A modified University of Wisconsin preservation solution with high-NA+ low-K+ content reduces reperfusion injury of the pig kidney graft

Abdominal Organ Preservation Solutions in the Age of Machine Perfusion

The past decade has been the foreground for a radical revolution in the field of preservation in abdominal organ transplantation. Perfusion has increasingly replaced static cold storage as the preferred and even gold standard preservation method for marginal-quality organs. Perfusion is dynamic and offers several advantages in comparison with static cold storage. These include the ability to provide a continuous supply of new metabolic substrates, clear metabolic waste products, and perform some degree of organ viability assessment before actual transplantation in the recipient. At the same time, the ongoing importance of static cold storage cannot be overlooked, in particular when it comes to logistical and technical convenience and cost, not to mention the fact that it continues to work well for the majority of transplant allografts. The present review article provides an overview of the fundamental concepts of organ preservation, providing a brief history of static cold preservation and description of the principles behind and basic components of cold preservation solutions. An evaluation of current evidence supporting the use of different preservation solutions in abdominal organ transplantation is provided. As well, the range of solutions used for machine perfusion of abdominal organs is described, as are variations in their compositions related to changing metabolic needs paralleling the raising of the temperature of the perfusate from hypothermic to normothermic range. Finally, appraisal of new preservation solutions that are on the horizon is provided.

Improving the viability of tissue-resident stem cells using an organ-preservation solution

Human clinical specimens are a valuable source of tissue‐resident stem cells, but such cells need to be collected immediately after tissue collection. To extend the timescale for collection from fresh human samples, we developed a new extracellular fluid (ECF)‐type preservation solution based on a high‐sodium and low‐potassium solution containing low‐molecular‐weight dextran and glucose, which is used for preservation of organs for transplantation. In this study, we compared the preservation of tissue‐resident stem cells using our ECF solution with that using three other solutions: PBS, Dulbecco’s modified Eagle’s medium and Euro‐Collins solution. These solutions represent a common buffer, a common culture medium and a benchmark organ‐preservation solution, respectively. Lung tissues were removed from mice and preserved for 72 h under low‐temperature conditions. Of the solutions tested, only preservation in the ECF‐type solution could maintain the proliferation and differentiation capacity of mouse lung tissue‐resident stem cells. In addition, the ECF solution could preserve the viability and proliferation of human alveolar epithelial progenitor cells when stored for more than 7 days at 4 °C. The mean viability of human alveolar type II cells at 2, 5, 8 and 14 days of low‐temperature preservation was 90.9%, 84.8%, 85.7% and 66.3%, respectively, with no significant differences up to 8 days. Overall, our findings show that use of our ECF‐type preservation solution may maintain the viability and function of tissue‐resident stem cells. Use of this preservation solution may facilitate the investigation of currently unobtainable human tissue specimens for human stem cell biology.

Here, we describe a newly developed extracellular fluid‐type organ preservation solution that maintained the viability of human lung stem/progenitor cells, such as alveolar type II cells, during 7‐day refrigerated preservation after the collection of lung specimens in local hospitals. This ready‐to‐use solution may be suitable for the transport of human clinical specimens from hospitals to scientific and bioengineering laboratories.

Barriers and Advances in Kidney Preservation

Despite the fact that a significant fraction of kidney graft dysfunctions observed after transplantation is due to ischemia-reperfusion injuries, there is still no clear consensus regarding optimal kidney preservation strategy. This stems directly from the fact that as of yet, the mechanisms underlying ischemia-reperfusion injury are poorly defined, and the role of each preservation parameter is not clearly outlined. In the meantime, as donor demography changes, organ quality is decreasing which directly increases the rate of poor outcome. This situation has an impact on clinical guidelines and impedes their possible harmonization in the transplant community, which has to move towards changing organ preservation paradigms: new concepts must emerge and the definition of a new range of adapted preservation method is of paramount importance. This review presents existing barriers in transplantation (e.g., temperature adjustment and adequate protocol, interest for oxygen addition during preservation, and clear procedure for organ perfusion during machine preservation), discusses the development of novel strategies to overcome them, and exposes the importance of identifying reliable biomarkers to monitor graft quality and predict short and long-term outcomes. Finally, perspectives in therapeutic strategies will also be presented, such as those based on stem cells and their derivatives and innovative models on which they would need to be properly tested.

A basic consideration for porcine liver preservation using a novel continuous machine perfusion device

INTRODUCTION

The aims of this study were to compare extracellular and intracellular-type University of Wisconsin (UW) solutions for liver grafts and to assess oxygenation in this perfusion system.

MATERIALS AND METHODS

The organ preservation system consisted of 3 circulating systems for the portal vein, hepatic artery, and maintenance of the perfusion solution. The portal vein or hepatic artery system had a roller pump, a flow meter, and a pressure sensor. In this study, we perfused livers with UW or extracellular type UW-gluconate at 4°C-6°C for 4 hours. The flow rates at the entrance were 0.5 mL/min/g liver in the portal vein and 0.2 mL/min/liver in the hepatic artery. Orthotopic liver transplantation was performed in pigs: group 1-a, grafts procured after acute hemorrhagic shock were preserved by a solution without O(2); group 1-b, grafts were preserved with O(2); group 2-a, grafts were perfused using intracellular type solution (UW); and group 2-b, grafts were perfused using extracellular-type solution (UW-gluconate).

RESULTS

Effluent aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) levels in group 1-b were lower than those in group 1-a. Survival rates in group 2-a and group 2-b were 1/4 and 3/3, respectively. Effluent AST and LDH levels in the perfusate of group 2-b were lower than group 2-a. Histological study revealed necrosis of hepatocytes and sinusoidal congestion in group 2-a.

CONCLUSION

A beneficial effect of extracellular-type solution with oxygenation in a novel continuous machine preservation system yielded well-preserved liver graft function.

Effect of polyethylene glycol in pig intestinal allotransplantation without immunosuppression

OBJECTIVES

We evaluated whether IGL-1, a graft preservation solution containing polyethylene glycol, improves the outcome of small bowel grafts in comparison to the University of Wisconsin (UW) solution in a pig allotransplantation model.

MATERIALS AND METHODS

Seventeen pigs were randomly allocated to group 1 (n = 10; intestinal allotransplantation with IGL-1) and group 2 (n = 7; allotransplantation with UW). Pigs received no immunosuppression and were sacrificed on postoperative d (POD) 8. Intestinal specimens were obtained from the animal immediately before cold flushing (T0), 2 h after graft reperfusion (T1), and at sacrifice (T2).

RESULTS

Survival rate to POD 8 was 50% in group 1 compared with 16% in group 2 (P < 0.05); 62% of pigs in group 1 did not present any acute cellular rejection (ACR) compared to 16% in group 2 (P < 0.05). Severe ACR rate was 25% in group 1 and 66% in group 2 (P < 0.05). iNOS activity and intestinal caspase 3 levels increased significantly between T0 and T1 in group 1 compared to group 2 (P < 0.05). Cell necrosis increased significantly between TO and T1 in group 2 compared with group 1 (P < 0.05) whereas cell apoptosis was significantly higher at T1 compared with T0 in group 1 in comparison to group 2.

CONCLUSIONS

Our results show that IGL-1 improves intestinal graft viability as compared to UW solution, possibly by reducing graft immunogenicity and by favoring intestinal epithelial repair.

Small bowel preservation for intestinal transplantation: a review

Intestinal transplantation has become the therapy of choice for patients with intestinal failure and life-threatening complications from total parenteral nutrition. Results, however, remain inferior as compared with other transplant types with the quality of the organ graft as the most important factor of outcome after transplantation. The intestine is extremely sensitive to ischemia. Unfortunately, a relatively long ischemic preservation period is inevitable. The current standard in organ preservation [cold storage (CS) with University of Wisconsin solution] was developed for kidney/liver preservation and is suboptimal for the intestinal graft despite good results for other organs. This review aimed at appraising the results from the use of previously applied and recently developed preservation solutions and techniques to identify key areas for improvement. As the studies available do not reveal the most effective method for intestinal preservation, an optimal strategy will result from a synergistic effect of different vital elements identified from a review of published material from the literature. A key factor is the composition of the solution using a low-viscosity solution to facilitate washout of blood, including amino acids to improve viability, impermeants and colloids to prevent edema, and buffer for pH-homeostasis. Optimizing conditions include a vascular flush before CS and luminal preservation. The most effective composition of the luminal solution and a practical, clinically applicable optimal technique are yet to reach finality. Short-duration oxygenated arterial and/or luminal perfusion have to be considered. Thus, a tailor-made approach to luminal preservation solution and technique need further investigation in transplant models and the human setting to develop the ultimate technique meeting the physiologic demands of the intestinal graft during preservation.

Ex vivo application of carbon monoxide in UW solution prevents transplant-induced renal ischemia/reperfusion injury in pigs

I/R injury is a major deleterious factor of successful kidney transplantation (KTx). Carbon monoxide (CO) is an endogenous gaseous regulatory molecule, and exogenously delivered CO in low concentrations provides potent cytoprotection. This study evaluated efficacies of CO exposure to excised kidney grafts to inhibit I/R injury in the pig KTx model. Porcine kidneys were stored for 48 h in control UW or UW supplemented with CO (CO-UW) and autotransplanted in a 14-day follow-up study. In the control UW group, animal survival was 80% (4/5) with peak serum creatinine levels of 12.0 +/- 5.1 mg/dL. CO-UW showed potent protection, and peak creatinine levels were reduced to 6.9 +/- 1.4 mg/dL with 100% (5/5) survival without any noticeable adverse event or abnormal COHb value. Control grafts at 14 days showed significant tubular damages, focal fibrotic changes and numerous infiltrates. The CO-UW group showed significantly less severe histopathological changes with less TGF-beta and p-Smad3 expression. Grafts in CO-UW also showed significantly lower early mRNA levels for proinflammatory cytokines and less lipid peroxidation. CO in UW provides significant protection against renal I/R injury in the porcine KTx model. Ex vivo exposure of kidney grafts to CO during cold storage may therefore be a safe strategy to reduce I/R injury.

Donor treatment with a PHD-inhibitor activating HIFs prevents graft injury and prolongs survival in an allogenic kidney transplant model

Long-term survival of renal allografts depends on the chronic immune response and is probably influenced by the initial injury caused by ischemia and reperfusion. Hypoxia-inducible transcription factors (HIFs) are essential for adaptation to low oxygen. Normoxic inactivation of HIFs is regulated by oxygen-dependent hydroxylation of specific prolyl-residues by prolyl-hydroxylases (PHDs). Pharmacological inhibition of PHDs results in HIF accumulation with subsequent activation of tissue-protective genes. We examined the effect of donor treatment with a specific PHD inhibitor (FG-4497) on graft function in the Fisher-Lewis rat model of allogenic kidney transplantation (KTx). Orthotopic transplantation of the left donor kidney was performed after 24 h of cold storage. The right kidney was removed at the time of KTx (acute model) or at day 10 (chronic model). Donor animals received a single dose of FG-4497 (40 mg/kg i.v.) or vehicle 6 h before donor nephrectomy. Recipients were followed up for 10 days (acute model) or 24 weeks (chronic model). Donor preconditioning with FG-4497 resulted in HIF accumulation and induction of HIF target genes, which persisted beyond cold storage. It reduced acute renal injury (serum creatinine at day 10: 0.66 +/- 0.20 vs. 1.49 +/- 1.36 mg/dL; P < 0.05) and early mortality in the acute model and improved long-term survival of recipient animals in the chronic model (mortality at 24 weeks: 3 of 16 vs. 7 of 13 vehicle-treated animals; P < 0.05). In conclusion, pretreatment of organ donors with FG-4497 improves short- and long-term outcomes after allogenic KTx. Inhibition of PHDs appears to be an attractive strategy for organ preservation that deserves clinical evaluation.

[Solutions for organ preservation and other cardioplegic liquid formulations. Role of the hospital pharmacist]

Solid organ transplantation is an increasing need and a well-established activity which requires maintaining the quality of the transplant from procurement through the entire, storage, transport and graft procedure. Solutions for organ preservation play a key role in this procedure, by minimizing the deleterious effects of both ischemia and reperfusion. As such, their qualitative and quantitative compositions have to be optimized and validated. The development strategy and formulations proposed for these solutions are analyzed in this review as well as the results of the clinical studies which have set up the relevant pharmacological and physicochemical criteria. The French regulatory status of these products is also discussed. A clear distinction has to be made between solutions for organ preservation which are classified as produits thérapeutiques annexes (therapeutic ancillary products) and cardioplegic liquid formulations which are considered as medicinal products and are subject to marketing approval. Finally, the roles of the hospital pharmacist in the evaluation, selection, purchase and proper use of these products are described.

Static cold storage preservation of ischemically damaged kidneys. a comparison between IGL-1 and UW solution

Especially in damaged organs, adequate organ preservation is critically important to maintain viability. Institut Georges Lopez-1 (IGL-1) is a new preservation solution, with an extracellular sodium/potassium ratio and polyethylene glycol as a colloid. The influence of warm and cold ischemia was evaluated in a rat Lewis-Lewis transplant model with a follow up of 14 days. Eight groups of donation after cardiac death donor kidneys were studied with warm ischemia of 0 and 15 min followed by 0- or 24-h cold storage (CS) preservation in IGL-1 or UW-CSS. Blood was collected daily during the first week and at day 14. Recipients were placed in metabolic cages at day 4 and 14 after transplantation allowing urine collection and adequate measurement of glomerular filtration rate. Focussing on inflammation, reactive oxygen species production, proximal tubule damage, proteinuria, histology, and renal function after transplantation we could not show any relevant difference between IGL-1 and UW-CSS. Furthermore, the combination of 15-min warm ischemia and by 24-h cold ischemia did not result in life sustaining kidney function after transplantation, irrespective of the used solution. In the present experiment, static CS preservation of ischemically damaged rat kidneys in either IGL-1 or UW-CSS rendered equal results after transplantation.

Perspectives in organ preservation

Maintaining organ viability after donation until transplantation is critically important for optimal graft function and survival. To date, static cold storage is the most widely used form of preservation in every day clinical practice. Although simple and effective, it is questionable whether this method is able to prevent deterioration of organ quality in the present era with increasing numbers of organs retrieved from older, more marginal, and even non-heart-beating donors. This review describes principles involved in effective preservation and focuses on some basic components and methods of abdominal organ preservation in clinical and experimental transplantation. Concepts and developments to reduce ischemia related injury are discussed, including hypothermic machine perfusion. Despite the fact that hypothermic machine perfusion might be superior to static cold storage preservation, organs are still exposed to hypothermia induced damage. Therefore, recently some groups have pointed at the beneficial effects of normothermic machine perfusion as a new perspective in organ preservation and transplantation.

Influence of Perioperational Acid-Base Balance Disorders on Early Graft Function in Kidney Transplantation

INTRODUCTION

Reperfusion is a crucial moment in kidney transplantation, connected with many metabolic changes that are the result of preservation and intraoperative course including ion movements, free radical generation, ATP and other adenylate depletion. During reperfusion we observed increased metabolic acidosis, which may be the result of accumulation of lactic acid due to anaerobic metabolism, with a simultaneous expiratory pCO(2) growth as respiratory compensation. The study's purpose was to examine acid-base balance dynamics during 30 minutes of reperfusion of the transplanted kidney and its influence on renal function based on observations of the 1-year creatinine values.

MATERIALS AND METHODS

The examined group consisted of 76 recipients: 44 men, 32 women. Measurements by gasometric analysis and expiratory pCO(2) in each patient were performed nine times during reperfusion. In the postoperative period we analyzed donor-related factors including: gender, age, number of HLA matches weight and height, as well as recipient-related factors including: gender, age, basic immunosuppression, creatinine level at hospital discharge and at 5 to 24 months of follow-up. Statistical significance was analyzed using repeated-measures analysis of variance followed by Tukey post hoc test as well as Mann-Whitney U and Spearman's correlation tests.

RESULTS

The analysis showed correlations between reperfusion, acidosis, respiratory pCO(2) compensation, early graft loss, patient death, donor and recipient gender, renal function, donor age, and histocompatibility.

CONCLUSIONS

At the beginning of reperfusion there is increasing metabolic acidosis with simultaneous expiratory pCO(2) as compensation. A greater relative increase in expiratory air pCO(2) was correlated with a higher incidence of early graft loss. The higher intensity of metabolic acidosis correlated with worse renal function at 6 months after transplantation. Elderly donor age and fewer HLA-matched antigens correlated with greater intensity of metabolic acidosis during 30 minutes of kidney reperfusion.

Evaluation of IGL-1 preservation solution using an orthotopic liver transplantation model

AIM: To compare, in a pig liver transplantation model, the protective effect of UW with that of IGL-1, a high-sodium preservation solution containing polyethylene glycol (PEG) as an oncotic supply.

METHODS: All livers were harvested and grafted orthotopically according to standard techniques. The livers were washed out and preserved for 7 h in IGL-1 (n = 6) or in UW solution (n = 7) at 4°C. In a sham group (n = 4), the livers underwent a 60-min warm ischemia at 37°C. The hepatocellular injury was assessed in organ preservation solution washed out from the graft at the end of ischemic storage (before revascularization), and in serum 2 h after reperfusion and daily for up to 6 d.

RESULTS: Livers preserved in IGL-1 solution released markedly less AST than that preserved in the UW solution before and after revascularization (P < 0.05). Besides, the activity of creatine kinase-BB, a marker of sinusoidal lining cells injury, was higher in the UW group than in the IGL-1 group (P < 0.05). Histological results showed less necrotic regions in livers preserved in IGL-1 solution; however, no difference was observed for inflammation.

CONCLUSION: IGL-1 liquid effectively protects parenchymal and non-parenchymal cells against prese-rvation-reperfusion injuries.

Early Acid–Base Balance Disorders During Kidney Transplantation

INTRODUCTION

Reperfusion is a crucial moment in kidney transplantation. Resumption of blood flow is associated with many metabolic changes, which result from the kidney's initial condition and preservation. These biochemical alterations including the acid-base balance are the part of ischemia-reperfusion injury. The study's purpose was to examine acid-base balance during the first 30 minutes after reperfusion of the transplanted kidney.

MATERIALS AND METHODS

The 30 recipients (13 men, 17 women) averaged ages of 46 +/- 14 years. Measurements performed nine times (at 0, 1, 3, 5, 10, 15, 20, 25, and 30 minutes after unclamping renal vessels) included: gas analysis, expiratory Pco(2), tidal volume, and respiratory rate. The evaluation of the temporary acid-base balance was performed on the basis of common parameters: pH, Pco(2), [HCO(3)(-)], and base excess (BE). The patients were under general anesthesia with stable external conditions of O(2) saturation, heart rate, blood pressure, and temperature. Blood samples were analyzed using Corning 278 and 248 blood gas analyzer; vital parameters were recorded using Ohmeda 5250 RGM and Dräger Sulla 909V/Julian apparatus.

RESULTS

The analysis showed increasing metabolic acidosis with coexisting increase in blood Pco(2), changes that were most intense in the first minute of reperfusion. Decreasing mean pH index did not exceed physiologic limits, but the final mean values of [HCO(3)(-)] and BE were in most of cases below the limit. Increased expiratory air Pco(2) was most intense in the first 3 minutes reaching a maximum at about 15 minutes.

CONCLUSIONS

The beginning of reperfusion was the cause of increasing metabolic acidosis, which was partially compensated by blood buffers. Simultaneous increase in expiratory Pco(2), corresponding to the dynamics of acidosis, indicated the existence of respiratory compensation. Sudden increase in acidosis parameters may be the result of lactate accumulation during kidney ischemia. The decreased [HCO(3)(-)] may indicate postreperfusion kidney injury, which must be the subject of further research.

Kidney preservation with IGL-1 solution: a preliminary report

The University of Wisconsin (UW) solution is the most commonly used preservation solution. However, a new preservation solution-IGL-1-contains an inversion of K and Na concentrations and substitution of polyethylene glycol for hydroxyethyl starch in the UW solution. The present study is the first clinical experience on the outcome of kidneys preserved in IGL-1 solution. From June 2003 to June 2004, 119 cadaveric kidneys were retrieved and stored in IGL-1 solutions; among the 119 organs, this study includes 37 IGL-1-preserved kidneys that were locally transplanted versus 33 kidneys stored in University of Wisconsin (UW) solution that were also locally transplanted. The groups were comparable with regard to donor and recipient characteristics. Renal function outcome was evaluated by comparing delayed graft function (DGF) rates, the evolution of serum creatinine, daily urine output, and creatinine clearance. Biopsies were performed after reperfusion to evaluate apoptosis. The incidence of DGF was 5.71% among IGL-1 kidneys and 13.79% among UW kidneys. Creatinine values were significantly lower among the IGL-1 group from 2 to 14 days postoperative and at 1 month. Daily urinary output did not show any significant differences between the two groups. IGL-1 kidneys had a superior creatinine clearance during the first 15 postoperative days compared to UW kidneys. Kidneys preserved in IGL-1 solution showed fewer apoptotic cells compared to kidneys preserved in UW solution. This preliminary report suggests a superiority of IGL-1 for the immediate outcome of transplanted kidneys.

Delayed graft function in renal transplantation

PURPOSE OF REVIEW

Delayed graft function is an important determinant of patient and graft survival. A complex of pathologic mechanisms intervenes in the pathophysiology of this outcome. This paper reviews the main processes involved in delayed graft function as they relate to five chronologically related stages: donor tissue quality, brain death and related stress, preservation variables, immune factors, and recipient variables.

RECENT FINDINGS

Dialyzed delayed graft function and nondialyzed slow graft function both have a negative impact on graft survival and on the incidence of acute rejection. Expanded-criteria donors, older donors, and non-heart-beating donors are more frequently used. The long-term results of the use of well-selected non-heart-beating donors are surprisingly good. The process of ischemia/reperfusion injury is already initiated in the brain-death donor and continues during preservation of the graft. Graft-infiltrating T cells, heat shock proteins, and heme oxygenase-1 are implicated in the process. Modifications in immunosuppressive therapy and pharmacologic modulations have an effect on delayed graft function. Delayed graft function plays a part in the incidence of acute rejection, impaired graft function, and survival of patients and grafts.

SUMMARY

This review discusses the current literature on several recent findings of pathophysiologic mechanisms of, and possible therapeutic interventions in, delayed graft function.

Evaluation of CMU-1 preservation solutions using an isolated perfused rat liver model

AIM: CMU-1 is a new preservation solution with a low potassium concentration as well as low viscosity that is highly effective in reducing preservation injury. The purpose of this experiment is to compare the protective effect of CMU-1 solution with that of UW during cold preservation and normothermic reperfusion.

METHODS: Wistar rats were divided into two groups according to different preservation solution: CMU-1 group and UW group. After 6, 12 and 24 h cold storage of rat liver in different preservation solutions, the isolated perfused rat liver model was applied to reperfuse the liver for 120 min normothermically (37 °C) with Krebs-Henseleit solution, meanwhile the pH value of the preservation solution was measured. The perfusate was sampled for the evaluation of alanine aminotransferase (ALT) and lactate dehydrogenase (LDH). At the end of the reperfusion, all of the bile product was collected, energy metabolic substrate and histological examination were performed.

RESULTS: After preserving for 6 h, pH value of both groups did not change; after 12 h, both decreased but with no significant difference. After 24 h, pH value in UW solution group significantly decreased. The total adenine nucleotides level and AEC in liver tissue decreased with preservation time, but they were higher in CMU-1 group. And the amount of bile product after perfusion for 120 min in CMU-1 group was much more than that in UW group. However, there were no significant differences in ALT and LDH levels between two groups. Histology showed no difference.

CONCLUSION: The preservation effect of CMU-1 solution is similar with that of UW solution. However, CMU-1 solution shows some advantages over UW solution in energy meta-bolism, preventing intracellular acidosis and bile product.

Effect of IGL-1, a new preservation solution, on kidney grafts (a pre-clinical study)

Ischemia-reperfusion injury conditions short-term and long-term graft function. The effects of the inversion of K+ and Na+ concentrations and substitution with polyethylene glycol for hydroxyethyl starch in University of Wisconsin (K-UW) solution were evaluated in isolated perfused rat kidneys and in autotransplanted pig kidneys. In the rat model kidneys were cold-stored for 24 h in K-UW or Na-UW or Na-PEG UW solutions (IGL-1 solution). Fractional sodium reabsorption and glomerular filtration rate was better in kidneys preserved in Na-UW and IGL-1 solution than those preserved in K-UW solution. In the pig model the left kidney was harvested and preserved in K-UW or IGL-1 solution for 24 h and then transplanted. In the autotransplanted pig model, kidneys preserved in IGL-1 solution showed a better function and a significant reduction of MHC class II expression, cellular apoptosis and interstitial fibrosis. In conclusion, kidneys preserved in IGL-1 solution tolerated ischemia/reperfusion injury better than those preserved in K-UW solution.

Influence of colloid, preservation medium and trimetazidine on renal medulla injury

In organ transplantation, preservation injury is an important factor which could influence short-term and long-term graft outcome. The renal medulla is particularly sensitive to oxidant stress and ischemia-reperfusion injury (IRI). Using an autotransplant pig kidney model, we investigated renal function and medullary damage determined between day 1 and week 2 after 24- or 48-h cold storage in different preservation solutions: University of Wisconsin solution (UW), Hopital Edouard Herriot solution (a high Na+ version of UW), ECPEG (high Na+ preservation solution with PEG) and ICPEG (a high K+ version of ECPEG) with or without trimetazidine (TMZ). TMZ improved renal preservation and increased renal function when added in each preservation solution (particularly HEH and ECPEG). Medullary damage led to the early appearance of trimethylamine-N-oxide (TMAO) followed by 1H-NMR in urine and plasma. TMZ and ECPEG is the most efficient association to reduce medullary damage. This study clarifies the role of colloid and polarity solution and the role of mitochondrial protection by TMZ.

Protective roles of polyethylene glycol and trimetazidine against cold ischemia and reperfusion injuries of pig kidney graft

Ischemia-reperfusion injury (IRI) represents an allo-independent risk factor which favors chronic allograft nephropathy (CAN). Here we analyzed the influence of preservation solutions on the function of autotransplanted pig kidneys over 1-16 weeks after surgery. Kidneys were cold-flushed and cold-stored for 24 or 48 h either in University of Wisconsin (UW), modified-UW Hôpital Edouard Herriot, polyethylene glycol 20 kDa (PEG)-supplemented preservation solutions with low K+ (ECPEG) or high K+ (ICPEG) content. Animals autotransplanted with kidneys cold-stored for 24 h in ECPEG exhibited the greatest levels of creatinine clearance (Ccr: 161 +/- 12 mL/min, n=10) and the lowest levels of proteinuria (0.5 +/- 0.03 mg/mL) 16 weeks after surgery as compared with pigs autotransplanted with kidneys cold-stored in the other solutions tested (Ccr ranging from 80 and 140 mL/min). Similar differences, but with lower Ccr levels, were achieved after a prolonged period of cold-storage(48 h). ECPEG better preserved the kidneys from monocytes/macrophages and CD4+ T cells infiltrations, VCAM-1 and MHC class II overexpressions and occurrence of renal interstitial fibrosis (2%) as compared with the other preservation solutions (5%-20%). Adding the anti-ischemic drug trimetazidine (TMZ) to the preservation solutions, particularly ECPEG, further improved the quality of the week-16 post-transplanted kidneys (Ccr: 182 +/- 12 mL/min, n=10). These findings demonstrated that adding PEG to extracellular-like (with low K+ content) preservation solutions in combination with TMZ significantly improved the long-term outcome of kidney grafts in this model of autotransplanted pig kidney.