Arjan van der Plaats

Improved kidney graft function after preservation using a novel hypothermic machine perfusion device

Objective: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). Introduction: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. Materials and Methods:In a porcine autotransplantation model, kidneys were retrieved and either cold stored in University of Wisconsin CS for 20 hours at 4°C or subjected to HMP using University of Wisconsin machine perfusion at 4°C with 2 different pressure settings: 30/20 mm Hg or 60/40 mm Hg. Results: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. Conclusions:It is concluded that the GMP system improves kidney graft viability and perfusion pressures are critically important for outcome.

Oxygenation during hypothermic rat liver preservation : an in vitro slice study to demonstrate beneficial or toxic oxygenation effects

Hypothermic machine perfusion (HMP) of abdominal organs is shown to be superior compared to cold storage. However, the question remains if oxygenation is required during preservation as oxygen is essential for energy resynthesis but also generates toxic reactive oxygen species (ROS). To determine if oxygenation should be used during HMP, urea‐synthesis rate, adenosine triphosphate (ATP), and generation of ROS were studied in an in vitro model, modeling ischemia‐reperfusion injury. Furthermore, expression of uncoupling protein‐2 (UCP‐2) mRNA was assessed since UCP‐2 is a potentially protective protein against ROS. Rat liver slices were preserved for 0, 24, and 48 hr in University of Wisconsin machine perfusion solution (UW‐MP) with 0%, 21%, or 95% oxygen at 0‐4°C and reperfused for 24 hours. In the 0% and 95% groups, an increase of ROS was found after cold storage in UW‐MP. After slice reperfusion, only the 0% oxygen group showed higher levels. The 0% group showed a lower urea‐synthesis rate as well as lower ATP levels. mRNA upregulation of UCP‐2 was, in contrast to kidney mRNA studies, not observed. In conclusion, oxygenation of UW‐MP gave better results. This study also shows that ROS formation occurs during hypothermic preservation and the liver is not protected by UCP‐2. We conclude that saturation of UW‐MP with 21% oxygen allows optimal preservation results. (Liver Transpl 2005;11:1403–1411.)

Initial Blood Washout During Organ Procurement Determines Liver Injury and Function After Preservation and Reperfusion

Organ procurement is the first step toward effective liver preservation and comprises a thorough washout of blood components from the microvasculature. To study the efficacy of optimal blood washout of the liver, three groups were compared including low‐pressure perfusion with UW‐CSS (12 mmHg, group A), which is the routine method in clinical practice, high‐pressure perfusion with UW‐CSS (100 mmHg, group B) and low‐pressure perfusion with modified UW solution (12 mmHg, group C). After procurement all livers were preserved in original UW‐CSS for 0, 24 or 48 h, followed by reperfusion in oxygenated Williams Medium E for 24 h at 37 °C. Histology results of livers procured in group A, showed good hepatocyte viability but also remaining erythrocytes. However, injury parameters were high and ATP concentrations were low. No functional differences were found. Group B, high pressure, and group C, modified UW‐CSS, both showed better results. High‐pressure washout is preferable since the warm ischemia time during procurement is short. We propose to use high‐pressure UW‐CSS perfusion for the initial blood washout of the donor liver instead of the usually used low‐pressure washout.

Oxygenation during hypothermic rat liver preservation: An in vitro slice study to demonstrate beneficial or toxic oxygenation effects: Oxygenation During Hypothermic Liver Preservation

Hypothermic machine perfusion (HMP) of abdominal organs is shown to be superior compared to cold storage. However, the question remains if oxygenation is required during preservation as oxygen is essential for energy resynthesis but also generates toxic reactive oxygen species (ROS). To determine if oxygenation should be used during HMP, urea‐synthesis rate, adenosine triphosphate (ATP), and generation of ROS were studied in an in vitro model, modeling ischemia‐reperfusion injury. Furthermore, expression of uncoupling protein‐2 (UCP‐2) mRNA was assessed since UCP‐2 is a potentially protective protein against ROS. Rat liver slices were preserved for 0, 24, and 48 hr in University of Wisconsin machine perfusion solution (UW‐MP) with 0%, 21%, or 95% oxygen at 0‐4°C and reperfused for 24 hours. In the 0% and 95% groups, an increase of ROS was found after cold storage in UW‐MP. After slice reperfusion, only the 0% oxygen group showed higher levels. The 0% group showed a lower urea‐synthesis rate as well as lower ATP levels. mRNA upregulation of UCP‐2 was, in contrast to kidney mRNA studies, not observed. In conclusion, oxygenation of UW‐MP gave better results. This study also shows that ROS formation occurs during hypothermic preservation and the liver is not protected by UCP‐2. We conclude that saturation of UW‐MP with 21% oxygen allows optimal preservation results. (Liver Transpl 2005;11:1403–1411.)

Oxygenation during hypothermic rat liver preservation

Hypothermic machine perfusion (HMP) of abdominal organs is shown to be superior compared to cold storage. However, the question remains if oxygenation is required during preservation as oxygen is essential for energy resynthesis but also generates toxic reactive oxygen species (ROS). To determine if oxygenation should be used during HMP, urea‐synthesis rate, adenosine triphosphate (ATP), and generation of ROS were studied in an in vitro model, modeling ischemia‐reperfusion injury. Furthermore, expression of uncoupling protein‐2 (UCP‐2) mRNA was assessed since UCP‐2 is a potentially protective protein against ROS. Rat liver slices were preserved for 0, 24, and 48 hr in University of Wisconsin machine perfusion solution (UW‐MP) with 0%, 21%, or 95% oxygen at 0‐4°C and reperfused for 24 hours. In the 0% and 95% groups, an increase of ROS was found after cold storage in UW‐MP. After slice reperfusion, only the 0% oxygen group showed higher levels. The 0% group showed a lower urea‐synthesis rate as well as lower ATP levels. mRNA upregulation of UCP‐2 was, in contrast to kidney mRNA studies, not observed. In conclusion, oxygenation of UW‐MP gave better results. This study also shows that ROS formation occurs during hypothermic preservation and the liver is not protected by UCP‐2. We conclude that saturation of UW‐MP with 21% oxygen allows optimal preservation results. (Liver Transpl 2005;11:1403–1411.)