Methods of renal preservation

Organ storage in renal transplantation

PURPOSE OF REVIEW

Kidney transplantation is vital for those with end-stage renal disease, enhancing quality of life and longevity. It is the preferred treatment but is hindered by a global disparity between donor kidney availability and demand. Therefore, optimizing organ storage techniques is crucial to mitigate the effects of ischemia reperfusion injury in available organs. Recent interest has centered on innovative methods like oxygenated normothermic perfusion and abdominal regional perfusion.

RECENT FINDINGS

Multiple recent metanalyses, including a Cochrane review, confirm the benefits of hypothermic machine perfusion (HMP) for deceased donor kidneys, demonstrating its utility and cost effectiveness. The benefits of oxygenated normothermic perfusion have been seen in retrospective data sets but not in prospective trials. Abdominal regional perfusion (aNRP) is gaining interest, especially for liver transplantation, but kidney specific data are scant.

SUMMARY

High-quality evidence backs the use of HMP for deceased donor kidneys. Despite interest in other techniques, clinical evidence for their benefits in kidney transplantation is lacking. The gap between innovation and verified success emphasizes the need for continued research and collaboration between medical professionals, researchers, and ethical committees. This review aims to further illuminate the complexities and advancements in the field, bridging the knowledge gap and aiding in the continual pursuit of excellence in transplantation.

Normothermic versus hypothermic ex vivo flush using a novel phosphate-free preservation solution (AQIX) in porcine kidneys

BACKGROUND

The initial flush of an organ is important to remove any cellular components from the microcirculation before storage. The aim of this study was to assess graft function after an ex vivo warm flush with a novel non-phosphate buffered preservation solution AQIX RS-I (AQIX) compared with a traditional cold flush.

METHODS

Porcine kidneys were either warm-flushed with AQIX RS-I at 30°C, or cold-flushed at 4°C with University of Wisconsin solution (UW) or hyperosmolar citrate (HOC) preservation solution at a pressure of 100 cmH2O (n = 6). Renal function was measured ex vivo by perfusing the organs with autologous blood at 37°C on an isolated organ perfusion system.

RESULTS

The AQIX group flushed significantly quicker than the cold stored groups (22 ± 1.8 versus UW 4.9 ± 1.6 versus HOC 10 ± 1.6 mL/min/100g; P = 0.001) and gained less weight than the UW group (19 ± 2.9 versus UW 30 ± 3.4 versus HOC 21% ± 7.7%; P = 0.025). The AQIX group also had superior acid-base homeostasis. Functional results, histologic analysis, and ADP: ATP levels were comparable between the groups.

CONCLUSION

Flushing kidneys with AQIX at 30°C cleared the renal microcirculation of blood more rapidly without any detrimental effects when compared to traditional cold flushing with UW or HOC at 4°C. Warm initial flushing has potential to be developed as part of normothermic renal preservation techniques.

A Comparison of Renal Preservation by Cold Storage and Machine Perfusion Using a Porcine Autotransplant Model

BACKGROUND

Pulsatile machine perfusion offers theoretical advantages as a method of preserving kidneys before transplantation. This may be particularly the case for organs taken from non-heart-beating donors (NHBD), but there is still a lack of data to support this view. The aim of this study was to compare the effectiveness of static cold storage in ice (CS) and hypothermic pulsatile machine perfusion (MP) as methods of renal transplant preservation.

METHODS

Groups of large white pigs (n=5) underwent left nephrectomy after warm ischemic times (WIT) of 0 or 30 min. Kidneys were preserved by CS or by cold (3degrees-8degreesC) MP for 24 hr. The left kidney was then autotransplanted into the right iliac fossa and an immediate right nephrectomy was performed. Renal function was assessed daily for 14 days.

RESULTS

Fourteen-day animal survival rates for 0 and 30 min WIT were four of five and one of five after both CS and MP. In the zero WIT groups, there was improved recovery of renal function after MP (area under the creatinine curve, 4,722+/-2,496 [MP] vs. 8,849+/-2,379 [CS]; P<0.05). MP did not improve renal function after 30 min of WIT (mean daily area under the creatinine curve, 1,077+/-145 [MP] vs. 1,049+/-265 [CS]).

CONCLUSIONS

In this model, MP improved 24-hr preservation of kidneys not subjected to warm ischemia (heart-beating donor model), but there was no evidence that MP was a better method of preservation than CS for kidneys exposed to 30 min of WIT (NHBD model).