF-kappaB). This shift in activity paradoxically results in both a cytoprotective effect at the cellular level and upon reperfusion, a generally destructive inflammatory response, a phenomenon referred to as ischemia reperfusion (IR) injury. To date, a number of methods of modifying the activity of NF-kappaB through either physiologic or pharmacologic manipulation have been developed and studied in animal models of IR injury and in some cases in human clinical trials. Nearly every method of NF-kappaB antagonism has demonstrated a discrete protective effect allowing investigators to reduce myocardial infarct sizes by 60% and cerebral infarct sizes by 57% relative to untreated control animals. The problem of IR injury is all too common and represents a discrete threat not only to the tissues directly involved in the ischemic event, but also to distal sites as well as is seen in the evolution of acute respiratory distress and severe inflammatory response syndromes. In the course of this review, the nature of NF-kappaB and its involvement in IR injury is examined along with the efficacy of the various NF-kappaB-based investigational treatment developed to date.

Attenuation of renal ischemia-reperfusion injury by postconditioning involves adenosine receptor and protein kinase C activation

SUMMARY

Significant organ injury occurs after transplantation and reflow (i.e., reperfusion injury). Postconditioning (PoC), consisting of alternating periods of reperfusion and re-occlusion at onset of reperfusion, attenuates reperfusion injury in organs including heart and brain. We tested whether PoC attenuates renal ischemia-reperfusion (I/R) injury in the kidney by activating adenosine receptors (AR) and protein kinase C (PKC). The single kidney rat I/R model was used. Groups: (1) sham: time-matched surgical protocol only. In all others, the left renal artery (RA) was occluded for 45 min and reperfused for 24 h. (2) CONTROL: I/R with no intervention at R. All antagonists were administered 5 min before reperfusion. (3) PoC: I/R + four cycles of 45 s of R and 45 s of re-occlusion before full R. (4) PoC + ARi: PoC plus the AR antagonist 8-rho-(sulfophenyl) theophylline (8-SPT). (5) PoC + PKCi: PoC plus the PKC antagonist chelerythrine (Che). In shams, plasma blood urea nitrogen (BUN mg/dl) at 24 h averaged 23.2 +/- 5.3 and creatinine (Cr mg/dl) averaged 1.28 +/- 0.2. PoC reduced BUN (87.2 +/- 10 in CONTROL vs. 38.8 +/- 9, P = 0.001) and Cr (4.2 +/- 0.6 in CONTROL vs. 1.5 +/- 0.2, P < 0.001). 8-SPT and Che reversed renal protection indices after PoC. I/R increased apoptosis, which was reduced by PoC, which was reversed by 8-SPT and Che. Postconditioning attenuates renal I/R injury by adenosine receptor activation and PKC signaling.

Prevention of I/R injury in fatty livers by ischemic preconditioning is associated with increased mitochondrial tolerance: the key role of ATPsynthase and mitochondrial permeability transition

Ischemia/reperfusion (I/R) injury is a commonly encountered clinical problem and occurs probably as a consequence of irreversible mitochondrial injury. The increased susceptibility of fatty livers to ischemic injury is associated with depletion of adenosine triphosphate (ATP) content, which is preserved by preconditioning. Mitochondria being the main ATP production source for the cell, we aimed to evaluate whether ischemic preconditioning (IPC) of fatty livers prevents the impairment in mitochondrial function induced by I/R. Lean and steatotic animals were subjected to 90 min of hepatic warm ischemia and 12 h of reperfusion. IPC effect was tested in fatty livers. After reperfusion, serum alanine aminotransferase (ALT) and aspartate aminotransferase (AST) levels were measured. Mitochondrial membrane potential, mitochondrial respiration and susceptibility to mitochondrial permeability transition (MPT) were evaluated, as well as ATPase activity and adenine nucleotides. IPC of fatty livers decreased serum AST and ALT levels. Fatty animals subjected to I/R exhibited decreased mitochondrial membrane potential and a delay in the repolarization after a phosphorylation cycle, associated with increased state 4 respiration. Increased tolerance to MPT induction, preservation of F(1)F(o)-ATPsynthase activity and mitochondrial bioenergetics were observed in ischemic preconditioned fatty livers. Thus, IPC is an endogenous protecting mechanism that preserves mitochondrial function and bioenergetics in fatty livers.