Machine perfusion and viability assessment of non-heart-beating donor kidneys-a single-centre result

Assessing Kidney Graft Viability and Its Cells Metabolism during Machine Perfusion

Kidney transplantation is the golden treatment for end-stage renal disease. Static cold storage is currently considered the standard method of preservation, but dynamic techniques, such as machine perfusion (MP), have been shown to improve graft function, especially in kidneys donated by extended criteria donors and donation after circulatory death. With poor organ quality being a major reason for kidneys not being transplanted, an accurate, objective and reliable quality assessment during preservation could add value and support to clinicians’ decisions. MPs are emerging technologies with the potential to assess kidney graft viability and quality, both in the hypothermic and normothermic scenarios. The aim of this review is to summarize current tools for graft viability assessment using MP prior to implantation in relation to the ischemic damage.

Maximizing kidneys for transplantation using machine perfusion: from the past to the future: A comprehensive systematic review and meta-analysis

BACKGROUND

The two main options for renal allograft preservation are static cold storage (CS) and machine perfusion (MP). There has been considerably increased interest in MP preservation of kidneys, however conflicting evidence regarding its efficacy and associated costs have impacted its scale of clinical uptake. Additionally, there is no clear consensus regarding oxygenation, and hypo- or normothermia, in conjunction with MP, and its mechanisms of action are also debated. The primary aims of this article were to elucidate the benefits of MP preservation with and without oxygenation, and/or under normothermic conditions, when compared with CS prior to deceased donor kidney transplantation.

METHODS

Clinical (observational studies and prospective trials) and animal (experimental) articles exploring the use of renal MP were assessed (EMBASE, Medline, and Cochrane databases). Meta-analyses were conducted for the comparisons between hypothermic MP (hypothermic machine perfusion [HMP]) and CS (human studies) and normothermic MP (warm (normothermic) perfusion [WP]) compared with CS or HMP (animal studies). The primary outcome was allograft function. Secondary outcomes included graft and patient survival, acute rejection and parameters of tubular, glomerular and endothelial function. Subgroup analyses were conducted in expanded criteria (ECD) and donation after circulatory (DCD) death donors.

RESULTS

A total of 101 studies (63 human and 38 animal) were included. There was a lower rate of delayed graft function in recipients with HMP donor grafts compared with CS kidneys (RR 0.77; 95% CI 0.69-0.87). Primary nonfunction (PNF) was reduced in ECD kidneys preserved by HMP (RR 0.28; 95% CI 0.09-0.89). Renal function in animal studies was significantly better in WP kidneys compared with both HMP (standardized mean difference [SMD] of peak creatinine 1.66; 95% CI 3.19 to 0.14) and CS (SMD of peak creatinine 1.72; 95% CI 3.09 to 0.34). MP improves renal preservation through the better maintenance of tubular, glomerular, and endothelial function and integrity.

CONCLUSIONS

HMP improves short-term outcomes after renal transplantation, with a less clear effect in the longer-term. There is considerable room for modification of the process to assess whether superior outcomes can be achieved through oxygenation, perfusion fluid manipulation, and alteration of perfusion temperature. In particular, correlative experimental (animal) data provides strong support for more clinical trials investigating normothermic MP.

Protective effects of hypothermic ex vivo perfusion on ischemia/reperfusion injury and transplant outcomes

Hypothermic machine preservation (HMP) has been used in renal transplantation since the late 1960s with recent robust prospective, multicenter data showing lower rates of delayed graft function and improved graft survival. Although now clearly beneficial for renal transplantation, extrarenal machine perfusion has remained predominantly in preclinical investigations. Pancreatic HMP has drawn little clinical interest because HMP has been suggested to cause graft edema and congestion, which is associated with early venous thrombosis and graft failure. Early investigation showed no benefit of HMP in whole-organ pancreas transplant. One report did show that HMP increases islet cell yield after isolation. Preclinical work in liver HMP has been promising. Short- and long-term HMP has been shown to improve graft viability and reduce preservation injury, even in animal models of steatotic and donation after cardiac death. The first clinical study of liver HMP using a centrifugal dual perfusion technique showed excellent results with lower hepatocellular injury markers and no adverse perfusion-related outcomes. In addition, a dramatic attenuation of proinflammatory cytokine expression was observed. Further studies of liver HMP are planned with focus on developing a reproducible and standard protocol that will allow the widespread availability of this technology. Future research and clinical trials of novel organ preservation techniques, solutions, and interventions are likely to bring about developments that will allow further reduction of preservation-related ischemia/reperfusion injury and improved outcomes and allow safer utilization of the precious and limited resource of donor organs.

Peritoneal cooling may provide improved protection for uncontrolled donors after cardiac death: an exploratory porcine study

Uncontrolled donation after cardiac death (DCD) renal transplantation relies on rapid establishment of organ preservation interventions. We have developed a model of the uncontrolled DCD, comparing current in situ perfusion (ISP) techniques with additional peritoneal cooling (PC). Ten pigs were killed and subjected to a 2 h ischemia period. The ISP group modeled current DCD protocols. The PC group (PC) modeled current protocols plus PC. Two animals were used as controls and subjected to 2 h of warm ischemia. Core renal temperature and microdialysis markers of ischemia were measured. Preservation interventions began at 30 min, with rapid laparotomy and kidney recovery performed at 2 h, prior to machine perfusion viability testing. The final mean renal temperature achieved in the ISP group was 26.3 degrees C versus 16.9 degrees C in the PC group (p = 0.0001). A significant cryopreservation benefit was suggested by lower peak microdialysate lactate and glycerol levels (ISP vs. PC, p = 0.0003 and 0.0008), and the superiority of the PC group viability criteria (p = 0.0147). This pilot study has demonstrated significant temperature, ischemia protection and viability assessment benefits with the use of supplementary PC. The data suggests a need for further research to determine the potential for reductions in the rates of ischemia-related clinical phenomena for uncontrolled DCDs.

Assessment of cadaveric organ viability during pulsatile perfusion using infrared imaging

Assessment of pulsatile perfusion (PP) is limited to measurements of flow (V) and resistance (R). We investigated infrared (IR) imaging during PP as a means for precise organ assessment. IR was used to monitor 10 porcine kidneys during 18 hr of PP in an uncontrolled Donation after Cardiac Death model. An IR camera (Lockheed Martin) was focused on the anterior surfaces of the kidneys. The degree of temperature homogeneity was compared with standard measurements of V and R. IR thermal images correlated with V and R (R=0.92, P<0.001). IR detected an increase in homogeneity during PP by comparing standard deviation differences before and after PP (P=0.002), which was not evident by standard measurements of V and R. Finally, IR assessment allowed for measurement of dynamic changes in perfusion.

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.

In defense of the reverence of all life: Heideggerean dissolution of the ethical challenges of organ donation after circulatory determination of death

During the past 50 years since the first successful organ transplant, waiting lists of potential organ recipients have expanded exponentially as supply and demand have been on a collision course. The recovery of organs from patients with circulatory determination of death is one of several effective alternative approaches recommended to reduce the supply-and-demand gap. However, renewed debate ensues regarding the ethical management of the overarching risks, pressures, challenges and conflicts of interest inherent in organ retrieval after circulatory determination of death. In this article, the author claims that through the engagement of a Heideggerean existential phenomenological and hermeneutic framework what are perceived as ethical problems dissolve, including collapse of commitment to the dead donor rule. The author argues for a revisioned socially constructed conceptual and philosophical responsibility of humankind to recognize the limits of bodily finitude, to responsibly use the capacity of the transplantable organs, and to grant enhanced or renewed existence to one with diminished or life-limited capacity; thereby making the locus of ethical concern the donor-recipient as unitary ''life.'' What ethically matters in the life-cycle (life-world) of donor-recipient is the viability of the organs transplanted; thereby granting reverence to all life.

Machine perfusion preservation improves renal allograft survival

Machine perfusion (MP) has been used as the kidney preservation method in our center for over 10 years. The first, small (n = 74) prospective, single-blinded randomized study comparing MP and Cold Storage (CS) showed that the incidence of delayed graft function was higher after CS. There have been no reports in the literature on the effect of storage modality on long-term function of renal allografts. This paper presents an analysis of long-term results of renal transplantation in 415 patients operated on between 1994 and 1999. Of those, 227 kidneys were MP-stored prior to KTx. The control group consisted of 188 CS kidney transplants. Kidneys were not randomized to MP or to CS. Donor demographics, medical and biochemical data, cold ischemia time, HLA match and recipient data were collected. Standard triple-drug immunosuppression was administered to both groups. Mortality, graft survival and incidence of return to hemodialysis treatment were analyzed. Despite longer cold ischemia time and poorer donor hemodynamics in MP group, 5-year Kaplan-Meier graft survival was better in MP-stored than in CS-stored kidneys (68.2% vs. 54.2%, p = 0.02).

CONCLUSION

In this nonrandomized analysis, kidney storage by MP improved graft survival and reduced the number of patients who returned to dialysis.

Non-heart beating organ donation: overview and future perspectives

New indications for organ transplantation combined with a stagnating number of available donor grafts have severely lengthened the waiting list for almost all types of transplantations. This has led to a renewed interest in non-heart beating (NHB) donation, as a possible solution to bridge the gap between supply and demand. In this review, we present an overview of current NHB donation practice, outcome, existing problems and future perspectives. We focus on possible improvements in donor management, recipient care and new methods of organ preservation that may be better suited for these marginal organs. Successful institution of NHB protocols depends on adapting current transplantation practice at all levels, which is one of the greatest challenges for researchers and professionals in this interesting re-emerging field.

The effect of inadequate in situ perfusion in the non heart-beating donor

In situ aortic perfusion in the nonheart-beating donors (NHBD) is an important procedure to reduce primary warm ischaemic injury prior to formal donor organ retrieval. It allows an interim period to obtain donor family consent and theatre preparation. This study describes our experience of inadequate aortic perfusions resulting from difficult aortic cannulations and associated adverse outcome despite reasonable viability tests. Since 1998, all NHBD in our institution are perfused in situ using a double balloon triple lumen (DBTL) catheter inserted through a femoral artery cut-down procedure. The DBTL catheter is positioned with distal occlusive balloon at the aortic bifurcation using the "pull-back" technique, the proximal occlusive balloon lies above the renal arteries. This provides selective aortic perfusion in particular the kidneys. Venous decompression using a femoral vein catheter enables a "two-way infusion system". Pre-transplant viability status of retrieved kidneys is determined by measuring pressure/resistance characteristics to the flow and biochemical markers for ischaemic injury. There were 90 NHBD renal transplants performed from 72 donors. Three renal transplants were carried out from three donors of ineffective in situ perfusion secondary to cannulation difficulties. Femoral cannulation was difficult as a result of extensive atherosclerosis of donor vessels. The comparison of allograft outcome from effective and ineffective in situ perfusion of donors showed high rate of primary nonfunction (PNF) from ineffective perfusion (chi-squared, P < 0.0001). The cases demonstrated poor outcome from ineffective perfusion related to the cannulation difficulties. Therefore a strict policy should be taken in cases where aortic cannulation and perfusion is inadequate, despite pretransplant assessment. In these circumstances, the primary warm ischaemia time should be extended to include this period of ineffective perfusion.

Pulsatile machine perfusion vs. cold storage of kidneys for transplantation: a rapid and systematic review

OBJECTIVE

To identify and prioritize key areas for further research in kidney preservation systems.

MATERIALS AND METHODS

We conducted a systematic review and meta-analysis of the effectiveness of machine perfusion and cold storage techniques in reducing delayed graft function (DGF) and improving graft survival in recipients of kidneys from beating and non-heart-beating donors. Literature quantifying the link between DGF and graft survival was used to evaluate the potential long-term impact of machine perfusion and cold storage systems. Cox proportional hazards modelling was used to predict graft survival and graft years gained over 10 yr. Monte Carlo sensitivity analysis was conducted to evaluate stochastic uncertainties within the model.

RESULTS

Machine perfusion leads to a relative risk of DGF of approximately 80% (67%, 96%) compared with cold storage, although the evidence base is limited in quality and study size. Direct evidence on graft survival at 1 yr demonstrates no statistically significant difference between machine perfusion and cold storage. Predictions based upon quantifying the link between DGF and graft survival suggest potential improvements of between 0 and 6% at 10 yr.

DISCUSSION

Studies of high methodological quality and sufficient size are required to determine whether machine preservation leads to reduce rates of DGF. Predicted impact on graft survival implies that direct evidence would require a large population followed up over a long period of time. Registry database analysis supported by validation of the link between DGF and graft survival may be preferable and more feasible than randomized controlled trials.

Outcome of transplantation using kidneys from controlled (Maastricht category 3) non-heart-beating donors

BACKGROUND

Many renal transplant centres are reluctant to use kidneys from non-heart-beating (NHB) donors because of the high incidence of primary non-function and delayed graft function reported in the literature. Here, we report our favourable experience of using kidneys from Maastricht category 3 donors (controlled NHB donors).

MATERIALS AND METHODS

From January 1996 to June 2002, 42 renal transplants using kidneys from 25 controlled NHB donors were undertaken at our centre. The rates of primary non-function, delayed graft function (DGF), rejection and long-term graft and patient survival were compared with those of 84 recipients of grafts from heart-beating (HB donors) transplanted contemporaneously.

RESULTS

Primary non-function did not occur in recipients of grafts from NHB donors but was seen in two grafts from HB donors. DGF occurred in 21 of 42 (50%) kidneys from NHB donors and 14 of 84 (17%) kidneys from HBD donars (p < 0.001). The acute rejection rates in the two groups were similar (33% for grafts from NHB donors vs. 40% from HB donors). By 1 month after transplantation, there was no significant difference in serum creatinine concentration between the two groups. Over a median follow-up period of 32 months (range 2-75 months), the actuarial graft survival rates at 1, 3 and 5 yr after transplantation were 84, 80 and 74% for recipients of kidneys from NHB donors, compared with 89, 85 and 80% for kidneys from HB donors.

CONCLUSION

Controlled NHB donors are a valuable and under-used source of kidneys for renal transplantation. The outcome for recipients of kidney allografts from category 3 NHB donors is similar to that seen in recipients of grafts from conventional HB cadaveric donors.