22 July 2015 - 25 June 2015  // 

Dion MS et al. BJU Int. 2014 Oct 18. doi: 10.1111/bju.12960. [Epub ahead of print]

This study represents the first of its kind in which the outcomes of paired kidneys maintained with static cold storage (SCS) versus hypothermic machine perfusion (HMP) have been investigated over a long period of time following transplantation.

In total, 202 patients were included in the study. The first kidney of the pair was selected at random to be maintained in SCS and transplanted, while the second kidney in the pair was transplanted at a later date following HMP (initiated immediately following extraction). Doppler ultrasound parameters and 2-year allograft function were determined for both HMP and SCS groups. The resistive indices (calculated by dividing the difference between the peak systolic flow and the end diastolic flow by the peak systolic flow) were recorded in the mean, upper arcuate, lower arcuate and interlobar arteries of each transplanted kidney on post-transplant days 1 and 7.

In the HMP group, kidneys showed resistive indices at 1-week post-transplantation that were markedly lower compared with the SCS group. Day 1 resistive indices were not found to be statistically different between HMP and SCS groups, possibly indicating that HMP assists with gradual renal recovery over the first week. The authors conclude that the observed but not statistically significant increase in restive indices from day 1 to day 7 post-transplant is interesting but caution that recent findings from another study suggest that changes in restive indices may be more indicative of the recipient physiology than the donor organ.

The authors report that their findings provide clear evidence that kidneys maintained with HMP have excellent function compared with those maintained with SCS. Possible mechanisms include flushing of immunogenic solutes such as cytokines, donor-derived neutrophils and dendritic cells. Maintenance of improved tissue hypothermic conditions may also play a role, resulting in reduced oxidative and metabolic stress, somatic cell senescence and minimized vascular injury. Data from this study also suggest that HMP may improve 2-year graft survival in kidneys obtained from DCD.