Renal transplantation from non—heart-beating donors: opportunities and challenges

Non heart-beating donors in England

When transplantation started all organs were retrieved from patients immediately after cardio-respiratory arrest, i.e. from non heart-beating donors. After the recognition that death resulted from irreversible damage to the brainstem, organ retrieval rapidly switched to patients certified dead after brainstem testing. These heart-beating-donors have become the principal source of organs for transplantation for the last 30 years. The number of heart-beating-donors are declining and this is likely to continue, therefore cadaveric organs from non-heart-beating donor offers a large potential of resources for organ transplantation. The aim of this study is to examine clinical outcomes of non-heart-beating donors in the past 10 years in the UK as an way of decreasing pressure in the huge waiting list for organs transplantation.

Comparison of renal allograft fibrosis after transplantation from heart-beating and non-heart-beating donors

Background

Renal transplants from non-heart-beating donors (NHBDs) yield acceptable function and allograft survival rates in the medium term. However, the long-term results are less certain and there is a paucity of information relating to the development of chronic allograft nephropathy. The aim of this study was to compare allograft fibrosis in kidneys transplanted from NHBDs and conventional heart-beating donors (HBDs).

Methods

A series of 37 NHBD and 75 HBD renal transplants were studied. Protocol renal transplant biopsies were performed at 6 and 12 months after transplantation. Biopsy sections were stained with Sirius red to demonstrate interstitial extracellular matrix. Renal allograft fibrosis was quantified using a computerized image analysis system.

Results

The mean first warm ischaemia time for kidneys from NHBDs was 24 min. A significant delay in graft function occurred in eight of 75 recipients in the HBD group and 31 of 37 in the NHBD group (P < 0·001). There were no significant differences in the level of allograft fibrosis between the two groups at any time point.

Conclusion

Despite high rates of delayed graft function secondary to a prolonged warm ischaemia time, NHBD kidneys do not appear to be more susceptible to the development of renal allograft fibrosis. This study supports the growing body of evidence that kidneys from NHBDs are an acceptable alternative to those from HBDs.

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).

Nonheart-beating kidney donation: current practice and future developments

BACKGROUND

Nonheart-beating kidney donation (NHBD) is gaining acceptance as a method of donor pool expansion. However, a number of practitioners have concerns over rates of delayed graft function, acute rejection, and long-term graft survival. The ethical issues associated with NHBD are complex and may be a further disincentive. Tailored strategies for preservation, viability prediction, and immunosuppression for kidneys from this source have the potential to maximize the number of available organs. This review article presents the current practice of NHBD kidney transplantation, examines the results and draws comparisons with cadaveric kidneys, and explores some areas of potential development.

METHODS

A review of the current literature on NHBD kidney donation was performed.

RESULTS

The renewed interest in NHBD kidneys is driven by a continuing shortfall in available organs. Those centers involved in NHBD report an increase in kidney transplants of the order of 16% to 40% and there is no evidence that the financial costs are higher with NHBDs. The majority of experience comes from Maastricht category 2 NHBDs, where an estimation of warm time is possible. This is generally limited to 40 minutes. There are variations in the technique for kidney preservation prior to retrieval, but most centers use an aortic balloon catheter. Much work has looked at the ideal technique for kidney preservation prior to implantation. Evidence suggests that machine perfusion produces the best initial function rates, decreased use of adjuvant immunotherapy and fewer haemodialysis sessions than static cold storage.

CONCLUSION

Despite being associated with poorer initial graft function, the long-term allograft survival of NHBD kidneys does not differ from the results of transplantation from cadaveric kidneys. Further, serum creatinine levels are generally equivalent. Constant reassessment of the ethical issues is required for donation to be increased while respecting public concerns. Use of viability assessment and tailoring of immune suppression for NHBD kidneys may allow a further increase in donation from this source.

Long-term outcomes of renal transplantation: a result of the original endowment of the donor kidney and the inflammatory response to both alloantigens and injury

Recent data suggest that long-term allograft survival might be affected by two factors. The first is the endowment of the allograft, which consists of two elements: the nephron mass and the ability of these nephrons to repair injuries sustained during the transplant process. The second factor is renal inflammation. Although inflammation is traditionally ascribed to alloreactivity, recent data have shown that there is also a renal inflammatory response to early injury after transplantation, to brain death in the donor, and as part of the maladaptive response to nephron loss. These two factors contribute to the detrimental effects of delayed graft function or acute rejection on the long-term survival seen in most studies, and the beneficial effects of anti-inflammatory agents on the maladaptive response to nephron loss.

Liver transplantation from controlled non-heart-beating donors

BACKGROUND

The use of organs from non-heart-beating donors (NHBDs) has been proposed as one way to increase the donor pool. However, few centers have transplanted livers from NHBDs. We report here the results of 19 liver transplants from controlled NHBDs.

METHODS

From January 1993 through August 1999, 364 liver transplantations were performed from heart-beating donors (HBDs) and 19 liver transplantations were performed from NHBDs. Donor and recipient characteristics, posttransplant complications, and patient and allograft survival were compared.

RESULTS

No differences in hepatic artery, portal vein, or biliary complications were noted between the groups. However, the rate of primary nonfunction was higher in recipients of livers from NHBDs (10.5% vs. 1.3%; P = .04). No difference in patient survival was seen between recipients of NHBDs or HBDs (72.6% vs. 84.8%; P =.36); however, allograft survival was lower in recipients who received livers from NHBDs (53.8% vs. 80.9%; P =.007).

CONCLUSIONS

Liver transplantation from controlled NHBDs results in similar patient survival and post-transplant complications. However, primary nonfunction was higher and allograft survival was less in recipients of livers from NHBDs. The results of liver transplantation from controlled NHBDs are encouraging and should continue to be cautiously pursued as one way to help alleviate the current shortage of donor livers.