Exenatide Reduces Graft Injury in a Rat Transplantation Model Using Kidneys Donated after Cardiac Death

Besides being used in the therapy of type 2 diabetes, exenatide reduces cerebral ischemia-reperfusion (I/R) injury. We evaluated the potential effects of exenatide on inhibition of apoptosis in kidney grafts donated after cardiac death and on reduction of I/R injury after kidney transplantation (KTx) in a rat model. We used a rat syngeneic KTx model with kidney grafts obtained after cardiac death, and apoptosis was detected in the graft before KTx. Graft function, rat survival, morphologic examination, and activation of inflammatory molecules were analyzed after KTx. By the end of the cold storage, exenatide pretreatment donors had significantly reduced caspase pathway activation, terminal deoxynucleotidyl transferase dUTP nick-end labeling--positive cells, release of mitochondrial porin proteins into the cytosol, and expression of cleaved caspase-3 and poly (ADP-ribose) polymerase in kidney grafts. Exenatide pretreatment improved renal function survival rate with lower scores of acute tubular necrosis, infiltrating macrophages, and interstitial fibrosis as well as reduced messenger RNA expression of inflammatory mediators (tumor necrosis factor α, interleukin-6, interleukin-1β, and intercellular adhesion molecule-1) after KTx. Our study showed that exenatide reduced I/R injury in kidneys donated after cardiac death in a rat transplantation model and improved recipient survival and graft function.     

Comparison of pulsatile perfusion and cold storage for paired kidney allografts

Use of pulsatile perfusion to optimize outcomes in deceased donor kidney transplantation remains controversial. This study is a retrospective analysis of all cadaveric renal allografts procured locally by our center over a 3-year period. Kidney pairs were identified in which one kidney underwent pulsatile perfusion and transplantation at our center, whereas the contra-lateral kidney underwent cold storage and transplantation at another center. Eighty-eight percent of the exported kidneys were six-antigen matches. Study outcomes included 1-year graft and patient survival, delayed graft function, and need for posttransplant dialysis. Recipients had similar demographic and disease characteristics. Survival for pulsatile perfusion and cold storage were 95% and 88% (graft, P=0.43) and 98% and 90% (patient, P=0.36), respectively. The incidence of delayed graft function was 5% and 35% (P<0.01), whereas posttransplant dialysis was 5% and 30% (P<0.01), for pulsatile perfusion and cold storage, respectively. These data support routine use of pulsatile perfusion.     

Hydrogen Sulfide Protects Renal Grafts Against Prolonged Cold Ischemia–Reperfusion Injury via Specific Mitochondrial Actions

Ischemia–reperfusion injury is unavoidably caused by loss and subsequent restoration of blood flow during organ procurement, and prolonged ischemia–reperfusion injury IRI results in increased rates of delayed graft function and early graft loss. The endogenously produced gasotransmitter, hydrogen sulfide (H₂S), is a novel molecule that mitigates hypoxic tissue injury. The current study investigates the protective mitochondrial effects of H₂S during in vivo cold storage and subsequent renal transplantation (RTx) and in vitro cold hypoxic renal injury. Donor allografts from Brown Norway rats treated with University of Wisconsin (UW) solution + H₂S (150 μM NaSH) during prolonged (24‐h) cold (4°C) storage exhibited significantly (p < 0.05) decreased acute necrotic/apoptotic injury and significantly (p < 0.05) improved function and recipient Lewis rat survival compared to UW solution alone. Treatment of rat kidney epithelial cells (NRK‐52E) with the mitochondrial‐targeted H₂S donor, AP39, during in vitro cold hypoxic injury improved the protective capacity of H₂S >1000‐fold compared to similar levels of the nonspecific H₂S donor, GYY4137 and also improved syngraft function and survival following prolonged cold storage compared to UW solution. H₂S treatment mitigates cold IRI–associated renal injury via mitochondrial actions and could represent a novel therapeutic strategy to minimize the detrimental clinical outcomes of prolonged cold IRI during RTx.     

Cold preservation mediated renal injury: involvement of mitochondrial oxidative stress

Cold preservation has greatly facilitated the use of cadaveric kidneys for renal transplantation, but, clearly, damage occurs during both the preservation episode and the reperfusion phase (following transplantation). The aims of this study were twofold: to develop an in vivo model that was capable of evaluating renal function at early time points following cold preservation, and to evaluate the extent of renal mitochondrial damage that occurs following short periods of cold preservation in vivo. To accomplish these goals, we developed a novel rat model of in vivo renal cold ischemia followed by warm reperfusion (cold I/R) which avoided the complexity involved with transplantation. Briefly, after a right nephrectomy, cold I/R was initiated via pulsatile perfusion (40 minutes) of the left kidney with a cold University of Wisconsin solution followed by 18 hours of warm reperfusion. Cold I/R resulted in significant renal injury, nitrotyrosine production, and inactivation of the key mitochondrial antioxidant enzyme, manganese superoxide dismutase. Furthermore, the activities of the mitochondrial respiratory complexes were significantly reduced following cold I/R. In conclusion, short-term cold I/R results in inactivation of MnSOD, which may lead to the inhibition of mitochondrial complexes and subsequent renal injury. These data suggest that compounds designed to prevent early mitochondrial injury in kidneys that undergo cold preservation would significantly improve renal function and graft survival following transplantation.     

Atorvastatin donor pretreatment prevents ischemia/reperfusion injury in renal transplantation in rats: possible role for aldose-reductase inhibition

BACKGROUND: The aim of the present study was to evaluate the effect of donor pretreatment with atorvastatin on ischemia/reperfusion (I/R) injury in renal transplantation in rats. METHODS: Donor rats were pretreated orally with atorvastatin or vehicle 2 days prior to explantation. Kidneys were stored for 24 hr at 4 degrees C in University of Wisconsin solution and transplanted into isogeneic or allogeneic recipients. RESULTS: Donor treatment with atorvastatin improved initial graft function, reduced renal inflammation, and the number of TUNEL-positive cells in renal tissue after prolonged cold storage and isogeneic transplantation. In the allogeneic transplantation model, donor treatment with atorvastatin reduced renal inflammation in grafts harvested after 5 days, but no improvement of long-term graft survival (24 weeks) could be observed. A genome wide gene expression profile of donor kidneys from atorvastatin treated or vehicle treated rats revealed a fivefold downregulation of aldose reductase in all atorvastatin treated animals (P<0.01). Donor treatment with an aldose-reductase inhibitor improved kidney function and reduced renal inflammation after prolonged cold storage and isogeneic transplantation. CONCLUSION: Our data suggest that downregulation of aldose reductase in renal tissue might underlie the protective effect of donor atorvastatin treatment. Donor pretreatment with a statin or an aldose reductase inhibitor could offer a new treatment strategy to prevent transplantation associated tissue injury.     

Ischemic preconditioning improves rat kidney graft function after severe ischemia/reperfusion injury

Ischemic preconditioning (IP) has been shown to ameliorate renal ischemia reperfusion injury. Using a rat kidney transplantation model we determined if IP improves graft function after prolonged cold storage. MATERIALS AND METHODS: Syngeneic rat kidneys were divided into two groups. Prior to 42 hours of cold storage in UW and transplantation, one group (n = 10) received IP (15 minutes of warm ischemia/10 minutes of reperfusion), whereas another group (n = 10) received no treatment. Early graft function and 1-week recipient survival were assessed. RESULTS: Recipient survival was not significantly different between groups [70% (IP) vs 40% (non-IP); P = .28]. IP treatment led to a quicker recovery of renal function. On PODs 3 and 6, serum creatinine levels in the IP group were significantly lower compared with the untreated group. In conclusion, one cycle of IP (15/10) accelerates recovery of renal graft function after severe ischemia reperfusion injury. This simple treatment modality may improve outcomes of renal transplants with prolonged cold storage.     

Carbon monoxide inhibits apoptosis during cold storage and protects kidney grafts donated after cardiac death

Ischemia/reperfusion (I/R) injury remains as a serious deleterious factor in kidney transplantation (KTx). We hypothesized that carbon monoxide (CO), an endogenous potent cytoprotective molecule, inhibits hypothermia-induced apoptosis of kidney grafts. Using the rat KTx model mimicking the conditions of donation after cardiac death (DCD) as well as nontransplantable human kidney grafts, this study examined effects of CO in preservation solution in improving the quality of marginal kidney grafts. After cardiac cessation, rat kidneys underwent 40 min warm ischemia (WI) and 24 h cold storage (CS) in control UW or UW containing CO (CO-UW). At the end of CS, kidney grafts in control UW markedly increased mitochondrial porin release into the cytosol and resulted in increased cleaved caspase-3 and PARP expression. In contrast, grafts in CO-UW had significantly reduced mitochondrial breakdown and caspase pathway activation. After KTx, recipient survival significantly improved with CO-UW with less TUNEL(+) cells and reduced mRNA upregulation for proinflammatory mediators (IL-6, TNF-α, iNOS). Furthermore, when nontransplantable human kidney grafts were stored in CO-UW for 24 h, graft PARP expression, TUNEL(+) cells, and proinflammatory mediators were less than those in control UW. CO in UW inhibited hypothermia-induced apoptosis and significantly improved kidney graft function and outcomes of KTx.     

Effect of Cold Ischemia Time on Kidney Graft Function and Survival: Differences Between Paired Kidney Transplants From the Same Donor

Introduction

Kidney transplantation procedures commonly result in a cold ischemia time (CIT) gap when both kidney grafts are implanted in the same center. Owing to logistics, the procedure is usually consecutive, first accomplishing one surgery and then the other. CIT constitutes an independent risk factor for the development of delayed graft function (DGF) in kidney transplants. The effect that CIT exerts on graft and patient survival is still unclear. This study evaluates the relation of CIT and transplant outcomes by comparing paired kidney transplants in terms of survival and graft function.

Rabbit anti‐rat thymocyte immunoglobulin preserves renal function during ischemia/reperfusion injury in rat kidney transplantation

Ischemia/reperfusion (I/R) injury is an important cause of renal graft dysfunction in humans. Increases in cold and warm ischemia times lead to a higher risk of early post‐transplant complications including delayed graft function and acute rejection. Moreover, prolonged cold ischemia is a predictor of long‐term kidney graft loss. The protective effect of rabbit anti‐rat thymocyte immunoglobulin (rATG) was evaluated in a rat model of I/R injury following syngeneic kidney transplantation. Serum creatinine concentration was evaluated at 16 h and 24 h post‐transplant. Animals were sacrificed 24 h post‐transplant for evaluation of histology, infiltrating leukocytes, nitrotyrosine staining, and apoptosis. rATG was effective in preventing renal function impairment, tissue damage and tubular apoptosis associated with I/R only when was given 2 h before transplantation but not at the time of reperfusion. Pretransplant rATG treatment of recipient animals effectively reduced the amount of macrophages, CD4⁺, CD8⁺ T cells and LFA‐1⁺ cells infiltrating renal graft subjected to cold ischemia as well as granzyme‐B expression within ischemic kidney. On the other hand, granulocyte infiltration and oxidative stress were not modified by rATG. If these results will be translated into the clinical setting, pretransplant administration of Thymoglobuline^® could offer the additional advantage over peri‐transplant administration of limiting I/R‐mediated kidney graft damage.     

Kidney Transplantation in Old Recipients From Old Donors: A Single-Center Experience

Purpose

The program Old for Old or European Senior Program (ESP), allocates donors aged ≥65 years to recipients of ≥65, within a narrow geographic area in order to minimize cold ischemia time, decrease the waiting time for elderly patients listed for kidney transplantation and expand the transplant resource in this group. The ESP is not officially applied in Greece. In our center, the Old for Old criteria have been used since 2003 for elderly patients who are candidates for kidney transplantation.

Surgical complications and cardiovascular comorbidity – Substantial non-immunological confounders of survival after living donor kidney transplantation

Background

Surgical complications following kidney transplantation compromise immediate graft survival. However, the role of early surgical complications in the impairment of long-term survival is not completely established due to various other influences, such as patient comorbidities. The purpose of this study was to characterize the impact of surgical complications and overlapping patient comorbidities on graft function and survival after living donor kidney transplantation (LDKT).

Protection Against Ischemia/Reperfusion Injury in Cardiac and Renal Transplantation with Carbon Monoxide, Biliverdin and Both

Both carbon monoxide (CO) and biliverdin, products of heme degradation by heme oxygenase, have been shown to attenuate ischemia/reperfusion (I/R) injury. We hypothesized in this study that dual-treatment with CO and biliverdin would induce enhanced protective effects against cold I/R injury. Heterotopic heart and orthotopic kidney transplantation were performed in syngeneic Lewis rats after 24-h cold preservation in UW solution. While monotherapy with CO (20 ppm) or biliverdin (50 mg/kg, ip) did not alter the survival of heart grafts, dual-treatment increased survival to 80% from 0% in untreated recipients, with a significant decrease of myocardial injury and improved cardiac function. Similarly, dual-treatment significantly improved glomerular filtration rates of renal grafts and prolonged recipient survival compared to untreated controls. I/R injury-induced up-regulation of pro-inflammatory mediators (e.g. TNF-alpha, iNOS) and extravasation of inflammatory infiltrates were significantly less with dual-treatment than untreated controls. In addition, dual-treatment was effective in decreasing lipid peroxidation and improving graft blood flow through the distinctive action of biliverdin and CO, respectively. The study shows that the addition of byproducts of heme degradation with different mechanisms of action provides enhanced protection against transplant-associated cold I/R injury of heart and kidney grafts.     

Effect of pre-treatment with catecholamines on cold preservation and ischemia/reperfusion-injury in rats

Treatment of organ donors with catecholamines reduces acute rejection episodes and improves long-term graft survival after renal transplantation. The aim of this study was to investigate the effect of catecholamine pre-treatment on ischemia/reperfusion (I/R)- and cold preservation injury in rat kidneys. I/R-injury was induced by clamping the left kidney vessels for 60 min along with a contralateral nephrectomy. Cold preservation injury was induced by storage of the kidneys for 24 h at +4 degrees Celsius in University of Wisconsin solution, followed by syngeneic transplantation. Rats were pre-treated with either dopamine (DA), dobutamine (DB), or norepinephrine (2, 5, and 10 microg/kg/min, each group) intravenously via an osmotic minipump for 24 h before I/R- and cold preservation injury. Pre-treatment with DA (2 or 5 microg/kg/min) and DB (5 microg/kg/min) improved recovery of renal function after I/R-injury and dose dependently reduced mononuclear and major histocompatibility complex class II-positive cells infiltrating the kidney after I/R-injury. One day after I/R-injury, upregulation of transforming growth factor (TGF)-beta 1 and 2 and phosphorylation of p42/p44 mitogen-activated protein kinases was observed in kidneys of animals treated with DA or DB. DA (5 microg/kg/min) and DB (5 microg/kg/min) pre-treatment reduced endothelial cell damage after 24 h of cold preservation. Only DA pre-treatment improved renal function and reduced renal inflammation after 24 h of cold preservation and syngeneic transplantation. Our results demonstrate a protective effect of pre-treatment with catecholamines on renal inflammation and function after I/R- or cold preservation injury. This could help to explain the potent organoprotective effects of catecholamine pre-treatment observed in human kidney transplantation.     

Influence of donor pretreatment with dopamine on allogeneic kidney transplantation after prolonged cold storage in rats

BACKGROUND: Retrospective transplant database analysis revealed that administration of catecholamines to organ donors reduces acute rejection episodes and improves graft survival after renal transplantation. In the present study, the authors investigated the influence of dopamine donor pretreatment before prolonged cold storage on short- and long-term graft outcome after allogeneic kidney transplantation. METHODS: Fisher donor rats were treated intravenously for 24 hr with dopamine or isotonic saline, Lewis rats treated with saline served as controls. Explanted kidneys were stored for 24 hr at 4 degrees C in University of Wisconsin solution and transplanted into Lewis rats. RESULTS: Dopamine pretreatment markedly reduced the infiltration of monocytes down to the level of isogeneic controls 5 days after allogeneic transplantation and hastened recovery of renal function in the first days after transplantation. After 24 weeks, serum creatinine and proteinuria were significantly lower in recipients of dopamine-treated grafts. Histologically, dopamine donor pretreatment significantly reduced the severity of chronic allograft nephropathy. Survival of animals that underwent transplantation was improved by dopamine pretreatment of donors (P=0.04). CONCLUSIONS: Pretreatment of organ donors with dopamine improves short- and long-term outcome after prolonged cold storage and subsequent allogeneic kidney transplantation in rats. The authors' experimental data demonstrate that donor treatment is a simple and effective approach for preventing long-term graft loss after kidney transplantation.     

Protection against ischemia/reperfusion injury by the cavitary two-layer method in canine small intestinal transplantation with reduction of reactive oxygen species

BACKGROUND: Ischemia and reperfusion (I/R) injury is a major determinant of early graft dysfunction and long-term graft survival in small intestinal transplantation. The cavitary two-layer method (TLM) has been reported to be superior to the University of Wisconsin cold storage method (UWM) in long-term preservation of canine small intestine. This study was designed to evaluate the protective effect of the cavitary TLM against I/R injury in canine small intestinal transplantation. METHODS: Intestinal grafts harvested from beagles were allotransplanted after 24-hour preservation by UWM (group 1) or the cavitary TLM (group 2). The graft in the controls (group 3) was immediately allotransplanted without preservation. I/R injury was assessed by functional success rates, biochemical assay, graft adenosine triphosphate (ATP) and lipid peroxidation (LPO) concentrations, and histopathologic examination including TUNEL staining for apoptosis. RESULTS: In group 1, ATP recovery was delayed after reperfusion, and most recipients died with hemorrhage of the grafts and lungs. In group 2, graft ATP concentrations recovered rapidly, and I/R injury was prevented with reduced LPO production, resulting in good outcome. CONCLUSIONS: The cavitary TLM protected intestinal grafts against I/R injury evidenced by maintenance of graft ATP levels and reduction of LPO production compared with UWM in canine small intestinal transplantation.     

Transplantation of Cold Stored Porcine Kidneys After Controlled Oxygenated Rewarming

The concept of “controlled oxygenated rewarming” (COR) using ex vivo machine perfusion after cold storage was evaluated as tool to improve renal graft function after transplantation. Renal function after 20 min warm ischemia and 21 h cold storage was studied in an auto‐transplant model in pigs (25–30 kg, n = 6 per group). In the study group, preimplant ex vivo machine perfusion for 90 min was added after cold storage, including gentle warming up of the graft to 20°C (COR). Kidneys that were only cold stored for 21 h served as controls. In vivo follow up was one week; the remaining native kidney was removed during transplantation. COR significantly improved cortical microcirculation upon early reperfusion and reduced free radical mediated injury and cellular apoptosis. Post‐transplant kidney function (peak levels in serum) was also largely and significantly improved in comparison to the control group. A weak inverse correlation was found between renal flow during COR and later peak creatinine after transplantation (r² = 0.5), better values were seen for oxygen consumption, measured during machine perfusion at 20°C (r² = 0.81). Gentle graft rewarming prior to transplantation by COR improves post‐transplant graft outcome and may also be a valuable adjunct in pretransplant graft assessment.     

Comparison of histidine-tryptophan ketoglutarate and University of Wisconsin solutions as primary preservation in renal allografts undergoing pulsatile perfusion

INTRODUCTION: University of Wisconsin (UW) solution is the standard preservation solution for organ transplantation. Histidine-tryptophan ketogluatarate (HTK) solution has been used increasingly for kidney, pancreas, and liver transplantation. This study compared HTK and UW used during kidney procurement with subsequent pulsatile perfusion. METHODS: Between January and October 2003, 91 deceased renal and simultaneous kidney pancreas transplants were performed (UW, n = 41, and HTK, n = 50). There were no differences with regard to donor and recipient demographics or cold ischemia. RESULTS: Delayed graft function occurred in 3 (7%) of UW and 4 (8%) of HTK-preserved kidneys (P = NS). There were no significant differences between patient or graft survival. There was an anticipated difference between total preservative volumes used (HTK: 4.1 +/- 1.0 vs UW: 3.0 +/- 0.5; P < .005). CONCLUSION: UW and HTK appear to have similar efficacy in kidney preservation with pulsatile perfusion. HTK preservation solution can be used safely in conjunction with pulsatile preservation for cold storage of renal allografts.     

Machine Perfusion Preservation Improves Renal Allograft Survival

Machine perfusion (MP) has been used as the kidney preservation method in our center for over 10 years. The first, small (n = 74) prospective, single-blinded randomized study comparing MP and Cold Storage (CS) showed that the incidence of delayed graft function was higher after CS. There have been no reports in the literature on the effect of storage modality on long-term function of renal allografts. This paper presents an analysis of long-term results of renal transplantation in 415 patients operated on between 1994 and 1999. Of those, 227 kidneys were MP-stored prior to KTx. The control group consisted of 188 CS kidney transplants. Kidneys were not randomized to MP or to CS. Donor demographics, medical and biochemical data, cold ischemia time, HLA match and recipient data were collected. Standard triple-drug immunosuppression was administered to both groups. Mortality, graft survival and incidence of return to hemodialysis treatment were analyzed. Despite longer cold ischemia time and poorer donor hemodynamics in MP group, 5-year Kaplan-Meier graft survival was better in MP-stored than in CS-stored kidneys (68.2% vs. 54.2%, p = 0.02). CONCLUSION: In this nonrandomized analysis, kidney storage by MP improved graft survival and reduced the number of patients who returned to dialysis.     

Dual-kidney transplants: long-term results

BACKGROUND: Dual-kidney transplantation, where two usually aged adult kidneys are placed into an adult recipient, is one way to help alleviate the continuing disparity between the number of patients on the kidney transplant waiting list and those who receive kidney transplants each year. The Dual Kidney Registry was developed to analyze donor and recipient data and outcomes at several centers. METHODS: Two hundred eighty-seven patients who have undergone transplantation since 1994 have been entered into the relational database. The patients were followed yearly after initial entry into the database. RESULTS: The mean donor age was 58+/-13 years and the mean terminal creatinine clearance was 77+/-40 mL/min. The mean glomerular sclerosis on procurement biopsy was 16+/-13%. Delayed graft function (DGF), defined as dialysis in the first 7 days after transplantation, was a predictor of poor outcome, and increased cold storage time was a predictor of DGF. The overall incidence of DGF was 27%. In recipients with prompt graft function (PGF), the mean cold storage time was 22+/-9 hr versus 29+/-10 hr in recipients with DGF (P<0.001). The overall 1- and 5-year graft survival was 86% and 69%, respectively. The 1- and 5-year graft survival rates were significantly better in recipients with PGF (90% and 74%) versus DGF (79% and 54%) (P<0.002). CONCLUSIONS: Cold storage time and DGF have a significant impact on the 1- and 5-year graft survival in recipients of dual-kidney transplants. The 5-year graft survival in recipients of dual-kidney transplants is excellent.