Mark-Hugo J. Maathuis

Perspectives in organ preservation

Maintaining organ viability after donation until transplantation is critically important for optimal graft function and survival. To date, static cold storage is the most widely used form of preservation in every day clinical practice. Although simple and effective, it is questionable whether this method is able to prevent deterioration of organ quality in the present era with increasing numbers of organs retrieved from older, more marginal, and even non-heart-beating donors. This review describes principles involved in effective preservation and focuses on some basic components and methods of abdominal organ preservation in clinical and experimental transplantation. Concepts and developments to reduce ischemia related injury are discussed, including hypothermic machine perfusion. Despite the fact that hypothermic machine perfusion might be superior to static cold storage preservation, organs are still exposed to hypothermia induced damage. Therefore, recently some groups have pointed at the beneficial effects of normothermic machine perfusion as a new perspective in organ preservation and transplantation.

Superior Preservation of DCD Livers With Continuous Normothermic Perfusion

Objective:Unexpected donation after cardiac death (DCD) donors suffer cardiac arrest suddenly and are maintained with normothermic extracorporeal membrane oxygenation (NECMO) while consent for donation is obtained. The objective of this study was to determine whether ex vivo normothermic machine perfusion (NMP) improves upon the benefits of NECMO in a large-animal model of unexpected DCD liver transplant. Methods:Donor pigs underwent 90-minute cardiac arrest and were divided in to 3 groups. In the first, livers were preserved immediately with cold storage (CS, n = 6). In the other 2 groups, donors underwent 60-minute NECMO followed by CS (NECMO+CS, n = 6) or NMP (NECMO+NMP, n = 6). After 4–hour preservation, livers were transplanted into recipient pigs. Results:Five-day survival was 0 in CS, 83% in NECMO+CS, and 100% in NECMO+NMP. After reperfusion, injury, and inflammatory markers rose significantly among CS grafts, all of which developed primary nonfunction. Sixty minutes of NECMO, however, resulted in only 1 death, whereas NECMO followed by NMP led to no deaths and significant improvements in injury, inflammation, and synthetic function in comparison to NECMO and CS. Conclusion:Although 60 minutes recuperative NECMO is better than CS alone, NMP improves further on NECMO and may have a role in preserving DCD livers in the clinical setting.

Machine perfusion versus cold storage for preservation of kidneys from expanded criteria donors after brain death.

The purpose of this study was to analyze the possible effects of machine perfusion (MP) versus cold storage (CS) on delayed graft function (DGF) and early graft survival in expanded criteria donor kidneys (ECD). As part of the previously reported international randomized controlled trial 91 consecutive heart‐beating deceased ECDs – defined according to the United Network of Organ Sharing definition – were included in the study. From each donor one kidney was randomized to MP and the contralateral kidney to CS. All recipients were followed for 1 year. The primary endpoint was DGF. Secondary endpoints included primary nonfunction and graft survival. DGF occurred in 27 patients in the CS group (29.7%) and in 20 patients in the MP group (22%). Using the logistic regression model MP significantly reduced the risk of DGF compared with CS (OR 0.460, P = 0.047). The incidence of nonfunction in the CS group (12%) was four times higher than in the MP group (3%) (P = 0.04). One‐year graft survival was significantly higher in machine perfused kidneys compared with cold stored kidneys (92.3% vs. 80.2%, P = 0.02). In the present study, MP preservation clearly reduced the risk of DGF and improved 1‐year graft survival and function in ECD kidneys.

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.

Hypothermic Oxygenated Machine Perfusion in Porcine Donation After Circulatory Determination of Death Liver Transplant

Background Livers from donation after circulatory determination-of-death (DCD) donors suffer ischemic injury during a preextraction period of cardiac arrest and are infrequently used for transplantation; they have the potential, however, to considerably expand the donor pool. We aimed to determine whether hypothermic oxygenated machine perfusion would improve or further deteriorate the quality of these livers using a clinically relevant porcine model. Methods Donor livers were subjected to 90 min of cardiac arrest and preserved at 4°C with either static cold storage using University of Wisconsin solution (CS, n=6) or oxygenated machine perfusion using University of Wisconsin machine perfusion solution and 25% physiological perfusion pressures (HMP, n=5). After 4 hr of preservation, livers were transplanted into recipient pigs, which were followed intensively for up to 5 days. Results Five-day survival was 0 in CS and 20% in HMP. Immediately after reperfusion, hepatocellular injury and function were improved in HMP versus CS. However, HMP grafts also demonstrated significant endothelial and Kupffer cell injury, and a progressive lesion developed 24 to 48 hr after reperfusion that led to death in all but one of the recipient animals. Conclusions Although hypothermic oxygenated machine perfusion performed using subphysiological perfusion pressures seems to offer some advantages over cold storage in the preservation of ischemically damaged livers, it simultaneously conditions endothelial and Kupffer cell injury that may ultimately lead to the failure of these grafts.

Acute Isovolemic Hemodilution Triggers Proinflammatory and Procoagulatory Endothelial Activation in Vital Organs: Role of Erythrocyte Aggregation

Objectives: The essential role of erythrocytes as oxygen carriers is historically well established, but their function to aggregate and the consequences on the microcirculation is under debate. The pathogenic potential of low erythrocyte aggregation could be important for patients undergoing on‐pump cardipopulmonary bypass. These patients are severely hemodiluted due to preoperative isovolemic hemodilution (IHD), circuit priming, and large fluid infusions perioperatively. Considering the vascular endothelium sensitivity to variations in blood rheology, the authors hypothesize that low erythrocyte aggregation will be responsible for activation of vascular endothelium during acute IHD.

Deterioration of Endothelial and Smooth Muscle Cell Function in DCD Kidneys After Static Cold Storage in IGL-1 or UW

BACKGROUND Kidneys obtained from donors after cardiac death are damaged by the combination of warm and cold ischemia. Although the parenchymal damage of these kidneys is well studied, little is known about the functional effects of warm and cold ischemia on the renal vascular bed. We compared kidney preservation using the new extracellular-type cold storage solution from Institut Georges Lopez (IGL-1) with the University of Wisconsin solution (UW) and focused on vasomotor functions. METHODS The influence of warm and cold ischemia on vasomotor functions was studied in an isolated perfused kidney model. Six groups of donation after cardiac death donor kidneys were studied with warm ischemia of 0, 15, and 30 min followed by 0 or 24 h cold storage preservation in IGL-1 or UW at 4 degrees C. Endothelial dependent vasodilation was studied using acetylcholine, smooth muscle cell (SMC) constriction was assessed using phenylephrine, and finally endothelial independent relaxation was tested using papaverine-sulfate. RESULTS SMCs were significantly affected by cold ischemia showing a 50% reduction of phenylephrine mediated constriction after preservation. Additional warm ischemia did not affect SMCs. After UW preservation endothelial dependent vasodilation was only significantly reduced when the combination of warm and cold ischemia was present. IGL-1 preserved kidneys showed a reduction in endothelial dependent vasodilation after isolated warm ischemia. Both preservation solutions rendered equal results after 24 h preservation. CONCLUSION Vasomotor functions are negatively influenced by the combination of warm and cold ischemia. Both IGL-1 and UW performed equally in preserving vasomotor functions. The interesting finding of the rapid decline of SMC function might point at the first step toward intimal hyperplasia as seen in late transplant dysfunction.

Static cold storage preservation of ischemically damaged kidneys. a comparison between IGL-1 and UW solution.

Especially in damaged organs, adequate organ preservation is critically important to maintain viability. Institut Georges Lopez‐1 (IGL‐1) is a new preservation solution, with an extracellular sodium/potassium ratio and polyethylene glycol as a colloid. The influence of warm and cold ischemia was evaluated in a rat Lewis–Lewis transplant model with a follow up of 14 days. Eight groups of donation after cardiac death donor kidneys were studied with warm ischemia of 0 and 15 min followed by 0‐ or 24‐h cold storage (CS) preservation in IGL‐1 or UW‐CSS. Blood was collected daily during the first week and at day 14. Recipients were placed in metabolic cages at day 4 and 14 after transplantation allowing urine collection and adequate measurement of glomerular filtration rate. Focussing on inflammation, reactive oxygen species production, proximal tubule damage, proteinuria, histology, and renal function after transplantation we could not show any relevant difference between IGL‐1 and UW‐CSS. Furthermore, the combination of 15‐min warm ischemia and by 24‐h cold ischemia did not result in life sustaining kidney function after transplantation, irrespective of the used solution. In the present experiment, static CS preservation of ischemically damaged rat kidneys in either IGL‐1 or UW‐CSS rendered equal results after transplantation.