Comparison of protective effects of trimetazidine against experimental warm ischemia of different durations: early and long-term effects in a pig kidney model

Ethnopharmacological basis for traditional use of Tradescantia spathaceae as nephroprotective agent via in vitro, in vivo and molecular docking techniques

ETHNOPHARMACOLOGICAL RELEVANCE

Tradescantia spathaceae Sw. (commonly referred to as the oyster plant, boat lily, or Moses in a basket) is classified within the family Commelinaceae. The fresh infusion of this plant is utilized for addressing renal issues. Its foliage is employed in the management of kidney stones, renal discomfort, kidney infections, and dysuria.

AIM OF STUDY

The aim of this research was to conduct pharmacological validation of T. spathaceae in relation to the treatment of disorders affecting the urinary system. In-vivo, in-vitro, and in-silico investigations were designed to demonstrate the possible advantages of T. spathaceae in renal protection and diuresis.

METHODOLOGY

The pharmacologically active constituents of the ethanoic extract of T. spathaceae were analysed utilizing High-Performance Liquid Chromatography (HPLC). In-vivo experiments were directed to evaluate the potential benefits of T. spathaceae in facilitating diuresis, safeguarding the kidneys from cisplatin-induced toxicity, and inducing spasms in isolated bladder tissues to clarify its spasmolytic properties.

RESULTS

HPLC analysis of the hydroethanolic extract of T. spathaceae identified gallic acid, vanillic acid, and p-coumaric acid. This extract showed dose dependent relaxation of contractions induced by carbachol (1 μM), acetylcholine (Ach) (1 μM), and low potassium (25 mmol) in isolated strips of the urinary bladder. Its spasmolytic effects were comparable to the standard agents atropine and oxybutynin. In vivo studies demonstrated the extract's protective effects on the kidneys, along with anti-inflammatory and diuretic properties. Additionally, it offered protection against cisplatin-induced toxicity while promoting diuresis.

CONCLUSION

TSCR exhibited nephroprotective effects through diuretic, anti-inflammatory, and anti-muscarinic actions.

New insights on pharmacological and therapeutic potentials of trimetazidine beyond anti-anginal drug: A comprehensive review

Trimetazidine (TMZ) is a beneficial and well-tolerable anti-anginal drug which has protective action towards ischemia and reperfusion injury. TMZ performs its anti-ischemic effect by modifying cardiac metabolism without shifting the hemodynamic functions, so it represents an outstanding complementary perspective to the general angina treatment. TMZ possesses a positive impact on the inflammatory profile, and also endothelial function furthermore displays various benefits through minimising the number, as well as the intensity of angina strikes and ameliorating the clinical indication and symptoms of myocardium ischemia. It is administrated as monotherapy along with a combination of different antianginal drugs. Apart from anti-angina action, in recent years TMZ has shown various pharmacological activities such as neuroprotective, renal protective, hepato-protective, cardio-protective effects, and other beneficial pharmacological activities. We select to write the present review article to cover the different pharmacological and therapeutic potentials of TMZ.

Protective Effects of Trimetazidine and Dexmedetomidine on Liver Injury in a Mesenteric Artery Ischemia-Reperfusion Rat Model via Endoplasmic Reticulum Stress

BACKGROUND/OBJECTIVES

Acute mesenteric ischemia can lead to severe liver damage due to ischemia-reperfusion (I/R) injury. This study investigated the protective effects of trimetazidine (TMZ) and dexmedetomidine (DEX) against liver damage induced by mesenteric artery I/R via endoplasmic reticulum stress (ERS) mechanisms.

METHODS

Twenty-four rats were divided into four groups: control, I/R, I/R+TMZ, and I/R+DEX. TMZ (20 mg/kg) was administered orally for seven days, and DEX (100 µg/kg) was given intraper-itoneally 30 min before I/R induction. Liver tissues were analyzed for creatinine, alanine ami-notransferase (ALT), aspartate aminotransferase (AST), thiobarbituric acid reactive substances (TBARS), and total thiol (TT) levels.

RESULTS

Compared with the control group, the I/R group presented significantly increased AST, ALT, TBARS, and TT levels. TMZ notably reduced creatinine levels. I/R caused significant liver necrosis, inflammation, and congestion. TMZ and DEX treatments reduced this histopathological damage, with DEX resulting in a more significant reduction in infiltrative areas and vascular congestion. The increase in the expression of caspase-3, Bax, 8-OHdG, C/EBP homologous protein (CHOP), and glucose-regulated protein 78 (GRP78) decreased with the TMZ and DEX treatments. In addition, Bcl-2 positivity decreased both in the TMZ and DEX treatments.

CONCLUSIONS

Both TMZ and DEX have protective effects against liver damage. These effects are likely mediated through the reduction in ERS and apoptosis, with DEX showing slightly superior protective effects compared with TMZ.

Normothermic ex vivo kidney perfusion preserves mitochondrial and graft function after warm ischemia and is further enhanced by AP39

We previously reported that normothermic ex vivo kidney  perfusion (NEVKP) is superior in terms of organ protection compared to static cold storage (SCS), which is still the standard method of organ preservation, but the mechanisms are incompletely understood. We used a large animal kidney autotransplant model to evaluate mitochondrial function during organ preservation and after kidney transplantation, utilizing live cells extracted from fresh kidney tissue. Male porcine kidneys stored under normothermic perfusion showed preserved mitochondrial function and higher ATP levels compared to kidneys stored at 4 °C (SCS). Mitochondrial respiration and ATP levels were further enhanced when AP39, a mitochondria-targeted hydrogen sulfide donor, was administered during warm perfusion. Correspondingly, the combination of NEVKP and AP39 was associated with decreased oxidative stress and inflammation, and with improved graft function after transplantation. In conclusion, our findings suggest that the organ-protective effects of normothermic perfusion are mediated by maintenance of mitochondrial function and enhanced by AP39 administration. Activation of mitochondrial function through the combination of AP39 and normothermic perfusion could represent a new therapeutic strategy for long-term renal preservation.

The renoprotective effects of gallic acid on cisplatin-induced nephrotoxicity through anti-apoptosis, anti-inflammatory effects, and downregulation of lncRNA TUG1

Cisplatin, an antineoplastic drug used in cancer therapy, -induced nephrotoxicity mediated by the production of reactive oxygen species (ROS). Gallic acid (GA) is identified as an antioxidant substance with free radical scavenging properties. This research was designed to examine the ameliorative impact of GA caused by cisplatin-induced nephrotoxicity through apoptosis and long non-coding RNA (lncRNA) Taurine-upregulated gene 1 (TUG1) expression. Thirty-two male Sprague Dawley rats (200 - 220 g) were randomly allocated to four groups: (1) control group; (2) rats treated with cisplatin (7.5 mg/kg, i.p.) on the fourth day; and the two other groups include rats pretreated with GA (20 and 40 mg/kg by gavage) for s7 days and cisplatin (7.5 mg/kg, i.p.) at the fourth day. The rats were anesthetized and sacrificed for collecting samples, 72 h after cisplatin administration. The blood samples were used to investigate biochemical factors and kidney tissue was evaluated for measuring oxidative stress and inflammatory factors and the gene expression of molecular parameters. The results indicated that GA administration increased the B-cell lymphoma-2 (Bcl-2) mRNA and lncRNA TUG1 expression, and reduced Bcl-2-associated x protein (Bax), and caspase-3 expression. Likewise, the TAC level increased, and kidney MDA content decreased by administration of GA. GA also decreased the inflammatory factor levels, including IL-1β and TNF-α. Moreover, GA led to the improvement of kidney dysfunction as evidenced by reducing plasma BUN (blood urea nitrogen) and Cr (creatinine). Taken together, GA could protect the kidney against cisplatin-induced nephrotoxicity through antioxidant, anti-inflammatory, and anti-apoptosis properties and reduction of lncRNA TUG1 expression.

Prolonged warm ischemia time leads to severe renal dysfunction of donation-after-cardiac death kidney grafts

Kidney transplantation with grafts procured after donation-after-cardiac death (DCD) has led to an increase in incidence of delayed graft function (DGF). It is thought that the warm ischemic (WI) insult encountered during DCD procurement is the cause of this finding, although few studies have been designed to definitely demonstrate this causation in a transplantation setting. Here, we use a large animal renal transplantation model to study the effects of prolonged WI during procurement on post-transplantation renal function. Kidneys from 30 kg-Yorkshire pigs were procured following increasing WI times of 0 min (Heart-Beating Donor), 30 min, 60 min, 90 min, and 120 min (n = 3-6 per group) to mimic DCD. Following 8 h of static cold storage and autotransplantation, animals were followed for 7-days. Significant renal dysfunction (SRD), resembling clinical DGF, was defined as the development of oliguria < 500 mL in 24 h from POD3-4 along with POD4 serum potassium > 6.0 mmol/L. Increasing WI times resulted in incremental elevation of post-operative serum creatinine that peaked later. DCD120min grafts had the highest and latest elevation of serum creatinine compared to all groups (POD5: 19.0 ± 1.1 mg/dL, p < 0.05). All surviving animals in this group had POD4 24 h urine output < 500 cc (mean 235 ± 172 mL) and elevated serum potassium (7.2 ± 1.1 mmol/L). Only animals in the DCD120min group fulfilled our criteria of SRD (p = 0.003), and their renal function improved by POD7 with 24 h urine output > 500 mL and POD7 serum potassium < 6.0 mmol/L distinguishing this state from primary non-function. In a transplantation survival model, this work demonstrates that prolonging WI time similar to that which occurs in DCD conditions contributes to the development of SRD that resembles clinical DGF.

Simply Adding Oxygen during Hypothermic Machine Perfusion to Combat the Negative Effects of Ischemia-Reperfusion Injury: Fundamentals and Current Evidence for Kidneys

The use of high-risk renal grafts for transplantation requires optimization of pretransplant preservation and assessment strategies to improve clinical outcomes as well as to decrease organ discard rate. With oxygenation proposed as a resuscitative measure during hypothermic machine preservation, this review provides a critical overview of the fundamentals of active oxygenation during hypothermic machine perfusion, as well as the current preclinical and clinical evidence and suggests different strategies for clinical implementation.

A Pilot Study of Postoperative Animal Welfare as a Guidance Tool in the Development of a Kidney Autotransplantation Model With Extended Warm Ischemia

This pilot study aimed to maintain acceptable animal welfare in the development of a porcine autotransplantation model with severe and incremental renal ischemic injury, a model for usage in future intervention studies. Secondary aims were to develop and test methods to collect blood and urine without the need to restrain or use sedative and avoid transportation to optimize welfare of the pig.

The renoprotective effects of naringin and trimetazidine on renal ischemia/reperfusion injury in rats through inhibition of apoptosis and downregulation of micoRNA-10a

Renal Ischemia-Reperfusion (IR) injury occurs due to circulatory shock and renal transplantation, leading to mortality and morbidity worldwide. The primary purpose of the current study was to evaluate the renoprotective effects of the naringin (NAR) and trimetazidine (TMZ) on IR injury, renal hemodynamics, antioxidant capacity, microRNA-10a, and expression of apoptosis factors. Forty rats were divided into five groups randomly: Sham, IR injury, (TMZ, 5 mg/kg), (NAR pretreatment, 100 mg/kg), and TMZ plus NAR. The sham group underwent the identical surgical procedure as the other groups, except for the application of clamps. After anesthesia, IR injury was induced by 45 min of ischemia, followed by reperfusion for 4 h. Tissue and blood samples were collected for evaluation of renal function, antioxidant activity and, biochemical and molecular parameters. Administration of the NAR, TMZ, and their combination decreased the plasma level of microRNA-10a, caspase-3, and Bcl-2 associated x protein (Bax) mRNA expression, but increased the B- cell lymphoma 2 (Bcl-2) mRNA expression in the kidney tissue. In addition, antioxidant activity, renal blood flow, creatinine clearance (C_Cr), and fractional excretion of sodium (FE_Na) were improved. The NAR, TMZ, and their combination can prevent renal I/R injury through promotion of the level of antioxidant enzymes, as well as decrease of microRNA-10a and anti-apoptosis properties. Our data also suggest that NAR, TMZ, or their combination might be beneficial as potent therapeutic factors against renal IR injury.

Hypercholesterolemia-induced increase in plasma oxidized LDL abrogated pro angiogenic response in kidney grafts

BACKGROUND

Renal transplantation is increasingly associated with the presence of comorbidity factors such as dyslipidemia which could influence the graft outcome. We hypothesized that hypercholesterolemia could affect vascular repair processes and promote post-transplant renal vascular remodeling through the over-expression of the anti-angiogenic thrombospondin-1 interacting with vascular endothelial growth factor-A levels.

METHODS

We tested this hypothesis in vitro, in vivo and in a human cohort using (1) endothelial cells; (2) kidney auto-transplanted pig subjected (n = 5) or not (n = 6) to a diet enriched in cholesterol and (3) a renal transplanted patient cohort (16 patients).

RESULTS

Cells exposed to oxidized LDL showed reduced proliferation and an increased expression of thrombospondin-1. In pigs, 3 months after transplantation of kidney grafts, we observed a deregulation of the hypoxia inducible factor 1a-vascular endothelial growth factor-A axis induced in cholesterol-enriched diet animals concomitant with an overexpression of thrombospondin-1 and a decrease in cortical microvessel density promoting vascular remodeling. In patients, hypercholesterolemia was associated with decreased vascular endothelial growth factor-A plasma levels during early follow up after renal transplantation and increased chronic graft dysfunction.

CONCLUSIONS

These results support a potential mechanism through which a high fat-diet impedes vascular repair in kidney graft and suggest the value of controlling cholesterolemia in recipient even at the early stage of renal transplantation.

MicroRNA-493 targets STMN-1 and promotes hypoxia-induced epithelial cell cycle arrest in G2/M and renal fibrosis

Hypoxia plays an important role in the development of renal fibrosis. G₂/M arrest in renal tubular cells is an important pathway in the development of chronic kidney disease. It is unknown whether hypoxia leads to renal fibrosis via the regulation of G₂/M arrest in renal tubular epithelial cells. For the first time, to our knowledge, we showed that hypoxia induces G₂/M arrest in renal tubular cells leading to renal fibrosis, and microRNAs are involved in this regulation. We compared microRNA expression between hypoxia and normoxia in HK2 cells and found microRNA (miR)-493 to be highly expressed at 24 and 48 h after hypoxia. The overexpression of miR-493 reduced the expression of the cell cycle regulator, Stathmin (STMN)-1, and increased the percentage of G₂/M phase cells and profibrotic factors in HK2 cells. Targeting STMN-1 with short hairpin RNA produced an effect similar to that of miR-493 overexpression. On contrast, the miR-493 inhibitor reversed these effects in vitro. Consistent with these results, miR-493 sponge adeno-associated virus reduced the expression of profibrotic factors and increased STMN-1 in vivo. In summary, these results suggest that the miR-493-STMN-1 pathway contributes to hypoxia-induced tubular epithelial cell G₂/M arrest and renal fibrosis. Abrogating G₂/M arrest and blocking the miR-493-STMN-1 pathway will provide further insight for the development of antifibrosis therapy.-Liu, T., Liu, L., Liu, M., Du, R., Dang, Y., Bai, M., Zhang, L., Ma, F., Yang, X., Ning, X., Sun, S. MicroRNA-493 targets STMN-1 and promotes hypoxia-induced epithelial cell cycle arrest In G₂/M and renal fibrosis.

Effects of Post Ischemia-Reperfusion Treatment with Trimetazidine on Renal Injury in Rats: Insights on Delayed Renal Fibrosis Progression

Even after recovery from acute kidney injury, glomeruli remain vulnerable to further injury by way of interstitial fibrosis. This study is aimed at elucidating the effects of post ischemia-reperfusion (I/R) treatment with trimetazidine on the progression to renal fibrosis as well as short- and intermediate-term aspects. Trimetazidine 3 mg/kg or 0.9% saline was given intraperitoneally once upon reperfusion or daily thereafter for 5 d or 8 w. Renal histologic changes and related signaling proteins were assessed. After 24 h, post I/R treatment with trimetazidine significantly reduced serum blood urea nitrogen and creatinine levels and tubular injury accompanied with upregulation of hypoxia-inducible factor- (HIF-) 1α, vascular endothelial growth factor (VEGF), and Bcl-2 expression. After 5 d, post I/R treatment with trimetazidine reduced renal tubular cell necrosis and apoptosis with upregulation of HIF-1α-VEGF and tissue inhibitors of metalloproteinase activities, attenuation of matrix metalloproteinase activities, and alteration of the ratio of Bax to Bcl-2 levels. After 8 w, however, post I/R treatment with trimetazidine did not modify the progression of renal fibrosis. In conclusion, post I/R treatment with trimetazidine allows ischemic kidneys to regain renal function and structure more rapidly compared to nontreated kidneys, but not enough to resolute renal fibrosis in long-term aspect.

The Optimal PEG for Kidney Preservation: A Preclinical Porcine Study

University of Wisconsin (UW) solution is not optimal for preservation of marginal organs. Polyethylene glycol (PEG) could improve protection. Similarly formulated solutions containing either 15 or 20 g/L PEG 20 kDa or 5, 15 and 30 g/L PEG 35 kDa were tested in vitro on kidney endothelial cells, ex vivo on preserved kidneys, and in vivo in a pig kidney autograft model. In vitro, all PEGs provided superior preservation than UW in terms of cell survival, adenosine triphosphate (ATP) production, and activation of survival pathways. Ex vivo, tissue injury was lower with PEG 20 kDa compared to UW or PEG 35 kDa. In vivo, function recovery was identical between UW and PEG 35 kDa groups, while PEG 20 kDa displayed swifter recovery. At three months, PEG 35 kDa 15 and 30 g/L animals had worse outcomes than UW, while 5 g/L PEG 35 kDa was similar. PEG 20 kDa was superior to both UW and PEG 35 kDa in terms of function and fibrosis development, with low activation of damage pathways. PEG 20 kDa at 15 g/L was superior to 20 g/L. While in vitro models did not discriminate between PEGs, in large animal models of transplantation we showed that PEG 20 kDa offers a higher level of protection than UW and that longer chains such as PEG 35 kDa must be used at low doses, such as found in Institut George Lopez (IGL1, 1g/L).

Prevention of ischemia-reperfusion lung injury during static cold preservation by supplementation of standard preservation solution with HEMO2life® in pig lung transplantation model

We describe the results of adding a new biological agent HEMO₂life^® to a standard preservation solution for hypothermic static lung preservation aiming to improve early functional parameters after lung transplantation. HEMO₂life^® is a natural oxygen carrier extracted from Arenicola marina with high oxygen affinity developed as an additive to standard organ preservation solutions. Standard preservation solution (Perfadex^®) was compared with Perfadex^® associated with HEMO₂life^® and with sham animals after 24 h of hypothermic preservation followed by lung transplantation. During five hours of lung reperfusion, functional parameters and biomarkers expression in serum and in bronchoalveolar lavage fluid (BALF) were measured. After five hours of reperfusion, HEMO₂life^® group led to significant improvement in functional parameters: reduction of graft vascular resistance (p < .05) and increase in graft oxygenation ratio (p < .05). Several ischemia-reperfusion related biomarkers showed positive trends in the HEMO₂life^® group: expression of HMG B1 in serum tended to be lower in comparison (2.1 ± 0.8 vs. 4.6 ± 1.5) with Perfadex^® group, TNF-α and IL-8 in BALF were significantly higher in the two experimental groups compared to control (p < .05). During cold ischemia, expression of HIF1α and histology remained unchanged and similar to control. Supplementation of the Perfadex^® solution by an innovative oxygen carrier HEMO₂life^® during hypothermic static preservation improves early graft function after prolonged cold ischemia in lung transplantation.

Hydrogen sulfide prevents renal ischemia-reperfusion injury in CLAWN miniature swine

BACKGROUND

Hydrogen sulfide (H₂S) has recently been reported to demonstrate both antiinflammatory and cytoprotective effects; however, its efficacy has not been well documented in large animal models. In this study, we examined whether the administration of H₂S offers cytoprotective effects on renal ischemia-reperfusion injury (IRI) in a preclinical miniature swine model.

METHODS

Major histocompatibility complex-inbred, CLAWN miniature swine (n = 9) underwent a right nephrectomy, followed by induction of a 120-min period of warm ischemia via placement of clamps on the left renal artery and vein. Group 1 (n = 3) underwent renal ischemia without H₂S administration. Groups 2 (n = 3) and 3 (n = 3) received Na₂S (prodrug of H₂S) 10 min before reperfusion of the ischemic kidneys followed by a 30-min of Na₂S postreperfusion intravenously (group 2) or selective administration of Na₂S via the left renal artery (group 3). IRI was assessed by kidney biopsies, levels of inflammatory cytokines in sera and kidney tissue.

RESULTS

Animals in group 1 had significantly higher serum creatinine levels compared with animals in groups 2 and 3 (P < 0.01). Histology showed severe tubular damage with TUNEL-positive cells in group 1 on postoperative day 2 compared with mild damage in group 2 and minimal damage in group 3. Furthermore, levels of inflammatory cytokines in both serum (interleukin-6 [IL-6], tumor necrosis factor-α, and high-mobility group box 1) and renal tissue (IL-1 and IL-6) in group 3 were markedly lower than in group 2, suggesting beneficial effects of selective Na₂S administration.

CONCLUSIONS

Na₂S administration, especially via an organ selective approach, appears to potentially offer cytoprotective and antiinflammatory effects following renal IRI.

Eight-Hour Continuous Normothermic Ex Vivo Kidney Perfusion Is a Safe Preservation Technique for Kidney Transplantation: A New Opportunity for the Storage, Assessment, and Repair of Kidney Grafts

BACKGROUND

Hypothermic kidney storage causes preservation injury and is poorly tolerated by renal grafts. We investigated whether static cold storage (SCS) can be safely replaced with a novel technique of pressure-controlled normothermic ex vivo kidney perfusion (NEVKP) in heart-beating donor kidney transplantation.

METHODS

Right kidneys were removed from 30 kg Yorkshire pigs in a model of heart-beating donation and either preserved in cold histidine-tryptophan-ketoglutarate solution for 8 hours (n = 5), or subjected to 8 hours of pressure-controlled NEVKP (n = 5) followed by renal heterotopic autotransplantation.

RESULTS

During NEVKP, physiologic perfusion conditions were maintained with low intrarenal resistance and normal electrolyte and pH parameters. Aspartate aminotransferase and lactate dehydrogenase as injury markers were below the detectable analyzer range (<4 and <100 U/L, respectively). Perfusate lactate concentration decreased from baseline until the end of perfusion (10.38 ± 0.76 mmol/L vs 1.22 ± 0.26 mmol/L; P < 0.001). Posttransplantation, animals transplanted with NEVKP versus SCS grafts demonstrated similar serum creatinine peak levels (NEVKP, 2.0 ± 0.5 vs SCS 2.7 ± 0.7 mg/dL; P = 0.11) and creatinine clearance on day 10 (NEVKP, 65.9 ± 18.8 mL/min vs SCS 61.2 ± 15.6 mL/min; P = 0.74). After 10 days of follow-up, animals transplanted with NEVKP grafts had serum creatinine and blood urea nitrogen values comparable to their basal levels (P = 0.49 and P = 0.59), whereas animals transplanted with SCS grafts had persistently elevated serum creatinine and blood urea nitrogen when compared with basal levels (P = 0.01 and P = 0.03).

CONCLUSIONS

Continuous pressure-controlled NEVKP is feasible and safe in good quality heart-beating donor kidney grafts. It maintains a physiologic environment and excellent graft function ex vivo during preservation without causing graft injury.

Testing Danegaptide Effects on Kidney Function after Ischemia/Reperfusion Injury in a New Porcine Two Week Model

INTRODUCTION

Ischemia/reperfusion injury (I/R-I) is a leading cause of acute kidney injury (AKI) and is associated with increased mortality. Danegaptide is a selective modifier of the gap junction protein connexion 43. It has cytoprotective as well as anti-arrhythmic properties and has been shown to reduce the size of myocardial infarct in pigs. The aim of this study was to investigate the ischemia-protective effect of Danegaptide in a porcine renal I/R-I model with two weeks follow up.

METHODS

Unilateral renal I/R-I was induced in pigs by clamping the left renal artery over a two hour period. The model allowed examination of renal blood flow by magnetic resonance imaging (MRI) and the measurement of single kidney GFR two weeks after injury. Eleven animals were randomized to Danegaptide-infusion while nine animals received placebo. Kidney histology and urinary neutrophil gelatinase-associated lipocalin (NGAL) excretion were included as markers of AKI.

RESULTS

Unilateral kidney I/R-I resulted in an immediate ~50% GFR reduction, associated with a four-fold increase in urinary NGAL-excretion. Fourteen days after I/R-I, the total GFR was ~75% of baseline with a significantly lower GFR in the injured left kidney compared to the right kidney. No differences in GFR were observed between the treated and non-treated animals immediately after I/R-I or at Day 14. Furthermore, no differences were observed in the urinary excretion of NGAL, renal blood flow or other markers of renal function.

CONCLUSIONS

As expected this porcine renal I/R-I model was associated with reduced GFR two weeks after injury. Danegaptide did not improve renal function after I/R-I.

Progression after AKI: Understanding Maladaptive Repair Processes to Predict and Identify Therapeutic Treatments

Recent clinical studies indicate a strong link between AKI and progression of CKD. The increasing prevalence of AKI must compel the nephrology community to consider the long-term ramifications of this syndrome. Considerable gaps in knowledge exist regarding the connection between AKI and CKD. The 13th Acute Dialysis Quality Initiative meeting entitled "Therapeutic Targets of Human Acute Kidney Injury: Harmonizing Human and Experimental Animal Acute Kidney Injury" convened in April of 2014 and assigned a working group to focus on issues related to progression after AKI. This article provides a summary of the key conclusions and recommendations of the group, including an emphasis on terminology related to injury and repair processes for both clinical and preclinical studies, elucidation of pathophysiologic alterations of AKI, identification of potential treatment strategies, identification of patients predisposed to progression, and potential management strategies.

Remote Ischemic Preconditioning May Attenuate Renal Ischemia-Reperfusion Injury in a Porcine Model of Supraceliac Aortic Cross-Clamping

AIM

The effect of remote ischemic preconditioning (RIPC) in decreasing renal ischemia-reperfusion injury (IRI) during a suprarenal aortic cross-clamping was examined in a swine model.

MATERIALS AND METHODS

Four groups of pigs were examined: (a) ischemia-reperfusion (IR) group, renal IRI produced by 30 min of supraceliac aortic cross-clamping; (b) RIPC I group, the same renal IRI following RIPC by brief occlusion of the infrarenal aorta (15 min ischemia and 15 min reperfusion); (c) RIPC II group, the same renal IRI following RIPC by brief occlusion of the infrarenal aorta (3 cycles of 5 min ischemia and 5 min reperfusion); (d) sham group. Renal function was assessed before and after IRI by examining creatinine, neutrophil gelatinase-associated lipocalin (NGAL), TNF-α, malondialdehyde (MDA), cystatin C and C-reactive protein (CRP) from renal vein blood samples at specific time intervals.

RESULTS

Both RIPC groups presented significantly less impaired results compared to the IR group when considering MDA, cystatin C, CRP and creatinine. Between the two RIPC groups, RIPC II presented a better response with regard to CRP, NGAL, TNF-α, MDA and cystatin C.

CONCLUSIONS

Remote IR protocols and mainly repetitive short periods of cycles of IR ameliorate the biochemical kidney effects of IRI in a model of suprarenal aortic aneurysm repair.

Strategies to optimize kidney recovery and preservation in transplantation: specific aspects in pediatric transplantation

In renal transplantation, live donor kidney grafts are associated with optimum success rates due to the shorter period of ischemia during the surgical procedure. The current shortage of donor organs for adult patients has caused a shift towards deceased donors, often with co-morbidity factors, whose organs are more sensitive to ischemia-reperfusion injury, which is unavoidable during transplantation. Donor management is pivotal to kidney graft survival through the control of the ischemia-reperfusion sequence, which is known to stimulate numerous deleterious or regenerative pathways. Although the key role of endothelial cells has been established, the complexity of the injury, associated with stimulation of different cell signaling pathways, such as unfolded protein response and cell death, prevents the definition of a unique therapeutic target. Preclinical transplant models in large animals are necessary to establish relationships and kinetics and have already contributed to the improvement of organ preservation. Therapeutic strategies using mesenchymal stem cells to induce allograft tolerance are promising advances in the treatment of the pediatric recipient in terms of reducing/withdrawing immunosuppressive therapy. In this review we focus on the different donor management strategies in kidney graft conditioning and on graft preservation consequences by highlighting the role of endothelial cells. We also propose strategies for preventing ischemia-reperfusion, such as cell therapy.

Effects of trimetazidine on the Akt/eNOS signaling pathway and oxidative stress in an in vivo rat model of renal ischemia-reperfusion

Renal ischemia reperfusion (I/R) injury, which occurs during renal surgery or transplantation, is the major cause of acute renal failure. Trimetazidine (TMZ), an anti-ischemic drug, protects kidney against the deleterious effects of I/R. However its protective mechanism remains unclear. The aim of this study is to examine the relevance of Akt, endothelial nitric oxide synthase (eNOS), and hypoxia inducible factor-1α (HIF-1α) on TMZ induced protection of kidneys against I/R injury. Wistar rats were subjected to 60 min of warm renal ischemia followed by 120 min of reperfusion, or to intraperitoneal injection of TMZ (3 mg/kg) 30 min before ischemia. In sham operated group renal pedicles were only dissected. Compared to I/R, TMZ treatment decreased lactate dehydrogenase (845 ± 13 vs. 1028 ± 30 U/L). In addition, creatinine clearance and sodium reabsorption rates reached 105 ± 12 versus 31 ± 11 μL/min/g kidney weight and 95 ± 1 versus 68 ± 5%, respectively. Besides, we noted a decrease in malondialdehyde concentration (0.33 ± 0.01 vs. 0.59 ± 0.03 nmol/mg of protein) and an increase in glutathione concentration (2.6 ± 0.2 vs. 0.93 ± 0.16 µg GSH/mg of protein), glutathione peroxidase (95 ± 4 vs. 61 ± 3 µg GSH/min/mg of protein), and superoxide dismutase (25 ± 3 vs. 11 ± 2 U/mg of protein) and catalase (91 ± 12 vs. 38 ± 9 μmol/min/mg of protein) activities. Parallely, we noted a significant increase in p-Akt, eNOS, nitrite and nitrate (18 ± 2 vs. 8 ± 0.1 pomL/mg of protein), HIF-1α (333 ± 48 vs. 177 ± 14 µg/mg of protein) and heme oxygenase-1 (HO-1) levels regarding I/R. TMZ treatment improves renal tolerance to warm I/R. Such protection implicates an activation of Akt/eNOS signaling pathway, HIF-1α stabilization and HO-1 activation.

Trimetazidine Decreases Risk of Contrast-Induced Nephropathy in Patients With Chronic Kidney Disease

Objectives:

We sought to synthesize and analyze the available data from randomized controlled trials (RCTs) for trimetazidine (TMZ) in the prevention of contrast-induced nephropathy (CIN).

Background:

Contrast-induced nephropathy after coronary angiography is associated with poor outcomes. Trimetazidine is an anti-ischemic drug that might reduce incidence of CIN, but current data are inconclusive.

Methods:

We searched MEDLINE/PubMed, EMBASE, Scopus, Cochrane Library, Web of Science, and ScienceDirect electronic databases for RCTs comparing intravenous hydration with normal saline (NS) and/or N-acetyl cysteine (NAC) versus TMZ plus NS ± NAC for prevention of CIN. We used RevMan 5.2 for statistical analysis with the fixed effects model.

Results:

Of the 808 studies, 3 RCTs met criteria with 290 patients in the TMZ plus NS ± NAC group and 292 patients in the NS ± NAC group. The mean age of patients was 59.5 years, and baseline serum creatinine ranged from 1.3 to 2 mg/dL. Trimetazidine significantly reduced the incidence of CIN by 11% (risk difference 0.11; 95% confidence interval, 0.16-0.06; P < .01). There was no significant heterogeneity between the studies (I2 statistic = 0). The number needed to treat to prevent 1 episode of CIN was 9.

Conclusions:

The addition of TMZ to NS ± NAC significantly decreased the incidence of CIN in patients undergoing coronary angiography. In conclusion, TMZ could be considered as a potential tool for prevention of CIN in patients with renal dysfunction.

Amniotic fluid-derived mesenchymal stem cells prevent fibrosis and preserve renal function in a preclinical porcine model of kidney transplantation

It is well known that ischemia/reperfusion injuries strongly affect the success of human organ transplantation. Development of interstitial fibrosis and tubular atrophy is the main deleterious phenomenon involved. Stem cells are a promising therapeutic tool already validated in various ischemic diseases. Amniotic fluid-derived mesenchymal stem cells (af-MSCs), a subpopulation of multipotent cells identified in amniotic fluid, are known to secrete growth factors and anti-inflammatory cytokines. In addition, these cells are easy to collect, present higher proliferation and self-renewal rates compared with other adult stem cells (ASCs), and are suitable for banking. Consequently, af-MSCs represent a promising source of stem cells for regenerative therapies in humans. To determine the efficiency and the safety of af-MSC infusion in a preclinical porcine model of renal autotransplantation, we injected autologous af-MSCs in the renal artery 6 days after transplantation. The af-MSC injection improved glomerular and tubular functions, leading to full renal function recovery and abrogated fibrosis development at 3 months. The strong proof of concept generated by this translational porcine model is a first step toward evaluation of af-MSC-based therapies in human kidney transplantation.

The identification of novel potential injury mechanisms and candidate biomarkers in renal allograft rejection by quantitative proteomics

Early transplant dysfunction and failure because of immunological and nonimmunological factors still presents a significant clinical problem for transplant recipients. A critical unmet need is the noninvasive detection and prediction of immune injury such that acute injury can be reversed by proactive immunosuppression titration. In this study, we used iTRAQ -based proteomic discovery and targeted ELISA validation to discover and validate candidate urine protein biomarkers from 262 renal allograft recipients with biopsy-confirmed allograft injury. Urine samples were randomly split into a training set of 108 patients and an independent validation set of 154 patients, which comprised the clinical biopsy-confirmed phenotypes of acute rejection (AR) (n = 74), stable graft (STA) (n = 74), chronic allograft injury (CAI) (n = 58), BK virus nephritis (BKVN) (n = 38), nephrotic syndrome (NS) (n = 8), and healthy, normal control (HC) (n = 10). A total of 389 proteins were measured that displayed differential abundances across urine specimens of the injury types (p < 0.05) with a significant finding that SUMO2 (small ubiquitin-related modifier 2) was identified as a "hub" protein for graft injury irrespective of causation. Sixty-nine urine proteins had differences in abundance (p < 0.01) in AR compared with stable graft, of which 12 proteins were up-regulated in AR with a mean fold increase of 2.8. Nine urine proteins were highly specific for AR because of their significant differences (p < 0.01; fold increase >1.5) from all other transplant categories (HLA class II protein HLA-DRB1, KRT14, HIST1H4B, FGG, ACTB, FGB, FGA, KRT7, DPP4). Increased levels of three of these proteins, fibrinogen beta (FGB; p = 0.04), fibrinogen gamma (FGG; p = 0.03), and HLA DRB1 (p = 0.003) were validated by ELISA in AR using an independent sample set. The fibrinogen proteins further segregated AR from BK virus nephritis (FGB p = 0.03, FGG p = 0.02), a finding that supports the utility of monitoring these urinary proteins for the specific and sensitive noninvasive diagnosis of acute renal allograft rejection.

Role of warm ischemia on innate and adaptive responses in a preclinical renal auto-transplanted porcine model

Background

Deceased after cardiac arrest donor are an additional source of kidney graft to overcome graft shortage. Deciphering the respective role of renal warm and cold ischemia is of pivotal interest in the transplantation process.

Methods

Using a preclinical pig model of renal auto-transplantation, we investigated the consequences of warm and cold ischemia on early innate and adaptive responses as well as graft outcome. Kidneys were subjected to either 60 min-warm ischemia (WI) or auto-transplanted after cold storage for 24 h at 4°C (CS), or both conditions combined (WI + CS). Renal function, immune response and cytokine expression, oxidative stress and cell death were investigated at 3 h, 3 and 7 days (H3, D3 and D7) after reperfusion. At 3 months, we focused on cell infiltration and tissue remodelling.

Results

WI + CS induced a delayed graft function linked to higher tubular damage. Innate response occurred at D3 associated to a pro-oxidative milieu with a level dependent on the severity of ischemic injury whereas adaptive immune response occurred only at D7 mainly due to CS injuries and aggravated by WI. Graft cellular death was an early event detected at H3 and seems to be one of the first ischemia reperfusion injuries. These early injuries affect graft outcome on renal function, cells infiltration and fibrosis development.

Conclusions

The results indicate that the severe ischemic insult found in kidneys from deceased after cardiac arrest donor affects kidney outcome and promotes an uncontrolled deleterious innate and adaptive response not inhibited 3 months after reperfusion.

Attenuation of endoplasmic reticulum stress and mitochondrial injury in kidney with ischemic postconditioning application and trimetazidine treatment

Background

Endoplasmic reticulum (ER) and mitochondria have been implicated in the pathology of renal ischemia/reperfusion (I/R). In the present study, we investigated whether the use of ischemic postconditioning (IPostC) and trimetazidine (TMZ) separately or combined could reduce ER stress and mitochondria damage after renal ischemia.

Methods

Kidneys of Wistar rats were subjected to 60-min of warm ischemia followed by 120-min of reperfusion (I/R group, n = 6), or to 6 cycles of ischemia/reperfusion (10-s each cycle) just after 60-min of warm ischemia (IPostC group, n = 6), or to i.p. injection of TMZ (3 mg/kg) 30-min before ischemia (TMZ group, n = 6), or to the combination of both treatments (IPostC+TMZ group, n = 6). The results of these experimental groups were compared to those of a sham-operated group in which rat renal pedicles were only dissected. Sodium reabsorption rate, creatinine clearance lactate deshydrogenase (LDH) activity in plasma, and concentration of malonedialdehyde (MDA) in tissue were determined. In addition, Western blot analysis was performed to identify the amounts of cytochrome c, c-JunNH2-terminal kinase (JNK), voltage-dependent anion channel (VDAC), glycogen synthase kinase 3-beta (GSK3-β), and ER stress parameters.

Results

IPostC or/and TMZ significantly decreased cytolysis, oxidative stress and improved renal function in comparison to I/R group. IPostC but not TMZ significantly attenuated ER stress parameters versus I/R group. Indeed, it down-regulated the glucose-regulated protein 78 (GRP78), the activating transcription factor 4 (ATF4), the RNA activated protein kinase (PKR)-like ER kinas (PERK), the X box binding protein-1 (XBP-1) and the caspase12 protein levels. TMZ treatment significantly augmented GSK3-β phosphorylation and reduced levels of cytochrome c and VDAC phosphorylation in comparison to IPostC application. The combination of both treatments gave a synergetic effect. It significantly improved the survival rate, attenuated cytolysis, oxidative stress and improved renal function.

Conclusion

This study revealed that IPostC protects kidney from I/R injury by suppressing ER stress while the beneficial effects of TMZ are mediated by mitochondria protection. The combination of both treatments ameliorated functional recovery.

Comparative study between trimetazidine and ice slush hypothermia in protection against renal ischemia/reperfusion injury in a porcine model

PURPOSE

The aim of the study was to compare the effects of renal ice slush hypothermia and the use of trimetazidine in the protection against ischemia/reperfusion (I/R) injury.

MATERIALS AND METHODS

Fifteen farm pigs were submitted to left kidney ischemia and right nephrectomy during the same procedure. Animals were divided into three groups. Group 1 was submitted to warm ischemia; Group 2 was submitted to cold ischemia with ice slush; and Group 3 received trimetazidine 20 mg one day and 4 hours before surgery. Ischemia time was 120 minutes in all three groups. Serum creatinine (SCr) and plasma iohexol clearance (CLioh) were measured before surgery and on postoperative days (PODs) 1,3,7, and 14. Semi-quantitative analyses of histological alterations were performed by a pathologist. A p value of < 0.05 was considered significant.

RESULTS

All groups showed elevation of serum creatinine in the first week. Serum creatinine was higher in Group 3 in the first and third postoperative days (Mean Cr: 5.5 and 8.1 respectively). Group 2 showed a lower increase in creatinine and a lower decrease in iohexol clearance than the others. Renal function stabilized in the fourteenth POD in all three groups. Analyses of histological alterations did not reach statistical significance between groups.

CONCLUSION

Trimetazidine did not show protection against renal I/R injury in comparison to warm ischemia or hypothermia in a porcine model submitted to 120 minutes of renal ischemia.

Renal tubulointerstitial hypoxia: cause and consequence of kidney dysfunction

1. Intrarenal oxygen availability is the balance between supply, mainly dependent on renal blood flow, and demand, determined by the basal metabolic demand and the energy-requiring tubular electrolyte transport. Renal blood flow is maintained within close limits in order to sustain stable glomerular filtration, so increased intrarenal oxygen consumption is likely to cause tissue hypoxia. 2. The increased oxygen consumption is closely linked to increased oxidative stress, which increases mitochondrial oxygen usage and reduces tubular electrolyte transport efficiency, with both contributing to increased total oxygen consumption. 3. Tubulointerstitial hypoxia stimulates the production of collagen I and α-smooth muscle actin, indicators of increased fibrogenesis. Furthermore, the hypoxic environment induces epithelial-mesenchymal transdifferentiation and aggravates fibrosis, which results in reduced peritubular blood perfusion and oxygen delivery due to capillary rarefaction. 4. Increased oxygen consumption, capillary rarefaction and increased diffusion distance due to the increased fibrosis per se further aggravate the interstitial hypoxia. 5. Recently, it has been demonstrated that hypoxia simulates the infiltration and maturation of immune cells, which provides an explanation for the general inflammation commonly associated with the progression of chronic kidney disease. 6. Therapies targeting interstitial hypoxia could potentially reduce the progression of chronic renal failure in millions of patients who are otherwise likely to eventually present with fully developed end-stage renal disease.

Gender difference and sex hormone production in rodent renal ischemia reperfusion injury and repair

BACKGROUND

Several lines of evidence suggest a protective effect of female sex hormones in several organs subjected to ischemia-reperfusion injury. The aim of the study was to investigate sex hormone production in male rats after a renal ischemia-reperfusion sequence and analyze the influence of gender differences on tissue remodelling during the recovery process.

METHOD

Age-matched sexually mature male and female rats were subjected to 60 min of renal unilateral ischemia by pedicle clamping with contralateral nephrectomy and followed for 1 or 5 days after reperfusion. Plasma creatinine, systemic testosterone, progesterone and estradiol levels were determined. Tubular injury, cell proliferation and inflammation, were evaluated as well as proliferating cell nuclear antigen, vimentin and translocator protein (TSPO) expressions by immunohistochemistry.

RESULTS

After 1 and 5 days of reperfusion, plasma creatinine was significantly higher in males than in females, supporting the high mortality in this group. After reperfusion, plasma testosterone levels decreased whereas estradiol significantly increased in male rats. Alterations of renal function, associated with tubular injury and inflammation persisted during the 5 days post-ischemia-reperfusion, and a significant improvement was observed in females at 5 days of reperfusion. Proliferating cell nuclear antigen and vimentin expression were upregulated in kidneys from males and attenuated in females, in parallel to injury development. TSPO expression was transiently increased in proximal tubules in male rats.

CONCLUSIONS

After ischemia, renal function recovery and tissue injury is gender-dependent. These differences are associated with a modulation of sex hormone production and a modification of tissue remodeling and proliferative cell processes.

Plexiform lesions in pulmonary arterial hypertension composition, architecture, and microenvironment

Pulmonary arterial hypertension (PAH) is a debilitating disease with a high mortality rate. A hallmark of PAH is plexiform lesions (PLs), complex vascular formations originating from remodeled pulmonary arteries. The development and significance of these lesions have been debated and are not yet fully understood. Some features of PLs resemble neoplastic disorders, and there is a striking resemblance to glomeruloid-like lesions (GLLs) in glioblastomas. To further elucidate PLs, we used in situ methods, such as (fluorescent) IHC staining, three-dimensional reconstruction, and laser microdissection, followed by mRNA expression analysis. We generated compartment-specific expression patterns in the lungs of 25 patients (11 with PAH associated with systemic shunts, 6 with idiopathic PAH, and 8 controls) and GLLs from 5 glioblastomas. PLs consisted of vascular channels lined by a continuously proliferating endothelium and backed by a uniform myogenic interstitium. They also showed up-regulation of remodeling-associated genes, such as HIF1a, TGF-β1, VEGF-α, VEGFR-1/-2, Ang-1, Tie-2, and THBS1, but also of cKIT and sprouting-associated markers, such as NOTCH and matrix metalloproteinases. The cellular composition and signaling seen in GLLs in neural neoplasms differed significantly from those in PLs. In conclusion, PLs show a distinct cellular composition and microenvironment, which contribute to the plexiform phenotype and set them apart from other processes of vascular remodeling in patients with PAH. Neoplastic models of angiogenesis seem to be of limited use in further study of plexiform vasculopathy.

Contribution of large pig for renal ischemia-reperfusion and transplantation studies: the preclinical model

Animal experimentation is necessary to characterize human diseases and design adequate therapeutic interventions. In renal transplantation research, the limited number of in vitro models involves a crucial role for in vivo models and particularly for the porcine model. Pig and human kidneys are anatomically similar (characterized by multilobular structure in contrast to rodent and dog kidneys unilobular). The human proximity of porcine physiology and immune systems provides a basic knowledge of graft recovery and inflammatory physiopathology through in vivo studies. In addition, pig large body size allows surgical procedures similar to humans, repeated collections of peripheral blood or renal biopsies making pigs ideal for medical training and for the assessment of preclinical technologies. However, its size is also its main drawback implying expensive housing. Nevertheless, pig models are relevant alternatives to primate models, offering promising perspectives with developments of transgenic modulation and marginal donor models facilitating data extrapolation to human conditions.

Analysis of machine perfusion benefits in kidney grafts: a preclinical study

Background

Machine perfusion (MP) has potential benefits for marginal organs such as from deceased from cardiac death donors (DCD). However, there is still no consensus on MP benefits. We aimed to determine machine perfusion benefits on kidney grafts.

Methods

We evaluated kidney grafts preserved in ViaspanUW or KPS solutions either by CS or MP, in a DCD pig model (60 min warm ischemia + 24 h hypothermic preservation). Endpoints were: function recovery, quality of function during follow up (3 month), inflammation, fibrosis, animal survival.

Results

ViaspanUW-CS animals did not recover function, while in other groups early follow up showed similar values for kidney function. Alanine peptidase and β-NAG activities in the urine were higher in CS than in MP groups. Oxydative stress was lower in KPS-MP animals. Histology was improved by MP over CS. Survival was 0% in ViaspanUW-CS and 60% in other groups. Chronic inflammation, epithelial-to-mesenchymal transition and fibrosis were lowest in KPS-MP, followed by KPS-CS and ViaspanUW-MP.

Conclusions

With ViaspanUW, effects of MP are obvious as only MP kidney recovered function and allowed survival. With KPS, the benefits of MP over CS are not directly obvious in the early follow up period and only histological analysis, urinary tubular enzymes and red/ox status was discriminating. Chronic follow-up was more conclusive, with a clear superiority of MP over CS, independently of the solution used. KPS was proven superior to ViaspanUW in each preservation method in terms of function and outcome. In our pre-clinical animal model of DCD transplantation, MP offers critical benefits.

Effect of polyethylene glycol-based preservation solutions on graft injury in experimental kidney transplantation

Background

New preservation solutions are emerging, of various ionic compositions and with hydroxyethyl starch replaced by polymers such as polyethylene glycols (PEGs), offering the potential for ‘immunocamouflage’. This experimental study investigated which of three clinically available preservation protocols offered the best graft protection, based on epithelial-to-mesenchymal transition (EMT) and fibrosis.

Methods

Kidneys were preserved for 24 h at 4 °C with University of Wisconsin solution (UW) as standard, compared with solutions containing either 1 g/l PEG 35 kDa (Institute Georges Lopez solution, IGL) or 30g/l PEG 20 kDa (solution de conservation des organes et des tissus, SCOT). Animals were followed for up to 3 months and development of EMT, tubular atrophy and fibrosis was evaluated in comparison with sham-operated animals.

Results

Functional recovery was better in the SCOT group compared with the other groups. Chronic fibrosis, EMT and inflammation were observed in the UW and IGL groups, but limited in the SCOT group. Levels of profibrosis markers such as transforming growth factor β1, plasminogen activator inhibitor 1 and connective tissue growth factor were increased in IGL and UW groups compared with the SCOT group. Hypoxia-inducible factor (HIF) 1α and 2α expression was increased at 3 months in grafts preserved in UW and IGL, but detected transiently on day 14 when SCOT was used. Expression of HIF-regulated genes vascular endothelial growth factor and erythropoietin was increased in UW and IGL groups.

Conclusion

The choice of colloid and ionic content is paramount in providing long-term protection against chronic graft injury after renal transplantation. Preservation solutions based on PEGs may optimize graft quality.

Thrombin inhibition during kidney ischemia-reperfusion reduces chronic graft inflammation and tubular atrophy

BACKGROUND

Ischemia-reperfusion injury (IRI) is an unavoidable component of transplantation and correlates with delayed graft function, acute rejection, chronic fibrosis, and graft loss. Currently, new donor pools are considered to alleviate pressure on waiting lists, such as deceased after cardiac death donors (DCD) and extended criteria donors. Because these organs are particularly sensitive to IRI, there is a need for novel preservation paradigms. We assessed the effect of anticoagulation therapy during graft preservation on IRI and graft outcome.

METHODS

In a large white autotransplanted pig model, kidneys underwent warm ischemia for 60 min, mimicking DCD, then were preserved for 24 hr at 4°C, in University of Wisconsin solution. Animals were followed up 3 months, functional, histologic, and molecular parameters were assessed. In treated groups, antithrombin was added to collection and preservation protocols.

RESULTS

Treatment improved chronic graft function, reduced tubular atrophy, and substantially increased animal survival. Quantitative polymerase chain reaction analysis determined that markers of inflammation, such as interferon-[gamma], tumor necrosis factor-[alpha], interleukin (IL)-2, -1Rn, and -10, were significantly reduced in treated grafts. Histologic analysis revealed a lowering of CD3+ invasion. P selectin and C3 mRNA expressions were reduced in treated groups, indicative of lowered complement production and endothelial cell activation. Vascular endothelium growth factor protein expression was up-regulated, suggesting vascular network remodeling.

CONCLUSION

Inhibition of thrombin during preservation of DCD graft preserved renal integrity and function, protecting against chronic inflammation and tissue damage. Thus, coagulation seems to be a critical target for the development of therapeutic strategies to improve kidney quality for transplantation.

Hypoxia inducible factor-1α accumulation in steatotic liver preservation: Role of nitric oxide

AIM: To examine the relevance of hypoxia inducible factor (HIF-1) and nitric oxide (NO) on the preservation of fatty liver against cold ischemia-reperfusion injury (IRI).

METHODS: We used an isolated perfused rat liver model and we evaluated HIF-1α in steatotic and non-steatotic livers preserved for 24 h at 4°C in University of Wisconsin and IGL-1 solutions, and then subjected to 2 h of normothermic reperfusion. After normoxic reperfusion, liver enzymes, bile production, bromosulfophthalein clearance, as well as HIF-1α and NO [endothelial NO synthase (eNOS) activity and nitrites/nitrates] were also measured. Other factors associated with the higher susceptibility of steatotic livers to IRI, such as mitochondrial damage and vascular resistance were evaluated.

RESULTS: A significant increase in HIF-1α was found in steatotic and non-steatotic livers preserved in IGL-1 after cold storage. Livers preserved in IGL-1 showed a significant attenuation of liver injury and improvement in liver function parameters. These benefits were enhanced by the addition of trimetazidine (an anti-ischemic drug), which induces NO and eNOS activation, to IGL-1 solution. In normoxic reperfusion, the presence of NO favors HIF-1α accumulation, promoting also the activation of other cytoprotective genes, such as heme-oxygenase-1.

CONCLUSION: We found evidence for the role of the HIF-1α/NO system in fatty liver preservation, especially when IGL-1 solution is used.

Pharmacological strategies against cold ischemia reperfusion injury

IMPORTANCE OF THE FIELD

Good organ preservation is a determinant of graft outcome after revascularization. The necessity of increasing the quality of organ preservation, as well as of extending cold storage time, has made it necessary to consider the use of pharmacological additives.

AREAS COVERED IN THIS REVIEW

The complex physiopathology of cold-ischemia-reperfusion (I/R) injury--and in particular cell death, mitochondrial injury and endoplasmic reticulum stress--are reviewed. Basic principles of the formulation of the different preservation solutions are discussed.

WHAT THE READER WILL GAIN

Current strategies and new trends in static organ preservation using additives such as trimetazidine, polyethylene glycols, melatonin, trophic factors and endothelin antagonists in solution are presented and discussed. The benefits and mechanisms responsible for enhancing organ protection against I/R injury are also discussed. Graft preservation was substantially improved when additives were added to the preservation solutions.

TAKE HOME MESSAGE

Enrichment of preservation solutions by additives is clinically useful only for short periods. For longer periods of cold ischemia, the use of such additives becomes insufficient because graft function deteriorates as a result of ischemia. In such conditions, the preservation strategy should be changed by the use of machine perfusion in normothermic conditions.

Anti-thrombin therapy during warm ischemia and cold preservation prevents chronic kidney graft fibrosis in a DCD model

Ischemia reperfusion injury (IRI) is pivotal for renal fibrosis development via peritubular capillaries injury. Coagulation represents a key mechanism involved in this process. Melagatran (M), a thrombin inhibitor, was evaluated in an autotransplanted kidney model, using Large White pigs. To mimic deceased after cardiac death donor conditions, kidneys underwent warm ischemia (WI) for 60 min before cold preservation for 24 h in University of Wisconsin solution. Treatment with M before WI and/or in the preservation solution drastically improved survival at 3 months, reduced renal dysfunction related to a critical reduction in interstitial fibrosis, measured by Sirius Red staining. Tissue analysis revealed reduced expression of transforming growth factor-beta (TGF-beta) and activation level of its effectors phospho-Smad3, Smad4 and connective tissue growth factor (CTGF) after M treatment. Fibrinolysis activation was also observed, evidenced by downregulation of PAI-1 protein and gene expression. In addition, M reduced S100A4 expression and vimentin staining, which are markers for epithelial mesenchymal transition, a major pathway to chronic kidney fibrosis. Finally, expression of oxidative stress markers Nox2 and iNOS was reduced. We conclude that inhibition of thrombin is an effective therapy against IRI that reduces chronic graft fibrosis, with a significantly positive effect on survival.

Influence of nephron mass and a phosphorylated 38 mitogen-activated protein kinase inhibitor on the development of early and long-term injury after renal warm ischaemia

BACKGROUND

Renal ischaemia is accompanied by acute and chronic complications. Tumour necrosis factor (TNF) alpha production via p38 mitogen-activated protein kinase (MAPK) is one of the pivotal mechanisms linking ischaemia to inflammation and could be a therapeutic target. FR167653 (FR), an inhibitor of p38 MAPK and TNF-alpha production, may ameliorate renal damage through its effects on TNF-alpha.

METHODS

Warm ischaemia (WI) was induced in male pigs by bilateral clamping of the renal pedicle for 60 min or unilateral renal clamping after contralateral nephrectomy. FR was administered before and during WI, and continuously for 3 h during reperfusion in pigs exposed to the same WI conditions. Experimental groups were compared with sham-operated pigs and those subjected to unilateral nephrectomy without renal ischaemia. Renal function, fibrosis and inflammation were evaluated, and expression of monocyte chemoattractant protein 1, transforming growth factor beta and TNF-alpha was determined after 12 weeks.

RESULTS

FR significantly reduced renal failure in groups subjected to unilateral nephrectomy and bilateral renal ischaemia. Proteinuria was significantly reduced, and inflammation and expression of proinjury proteins were diminished, accompanied by a reduction in renal fibrosis.

CONCLUSION

Control of TNF-alpha production and activity prevents renal damage after prolonged WI.

FR167653 improves renal recovery and decreases inflammation and fibrosis after renal ischemia reperfusion injury

OBJECTIVE

Acute tubular necrosis (ATN) secondary to induced warm ischemia (WI) results in inflammatory and delayed fibrotic processes and remains a common clinical problem with serious consequences. Because tumor necrosis factor-alpha (TNF-alpha) is a prominent proinflammatory factor implicated in the pathophysiology of acute renal ischemia reperfusion injury (IRI), we hypothesized that FR167653 (FR), a potent inhibitor of TNF-alpha and interleukin-1beta production, may reduce IRI.

METHODS

IRI was induced in male pigs by bilateral clamping of the renal pedicle for 90 minutes (WI90), or unilateral renal clamping (90 minutes) after contralateral nephrectomy (1/2Nx90), or unilateral renal clamping without contralateral nephrectomy (WIuni90). FR was administered intravenously 60 minutes before WI (1 mg/kg/h), during WI, and continuously for 3 hours (1 mg/kg/h) during reperfusion in treated groups (FRWI90, FR1/2Nx90, or FRWIuni90). Blood and urine samples were collected between day 1 and 3 months after reperfusion for assessment of renal function. Kidneys were excised and renal tissues were collected at 3 months for morphologic and inflammation evaluation and protein analysis. Experimental groups were compared with sham operated (control) and heminephrectomized (Unif) groups without renal ischemia.

RESULTS

Three WI90 animals (43%) and five 1/2Nx90 (70%) were euthanized and necropsied at day 7 because of no urine production or poor conditions. Mortality was significantly improved after FR treatment. Survival was 100% in the control, Unif, WIuni90, and FR groups. In Unif groups, FR significantly reduced renal failure and bilateral renal ischemia (P < .05). At 3 months, proteinuria was significantly reduced in FR-treated groups (P < .01). Inflammatory cells count was also dramatically diminished in FR-treated pigs (P < .01 for CD3-positive cells). The second aspect of transient ischemia is the fibrotic process determined at 3 months. FR treatment was characterized by a reduction of renal fibrosis, particularly in Unif groups. TNF-alpha protein expression was diminished in FR-treated groups.

CONCLUSION

This is the first evidence that FR reduced the early and long-term effect of WI in the severe ischemia model. This effect was particularly marked against fibrosis and inflammation, which would contribute to deterioration of a patient's renal function.

Identifying compartment-specific non-HLA targets after renal transplantation by integrating transcriptome and "antibodyome" measures

We have conducted an integrative genomics analysis of serological responses to non-HLA targets after renal transplantation, with the aim of identifying the tissue specificity and types of immunogenic non-HLA antigenic targets after transplantation. Posttransplant antibody responses were measured by paired comparative analysis of pretransplant and posttransplant serum samples from 18 pediatric renal transplant recipients, measured against 5,056 unique protein targets on the ProtoArray platform. The specificity of antibody responses were measured against gene expression levels specific to the kidney, and 2 other randomly selected organs (heart and pancreas), by integrated genomics, employing the mapping of transcription and ProtoArray platform measures, using AILUN. The likelihood of posttransplant non-HLA targets being recognized preferentially in any of 7 microdissected kidney compartments was also examined. In addition to HLA targets, non-HLA immune responses, including anti-MICA antibodies, were detected against kidney compartment-specific antigens, with highest posttransplant recognition for renal pelvis and cortex specific antigens. The compartment specificity of selected antibodies was confirmed by IHC. In conclusion, this study provides an immunogenic and anatomic roadmap of the most likely non-HLA antigens that can generate serological responses after renal transplantation. Correlation of the most significant non-HLA antibody responses with transplant health and dysfunction are currently underway.

Trimetazidine reduces early and long-term effects of experimental renal warm ischemia: a dose effect study

OBJECTIVE

Renal ischemia reperfusion (IR) injury (IRI) is an important mechanism of acute renal failure (ARF) and a crucial factor of tissue damage during vascular surgery. IR may lead to tissue destruction and influence the early and long-term outcome of organs. The anti-anginal medication trimetazidine (TMZ) is a drug, the protective effects of which have been already assessed during cold preservation and warm ischemia (WI). The objective of this dose-effect study was to assess the role of TMZ in severe renal WI model.

MATERIALS AND METHODS

We have used an established WI pig kidney model associated with a uninephrectomy condition and studied the dose-dependent role of TMZ (1, 5, and 10 mg/Kg, i.v. for 24 hours before WI) against deleterious effects of WI (60 minutes of WI followed by reperfusion) compared with sham-operated (control) and uninephrectomized animals (unif). Direct effect of TMZ was determined using different variables: renal function (creatinine clearance; C(cr)) and indirectly, the consequences on inflammation (cells infiltration), rate of apoptosis, fibrosis development, and renal epithelial cells change into myofibroblast, which defined epithelial to mesenchymal transition (alpha-smooth muscle actin [alpha-SMA] and vimentin expression).

RESULTS

TMZ (5 or 10 mg/Kg) significantly increased C(cr) and reduced the inflammatory response prevalent in ischemic kidney injury and rate of apoptosis expression. In addition, the limitation of initial IRI was correlated with an earlier and greater expression of hypoxia-inducible transcription factor-1alpha (HIF-1alpha), which is a hypoxia marker during kidney regeneration. A reduction of the tubulointerstitial development of fibrosis and a limitation of the alpha-smooth muscle actin expression (alpha-SMA) was observed with TMZ treatment. At 3 months, vimentin expression was increased in WI groups without TMZ or low TMZ dose treatment compared with 5 or 10 mg/Kg treated groups.

CONCLUSION

Collectively, these data suggest that TMZ made the warm ischemic kidneys more resistant to the deleterious impact of a single episode of IR and could have a role in preserving the ischemic kidney from long-term damage.

Novel pharmacological approaches to the treatment of renal ischemia-reperfusion injury: a comprehensive review

Renal ischemia-reperfusion (I-R) contributes to the development of ischemic acute renal failure (ARF). Multi-factorial processes are involved in the development and progression of renal I-R injury with the generation of reactive oxygen species, nitric oxide and peroxynitrite, and the decline of antioxidant protection playing major roles, leading to dysfunction, injury, and death of the cells of the kidney. Renal inflammation, involving cytokine/adhesion molecule cascades with recruitment, activation, and diapedesis of circulating leukocytes is also implicated. Clinically, renal I-R occurs in a variety of medical and surgical settings and is responsible for the development of acute tubular necrosis (a characteristic feature of ischemic ARF), e.g., in renal transplantation where I-R of the kidney directly influences graft and patient survival. The cellular mechanisms involved in the development of renal I-R injury have been targeted by several pharmacological interventions. However, although showing promise in experimental models of renal I-R injury and ischemic ARF, they have not proved successful in the clinical setting (e.g., atrial natriuretic peptide, low-dose dopamine). This review highlights recent pharmacological developments, which have shown particular promise against experimental renal I-R injury and ischemic ARF, including novel antioxidants and antioxidant enzyme mimetics, nitric oxide and nitric oxide synthase inhibitors, erythropoietin, peroxisome-proliferator-activated receptor agonists, inhibitors of poly(ADP-ribose) polymerase, carbon monoxide-releasing molecules, statins, and adenosine. Novel approaches such as recent research involving combination therapies and the potential of non-pharmacological strategies are also considered.