BackgroundEx-vivo normothermic perfusion strategies are a promising new instrument in organ transplantation. The perfusion conditions are designed to be protective however the artificial environment can induce a local inflammatory response. The aim of this study was to determine the effect of incorporating a Cytosorb adsorber into an isolated kidney perfusion system.MethodsPorcine kidneys were subjected to 22 h of cold ischaemia then reperfused for 6 h on an ex vivo reperfusion circuit. Pairs of kidneys were randomised to either control (n = 5) or reperfusion with a Cytosorb adsorber (n = 5) integrated into the circuit. Tissue, blood and urine samples were taken for the measurement of inflammation and renal function.ResultsBaseline levels of cytokines (IL-6, TNFα, IL-8, IL-10, IL-1β, IL-1α) were similar between groups. Levels of IL-6 and IL-8 in the perfusate significantly increased during reperfusion in the control group but not in the Cytosorb group (P = 0.023, 0.049). Levels of the other cytokines were numerically lower in the Cytosorb group; however, this did not reach statistical significance. The mean renal blood flow (RBF) was significantly higher in the Cytosorb group (162 ± 53 vs. 120 ± 35 mL/min/100 g; P = 0.022). Perfusate levels of prostaglandin E2 were significantly lower in the Cytosorb group (642 ± 762 vs. 3258 ± 980 pg/mL; P = 0.0001). Levels of prostacyclin were significantly lower in the Cytosorb group at 1, 3 and 6 h of reperfusion (P = 0.008, 0.003, 0.0002). Levels of thromboxane were also significantly lower in the Cytosorb group throughout reperfusion (P = 0.005). Haemoadsorption had no effect on creatinine clearance (P = 0.109).ConclusionHaemoadsorption can reduce the inflammatory response and improve renal blood flow during perfusion. Nonetheless, in this model haemoadsorption had no influence on renal function and this may relate to the broad-spectrum action of the Cytosorb adsorber that also removes potentially important anti-inflammatory mediators.

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Kidney normothermic machine perfusion (NMP) has historically used a 95% O2-5% CO2 gas mixture. Using a porcine model of organ retrieval, NMP, and reperfusion, we tested the hypothesis that reducing perfusate oxygenation ([Formula: see text]) would be detrimental to renal function and cause injury. In the minimal ischemic injury experiment, kidneys sustained 10 min of warm ischemia and 2 h of static cold storage before 1 h of NMP with either 95%, 25%, or 12% O2 with 5% CO2 and N2 balance. In the clinical injury experiment, kidneys with 10-min warm ischemia and 17-h static cold storage underwent 1-h NMP with the above gas combinations or 18-h static cold storage as a control. They were then reperfused with whole blood and 95% O2 for 3 h. Overall, reducing [Formula: see text] did not significantly influence renal function in either experiment. Furthermore, there were no differences in the injury markers urinary neutrophil gelatinase-associated lipocalin or tissue high-motility group box protein 1. In the minimal ischemic injury experiment, a [Formula: see text] of 25% significantly reduced renal blood flow and increased vascular resistance. Oxygen delivery, consumption, and extraction (oxygen extraction ratio) were significantly greater at 95% [Formula: see text]. In the clinical injury experiment, renal blood flow was significantly increased at 25% [Formula: see text] and Na+ excretion decreased. At 95% [Formula: see text], the oxygen content and oxygen extraction ratio were significantly increased. During reperfusion, renal blood flow was significantly increased in the 25% group. The control group pH was significantly decreased compared with the 25% group. Our data suggest that reducing [Formula: see text] during NMP does not have detrimental effects on renal function or markers of injury.

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BackgroundEx vivo perfusion (EVP) is a novel method of preservation. However, optimal perfusion conditions remain undetermined. Reducing the temperature of the perfusate to subnormothermia may be beneficial during EVP and improve early graft function. The aim of this study was to investigate whether subnormothermia would influence the conditioning effect of EVP when compared with normothermic perfusion, and standard cold static storage (CS).MethodsPorcine kidneys underwent static CS for 23 hours followed by 1 hour of EVP using leukocyte-depleted blood at a mean temperature of 32°C or 37°C. After this, kidneys were reperfused with whole autologous blood at 37°C for 3 hours to assess renal function and injury. These were compared with a control group that underwent 24 hours CS.ResultsDuring EVP, kidneys perfused at 37°C had a higher level of renal blood flow and oxygen consumption compared with EVP at 32°C (P = 0.001, 0.002). During reperfusion, 32°C EVP kidneys had lower creatinine clearance and urine output than control (P = 0.023, 0.011) and a higher fractional excretion of sodium, serum potassium, and serum aspartate transaminase than 37°C EVP kidneys (P = 0.01, 0.023, 0.009).ConclusionsTubular and renal functions were better preserved by a near-physiological temperature of 37°C during 1 hour of EVP, when compared to EVP at 32°C or cold storage.

In renal transplantation, ischemia reperfusion injury impairs early graft function and can reduce long term graft survival. Hydrogen has antioxidant and anti-inflammatory properties that can reduce the effects of ischemic injury. The aim of this study was to examine the effects of hydrogen gas administered during reperfusion in a preclinical model of kidney ischemia reperfusion injury. Porcine kidneys underwent 15 min of warm ischemia followed by 22 h of cold ischemia. They were then reperfused for 6 h with whole autologous blood on an ex vivo reperfusion circuit. Paired kidneys were randomized to control (n = 6) (25% oxygen, 5% carbon dioxide, 70% nitrogen) or hydrogen (n = 6) (2% hydrogen, 25% oxygen, 5% carbon dioxide, 68% nitrogen) groups. Tissue, urine, and blood samples were collected at baseline and hourly throughout the reperfusion period. Baseline measurements were similar across groups. Following perfusion, there was no significant difference between control and hydrogen groups in urine output (693 mL vs. 608 mL, P = 0.86), renal blood flow (105.9 vs. 108 mL/min/100g, P = 0.89), acid-base homeostasis, or creatinine clearance. There was a significant increase in cytokine levels from baseline to 6 h in both groups (IL-1β P = 0.002; IL-6 P = 0.004; IL-8 P = 0.002). However, there were no significant differences in levels of inflammatory cytokines (IL1β, IL-6, and IL-8) between the groups. The administration of hydrogen gas did not improve renal function, reduce oxidative damage, or inflammation during the reperfusion of ischemically damaged kidneys.

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