Determinants of discard of expanded criteria donor kidneys: impact of biopsy and machine perfusion

Long-term results of biopsy-guided selection and allocation of kidneys from older donors in older recipients

In our old-for-old program, we discard or allocate older extended criteria donor kidneys to single (SKT) or dual kidney transplantation (DKT) depending on histological Remuzzi's score in recipients older than 60 years. Here, we analyze the long-term results of this program and try to identify independent predictors of patient and graft survival. Between December 1996 and January 2008, we performed 115 SKT and 88 DKT. Discard rate was 15%. Acute rejection incidence was higher in SKT than in DKT (22.6% vs. 11.4%, p = 0.04). Renal function was better in DKT than in SKT up to 5 years after transplantation. Surgical complications were frequent in DKT. Ten-year cumulative graft survival was significantly lower in the SKT group (31% vs. 53%, p = 0.03). In SKT, histological score 4 provided similar graft survival than 3 or less, whereas in DKT score 4, 5 or 6 displayed similar outcome. Finally, independent predictors of graft survival were history of major adverse cardiac event and 1-year serum creatinine, rather than SKT or DKT. In conclusion, this biopsy-guided old-for-old strategy resulted in acceptable long-term graft survival. Our results suggest that DKT should be considered for scores of 5 or 6 only.

Utilization of kidneys with similar kidney donor risk index values from standard versus expanded criteria donors

With the shortage of standard criteria donor (SCD) kidneys, efficient expanded criteria donor (ECD) kidney utilization has become more vital. We investigated the effects of the ECD label on kidney recovery, utilization and outcomes. Using data from the Scientific Registry of Transplant Recipients from November 2002 to May 2010, we determined recovery and transplant rates, and modeled discard risk, for kidneys within a range of kidney donor risk index (KDRI) 1.4-2.1 that included both SCD and ECD kidneys. To further compare similar quality kidneys, these kidneys were again divided into three KDRI intervals. Overall, ECD kidneys had higher recovery rates, but lower transplant rates. However, within each KDRI interval, SCD and ECD kidneys were transplanted at similar rates. Overall, there was increased risk for discard for biopsied kidneys. SCD kidneys in the lower two KDRI intervals had the highest risk of discard if biopsied. Pumped kidneys had a lower risk of discard, which was modulated by KDRI for SCD kidneys but not ECD kidneys. Although overall ECD graft survival was worse than SCD, there were no differences within individual KDRI intervals. Thus, ECD designation adversely affects neither utilization nor outcomes beyond that predicted by KDRI.

Optimal flow and pressure management in machine perfusion systems for organ preservation

Intra-organ flow is the most critical parameter in machine-perfused organ preservation systems (MPS). Ultrasonic flow sensors (UFS) are commonly employed in MPS. However, UFS are sensitive to changes in fluid composition and temperature and require recalibration. Novel Coriolis-type mass flow sensors (CFS) may be more suitable for MPS because the measurement technique is not amenable to these factors. The effect of viscosity, colloids, temperature, pressure, and preservation solution on flow measurement accuracy of UFS and CFS was therefore investigated. A CFS-based MPS was built and validated for setpoint stability using porcine kidneys and the ability to reproduce different pressure and flow waveforms. The UFS exhibited a temperature- and preservation solution-dependent overestimation of flow rate compared to the CFS. The CFS deviated minimally from the actual flow rate and did not require recalibration. The CFS-based MPS conformed to the preprogrammed temperature, flow, pressure, and vascular resistance settings during 6-h kidney preservation. The system was also able to accurately reproduce different pressure and flow waveforms. Conclusively, CFS-based MPS are more suitable for organ preservation than UFS-based MPS. Our CFS-based MPS provides a versatile yet robust experimental platform for testing and validating different types of clinical and experimental MPS.

With respect to elderly patients: finding kidneys in the context of new allocation concepts

The elderly have benefited from increased access to renal transplantation in recent years. New allocation concepts would shift distribution of kidneys to younger recipients, making expanded criteria and living donor kidneys more relevant for seniors. Current issues impacting expanded criteria donor kidney availability and living donor transplant opportunities for the elderly are explored. It is hoped that the kidney donor profile index will improve risk assessment and utilization of marginal kidneys. The usefulness of procurement biopsy remains controversial. Dual kidney transplantation and machine perfusion appear to be effective mechanisms to increase organ availability. "Old-for-old" allocation systems, donation service area variation and regulatory and reimbursement issues highlight disparities and disincentives affecting expanded criteria donor organ utilization, and considerations for the way forward are discussed. Living donor transplantation, even with older donors, may provide the best option for elderly recipients, and careful expansion of the living donor pool appears appropriate. In light of new allocation concepts, it will be important to understand issues pertinent to seniors and develop effective strategies to maintain or improve their access to the benefits of transplantation.

Deceased-donor kidney perfusate and urine biomarkers for kidney allograft outcomes: a systematic review

BACKGROUND

Accurate and reliable assessment of kidney quality before transplantation is needed to predict recipient outcomes and to optimize management and allocation of the allograft. The aim of this study was to systematically review the published literature on biomarkers in two mediums (the perfusate from deceased-donor kidneys receiving machine perfusion and deceased-donor urine) that were evaluated for their possible association with outcomes after kidney transplantation.

METHODS

We searched the Ovid Medline and Scopus databases using broad keywords related to deceased-donor biomarkers in kidney transplantation (limited to humans and the English language). Studies were included if they involved deceased-donor kidneys, measured perfusate or urine biomarkers and studied a possible relationship between biomarker concentrations and kidney allograft outcomes. Each included article was assessed for methodological quality.

RESULTS

Of 1430 abstracts screened, 29 studies met the inclusion criteria. Of these, 23 were studies of perfusate (16 biomarkers examined) and 6 were studies of urine (18 biomarkers examined). Only 3 studies (two perfusate) met the criteria of 'good' quality and only 12 were published since 2000. Perfusate lactate dehydrogenase, glutathione-S-transferase (GST) and aspartate transaminase were all found to be significantly associated with delayed graft function in a majority of their respective studies (6/9, 4/6 and 2/2 studies, respectively). Urine neutrophil gelatinase-associated lipocalin, GST, Trolox-equivalent antioxidant capacity and kidney injury molecule-1 were found to be significantly associated with allograft outcomes in single studies that examined diverse end points.

CONCLUSION

Higher quality studies are needed to investigate modern kidney injury biomarkers, to validate novel biomarkers in larger donor populations and to determine the incremental predictive value of biomarkers over traditional clinical variables.

Advances in machine perfusion graft viability assessment in kidney, liver, pancreas, lung, and heart transplant

Solid organ transplant constitutes the definitive treatment for end-stage organ failure. Better organ preservation methods have enabled use of marginal grafts, thereby expanding the donor pool to meet the growing demand for organs. Static cold storage as a preservation method has been superseded largely by machine perfusion in kidney transplant, with work regarding its use in other organ transplants ongoing. We hope that machine perfusion will allow better graft preservation, and pretransplant assessment, and optimization. The most extensive laboratory, preclinical, and clinical research into machine perfusion organ preservation has focused on kidneys. Successful outcomes in its use in renal transplant have sparked interest for its development and application to the liver, pancreas, heart, and lungs. This article reviews the current state of machine perfusion in abdominal and thoracic organ transplant, focusing on the recent developments in assessing graft viability.

The aggressive phenotype: center-level patterns in the utilization of suboptimal kidneys

Despite the fact that suboptimal kidneys have worse outcomes, differences in waiting times and wait-list mortality have led to variations in the use of these kidneys. It is unknown whether aggressive center-level use of one type of suboptimal graft clusters with aggressive use of other types of suboptimal grafts, and what center characteristics are associated with an overall aggressive phenotype. United Network for Organ Sharing (UNOS) data from 2005 to 2009 for adult kidney transplant recipients was aggregated to the center level. An aggressiveness score was assigned to each center based on usage of suboptimal grafts. Deceased-donor transplant volume correlated with aggressiveness in lower volume, but not higher volume centers. Aggressive centers were mostly found in regions 2 and 9. Aggressiveness was associated with wait-list size (RR 1.69, 95% CI 1.20-2.34, p = 0.002), organ shortage (RR 2.30, 95% CI 1.57-3.37, p < 0.001) and waiting times (RR 1.75, 95% CI 1.20-2.57, p = 0.004). No centers in single-center OPOs were classified as aggressive. In cluster analysis, the most aggressive centers were aggressive in all metrics and vice versa; however, centers with intermediate aggressiveness had phenotypic patterns in their usage of suboptimal kidneys. In conclusion, wait-list size, waiting times, geographic region and OPO competition seem to be driving factors in center-level aggressiveness.

Peritransplant kidney biopsies: comparison of pathologic interpretations and practice patterns of organ procurement organizations

The preimplantation kidney biopsy affects utilization by diagnosing glomerulosclerosis, interstitial fibrosis (IF), arteriosclerosis, and arteriolar hyalinosis. Organ procurement organizations (OPOs) determine whether a donor warrants this biopsy and the donor hospital pathologists (DHPs) report on an OPO-specific pathology interpretation form. Biopsy slides from 40 deceased donor kidneys transplanted at our institution were used to compare interpretations between our transplant pathologist and the DHPs. Thirty-three of these kidneys also had post-perfusion biopsies (PPB). All 58 OPOs were queried for criteria used to request a preimplantation biopsy, and their pathology interpretation forms were also analyzed. The transplant and DHPs had substantial agreement for percent glomerulosclerosis with 75% of biopsies being interpreted within five percentage points. Concordance for IF was poor. The DHP rarely reported arterial pathology. Seventy percent of preimplantation and PPB were read similarly for glomerulosclerosis; concordance for other lesions was weaker. There were no cues for arterial disease on our OPO's pathology interpretation form. Criteria for obtaining a preimplantation biopsy lacked uniformity for the 21 OPOs with a self-generated policy. The pathology interpretation forms varied widely among the OPOs. Current OPO practices with regard to the preimplantation biopsy should be improved.

Revisiting double kidney transplantation: two kidneys provide better graft survival than one

Double kidney transplantation is an accepted strategy to increase the donor pool. Regarding older donor kidneys, protocols for deciding to perform a dual or a single transplantation are mainly based on preimplantation biopsies. The aim of our study was to evaluate the long-term graft and patient survivals of our "Dual Kidney Transplant program." Patients who lost one of their grafts peritransplantation were used as controls. A total of 203 patients underwent kidney transplantation from December 1996 to January 2008 in our "old for old" renal transplantation program. We excluded 21 patients because of a nonfunctioning kidney, hyperacute rejection, or patient death with a functioning graft within the first month. Seventy-nine among 182 kidney transplantation the "old for old" program were dual kidney transplantation (DKT). Fifteen of 79 patients lost one of their kidney grafts (the uninephrectomized (UNX) UNX group). At 1 year, renal function was lower and proteinuria greater among the UNX than the DKT group. Patient survival was similar in both groups. However, death-censored graft survival was lower in UNX than DKT patients. The 5-year graft survival rate was 70% in UNX versus 93% in DKT cohorts (P = .04). In conclusion, taking into account the kidney shortage, our results may question whether the excellent transplant outcomes with DKT counter balance the reduced donor pool obviating acceptable transplant outcomes for more patients with single kidney transplantation.

Donor age-specific injury and immune responses

Utilization rates of organs from elderly donors have shown the highest proportional increase during the last decade. Clinical reports support the concept of transplanting older organs. However, the engraftment of such organs has been linked to accelerated immune responses based on ageing changes per se and a proinflammatory environment subsequent to compromised injury and repair mechanism. We analyzed the clinical consequences of transplanting older donor organs and present mechanistic aspects correlating age, injury repair and effects on host immunoresponsiveness.

Impact of cold ischemia time on graft survival among ECD transplant recipients: a paired kidney analysis

Delays in expanded criteria donor (ECD) kidney placement increases cold ischemia times (CIT) potentially leading to discard. The effect of increased CIT on ECD kidney transplant outcomes is unknown. We evaluated paired ECD kidneys (derived from the same donor transplanted to different recipients) from the SRTR registry transplanted between 1995 and 2009 (n = 17,514). To test the effect of CIT, we excluded paired transplants with the same CIT (n = 3286). Of 14,230 recipients (7115 donors) the median difference in CIT was 5 h (Q1 = 3 h, Q3 = 9 h). Delayed graft function (DGF) was significantly more likely between pairs with greater CIT (35% vs. 31%, p < 0.001) including substantially higher rates for CIT differences ≥ 15 h (42%). Overall graft loss was not significantly different between recipients with higher CIT relative to paired donor recipients with lower CIT (p = 0.47) or for pairs with differences of 1-3 h (p = 0.90), 4-9 h (p = 0.41), 10-14 h (p = 0.36) or ≥ 15 h (p = 0.10). Results were consistent in multivariable models adjusted for recipient factors. Although increasing cold ischemia time is a risk factor for DGF among ECD kidney transplants, there is no effect on graft survival which may suggest an important utility for donor kidneys that may not currently be considered viable.

Renovascular resistance of machine-perfused DCD kidneys is associated with primary nonfunction

Donation after cardiac death (DCD) has shown to be a valuable extension of the donor pool despite a higher percentage of primary nonfunction (PNF). Limiting the incidence of PNF is of vital importance. Renovascular resistance is believed to predict graft outcome; however the literature is inconsistent. Therefore, we studied whether renovascular resistance is associated with PNF and whether this parameter should be used to discard donor kidneys. All transplanted DCD kidneys preserved by machine perfusion at our center between 1993 and 2007 were analyzed (n = 440). The effects of renovascular resistance on PNF, delayed graft function (DGF), and graft and patient survival were examined using multivariable analyses; predictive quality by calculating the area under the curve (AUC). We showed that renovascular resistance at the start of machine perfusion was significantly and independently associated with PNF (OR 2.040, 95% CI 1.362-3.056; p = 0.001), and DGF (OR 2.345, 95% CI 1.110-4.955; p = 0.025). Predictive quality was moderate (0.609, 95% CI 0.538-0.681). Graft and patient survival were not associated with renovascular resistance. We conclude that renovascular resistance in DCD kidneys is an independent risk factor for PNF; however, the predictive value is relatively low.

Pulsatile perfusion preservation for expanded-criteria donors kidneys: Impact on delayed graft function rate

PURPOSE

Expanded criteria donors (ECD) kidneys are a potential solution to organ shortage, but exhibit more delayed graft function (DGF). We conducted a prospective controlled study aiming to evaluate the impact of pulsatile perfusion preservation (PPP) on DGF rate.

METHODS

Inclusion criteria were: 1) ECD definition (any brain-dead donor aged > 60 years or aged 50-60 years with at least 2 of the following: history of hypertension, terminal serum creatinin level = 1.5 mg/dL, death resulting from a cerebrovascular accident; 2) Donor prolonged circulatory arrest (> 20 mn); 3) previsible cold ischemia time longer than 24 hours. In each pair of kidneys, one organ was preserved with PPP and the other organ was preserved in static cold storage.

RESULTS

From February 2007 to September 2009, a total of 22 donors (44 recipients) were included. Recipients were comparable in the two groups with respect to demographic and immunological data. The rate of DGF was significantly lower (9% vs. 31.8%, p = 0.021) in the PPP group. At 1, 3, and 12 months, renal function was comparable in the two groups.

CONCLUSIONS

Pulsatile perfusion preservation significantly reduced DGF rate in ECD kidney transplantation.

Illinois statewide dual kidney transplantation experience--are we appropriately selecting kidneys?

PURPOSE

Dual kidney transplantation is a technique that some transplant centers have adopted to increase organ use. We investigated whether kidneys that were recovered and discarded were similar to those kidneys used for dual kidney transplantation.

MATERIALS AND METHODS

We reviewed all kidneys recovered, biopsied and placed on machine perfusion in the state of Illinois from January 2002 to October 2009. We selected those kidneys used in dual kidney transplant, and compared their characteristics to those of kidneys that were recovered and biopsied but ultimately discarded. The immediate and 1-year outcomes of the dual kidney transplant recipients were analyzed.

RESULTS

During the study period 60 dual transplants were performed while 94 kidney pairs were discarded. Overall donors from the used group had a lower mean creatinine clearance, older mean patient age, lower percentage of glomerulosclerosis, higher final flow rate and lower resistance. However, the comparison between those kidneys used successfully with 1-year graft survival and those discarded demonstrated only 3 less favorable parameters among the discarded group, namely a higher percentage of glomerulosclerosis (18.5% vs 13.9%, p=0.024), a higher degree of interstitial fibrosis and a higher final resistance (0.39 vs 0.31, p<0.001).

CONCLUSIONS

The considerable overlap in demographics, histology and perfusion parameters between used and discarded kidneys suggests that many kidneys that were recovered and discarded could have been used in dual kidney transplantation with acceptable outcomes. This highlights the need for further study of how kidneys are selected and used.

Graft quality assessment in kidney transplantation: not an exact science yet!

PURPOSE OF REVIEW

The enduring donor shortage necessitates the development of tools capable of objectively assessing kidney graft quality and thereby allowing the safer and wider use of expanded criteria donors and kidneys donated after cardiac death. We summarize current assessment tools available prior to procurement and during preservation.

RECENT FINDINGS

Several donor risk scores, combining donor and recipient risk factors of inferior graft outcome, exist but all lack predictive power. Histological scoring of glomerulosclerosis, tubular atrophy, interstitial fibrosis, and vascular damage in pretransplantation kidney biopsies can supply reliable, reproducible data on the actual kidney state but prospective data on their use in graft assessment are lacking. Renal resistance and certain perfusate biomarker concentrations during machine perfusion are independent risk factors of delayed graft function, but neither method has sufficient predictive power to allow kidney discard.

SUMMARY

Available tools for graft quality assessment have their intrinsic value but none offer the necessary power to predict graft outcome for a specific donor-recipient pair. This is probably due to the multitude of donor, preservation, and recipient factors at stake. Only combining these factors might improve prediction of graft outcome and allow safer use of expanded criteria donors and kidneys donated after cardiac death.

Lessons learned from a single center's experience with 134 donation after cardiac death donor kidney transplants

BACKGROUND

Reports of kidney transplantation from donation after cardiac death (DCD) donors describe high rates of delayed graft function (DGF).

STUDY DESIGN

From April 1, 2003 to October 17, 2010, we performed 134 kidney transplants from DCD donors including 120 (90%) from standard-criteria donors (SCDs) and 14 (10%) from expanded-criteria donors (ECDs). Nineteen kidneys were recovered from donors managed with extracorporeal interval support for organ retrieval (EISOR) after cardiac arrest to minimize ischemic injury.

RESULTS

Comparison of donor and recipient characteristics found no differences for cases managed with or without EISOR. Overall actuarial patient survival rates were 93%, 91%, and 89% at 1, 3, and 5 years, respectively, with a mean follow-up of 31 months. Overall actuarial kidney graft survival rates were 89%, 76%, and 76% at 1, 3, and 5 years, respectively. Actuarial graft survival rates of DCD ECD kidneys were 58% and 48% at 1 and 3 years, compared with 90% and 79% at 1 and 3 years for non-ECD grafts (p = 0.013). DGF occurred in 73 patients (54%) overall and was reduced from 55% to 21% (p = 0.016) with the use of EISOR in locally recovered kidneys. The mean resistance value on machine perfusion and the mean estimated glomerular filtration rate 1 month after transplantation were both improved (p < 0.05) in kidneys from donors managed with EISOR. Mean initial hospital stay was reduced from 8.0 to 5.0 days in patients receiving kidneys recovered with EISOR (p = 0.04).

CONCLUSIONS

EISOR is associated with a lower rate of DGF, lower graft resistance on machine perfusion, and shorter initial hospitalization. Kidneys from DCD SCDs have excellent medium-term outcomes and represent an important means of expanding the donor pool. Kidneys from DCD ECDs have inferior outcomes.

Significance of preimplantation analysis of kidney biopsies from expanded criteria donors in long-term outcome

BACKGROUND

The shortage of organs has led to expanding the criteria for donors. Histologic evaluations before transplantation may enable the identification of organs unsuitable for single implantation. The aim of this study was to evaluate the histologic findings as prognostic factors of allograft survival from expanded criteria donors (ECDs).

METHODS

We included a cohort of 136 single transplantations with kidneys from ECD and correlated the preimplantation pathologic findings with graft failure. Renal structures from ECD older (n=104) or younger (n=32) than 60 years were evaluated histologically for renal senescence and rated with a total histologic score. A multivariate Cox analysis was performed to identify predictors of graft failure.

RESULTS

Glomerulosclerosis was the most prevalent lesion in biopsies from donors older and younger than 60 years (P=0.002); interstitial fibrosis was more severe in biopsies from older donors (P=0.001); older donors showed a higher prevalence of tubular atrophy (P=0.022), and vascular compartment showed no significant differences. Kidney biopsy-based scoring system ranged from 0 to 15 points, indicating the presence of changes in the renal parenchyma. Biopsies with total histologic scores less than or equal to 5 showed significantly better 5-year graft survival than those with scores more than 5 (P<0.001). A preimplantation score more than 5 points remained an independent predictor of graft failure (hazard ratio 6.95; 95% confidence interval 1.57-30).

CONCLUSIONS

Histologic analysis of kidney biopsies before transplantation is a valuable tool for facilitating the selection of viable grafts from ECD donors. When the total score is more than 5, single kidney transplantation from ECD should not be recommended for patients similar to this study population.

Consequences of transplant quality on chronic allograft nephropathy

Using kidneys from expanded-criteria donors to alleviate organ shortage has raised concern on reduced transplant outcomes. In this paper, we review how critical donor-related factors such as donor age, brain death, and consequences of ischemia-reperfusion injury (IRI) determine graft quality and impact chronic allograft nephropathy. We propose that combinatorial effects of organ-intrinsic features associated with increasing age and unspecific injuries related to brain death and IRI will impact innate and adaptive immune responses. Future research will need to explore avenues to optimize donor management, organ preservation, adapted immunosuppressive strategies, as well as modifications of the allocation of suboptimal allografts.

Assessment of kidney organ quality and prediction of outcome at time of transplantation

The critical importance of donor organ quality, i.e., number of surviving nephrons, ability to withstand injury, and capacity for repair in determining short- and long-term outcomes is becoming increasingly clear. This review provides an overview of studies to assess donor kidney quality and subsequent transplant outcomes based on clinical pathology and transcriptome-based variables available at time of transplantation. Prediction scores using clinical variables function when applied to large data sets but perform poorly for the individual patient. Histopathology findings in pre-implantation or post-reperfusion biopsies help to assess structural integrity of the donor kidney, provide information on pre-existing donor disease, and can serve as a baseline for tracking changes over time. However, more validated approaches of analysis and prospective studies are needed to reduce the number of discarded organs, improve allocation, and allow prediction of outcomes. Molecular profiling detects changes not seen by morphology or captured by clinical markers. In particular, molecular profiles provide a quantitative measurement of inflammatory burden or immune activation and reflect coordinated changes in pathways associated with injury and repair. However, description of transcriptome patterns is not an end in itself. The identification of predictive gene sets and the application to an individualized patient management needs the integration of clinical and pathology-based variables, as well as more objective reference markers of transplant function, post-transplant events, and long-term outcomes.

Analysis of four scoring systems and monocentric experience to optimize criteria for marginal kidney transplantation

There is a strong need among the transplantation community to identify common criteria to utilize the pool of expanded criteria donors (ECD), considering the disparity between organ demand and supply as well as the benefits of transplantation on long-term mortality compared with survival on dialysis, also in patients transplanted with these organs. The purpose of this article was to analyze scoring systems proposed in literature by Nyberg, Anglicheau, Rao (Kidney Donor Risk Index), and Schold, seeking to verify whether our clinical and histological allocation strategy matched the Nyberg score. Herein we have reported the results of a preliminary retrospective study on the 5-year outcomes of organs from 60 marginal donors, who were older than 50 years and histologically evaluated before implantation. The donors matched Nyberg class C and D, that is, marginal donors. We noted a tendency toward an association between global and vascular scores with class D (odds ratio 2.2 and 4.3, respectively). Kaplan-Meier graft survival curves were similar to Nyberg data: 83% for class C versus 73% for class D at 5 years. Without any comparison to the Nyberg score, the only feature that was predictive of renal function at 5 years in our population was hypertension in the donor. Further studies are required to identify which of the scoring systems--clinical and/or histological--is more suitable to allocate ECD kidneys and to predict recipient outcomes.

Increasing organ donation and transplantation: the U.S. experience over the past decade

The growing gap between the need for and supply of transplantable organs in the U.S. led to several initiatives over the past decade. UNOS implemented policies intended to facilitate the use of expanded criteria donor kidneys with mixed success. The U.S. government sponsored several organ donation and transplantation collaboratives, leading to significant increases in organ donation over several years. The use of organs from donors dying from cardiac death has increased steadily over the past decade, with such donors now exceeding 10% of the total. Revisions of state anatomic death acts allowed persons to declare their intention to donate by enrolling in state donor registries, facilitating the identification of willing donors by organ procurement organization. Despite these initiatives, the disparity between organ demand and supply has continued to grow, primarily as a result of marked increase in the number of candidates awaiting kidney transplantation.

Import kidney transplants from nonmandatory share deceased donors: characteristics, distribution and outcomes

Outcomes of locally rejected kidneys transplanted at other centers (import KTX) are unknown. SRTR data from 2000 to 2009 of deceased-donor KTXs excluding 0-mismatch, paybacks, and other mandatory shares were compared by location of KTX at local (n = 48,165), regional (n = 4428) or national (n = 4104) centers using multivariable regression models. Compared to nonmandatory share local transplants, import KTX were associated with significantly higher overall risks of patient death (regional aHR 1.15, p < 0.01; national aHR 1.14, p < 0.01), and graft failure (regional aHR 1.17, p < 0.01; national aHR1.21, p < 0.01). In paired analysis, the risk of delayed graft function (DGF) for import KTX was higher compared to locally transplanted mates (regional aOR 1.53, p < 0.01, national aOR 2.14, p < 0.01); however, despite longer ischemia times, overall graft survival was similar. Mean cold ischemia times (CIT) pre- and post-DonorNet were similar for local and regional transplants, but significantly higher for national transplants (28.9 ± 9.9 vs. 29.9 ± 9.7 h, respectively, p = 0.01). Import KTX is associated with increased risks of graft failure, patient death and DGF. In the era of DonorNet cold ischemia times of kidneys imported to regional centers are not improved compared to pre-DonorNet; and, those of national centers are significantly prolonged.

Favorable outcomes with machine perfusion and longer pump times in kidney transplantation: a single-center, observational study

BACKGROUND

Hypothermic machine perfusion (MP) preservation is used for all deceased donor kidney transplants at our center. Kidneys are placed in cold storage at retrieval, then transferred to MP on arrival. Because a lack of consensus regarding optimal use of MP still exists, we evaluated the overall impact of using MP at our center and the prognostic value of MP (Pump) time.

METHODS

We retrospectively analyzed 339 adult, primary deceased donor kidney transplant recipients who were pooled across three prospective, randomized immunosuppression trials (since 2000) at our center. In addition to providing overall results for delayed graft function (DGF) (requirement for dialysis in the first week), slow graft function (SGF), first biopsy-proven acute rejection (BPAR), and graft failure, stepwise logistic and Cox regression analyses were used to determine the prognostic value of pump time, particularly after controlling for other significant prognosticators.

RESULTS

Mean cold storage and pump times were 6.6 and 26.7 hr, consistent across immunosuppression protocols. Overall DGF and SGF rates were 4.4% (15/339) and 12.1% (41/339). DGF was equally low for pump time less than 24 vs. more than or equal to 24 hr, 5.2% (6/116) vs. 4.0% (9/223) (P=0.63), with similar results after adjusting for known DGF predictors. A significantly lower first BPAR rate was observed for longer pump time (as a continuous variable) among more immunologically active recipients (those having more risk factors: DGF, age <50 yr, and non-white) (univariable P=0.005; multivariable P=0.009), with an estimated hazard ratio of 0.43 (P=0.006) favoring pump time more than or equal to 24 hr among those with more than or equal to two risk factors. CONCLUSIONS.: In this single-center, observational study, MP with prolonged pump times was associated with low DGF/SGF and first BPAR rates, supporting continued use of MP.

Current state of hypothermic machine perfusion preservation of organs: The clinical perspective

This review focuses on the application of hypothermic perfusion technology as a topic of current interest with the potential to have a salutary impact on the mounting clinical challenges to improve the quantity and quality of donor organs and the outcome of transplantation. The ex vivo perfusion of donor organs on a machine prior to transplant, as opposed to static cold storage on ice, is not a new idea but is being re-visited because of the prospects of making available more and better organs for transplantation. The rationale for pursuing perfusion technology will be discussed in relation to emerging data on clinical outcomes and economic benefits for kidney transplantation. Reference will also be made to on-going research using other organs with special emphasis on the pancreas for both segmental pancreas and isolated islet transplantation. Anticipated and emerging benefits of hypothermic machine perfusion of organs are: (i) maintaining the patency of the vascular bed, (ii) providing nutrients and low demand oxygen to support reduced energy demands, (iii) removal of metabolic by-products and toxins, (iv) provision of access for administration of cytoprotective agents and/or immunomodulatory drugs, (v) increase of available assays for organ viability assessment and tissue matching, (vi) facilitation of a change from emergency to elective scheduled surgery with reduced costs and improved outcomes, (vii) improved clinical outcomes as demonstrated by reduced PNF and DGF parameters, (viii) improved stabilization or rescue of ECD kidneys or organs from NHBD that increase the size of the donor pool, (ix) significant economic benefit for the transplant centers and reduced health care costs, and (x) provision of a technology for ex vivo use of non-transplanted human organs for pharmaceutical development research.

Improving distribution efficiency of hard-to-place deceased donor kidneys: Predicting probability of discard or delay

We recently showed that DonorNet 2007 has reduced the efficiency of kidney distribution in the United States, particularly for those with prolonged cold ischemia time (CIT), by requiring systematic allocation of all kidneys regardless of quality. Reliable early identification of those most likely to be discarded or significantly delayed would enable assigning them to alternate, more efficient distribution strategies. Based on 39 035 adult kidneys recovered for possible transplantation between 2005 and 2008, we created a regression model that reliably (AUC 0.83) quantified the probability that a given kidney was either discarded or delayed beyond 36 h of CIT (Probability of Discard/Delay, PODD). We then analyzed two PODD cutoffs: a permissive cutoff that successfully flagged over half of those kidneys that were discarded/delayed, while only flagging 7% of kidneys that were not eventually discarded/delayed, and a more stringent cutoff that erroneously flagged only 3% but also correctly identified only 34%. Kidney transplants with high PODD were clustered in a minority of centers. Modifications of the kidney distribution system to more efficiently direct organs with high PODD to the centers that actually use them may result in reduced CIT and fewer discards.

Listing for expanded criteria donor kidneys in older adults and those with predicted benefit

Certain patient groups are predicted to derive significant survival benefit from transplantation with expanded criteria donor (ECD) kidneys. An algorithm published in 2005 by Merion and colleagues characterizes this group: older adults, diabetics and registrants at centers with long waiting times. Our goal was to evaluate ECD listing practice patterns in the United States in terms of these characteristics. We reviewed 142 907 first-time deceased donor kidney registrants reported to United Network for Organ Sharing (UNOS) between 2003 and 2008. Of registrants predicted to benefit from ECD transplantation according to the Merion algorithm ('ECD-benefit'), 49.8% were listed for ECD offers ('ECD-willing'), with proportions ranging from 0% to 100% by transplant center. In contrast, 67.6% of adults over the age of 65 years were ECD-willing, also ranging from 0% to 100% by center. In multivariate models, neither diabetes nor center waiting time was significantly associated with ECD-willingness in any subgroup. From the time of initial registration, irrespective of eventual transplantation, ECD-willingness was associated with a significant adjusted survival advantage in the ECD-benefit group (HR for death 0.88, p < 0.001) and in older adults (HR 0.89, p < 0.001), but an increased mortality in non-ECD-benefit registrants (HR 1.11, p < 0.001). In conclusion, ECD listing practices are widely varied and not consistent with published recommendations, a pattern that may disenfranchise certain transplant registrants.

Islet isolation for clinical transplantation

Islet transplantation is emerging as a viable treatment option for selected patients with type 1 diabetes. Following the initial report in 2000 from Edmonton of insulin independence in seven out of seven consecutive recipients, there has been a huge expansion in clinical islet transplantation. The challenge we now face is the apparent decline in graft function over time. Isolating high-quality human islets which survive and function for a longer period will no doubt contribute to further improvement in long-term clinical outcome. This chapter reviews the selection of appropriate donors for islet isolation and transplantation, describes each step during islet isolation, and discusses the scope for further improvements.

Pulsatile perfusion of kidney allografts

PURPOSE OF REVIEW

The purpose of this article is to describe the current use of pulsatile kidney perfusion during organ preservation and the effects on kidney allograft outcomes and utilization.

RECENT FINDINGS

As of spring 2008, there were 75 629 candidates on the kidney waiting list in the USA according to United Network for Organ Sharing data. In 2006, a total of 1815 deceased donor expanded criteria donors kidneys were transplanted, and approximately 80% of those kidneys had cold ischemic time of over 12 h. The utilization of kidney pulsatile perfusion varies extensively throughout the USA with rates of 7-12% in our institution.

SUMMARY

Data on the use of pulsatile hypothermic perfusion for kidneys during organ preservation are limited and mostly retrospective. Most authors agree that pulsatile perfusion is safe and leads to a decrease in delayed graft function, especially for marginal kidneys from extended criteria or deceased donors. The long-term effects of delayed graft function on graft survival remain to be seen. With the recent large-sampled international prospective randomized trial recently completed, we may see more kidneys pulsatile perfused. This may lead to an increase in the utilization of otherwise discarded kidneys, though these data are difficult to extrapolate.

Renal transplantation with expanded criteria donors: the experience of one Portuguese center

BACKGROUND

The shortage of kidneys available for transplantation has led to enlarged criteria donors (ECD): namely, donors older than 60 years or aged between 50 and 59 years with 2 of the following characteristics-hypertension, predonation serum creatinine level higher than 1.5 mg/dL or cerebrovascular disease as the cause of death. The aim of this study was to analyze renal transplants using ECD compared with standard criteria donors (SCD) concerning the incidences of delayed graft function (DGF), acute rejection episodes (ARE), and patient and graft survivals.

MATERIALS AND METHODS

This retrospective study of 409 cadaveric renal transplants over the last 4 years identified ECD in contrast with SCD.

RESULTS

Of the transplants, 24.4% used ECD. The baseline characteristics of recipients of ECD versus SCD kidneys were similar, except for age and cold ischemia time. Comparing ECD and SCD, we observed an higher incidence of DGF (35% vs 18%), occurrence of ARE (34.4% vs 16.6%), average serum creatinine levels at 6 (1.87 vs 1.4 mg/dL), and 12 months (1.88 vs 1.43 mg/dL) as well as lower graft survival at 1 (82% vs 91%) and 3 years (75% vs 84%) after transplantation. Recipient survival at 1 year was not different. Multivariate analysis identified recipient age, cold ischemia time, ARE, and DGF as risk factors for graft failure.

CONCLUSIONS

Renal transplantation with grafts from ECD shows significantly worse outcomes with higher rates of DGF and ARE, worse graft function, and lower graft survival.

Organ donation and utilization in the United States: 1998-2007

Organ transplantation remains the only life-saving therapy for many patients with organ failure. Despite the work of the Organ Donation and Transplant Collaboratives, and the marked increases in deceased donors early in the effort, deceased donors only rose by 67 from 2006 and the number of living donors declined during the same time period. There continue to be increases in the use of organs from donors after cardiac death (DCD) and expanded criteria donors (ECD). This year has seen a major change in the way organs are offered with increased patient safety measures in those organ offers made by OPOs using DonorNet. Unfortunately, the goals of 75% conversion rates, 3.75 organs transplanted per donor, 10% of all donors from DCD sources and 20% growth of transplant center volume have yet to be reached across all donation service areas (DSAs) and transplant centers; however, there are DSAs that have not only met, but exceeded, these goals. Changes in organ preservation techniques took place this year, partly due to expanding organ acceptance criteria and increasing numbers of ECDs and DCDs. Finally, the national transplant environment has changed in response to increased regulatory oversight and new requirements for donation and transplant provider organizations.

Renal transplantation in the elderly

Elderly patients are increasingly being considered for kidney transplantation due to a global explosion of the aging population with end-stage renal disease (ESRD). However, mounting scarcity of available organs for transplant has led to a wider disparity between organ supply and demand. Consequently, the criteria for accepting kidneys for transplantation have been extended in an attempt to allow the use of organs from elderly donors or those with significant co-morbidities, so-called "expanded criteria donor" (ECD) kidneys. Excellent outcomes have been achieved from ECD kidneys with appropriate donor and recipient profiling and selection. With increasing recovery efforts directed at older donors, the concept of age-matching is becoming more accepted as a method of optimizing utilization of organs in elderly donors and recipients. Utilization of pulsatile perfusion has further improved ECD outcomes and helped the decision-making process for the UNOS (United Network for Organ Sharing) offer. However, age-related immune dysfunction and associated co-morbidities make the elderly transplant recipients ever more susceptible to complications associated with immunosuppressive agents. Consequently, the elderly population is at a higher risk to develop infections and malignancy in the post-transplant period notwithstanding improved transplant outcomes. Appropriate immunosuppressive agents and dosages should be selected to minimize adverse events while reducing the risk of acute rejections and maximizing patient and renal allograft survival.

Association of lower costs of pulsatile machine perfusion in renal transplantation from expanded criteria donors

Pulsatile machine perfusion (PMP) has been shown to reduce delayed graft function (DGF) in expanded criteria donor (ECD) kidneys. Here, we investigate whether there is a cost benefit associated with PMP utilization in ECD kidney transplants. We analyzed United States Renal Data System (USRDS) data describing Medicare-insured ECD kidney transplant recipients in 1995-2004 (N = 5840). We examined total Medicare payments for transplant hospitalization and annually for 3 years posttransplant according to PMP utilization. After adjusting for other recipient, donor and transplant factors, PMP utilization was associated with a $2130 reduction (p = 0.007) in hospitalization costs. PMP utilization was also associated with lower DGF risk (p < 0.0001). PMP utilization did not predict differences in rejection, graft survival, patient survival, or costs at 1, 2 and 3 years posttransplant. PMP utilization is correlated with lower costs for the transplant hospitalization, which is likely due to the associated reduction in DGF among recipients of PMP kidneys. However, there is no difference in long-term Medicare costs for ECD recipients by PMP utilization. A prospective trial is necessary as it will help determine if the associations seen here are due to PMP utilization and not differences in the population studied.

A simple clinico-histopathological composite scoring system is highly predictive of graft outcomes in marginal donors

The predictive value of pre-implantation biopsies versus clinical scores has not been studied extensively in marginal donors. Pre-implantation biopsies were performed in 313 kidneys from donors that were > or = 50 years of age (training set, n = 191; validation set, n = 122). The value of the donor clinical parameters and histological results in predicting 1-year estimated glomerular filtration rate (eGFR) <25 mL/min/1.73 m(2) was retrospectively evaluated. In multivariate analysis, the only clinical parameters associated with low eGFR were donor hypertension and a serum creatinine level > or =150 micromol/L before organ recovery. Clinical scores (Nyberg and Pessione) were not significantly associated with graft function. Regarding histological parameters, univariate analysis showed that glomerulosclerosis (GS) (p = 0.02), arteriolar hyalinosis (p = 0.03) and the Pirani (p = 0.02) and chronic allograft damage index (CADI) (p = 0.04) histological scores were associated with low eGFR. The highest performance in predicting low eGFR was achieved using a composite score that included donor serum creatinine (> or =150 micromol/L or <150 micromol/L), donor hypertension and GS (> or =10% or <10%). The validation set confirmed the critical importance of taking into account biopsy and clinical parameters during marginal donor evaluation. In conclusion, clinical scores are weak predictors of graft outcomes with marginal donors. Instead, a simple and convenient composite score strongly predicts graft function and survival and may facilitate optimal allocation of marginal donors.

The Maryland aggregate pathology index: a deceased donor kidney biopsy scoring system for predicting graft failure

Despite the common use of diagnostic pretransplant deceased donor kidney biopsy, there is no consensus on the prognostic significance of the pathologic findings. In order to assist clinicians with interpretation we analyzed 371 pretransplant biopsies and correlated the findings with graft failure. Glomerular pathology was assessed with percent glomerulosclerosis (GS), glomerular size and periglomerular fibrosis (PGF); vascular pathology with arterial wall-to-lumen ratio (WLR) and arteriolar hyalinosis and interstitial pathology with measurement of cumulative fibrosis and presence of scar. Using two-thirds of the study population as a model-development cohort, we found that biopsy features independently associated with an increased risk of graft failure were GS > or =15%, interlobular arterial WLR > or =0.5 and the presence of PGF, arteriolar hyalinosis or scar. The Maryland Aggregate Pathology Index (MAPI), was developed from these parameters and validated on the remaining one-third of the population. Five-year actuarial graft survival was 90% for kidneys with MAPI scores between 0 and 7, 63% for scores from 8 to 11 and 53% for scores from 12 to 15 (p < 0.001). We conclude MAPI may help transplant physicians estimate graft survival from the preimplantation biopsy findings, in clinical situations similar to this study population (cold ischemia over 24 h, GS < 25%).

A systematic review of kidney transplantation from expanded criteria donors

BACKGROUND

During the past few years, there has been renewed interest in the use of expanded criteria donors (ECD) for kidney transplantation to increase the numbers of deceased donor kidneys available. More kidney transplants would result in shorter waiting times and limit the morbidity and mortality associated with long-term dialysis therapy.

STUDY DESIGN

Systematic review of the literature.

SETTING & POPULATION

Kidney transplantation population.

SELECTION CRITERIA FOR STUDIES

Studies were identified by using a comprehensive search through MEDLINE and EMBASE databases. Inclusion criteria were case series, cohort studies, and randomized controlled trials assessing kidney transplantation in adult recipients using ECDs.

PREDICTOR

A special focus was given to studies comparing the evolution of kidney transplantation between standard criteria donors (defined as a donor who does not meet criteria for donation after cardiac death or ECD) and ECDs (defined as any brain-dead donor aged > 60 years or a donor aged > 50 years with 2 of the following conditions: history of hypertension, terminal serum creatinine level >or= 1.5 mg/dL, or death resulting from a cerebrovascular accident).

OUTCOMES

Criteria used to define and select ECDs, practice patterns, long-term outcomes, early complications, and some patient issues, such as selection criteria and immunosuppressive management.

RESULTS

ECD kidneys have worse long-term survival than standard criteria donor kidneys. The optimal ECD kidney for donation depends on adequate glomerular filtration rate and acceptable donor kidney histological characteristics, albeit the usefulness of biopsy is debated.

LIMITATIONS

This review is based mainly on data from observational studies, and varying amounts of bias could be present. We did not attempt to quantitatively analyze the effect of ECD kidneys on kidney transplantation because of the huge heterogeneity found in study designs and definitions of ECD.

CONCLUSIONS

Based on the available evidence, we conclude that patients younger than 40 years or scheduled for kidney retransplantation should not receive an ECD kidney. Patients 40 years or older, especially with diabetic nephropathy or nondiabetic disease, but a long expected waiting time for kidney transplantation, show better survival receiving an ECD kidney than remaining on dialysis therapy.