Evaluation of the factors related to early graft function in 90 kidney transplants from non-heart-beating donors

Extracorporeal support: improves donor renal graft function after cardiac death

Donors after cardiac death (DCD) could increase the organ pool. Data supports good long-term renal graft survival. However, DCDs are <10% of deceased donors in the United States, due to delayed graft function, and primary nonfunction. These complications are minimized by extracorporeal support after cardiac death (ECS-DCD). This study assesses immediate and acute renal function from different donor types. DCDs kidneys were recovered by conventional rapid recovery or by ECS, and transplanted into nephrectomized healthy swine. Warm ischemia of 10 and 30 min were evaluated. Swine living donors were controls (LVD). ECS-DCDs were treated with 90 min of perfusion until organ recovery. After procurement, kidneys were cold storage 4-6 h. Renal vascular resistance (RVR), urine output (UO), urine protein concentration (UrPr) and creatinine clearance (CrCl), were collected during 4 h posttransplantation. All grafts functioned with adequate renal blood flow for 4 h. RVR at 4 h posttransplant returned to baseline only in the LVD group (0.36 mmHg/mL/min +/- 0.03). RVR was higher in all DCDs (0.66 mmHg/mL/min +/- 0.13), without differences between them. UO was >50 mL/h in all DCDs, except in DCD-30 (6.8 mL/h +/- 1.7). DCD-30 had lower CrCl (0.9 mL/min +/- 0.2) and higher UrPr >200 mg/dL, compared to other DCDs >10 mL/min and <160 mg/dL, respectively. Normothermic ECS can resuscitate kidneys to transplantable status after 30 min of cardiac arrest/WI.

Enhanced development of caspase-independent cortical cell death during cold storage in kidneys of non-heart-beating donors

BACKGROUND

Understanding the mechanisms of injury associated with cardiac arrest is essential for defining strategies aimed at improving preservation and function of kidneys harvested in non-heart-beating (NHB) donors.

METHODS

We standardized a model of NHB donors in rats and studied the kinetics and types (apoptosis vs. necrosis) of renal cell death developing during cold storage. Using quantitative polymerase chain reaction, immunoblotting, and caspase inhibition, we also studied the molecular pathways regulating renal cell death in this model.

RESULTS

The kinetics and extent of cell death developing in cortical tubules during cold storage were found to be increased in non-heart-beating (NHB) kidneys. Apoptosis of cortical tubules predominated in NHB kidneys exposed to 10 hr of cold storage, whereas necrosis increased after longer periods of cold ischemia. Shortly after cardiac arrest, a rapid up-regulation of Bax and Hsp 70 was found at the protein level in NHB kidneys. After 24 hr of cold storage, induction of Bax was maintained, whereas protein levels of Hsp70 returned to levels comparable to heart-beating (HB) controls. Also, mRNA levels of Bax were found to increase during cold storage in NHB kidneys. Cortical cell death was found to be largely caspase-independent but responsive to hydroxyl-radical scavenging with dimethyl sulfoxide (DMSO).

CONCLUSIONS

Cardiac arrest promotes activation of death-inducing molecules such as Bax and is associated with increased development of caspase-independent renal cell death during cold storage. Developing strategies, such as free radical scavenging, aimed at inhibiting cell death during cold storage, could prove useful for improving preservation of NHB kidneys.

Use of non-heart-beating donors in renal transplantation

The rate of renal transplantation has plateaued and is now limited by the number of donor organs available. In the past all donor kidneys came from living donors or controlled non-heart beating donors. It was not until the introduction of brainstem death criteria that cadaveric heart beating donors became the main source. Recently, there has been renewed interest in non-heart beating donors, who have already suffered cardiorespiratory arrest. Kidneys from these donors have a unique set of problems associated with increased duration of warm ischaemia. To minimise this, the kidneys are cooled in situ using an intra-aortic balloon catheter and are perfused with cold hyperosmolar citrate. Retrieval can then proceed in the normal fashion. Despite a higher level of delayed graft function, the results from non-heart beating renal transplantation are good, with long term function comparable to cadaveric organs. If used safely, they enable significant expansion of the donor pool. Techniques in the future, such as machine perfusion preservation, may further improve the results from non-heart beating programmes.

The use of expanded criteria cadaver and live donor kidneys for transplantation

The use of expanded criteria donors (non-traditional donors) can help lessen the current shortage of kidneys available for transplantation. The use of older donors has accounted for a large measure of the increase in the organ donation rate; however, the most significant factors found to impact on transplant success negatively traditionally have been shown to be extremes of donor age and last-hour urine output. Less significant variables affecting success rates are average systolic blood pressure, terminal serum creatinine, and days of hospitalization. With the appropriate selection of organs from expanded donors, acceptable outcomes can be obtained. When living donors are selected properly, kidneys with anatomic variants without pathologic significance can be used safely. Kidneys with a heightened potential for the development of progressive disease should not be transplanted. Efforts to decrease the cold ischemia time by increasing the use of kidneys from expanded criteria donors may improve the outcome of transplantation further. Advances in surgical techniques, preservation solutions, and methods for predicting eventual long-term renal function in kidneys from expanded donors will be critical in allowing precise selection criteria for kidneys for transplantation, resulting in the optimum use of a scarce and precious resource. Until options such as xenotransplantation become clinically feasible, the challenge will be to identify which donor organs previously considered suboptimal can be used safely to expand the organ donor pool.

Non-heart-beating donors from the streets: an increasing donor pool source

BACKGROUND

Non-heart-beating donors have become a source for organ donation, especially kidneys. The emergency room and the critical care unit are the two sources for this kind of donor. Three years ago, our hospital began a policy of obtaining organs and tissues successfully from subjects who died in the streets.

METHODS

We consider as potential organ donors people who die out-of-hospital, are less than 50 years old, with less than 15 min of asystolia without cardiac massage, with a known etiology of death, and without general contraindications for donating. After death diagnosis, the cadaver is taken to the hospital where an emergency room doctor certifies the death. Afterward, the cadaver is transferred to the operating room where a cardiopulmonary bypass is performed to preserve the organs while the legal aspects of donation go on.

RESULTS

Up to now, 111 cadavers have been taken as non-heart-beating donors; 53 of them have been actual donors. The average time before arrival to the hospital was 68+/-2.64 min, and the average interval between cardiac arrest and the beginning of cardiopulmonary bypass was 111.33+/-7.09 min. We have obtained 105 kidneys, 12 livers, 84 corneas, and 31 pancreata for islets isolation as well as 49 long bones. Seventy-two kidneys were transplanted, with a probability of survival of 83% at 36 months.

CONCLUSIONS

Our experience indicates that it is possible to obtain organs for transplant from donors who die in the streets and are brought to the hospital under strict selection criteria.