Transplantation of warm ischemia damaged kidneys: an experimental study in pigs

Effect of Warm Ischemia on Graft Outcome in Laparoscopic Donor Nephrectomy

PURPOSE

To assess the impact of warm ischemia time (WIT) on delayed graft function (DGF), graft loss, and graft function in laparoscopic donor nephrectomy (LDN).

PATIENTS AND METHODS

We prospectively studied 100 kidney recipients from LDN donors from 2001 to 2003. For comparison of graft outcome with different extents of WIT, recipients were divided into three groups: group A received kidneys having 4 to 6 minutes, group B kidneys having >6 to 10 minutes, and group C kidneys having >10 minutes of WIT. The median follow-up was 415 days (range 11-791) days.

RESULTS

The mean kidney WIT was 8.7 minutes (range 4-17 minutes). Graft outcome (DGF, graft loss, and median serum creatinine) was not significantly different in the three groups.

CONCLUSIONS

Different extents of WIT in LDN, within the range of our study, were not associated with an adverse outcome in kidney transplantation.

Oxidative stress in chronic renal allograft nephropathy in rats: effects of long-term treatment with carvedilol, BM 91.0228, or alpha-tocopherol

Oxidative stress is markedly increased after kidney transplantation and may participate in the development and/or progression of chronic renal allograft nephropathy. In the present study we sought to assess the nephroprotective potential of antioxidative treatment in renal allograft recipients. Experiments were performed in the Fisher-Lewis rat model of chronic renal allograft nephropathy, with isografted Lewis rats serving as controls. Allografted rats were orally treated with carvedilol, an antihypertensive drug with antioxidative properties (25 mg/kg/d), its purely antioxidative derivative BM 91.0228 (5 mg/kg/d), alpha-tocopherol (100 mg/kg/d), a combination of propranolol/doxazosine (10/5 mg/kg/d), or vehicle for 24 weeks. At the end of the study, oxidative status and influence of antioxidative treatment were assessed in transplanted animals. Chronic allograft nephropathy was characterized by a marked increase of markers for oxidative stress (increased plasma and kidney levels of malondialdehyde, reduced glutathione, and tocopherol levels in renal allografts). Treatment with carvedilol, BM 91.0228, and tocopherol significantly improved antioxidative status of allograft kidney recipients. In addition, carvedilol reduced elevated blood pressure in allografted rats. However none of the drugs had a beneficial influence on functional and morphologic renal changes. Our data thus demonstrate that long-term treatment with the antioxidants carvedilol, BM 91.0228, or alpha-tocopherol does not prevent development of chronic transplant nephropathy, despite an improvement of antioxidative status.

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.

A case-control comparison of the results of renal transplantation from heart-beating and non-heart-beating donors

INTRODUCTION

The decline in heart-beating brainstem dead organ donors has necessitated the search for other organ sources. In the field of renal transplantation one alternative source currently available, but little used, is that of kidneys from non-heart-beating donors (NHBD). Reticence to use NHBD kidneys is in part due to concerns over the effect that warm ischemic may have subsequent graft function. Presented here are the results of the NHBD renal transplants at the Leicester transplant unit, and compared with matched heart-beating donor transplants as a case control analysis.

METHODS

In order to analyze any differences in graft performance between the two organ sources, the confounding effect of other variables known to influence the outcome of renal transplantation was minimized by matching NHBD and HBD transplants for the following criteria: donor age and sex, first or re-transplant, anastomosis and cold times, tissue match and PRA sensitisation. Transplant performance was assessed primarily by graft survival, the statistical evaluation of which was by log rank analysis of Kaplan-Meier curves.

RESULTS

72 NHBD and 192 HBD transplants were performed over an eight year period. Of the 192 HBD transplants, 105 matched one or more of the NHBD by the criteria outlined above, and thus constituted the control group for comparison. There was no significant difference in overall graft survival between the two groups. The 5 year survival for the NHBD was 73% compared with 65% for HBD kidneys. When death with a functioning graft is treated as censored data, then these figures become 75% and 81% respectively, again without statistical significance.

CONCLUSION

NHBD kidneys are a valuable additional source of organs for transplantation, with long-term survival, comparable to transplants from HBD.

Kinetics of cellular viability in warm versus cold ischemia conditions of kidney preservation. A biometric study

We have determined the kinetics of the cellular viability ratio (CVR), defined as the number of living cells over the total cell count, in pig kidneys using propidium iodide and fluorescein diacetate staining, as a function of time and preservation conditions. The kidneys were preserved in warm or cold ischemia in order to mimic the conditions of transplantation from non-heart-beating donors or multiple removal with optimal preservation of the graft, respectively. To determine the CVR, the cells were obtained by a fine-needle aspiration biopsy, which minimizes the damage to the graft. A biometric analysis by regression enabled the determination of the time dependence for warm ischemia (CVR(t) = 80.0 x e(-0.733-t)(+2.7/-0.36)) and for cold ischemia (CVR(t) = 80.0 x e(-0.022-t)(+1.57/-0.64)) with a confidence interval of 95%. These master curves allow us to predict, under the described conditions, the CVR after a given ischemia time. The half-life of the cells can be deduced from the time-dependent CVR(t), and is 0.64 hr (38 min) for warm ischemia and 21.4 hr for cold ischemia. Further, the CVR for a given kidney can be used to assess its condition at removal: if the CVR is below 48% at 2 hr after removal, one can conclude that the organ has suffered a period of warm ischemia.