Comparison of Pulsatile Perfusion and Cold Storage for Paired Kidney Allografts

Perfusion Techniques in Kidney Allograft Preservation to Reduce Ischemic Reperfusion Injury: A Systematic Review and Meta-Analysis

The limited supply and rising demand for kidney transplantation has led to the use of allografts more susceptible to ischemic reperfusion injury (IRI) and oxidative stress to expand the donor pool. Organ preservation and procurement techniques, such as machine perfusion (MP) and normothermic regional perfusion (NRP), have been developed to preserve allograft function, though their long-term outcomes have been more challenging to investigate. We performed a systematic review and meta-analysis to examine the benefits of MP and NRP compared to traditional preservation techniques. PubMed (MEDLINE), Embase, Cochrane, and Scopus databases were queried, and of 13,794 articles identified, 54 manuscripts were included (n = 41 MP; n = 13 NRP). MP decreased the rates of 12-month graft failure (OR 0.67; 95%CI 0.55, 0.80) and other perioperative outcomes such as delayed graft function (OR 0.65; 95%CI 0.54, 0.79), primary nonfunction (OR 0.63; 95%CI 0.44, 0.90), and hospital length of stay (15.5 days vs. 18.4 days) compared to static cold storage. NRP reduced the rates of acute rejection (OR 0.48; 95%CI 0.35, 0.67) compared to in situ perfusion. Overall, MP and NRP are effective techniques to mitigate IRI and play an important role in safely expanding the donor pool to satisfy the increasing demands of kidney transplantation.

Simultaneous Heart-kidney Transplant With Planned Delayed Implantation of the Kidney Graft After Ex Vivo Perfusion

BACKGROUND

Simultaneous heart-kidney transplant (SHK) is an established option for patients with severe heart failure and chronic kidney disease. Recent studies in simultaneous liver-kidney transplantation demonstrate favorable outcomes achieved by delaying implantation of the kidney for over 24 h. This report describes a case series of consecutive patients listed for SHK who had planned delayed implantation of the kidney graft.

METHODS

This case series represents a retrospective analysis of SHK patients extracted from the transplant database at a single center.

RESULTS

There were 7 patients who underwent SHK during the study period. In all cases, kidney grafts were maintained on hypothermic ex vivo pulsatile perfusion for delayed implantation (mean cold ischemia 53 h [range, 31-69]). The first 5 patients had 100% 1-y heart and kidney graft survival with good function. Patient 6 was unstable on extracorporeal membrane oxygenation post-heart transplant. The kidney was implanted at 69 h, and the patient died soon thereafter. Patient 7 was also unstable on extracorporeal membrane oxygenation after heart transplant. The decision was made to implant the kidney into a backup kidney recipient. The heart transplant recipient subsequently died several days later, whereas the kidney was successfully transplanted in the alternate candidate.

CONCLUSIONS

This case series highlights the potential utility of delayed kidney implantation in SHK patients. SHK with delayed renal transplant may provide an improved physiologic environment for renal transplant, which may result in improved early renal graft function. Delayed kidney transplant also provides the opportunity to transplant the kidney graft into an alternate candidate.

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.

Combined liver-kidney transplantation with positive crossmatch: Role of delayed kidney transplantation

BACKGROUND

Positive crossmatch (XM+) combined liver-kidney transplantation due to preformed donor-specific human leukocyte antigen antibodies has produced mixed results. We sought to understand the role of delayed kidney transplant approach in XM+ combined liver-kidney transplantations.

METHODS

XM+ combined liver-kidney transplantations were retrospectively reviewed. T- and B-cell XM, complement-dependent cytotoxic crossmatch, and flow cytometric crossmatch were performed prospectively.

RESULTS

Of 183 combined liver-kidney transplantations performed (2002-2019), 114 (62%) were with "delayed" kidney transplant approach and 19 (19 of 183, 10%) were XM+. Of 19 XM+ combined liver-kidney transplantations, kidney transplant was "delayed" in 14 by an average of 47 hours (range 24-64 hours) from liver transplant. There was a significant reduction in both class I (mean pre-liver transplant mean fluorescence intensity (MFI) 26,230 versus mean post-liver transplant and pre-delayed kidney transplant MFI 3,272, P = .01) and total MFI (mean pre-liver transplant MFI 27,233 vs mean post liver transplant and predelayed kidney transplant MFI 11,469, P = .01). However, there was no significant change in the MFI of class II donor-specific antibodies (mean pre-liver transplant MFI 17,899 versus post-liver transplant and pre-delayed kidney transplant MFI 14,341, P = .19). None of XM+ delayed kidney transplants had delayed graft function, and there was no antibody-mediated rejection. One-year patient survival for the XM+ combined liver-kidney transplantation with delayed kidney transplant approach was 92.9%, which is comparable to patient survival of XM- combined liver-kidney transplantation. Whereas patient survival in recipients before "delayed" approach ("simultaneous"; n = 5) was 40% when liver-kidney transplants were performed simultaneously (P = .06).

CONCLUSION

In sensitized combined liver-kidney transplantation recipients, the "delayed" kidney transplant approach is associated with a significant reduction in total and class I donor-specific antibodies after liver transplant before kidney transplant, enabling therapeutic interventions such as plasmapheresis, if needed, providing optimal outcomes similar to crossmatch recipients.

Impact of Recipient Age in Combined Liver-Kidney Transplantation: Caution Is Needed for Patients ≥70 Years

Elderly recipients (≥70 y) account for 2.6% of all liver transplants (LTs) in the United States and have similar outcomes as younger recipients. Although the rate of elderly recipients in combined liver-kidney transplant (CLKT) is similar, limited data are available on how elderly recipients perform after CLKT.

METHODS

We have previously shown excellent outcomes in CLKT using delayed kidney transplant (Indiana) Approach (mean kidney cold ischemia time = 53 ± 14 h). Between 2007 and 2018, 98 CLKTs were performed using the Indiana Approach at Indiana University (IU) and the data were retrospectively analyzed. Recipients were subgrouped based on their age: 18-45 (n = 16), 46-59 (n = 34), 60-69 (n = 40), and ≥70 years (n = 8).

RESULTS

Overall, more elderly patients received LT at IU (5.2%) when compared nationally (2.6%). The rate of elderly recipients in CLKT at IU was 8.2% (versus 2% Scientific Registry of Transplant Recipient). Recipient and donor characteristics were comparable between all age groups except recipient age and duration of dialysis. Patient survival at 1 and 3 years was similar among younger age groups, whereas patient survival was significantly lower in elderly recipients at 1 (60%) and 3 years (40%) (P = 0.0077). Control analyses (replicating Scientific Registry of Transplant Recipient's survival stratification: 18-45, 46-64, ≥65 y) showed similar patient survival in all age groups.

CONCLUSIONS

Although LT can be safely performed in elderly recipients, extreme caution is needed in CLKT due to the magnitude of operation.

Contrast Administration to the Deceased Kidney Donor Has No Impact on Post-Transplant Outcomes

BACKGROUND

Contrast-induced acute kidney injury may occur in patients undergoing imaging studies. This study reviews all deceased kidney donors at a single center during a 15-y period to determine if donor contrast exposure results in contrast-induced acute kidney injury in the donor or is associated with worse outcomes in the transplant recipient.

METHODS

Donor and recipient renal functions were recorded, including donor serum creatinine and recipient delayed graft function, creatinine clearance at 1 y, and early and late graft survival. Donor contrast exposure was recorded as the number of preprocurement contrasted studies.

RESULTS

Donor and recipient records were available for 1394 transplants (88%). There were 51% of donors who received any contrasted study (38%, one study; 12%, two studies, and 1%, three studies). Donor contrast exposure was not associated with significant differences in preprocurement serum creatinine levels. Post-transplant, donor contrast exposure was associated with risk of neither delayed graft function (4% for all) nor early kidney graft loss. Creatinine clearance at 1 y was equivalent. Five-year Cox regression demonstrated higher graft survival for contrast-exposed grafts (P = 0.03).

CONCLUSIONS

There is no negative effect of donor contrast administration on early and late kidney graft function. These findings included donor kidneys exposed to as many as three contrasted studies.

Outcomes of Deceased Donor Kidney Transplantation Using Expanded Criteria Donor Kidneys Following Pulsatile Preservation

Aim

We compared the outcomes of transplanting expanded criteria donor (ECD) kidneys undergoing machine perfusion (MP) versus cold storage (CS).

Material and methods

Data on all expanded criteria deceased donor kidney transplants performed at the University of Pittsburgh Medical Center from January 2003 through December 2012 were collected from an in-house electronic repository. There were 78 patients in the MP group and 101 patients in the CS group. The majority of the ECD kidneys were imported from other organ procurement organizations: 69 of 73 in the MP group (94.5%, 5 from unknown sources); and 90 of 99 in the CS group (91%), 2 from an unknown source). Most of the patients in the MP group (77 of 78) received a combination of MP and static CS. MP was performed just prior to transplantation in all MP patients. We used descriptive statistics to characterize our sample. We used logistic regression analysis to model the binary outcome of delayed graft function (DGF; i.e., “yes/no”) and Cox (proportional hazard) regression to model time until graft failure. The Kaplan-Meier product-limit method was used to estimate survival curves for graft and patient survival.

Results

A total of 179 transplants were done from ECD donors (MP, 78; CS, 101). The mean static cold storage time was 14 ± 4.1 hours and the mean machine perfusion time was 11.2 ± 6.3 hours in the MP group. The donor creatinine was higher (1.3 ± 0.6 mg/dl vs. 1.2 ± 0.4 mg/dl, p = 0.01) and the cold ischemia time was longer (28.9 ± 10 hours vs. 24 ± 7.9 hours, p = 0.0003) in the MP patients. There were no differences between the two groups in DGF rate (20.8% [MP] vs. 25.8% [CS], p = 0.46), six-year patient survival (74% [MP] vs. 63.2% [CS], p = 0.11), graft survival (64.3% [MP] vs. 51.5% [CS], p = 0.22), and serum creatinine levels (1.5 mg/dl vs. 1.5 mg/dl) on univariate analysis. On unadjusted analysis, MP subjects without DGF had longer graft survival compared to CS subjects with DGF (p < 0.0032) and MP subjects with DGF (p < 0.0005). MP subjects without DGF had longer death-censored graft survival compared to CS subjects with DGF (p < 0.0077) and MP subjects with DGF (p < 0.0016). However, on regression analysis, MP subjects had longer graft survival than CS subjects when DGF was not present. MP subjects without DGF had longer patient survival compared to CS subjects with DGF (p < 0.0289), on unadjusted analysis. MP subjects had a reduced risk of graft failure (hazard ratio [HR], 0.34; 95% confidence interval [CI], 0.17, 0.68) and death-censored graft failure (HR, 0.44; 95% CI, 0.19, 1.00), compared to CS subjects when DGF was not present.

Conclusions

Reduction of DGF rates for imported ECD kidneys is vital to optimize outcomes and increase their utilization. One strategy to decrease DGF rates may be to reduce static CS time during transportation, by utilizing a portable kidney perfusion machine.

Outcome Improvement for Hypothermic Machine Perfusion Versus Cold Storage for Kidneys From Cardiac Death Donors

Organ shortage has led to an increased use of kidneys from cardiac death donors (DCDs), but controversies about the methods of organ preservation still exist. This study aims to compare the effect of machine perfusion (MP) and cold storage (CS) in protecting kidneys harvested from DCDs. 141 kidney pairs from DCDs between July 2010 and July 2015 were included in this randomized controlled study. One kidney from each donor was randomly assigned to MP and the contralateral kidney was assigned to CS. Delayed graft function (DGF) rate, resistance index of renal arteries, early renal function, and survival rates were used to estimate the effect of preservation. The results showed that MP decreased the rate of DGF from 33.3 to 22.0% (P = 0.033). Ultrasound of the kidneys within 48 h after transplantation showed that the resistance index of renal main artery (0.673 ± 0.063 vs. 0.793 ± 0.124, P < 0.001), sub segmental artery (0.66 ± 0.062 vs. 0.764 ± 0.077, P < 0.001) and interlobular artery (0.648 ± 0.056 vs. 0.745 ± 0.111, P = 0.023) were all significantly lower in the MP group than those in the CS group. Furthermore, compared to the CS group, in the first 7 days following transplantation, the median urine volume was significantly higher (4080 mL vs. 3000 mL, P = 0.047) in kidneys sustained using MP and the median serum creatinine was remarkably lower (180 µmol/L vs. 390 µmol/L, P = 0.024). More importantly, MP group had higher 1- and 3-year graft survival rates (98% vs. 93%, P = 0.026; 93% vs. 82%, P = 0.036, respectively). Hypothermic MP improved the outcomes of DCD kidney transplantation.

Excellent outcomes in combined liver-kidney transplantation: Impact of kidney donor profile index and delayed kidney transplantation

The positive impact of delayed kidney transplantation (KT) on patient survival for combined liver-kidney transplantation (CLKT) has already been demonstrated by our group. The purpose of this study is to identify whether the quality of the kidneys (based on kidney donor profile index [KDPI]) or the delayed approach KT contributes to improved patient survival. In total, 130 CLKTs were performed between 2002 and 2015, 69 with simultaneous KT (group S) and 61 with delayed KT (group D) (performed as a second operation with a mean cold ischemia time [CIT] of 50 ± 15 hours). All patients were categorized according to the KDPI score: 1%-33%, 34%-66%, and 67%-99%. Recipient and donor characteristics were comparable within groups S and D. Transplant outcomes were comparable within groups S and D, including liver and kidney CIT, warm ischemia time, and delayed graft function. Lower KDPI kidneys (<34%) were associated with increased patient survival in both groups. The combination of delayed KT and KDPI 1%-33% resulted in 100% patient survival at 3 years. These results support that delayed KT in CLKT improves patient survival. The combination of delayed KT and low KDPI offers excellent patient survival up to 3 years. Improved outcomes in the delayed KT group including high KDPI kidneys supports expansion of the donor pool with the use of more extended criteria donor and donation after circulatory death kidneys. Liver Transplantation 24 222-232 2018 AASLD.

Machine Perfusion: Not Just for Marginal Kidney Donors

Interest in machine perfusion (MP) for donated kidneys has markedly increased in the past decade as a means to improve graft function, although the donor populations in which it should be applied have not yet been resolved. All adults undergoing de-novo isolated kidney transplantation from standard-criteria donors in the UNOS database 2005 to 2011 were reviewed with the primary endpoint of delayed graft function (DGF), defined as dialysis within seven days of transplantation, in those who received kidneys that underwent MP versus cold storage (CS) alone. Three methods were used to control for differences between groups. Multivariable logistic regression was performed, adjusting for donor and recipient characteristics significantly associated with DGF. Rates were also compared in a cohort of propensity-matched MP vs CS recipients. Finally, a paired-kidney study was performed, where one kidney underwent MP and the contralateral underwent CS. There were 36,323 patients, with unadjusted DGF rates of 18.6 per cent (n = 1830/9882) and 22.4 per cent (n = 5931/26,441; P < 0.001) in the MP vs CS groups, respectively. After multivariable analysis, the odds ratio for DGF in the MP group was 0.59 ( P < 0.001) versus CS. In the propensity-matched cohort, there were 8929 patients each in the MP and CS groups. DGF occurred in 16.8 per cent of the MP group vs 25.3 per cent with CS ( P < 0.001, OR 0.59). In the paired-kidney study, rates of DGF were 16.7 per cent vs 24.3 per cent ( P < 0.001) in the 1665 recipients each in the MP versus CS groups (OR 0.6). In conclusion, machine perfusion is beneficial in reducing DGF even when standard donors are utilized, and thus should not be limited to marginal kidneys.

Impact of duration of diabetes on outcome following pancreas transplantation

INTRODUCTION

The impact of duration of T1DM on outcomes following simultaneous pancreas and kidney transplantation (SPK), pancreas after kidney transplantation (PAK), and pancreas transplantation alone (PTA) is currently unknown.

MATERIALS AND METHODS

A total of 451 pancreas transplants performed at a single institution between January 2003 and April 2013 (SPK n = 238, PAK, n = 97, and PTA, n = 116) were divided into three groups based on cumulative years of T1DM (0-20 years, 21-30 years, and >30 years). Early (7-day) and late (90-day) pancreas allograft loss, patient and pancreas allograft survivals were analyzed.

RESULTS

While, PAK was more common in recipients with >30 years of T1DM (29%, p < 0.0047), PTA was more common in recipients with 0-20 years of T1DM (41%, p < 0.0011). In all transplant types, recipients age was significantly higher the longer the duration of diabetes. Although longer duration of T1DM correlated with a higher rate of major amputations in PAK recipients (p < 0.0032), no difference was observed in SPK or PTA. While early pancreas graft loss was 2-4% in SPK and PAK with shorter or longer T1DM (p = n.s.), it reached to 10% in PTA with T1DM > 30 years (p < 0.0097). Longer duration of T1DM affected late pancreas graft loss in PAK patients (8%, p < 0.0349). Patient and death-censored graft survival rates were similar in all types of pancreas transplantation extracted by accumulation of years of T1DM prior to transplant.

CONCLUSIONS

Longstanding T1DM does not seem to negatively impact recipient outcomes following all types of pancreas transplantation.

Metabolomic perfusate analysis during kidney machine perfusion: the pig provides an appropriate model for human studies

INTRODUCTION

Hypothermic machine perfusion offers great promise in kidney transplantation and experimental studies are needed to establish the optimal conditions for this to occur. Pig kidneys are considered to be a good model for this purpose and share many properties with human organs. However it is not established whether the metabolism of pig kidneys in such hypothermic hypoxic conditions is comparable to human organs.

METHODS

Standard criteria human (n = 12) and porcine (n = 10) kidneys underwent HMP using the LifePort Kidney Transporter 1.0 (Organ Recovery Systems) using KPS-1 solution. Perfusate was sampled at 45 minutes and 4 hours of perfusion and metabolomic analysis performed using 1-D 1H-NMR spectroscopy.

RESULTS

There was no inter-species difference in the number of metabolites identified. Of the 30 metabolites analysed, 16 (53.3%) were present in comparable concentrations in the pig and human kidney perfusates. The rate of change of concentration for 3-Hydroxybutyrate was greater for human kidneys (p<0.001). For the other 29 metabolites (96.7%), there was no difference in the rate of change of concentration between pig and human samples.

CONCLUSIONS

Whilst there are some differences between pig and human kidneys during HMP they appear to be metabolically similar and the pig seems to be a valid model for human studies.

To pump or not to pump: a comparison of machine perfusion vs cold storage for deceased donor kidney transplantation

BACKGROUND

A recent multicenter European trial has demonstrated reduced rates of delayed graft function when kidneys undergo machine perfusion before transplantation. This study was undertaken to evaluate the impact of machine perfusion on early kidney transplant function in the United States.

STUDY DESIGN

Retrospective review of United Network for Organ Sharing data from January 1, 2005 through March 31, 2011 was undertaken. Comparisons were made between kidneys that underwent machine perfusion (MP) vs cold storage (CS) alone in terms of delayed graft function (DGF). The analysis was performed in a cohort of MP and CS kidneys matched by propensity scoring, as well as in a cohort of paired kidneys from the same donor in which one underwent MP and the other underwent CS. Secondary end points analyzed included recipient length of stay after transplantation and graft survival.

RESULTS

In the overall cohort, rates of DGF were similar for MP and CS kidneys (25.7% vs 25.0%; p = 0.082), likely due to preferential use of MP in marginal kidneys. In the propensity matched cohort, MP was associated with significantly lower rates of DGF compared with CS (21.1% vs 29.1%; p < 0.001). These findings were corroborated by the paired kidney analysis, in which DGF occurred in 19.7% of the MP group compared with 27.5% of the CS group (p < 0.001). There was no difference in the hazard for graft failure between the MP and CS group in the propensity matched analysis (hazard ratio = 0.98; p = 0.622) and in the paired kidney analysis (hazard ratio = 1.02; p = 0.839).

CONCLUSIONS

Machine perfusion of deceased donor kidneys results in significantly decreased rates of DGF.

Impact of recipient age on whole organ pancreas transplantation

AIM

The goal of this study was to assess the impact of recipient age on post-transplant outcome.

METHODS

All pancreas transplants performed at Indiana University between 2003 and 2011 were reviewed. Demographic data were compared using standard chi-square and ANOVA testing. Standard Cox regression survival analysis was performed using a direct entry method for covariates.

RESULTS

Patients (n = 405) were divided by decade: <30 yr (n = 37), 30-39 (n = 109), 40-49 (n = 156), 50-59 (n = 85), and ≥ 60 yr of age (n = 18). Group demographics did not differ except for median ischemia time, which was between 7.0 and 8.5 h (p = 0.02). Early graft loss and one yr graft and patient survival were similar between the groups. Long-term patient survival demonstrated a trend toward decreased five-yr survival with increasing recipient age (p = NS). Graft survival at five yr by Cox regression was the lowest for the <30 yr group (74%), while all other groups were similar around 80% (p = NS).

CONCLUSION

No statistically significant differences in pancreas transplant outcomes were demonstrated when recipients were stratified by recipient age. These results suggest that older recipients can successfully undergo pancreas transplantation and expect five-yr outcomes similar to those seen in younger recipients.

Online oxygen measurements in ex vivo perfused muscle tissue in a porcine model using dynamic quenching methods

INTRODUCTION

Transplantation of autologous free tissue flaps is the best applicable technique for treating large and complex tissue defects and still has one major failure criterion. Tissue--and in particular muscle tissue--is strongly sensitive to ischemia, thus after a critical period of oxygen depletion the risk of a partial or total flap loss is high.

MATERIALS AND METHODS

For that reason a miniaturized ex vivo perfusion system has been developed, that supplies the tissue during operational delays. The purpose of this study was to determine the oxygenation levels during such a perfusion using different perfusates and therefore to objectify if a complementary oxygenation unit is required to improve perfusion quality. The oxygen levels of the tissue, as well of the perfusate, were measured by using minimal invasive optical oxygen sensors that are based on dynamic quenching. The ex vivo perfused tissue was the porcine rectus abdominis muscle.

RESULTS

Results show, that during perfusion with heparinized crystalloid fluid (Jonosteril) and heparinized autologous whole blood, additional oxygenation of the perfusion reactor led to different ex vivo oxygen tissue saturations, which can be detected by dynamic quenching.

CONCLUSION

Dynamic quenching methods are a promising and valuable technique to perform online oxygen measurements in ex vivo perfused muscle tissue in a porcine model.

Reduced expression of inflammatory genes in deceased donor kidneys undergoing pulsatile pump preservation

BACKGROUND

The use of expanded criteria donor kidneys (ECD) had been associated with worse outcomes. Whole gene expression of pre-implantation allograft biopsies from deceased donor kidneys (DDKs) was evaluated to compare the effect of pulsatile pump preservation (PPP) vs. cold storage preservation (CSP) on standard and ECD kidneys.

METHODOLOGY/PRINCIPAL FINDINGS

99 pre-implantation DDK biopsies were studied using gene expression with GeneChips. Kidneys transplant recipients were followed post transplantation for 35.8 months (range = 24-62). The PPP group included 60 biopsies (cold ischemia time (CIT) = 1,367+/-509 minutes) and the CSP group included 39 biopsies (CIT = 1,022+/-485 minutes) (P<0.001). Donor age (42.0±14.6 vs. 34.1±14.2 years, P = 0.009) and the percentage of ECD kidneys (PPP = 35% vs. CSP = 12.8%, P = 0.012) were significantly different between groups. A two-sample t-test was performed, and probe sets having a P<0.001 were considered significant. Probe set level linear models were fit using cold ischemia time and CSP/PPP as independent variables to determine significant probe sets (P<0.001) between groups after adjusting for cold ischemia time. Thus, 43 significant genes were identified (P<0.001). Over-expression of genes associated with inflammation (CD86, CD209, CLEC4, EGFR2, TFF3, among others) was observed in the CSP group. Cell-to-cell signaling and interaction, and antigen presentation were the most important pathways with genes significantly over-expressed in CSP kidneys. When the analysis was restricted to ECD kidneys, genes involved in inflammation were also differentially up-regulated in ECD kidneys undergoing CSP. However, graft survival at the end of the study was similar between groups (P = 0.2). Moreover, the incidence of delayed graft function was not significant between groups.

CONCLUSIONS/SIGNIFICANCE

Inflammation was the most important up-regulated pattern associated with pre-implantation biopsies undergoing CSP even when the PPP group has a larger number of ECD kidneys. No significant difference was observed in delayed graft function incidence and graft function post-transplantation. These findings support the use of PPP in ECD donor kidneys.

Protective effects of hypothermic ex vivo perfusion on ischemia/reperfusion injury and transplant outcomes

Hypothermic machine preservation (HMP) has been used in renal transplantation since the late 1960s with recent robust prospective, multicenter data showing lower rates of delayed graft function and improved graft survival. Although now clearly beneficial for renal transplantation, extrarenal machine perfusion has remained predominantly in preclinical investigations. Pancreatic HMP has drawn little clinical interest because HMP has been suggested to cause graft edema and congestion, which is associated with early venous thrombosis and graft failure. Early investigation showed no benefit of HMP in whole-organ pancreas transplant. One report did show that HMP increases islet cell yield after isolation. Preclinical work in liver HMP has been promising. Short- and long-term HMP has been shown to improve graft viability and reduce preservation injury, even in animal models of steatotic and donation after cardiac death. The first clinical study of liver HMP using a centrifugal dual perfusion technique showed excellent results with lower hepatocellular injury markers and no adverse perfusion-related outcomes. In addition, a dramatic attenuation of proinflammatory cytokine expression was observed. Further studies of liver HMP are planned with focus on developing a reproducible and standard protocol that will allow the widespread availability of this technology. Future research and clinical trials of novel organ preservation techniques, solutions, and interventions are likely to bring about developments that will allow further reduction of preservation-related ischemia/reperfusion injury and improved outcomes and allow safer utilization of the precious and limited resource of donor organs.

Hypothermic machine perfusion after static cold storage does not improve the preservation condition in an experimental porcine kidney model

Background

Combining hypothermic techniques, as a more practical approach to preservation, may enhance the condition of kidneys donated after cardiac death.

Methods

Porcine kidneys were retrieved after 10 min in situ warm ischaemia, then preserved by either 18 h static cold storage (CS), hypothermic machine perfusion for 18 h (HMP) or 14 h static CS followed by 4 h HMP (4HMP). Kidneys were reperfused for 3 h with oxygenated autologous blood on an isolated organ perfusion system to assess renal function and injury.

Results

Intrarenal resistance was significantly higher in the 4HMP group than in the CS and HMP groups: mean(s.d.) area under the curve (AUC) 8·48(2·97), 3·41(1·80) and 3·78(1·68) mmHg/min.h respectively (P = 0·011). Creatinine clearance was lower after 4HMP and CS: AUC 2·3(0·6) and 2·2(1·7) ml per min per 100g.h respectively versus 9·8(7·3) ml per min per 100g.h in the HMP group (P = 0·022). Levels of endothelin 1 were higher in the 4HMP and CS groups: mean(s.d.) 21·6(4·0) and 24·2(2·3) pg/ml respectively versus 11·4(4·6) pg/ml in the HMP group (P = 0·002). Morphological damage was increased in the 4HMP group.

Conclusion

This porcine kidney study demonstrated no advantage to the addition of 4 h of HMP after CS.

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

BACKGROUND

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

METHODS

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

RESULTS

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

A comparison of hypothermic machine perfusion versus static cold storage in an experimental model of renal ischemia reperfusion injury

INTRODUCTION

There is increasing support for the use of hypothermic machine perfusion (HMP) in an attempt to reduce preservation injury. However, experimental evidence is needed to further examine the effects of HMP on renal ischemia reperfusion injury.

METHODS

Porcine kidneys were subjected to 10 min of warm ischemia followed by 18 hr of static cold storage with hyperosomolar citrate (HOC), histidine-tryptophan-ketoglutarate (HTK), or University of Wisconsin (UW) solutions or 18 hr HMP with Kidney Perfusion Solution using the Lifeport perfusion system. Renal function, oxidative damage, and morphology were assessed during 3 hr of reperfusion with autologous blood using an isolated organ perfusion system.

RESULTS

During reperfusion, intrarenal resistance was significantly lower in the HMP group compared with HOC and UW (area under the curve; HMP 3.8+/-1.7, HOC 9.1+/-4.3, UW 7.7+/-2.2, HTK 5.6+/-1.9 mm Hg/min; P=0.006), and creatinine clearance was significantly higher compared with the UW group (area under the curve creatinine clearance; HMP 9.8+/-7.3, HOC 2.2+/-1.7, UW 1.8+/-1.0, HTK 2.1+/-1.8 mL/min/100 g; P=0.004). Tubular function was significantly improved in the HMP group (P<0.05); however, levels of lipid peroxidation were significantly higher (P=0.005).

CONCLUSION

HMP demonstrated a reduced level of preservation injury compared with the static techniques resulting in improved renal and tubular function and less tubular cell inflammation during reperfusion.

Machine perfusion or cold storage in organ transplantation: indication, mechanisms, and future perspectives

Most organs are currently preserved by cold storage (CS) prior to transplantation. However, as more so called marginal donor organs are utilized, machine perfusion has regained clinical interest. Recent studies have demonstrated advantages of pulsatile perfusion over CS preservation for kidney transplantation. However, it remains unclear whether there is a significant benefit of one preservation method over the other in general, or, whether the utilization of particular preservation approaches needs to be linked to organ characteristics. Proposed protective mechanisms of pulsatile perfusion remain largely obscure. It can be speculated that pulsatile perfusion may not only provide nutrition and facilitate the elimination of toxins but also trigger protective mechanisms leading to the amelioration of innate immune responses. Those aspects may be of particular relevance when utilizing grafts with suboptimal quality which may have an increased vulnerability to ischemia/reperfusion injury and compromised repair mechanisms. This review aims to enunciate the principles of organ perfusion and preservation as they relate to indication, aspects of organ protection and to highlight future developments.

Pulsatile perfusion of kidney allografts

PURPOSE OF REVIEW

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

RECENT FINDINGS

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

SUMMARY

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