Survival benefit of accepting kidneys from older donation after cardiac death donors

Challenges and opportunities in organ donation after circulatory death

In recent years, there has been resurgence in donation after circulatory death (DCD). Despite that, the number of organs transplanted from these donors remains low due to concerns about their function and a lack of an objective assessment at the time of donation. This overview examines the current DCD practices and the classification modifications to accommodate regional perspectives. Several risk factors underscore the reluctance to accept DCD organs, and we discuss the modern strategies to mitigate them. The advent of machine perfusion technology has revolutionized the field of DCD transplantation, leading to improved outcomes and better organ usage. With many strategies at our disposal, there is an urgent need for comparative trials to determine the optimal use of perfusion technologies for each donated organ type. Additional progress in defining therapeutic strategies to repair the damage sustained during the dying process should further improve DCD organ utilization and outcomes. However, there remains wide variability in access to DCD donation and transplantation, and organizational efforts should be doubled up with consensus on key ethical issues that still surround DCD donation in the era of machine perfusion.

Impact of Cold Ischemia Time and Donor Age on Donation After Circulatory Death Kidney Transplant Outcomes: A UNOS Mate-Kidney Analysis

BACKGROUND

The association between prolonged cold ischemia times (CIT), donor age, and outcomes in kidney transplant recipients (KTRs) from donors after circulatory death (DCD) remains uncertain. We aimed to compare allograft outcomes in DCD-donor KTRs according to CIT and age.

METHODS

UNOS database study (2010-2024) of DCD-donor KTRs on tacrolimus maintenance. We developed a mate-kidney analysis, comparing outcomes where one mate kidney had CIT >24 and the other ≤24 h. We evaluated patient death, all-cause allograft failure, and death-censored graft failure (DCGF) using multivariable stratified Cox proportional hazards models. We compared outcomes across age groups (≥50 or <50 years) and 6-h-period CIT deltas between mate kidneys. We assessed delayed graft function (DGF) occurrence with multivariable conditional logistic regression.

RESULTS

We included 4092 DCD-donor mate-kidney pairs. There were no differences between CIT >24 versus ≤24 h in patient death (aHR 1.12, 95% CI 0.97-1.30), all-cause allograft failure (aHR 1.10, 95% CI 0.98-1.24), or DCGF (aHR 1.07, 95% CI 0.90-1.27). Similar results were observed when comparing outcomes by age group and 6-h-period CIT deltas between mate kidneys. Compared to shorter CITs, CITs >24 h were associated with increased DGF likelihood (aOR 1.42, 95% CI 1.25-1.60), as were increasing CIT deltas.

CONCLUSION

CITs >24 h in DCD-donor KTRs were not associated with adverse allograft outcomes, irrespective of age group. However, prolonged CITs were associated with increased DGF likelihood. Increasing the acceptance of both mate kidney from DCD donors should be considered despite projected CITs >24 h.

A Survey of United States Transplant Center Donation After Circulatory Death Kidney Transplant Practices in the Modern Era

BACKGROUND

The mismatch between the number of patients awaiting kidney transplantation and the supply of donor organs has contributed to the increase in kidney transplantation from donors after circulatory death (DCD). Persistently long waiting times have led the transplant community to continue to explore the use of expanded- criteria DCD kidneys. In parallel, advances in organ preservation strategies have contributed to an overall increase in DCD organ transplantation and are altering the transplant landscape. Some of these techniques may improve kidney allograft outcomes and affect how DCD kidneys are used. We aimed to better understand practices in accepting DCD kidney offers in the modern era.

METHODS

Directors of 196 US kidney transplant centers were emailed a link to an online survey over a 5-week period.

RESULTS

Forty-eight out of the 364 directors (13%) responded, with all United Network for Organ Sharing regions represented. Definitions of warm ischemia time (WIT) used in DCD kidney evaluation varied widely among the respondents. The maximum total WIT limit varied, with 19 (39.6%) <60-minute responses, followed by 16 (33%) <90-minute responses, and 10 (20.8%) <120-minute responses.

CONCLUSIONS

Despite increasing DCD kidney transplantation volumes in the United States, there are no standardized procurement biopsy practices, organ procurement organization preoperative protocols, or consensus definition or limits of WIT. Agreement on terminology may facilitate rapid clinical communication, efficiency of organ allocation and utilization, recording of data, research, and improvements in policy.

Sirtuin 3 in renal diseases and aging: From mechanisms to potential therapies

The longevity protein sirtuins (SIRTs) belong to a family of nicotinamide adenine dinucleotide (NAD+)-dependent deacetylases. In mammals, SIRTs comprise seven members (SIRT1-7) which are localized to different subcellular compartments. As the most prominent mitochondrial deacetylases, SIRT3 is known to be regulated by various mechanisms and participate in virtually all aspects of mitochondrial homeostasis and metabolism, exerting significant impact on multiple organs. Notably, the kidneys possess an abundance of mitochondria that provide substantial energy for filtration and reabsorption. A growing body of evidence now supports the involvement of SIRT3 in several renal diseases, including acute kidney injury, chronic kidney disease, and diabetic nephropathy; notably, these diseases are all associated with aging. In this review, we summarize the emerging role of SIRT3 in renal diseases and aging, and highlights the intricate mechanisms by which SIRT3 exerts its effects. In addition, we highlight the potential therapeutic significance of modulating SIRT3 and provide valuable insights into the therapeutic role of SIRT3 in renal diseases to facilitate clinical application.

Waitlist and Transplant Outcomes in Organ Donation After Circulatory Death: Trends in the United States

OBJECTIVES

To summarize waitlist and transplant outcomes in kidney, liver, lung, and heart transplantation using organ donation after circulatory death (DCD).

BACKGROUND

DCD has expanded the donor pool for solid organ transplantation, most recently for heart transplantation.

METHODS

The United Network for Organ Sharing registry was used to identify adult transplant candidates and recipients in the most recent allocation policy eras for kidney, liver, lung, and heart transplantation. Transplant candidates and recipients were grouped by acceptance criteria for DCD versus brain-dead donors [donation after brain death (DBD)] only and DCD versus DBD transplant, respectively. Propensity matching and competing-risks regression was used to model waitlist outcomes. Survival was modeled using propensity matching and Kaplan-Meier and Cox regression analysis.

RESULTS

DCD transplant volumes have increased significantly across all organs. Liver candidates listed for DCD organs were more likely to undergo transplantation compared with propensity-matched candidates listed for DBD only, and heart and liver transplant candidates listed for DCD were less likely to experience death or clinical deterioration requiring waitlist inactivation. Propensity-matched DCD recipients demonstrated an increased mortality risk up to 5 years after liver and kidney transplantation and up to 3 years after lung transplantation compared with DBD. There was no difference in 1-year mortality between DCD and DBD heart transplantation.

CONCLUSIONS

DCD continues to expand access to transplantation and improves waitlist outcomes for liver and heart transplant candidates. Despite an increased risk for mortality with DCD kidney, liver, and lung transplantation, survival with DCD transplant remains acceptable.

Beyond donation to organ utilization in the USA

PURPOSE OF REVIEW

The deceased donor organ pool has broadened beyond young, otherwise healthy head trauma victims. But an abundance of donated organs only benefits patients if they are accepted, expeditiously transported and actually transplanted. This review focuses on postdonation challenges and opportunities to increase the number of transplants through improved organ utilization.

RECENT FINDINGS

We build upon recently proposed changes in terminology for measuring organ utilization. Among organs recovered for transplant, the nonuse rate (NUR REC ) has risen above 25% for kidneys and pancreata. Among donors, the nonuse rate (NUR DON ) has risen to 40% for livers and exceeds 70% for thoracic organs. Programme-level variation in offer acceptance rates vastly exceeds variation in the traditional, 1-year survival benchmark. Key opportunities to boost utilization include donation after circulatory death and hepatitis C virus (HCV)+ organs; acute kidney injury and suboptimal biopsy kidneys; older and steatotic livers.

SUMMARY

Underutilization of less-than-ideal, yet transplant-worthy organs remains an obstacle to maximizing the impact of the U.S. transplant system. The increased risk of inferior posttransplant outcomes must always be weighed against the risks of remaining on the waitlist. Advanced perfusion technologies; tuning allocation systems for placement efficiency; and data-driven clinical decision support have the potential to increase utilization of medically complex organs.

Donor liquid biopsy and outcomes in kidney transplantation

Kidney transplantation is the treatment of choice for patients with kidney failure. Priority on the waiting list and optimal donor-recipient matching are guided by mathematical scores, clinical variables and macroscopic observation of the donated organ. Despite the increasing rates of successful kidney transplantation, maximizing the number of available organs while ensuring the optimum long-term performance of the transplanted kidney remains both key and challenging, and no unequivocal markers are available for clinical decision making. Moreover, the majority of studies performed thus far has focused on the risk of primary non-function and delayed graft function and subsequent survival and have mainly analysed recipients' samples. Given the increasing use of donors with expanded criteria and/or cardiac death, predicting whether grafts will provide sufficient kidney function is increasingly more challenging. Here we compile the available tools for pre-transplant kidney evaluation and summarize the latest molecular data from donors that may predict short-term (immediate or delayed graft function), medium-term (6 months) and long-term (≥12 months) kidney function. The use of liquid biopsy (urine, serum, plasma) to overcome the limitations of the pre-transplant histological evaluation is proposed. Novel molecules and approaches such as the use of urinary extracellular vesicles are also reviewed and discussed, along with directions for future research.

Deciphering transplant outcomes of expanded kidney allografts donated after controlled circulatory death in the current transplant era. A call for caution

Outcomes of kidney transplantation (KT) after controlled circulatory death (cDCD) with highly expanded criteria donors (ECD) and recipients have not been thoroughly evaluated. We analyzed in a multicenter cohort of 1161 consecutive KT, granular baseline donor and recipient factors predicting transplant outcomes, selected by bootstrapping and Cox proportional hazards, and were validated in a contemporaneous European KT cohort (n = 1585). 74.3% were DBD and 25.7% cDCD-KT. ECD-KT showed the poorest graft survival rates, irrespective of cDCD or DBD (log-rank < 0.001). Besides standard ECD classification, dialysis vintage, older age, and previous cardiovascular recipient events together with low class-II-HLA match, long cold ischemia time and combining a diabetic donor with a cDCD predicted graft loss (C-Index 0.715, 95% CI 0.675-0.755). External validation showed good prediction accuracy (C-Index 0.697, 95%CI 0.643-0.741). Recipient older age, male gender, dialysis vintage, previous cardiovascular events, and receiving a cDCD independently predicted patient death. Benefit/risk assessment of undergoing KT was compared with concurrent waitlisted candidates, and despite the fact that undergoing KT outperformed remaining waitlisted, remarkably high mortality rates were predicted if KT was undertaken under the worst risk-prediction model. Strategies to increase the donor pool, including cDCD transplants with highly expanded donor and recipient candidates, should be performed with caution.

Abdominal Organ Transplantation: Noteworthy Literature in 2020

In 2020, we identified and screened over 490 peer-reviewed publications on pancreatic transplantation, over 500 on intestinal transplantation, and over 5000 on kidney transplantation. The liver transplantation section specially focused on clinical trials and systematic reviews published in 2020 and featured selected articles. This review highlights noteworthy literature pertinent to anesthesiologists and critical care physicians caring for patients undergoing abdominal organ transplantation. We explore a wide range of topics, including COVID-19 and organ transplantation, risk factors and outcomes, pain management, artificial intelligence, robotic donor surgery, and machine perfusion.