Normothermic Ex Vivo Kidney Perfusion for the Preservation of Kidney Grafts prior to Transplantation
July 15th, 2015
The severe organ shortage has resulted in increased use of marginal kidney grafts for transplantation. This has triggered interest in alternative storage methods, since marginal grafts especially tolerate cold storage poorly. The technique of normothermic ex vivo kidney perfusion (NEVKP) represents a novel preservation method for kidney grafts prior to transplantation.
The overall goal of this procedure is to preserve a kidney graft under normal thermic physiological conditions, ex vivo prior to transplantation. This is accomplished by first cannulating, the renal vessels from the donor kidney. The graft is then connected to the circuit and perfused under norm themic conditions.
Ultimately, function parameters of injury and histology of the kidney are monitored to determine the suitability of the graft for transplantation. The main advantage of this technique over existing preservation methods like study called storage or hypothermic machine perfusion, is that norm Themic XVE perfusion avoids cold ischemic injury of standard or extended criteria donor grafts prior to transplantation, no, no, no, no, No, no. After completely dissecting the aorta and cava of the donor, pass a ligature around the aorta cranial to the renal branches, followed by the placement of two ligatures cranial to the iliac bifurcation.
Pass a ligature around the cava distally above the iliac bifurcation, and place a tie around the left renal artery. Then free the right kidney from its adherent tissue and dissect the renal vein, artery and ureter. Next, open the diaphragm and administer 1000 international units of heparin per kilogram of donor weight into the heart.
To collect the blood, connect the lines of CPDA bags to the upper left jugular vein catheter. Tie the ligatures at the left renal artery, the aorta and the cava, and place an aortic cannula above the iliac bifurcation to flush. Immediately flush the kidney with HTK solution with a pressure of 100 centimeters H2O cutting the abdominal cava below the renal vein to ensure an optimal flush.
Simultaneously clamp the thoracic cava and collect the blood via the jugular catheter. When the kidney has been completely flushed, retrieve the graft with a segment of the aorta, severing the renal vein, and leaving the ureter long. Then close the cranial end of the aorta with a tie and cannulate the lower end with a one fourth inch by three eighths inch reducer.
Then directly cannulate the renal vein with a one fourth inch by three-eighths inch reducer. Intubate the ureter with an eight millimeter French feeding tube and place the kidney on ice. Before beginning the perfusion, connect the custom made perfusion circuit to the kidney perfusion device.
Next, position the organ chamber on a stand and introduce the venous and arterial tubing through the prepared holes. After securing the tubing, connect the suction tubing to the venous reservoir and position the other end into the chamber to collect the leaking perfusion solution. Using tubing clamps, close the venous and arterial outflow lines and the outflow of the venous reservoir.
Use an infusion pump to replace the produced urine with ringers lactate solution. Throughout the perfusion, depending on the amount of urine produced, use one syringe pump to administer the nutrition and insulin into the venous reservoir, and another to infuse a vasodilator directly into the arterial line nine. Fill the venous reservoir with the perfusion solution at this time as well.
Then to prime the circuit switch on the heart lung machine and activate the pressure temperature level and bubble sensor panels. Activate the data management system to record the data throughout the perfusion and the heating unit. To warm the perfusion solution and the organ chamber to 37 degrees Celsius.
Open the oxygen supply and the tubing clamp behind the venous reservoir to free the centrifugal pump head from air completely. Then start the centrifugal pump on 1000 rounds per minute and move the solution throughout the circuit. Clamping the tube, bypassing the arterial filter to release the air from the arterial filter.
Finally, zero the pressure lines at 125 milliliters of washed erythrocytes and activate the syringe and infusion pumps when the circuit has been primed. Transfer the kidney from the ice to the bedding of the organ chamber and place the urine catheter into the urine collector. After ensuring that the venous and arterial tubes are free of air, plug the connectors to the tubing.
Then close the shortcut between the arterial and venous tubing lines, and set the arterial pressure to 75 millimeters.Mercury. Record the pressures arterial flow, temperature, and presence of bubbles continuously with a data management system, observing the values carefully throughout the perfusion. Record the quantity of urine produced and collect the venous blood and urine samples hourly to monitor the function of the organ during the perfusion obtained venous and arterial blood, gas, aspartate, aminotransferase, and lactate analysis samples as well.
At the end of perfusion, disconnect the tubing from the renal artery and vein. Flush the graft with cold HTK and store the kidney on ice in a sterile organ bag until transplantation. The aim of normal thermic ex vivo kidney perfusion is to ensure that the graft is supplied with sufficient oxygen and nutrition during the perfusion.
Indeed, after the target graft temperature of 37 degrees Celsius is reached via rewarming of the organ. After three hours of storage on ice, the flow values and intrarenal resistance remains stable with a constant physiological pressure of around 70 millimeters mercury throughout the whole perfusion. The quantity of urine production depends mainly on the composition of the perfusion solution.
While the hourly measurements of the venous and arterial partial pressure of oxygen confirm the metabolic activity of the kidney during the perfusion, the pH bicarbonate and electrolytes are also stable and do not require interventions. Real time aspartate, aminotransferase, and lactate measurements serve to monitor the cellular damage. With no increase in these parameters of cell injury observed during the normal thermic ex vivo kidney perfusion period, the osmolarity of the perfusion solution is also stable.
Further, the histology demonstrates minimal changes in the tissue with mild ization and very low rates of apoptosis Once mastered, this technique can be used as an alternative organ preservation method for kidney grafts, providing further options for organ assessment and repair prior to transplantation.
Overview
This article discusses the technique of normothermic ex vivo kidney perfusion (NEVKP) as a novel preservation method for kidney grafts prior to transplantation. NEVKP aims to maintain the kidney under physiological conditions, thereby reducing cold ischemic injury associated with traditional preservation methods.
Key Study Components
Area of Science
- Nephrology
- Transplantation
- Organ preservation techniques
Background
- Organ shortages have led to the use of marginal kidney grafts.
- Marginal grafts are particularly sensitive to cold storage.
- NEVKP offers a potential solution to improve graft viability.
- This method preserves the kidney under normothermic conditions.
Purpose of Study
- To evaluate the effectiveness of NEVKP in preserving kidney grafts.
- To monitor functional parameters and histology of the kidney during perfusion.
- To compare NEVKP with traditional preservation methods.
Methods Used
- Cannulation of renal vessels from the donor kidney.
- Connection to a perfusion circuit under normothermic conditions.
- Monitoring of injury parameters and histological changes.
- Use of a data management system to record perfusion data.
Main Results
- Stable physiological pressure and urine production during perfusion.
- No significant increase in cellular injury markers observed.
- Histological analysis showed minimal tissue changes.
- Oxygen and nutrient supply maintained throughout the procedure.
Conclusions
- NEVKP is a promising method for preserving kidney grafts.
- It effectively reduces cold ischemic injury compared to traditional methods.
- Further studies are needed to optimize the technique for clinical use.
Frequently Asked Questions
Executive Industry Relevance
Normothermic ex vivo kidney perfusion addresses the critical challenge of preserving marginal kidney grafts that are highly susceptible to cold ischemic injury during standard storage. By maintaining physiological conditions, this technique enables functional assessment and potential repair of grafts prior to transplantation, directly supporting go/no-go decisions in organ utilization. It enhances predictive confidence in graft viability, reducing the risk of delayed graft function and improving the efficiency of transplant programs.
Strategic Applications in Biopharma R&D
Early Discovery & Target Validation
- Scientific Value: Enables interrogation of graft function under physiological conditions to validate biomarkers of injury and recovery.
- Operational Value: Provides a reproducible platform for assessing renal parameters such as urine output, pressure stability, and cellular injury markers.
Screening & Assay Development
- Scientific Value: Supports development of standardized perfusion protocols for evaluating graft viability across donor types.
- Operational Value: Facilitates assay readiness through real-time monitoring of metabolic and functional outputs during preservation.
Translational & Preclinical Research
- Scientific Value: Bridges discovery and preclinical validation by maintaining grafts in a disease-relevant, normothermic system.
- Operational Value: Enables risk-adjusted advancement decisions by monitoring injury markers and histology over defined perfusion durations.
Pipeline & Workflow Integration
Normothermic ex vivo kidney perfusion fits within the discovery-to-translational continuum, supporting early graft evaluation and preclinical assessment prior to clinical transplantation.
- Discovery Biology: Supports hypothesis testing of preservation strategies and pathway analysis of ischemia-reperfusion injury.
- Screening: Delivers quantitative, reproducible outputs such as arterial pressure, urine production, and biomarker stability for graft comparison.
- Analytics: Enables continuous monitoring of functional and injury parameters via data management systems to inform preservation efficacy.
- Translational Research: Maintains graft continuity from explant to transplant by simulating physiological conditions, supporting biomarker alignment and functional assessment.
- Enterprise Reuse: Establishes a reusable perfusion platform applicable across donor types and preservation optimization studies.
Operational & Enterprise Impact
- Scientific Value: Predictive confidence in graft function, reduction of mechanistic ambiguity in preservation injury, and target validation of viability biomarkers.
- Operational Value: Standardization of perfusion conditions, reproducibility across grafts, and scalability for multi-graft evaluation.
- Strategic Value: Improved go/no-go decisions, capital efficiency through better organ utilization, and reduced late-stage biological risk in transplantation.
- Portfolio Impact: Risk-based prioritization of marginal grafts and data-driven advancement decisions based on perfusion performance.
Implementation Considerations
- Requires expertise in vascular cannulation, perfusion circuit setup, and physiological monitoring.
- Dependent on instrumentation including perfusion pumps, oxygenators, temperature controls, and data acquisition systems.
- Necessitates cross-team standardization between surgical, perfusion, and analytical teams for consistent protocol execution.
- Involves adaptation considerations for different graft sizes, donor conditions, and perfusion solution compositions.
- Limited by the need for sterile, non-pyrogenic circuits and the complexity of maintaining normothermia over extended periods.
