Normothermic organ preservation

Hepatic steatosis and normothermic perfusion-preliminary experiments in a porcine model

BACKGROUND

Steatotic livers are increasingly common in the donor population. Cold storage of steatotic livers exacerbates ischemia-reperfuson injury and risks primary nonfunction and recipient death. Normothermic preservation avoids prolonged cooling of the organ and may be well suited to the preservation and resuscitation of damaged livers. By ex vivo normothermic perfusion, it may be possible to preserve and improve steatotic livers, so that transplantation is a viable option.

METHODS

In a porcine model, streptozotocin was used to induce a hyperglycemic, ketotic state that, together with a high fat diet, resulted in mild hepatic steatosis at 5 weeks. A blood-based oxygenated ex vivo normothermic preservation system was then used to compare extended preservation of normal and mildly steatotic porcine livers at physiological pressures and flows. Serial liver biopsies were stained with Oil Red O, a specialist triglyceride stain, and were analyzed using custom-designed image analysis to quantify the degree of lipid deposition.

RESULTS

Steatotic livers were capable of correcting the perfusate base excess and maintaining factor V and bile production and showed markers of liver injury comparable with normal livers. Steatotic livers had a significantly higher urea production and required no glucose support. Preliminary results suggest that prolonged normothermic perfusion results in a reduction in steatosis.

CONCLUSIONS

This study suggests that steatotic livers can be successfully preserved using normothermic preservation for prolonged periods and that normothermic preservation facilitates a reduction in hepatic steatosis. Further studies are now needed including transplantation of steatotic livers after normothermic preservation.

Rehabilitation of ischemically damaged human kidneys by normothermic extracorporal hemoperfusion in situ with oxygenation and leukocyte depletion

The potential use of donors after cardiac death is an important issue. The crucial point in uncontrolled donors after cardiac death is the warm ischemic time. Definition of the limit of warm ischemic time was 1 of our tasks; an other was to develop a preservation protocol. Five uncontrolled donors kidneys with warm ischemia times up to 80 minutes were exposed to an extracorporal perfusion device for preservation after ischemic damage. We sought to eliminate leukocytes as the main damaging factor in modified donor blood circulating in the device. Recipients of 8 kidneys from this protocol displayed immediate graft function with an average serum creatinine value of 140 +/- 37.9 mmol/L at the end of the second month. Treatment of ischemically damaged kidneys by normothermic extracorporal perfusion with leukocyte depletion before procurement demands further study.

Kidney from uncontrolled donors after cardiac death with one hour warm ischemic time: resuscitation by extracorporal normothermic abdominal perfusion "in situ" by leukocytes-free oxygenated blood

The availability of brain death donors is restricted by many factors. Use of uncontrolled donors after cardiac death could be a promising perspective, but the limiting factor in uncontrolled donation after cardiac death is the warm ischemic time. The purpose of our work was to develop an in situ kidney preservation protocol with application of the extracorporal normothermic abdominal perfusion for organ resuscitation in uncontrolled donors after cardiac death. The main attention was paid to the elimination of leukocytes as the key damaging factor from modified donor oxygenated blood circulating in the device. In 2009, we had 10 uncontrolled donors with warm ischemic time from 45 to 92 min; a normothermic extracorporal perfusion device was applied, providing preservation and restoration of kidney after ischemic damage. In 6 out of 20 kidney recipients, graft function was recovered immediately. All kidney grafts are functioning, and to the end of the third month, the average creatinine was 118.5 ± 19.9 mM. Treatment of ischemically damaged kidney by normothermic extracorporal perfusion with leukocyte depletion before procurement seems to be a challenging protocol for expanding donors' pool and demands further study.

The use of in-situ normothermic extracorporeal perfusion and leukocyte depletion for resuscitation of human donor kidneys

The unexploited potential of donors after cardiac death is an actual issue for all countries where organ transplantation is performed. The crucial point in uncontrolled donation after cardiac death is the warm ischemic time. The primary purpose of our work was to define the limits of warm ischemic time. Another purpose was the development of an in situ kidney preservation protocol. In 8 uncontrolled donors with warm ischemic time from 45 to 91 minutes, a normothermic extracorporeal perfusion device was applied, providing preservation and restoration of the kidney after ischemic damage. Main attention was paid to the elimination of leukocytes as the key damaging factor from modified donor blood circulating in the device. In 6 out of 16 kidney recipients, graft function was recovered immediately and, by the end of the third month, the average creatinine was 117.9±21.9 mmol/L. Treatment of ischemically damaged kidneys by normothermic extracorporeal perfusion, with leukocyte depletion before procurement, seems to be a challenging protocol and demands further study. Implementation of perfusion systems in organ procurement practice could lead to a partial solution in the organ deficit problem.

Functional, metabolic, and morphological aspects of continuous, normothermic heart preservation: effects of different preparation and perfusion techniques

Continuous blood perfusion of donor hearts for transplantation has been the focus of an increasing amount of research, but the optimal preparation and perfusion techniques have not been clearly defined. Therefore, we investigated the effectiveness of different preservation strategies using continuous, normothermic heart perfusion after donor heart harvesting. Hearts of 12 pigs were randomly assigned to two groups receiving a constant pressure perfusion in a modified Langendorff system after different preparation techniques. In Group 1, six hearts were arrested with Bretschneider HTK cardioplegia (4 degrees C) and then reperfused with a circulating pressure of 80 to 90 mmHg using leukocyte depleted autologous blood. In Group 2, beating hearts of six pigs were explanted while being perfused, without cardioplegic arrest. Post-harvesting perfusion was similar to Group 1 except for a lower circulating pressure (40-50 mm Hg). At different time points (baseline and 1, 6, and 12 h after reperfusion), myocardial biopsies were taken, and contractility was assessed by measuring the maximum rate of left ventricular pressure rise (Deltap/Deltat (max)). Adenosine triphosphate (ATP) concentration was measured in all biopsies using a bioluminescence technique. Additionally, ultrastructural alterations were investigated using electron microscopy. Hypothermic cardioplegia and a higher reperfusion pressure (Group 1) were associated with an earlier and sharper decline in contractile function and intracellular ATP concentration. Ultrastructural alterations in Group 1 appeared earlier and were more distinctive than in Group 2. Endothelial ultrastructure, in particular, was better preserved in Group 2. Significant alterations were present in both groups after 12 h of perfusion but were more severe in Group 1. Blood perfusion provides protection against severe ischemic damage for a limited time. The use of a lower perfusion pressure, as well as avoiding cardioplegia and hypothermia, led to significantly better and longer preservation of perfused hearts.