Quality assessment of human kidneys by ex-vivo normothermic perfusion
Research type
Research Study
Full title
Quality assessment of human kidneys by ex-vivo normothermic perfusion prior to transplantation
IRAS ID
141278
Contact name
Michael Nicholson
Contact email
Sponsor organisation
Cambridge University NHS Foundation Trust and The University of Cambridge
Duration of Study in the UK
5 years, 0 months, 1 days
Research summary
Research Summary
Approximately 10 to 15% of kidneys are donated and surgically retrieved for transplantation but then deemed unsuitable and therefore discarded. The decision not to transplant an organ is made by an experienced Transplant Consultant based on factors such as the history of the donor, the ischaemic interval and quality of the in-situ perfusion. However, many of these kidneys may actually be suitable for transplantation.
Ex-vivo normothermic perfusion (EVNP) is a technique of preservation that involves warming the kidney to normal body temperature with an oxygenated red blood cell based solution. It has been shown to improve the outcome of kidneys from older and marginal donors. It is also a valuable device on which to assess the quality of a kidney before transplantation. Adopting this system to assess the quality of a kidney could potentially allow more kidneys to be transplanted. We aim to assess the quality of kidneys that have been declined for transplantation by other transplant centres through the national allocation system and through the fast-tracking system. If they are deemed suitable they will transplanted into an appropriately matched recipient.Summary of Results
: Approximately 10–15% of kidneys that are donated are declined for transplantation. The reasons for declining a kidney are multifactorial but ultimately, the decision relies on the judgement of experienced transplant consultants which can be subjective.
Ex vivo normothermic machine perfusion (NMP) is a technique of preservation that involves warming the kidney to near-normal body temperature with an oxygenated red blood cell-based solution. The concept is to restore renal function under ideal conditions for a short period before transplantation to reduce injury and improve early graft function. During NMP kidneys can be graded using a quality assessment score (QAS) on the basis of their appearance and perfusion parameters. Kidneys are graded from 1 (indicating the best quality) to 5 (the worst quality). Kidneys with a QAS of 1–3 may be deemed suitable for transplantation.The aim of this study was to examine the potential for NMP to increase the number of transplants by assessing kidneys that would otherwise be discarded.
Twenty two kidneys deemed unsuitable for transplantation and rejected by all transplant centres in the UK were recruited into this study. Sixteen (72%) of these kidneys were transplanted successfully. There was one patient death with a non-functioning kidney. Graft and patient survival was 94% at 12 months.
The majority of kidneys recruited to this study were offered by NHSBT RINTAG through the research pathway after being declined by all other UK centres. The study only recruited 22 out of the proposed 90 kidneys. The research kidneys often had prolonged cold preservation times and excessive injury at the time of offering. Logistics in transporting the kidney within a suitable timeframe, finding a suitable recipient and theatre allocation at short notice was problematic and prevented recruiting a larger number of kidneys. Furthermore, the classification as a ‘research kidney’ often resulted in a delay in allocation and in several cases questionable sterility and inadequate packing in ice.
The majority of recruited kidneys were declined for transplantation due to poor quality cold flushing. This occurs when blood is not completely removed from the kidney at retrieval, which can lead to additional ischaemic damage and obstruction of the small vessels within the kidney. This study has shown that if the cold preservation time is within a reasonable time frame, a high proportion of these kidneys can be assessed and salvaged using NMP technology with good outcomes. The technology can also be used to assess the quality of damaged kidneys that have undergone repair as demonstrated by one case in this study.
In conclusion, NMP can be used to assess the quality and suitability of kidneys for transplantation. This research study led to 16 additional transplants that would otherwise not have taken place. Future studies should ensure that kidneys that are deemed unsuitable for transplantation, particularly due to poor quality cold flushing, should be prioritised for NMP assessment at an available centre as soon as possible. Future research should also aim to extend the duration of NMP so that kidneys can be preserved for longer periods to avoid damage caused by cold preservation.
REC name
East of England - Cambridge South Research Ethics Committee
REC reference
15/EE/0175
Date of REC Opinion
30 Jun 2015
REC opinion
Further Information Favourable Opinion