Machine Perfusion System Research Articles

A simplified subnormothermic machine perfusion system restores ischemically damaged liver grafts in a rat model of orthotopic liver transplantation

BackgroundLiver donor shortages stimulate the development of strategies that incorporate damaged organs into the donor pool. Herein we present a simplified machine perfusion system without the need for oxygen carriers or temperature control, which we validated in a model of orthotopic liver transplantation.MethodsRat livers were procured and subnormothermically perfused with supplemented Williams E medium for 3 hours, then transplanted into healthy recipients (Fresh-SNMP group). Outcome was compared with static cold stored organs (UW-Control group). In addition, a rat liver model of donation after cardiac death was adapted using a 60-minute warm ischemic period, after which the grafts were either transplanted directly (WI group) or subnormothermically perfused and transplanted (WI-SNMP group).ResultsOne-month survival was 100% in the Fresh-SNMP and UW-Control groups, 83.3% in the WI-SNMP group and 0% in the WI group. Clinical parameters, postoperative blood work and histology did not differ significantly between survivors.ConclusionThis work demonstrates for the first time in an orthotopic transplantation model that ischemically damaged livers can be regenerated effectively using practical subnormothermic machine perfusion without oxygen carriers.

Functional Recovery of Donation After Cardiac Death Liver Graft by Continuous Machine Perfusion Preservation in Pigs

IntroductionGrafts from donation after cardiac death (DCD) will greatly contribute to the expand the donor pool. However, these grafts may require the development of the preservation methods because of primary nonfunction and severe ischemic bile duct injury. MethodsPorcine livers were perfused with a newly developed machine perfusion (MP) system. Each system for the portal vein or the hepatic artery had a roller pump, a flow meter, and a pressure sensor. The livers were perfused with University of Wisconsin (UW)-gluconate at 4°C–6°C for 3 hours after 2 hours simple cold storage (CS). The portal vein flow rate was 0.5 mL/min/g liver (pressure, 10 mm Hg) and the hepatic artery flow rate was 0.2 mL/min/g liver (pressure, 30 mm Hg). Orthotopic liver transplantation was performed in pigs comparing Group 1 (n = 4) procured after acute hemorrhagic shock preserved by MP, Group 2 (n = 3) procured after warm ischemia time (WIT) of 30 minutes with CS preservation, and Group 3 (n = 4) procured with 30 minutes of WIT and MP preservation. ResultsCollected effluent aspartate aminotransferase (AST) and lactate dehydrogenase (LDH) levels in the perfusion solution and serum AST and LDH were significantly lower in Group 1. AST and LDH results were lower in Group 3 than Group 2. Survival rates in Groups 1 and 3 were 3/4, but 0/3 in Group 2. ConclusionMP preservation was a useful promising preservation mode for DCD liver grafts.

An Innovative Hyperbaric Hypothermic Machine Perfusion Protects the Liver from Experimental Preservation Injury

Purpose. Hypothermic machine perfusion systems seem more effective than the current static storage to prevent cold ischemic liver injury. Thus, we test an innovative hyperbaric hypothermic machine perfusion (HHMP), which combines hyperbaric oxygenation of the preservation solution and continuous perfusion of the graft. Methods. Rat livers were preserved with Celsior solution according to 4 different modalities: normobaric static preservation; hyperbaric static preservation at 2 atmosphere absolute (ATA); normobaric dynamic preservation, with continuous perfusion; hyperbaric dynamic preservation, with continuous perfusion at 2 ATA. After 24 h cold preservation, we assessed different parameters. Results. Compared to baseline, livers preserved with the current static storage showed severe ultrastructural damage, glycogen depletion and an increased oxidative stress. Normobaric perfused livers showed improved hepatocyte ultrastructure and ameliorated glycogen stores, but they still suffered a significant oxidative damage. The addition of hyperbaric oxygen produces an extra benefit by improving oxidative injury and by inducing endothelial NO synthase (eNOS) gene expression. Conclusions. Preservation by means of the present innovative HHMP reduced the liver injury occurring after the current static cold storage by lowering glycogen depletion and oxidative damage. Interestingly, only the use of hyperbaric oxygen was associated to a blunted oxidative stress and an increased eNOS gene expression.

Altered alkaline phosphatase activity in obese Zucker rats liver respect to lean Zucker and Wistar rats discussed in terms of all putative roles ascribed to the enzyme

Biliary complications often lead to acute and chronic liver injury after orthotopic liver transplantation (OLT). Bile composition and secretion depend on the integrated action of all the components of the biliary tree, starting from hepatocytes. Fatty livers are often discarded as grafts for OLT, since they are extremely vulnerable to conventional cold storage (CS). However, the insufficiency of donors has stimulated research to improve the usage of such marginal organs as well as grafts. Our group has recently developed a machine perfusion system at subnormothermic temperature (20°C; MP20) that allows a marked improvement in preservation of fatty and even of normal rat livers as compared with CS. We sought to evaluate the response of the biliary tree of fatty liver to MP20, and a suitable marker was essential to this purpose. Alkaline phosphatase (AlkP, EC 3.1.3.1), frequently used as marker of membrane transport in hepatocytes and bile ducts, was our first choice. Since no histochemical data were available on AlkP distribution and activity in fatty liver, we have first settled to investigate AlkP activity in the steatotic liver of fatty Zucker rats (fa/fa), using as controls lean Zucker (fa/+) and normal Wistar rats. The AlkP reaction in Wistar rats was in accordance with the existing data and, in particular, was present in bile canaliculi of hepatocytes in the periportal region and midzone, in the canals of Hering and in small bile ducts but not in large bile ducts. In lean ZR liver the AlkP reaction in Hering canals and small bile ducts was similar to Wistar rat liver but hepatocytes had lower canalicular activity and besides presented moderate basolateral reaction. The difference between lean Zucker and Wistar rats, both phenotypically normal animals, could be related to the fact that lean Zucker rats are genotypically heterozygous for a recessive mutated allele. In fatty liver, the activity in ductules and small bile ducts was unchanged, but most hepatocytes were devoid of AlkP activity with the exception of clusters of macrosteatotic hepatocytes in the mid-zone, where the reaction was intense in basolateral domains and in distorted canaliculi, a typical pattern of cholestasis. The interpretation of these data was hindered by the fact that the physiological role of AlkP is still under debate. In the present study, the various functions proposed for the role of the enzyme in bile canaliculi and in cholangiocytes are reviewed. Independently of the AlkP role, our data suggest that AlkP does not seem to be a reliable marker to study the initial step of bile production during OLT of fatty livers, but may still be used to investigate the behaviour of bile ductules and small bile ducts.

Hypothermic Machine Perfusion of Kidney Grafts: Which Pressure is Preferred?

To assess the effect of the perfusion pressure (PP) during machine perfusion (MP) on the preservation quality of kidney grafts, we compared mean PPs of 25 and 30mmHg using a porcine autotransplantation model. After assessment of the microcirculation, animals underwent left nephrectomy. Thereafter, kidneys were washed out followed by 20h of MP at 25mmHg (MP25, n=7) or 30mmHg (MP30, n=7) using a novel MP system for hypothermic pulsatile perfusion. After MP preservation, the contralateral kidneys were removed and the preserved kidneys heterotopically autotransplanted. Ten minutes after reperfusion, the microcirculation was reassessed. Seven days posttransplant, animals were euthanized and the kidney grafts removed for histological analysis. MP using a mean PP of 25mmHg resulted in higher capillary blood flow after reperfusion. In the MP30 group, 6 out of 7 animals survived, whereas in the MP25 group all animals survived. Overall, improvement in recovery of renal function and a better preservation of structural integrity were seen in the MP25 group compared to the MP30 group. Using a novel system for hypothermic MP, a mean PP of 25mmHg is preferred over a mean PP of 30mmHg.

Diluted Blood Reperfusion as a Model for Transplantation of Ischemic Rat Livers: Alanine Aminotransferase Is a Direct Indicator of Viability

Donors after cardiac death present a significant pool of untapped organs for transplantation, and use of machine perfusion strategies has been an active focus area in experimental transplantation. However, despite 2 decades of research, a gold standard has yet to emerge for machine perfusion systems and protocols. Whole blood reperfusion has been used as a surrogate for organ transplantation, especially as a model for the short-term response posttransplantation, and for optimization of perfusion systems. Although it is known that there is a strong correlation between liver function in whole-blood reperfusion and survival, the exact nature of these correlations, and to what extent they can be considered as an indicator of viability for transplantation/recipient survival, remain unclear. In this work, we demonstrate that diluted whole-blood reperfusion can be used as a direct model for transplantation of ischemic rat liver grafts. Specifically, we show that recipient survival can be predicted based simply on the value of alanine aminotransferase during perfusion, providing quantitative criteria of viability for use in this animal model. These results indicate that in the rat model graft survival is highly correlated with hepatocellular damage.

Continuous Real-time Viability Assessment of Kidneys Based on Oxygen Consumption

Background Current ex vivo quality assessment of donor kidneys is limited to vascular resistance measurements and histological analysis. New techniques for the assessment of organ quality before transplantation may further improve clinical outcomes while expanding the depleted deceased-donor pool. We propose the measurement of whole organ oxygen consumption rate (WOOCR) as a method to assess the quality of kidneys in real time before transplantation. Methods Five porcine kidneys were procured using a donation after cardiac death (DCD) model. The renal artery and renal vein were cannulated and the kidney connected to a custom-made hypothermic machine perfusion (HMP) system equipped with an inline oxygenator and fiber-optic oxygen sensors. Kidneys were perfused at 8°C, and the perfusion parameters and partial oxygen pressures (pO 2) were measured to calculate WOOCR. Results Without an inline oxygenator, the pO 2 of the perfusion solution at the arterial inlet and venous outlet diminished to near 0 within minutes. However, once adequate oxygenation was provided, a significant pO 2 difference was observed and used to calculate the WOOCR. The WOOCR was consistently measured from presumably healthy kidneys, and results suggest that it can be used to differentiate between healthy and purposely damaged organs. Conclusions Custom-made HMP systems equipped with an oxygenator and inline oxygen sensors can be applied for WOOCR measurements. We suggest that WOOCR is a promising approach for the real-time quality assessment of kidneys and other organs during preservation before transplantation.

One Hour Hypothermic Oxygenated Perfusion (HOPE) Protects Nonviable Liver Allografts Donated After Cardiac Death

To test, in a large animal model, the efficacy of machine perfusion to rescue livers after prolonged ischemic injury. Our group previously showed in various rodent models the benefit of endischemic hypothermic oxygenated perfusion (HOPE) in protecting liver injury from donation after cardiac death (DCD). Convincing results are needed in large animal models before application in human. A new model of DCD liver transplantation in large pigs was developed. Pig livers (1300 +/- 210 g each) were harvested 60 minutes after induction of cardiac death (respirator withdrawal). In situ flush and organ procurement were initiated without heparin pretreatment. Then, livers were preserved for 7 hours in cold Celsior (DCD-group) prior to orthotopic transplantation (OLT). Some livers were treated by 1 hour HOPE prior to implantation (HOPE-group). In a first step, animals were kept under anesthesia for 6 hours after orthotopic transplantation. Endpoints included serum (AST) and tissue (ATP, glutathione) markers of injury, bile flow, and histology. In a second step, survival experiments were performed. Livers from the DCD group displayed diffuse necrosis of hepatocytes, increased adhesion of platelets, high AST release, absence of bile flow, depletion of glutathione, and ATP. In contrast, livers treated with HOPE showed dramatic reduction of necrosis, platelet adhesion, while bile flow, ATP recovery and glutathione were improved. Importantly, untreated DCD livers caused graft failure and death of all recipients within 6 hours of reperfusion, whereas HOPE treated DCD livers remained hemodynamically stable. This is the first study in a reliable large animal transplant model demonstrating the efficacy of a simple cold oxygenated machine perfusion system to rescue, otherwise lethal, ischemic injured DCD liver grafts.

Evaluation of a Novel System for Hypothermic Oxygenated Pulsatile Perfusion Preservation

Recently, a novel innovative machine perfusion (MP) system for hypothermic oxygenated pulsatile perfusion called the Airdrive (AD) has been developed. The aim of the study was to evaluate the biological safety of the AD system for perfusion preservation of kidney grafts in a porcine autotransplantation model using the low-viscosity perfusion solution Polysol (PS) in comparison with cold storage (CS) using PS or the University of Wisconsin solution (UW). In addition, we evaluated real-time microcirculation parameters. At sacrifice, grafts were retrieved for histological analysis and immunohistochemistry. After assessment of the microcirculation, left kidneys were retrieved. Following the washout, kidneys were preserved for 20 hr using AD-PS, CS-PS or CS-UW. Thereafter, contralateral kidneys were removed followed by heterotopic autotransplantation of the preserved graft. Seven days after transplantation animals were sacrificed with retrieval of the grafts for histological analysis. Renal function, renal microcirculation and tissue injury including the proliferative response of tubular epithelial cells (TECs) were compared. Preservation using AD-PS or CS-PS resulted in higher microcirculatory flow compared with CS-UW. Improved recovery of renal function was seen in the AD-PS and CS-PS groups compared with CS-UW. Structural integrity was better preserved using AD-PS compared with both CS groups. Proliferative response of TECs was higher in CS-UW preserved grafts compared to grafts preserved using AD-PS. This study demonstrates the biological safety of the AD system in a porcine autotransplantation model. Also, the microcirculation was better preserved and less morphological injury was observed after 20 hr MP compared with CS.

Abdominal Transplant Surgery and Transplant Coordination University Hospitals Leuven 1997–2007: an Overview

The transplant surgery and transplant coordination department was created in 1997 to meet up with the demand of the growing abdominal transplant surgery and organ procurement activity at the University Hospitals in Leuven. Since then, the procurement activity has increased and is currently distributed within the University Hospital Gasthuisberg and a network of ~25 collaborative hospitals. The profile of the donors has changed with older donors and more co-morbidity factors (obesity, hypertension, etc.). This donor activity represents ~30% of the national donor pool. Over the last 10 years, more than 1100 kidneys, more than 500 livers, ~50 pancreas, and 5 intestines have been transplanted in both adults and children. One year survival equal to-or exceeding 90% has been achieved for all abdominal organs and this compares favorably with international registries. More than 40 multi-visceral transplants {liver in combination with abdominal (kidney, pancreas, intestine) or thoracic (heart, double lung, heart-lung) organs} have been performed with results equivalent to isolated liver transplants and very little immunological graft loss (probably due to the immunoprotective effect of the liver). A live donation program was started for the kidney (40 cases) and for the liver (10 cases) in adults and children and no surgical graft loss has been seen so far. Introduction of new machine perfusion systems (and development of donor protocols) has made it possible to restart a non-heart-beating donor program for kidney transplantation. Experimental demonstration that livers tolerate short periods of warm ischemia has also allowed to start liver transplantation from non-heart-beating donors. In the future, machine perfusion of livers, viability testing, and biological modulation are likely to widen the use of marginal livers for transplantation and improve the results. An immunomodulatory protocol proven in the lab to induce the development of regulatory T cells has been applied clinically to 5 consecutive intestinal transplants. All 5 - at the time of writing - have been rejection-free and have achieved nutritional independence. Continuous research and development is warranted to increase the organ donor pool (currently the solely limiting factor of transplantation) and to optimize long-term graft and patient outcome.

Improved Kidney Graft Function After Preservation Using a Novel Hypothermic Machine Perfusion Device

To study graft function and ischemia/reperfusion injury of porcine kidneys after preservation with the new Groningen Machine Perfusion (GMP) system versus static cold storage (CS). The increasing proportion of marginal and nonheart beating donors necessitates better preservation methods to maintain adequate graft viability. Hypothermic machine preservation (HMP) is a promising alternative to static CS. We have therefore developed and tested an HMP device, which is portable and actively oxygenates the perfusate via an oxygenator. The aim of the present study was to examine the efficacy of the GMP system in a transplantation experiment. In a porcine autotransplantation model, kidneys were retrieved and either cold stored in University of Wisconsin CS for 20 hours at 4 degrees C or subjected to HMP using University of Wisconsin machine perfusion at 4 degrees C with 2 different pressure settings: 30/20 mm Hg or 60/40 mm Hg. HMP at 30/20 mm Hg was found to better preserve the viability of kidneys reflected by improved cortical microcirculation, less damage to the proximal tubule, less damage mediated by reactive oxygen species, less proinflammatory cytokine expression, and better functional recovery after transplantation. However, high perfusion pressures (60/40 mm Hg) resulted in higher expression of von Willebrand factor and monocyte chemotactic peptide-1 in postpreservation biopsies and subsequent graft thrombosis in 2 kidneys. It is concluded that the GMP system improves kidney graft viability and perfusion pressures are critically important for outcome.

Hemodynamic, Biochemical, and Morphological Characteristics During Preservation of Normal Porcine Livers by Hypothermic Machine Perfusion

In renal transplantation, hypothermic machine perfusion optimizes preservation of marginal grafts, assesses their quality prior to transplantation, improves outcome, and may contribute to an increased number of transplantations. Recently, hypothermic machine perfusion has become increasingly popular given the organ shortage and the “obligatory” utilization of marginal organs. Increasing mortality on the liver transplantation waiting list makes it urgent to develop machine perfusion systems for livers, trying to better preserve marginal livers and perhaps to recover currently discarded livers are for clinical transplantation without an increased risk of graft nonfunction. However, data on machine perfusion of livers and perfusion parameters capable of predicting viability are scarce. The aim of this study was to determine the baseline hemodynamic and metabolic profiles and morphology of livers during hypothermic machine perfusion in a porcine model. We used protocol similar to hypothermic machine perfusion of kidneys. Hemodynamic analysis revealed higher vascular resistance in the hepatic artery versus the portal vein. The arterial resistance gradually decreased during perfusion (similar to kidneys), suggesting progressive relaxation of the arterial vasculature, and perhaps better penetration of the microcirculation by the perfusion solution. During hypothermic machine perfusion, transaminases were gradually (but modestly) released, and livers displayed unequivocal signs of aerobic and anaerobic metabolism. After 24 hours, livers appeared morphologically well preserved. In conclusion, this study showed that hypothermic machine perfusion was feasible. During hypothermic machine perfusion, was easily assessed hemodynamic, biochemical, and morphological parameters.

Machine perfusion preservation of the liver: a worthwhile clinical activity?

Although successful machine perfusion procedures of the liver were first performed almost four decades ago, technical and logistical constraints have prevented general acceptance. Interest in the procedure has recently been renewed due to its potential to resuscitate marginal organs. This review describes experimental and clinical liver hypothermic machine perfusion studies and current developments. Experimental studies have shown that oxygenated hypothermic machine perfusion provides a complete washout and can restore parenchymal energy status, a phenomenon of particular importance in preservation of livers from compromised donors. Additionally, perfusion of the hepatic artery can prevent ischemic-type biliary lesions. Short-term and continuous hypothermic machine perfusion prior to or after cold storage preservation have proven more effective than cold storage alone. The benefits of hypothermic machine perfusion for both heart-beating and nonheart-beating liver grafts seem promising in terms of expanding the donor pool. As liver hypothermic machine perfusion systems are not yet commercially available, the process is currently only clinically used for kidney grafts. Clinical application appears feasible in the near future as new, easy-to-use systems and solutions are currently under development.

Improved preservation of fatty liver by machine perfusion at 20 °C respect to conventional cold storage: Biochemical, histochemical and ultrastructural approaches

Donor scarcity stimulated the development of strategies to increase the organ pool for transplantation by accepting fatty livers which are usually rejected. Zucker rats (ZR) are models of hepatic steatosis. A machine perfusion (MP) system with recirculation of an oxygenated medium at 20°C was developed that proved to afford a good protection of normal rat liver. The device was tested on the liver of fat Zucker rat.

Novel short-term hypothermic oxygenated perfusion (HOPE) system prevents injury in rat liver graft from non-heart beating donor.

To assess a machine perfusion system in rescuing liver grafts from non-heart-beating donors (NHBD). The introduction of extracorporeal liver perfusion systems in the clinical routine depends on feasibility. Conceivably, perfusion could be performed during recipient preparation. We investigated whether a novel rat liver machine perfusion applied after in situ ischemia and cold storage can rescue NHBD liver grafts. We induced cardiac arrest in male Brown Norway rats by phrenotomy and ligation of the subcardial aorta. We studied 2 experimental groups: 45 minutes of warm in situ ischemia + 5 hours cold storage versus 45 minutes of warm in situ ischemia + 5 hours cold storage followed by 1 hour hypothermic oxygenated extracorporeal perfusion (HOPE). In both groups, livers were reperfused in a closed sanguineous isolated liver perfusion device for 3 hours at 37 degrees C. To test the benefit of HOPE on survival, we performed orthotopic liver transplantation in both experimental groups. After cold storage and reperfusion, NHBD livers showed necrosis of hepatocytes, increased release of AST, and decreased bile flow. HOPE improved NHBD livers significantly with a reduction of necrosis, less AST release, and increased bile flow. ATP was severely depleted in cold-stored NHBD livers but restored in livers treated by HOPE. After orthotopic liver transplantation, grafts treated by HOPE demonstrated a significant extension on animal survival. We demonstrate a beneficial effect of HOPE by preventing reperfusion injury in a clinically relevant NHBD model.

The Groningen Hypothermic Liver Perfusion Pump: Functional Evaluation of a New Machine Perfusion System

To improve preservation of donor livers, we have developed a portable hypothermic machine perfusion (HMP) system as an alternative for static cold storage. A prototype of the system was built and evaluated on functionality. Evaluation criteria included 24 h of adequate pressure controlled perfusion, sufficient oxygenation, a maintained 0-4 degrees C temperature and sterile conditions. Porcine livers were perfused with pump pressures that were set at 4 mmHg (continuous, portal vein) and 30/20 mmHg, at 60 BPM (pulsatile, hepatic artery). Control livers were preserved using the clinical golden standard: static cold storage. In the HMP group, pressure, flow and temperature were continuously monitored for 24 h. At time-points t = 0, 2, 4, 8, 12, and 24 h samples of University of Wisconsin machine preservation solution were taken for measurement of partial oxygen pressure (pO(2)) and lacto-dehydrogenase. Biopsies in every lobe were taken for histology and electron microscopy; samples of ice, preservation solution, liver surface, and bile were taken and cultured to determine sterility. Results showed that temperature was maintained at 0-4 degrees C; perfusion pressure was maintained at 4 mmHg and 30/20 mmHg for portal vein and hepatic artery, respectively. Flow was approximately 350 and 80 ml/min, respectively, but decreased in the portal vein, probably due to edema formation. Arterial pO(2) was kept at 100 kPa. Histology showed complete perfusion of the liver with no major damage to hepatocytes, bile ducts, and non-parenchymal cells compared to control livers. The machine perfusion system complied to the design criteria and will have to demonstrate the superiority of machine perfusion over cold storage in transplant experiments.

Pulsatile machine perfusion vs. cold storage of kidneys for transplantation: a rapid and systematic review.

To identify and prioritize key areas for further research in kidney preservation systems. We conducted a systematic review and meta-analysis of the effectiveness of machine perfusion and cold storage techniques in reducing delayed graft function (DGF) and improving graft survival in recipients of kidneys from beating and non-heart-beating donors. Literature quantifying the link between DGF and graft survival was used to evaluate the potential long-term impact of machine perfusion and cold storage systems. Cox proportional hazards modelling was used to predict graft survival and graft years gained over 10 yr. Monte Carlo sensitivity analysis was conducted to evaluate stochastic uncertainties within the model. Machine perfusion leads to a relative risk of DGF of approximately 80% (67%, 96%) compared with cold storage, although the evidence base is limited in quality and study size. Direct evidence on graft survival at 1 yr demonstrates no statistically significant difference between machine perfusion and cold storage. Predictions based upon quantifying the link between DGF and graft survival suggest potential improvements of between 0 and 6% at 10 yr. Studies of high methodological quality and sufficient size are required to determine whether machine preservation leads to reduce rates of DGF. Predicted impact on graft survival implies that direct evidence would require a large population followed up over a long period of time. Registry database analysis supported by validation of the link between DGF and graft survival may be preferable and more feasible than randomized controlled trials.

HYDROGEN IONS EQUILIBRIUM DURING HYPOTHERMIC PULSATILE PERFUSION AND POSTTRANSPLANT KIDNEY FUNCTION.

451 There are many factors that affect post-transplant kidney function and very few of them can be influenced by transplant teams. Hydrogen ions equilibrium within preservation solution during organ machine perfusion definitely belongs to the latter group. Injury to the organ caused by profound acidosis is well known and carefully avoided. However, there is much less concern on alkalinity. While analysing pH of solution during hypothermic perfusion of kidneys, which later underwent acute tubular necrosis (ATN), we surprisingly observed its bimodal distribution. In organs with good immediate function after revascularisation pH values distribution was always normal or close to normal. To analyse this observation, we reviewed 122 perfusion procedures. Material. Organs were preserved with Waters Instr. (MN) MOX 100 machine perfusion system in UW-gluconate solution. Temperature of solution was stabilised at + 6°C and perfusion was begun with 50-mmHg initial systolic pressure at 1 Hz pulse rate. Samples of preservation fluid for hydrogen ions concentration were taken hourly for the first 4 hours and than 4-hourly till the end of perfusion. Abnormalities were corrected with 8,4% NaHCO3, 5M KOH infusions or CO2 insuflation when necessary. Ninety-eight kidneys transplanted after pulsatile preservation functioned immediately. Forty-four had ATN defined as requirement of at least 1 hemodialysis within the first week. Four kidneys never functioned, 2 patients died in short postoperative period and 6 kidneys were discarded due to perfusion parameters, organ trauma, hipoplasia or infection. Results. Mean pH values in established time-points have been calculated for kidneys with immediate function: (Table) As distribution of the values was normal, the range, which covered 95,46% of the area (mean ±2SD), was calculated. None of the preservation solutions from organs with delayed function (DF) exceeded calculated range until 8th hour of perfusion. From 8th hour alkalosis of two solutions was observed (pH=7.52 and 7.58). Only one solution from DF group became too acidic in 24th hour (pH=6,95).TableConclusions. In 3 above mentioned cases improper preservation could be a reason, or at least add to organ damage and posttransplant ATN. Alkalosis of preservation solution can be as harmful to the organ as profound acidosis. Frequent pH measures (1-hourly) urge perfusionist's reaction and prevent accidental long-lasting disturbances of hydrogen equilibrium. One should control pH of the solution to keep it between 6,99-7,35 during perfusion.