Does prolonged cold ischemia affect outcomes in donation after cardiac death donor kidney transplants?

Kidney Retransplantation in the Elderly: Are the Benefits Worth the Risks?

INTRODUCTION

An increasing number of elderly patients are undergoing either primary kidney transplantation (PrKT) or retransplantation (ReKT).

METHODS

Single-center retrospective cohort study of all deceased donor KTs (DDKTs) performed in elderly patients (age ≥65 years).

RESULTS

From December 2004 through August 2022, we performed 668 DDKTs in elderly patients including 39 ReKTs and 629 PrKTs. Mean donor age was lower in the ReKT group (44 ± 17 ReKT vs. 54 ± 13 years PrKT), as was KDPI (58 ± 24 vs. 74 ± 21% PrKT, both p < 0.05). A total of 44% of ReKT patients had a cPRA level above 50% compared to 10.3% PrKT (p < 0.0001). Rates were comparable between groups for primary nonfunction (2.6% ReKT vs. 3.7% PrKT) and delayed graft function (23% ReKT vs. 32% PrKT, p = 0.29). Five-year patient (55.2% ReKT vs. 74.3% PrKT, p = 0.03) and graft survival rates (GSRs, 55.2% ReKT vs. 64.7% PrKT, p = 0.32) were higher in the PrKT group. Death with functioning graft (DWFG) occurred in 59% of ReKT versus 37.4% of PrKT patients (p = 0.01) and accounted for 79.3% ReKT and 65.3% PrKT graft losses. Death-censored GSRs were not different (62.5% ReKT vs. 68.3% PrKT, p = 0.6).

CONCLUSIONS

Elderly recipients of deceased donor ReKTs have a higher risk of DWFG, but death-censored outcomes are comparable to age-matched PrKT recipients.

Cold Ischemia Time and Delayed Graft Function in Kidney Transplantation: A Paired Kidney Analysis

BACKGROUND

We aimed to understand the association between cold ischemia time (CIT) and delayed graft function (DGF) after kidney transplantation and the impact of organ pumping on that association.

METHODS

Retrospective cohort study using US registry data. We identified kidney pairs from the same donor where both kidneys were transplanted but had a CIT difference >0 and ≤20 h. We determined the frequency of concordant (both kidneys with/without DGF) or discordant (only 1 kidney DGF) DGF outcomes. Among discordant pairs, we computed unadjusted and adjusted relative risk of DGF associated with longer-CIT status, when then repeated this analysis restricted to pairs where only the longer-CIT kidney was pumped.

RESULTS

Among 25 831 kidney pairs included, 71% had concordant DGF outcomes, 16% had only the longer-CIT kidney with DGF, and 13% had only the shorter-CIT kidney with DGF. Among discordant pairs, longer-CIT status was associated with a higher risk of DGF in unadjusted and adjusted models. Among pairs where only the longer-CIT kidney was pumped, longer-CIT kidneys that were pumped had a lower risk of DGF than their contralateral shorter-CIT kidneys that were not pumped regardless of the size of the CIT difference.

CONCLUSIONS

Most kidney pairs have concordant DGF outcomes regardless of CIT difference, but even small increases in CIT raise the risk of DGF. Organ pumping may mitigate and even overcome the adverse consequences of prolonged CIT on the risk of DGF, but prospective studies are needed to better understand this relationship.

The Kidney Not Taken: Single-Kidney Use in Deceased Donors

BACKGROUND

The nonuse rate for kidneys recovered from deceased donors is increasing, rising to 27% in 2023. In 10% of these cases, 1 kidney is transplanted but the mate kidney is not.

STUDY DESIGN

We conducted a retrospective, single-center cohort study from December 2001 to May 2023 comparing single kidneys transplanted at our center (where the contralateral kidney was not used) to kidneys where both were transplanted separately, at least 1 of which was at our center.

RESULTS

We performed 395 single deceased-donor kidney transplants in which the mate kidney was not transplanted. Primary reasons for mate kidney nonuse were as follows: no recipient located or list exhausted (33.4%), kidney trauma or injury or anatomic abnormalities (18.7%), biopsy findings (16.7%), and poor renal function (13.7%). Mean donor and recipient ages were 51.5 ± 14.2 and 60 ± 12.6 years, respectively. Mean kidney donor profile index was 73% ± 22%, and 104 donors (26.3%) had kidney donor profile index >85%. Mean cold ischemia was 25.6 ± 7.4 hours, and 280 kidneys (70.7%) were imported. Compared with 2,303 concurrent control transplants performed at our center, primary nonfunction or thrombosis (5.1% single vs 2.8% control) and delayed graft function (35.4% single vs 30.1% control) were greater with single-kidney use (both p < 0.05). Median patient and death-censored graft survival were shorter in the single group (11.6 vs 13.5 years, p = 0.03 and 11.6 vs 19 years, p = 0.003), although the former was at least double median survival on the waiting list. In patients with functioning grafts in the single-kidney group, 1-year mean serum creatinine was 1.77 ± 0.8 mg/dL and estimated glomerular filtration rate was 44.8 ± 20 mL/min/1.73 m 2 .

CONCLUSIONS

These findings suggest that many mate kidneys are being inappropriately rejected, given the acceptable outcomes that can be achieved by transplanting the single kidney in appropriately selected recipients.

Mitochondria Transplantation Mitigates Damage in an In Vitro Model of Renal Tubular Injury and in an Ex Vivo Model of DCD Renal Transplantation

OBJECTIVES

To test whether mitochondrial transplantation (MITO) mitigates damage in 2 models of acute kidney injury (AKI).

BACKGROUND

MITO is a process where exogenous isolated mitochondria are taken up by cells. As virtually any morbid clinical condition is characterized by mitochondrial distress, MITO may find a role as a treatment modality in numerous clinical scenarios including AKI.

METHODS

For the in vitro experiments, human proximal tubular cells were damaged and then treated with mitochondria or placebo. For the ex vivo experiments, we developed a non-survival ex vivo porcine model mimicking the donation after cardiac death renal transplantation scenario. One kidney was treated with mitochondria, although the mate organ received placebo, before being perfused at room temperature for 24 hours. Perfusate samples were collected at different time points and analyzed with Raman spectroscopy. Biopsies taken at baseline and 24 hours were analyzed with standard pathology, immunohistochemistry, and RNA sequencing analysis.

RESULTS

In vitro, cells treated with MITO showed higher proliferative capacity and adenosine 5'-triphosphate production, preservation of physiological polarization of the organelles and lower toxicity and reactive oxygen species production. Ex vivo, kidneys treated with MITO shed fewer molecular species, indicating stability. In these kidneys, pathology showed less damage whereas RNAseq analysis showed modulation of genes and pathways most consistent with mitochondrial biogenesis and energy metabolism and downregulation of genes involved in neutrophil recruitment, including IL1A, CXCL8, and PIK3R1.

CONCLUSIONS

MITO mitigates AKI both in vitro and ex vivo.

Single center experience and literature review of kidney transplantation from non-ideal donors with acute kidney injury: Risk and reward

INTRODUCTION

There is limited experience transplanting kidneys from either expanded criteria donors (ECD) or donation after circulatory death (DCD) deceased donors with terminal acute kidney injury (AKI).

METHODS

AKI kidneys were defined by a donor terminal serum creatinine level >2.0 mg/dL whereas non-ideal deceased donor (NIDD) kidneys were defined as AKI/DCD or AKI/ECDs.

RESULTS

From February 2007 to March 2023, we transplanted 266 single AKI donor kidneys including 29 from ECDs, 29 from DCDs (n = 58 NIDDs), and 208 from brain-dead standard criteria donors (SCDs). Mean donor age (43.7 NIDD vs. 33.5 years SCD), KDPI (66% NIDD vs. 45% SCD), and recipient age (57 NIDD vs. 51 years SCD) were higher in the NIDD group (all p < .01). Mean waiting times (17.8 NIDD vs. 24.2 months SCD) and dialysis duration (34 NIDD vs. 47 months SCD) were shorter in the NIDD group (p < .05). Delayed graft function (DGF, 48%) and 1-year graft survival (92.7% NIDD vs. 95.9% SCD) was similar in both groups. Five-year patient and kidney graft survival rates were 82.1% versus 89.9% and 82.1% versus 75.2% (both p = NS) in the NIDD versus SCD groups, respectively.

CONCLUSIONS

The use of kidneys from AKI donors can be safely liberalized to include selected ECD and DCD donors.