Machine perfusion of kidney allografts affects early but not late graft function

Can We Predict Kidney Graft Function and Graft Survival Using Hypothermic Machine Perfusion Parameters From Donors After Circulatory Death?

Background

Hypothermic machine perfusion (HMP) reduces renal injury in donation after circulatory death donors with a high Kidney Donor Profile Index (KDPI). This study aims to characterize the correlation between KDPI, HMP parameters, and donor vitals during the withdrawal period in predicting short- and long-term graft outcomes.

Methods

ANOVA with Tukey's honestly significant difference tests compared the relationship between average flow, average resistance, peak resistance, flow slope, and resistance slope on day 30, 1-y, and 3-y eGFR, and days of delayed graft function. Graft and recipient survival rates were assessed using Kaplan-Meier analysis.

Results

The data for 72 grafts were suitable for analysis. Kidneys with KDPI >50% had a significantly higher day 30, and 1-y posttransplant eGFR, if HMP average flow was >150 mL/min, or the average resistance was <0.15 mm Hg/mL/min, compared with kidneys with also KDPI >50% but had not achieved the same pump parameters. There were no significant differences in the Kaplan-Meier analysis, considering recipient or graft survival, regardless of the KPDI score with 3- or 5-y outcomes.

Conclusions

Use of average resistance and average flow from a HMP, in conjunction with KDPI, may be predictive of the short- and long-term function of donation after circulatory death kidney transplants.

Effect of the opioid crisis on the liver transplantation donor pool: A national analysis

BACKGROUND

Over the last decade there has been a surge in overdose deaths due to the opioid crisis. We sought to characterize the temporal change in overdose donor (OD) use in liver transplantation (LT), as well as associated post-LT outcomes, relative to the COVID-19 era.

METHODS

LT candidates and donors listed between January 2016 and September 2022 were identified from the Scientific Registry of Transplant Recipients database. Trends in LT donors and changes related to OD were assessed pre- versus post-COVID-19 (February 2020).

RESULTS

Between 2016 and 2022, most counties in the United States experienced an increase in overdose-related deaths (n = 1284, 92.3%) with many counties (n = 458, 32.9%) having more than a doubling in drug overdose deaths. Concurrently, there was an 11.2% increase in overall donors, including a 41.7% increase in the number of donors who died from drug overdose. In pre-COVID-19 overdose was the 4th top mechanism of donor death, while in the post-COVID-19 era, overdose was the 2nd most common cause of donor death. OD was younger (OD: 35 yrs, IQR 29-43 vs. non-OD: 43 yrs, IQR 31-56), had lower body mass index (≥35 kg/cm2, OD: 31.2% vs. non-OD: 33.5%), and was more likely to be HCV+ (OD: 28.9% vs. non-OD: 5.4%) with lower total bilirubin (≥1.1 mg/dL, OD: 12.9% vs. non-OD: 20.1%) (all p < .001). Receipt of an OD was not associated with worse graft survival (HR .94, 95% CI .88-1.01, p = .09).

CONCLUSIONS

Opioid deaths markedly increased following the COVID-19 pandemic, substantially altering the LT donor pool in the United States.

Outcomes After Deceased Donor Kidney Transplantation Using Kidney Allografts With Marginal Perfusion Parameters

BACKGROUND

This study examines outcomes of deceased donor kidney transplantation (DDKT) in recipients of kidney allografts with marginal perfusion parameters.

METHODS

Allografts with marginal perfusion parameters (resistance index [RI] >0.4 and pump flow rate [F] <70 mL/min; MP group) were compared with those with good parameters (RI <0.4 and F >70 mL/min; GP group) for DDKT recipients between January 1996 and November 2017 after hypothermic pulsatile perfusion. Demographics, creatinine, cold ischemia times (CIT), delayed graft function (DGF), and recipient glomerular filtration rate at pre- and post-transplant were noted. The primary outcome was graft survival post-transplant.

RESULTS

In the MP (n = 31) versus GP (n = 1281) group, the median recipient was aged 57 years versus 51 years; the median donor was aged 47 versus 37 years; terminal creatinine was 0.9 versus 0.9 mg/dL; CIT was 10.2 versus 13 hours, and the RI and flow were 0.46 and 60 mL/min versus 0.21 and 120 mL/min. The DGF rate was 19% (MP) versus 8% (GP). The graft survival in the MP versus GP group was 81% versus 90% (1 year), 65% versus 79% (3 years), 65% versus 73% (4 years), and 45% versus 68% (5 years).

CONCLUSION

Carefully selected kidney allografts after comprehensive donor and recipient evaluation may allow for the use of these routinely discarded kidneys with marginal perfusion parameters.

Impact of T Lymphocytes Isolated from Liver Perfusate of Deceased Brain Donors on Kidney Transplantation: Preliminary Evidence and Future Directions

BACKGROUND

Ischemia/reperfusion injury (IRI), acute rejection (AR), and delayed graft function (DGF) might occur as major complications following kidney transplantation. Thus, the identification of biomarkers for the IRI, AR, and/or DGF development becomes crucial as it may help to guide post-transplant management. Natural killer (NK) cells, hepatic interstitial T-lymphocytes (T-Li), and NK-T cells are crucial in both innate and adaptive immunity after abdominal solid organ transplantation. Hence, the aim of this study was to evaluate the impact of the immune system after graft reperfusion during KT in adults in order to identify predictive biomarkers.

METHODS

The NK, T-Li, and NK-T phenotypes and concentrations were retrospectively analyzed in a consecutive series of liver perfusates obtained after organ procurement flushing the abdominal cavity recovered from deceased brain donors (DBDs). Their percentage was compared with the renal transplant recipients' characteristics with kidneys taken from the same DCDs. The hepatic perfusate cells were purified by density gradient centrifugation. Flow cytometric investigation was used to determine their phenotype with the following immunological markers in order to determine the relative percentage of T-Li, NK-T, and NK cells: CD3, CD4, CD8, and CD56.

RESULTS

42 DBDs' liver perfusates were analyzed. The related clinical outcomes of kidney transplant recipients from 2010 to 2020 performed at our Institute were evaluated. Time in days of delayed functional recovery of transplanted kidneys (DGF) (p = 0.02) and the onset of secondary infection from a cytomegalovirus (p = 0.03) were significantly associated with the T-Li percentage. An increased relative risk (HR) of organ survival was significantly associated with the percent cell concentration of T-Li and time to DGF, on COX analysis, were (HR = 1.038, p = 0.04; and HR = 1.029, p = 0.01, respectively). None relevant clinical outcomes in kidney transplant patients were associated with the specificity of the NK and NK-T cell proportions.

CONCLUSIONS

A new potential role of T-Li cells was detected in the context of hepatic perfusate from DBDs. It could detect potential impacts in organ allocation, surgical procuring techniques, and in the analysis of IRI pathophysiological events.

Outcomes of Kidney Perfusion Techniques in Transplantation from Deceased Donors: A Systematic Review and Meta-Analysis

The high demand for organs in kidney transplantation and the expansion of the donor pool have led to the widespread implementation of machine perfusion technologies. In this study, we aim to provide an up-to-date systematic review of the developments in this expanding field over the past 10 years, with the aim of answering the question: "which perfusion technique is the most promising technique in kidney transplantation?" A systematic review of the literature related to machine perfusion in kidney transplantation was performed. The primary outcome measure was delayed graft function (DGF), and secondary outcomes included rates of rejection, graft survival, and patient survival rates after 1 year. Based on the available data, a meta-analysis was performed. The results were compared with data from static cold storage, which is still the standard of care in many centers worldwide. A total of 56 studies conducted in humans were included, and 43 studies reported outcomes of hypothermic machine perfusion (HMP), with a DGF rate of 26.4%. A meta-analysis of 16 studies showed significantly lower DGF rates in the HMP group compared to those of static cold storage (SCS). Five studies reported outcomes of hypothermic machine perfusion + O₂, with an overall DGF rate of 29.7%. Two studies explored normothermic machine perfusion (NMP). These were pilot studies, designed to assess the feasibility of this perfusion approach in the clinical setting. Six studies reported outcomes of normothermic regional perfusion (NRP). The overall incidence of DGF was 71.5%, as it was primarily used in uncontrolled DCD (Maastricht category I-II). Three studies comparing NRP to in situ cold perfusion showed a significantly lower rate of DGF with NRP. The systematic review and meta-analysis provide evidence that dynamic preservation strategies can improve outcomes following kidney transplantation. More recent approaches such as normothermic machine perfusion and hypothermic machine perfusion + O₂ do show promising results but need further results from the clinical setting. This study shows that the implementation of perfusion strategies could play an important role in safely expanding the donor pool.

Knowing When to Ignore the Numbers: Single-Center Experience Transplanting Deceased Donor Kidneys with Poor Perfusion Parameters

BACKGROUND

Hypothermic machine perfusion is frequently used in evaluating marginal kidneys with poor perfusion parameters (PPP) contributing to delays in kidney placement or discard. We examined outcomes in deceased donor kidney transplants with PPP compared with those with optimal perfusion parameters (OPP).

STUDY DESIGN

We conducted a retrospective single-center cohort study from 2001 to 2021 comparing PPP (n = 91) with OPP (n = 598) deceased donor kidney transplants. PPP was defined as terminal flow ≤80 mL/min and terminal resistance ≥0.40 mmHg/mL/min. OPP was defined as terminal flow ≥120 mL/min and terminal resistance ≤0.20 mmHg/mL/min.

RESULTS

Mean terminal flow was PPP 66 ± 16 vs OPP 149 ± 21 mL/min and resistance was PPP 0.47 ± 0.10 vs OPP 0.15 ± 0.04 mmHg/mL/min (both p < 0.001). Donor age, donation after cardiac death, and terminal serum creatinine levels were similar between groups. Mean Kidney Donor Profile Index was higher among PPP donors (PPP 65 ± 23% vs OPP 52 ± 27%, p < 0.001). The PPP transplant group had more females and lower weight and BMI. Delayed graft function was comparable (PPP 32% vs OPP 27%, p = 0.33) even though cold ischemia times trended toward longer in PPP kidneys (PPP 28 ± 10 vs OPP 26 ± 9 hours, p = 0.09). One-year patient survival (PPP 98% vs OPP 97%, p = 0.84) and graft survival (PPP 91% vs OPP 92%, p = 0.23) were equivalent. PPP did predict inferior overall and death-censored graft survival long-term (overall hazard ratio 1.63, 95% CI 1.19 to 2.23 and death-censored hazard ratio 1.77, 95% CI 1.15 to 2.74). At 1 year, the estimated glomerular filtration rate was higher with OPP kidneys (PPP 40 ± 17 vs OPP 52 ± 19 mL/min/1.73 m 2 , p < 0.001).

CONCLUSIONS

Short-term outcomes in PPP kidneys were comparable to OPP kidneys despite higher Kidney Donor Profile Index and longer cold ischemia times, suggesting a role for increased utilization of these organs with careful recipient selection.

Preservation of Organs to Be Transplanted: An Essential Step in the Transplant Process

Organ transplantation remains the treatment of last resort in case of failure of a vital organ (lung, liver, heart, intestine) or non-vital organ (essentially the kidney and pancreas) for which supplementary treatments exist. It remains the best alternative both in terms of quality-of-life and life expectancy for patients and of public health expenditure. Unfortunately, organ shortage remains a widespread issue, as on average only about 25% of patients waiting for an organ are transplanted each year. This situation has led to the consideration of recent donor populations (deceased by brain death with extended criteria or deceased after circulatory arrest). These organs are sensitive to the conditions of conservation during the ischemia phase, which have an impact on the graft’s short- and long-term fate. This evolution necessitates a more adapted management of organ donation and the optimization of preservation conditions. In this general review, the different aspects of preservation will be considered. Initially done by hypothermia with the help of specific solutions, preservation is evolving with oxygenated perfusion, in hypothermia or normothermia, aiming at maintaining tissue metabolism. Preservation time is also becoming a unique evaluation window to predict organ quality, allowing repair and/or optimization of recipient choice.