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Background. Normothermic machine perfusion (NMP) is a promising modality for marginal donor kidneys. However, little is known about the effects of NMP on causing endothelial glycocalyx (eGC) injury. This study aims to evaluate the effects of NMP on eGC injury in marginal donor kidneys and whether this is affected by perfusion pressures and hematocrits. Methods. Porcine slaughterhouse kidneys (n = 6/group) underwent 35 min of warm ischemia. Thereafter, the kidneys were preserved with oxygenated hypothermic machine perfusion for 3 h. Subsequently, 4 h of NMP was applied using pressure-controlled perfusion with an autologous blood-based solution containing either 12%, 24%, or 36% hematocrit. Pressures of 55, 75, and 95 mm Hg were applied in the 24% group. Perfusate, urine, and biopsy samples were collected to determine both injury and functional parameters. Results. During NMP, hyaluronan levels in the perfusate increased significantly (P < 0.0001). In addition, the positivity of glyco-stained glycocalyx decreased significantly over time, both in the glomeruli (P = 0.024) and peritubular capillaries (P = 0.003). The number of endothelial cells did not change during NMP (P = 0.157), whereas glomerular endothelial expression of vascular endothelial growth factor receptor-2 decreased significantly (P < 0.001). Microthrombi formation was significantly increased after NMP. The use of different pressures and hematocrits did not affect functional parameters during perfusion. Conclusions. NMP is accompanied with eGC and vascular endothelial growth factor receptor-2 loss, without significant loss of endothelial cells. eGC loss was not affected by the different pressures and hematocrits used. It remains unclear whether endothelial injury during NMP has harmful consequences for the transplanted kidney.

Background. Donation after unexpected circulatory death (uDCD) donors are often suggested to increase the number of donor organs. In 2014, a uDCD protocol was implemented in three transplant centers in the Netherlands which unfortunately did not result in additional transplantations. This study was initiated to identify demographic factors influencing the potential success of uDCD programs. Methods. Dutch resuscitation databases covering various demographic regions were analyzed for potential donors. The databases were compared with the uDCD implementation project and successful uDCD programs in Spain, France, and Russia. Results. The resuscitation databases showed that 61% of all resuscitated patients were transferred to an emergency department. Age selection reduced this uDCD potential to 46% with only patients aged 18–65 years deemed eligible. Of these patients, 27% died in the emergency department. The urban region of Amsterdam showed the largest potential in absolute numbers (52 patients/y). Comparison with the uDCD implementation project showed large similarities in the percentage of potential donors; however, in absolute numbers, it showed a much smaller potential. Calculation of the potential per million persons and the extrapolation of the potential based on the international experience revealed the largest potential in urban regions. Conclusions. Implementation of a uDCD program should not only be based on the number of potential donors calculated from resuscitation databases. They show promising potential uDCD percentages for large rural regions and small urban regions; however, actual numbers per hospital are low, leading to insufficient exposure rates. It is, therefore, recommendable to limit uDCD programs to large urban regions.

Background. The onset of brain death (BD) leads to the deterioration of potential donor lungs. Methylprednisolone is considered to increase lung oxygenation capacity and enhance the procurement yield of donor lungs, when applied in situ, during donor management. However, whether BD-induced lung damage is ameliorated upon treatment with methylprednisolone during acellular ex vivo lung perfusion (EVLP), remains unknown. We aimed to investigate whether the quality of lungs from brain-dead donors improves upon methylprednisolone treatment during EVLP. Methods. Rat lungs were randomly assigned to 1 of 3 experimental groups (n = 8/group): (1) healthy, directly procured lungs subjected to EVLP; (2) lungs from brain-dead rats subjected to cold storage and EVLP; and (3) lungs from brain-dead rats subjected to cold storage and EVLP with 40 mg methylprednisolone added to the perfusate. Ventilation and perfusion parameters, histology, edema formation, metabolic profile, and inflammatory status of lungs were investigated. Results. Methylprednisolone treated lungs from brain-dead donors improved positive inspiratory pressures needed to maintain tidal volumes of 7 mL/kg of body weight, which was 25.6 ± 5.8 cm H2O in untreated lungs and 18.0 ± 3.0 cm H2O in methylprednisolone treated lungs, after 6 h EVLP. Furthermore, dynamic lung compliance increased upon methylprednisolone treatment, with values of 0.11 ± 0.05 mL/cm H2O versus 0.18 ± 0.04 mL/cm H2O after 6 h of EVLP. Methylprednisolone treatment ameliorated the amount of lung edema, as corroborated by a reduction of 0.7 in the wet/dry ratio. Although glucose consumption levels were comparable, the BD-induced cumulative lactate production decreased from 0.44 ± 0.26 to 0.11 ± 0.16 mmol/L upon methylprednisolone treatment. Finally, BD-induced inflammatory status was reduced upon methylprednisolone treatment compared to untreated lungs from brain-dead donors, as reflected by lower proinflammatory gene expression levels of IL-1β, IL-6 and MCP-1, and IL-6 perfusate levels. Conclusions. We showed that methylprednisolone treatment during EVLP attenuates BD-induced lung injury.

Background. It remains controversial if arterial perfusion in addition to portal vein perfusion during machine preservation improves liver graft quality. Comparative studies using both techniques are lacking. We studied the impact of using single or dual machine perfusion of donation after circulatory death rat livers. In addition, we analyzed the effect of pulsatile versus continuous arterial flow. Methods. Donation after circulatory death rat livers (n = 18) were preserved by 6 hours cold storage, followed by 1 hour subnormothermic machine perfusion (20°C, pressure of 40/5 mm Hg) and 2 hours ex vivo warm reperfusion (37°C, pressure of 80/11 mm Hg, 9% whole blood). Machine preservation was either through single portal vein perfusion (SP), dual pulsatile (DPP), or dual continuous perfusion (DCP) of the portal vein and hepatic artery. Hydrodynamics, liver function tests, histopathology, and expression of endothelial specific genes were assessed during 2 hours warm reperfusion. Results. At the end of reperfusion, arterial flow in DPP livers tended to be higher compared to DCP and SP grafts. However, this difference was not significant nor was better flow associated with better outcome. No differences in bile production or alanine aminotransferase levels were observed. SP livers had significantly lower lactate compared to DCP, but not DPP livers. Levels of Caspase-3 and tumor necrosis factor-α were similar between the groups. Expression of endothelial genes Krüppel-like-factor 2 and endothelial nitric oxide synthase tended to be higher in dual perfused livers, but no histological evidence of better preservation of the biliary endothelium or vasculature of the hepatic artery was observed. Conclusions. This study shows comparable outcomes after using a dual or single perfusion approach during end-ischemic subnormothermic liver machine preservation.