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.

Disparate Formulations for Machine Perfusion: A Survey of Organ Procurement Organizations' Medication Additives and Outcome Analyses

OBJECTIVES

Machine perfusionfor kidney preservation is a common practice. There is no consensus on the best formula for perfusion solutions. We aimed to discern the additives that organ procurement organizations in the United States include in their perfusate and the impact of these additives on transplant outcomes.

MATERIALS AND METHODS

A telephone survey of all 58 organ procurement organizations in the United States regarding additives to their perfusion solutions was conducted. The survey data were merged with transplant recipient outcome data from the United Network for Organ Sharing database.The final analysis included perfused kidneys between January 2014 and March 2019. Logistic regressions were performed to investigate whether a particular perfusion formula was associated with delayed graft function, primary nonfunction, or early graft failure.

RESULTS

Additives correlated with decreased rates of graft failure were mannitol in all kidneys and kidneys of lower quality (P < .01) and penicillin/ampicillin in all kidneys (P < .05). Additives associated with increased graft failure regardless of type included verapamil in all kidneys (P < .05) and kidneys of lower quality (P < .01) and arginine with glutathione in all kidneys and low-quality kidneys alone (P < .01).

CONCLUSIONS

Further outcomes research and standardized guidelines for additives in machine perfusion of kidneys across all organ procurement organizations are needed.

How Machine Perfusion Ameliorates Hepatic Ischaemia Reperfusion Injury

The increasing disparity between the number of patients listed for transplantation and the number of suitable organs has led to the increasing use of extended criteria donors (ECDs). ECDs are at increased risk of developing ischaemia reperfusion injury and greater risk of post-transplant complications. Ischaemia reperfusion injury is a major complication of organ transplantation defined as the inflammatory changes seen following the disruption and restoration of blood flow to an organ—it is a multifactorial process with the potential to cause both local and systemic organ failure. The utilisation of machine perfusion under normothermic (37 degrees Celsius) and hypothermic (4–10 degrees Celsius) has proven to be a significant advancement in organ preservation and restoration. One of the key benefits is its ability to optimise suboptimal organs for successful transplantation. This review is focused on examining ischaemia reperfusion injury and how machine perfusion ameliorates the graft’s response to this.

Renal Resistance Trend During Hypothermic Machine Perfusion Correlates With Preimplantation Biopsy Score in Transplantation of Kidneys From Extended Criteria Donors

BACKGROUND

Graft quality from extended criteria donors (ECDs) is extremely wide, and a reliable evaluation parameter is required. So far, biopsy is widely used to evaluate ECD organs and to decide whether double (DKT) or single (SKT) kidney transplantation should be performed. The aim of this study is to compare renal resistance (RR) trend during hypothermic machine perfusion (HMP) with a preimplantation biopsy score.

METHODS

From December 2014 to April 2020, HMP has been systematically applied to all organs from ECDs for at least 3 hours. All grafts underwent a preimplantation biopsy histologic assessment with Karpinski's score. SKTs or DKTs were performed accordingly. RR trend during the first 180 minutes of HMP was compared with the biopsy score.

RESULTS

Eighty-three kidneys were used to perform 57 transplantations (31 SKTs and 26 DKTs). A biopsy confirmed suitability for transplantation in all cases, and the median score was 4 (range, 2-7). Kidneys with a score of 5 to 7 had significantly higher RR value than kidneys with a score of 0 to 4 at basal time (3.35 vs 2.71; P = .074), at 60 minutes (1.24 vs 0.94; P = .031), at 120 minutes (1.10 vs 0.81; P = .010), and at 180 minutes (1.00 vs 0.77; P = .022). A cutoff value of RR ≥0.88 at 120 minutes of perfusion had the best sensibility and specificity (0.71 and 0.75, respectively) to discriminate kidneys with a score of 5 to 7 from kidneys with a score of 0 to 4. No differences were found in postoperative outcomes between SKT and DKT recipients.

CONCLUSIONS

RR trend during HMP correlates with the histologic score in ECD kidneys and can be used as a reliable parameter to evaluate graft quality.

Oxygenated End-Hypothermic Machine Perfusion in Expanded Criteria Donor Kidney Transplant: A Randomized Clinical Trial

Importance

Continuous hypothermic machine perfusion during organ preservation has a beneficial effect on graft function and survival in kidney transplant when compared with static cold storage (SCS).

Objective

To compare the effect of short-term oxygenated hypothermic machine perfusion preservation (end-HMPo2) after SCS vs SCS alone on 1-year graft survival in expanded criteria donor kidneys from donors who are brain dead.

Design, Setting, and Participants

In a prospective, randomized, multicenter trial, kidneys from expanded criteria donors were randomized to either SCS alone or SCS followed by end-HMPo2 prior to implantation with a minimum machine perfusion time of 120 minutes. Kidneys were randomized between January 2015 and May 2018, and analysis began May 2019. Analysis was intention to treat.

Interventions

On randomization and before implantation, deceased donor kidneys were either kept on SCS or placed on HMPo2.

Main Outcome and Measures

Primary end point was 1-year graft survival, with delayed graft function, primary nonfunction, acute rejection, estimated glomerular filtration rate, and patient survival as secondary end points.

Results

Centers in 5 European countries randomized 305 kidneys (median [range] donor age, 64 [50-84] years), of which 262 kidneys (127 [48.5%] in the end-HMPo2 group vs 135 [51.5%] in the SCS group) were successfully transplanted. Median (range) cold ischemia time was 13.2 (5.1-28.7) hours in the end-HMPo2 group and 12.9 (4-29.2) hours in the SCS group; median (range) duration in the end-HMPo2 group was 4.7 (0.8-17.1) hours. One-year graft survival was 92.1% (n = 117) in the end-HMPo2 group vs 93.3% (n = 126) in the SCS group (95% CI, -7.5 to 5.1; P = .71). The secondary end point analysis showed no significant between-group differences for delayed graft function, primary nonfunction, estimated glomerular filtration rate, and acute rejection.

Conclusions and Relevance

Reconditioning of expanded criteria donor kidneys from donors who are brain dead using end-HMPo2 after SCS does not improve graft survival or function compared with SCS alone. This study is underpowered owing to the high overall graft survival rate, limiting interpretation.

Trial Registration

isrctn.org Identifier: ISRCTN63852508.

Hypothermic Machine Perfusion of Kidneys Compensates for Extended Storage Time: A Single Intervention With a Significant Impact

INTRODUCTION

Delayed graft function (DGF) adversely affects graft survival and function. Machine perfusion (MP) improves DGF rate and may compensate for extended storage time.

MATERIAL AND METHODS

In this single-center cohort study, we included 193 consecutive kidney transplantations. MP was used in 78 kidneys (36%) and static cold storage (CS) in 115 kidneys (64%). CS kidneys were transplanted first followed by MP kidneys if stored differently. Pairs of kidneys from the same donor were subjected for subgroup analysis and included 58 pairs. The primary endpoints were the rate of DGF and 1- and 5-year graft survival. The secondary endpoints were the rate of the primary nonfunction, mortality, acute rejection, duration of DGF, and 5-year estimated glomerular filtration rate.

RESULTS

Median cold ischemia time (CIT) was significantly different between the MP and CS groups (24 vs 20 hours, P < .05). MP significantly reduced the rate of DGF (MP vs CS: 21.8% vs 42.6%, P < .05, odds ratio 0.34, 95% confidence interval 0.17-0.67) with no impact on overall 1- and 5-year survival rates. Storage method did not affect the duration of DGF, mortality rate, acute rejection, or the 5-year estimated glomerular filtration rate.

CONCLUSIONS

Hypothermic pulsatile MP significantly reduced the rate of DGF in kidneys transplanted with CIT equal to or longer than 12 hours. It is safe and may compensate for longer storage time.

Preimplantation Histological Score Associates with 6-Month GFR in Recipients of Perfused, Older Kidney Grafts: Results from a Pilot Study

BACKGROUND

Biopsy-guided selection of older kidneys safely expands the organ pool, and pretransplant perfusion improves the preservation of these fragile organs. Herein, we studied morphofunctional variables associated with graft outcomes in perfused, histologically evaluated older kidneys.

METHODS

This single-center prospective cohort pilot study evaluated the relationships between preimplantation histologic scores and renal perfusion parameters during hypothermic, pulsatile, machine perfusion (MP) and assessed whether these morphofunctional parameters associated with GFR (iohexol plasma clearance) at 6 months after transplantation in 20 consecutive consenting recipients of a biopsy-guided single or dual kidney transplant from >60-year-old deceased donors.

RESULTS

The donor and recipient age was 70.4 ± 6.5 and 63.6 ± 7.9 years (p = 0.005), respectively. The kidney donor profile index (KDPI) was 93.3 ± 8.4% (>80% in 19 cases), histologic score 4.4 ± 1.4, and median (IQR) cold ischemia time 19.8 (17.8-22.8 h; >24 h in 5 cases). The 6-month GFR was 41.2 (34.9-55.7) mL/min. Vascular resistances positively correlated with global histologic score (p = 0.018) at MP start and then decreased from 0.88 ± 0.43 to 0.36 ± 0.13 mm Hg/mL/min (p < 0.001) in parallel with a three-fold renal flow increase from 24.0 ± 14.7 to 74.7 ± 31.8 mL/min (p < 0.001). Consistently, vascular resistance reductions positively correlated with global histologic score (p = 0.009, r = -0.429). Unlike KDPI or vascular resistances, histologic score was independently associated with 6-month GFR (beta standardized coefficient: -0.894, p = 0.005).

CONCLUSIONS

MP safely improves graft perfusion, particularly in kidneys with severe histologic changes that would not be considered for transplantation because of high KDPI. The preimplantation histologic score associates with the functional recovery of older kidneys even in the context of a standardized program of pulsatile perfusion.

Combination of mesenchymal stromal cells and machine perfusion is a novel strategy for organ preservation in solid organ transplantation

Organ preservation is a prerequisite for an urgent increase in the availability of organs for solid organ transplantation (SOT). An increasing amount of expanded criteria donor (ECD) organs are used clinically. Currently, the paradigm of organ preservation is shifting from simple reduction of cellular metabolic activity to maximal simulation of an ex vivo physiological microenvironment. An ideal organ preservation technique should not only preserve isolated organs but also offer the possibility of rehabilitation and evaluation of organ function prior to transplantation. Based on the fact that mesenchymal stromal cells (MSCs) possess strong regeneration properties, the combination of MSCs with machine perfusion (MP) is expected to be superior to conventional preservation methods. In recent years, several studies have attempted to use this strategy for SOT showing promising outcomes. With better organ function during ex vivo preservation and the potential of utilization of organs previously deemed untransplantable, this strategy is meaningful for patients with organ failure to help overcome organ shortage in the field of SOT.

Safety and feasibility of 2 h of normothermic machine perfusion of donor kidneys in the Eurotransplant Senior Program

Background

The 5-year graft survival rate of donor kidneys transplanted in the Eurotransplant Senior Program (ESP) is only 47 per cent. Normothermic machine perfusion (NMP) may be a new preservation technique that improves graft outcome. This pilot study aimed to assess safety and feasibility of this technique within the ESP.

Methods

Recipients were eligible for inclusion if they received a donor kidney within the ESP. Donor kidneys underwent 2 h of oxygenated NMP with a red cell-based solution at 37°C, additional to standard-of-care preservation (non-oxygenated hypothermic machine perfusion). The primary outcome was the safety and feasibility of NMP. As a secondary outcome, graft outcome was investigated and compared with that in a historical group of patients in the ESP and the contralateral kidneys.

Results

Eleven patients were included in the NMP group; the function of eight kidneys could be compared with that of the contralateral kidney. Fifty-three patients in the ESP, transplanted consecutively between 2016 and 2018, were included as controls. No adverse events were noted, especially no arterial thrombosis or primary non-function of the transplants. After 120 min of oxygenated NMP, median flow increased from 117 (i.q.r. 80–126) to 215 (170–276) ml/min (P = 0.001). The incidence of immediate function was 64 per cent in the NMP group and 40 per cent in historical controls (P = 0.144). A significant difference in graft outcome was not observed.

Discussion

This pilot study showed NMP to be safe and feasible in kidneys transplanted in the ESP. A well powered study is warranted to confirm these results and investigate the potential advantages of NMP on graft outcome.

Comparison of machine perfusion versus cold storage in kidney transplant recipients from expanded criteria donors: a cohort-based study

BACKGROUND

Most studies comparing the efficacy of hypothermic machine perfusion (HMP) versus static cold storage (SCS) are based on short-term outcomes. We aimed to better evaluate the mid-term impact of HMP in patients receiving expanded criteria donor (ECD) kidneys.

METHODS

The analyses were based on the French Données Informatisées et VAlidées en Transplantation (DIVAT) observational cohort. Patients aged ≥45 years transplanted for the first or second times from an ECD donor since 2010 were studied. Our study reported the graft and/or patient survivals and the incidence of acute rejection episode. The Cox models and the Kaplan-Meier estimators, weighted on the propensity score, were used to study the times-to-events.

RESULTS

Among the 2019 included patients, 1073 were in the SCS group versus 946 in the HMP group. The mean life expectancy with functioning graft was 5.7 years [95% confidence interval (CI) 5.4-6.1] for the HMP cohort followed-up for 8 years post-transplantation versus 6.0 years (95% CI 5.7-6.2) for the SCS group. These mid-term results were comparable in the patients receiving grafts from donors aged ≥70 years and in the transplantations with cold ischaemia time ≥18 h.

CONCLUSIONS

Our study challenges the utility of using HMP to improve mid-term patient and graft survival. Nevertheless, the improvement of the short-term outcomes is indisputable. It is necessary to continue technological innovations to obtain long-term results.

Should kidney allografts from old donors be allocated only to old recipients?

In several deceased donor kidney allocation systems, organs from elderly donors are allocated primarily to elderly recipients. The Eurotransplant Senior Program (ESP) was implemented in 1999, and since then, especially in Europe, the use of organs from elderly donors has steadily increased. The proportion of ≥60-year-old donors reported to the Collaborative Transplant Study (CTS) by European centers has doubled, from 21% in 2000-2001 to 42% in 2016-2017. Therefore, in the era of organ shortage it is a matter of debate whether kidney organs from elderly donors should only be allocated to elderly recipients or whether <65-year-old recipients can also benefit from these generally as "marginal" categorized organs. To discuss this issue, a European Consensus Meeting was organized by the CTS on April 12, 2018, in Heidelberg, in which 36 experts participated. Based on available evidence, it was unanimously concluded that kidney organs from 65- to 74-year-old donors can also be allocated to 55- to 64-year-old recipients, especially if these organs are from donors with no history of hypertension, no increased creatinine, no cerebrovascular death, and no other reasons for defining a marginal donor, such as diabetes or cancer.

Renal Procurement: Techniques for Optimizing the Quality of the Graft in the Cadaveric Setting

PURPOSE OF REVIEW

Kidney transplantation is the best treatment for end-stage renal disease. However, due to organ shortage, suboptimal grafts are increasingly being used.

RECENT FINDINGS

We carried out a review on the methods and techniques of organ optimization in the cadaveric setting. Donor care is the first link in a chain of care. Right after brain death, there is a set of changes, of which hormonal and hemodynamic changes are the most relevant. Several studies have been conducted to determine which drugs to administer, although in most cases, the results are not definitive. The main goal seems rather achieve a set of biochemical and hemodynamic objectives. The ischemia-reperfusion injury is a critical factor for kidney damage in transplantation. One of the ways found to deal with this type of injury is preconditioning. Local and remote ischemic preconditioning has been studied for various organs, but studies on the kidney are scarce. A new promising area is pharmacological preconditioning, which is taking its first steps. Main surgical techniques were established in the late twentieth century. Some minor new features have been introduced to deal with anatomical variations or the emergence of donation after circulatory death. Finally, after harvesting, it is necessary to ensure the best conditions for the kidneys until the time of transplantation. Much has evolved since static cold preservation, but the best preservation conditions are yet to be determined. Conservation in the cold has come to be questioned, and great results have appeared at temperatures closer to physiological.

Prospective randomized study comparing everolimus and mycophenolate sodium in de novo kidney transplant recipients from expanded criteria deceased donor

The optimal immunosuppressive regimen for recipients of expanded criteria donor (ECD) kidneys has not been identified. In this single-center study, 171 recipients of ECD kidney transplants were randomized to receive antithymocyte globulin induction, and delayed introduction of reduced dose tacrolimus, prednisone and everolimus (r-ATG/EVR, n = 88), or mycophenolate (r-ATG/MPS, n = 83). No cytomegalovirus (CMV) pharmacological prophylaxis was used. The primary endpoint was the incidence of CMV infection/disease at 12 months. Secondary endpoints included treatment failure [first biopsy-proven acute rejection (BPAR), graft loss, or death] and safety. Patients treated with EVR showed a 89% risk reduction (13.6 vs. 71.6%; HR 0.11, 95% CI 0.06-0.220, P < 0.001) in the incidence of first CMV infection/disease. Incidences of BPAR (16% vs. 5%, P = 0.021), graft loss (11% vs. 1%, P = 0.008), death (10% vs. 1%, P = 0.013), and treatment discontinuation (40% vs. 28%, P = 0.12) were higher in the r-ATG/EVR, leading to premature study termination. Mean glomerular filtration rate was lower in r-ATG/EVR (31.8 ± 18.8 vs. 42.6 ± 14.9, P < 0.001). In recipients of ECD kidney transplants receiving no CMV pharmacological prophylaxis, the use of everolimus was associated with higher treatment failure compared with mycophenolate despite the significant reduction in the incidence of CMV infection/disease (ClinicalTrials.gov.NCT01895049).

Machine Perfusion for Abdominal Organ Preservation: A Systematic Review of Kidney and Liver Human Grafts

Introduction: To match the current organ demand with organ availability from the donor pool, there has been a shift towards acceptance of extended criteria donors (ECD), often associated with longer ischemic times. Novel dynamic preservation techniques as hypothermic or normothermic machine perfusion (MP) are increasingly adopted, particularly for organs from ECDs. In this study, we compared the viability and incidence of reperfusion injury in kidneys and livers preserved with MP versus Static Cold Storage (SCS). Methods: Systematic review and meta-analysis with a search performed between February and March 2019. MEDLINE, EMBASE and Transplant Library were searched via OvidSP. The Cochrane Library and The Cochrane Central Register of Controlled Trials (CENTRAL) were also searched. English language filter was applied. Results: the systematic search generated 10,585 studies, finally leading to a total of 30 papers for meta-analysis of kidneys and livers. Hypothermic MP (HMP) statistically significantly lowered the incidence of primary nonfunction (PMN, p = 0.003) and delayed graft function (DGF, p < 0.00001) in kidneys compared to SCS, but not its duration. No difference was also noted for serum creatinine or eGFR post-transplantation, but overall kidneys preserved with HMP had a significantly longer one-year graft survival (OR: 1.61 95% CI: 1.02 to 2.53, p = 0.04). Differently from kidneys where the graft survival was affected, there was no significant difference in primary non function (PNF) for livers stored using SCS for those preserved by HMP and NMP. Machine perfusion demonstrated superior outcomes in early allograft dysfunction and post transplantation AST levels compared to SCS, but however, only HMP was able to significantly decrease serum bilirubin and biliary stricture incidence compared to SCS. Conclusions: MP improves DGF and one-year graft survival in kidney transplantation; it appears to mitigate early allograft dysfunction in livers, but more studies are needed to prove its potential superiority in relation to PNF in livers.

Combined Ex Vivo Hypothermic and Normothermic Perfusion for Assessment of High-risk Deceased Donor Human Kidneys for Transplantation

Background

Despite careful clinical examination, procurement biopsy and assessment on hypothermic machine perfusion, a significant number of potentially useable deceased donor kidneys will be discarded because they are deemed unsuitable for transplantation. Ex vivo normothermic perfusion (EVNP) may be useful as a means to further assess high-risk kidneys to determine suitability for transplantation.

Methods

From June 2014 to October 2015, 7 kidneys (mean donor age, 54.3 years and Kidney Donor Profile Index, 79%) that were initially procured with the intention to transplant were discarded based on a combination of clinical findings, suboptimal biopsies, long cold ischemia time (CIT) and/or poor hypothermic perfusion parameters. They were subsequently placed on EVNP using oxygenated packed red blood cells and supplemental nutrition for a period of 3 hours. Continuous hemodynamic and functional parameters were assessed.

Results

After a mean CIT of 43.7 hours, all 7 kidneys appeared viable on EVNP with progressively increasing renal blood flow over the 3-hour period of perfusion. Five of the 7 kidneys had excellent macroscopic appearance, rapid increase in blood flow to 200 to 250 mL/min, urine output of 40 to 260 mL/h and increasing creatinine clearance.

Conclusions

Favorable perfusion characteristics and immediate function after a 3-hour course of EVNP suggests that high-risk kidneys subjected to long CIT may have been considered for transplantation. The combined use of ex vivo hypothermic and normothermic perfusion may be a useful strategy to more adequately assess and preserve high-risk kidneys deemed unsuitable for transplantation. A clinical trial will be necessary to validate the usefulness of this approach.

The combined use of ex vivo hypothermic and normothermic perfusion may be a useful strategy to more adequately assess and preserve high-risk kidneys deemed unsuitable for transplantation.

Machine perfusion versus cold storage in renal preservation of deceased donors with brain death: systematic review and meta-analysis

With the increasing use of machine perfusion in kidney transplantation, it has been observed that dynamic ischemia correlates with the improvement of organ preservation. In this context, we performed a systematic review that aimed to evaluate the efficacy of the portable machine perfusion (LifePort Kidney Transporter Machine®), used in Brazil, compared to cold storage, regarding the delayed graft function of deceased donors with brain death. Literature search was carried out in LILACS, MEDLINE via PubMed, Scopus, Clarivate Analytics, Cochrane Library, Embase, and SciELO, as well as in Google Scholar manually. The systematic review consisted only of randomized clinical trials. For meta-analysis, relative risk and odds ratio were evaluated. Eighty-six documents were identified and two papers from European and Brazilian groups were selected at the end, with eligibility criteria for meta-analysis. In these, 374 kidneys were assigned to machine perfusion and 374 kidneys were assigned to cold storage. Delayed graft function was observed in 84 and 110 patients, respectively. In meta-analysis, a risk ratio of 0.7568 (p=0.0151) and an odds ratio of 0.6665 (p=0.0225) were obtained, both with a 95% confidence interval. Machine perfusion reduced the incidence of delayed graft function of deceased donors with brain death.

Machine preservation of donor kidneys in transplantation

With increasing demands for 'less than ideal' kidneys for transplantation, machine perfusion of kidneys has been utilized to improve the preservation of kidneys during storage. Hypothermic machine perfusion (HMP) of renal allografts has been shown to reduce delayed graft function rates in both expanded criteria and donation after cardiac death renal allografts. However, the beneficial impact upon long-term graft function is unclear. There has been emerging evidence that both subnormothermic (room temperature) and normothermic machine perfusion (NMP) of allografts have beneficial effects with regards to early graft function, survival and injury in pre-clinical and early clinical studies. Additionally, machine perfusion allows functional assessment of the organ prior to transplantation. Ultimately, the greatest benefit of machine perfusion may be the ability to treat the organ with agents to protect the graft against ischemia reperfusion injury, while awaiting transplantation.

The Benefits of Hypothermic Machine Preservation and Short Cold Ischemia Times in Deceased Donor Kidneys

BACKGROUND

Hypothermic machine perfusion (HMP) of deceased donor kidneys is associated with better outcome when compared to static cold storage (CS). Nevertheless, there is little evidence whether kidneys with short cold ischemia time (CIT) also benefit from HMP and whether HMP can safely extend CIT.

METHODS

We analyzed prospectively collected data from the Machine Preservation Trial, an international randomized controlled trial. Seven hundred fifty-two consecutive renal transplants were included: 1 kidney of each of the 376 donors was preserved by HMP, the contralateral organ was preserved by CS.

RESULTS

The mean CIT was 3:05 PM (SD, 4:58 AM). A subgroup analysis was performed, groups were based on CIT duration: 0 to 10 hours, 10 to 15 hours, 15 to 20 hours, or 20 hours or longer. Delayed graft function (DGF) incidence in the subgroup with up to 10 hours CIT was 6.0% (N = 3/50) in the HMP arm and 28.1% (N = 18/64) in the CS arm (univariable P = 0.002; multivariable odds ratio [OR], 0.02; P = 0.007). Cold ischemia time remained an independent risk factor for DGF for machine perfused kidneys recovered from donation after brain death donors (OR, 1.06; 95% confidence interval [CI], 1.017-1.117; P = 0.008), donation after circulatory death donors (OR, 1.13; 95% CI, 1.035-1.233; P = 0.006) and expanded criteria donors (OR, 1.14; 95% CI, 1.057-1.236; P = 0.001).

CONCLUSIONS

In conclusion, HMP resulted in remarkably lower rates of DGF in renal grafts that were transplanted after a short CIT. Also, CIT remained an independent risk factor for DGF in HMP-preserved kidneys.

Machine perfusion preservation versus static cold storage for deceased donor kidney transplantation

BACKGROUND

Kidney transplantation is the optimal treatment for end-stage kidney disease. Retrieval, transport and transplant of kidney grafts causes ischaemia reperfusion injury. The current accepted standard is static cold storage (SCS) whereby the kidney is stored on ice after removal from the donor and then removed from the ice box at the time of implantation. However, technology is now available to perfuse or "pump" the kidney during the transport phase or at the recipient centre. This can be done at a variety of temperatures and using different perfusates. The effectiveness of treatment is manifest clinically as delayed graft function (DGF), whereby the kidney fails to produce urine immediately after transplant.

OBJECTIVES

To compare hypothermic machine perfusion (HMP) and (sub)normothermic machine perfusion (NMP) with standard SCS.

SEARCH METHODS

We searched the Cochrane Kidney and Transplant Register of Studies to 18 October 2018 through contact with the Information Specialist using search terms relevant to this review. Studies in the Register are identified through searches of CENTRAL, MEDLINE, and EMBASE, conference proceedings, the International Clinical Trials Register (ICTRP) Search Portal and ClinicalTrials.gov.

SELECTION CRITERIA

All randomised controlled trials (RCTs) and quasi-RCTs comparing HMP/NMP versus SCS for deceased donor kidney transplantation were eligible for inclusion. All donor types were included (donor after circulatory (DCD) and brainstem death (DBD), standard and extended/expanded criteria donors). Both paired and unpaired studies were eligible for inclusion.

DATA COLLECTION AND ANALYSIS

The results of the literature search were screened and a standard data extraction form was used to collect data. Both of these steps were performed by two independent authors. Dichotomous outcome results were expressed as risk ratio (RR) with 95% confidence intervals (CI). Continuous scales of measurement were expressed as a mean difference (MD). Random effects models were used for data analysis. The primary outcome was incidence of DGF. Secondary outcomes included: one-year graft survival, incidence of primary non-function (PNF), DGF duration, long term graft survival, economic implications, graft function, patient survival and incidence of acute rejection.

MAIN RESULTS

No studies reported on NMP, however one ongoing study was identified.Sixteen studies (2266 participants) comparing HMP with SCS were included; 15 studies could be meta-analysed. Fourteen studies reported on requirement for dialysis in the first week post-transplant (DGF incidence); there is high-certainty evidence that HMP reduces the risk of DGF when compared to SCS (RR 0.77; 95% CI 0.67 to 0.90; P = 0.0006). HMP reduces the risk of DGF in kidneys from DCD donors (7 studies, 772 participants: RR 0.75; 95% CI 0.64 to 0.87; P = 0.0002; high certainty evidence), as well as kidneys from DBD donors (4 studies, 971 participants: RR 0.78, 95% CI 0.65 to 0.93; P = 0.006; high certainty evidence). The number of perfusions required to prevent one episode of DGF (number needed to treat, NNT) was 7.26 and 13.60 in DCD and DBD kidneys respectively. Studies performed in the last decade all used the LifePort machine and confirmed that HMP reduces the incidence of DGF in the modern era (5 studies, 1355 participants: RR 0.77, 95% CI 0.66 to 0.91; P = 0.002; high certainty evidence). Reports of economic analysis suggest that HMP can lead to cost savings in both the North American and European settings.Two studies reported HMP also improves graft survival however we were not able to meta-analyse these results. A reduction in incidence of PNF could not be demonstrated. The effect of HMP on our other outcomes (incidence of acute rejection, patient survival, hospital stay, long-term graft function, duration of DGF) remains uncertain.

AUTHORS' CONCLUSIONS

HMP is superior to SCS in deceased donor kidney transplantation. This is true for both DBD and DCD kidneys, and remains true in the modern era (studies performed in the last decade). As kidneys from DCD donors have a higher overall DGF rate, fewer perfusions are needed to prevent one episode of DGF (7.26 versus 13.60 in DBD kidneys).Further studies looking solely at the impact of HMP on DGF incidence are not required. Follow-up reports detailing long-term graft survival from participants of the studies already included in this review would be an efficient way to generate further long-term graft survival data.Economic analysis, based on the results of this review, would help cement HMP as the standard preservation method in deceased donor kidney transplantation.RCTs investigating (sub)NMP are required.

Hypothermic Machine Perfusion Versus Static Cold Storage in Deceased Donor Kidney Transplantation: A Systematic Review and Meta-Analysis of Randomized Controlled Trials

Static cold storage (SCS) and hypothermic machine perfusion (HMP) are two primary options for renal allograft preservation. Compared with SCS, HMP decreased the incidence of delayed graft function (DGF) and protected graft function. However, more evidence is still needed to prove the advantages of the HMP. In this study, the outcomes of kidney grafts from the two preservation methods were compared by conducting a systematic review and meta-analysis. Randomized controlled trials (RCTs) comparing the effect of hypothermic machine perfusion and static cold storage in deceased donor kidney transplantation were identified through searches of the MEDLINE, EMBASE, and Cochrane databases between January 1, 1980 and December 30, 2017. The primary endpoints were delayed graft function and graft survival. Secondary endpoints included primary non-function (PNF), graft renal function, duration of DGF, acute rejection, postoperative hospital stay and patient survival. Summary effects were calculated as risk ratio (RR) with 95% confidence interval (CI) or mean difference (MD) with 95% confidence intervals (CI). A total of 13 RCTs were included, including 2048 kidney transplant recipients. The results indicated that compared with SCS, HMP decreased the incidence of DGF (RR 0.78, 95% CI 0.69-0.87, P < 0.0001), and improved the graft survival at 3 years (RR 1.06, 95% CI 1.02-1.11, P = 0.009). There was no significant difference in other endpoints. HMP might be a more desirable method of preservation for kidney grafts. The long-term outcomes of kidney allografts stored by hypothermic machine perfusion still need to be further investigated.

Hypothermic Oxygenated Machine Perfusion of the Human Donor Pancreas

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Background

Transplantation of beta cells by pancreas or islet transplantation is the treatment of choice for a selected group of patients suffering from type 1 diabetes mellitus. Pancreata are frequently not accepted for transplantation, because of the relatively high vulnerability of these organs to ischemic injury. In this study, we evaluated the effects of hypothermic machine perfusion (HMP) on the quality of human pancreas grafts.

Methods

Five pancreata derived from donation after circulatory death (DCD) and 5 from donation after brain death (DBD) donors were preserved by oxygenated HMP. Hypothermic machine perfusion was performed for 6 hours at 25 mm Hg by separate perfusion of the mesenteric superior artery and the splenic artery. Results were compared with those of 10 pancreata preserved by static cold storage.

Results

During HMP, homogeneous perfusion of the pancreas could be achieved. Adenosine 5′-triphosphate concentration increased 6,8-fold in DCD and 2,6-fold in DBD pancreata. No signs of cellular injury, edema or formation of reactive oxygen species were observed. Islets of Langerhans with good viability and in vitro function could be isolated after HMP.

Conclusions

Oxygenated HMP is a feasible and safe preservation method for the human pancreas that increases tissue viability.

Hypothermic Machine Perfusion Results in a Marginal Kidney Transplant Programme

BACKGROUND

Hypothermic machine perfusion (HMP) of deceased donor kidneys is associated with a better outcome than static cold storage, predominantly in marginal donors. Nevertheless, there is little evidence supporting whether graft centre of origin and donor category impact HMP results.

OBJECTIVE

To identify factors impacting HMP in transplantation from marginal donors.

DESIGN, SETTING, AND PARTICIPANTS

Analysis of prospectively collected cohort data of expanded criteria donor (ECD) and donor after circulatory death (DCD) categories II and III was performed. A total of 214 adult recipients of first kidney transplantation with complete data and a minimum of 6-mo follow-up were included.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Delayed graft function (DGF) was defined as the lack of decrease in creatinine level in the first 48h. Graft loss was defined as return to dialysis or creatinine clearance <15ml/min/1.73m². Univariate and multivariate logistic regression analyses for DGF were constructed to identify independent risk factors. Recipient and graft survival (GS) analyses were conducted by Kaplan-Meier, and univariate and multivariate Cox regression analyses.

RESULTS AND LIMITATION

DGF occurred in 32.8% of imported and 20.5% of local grafts (p=0.059). Only donor category (DCD; odds ratio [OR]: 6.6, p=0.008) and haemodialysis (OR: 3.5, p=0.002) were significantly associated with DGF development. The 1-yr GS rate was 92.5% in the local donor group and 84.3% in the imported donor group (p=0.050). Multivariate analysis by Cox proportional hazards model identified only donor category (hazard ratio [HR] 10.99, p=0.001) and donor age (HR 1.07, p=0.005) as predictive variables for GS. The small sample size of the DCD group diminished the statistical power and did not permit a subgroup analysis to determine the impact of specific DCD category on HMP results.

CONCLUSIONS

DCD donor category, but not donor centre of origin, impacted DGF development and GS in the HMP of deceased donor kidneys.

PATIENT SUMMARY

Currently, the number of donors is insufficient to meet the demand for renal grafts. Expanded criteria for donation after brain death and donation after circulatory death (DCD) programmes have been developed as strategies to minimise this problem. Hypothermic machine perfusion has previously demonstrated its usefulness in expanded criteria donation and DCD preservation. DCD type and donor age increase the risk of graft loss.

Impact of machine perfusion after long static cold storage on delayed graft function incidence and duration and time to hospital discharge

Delayed graft function (DGF) is very high in our center (70%-80%), and we usually receive a kidney for transplant after more than 22 hours of static cold ischemia time (CIT). Also, there is an inadequate care of the donors, contributing to a high rate of DGF. We decided to test whether machine perfusion (MP) after a CIT improved the outcome of our transplant patients. We analyzed the incidence of DGF, its duration, and the length of hospital stay (LOS) in patients who received a kidney preserved with MP after a CIT (hybrid perfusion-HP). We included 54 deceased donors kidneys preserved with HP transplanted from Feb/13 to Jul/14, and compared them to 101 kidney transplants preserved by static cold storage (CS) from Nov/08 to May/12. The median pumping time was 11 hours. DGF incidence was 61.1% vs 79.2% (P = .02), median DGF duration was 5 vs 11 days (P < .001), and median LOS was 13 vs 18 days (P < .011), for the HP compared to CS group. The observed reduction of DGF with machine perfusion did not occur in donors over 50 years old. In the multivariate analysis, risk factors for DGF, adjusted for CIT, were donor age (OR, 1.04; P = .005) and the absence of use of MP (OR, 1.54; P = .051). In conclusion, the use of HP contributed to faster recovery of renal function and to a shorter length of hospital stay.

Early experience with hypothermic machine perfusion of living donor kidneys - a retrospective study

Although hypothermic machine perfusion (HMP) has been shown to be beneficial to deceased donor kidneys, the effect of HMP on living donor kidneys (LDK) is unknown. LDK are subjected to minutes of normothermic ischemia at the time of recovery. Comparison of 16 LDK preserved by HMP with 16 LDK preserved by static cold storage (SCS). Outcomes of interest are resistive indices (RI), both while on HMP and postoperatively, and creatinine clearance (CrCl). Injury markers NGAL and LDH were seen in the perfusate of LDK in amounts similar to what is found for donation after neurological determination of death kidneys. Compared to SCS kidneys, CrCl was significantly higher in the HMP group from days 2 through 7 post-transplant [ie: day 7 (78.8 ± 5.4 vs. 54.0 ± 4.6 ml/min, P = 0.005)]. CrCl at 1 year was higher in the HMP group (81.2 ± 5.8 vs. 70.0 ± 5.3 ml/min, P = 0.03). Early post-transplant RI was significantly lower in the HMP group (0.61 ± 0.02 vs. 0.71 ± 0.02, P < 0.0001). Our data support the assertion that injury does occur during LDK procurement and suggest that some of this injury may be reversed with HMP, resulting in more favorable early RI and graft function compared to SCS kidneys.

Randomized Trial of Machine Perfusion Versus Cold Storage in Recipients of Deceased Donor Kidney Transplants With High Incidence of Delayed Graft Function

BACKGROUND

This study compared the use of static cold storage versus continuous hypothermic machine perfusion in a cohort of kidney transplant recipients at high risk for delayed graft function (DGF).

METHODS

In this national, multicenter, and controlled trial, 80 pairs of kidneys recovered from brain-dead deceased donors were randomized to cold storage or machine perfusion, transplanted, and followed up for 12 months. The primary endpoint was the incidence of DGF. Secondary endpoints included the duration of DGF, hospital stay, primary nonfunction, estimated glomerular filtration rate, acute rejection, and allograft and patient survivals.

RESULTS

Mean cold ischemia time was high but not different between the 2 groups (25.6 ± 6.6 hours vs 25.05 ± 6.3 hours, 0.937). The incidence of DGF was lower in the machine perfusion compared with cold storage group (61% vs. 45%, P = 0.031). Machine perfusion was independently associated with a reduced risk of DGF (odds ratio, 0.49; 95% confidence interval, 0.26-0.95). Mean estimated glomerular filtration rate tended to be higher at day 28 (40.6 ± 19.9 mL/min per 1.73 m² vs 49.0 ± 26.9 mL/min per 1.73 m²; P = 0.262) and 1 year (48.3 ± 19.8 mL/min per 1.73 m² vs 54.4 ± 28.6 mL/min per 1.73 m²; P = 0.201) in the machine perfusion group. No differences in the incidence of acute rejection, primary nonfunction (0% vs 2.5%), graft loss (7.5% vs 10%), or death (8.8% vs 6.3%) were observed.

CONCLUSIONS

In this cohort of recipients of deceased donor kidneys with high mean cold ischemia time and high incidence of DGF, the use of continuous machine perfusion was associated with a reduced risk of DGF compared with the traditional cold storage preservation method.

The Development of a Thin-Filmed Noninvasive Tissue Perfusion Sensor to Quantify Capillary Pressure Occlusion of Explanted Organs

A new thin-filmed perfusion sensor was developed using a heat flux gauge, thin-film thermocouple, and a heating element. This sensor, termed "CHFT+," is an enhancement of the previously established combined heat flux-temperature (CHFT) sensor technology predominately used to quantify the severity of burns [1]. The CHFT+ sensor was uniquely designed to measure tissue perfusion on explanted organs destined for transplantation, but could be functionalized and used in a wide variety of other biomedical applications. Exploiting the thin and semiflexible nature of the new CHFT+ sensor assembly, perfusion measurements can be made from the underside of the organ-providing a quantitative indirect measure of capillary pressure occlusion. Results from a live tissue test demonstrated, for the first time, the effects of pressure occlusion on an explanted porcine kidney. CHFT+ sensors were placed on top of and underneath 18 kidneys to measure and compare perfusion at perfusate temperatures of 5 and 20 °C. The data collected show a greater perfusion on the topside than the underside of the specimen for the length of the experiment. This indicates that the pressure occlusion is truly affecting the perfusion, and, thus, the overall preservation of explanted organs. Moreover, the results demonstrate the effect of preservation temperature on the tissue vasculature. Focusing on the topside perfusion only, the 20 °C perfusion was greater than the 5 °C perfusion, likely due to the vasoconstrictive response at the lower perfusion temperatures.

Transplantation of Declined Liver Allografts Following Normothermic Ex-Situ Evaluation

The demand for liver transplantation (LT) exceeds supply, with rising waiting list mortality. Utilization of high-risk organs is low and a substantial number of procured livers are discarded. We report the first series of five transplants with rejected livers following viability assessment by normothermic machine perfusion of the liver (NMP-L). The evaluation protocol consisted of perfusate lactate, bile production, vascular flows, and liver appearance. All livers were exposed to a variable period of static cold storage prior to commencing NMP-L. Four organs were recovered from donors after circulatory death and rejected due to prolonged donor warm ischemic times; one liver from a brain-death donor was declined for high liver function tests (LFTs). The median (range) total graft preservation time was 798 (range 724-951) min. The transplant procedure was uneventful in every recipient, with immediate function in all grafts. The median in-hospital stay was 10 (range 6-14) days. At present, all recipients are well, with normalized LFTs at median follow-up of 7 (range 6-19) months. Viability assessment of high-risk grafts using NMP-L provides specific information on liver function and can permit their transplantation while minimizing the recipient risk of primary graft nonfunction. This novel approach may increase organ availability for LT.

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.

Does machine perfusion decrease ischemia reperfusion injury?

In 1990's, use of machine perfusion for organ preservation has been abandoned because of improvement of preservation solutions, efficient without perfusion, easy to use and cheaper. Since the last 15 years, a renewed interest for machine perfusion emerged based on studies performed on preclinical model and seems to make consensus in case of expanded criteria donors or deceased after cardiac death donations. We present relevant studies highlighted the efficiency of preservation with hypothermic machine perfusion compared to static cold storage. Machines for organ preservation being in constant evolution, we also summarized recent developments included direct oxygenation of the perfusat. Machine perfusion technology also enables organ reconditioning during the last hours of preservation through a short period of perfusion on hypothermia, subnormothermia or normothermia. We present significant or low advantages for machine perfusion against ischemia reperfusion injuries regarding at least one primary parameter: risk of DFG, organ function or graft survival.

Hypothermic machine perfusion of kidneys retrieved from standard and high-risk donors

Hypothermic machine perfusion (HMP) of kidneys is a long-established alternative to static cold storage and has been suggested to be a better preservation method. Today, as our deceased donor profile continues to change towards higher-risk kidneys of lower quality, we are confronted with the limits of cold storage. Interest in HMP as a preservation technique is on the rise. Furthermore, HMP also creates a window of opportunity during which to assess the viability and quality of the graft before transplantation. The technology might also provide a platform during which the graft could be actively repaired, making it particularly attractive for higher-risk kidneys. We review the current evidence on HMP in kidney transplantation and provide an outlook for the use of the technology in the years to come.

Subnormothermic machine perfusion for preservation of porcine kidneys in a donation after circulatory death model

Machine perfusion for preservation led to compelling success for the outcome of renal transplantation. Further refinements of methods to decrease preservation injury remain an issue of high interest. This study investigates functional and morphological aspects of kidneys preserved by subnormothermic (20 °C) machine perfusion (SNTM) compared with oxygenated hypothermic machine perfusion (HMPox) and cold storage (CS) in a donation after circulatory death (DCD) model. After 30 min of warm ischaemia, porcine kidneys were randomly assigned to preservation for 7 h by CS, HMPox or SNTM. Afterwards, kidneys were reperfused for 2 h with autologous blood in vitro for assessment of function and integrity. Application of SNTM for preservation led to significantly higher blood flow and urine output compared with both other groups. SNTM led to a twofold increased creatinine clearance compared with HMPox and 10-fold increased creatinine clearance compared with CS. Structural integrity was best preserved by SNTM. In conclusion, this is the first study on SNTM for kidneys from DCD donors. SNTM seems to be a promising preservation method with the potential to improve functional parameters of kidneys during reperfusion.

Mechanisms and consequences of injury and repair in older organ transplants

Donor organ scarcity remains a significant clinical challenge in transplantation. Older organs, increasingly utilized to meet the growing demand for donor organs, have been linked to inferior transplant outcomes. Susceptibility to organ injury, reduced repair capacity, and increased immunogenicity are interrelated and impacted by physiological and pathological aging processes. Insights into the underlying mechanisms are needed to develop age-specific interventional strategies with regards to organ preservation, immunosuppression, and allocation. In this overview, we summarize current knowledge of injury and repair mechanisms and the effects of aging relevant to transplantation.

Kidneys at higher risk of discard: expanding the role of dual kidney transplantation

Half of the recovered expanded criteria donor (ECD) kidneys are discarded in the United States. A new kidney allocation system offers kidneys at higher risk of discard, Kidney Donor Profile Index (KDPI)>85%, to a wider geographic area to promote broader sharing and expedite utilization. Dual kidney transplantation (DKT) based on the KDPI is a potential option to streamline allocation of kidneys which otherwise would have been discarded. To assess the clinical utility of the KDPI in kidneys at higher risk of discard, we analyzed the OPTN/UNOS Registry that included the deceased donor kidneys recovered between 2002 and 2012. The primary outcomes were allograft survival, patient survival and discard rate based on different KDPI categories (<80%, 80-90% and >90%). Kidneys with KDPI>90% were associated with increased odds of discard (OR=1.99, 95% CI 1.74-2.29) compared to ones with KDPI<80%. DKTs of KDPI>90% were associated with lower overall allograft failure (HR=0.74, 95% CI 0.62-0.89) and better patient survival (HR=0.79, 95% CI 0.64-0.98) compared to single ECD kidneys with KDPI>90%. Kidneys at higher risk of discard may be offered in the up-front allocation system as a DKT. Further modeling and simulation studies are required to determine a reasonable KDPI cutoff percentile.

Hypothermic machine perfusion reduces delayed graft function and improves one-year graft survival of kidneys from expanded criteria donors: a meta-analysis

Background

Expanded criteria donors (ECDs) are currently accepted as potential sources to increase the donor pool and to provide more chances of kidney transplantation for elderly recipients who would not survive long waiting periods. Hypothermic machine perfusion (HMP) is designed to mitigate the deleterious effects of simple cold storage (CS) on the quality of preserved organs, particularly when the donor is in a marginal status.

Methods

We compared the transplant outcomes in patients receiving ECD kidneys with either HMP or CS graft preservation. Articles from the MEDLINE, EMBASE and Cochrane Library databases were searched and all studies reporting outcomes from HMP versus CS methods of kidney preservation were included in this meta-analysis. The parameters analyzed included the incidence of delayed graft function (DGF), primary non-function (PNF) and one-year graft and patient survival.

Results

A total of seven studies qualified for the review, involving 2374 and 8716 kidney grafts with HMP or CS preservation respectively, all from ECD donors. The incidence of delayed graft function (DGF) was significantly reduced with an odd ratio(OR) of 0.59 (95% CI 0.54–0.66, P<0.001) and one-year graft survival was significantly improved with an OR of 1.12 (95% CI 1.03–1.21, P = 0.005) in HMP preservation compared to CS. However, there was no difference in the incidence of PNF (OR 0.54, 95% CI 0.21–1.40, P = 0.20), and one-year patient survival (OR 0.98, 95% CI 0.94–1.02, P = 0.36) between HMP and CS preservation.

Conclusions

HMP was associated with a reduced incidence of DGF and an with increased one-year graft survival, but it was not associated with the incidence of PNF and one-year patient survival.

Systematic review and meta-analysis of hypothermic machine perfusion versus static cold storage of kidney allografts on transplant outcomes

BACKGROUND

Adequate preservation of renal allografts for transplantation is important for maintaining and improving transplant outcomes. There are two prevalent methods: hypothermic machine perfusion and static cold storage. The preferred method of storage, however, remains controversial. The objective was to review systematically the evidence comparing outcomes from these two modalities.

METHODS

A literature search was performed using MEDLINE, Embase, the Cochrane Library, the Transplant Library and the International Clinical Trials Registry Platform. The final date for searches was 30 November 2012. Studies were assessed for methodological quality. Summary effects were calculated as relative risk (RR) with 95 per cent confidence interval (c.i.). Randomized clinical trials (RCTs) and non-RCTs were included, but evaluated separately. Results from RCTs alone were used for meta-analysis.

RESULTS

Eighteen studies met the inclusion criteria, including seven RCTs (1475 kidneys) and 11 non-RCTs (728 kidneys). The overall risk of delayed graft function was lower with hypothermic machine perfusion than static cold storage (RR 0·81, 95 per cent c.i. 0·71 to 0·92; P = 0·002). There was no difference in the rate of primary non-function (RR 1·15, 0·46 to 2·90; P = 0·767). There was a faster initial fall in the level of serum creatinine with hypothermic machine perfusion in two RCTs, but not in another. There was no relationship between rates of acute rejection or patient survival and the method of preservation.

CONCLUSION

Data from the included studies suggest that hypothermic machine perfusion reduces delayed graft function compared with static cold storage. There was no difference in primary non-function, acute rejection, long-term renal function or patient survival. A difference in renal graft survival is uncertain.

Machine perfusion viability testing

PURPOSE OF REVIEW

Pretransplant assessment of kidney graft viability may help clinicians to decide whether to accept or discard a kidney for transplantation. With the increasing demand for donor kidneys and the increased use of marginal kidneys, the need of viability markers has increased to pursue superior transplant outcomes. Hypothermic machine perfusion (HMP) provides the theoretical opportunity to assess the viability of donor kidneys. We discuss the novel developments in viability testing during HMP and address the future prospects.

RECENT FINDINGS

HMP viability testing has focused on the analysis of machine perfusion parameters and perfusate biomarkers. Renal resistance and the biomarkers lactate dehydrogenase, aspartate transaminase, glutathione-S-transferase, N-acetyl-β-D-glucosaminidase, heart-type fatty acid binding protein, lipid peroxidation products, redox-active iron and IL-18 are correlated with transplant outcome in terms of development of delayed graft function or graft survival. However, they all lack adequate predictive value for transplant outcome. New techniques including contrast-enhanced ultrasound, three-dimensional ultrasound and magnetic resonance spectrometry are promising methods to test kidney viability during HMP, but their value has to be established. The introduction of normothermic machine perfusion offers other promising opportunities for viability testing.

SUMMARY

Machine perfusion characteristics and perfusate biomarkers have been extensively studied. They often correlate with the transplant outcome, but the present viability tests are not reliable predictors of transplant outcome. New developments in kidney graft viability assessment are necessary to have a chance of being clinically useful in the future.