Islet Isolation From Human Pancreas With Extended Cold Ischemia Time

The general consensus among transplant centers is that a cold ischemia time (CIT) beyond 8 hours results in reduced yields and quality of human islets. We sought to optimize the isolation process and enzymes for pancreata with extended CIT. We processed 16 extended CIT pancreata (13.2 ± 0.7 hours). Donors averaged 50.8 ± 2.6 (standard error of the mean) years old with a body mass index of 28.6 ± 1.5. Glands were shipped in cold organ preservation solution without oxygenated perfluorocarbon. Isolations were performed under a protocol optimized for digestion with the new cGMP collagenase from Roche. Purification used continuous Euroficoll/University of Wisconsin gradients. Islets were cultured in two types of Prodo cGMP islet culture media and/or in Miami 1A media. Glucose-stimulated insulin secretion assays were performed after 8 to 16 days of culture. Prepurification yield averaged 415 ± 41 KIEQ postpurification, 359 ± 29 KIEQ (purification loss 13.5%); and postculture 317 ± 27 KIEQ (culture loss 11.7%). Our process liberated an average of 4278 IEQ/g of pancreas (97 ± 5 g). Most islets were recovered in the purest fraction (purity 79.7% ± 1.9%). Culture loss in our enhanced culture media was 11.7%. After 2 to 3 days in culture, viability was 92% ± 1%. Islets exhibited compactness and dithizone staining. Glucose-stimulated insulin secretion assays performed after 3 to 23 days in our PIM(R) media resulted in a stimulation index of 6.8 ± 1.7 (G50 to G350). We concluded that our human islet isolation process permitted the recovery of large numbers of high-quality human islets from extended CIT pancreata and that our cGMP islet culture media was superior to the current standard CMRL-based media.     

Pulsatile pump perfusion of pancreata before human islet cell isolation

Machine pulsatile perfusion for whole pancreas preservation might improve yield, viability, and function of human islets recovered after prolonged cold ischemia times. Four human pancreata were procured from cadaver donors (1 non-heart-beating donor) and stored in cold University of Wisconsin (UW) solution for a mean 13 hours prior to placement on a machine pulsatile perfusion device. The four pancreata were perfused for 4 hours with UW solution before undergoing islet isolation. Islets were quantified, viability was assessed, and insulin secretion was measured. Results were compared with nonpumped islet isolations stratified for cold ischemia time (CIT) <8 hours or cold ischemia time >8 hours. The islet yield for the four pumped pancreata was 3435 (+/-1951) islet equivalents/gram pancreas tissue (IEQ/g), compared with a mean yield of 5134 (+/-2700) IEQ/g and 2640 (+/-1000) IEQ/g from pancreas with <8 hours and >8 hours CIT, respectively. The mean viability after machine pulsatile perfusion was 86% (vs 74% and 74% for the <8 hour and >8 hour CIT groups). The mean viable yield (total yield x viability) was 2937 IEQ/g for machine perfusion, compared with 3799 IEQ/g and 1937 IEQ/g from pancreata with <8 hours and >8 hours CIT, respectively. The insulin secretion index of islets after machine perfusion was 6.4, compared with indices of 1.9 and 1.8 for the <8 hour and >8 hour CIT groups. This preliminary data indicates that low-flow machine pulsatile perfusion of pancreata with prolonged cold ischemia time can result in excellent yield, viability, and function.     

Impact of ischemia time on islet isolation success and posttransplantation outcomes: A retrospective study of 452 pancreas isolations

Many variables impact islet isolation, including pancreas ischemia time. The ischemia time upper limit that should be respected to avoid a negative impact on the isolation outcome is not well defined. We have performed a retrospective analysis of all islet isolations in our center between 2008 and 2018. Total ischemia time, cold ischemia time, and organ removal time were analyzed. Isolation success was defined as an islet yield ≥200 000 IEQ. Of the 452 pancreases included, 288 (64%) were successfully isolated. Probability of isolation success showed a significant decrease after 8 hours of total ischemia time, 7 hours of cold ischemia time, and 80 minutes of organ removal time. Although we observed an impact of ischemia time on islet yield, a probability of isolation success of 50% was still present even when total ischemia time exceeds 12 hours. Posttransplantation clinical outcomes were assessed in 32 recipients and no significant difference was found regardless of ischemia time. These data indicate that although shorter ischemia times are associated with better islet isolation outcomes, total ischemia time >12 hours can provide excellent results in appropriately selected donors.     

Rewarming Preservation by Organ Perfusion System for Donation After Cardiac Death Liver Grafts in Pigs

Background

Use of grafts from donors after cardiac death (DCD) would greatly contribute to the expansion of the donor organ pool. However, this requires the development of novel preservation methods to recover the organ from changes due to warm ischemia time (WIT).

Methods

Porcine livers were perfused with a newly developed machine perfusion (MP) system. The livers were perfused with modified University of Wisconsin solution (UW) − gluconate. All grafts were procured after acute hemorrhagic shock with the ventilator off. For group 1 (n = 6), grafts were procured after WIT of 60 minutes and preserved by hypothermic MP (HMP) for 3 hours. For group 2 (n = 5), grafts were preserved with 2 hours of simple cold storage (SCS) and HMP for 2 hours. For group 3 (n = 6), grafts were preserved with 2 hours of SCS and rewarming up to 25°C by MP for 2 hours (RMP). The preserved liver grafts were transplanted orthotopically.

Results

The alanine aminotransferase level in perfusate in RMP during perfusion preservation was maintained at less than that of HMP. The levels of aspartate aminotransferase and lactate dehydrogenase in the 2 hours after reperfusion were significantly lower in group 3. Histologically, the necrosis of hepatocytes was less severe in group 3. The survival rate in group 3 was 2/4, but 0/4 in the other group.

Conclusion

RMP is expected to facilitate the recovery of the DCD liver grafts.     

Pancreas preservation fluid microbial contamination is associated with poor islet isolation outcomes – a multi‐centre cohort study

The microbiological safety of islet preparations is paramount. Preservation medium contamination is frequent, and its impact on islet yield and function remains unclear. Microbiological samples collected during islet isolations from 2006 to 2016 were analyzed and correlated to isolation and allo‐ and autotransplantation outcomes. Microbial contamination of preservation medium was found in 64.4% of processed donor pancreases (291/452). We identified 464 microorganisms including Staphylococcus (253/464, 54.5%), Streptococcus (31/464, 6.7%), and Candida species (25/464, 5.4%). Microbial contamination was associated with longer warm and cold ischemia times and lower numbers of postpurification islet equivalents, purity, transplant rate, and stimulation index (all P < 0.05). Six percent of the preparations accepted for transplantation showed microbial contamination after isolation (12/200); 9 of 12 were Candida species. Six patients were transplanted with a sample with late microbial growth discovered after the infusion. Insulin independence rate was not affected. This risk of transplanting a contaminated islets preparation was reduced by half following the implementation of an additional sampling after 24 h of islet culture. Pancreas preservation fluid microbial contamination is associated with lower transplant rate and poorer in vitro function, but not with changes in graft survival. Culture medium testing 1 day after isolation reduces the risk of incidental transplantation with contaminated islets.     

Clinical use of donation after circulatory death pancreas for islet transplantation

Due to a shortage of donation after brain death (DBD) organs, donation after circulatory death (DCD) is increasingly performed. In the field of islet transplantation, there is uncertainty regarding the suitability of DCD pancreas in terms of islet yield and function after islet isolation. The aim of this study was to investigate the potential use of DCD pancreas for islet transplantation. Islet isolation procedures from 126 category 3 DCD and 258 DBD pancreas were performed in a 9-year period. Islet yield after isolation was significantly lower for DCD compared to DBD pancreas (395 515 islet equivalents [IEQ] and 480 017 IEQ, respectively; p = .003). The decrease in IEQ during 2 days of culture was not different between the two groups. Warm ischemia time was not related to DCD islet yield. In vitro insulin secretion after a glucose challenge was similar between DCD and DBD islets. After islet transplantation, DCD islet graft recipients had similar graft function (AUC C-peptide) during mixed meal tolerance tests and Igls score compared to DBD graft recipients. In conclusion, DCD islets can be considered for clinical islet transplantation.     

Use of Ex Vivo Normothermic Perfusion for Quality Assessment of Discarded Human Donor Pancreases

A significant number of pancreases procured for transplantation are deemed unsuitable due to concerns about graft quality and the associated risk of complications. However, this decision is subjective and some declined grafts may be suitable for transplantation. Ex vivo normothermic perfusion (EVNP) prior to transplantation may allow a more objective assessment of graft quality and reduce discard rates. We report ex vivo normothermic perfusion of human pancreases procured but declined for transplantation, with ABO‐compatible warm oxygenated packed red blood cells for 1–2 h. Five declined human pancreases were assessed using this technique after a median cold ischemia time of 13 h 19 min. One pancreas, with cold ischemia over 30 h, did not appear viable and was excluded. In the remaining pancreases, blood flow and pH were maintained throughout perfusion. Insulin secretion was observed in all four pancreases, but was lowest in an older donation after cardiac death pancreas. Amylase levels were highest in a gland with significant fat infiltration. This is the first study to assess the perfusion, injury, as measured by amylase, and exocrine function of human pancreases using EVNP and demonstrates the feasibility of the approach, although further refinements are required.     

Impact of Hypothermic Preservation on Tissue Yield and Viability in Pig Pancreata

Introduction

Chronic shortage of quality human cadaveric pancreata limits islet transplantation. Porcine islet xenotransplantation is being explored to increase the donor pool. For clinical-ready islets, centralized animal husbandry, Current Good Manufacturing Practice–regulated processing facilities, and organ transportation support are required. Amount of cold ischemia time (CIT) before isolation significantly affects transplantation. The goal of this study was to determine the maximum safe CIT of whole pancreata before islet isolation.

Materials and Methods

Pancreata were rapidly removed from Yorkshire pigs (age, 14–22 days) and stored in modified University of Wisconsin solution or in EuroCollins solution at 4^°C. Pancreata were processed with <1 hour CIT (control) or stored for 4 or 12 hours before isolation. Islet yield and percent purity and viability were determined after 7 days of in vitro tissue culture and maturation. Samples from nonprocessed pancreata were collected and snap-frozen in liquid nitrogen at 0, 3, 6, 9, 12, 15, and 24 hours of preservation, then analyzed for adenosine diphosphate/adenosine triphosphate ratio as a measure of tissue energetics.

Results

Up to 12 hours in cold storage had no significant impact on overall islet yield after 7 days of in vitro culture compared with controls; islet yield at the end of the maturation process was 28,700 ± 500 islet equivalents per pancreas (mean ± SEM control yield, 30,300 ± 900 islet equivalents per pancreas); islet purity was 75 ± 5% compared with 74 ± 5% in controls. Islet viability was significantly reduced at 12 hours compared with controls (80 ± 6% vs 96 ± 5%; P < .05). The tissue adenosine diphosphate/adenosine triphosphate ratio was maintained within the first 6 hours (1.6 ± 0.1 to 1.8 ± 0.2; P = NS) but was markedly increased during the 24-hour study (3.3 ± 0.1 at 24 hours), indicating a progressive loss of adenosine triphosphate tissue stores.

Conclusions

Young pig pancreata can be hypothermically stored for up to 12 hours without affecting islet yield and purity; however, islet viability is reduced. These data highlight the need for uniform shipping parameters to standardize islet quality, ideally with CIT <6 hours.     

Outcomes of donation after circulatory death kidneys undergoing hypothermic machine perfusion following static cold storage: A UK population‐based cohort study

Evidence is currently lacking regarding the outcomes of kidneys undergoing hypothermic machine perfusion (HMP) in patients in the United Kingdom. Using the National Health Service Blood and Transplant database, the authors compared outcomes for recipients of single‐organ donation after circulatory death (DCD) kidneys preserved with HMP with those preserved using only static cold storage (SCS). Between 2007 and 2015, HMP was used in 19.1% (864/4,529) of kidneys. Rates of delayed graft function (DGF) were significantly lower in organs preserved with HMP than for organs preserved with SCS (34.2% vs 42.0%, P < .001), despite a slightly longer cold ischemic time (median: 14.8 vs 14.1 hours, P < .001). Multivariable analysis found the effect of preservation modality to remain significant, with HMP organs having a significantly lower rate of DGF (odds ratio 0.65, 95% confidence interval 0.53‐0.80, P < .001) and significantly shorter times to DGF resolution (average: 6.1 vs 7.4 days, P = .003) than SCS organs. The patient (P = .313) and graft (P = .263) survival rates were similar in the 2 preservation groups. HMP was associated with a marginal functional benefit in 1‐year creatinine values (P = .044), with adjusted averages of 1.36 mg/dL (HMP) versus 1.40 mg/dL (SCS). This study supports the use of HMP and aids decision‐making over its instigation, which may improve short‐term patient outcomes.     

Clinical islet isolation and transplantation outcomes with deceased cardiac death donors are similar to neurological determination of death donors

In islet transplantation, deceased cardiac death (DCD) donation has been identified as a potential extended source. There are currently no studies comparing outcomes between these categories, and our goal was to compare islet isolation success rates and transplantation outcomes between DCD and neurological determination of death (NDD) donors. Islet isolations from 15 DCD and 418 NDD were performed in our centre between September 2008 and September 2014. Donor variables, islet yields, metabolic function of isolated isled and insulin requirements at 1‐month post‐transplant were compared. Compared to NDD, pancreata from DCD were more often procured locally and donors required less vasopressive support (P < 0.001 and P = 0.023, respectively), but the other variables were similar between groups. Pre‐ and postpurification islet yields were similar between NDD and DCD (576 vs. 608 × 10³ islet equivalent, P = 0.628 and 386 vs. 379, P = 0.881, respectively). The metabolic function was similar between NDD and DCD, as well as the mean decrease in insulin requirement at 1‐month post‐transplantation (NDD: 64.82%; DCD: 60.17% reduction, P = 0.517). These results support the broader use of DCD pancreata for islet isolation. A much larger DCD islet experience will be required to truly determine noninferiority of both short‐ and long‐term outcomes.     

Effects of remote ischaemic preconditioning on intraportal islet transplantation in a rat model

Remote ischaemic preconditioning (RIPC), which is the intermittent interruption of blood flow to a site distant from the target organ, is known to improve solid organ resistance to ischaemia‐reperfusion injury. This procedure could be of interest in islet transplantation to mitigate hypoxia‐related loss of islet mass after isolation and transplantation. Islets isolated from control or RIPC donors were analyzed for yield, metabolic activity, gene expression and high mobility group box‐1 (HMGB1) content. Syngeneic marginal mass transplantation was performed in four streptozotocin‐induced diabetic groups: control, RIPC in donor only, RIPC in recipient only, and RIPC in donor and recipient. Islets isolated from RIPC donors had an increased yield of 20% after 24 h of culture compared to control donors (P = 0.007), linked to less cell death (P = 0.08), decreased expression of hypoxia‐related genes (Hif1a P = 0.04; IRP94 P = 0.008), and increased intra‐cellular (P = 0.04) and nuclear HMGB1. The use of RIPC in recipients only did not allow for reversal of diabetes, with increased serum HMGB1 at day 1; the three other groups demonstrated significantly better outcomes. Performing RIPC in the donors increases islet yield and resistance to hypoxia. Validation is needed, but this strategy could help to decrease the number of donors per islet recipient.     

Impact of warm ischemia time on outcomes for kidneys donated after cardiac death Post-KAS

Prolonged warm (WIT) and cold (CIT) ischemia times are often important considerations in the discard of DCD kidneys, but their impact on post-transplant outcomes in the post-KAS era is unclear. We examined the association of ischemia time on delayed graft function (DGF) and death-censored graft failure for DCD kidneys. The 2018 SRTR SAF was utilized to identify post-KAS DCD kidney transplants occurring from 2015 to 2018. Relative risk and Cox regression were used to calculate risk of delayed graft function and hazard of death-censored graft failure, respectively. We identified 4,680 kidneys from DCD donors transplanted from 2015 to 2018 with recorded WIT and CIT times. Median WIT was 21.0 minutes (IQR 14.0-28.0), and CIT was 18.5 hours (IQR 13.9-23.5). The overall incidence of DGF was 42.7%. In a univariable relative risk regression model, extended CIT (24-30 hours:RR 1.37, 95% CI 1.15-1.77; >30 hours:RR 1.47, 95% CI 1.22-1.77) and WIT (20-40 minutes:RR 1.10, 95% CI 1.03-1.17) were associated with increased risk of DGF. When included in a multivariable model, neither prolonged CIT nor WIT were significantly associated with death-censored graft failure. Prolonged WIT and CIT are associated with increased DGF but not death-censored graft failure in recipients of DCD kidney transplants in the post-KAS era. Extended ischemia alone should not be used as a basis for discard or non-utilization of these organs.     

Portal Venous Oxygen Persufflation of the Donation after Cardiac Death pancreas in a rat model is superior to static cold storage and hypothermic machine perfusion

Success of clinical pancreatic islet transplantation depends on the mass of viable islets transplanted and the proportion of transplanted islets that survive early ischaemia reperfusion injury. Novel pancreas preservation techniques to improve islet preservation and viability can increase the utilization of donation after cardiac death donor pancreases for islet transplantation. Rat pancreases were retrieved after 30 min of warm ischaemia and preserved by static cold storage, hypothermic machine perfusion or retrograde portal venous oxygen persufflation for 6 h. They underwent collagenase digestion and density gradient separation to isolate islets. The yield, viability, morphology were compared. In vitro function of isolated islets was compared using glucose stimulated insulin secretion test. Portal venous oxygen persufflation improved the islet yield, viability and morphology as compared to static cold storage. The percentage of pancreases with good in vitro function (stimulation index > 1.0) was also higher after oxygen persufflation as compared to static cold storage. Retrograde portal venous oxygen persufflation of donation after cardiac death donor rat pancreases has the potential to improve islet yield.     

Kidney transplantation after oxygenated machine perfusion preservation with Custodiol‐N solution

Custodiol‐N, a new preservation solution, has been shown particularly suitable for hypothermic machine perfusion preservation (HMP) in isolated porcine kidneys. These preliminary results should be confirmed in an actual transplant model in vivo. Kidney function after 21 h of HMP was studied in an autotransplant model using Landrace pigs (25–30 kg; n = 6 per group). Perfusion was performed with oxygenated perfusate, using either Custodiol‐N solution including 50 g/l dextran 40 (CND) or kidney perfusion solution 1 (KPS‐1) as gold standard. Viability of the grafts was followed for 1 week after bilateral nephrectomy in the recipient pigs. HMP with CND resulted in less acute tubular injury, evaluated by levels of fatty acid‐binding protein and better clearance function during the first 24 h after Tx than with KPS‐1 (P < 0.05, resp.). Serum creatinine tended to be lower in the CND group during the whole observation period. Histological tissue scores one week after Tx were similar in both groups. Expression of endothelin‐1 as well as of Toll‐like receptor 4 15 min after reperfusion was lower in the CND group (P < 0.05), suggesting less endothelial stress response. The data provide first in vivo evidence for the suitability of Custodiol‐N as an effective perfusate for renal machine perfusion.     

Continuous Normothermic Ex Vivo Kidney Perfusion Is Superior to Brief Normothermic Perfusion Following Static Cold Storage in Donation After Circulatory Death Pig Kidney Transplantation

Hypothermic preservation is known to cause renal graft injury, especially in donation after circulatory death (DCD) kidney transplantation. We investigated the impact of cold storage (SCS) versus short periods of normothermic ex vivo kidney perfusion (NEVKP) after SCS versus prolonged, continuous NEVKP with near avoidance of SCS on kidney function after transplantation. Following 30 min of warm ischemia, kidneys were removed from 30‐kg Yorkshire pigs and preserved for 16 h with (A) 16 h SCS, (B) 15 h SCS + 1 h NEVKP, (C) 8 h SCS + 8 h NEVKP, and (D) 16 h NEVKP. After contralateral kidney resection, grafts were autotransplanted and pigs followed up for 8 days. Perfusate injury markers such as aspartate aminotransferase and lactate dehydrogenase remained low; lactate decreased significantly until end of perfusion in groups C and D (p < 0.001 and p = 0.002). Grafts in group D demonstrated significantly lower serum creatinine peak when compared to all other groups (p < 0.001) and 24‐h creatinine clearance at day 3 after surgery was significantly higher (63.4 ± 19.0 mL/min) versus all other groups (p < 0.001). Histological assessment on day 8 demonstrated fewer apoptotic cells in group D (p = 0.008). In conclusion, prolonged, continuous NEVKP provides superior short‐term outcomes following DCD kidney transplantation versus SCS or short additional NEVKP following SCS.     

Time of Cold Storage Prior to Start of Hypothermic Machine Perfusion and Its Influence on Graft Survival

BackgroundHypothermic machine perfusion (HMP) has become a standard method of preservation for kidneys procured from expanded-criteria donors and donors after cardiac death. There are different systems and approaches to the HMP preservation period, with cold storage prior to HMP sometimes taking several hours. This study evaluated whether the time at which kidneys receive HMP had any influence on the outcomes of kidney transplantation.MethodsIn this analysis, patient and graft survival were evaluated over a 1-year post-transplantation period. Patients who received HMP kidneys (n = 379) were divided into 2 groups: those who received kidneys with a cold ischemia time (CIT) prior to HMP <295 minutes (group G1; n = 254) and those who received kidneys with CIT prior to HMP >295 minutes (group G2; n = 125).ResultsDelayed graft function was observed in 31.8% (81/254) of patients in group G1 vs 46.4% (58/125) of patients in group G2 (P = .007). One-year graft survival was statistically higher in the group G1 (93.2%; 233/254) vs group G2 (86.5%; 105/125, P = .029). Mean 1-year estimated glomerular filtration rate was significantly better in the group G1.ConclusionsIn conclusion, introduction of HMP up to 295 minutes from procurement led to better early and 1-year graft results. Kidneys should receive HMP as soon as possible after retrieval, preferably during procurement.     

No beneficial effect of two-layer storage compared with UW-storage on human islet isolation and transplantation

BACKGROUND: Shipment of pancreata between distant centers is frequently associated with prolonged cold ischemia time (CIT) that leads to poorer outcomes for islet transplantation. Clinical pilot trials have indicated that oxygenation of explanted human pancreata utilizing the two-layer method (TLM) allows the use of marginal donor pancreata for islet transplantation. The present study aimed to clarify whether TLM enhances the ischemic tolerance of human pancreata. METHODS: We analyzed retrospectively the outcome of 200 human islet isolations performed after TLM preservation or storage in University of Wisconsin solution (UWS). RESULTS: Donor characteristics and digestion parameters did not vary significantly between TLM-preserved and UWS-stored pancreata. No differences were observed between experimental groups with regard to islet yield, purity, or dynamic glucose stimulation index after either short or prolonged CIT. However, CIT and stimulation index were negatively correlated in each experimental group. The isolation outcome in donors aged > or =60 years was not increased after TLM preservation when compared to UWS storage. No effect was observed regarding islet posttransplant function in recipients with established kidney grafts. CONCLUSIONS: The present study suggests that the ischemic tolerance of human pancreata cannot be extended by TLM preservation. In addition, TLM does not seem to improve the isolation outcome for pancreata from elderly donors.     

Influence of prolonged cold ischemia in renal transplantation

van der Vliet JA, Warlé MC, Cheung CLS, Teerenstra S, Hoitsma AJ. Influence of prolonged cold ischemia in renal transplantation.
Clin Transplant 2011: 25: E612–E616. © 2011 John Wiley & Sons A/S. Abstract: Aim: To determine to what extent current cold ischemia times (CITs) affect the results of renal transplantation in the Netherlands. Methods: Retrospective survey of the Dutch Organ Transplant Registry concerning transplants from deceased donors between 1990 and 2007. Results: A total of 6322 recipients were identified, of whom 5306 received a kidney from deceased heartbeating (HBD) and 1016 from donors after cardiac death (DCD). Mean CIT was 24.0 ± 7.9 h in HBD and 21.6 ± 6.7 h in DCD. The percentage delayed graft function (DGF) was 12.3 and 50.4, respectively (p < 0.001). Primary non‐function (PNF) occurred in, respectively, 1.7% and 5.0% (p < 0.001). Serum creatinine after three months was 166 μM in HBD and 213 μM in DCD (p < 0.001). Five‐yr graft survival was 79.5% and 78.3%, respectively (p = ns). In multivariate analysis, CIT proved to be an independent risk factor for DGF and PNF. Shorter CIT was associated with better graft survival in both groups with a hazard ratio of 1.024 (1.011–1.037, 95% CI)/h. CIT <20 h was associated with a graft survival benefit of 3% after five yr in HBD and CIT of <16 h with a benefit of 10% in DCD. Conclusions: Longer CITs are associated with the occurrence of DGF, PNF and decreased graft survival in the Netherlands.     

The effect on early renal function of various dynamic preservation strategies in a preclinical pig ischemia–reperfusion autotransplant model

The aims of this study were to determine the most optimal timing to start machine perfusion during kidney preservation to improve early graft function and to evaluate the impact of temperature and oxygen supply during machine perfusion in a porcine ischemia–reperfusion autotransplant model. The left kidney of an approximately 40‐kg female Belgian Landrace pig was exposed to 30 minutes of warm ischemia via vascular clamping and randomized to 1 of 6 study groups: (1) 22‐hour static cold storage (SCS) (n = 6), (2) 22‐hour hypothermic machine perfusion (HMP) (n = 6), (3) 22‐hour oxygenated HMP (n = 7), (4) 20‐hour HMP plus 2‐hour normothermic perfusion (NP) (n = 6), (5) 20‐hour SCS plus 2‐hour oxygenated HMP (n = 7), and (6) 20‐hour SCS plus 2‐hour NP (n = 6). Graft recovery measured by serum creatinine level was significantly faster for continuous HMP preservation strategies compared with SCS alone and for all end‐ischemic strategies. The active oxygenated 22‐hour HMP group demonstrated a significantly faster recovery from early graft function compared with the 22‐hour nonactive oxygenated HMP group. Active oxygenation was also found to be an important modulator of a faster increase in renal flow during HMP preservation. Continuous oxygenated HMP applied from the time of kidney procurement until transplant might be the best preservation strategy to improve early graft function.     

Twenty-four hour hypothermic machine perfusion preservation of porcine pancreas facilitates processing for islet isolation

Procurement of donor pancreata for islet isolation and transplantation is not yet widely practiced due to concerns about the impact of postmortem ischemia on functional islet yields. Perfusion/preservation technology may help to circumvent ischemic injury as applied in this study of porcine pancreata prior to islet isolation. Pancreata harvested from adult pigs were assigned to 1 of 3 preservation treatment groups: G1, fresh controls, processed immediately with minimum cold ischemia (<1 hour); G2, static cold storage, flushed with cold UW-Viaspan and stored at 2 degrees -4 degrees C for 24 hours; and G3, hypothermic machine perfusion (HMP) on a pulsatile LifePort machine Organ Recovery Systems, Inc., Des Plaines, Ill, United States with KPS1 solution at 4-7 degrees C and low pressure (10 mm Hg) for 24 hours. Islet isolation was then accomplished using conventional methods. Product release criteria were used to assess islet yield and function. Islet yield was markedly different between the treatment groups. There was a statistically significant increased yield in the HMP group over static cold storage in UW-Viaspan (P < .05). Functionally, the islets from each experimental group were equivalent and not significantly different from fresh controls (G1). Dithizone staining of islets showed consistently more uniform digestion of pancreata from G3 compared with G1 and G2, with greater separation of the tissue and fewer entrapped islets. HMP for 24 hours was well tolerated, leading to moderate edema but no loss of function of the harvested islets. The edema appeared to aid in enzymatic digestion, producing a greater yield and purity of islets compared with pancreata subjected to 24 hours of static cold storage.