Initial experience using histidine-tryptophan-ketoglutarate solution in clinical pancreas transplantation

Exploring definitions of graft pancreatitis following pancreas transplantation: A scoping review

Despite the clinical relevance of graft pancreatitis (GP) after pancreas transplantation (PT), a universally accepted definition is lacking. Aim of this scoping review was to provide a systematic overview of GP definitions reported in the literature. MEDLINE, Web of Science and Embase were searched for relevant articles. Prospective/retrospective studies reporting a GP definition were included. The included series (n = 20) used four main criteria (clinical, biochemical, radiological and pathological) to define GP. Overall, 9 studies defined GP using a single criterion (n = 8 biochemical, n = 1 pathological), 7 series using two criteria (n = 3 clinical + biochemical, n = 3 biochemical + radiological, n = 1 clinical + radiological), 3 series using three criteria (n = 3 clinical + biochemical + radiological), and 1 series using four criteria. Overall, 20 definitions of GP were found. GP rate was reported by 19 series and ranged between 0% and 87%. This scoping review confirms that a universally accepted definition of GP is absent, and there is no consensus on the criteria on which it should be grounded. Future research should focus on developing a validated definition of GP.

Deceased Donor Flush Volume Similar for Histidine-Tryptophan-Ketoglutarate and University of Wisconsin at a Single US Organ Procurement Organization: Adult and Pediatric Data

BACKGROUND

Histidine-tryptophan-ketoglutarate (HTK) and University of Wisconsin (UW) solutions are the two primary solid-organ preservation solutions used in the United States (>95%), but flush volumes vary markedly by region and center. This study analyzes data from a single organ procurement organization (OPO) to determine the actual clinical flush volumes used for HTK and UW for liver and pancreas grafts.

METHODS

All procurements at Indiana Donor Network were analyzed (2016-2020), and data were extracted from the on-site records. Variables included procuring center, solution, volumes, and vessels flushed. Brand and generic versions were considered equivalent. No clinical transplant outcomes were available.

RESULTS

Data were analyzed from 875 liver and 192 pancreas procurements by over 70 U.S. centers representing 10 of 11 UNOS regions. The large majority of liver grafts were preserved with HTK (n=810, 93%; UW n=93, 7%). All liver donors received an aortic flush (100%), while portal vein flush was 14% in-situ and 88% back table. For liver grafts, the median volume of infused solution was less for HTK when compared to UW (4225mL vs 5500mL, p=0.04). For pancreas procurement, 100% received aortic flush of the graft, with median HTK and UW volumes being equivalent (3000mL; p=0.85). Pediatric organs were flushed with markedly higher weight-based volumes.

CONCLUSIONS

Flush volumes for HTK and UW are similar at one midwestern OPO, with data comprised of procurements performed by centers from across the U.S. These data demonstrate that low-volume HTK flush is commonly used, and this practice may be considered as a cost-saving measure.

Current Trends in Organ Preservation Solutions for Pancreas Transplantation: A Single-Center Retrospective Study

Due to the high vulnerability of the pancreas to ischemia-reperfusion injury, choices regarding preservation solution markedly affect pancreas transplant success. A retrospective single-center analysis of 380 pancreas transplants (2000-2019) was performed to correlate current preservation solutions with transplant outcomes. Early graft failure requiring transplantectomy within 30 days post-transplant occurred in 7.5% for University of Wisconsin (UW) group (n = 267), 10.8% of Celsior (CS) group (n = 83), 28.5% of Histidine-Tryptophan-Ketoglutarate (HTK) group (n = 7), and none for Institut Georges Lopez-1 (IGL-1) group (n = 23). The most common causes of technical failures in this cohort included abdominal hemorrhage (8.4%); graft pancreatitis (3.7%); fluid collections (2.6%); intestinal complications (6.6%); and vascular thrombosis (20.5%). Although IGL-1 solution provided lower surgical complication rates, no significant differences were found between studied groups. Nevertheless, HTK solution was associated with elevated pancreatitis rates. The best graft survival was achieved at 1 year using UW and IGL-1, and at 3 and 5 years using IGL-1 (p = 0.017). There were no significant differences in patient survival after a median follow-up of 118.4 months. In this setting therefore, IGL-1 solution appears promising for perfusion and organ preservation in clinical pancreas transplantation, compared to other commonly used solutions.

Adhesion Characteristics of Human Pancreatic Islets, Duct Epithelial Cells, and Acinar Cells to a Polymer Scaffold

We reported in 2018 that among several extracellular matrices, fibronectin, type I collagen, type IV collagen, laminin I, fibrinogen, and bovine serum albumin, fibronectin is particularly useful for adhesion of porcine pancreatic tissue. Subsequently, we developed a technology that enables the chemical coating of the constituent motifs of fibronectin onto cell culture dishes. In this experiment, we used islets (purity ≥ 90%), duct epithelial cells (purity ≥ 60%), and acinar cells (purity ≥ 99%) isolated from human pancreas according to the Edmonton protocol published in 2000 and achieved adhesion to the constituent motifs of fibronectin. A solution including cGMP Prodo Islet Media was used as the assay solution. In islets, adhesion was enhanced with the constitutive motifs of fibronectin compared with uncoated islets. In the functional evaluation of islets, insulin mRNA expression and insulin secretion were enhanced by the constitutive motif of fibronectin compared with non-coated islets. The stimulation index was comparable between non-coated islets and fibronectin motifs. In duct epithelial cells, adhesion was mildly promoted by the fibronectin component compared with non-coated component, while in acinar cells, adhesion was inhibited by the fibronectin component compared with the non-coated component. These data suggest that the constitutive motifs of fibronectin are useful for the adhesion of islets and duct epithelial cells.

Preservation of pancreas in the University of Wisconsin solution supplemented with AP39 reduces reactive oxygen species production and improves islet graft function

Ischemia-reperfusion injury (IRI) results in increased rates of delayed graft function and early graft loss. It has recently been reported that hydrogen sulfide (H₂ S) protects organ grafts against prolonged IRI. Here, we investigated whether the preservation of pancreas in University of Wisconsin (UW) solution supplemented with AP39, which is a mitochondrial-targeted H₂ S donor, protected pancreatic islets against IRI and improved islet function. Porcine pancreata were preserved in the UW solution with AP39 (UW + AP39) or the vehicle (UW) for 18 h, followed by islet isolation. The islet yields before and after purification were significantly higher in the UW + AP39 group than in the UW group. The islets isolated from the pancreas preserved in UW + AP39 exhibited significantly decreased levels of reactive oxygen species (ROS) production and a significantly increased mitochondrial membrane potential as compared to the islets isolated from the pancreas preserved in the vehicle. We found that the pancreas preserved in UW + AP39 improved the outcome of islet transplantation in streptozotocin-induced diabetic mice. These results suggest that the preservation of pancreas in UW + AP39 protects the islet grafts against IRI and could thus serve as a novel clinical strategy for improving islet transplantation outcomes.

Impact of Histidine-Tryptophan-Ketoglutarate Versus University of Wisconsin Solution on the Outcome of Pancreas Transplant With Cold Ischemic Time ≥12 Hours: A Retrospective Study

OBJECTIVES

Histidine-tryptophan-ketoglutarate and University of Wisconsin solutions are currently used for pancreas graft preservation. Our hypothesis was whether the use of histidine-tryptophan-ketoglutarate solution is associated with worse pancreas graft survival than University of Wisconsin solution, in general and after prolonged cold ischemic time of ≥12 hours.

MATERIALS AND METHODS

This retrospective study investigated the impact of static cold storage in histidine-tryptophan-ketoglutarate (n = 133) versus University of Wisconsin (n = 107) solution on outcomes of 240 pancreas transplant procedures. Patient and graft survival rates were compared after 1, 3, and 5 years in both groups. Serum lipase, amylase, and C-reactive protein levels and incidence of surgical complications were evaluated at postoperative week 1. A subgroup analysis of 96 grafts (52 with histidine-tryptophanketoglutarate/44 with University of Wisconsin) with pancreas graft cold ischemic time ≥12 hours was also performed.

RESULTS

At mean follow-up of 75.2 ± 9.9 months, both groups demonstrated comparable short- and long-term patient survival. Overall, pancreas graft survival was slightly better in the histidine-tryptophan-ketoglutarate group (Kaplan-Meier analysis, log-rank P = .013). However, the subgroup analysis of grafts with cold ischemic time ≥12 hours showed slightly better pancreatic graft survival in the University of Wisconsin group, although not significantly (log-rank P = .95). Serum lipase and C-reactive protein levels at postoperative week 1 were higher in the histidinetryptophan-ketoglutarate group. Surgical complications were comparable. Multivariable Cox regression analysis identified neither solution as a risk factor affecting patient and graft survival.

CONCLUSIONS

Although a direct comparison between histidine-tryptophan-ketoglutarate and University of Wisconsin showed better pancreas graft survival with histidine-tryptophan-ketoglutarate, the multivariable analysis showed that the perfusion solution does not significantly influence patient and graft survival. However, in the analysis of transplants with cold ischemic time ≥12 hours, pancreas graft survival was slightly better in the University of Wisconsin group, although not significantly.

Complications during multiorgan retrieval and pancreas preservation

In pancreas transplantation, complications can arise at each step of the process, from the initial selection of donors and recipients through the surgical technique itself and the post-operative period, when lifelong immunosuppression is required. In the early steps, careful retrieval and preservation of the pancreas are crucial for the viability of the organ and ultimate success of the transplant. The pancreas is a low-flow gland, making it highly sensitive to transplantation conditions and presenting risk of pancreatitis due to periods of ischemia. The two groups of donors - after brain death (DBD) or after cardiac arrest (DCD) - require different strategies of retrieval and preservation to avoid or reduce the risk of complications developing during and after the transplantation. For DBD donor transplantation, multiorgan retrieval and cold preservation is the conventional technique. Asystole donor (DCD) transplantation, in contrast, can benefit from the newest technologies, such as hypothermic and especially normothermic preservation machines (referred to as NECMO), to optimize organ preservation. The latter has led to an increase in the pool of donors by facilitating recuperation of organs for transplantation that would have been discarded otherwise.

A systematic review and meta-analysis of cold in situ perfusion and preservation for pancreas transplantation

BACKGROUND

This study aimed to identify the most effective solution for in situ perfusion/preservation of the pancreas in donation after brain death donors, in addition to optimal in situ flush volume(s) and route(s) during pancreas procurement.

METHODS

Embase, Medline and Cochrane databases were utilized (1980-2017). Articles comparing graft outcomes between two or more different perfusion/preservation fluids (University of Wisconsin (UW), histidine-tryptophan-ketoglutarate (HTK) and/or Celsior) were compared using random effects models where appropriate.

RESULTS

Thirteen articles were included (939 transplants). Confidence in available evidence was low. A higher serum peak lipase (standardized mean difference 0.47, 95% CI 0.23-0.71, I² = 0) was observed in pancreatic grafts perfused/preserved with HTK compared to UW, but there were no differences in one-month pancreas allograft survivals or early thrombotic graft loss rates. Similarly, there were no significant differences in the rates of graft pancreatitis, thrombosis and graft survival between UW and Celsior solutions, and between aortic-only and dual aorto-portal perfusion.

CONCLUSION

UW cold perfusion may reduce peak serum lipase, but no quality evidence suggested UW cold perfusion improves graft survival and reduces thrombosis rates. Further research is needed to establish longer-term graft outcomes, the comparative efficacy of Celsior, and ideal perfusion volumes.

Preservation solutions used during abdominal transplantation: Current status and outcomes

Organ preservation remains an important contributing factor to graft and patient outcomes. During donor organ procurement and transportation, cellular injury is mitigated through the use of preservation solutions in conjunction with hypothermia. Various preservation solutions and protocols exist with widespread variability among transplant centers. In this review of abdominal organ preservation solutions, evolution of transplantation and graft preservation are discussed followed by classification of preservation solutions according to the composition of electrolytes, impermeants, buffers, antioxidants, and energy precursors. Lastly, pertinent clinical studies in the setting of hepatic, renal, pancreas, and intestinal transplantation are reviewed for patient and graft survival as well as financial considerations. In liver transplants there may be some benefit with the use of histidine-tryptophan-ketoglutarate (HTK) over University of Wisconsin solution in terms of biliary complications and potential cost savings. Renal grafts may experience increased initial graft dysfunction with the use of Euro-Collins thereby dissuading its use in support of HTK which can lead to substantial cost savings. University of Wisconsin solution and Celsior are favored in pancreas transplants given the concern for pancreatitis and graft thrombosis associated with HTK. No difference was observed with preservation solutions with respect to graft and patient survival in liver, renal, and pancreas transplants. Studies involving intestinal transplants are sparse but University of Wisconsin solution infused intraluminally in combination with an intra-vascular washout is a reasonable option until further evidence can be generated. Available literature can be used to ameliorate extensive variation across centers while potentially minimizing graft dysfunction and improving associated costs.

Perspectives on abdominal organ preservation solutions: a comparative literature review

Various preservation solutions are used for kidney, liver, pancreas, small intestine, and multiorgan recoveries and transplants. The effectiveness of these solutions, primarily measured by ability to preserve the organ and graft survival, was analyzed. The 2 most common solutions used for intra-abdominal organs are University of Wisconsin Solution (UW)/Viaspan and Histidine-tryptophan-ketoglutarate (HTK)/Custodiol solution. Outcomes for liver, pancreas, and kidney allografts preserved with these 2 solutions are similar. Although HTK solution shows conflicting results with respect to pancreatic cellular edema, researchers in several studies have noted that HTK solution may be more protective than UW solution against biliary complications in liver transplant. In kidney recoveries, HTK solution may be associated with higher graft loss and increased delayed graft function in marginal deceased donors but had lower incidence of delayed graft function in living donors when compared with UW. UW remains the reference standard for use during multiorgan recoveries but is experiencing strong competition from HTK and other alternative solutions. Some researchers suggest that Celsior's comparable results in abdominal organs and viability for thoracic organs makes it a strong competitor, especially in multiorgan recoveries. Each solution has benefits accompanied by disadvantages. Although it may not be feasible, when considering single-organ recoveries, consideration of alternative solutions may be warranted.

Diazoxide, a K(ATP) channel opener, prevents ischemia-reperfusion injury in rodent pancreatic islets

Diazoxide (DZ) is a pharmacological opener of ATP-sensitive K(+) channels that has been used for mimicking ischemic preconditioning and shows protection against ischemic damage. Here we investigated whether diazoxide supplementation to University of Wisconsin (UW) solution has cellular protection during islet isolation and improves in vivo islet transplant outcomes in a rodent ischemia model. C57/B6 mice pancreata were flushed with UW or UW + DZ solution and cold preserved for 6 or 10 h prior to islet isolation. Islet yield, in vitro and in vivo function, mitochondrial morphology, and apoptosis were evaluated. Significantly higher islet yields were observed in the UW + DZ group than in the UW group (237.5 ± 25.6 vs. 108.7 ± 49.3, p < 0.01). The islets from the UW + DZ group displayed a significantly higher glucose-induced insulin secretion (0.97 ng/ml ± 0.15 vs. 0.758 ng/ml ± 0.21, p = 0.009) and insulin content (60.96 ng/islet ± 13.94 vs. 42.09 ng/islet ± 8.15, p = 0.002). The DZ-treated islets had well-preserved mitochondrial morphology with superior responses of mitochondrial potentials, and calcium influx responded to glucose. A higher number of living cells and less late apoptotic cells were observed in the UW + DZ group (p < 0.05). Additionally, the islets from the UW + DZ group had a significantly higher cure rate and improved glucose tolerance. This study is the first to report mitoprotective effects of DZ for pancreas preservation and islet isolation. In the future, it will be necessary to further understand the underlying mechanism for the mitoprotection and to test this promising approach for pancreas preservation and the islet isolation process in nonhuman primates and ultimately humans.

Current state of pancreas preservation and implications for DCD pancreas transplantation

One of the main factors limiting potential uptake of pancreas transplantation, particularly in the United Kingdom, is the shortage of grafts. There has therefore been a recent expansion, particularly in the United Kingdom, in the utilization of grafts from donation after cardiac death (DCD) donors. These grafts are subjected to a greater ischemic insult and are arguably at higher risk of poor functional outcome. Although conventional preservation techniques may be adequate for donation after brain death (DBD) and low-risk DCD pancreases, as the number of DCD pancreas transplants increase and the threshold for rejecting organs decreases, the importance of optimal preservation techniques is going to increase. Over recent years, there have been significant advances in preservation techniques for DCD kidneys, improving the outcome of these marginal grafts. However, the use of such techniques for pancreas preservation is extremely limited and mainly historical. This overview describes the background and results of the established method of pancreas preservation for DBD, namely, cold static storage, and describes the use of the two-layer method. It also reviews pulsatile machine perfusion and normothermic perfusion for pancreas preservation techniques, which have shown promise in the preservation of DCD kidney grafts. The use of these techniques in pancreas preservation is predominantly historical but warrants reevaluation as to the feasibility of applying these techniques to DCD pancreas grafts not only for preservation but also for viability assessment. Further areas for development of pancreas preservation are discussed.

An experimental rat model of ex vivo lung perfusion for the assessment of lungs regarding histopathological findings and apoptosis: low-potassium dextran vs. histidine-tryptophan-ketoglutarate

OBJECTIVE

To compare histopathological findings and the degree of apoptosis among rat lungs preserved with low-potassium dextran (LPD) solution, histidine-tryptophan-ketoglutarate (HTK) solution, or normal saline (NS) at two ischemia periods (6 h and 12 h) using an experimental rat model of ex vivo lung perfusion.

METHODS

Sixty Wistar rats were anesthetized, randomized, and submitted to antegrade perfusion via pulmonary artery with one of the preservation solutions. Following en bloc extraction, the heart-lung blocks were preserved for 6 h or 12 h at 4 ºC and then reperfused with homologous blood for 60 min in an ex vivo lung perfusion system. At the end of the reperfusion, fragments of the middle lobe were extracted and processed for histopathological examination. The parameters evaluated were congestion, alveolar edema, alveolar hemorrhage, inflammatory infiltrate, and interstitial infiltrate. The degree of apoptosis was assessed using the TdT-mediated dUTP nick end labeling method.

RESULTS

The histopathological examination showed that all of the lungs preserved with NS presented alveolar edema after 12 h of ischemia. There were no statistically significant differences among the groups in terms of the degree of apoptosis.

CONCLUSIONS

In this study, the histopathological and apoptosis findings were similar with the use of either LPD or HTK solutions, whereas the occurrence of edema was significantly more common with the use of NS.

Donor risk factors, retrieval technique, preservation and ischemia/reperfusion injury in pancreas transplantation

PURPOSE OF REVIEW

Pancreas transplantation is still hampered by a high incidence of early graft loss, and organ quality concerns result in high nonrecovery/discard rates. Demographic donor characteristics, surgical retrieval strategy, preservation fluid and ischemia time are crucial factors in the process of organ selection and are discussed in this review.

RECENT FINDINGS

The donor shortage is driving an increasing utilization of nonideal organs which would previously have been identified as unsuitable. Recent literature suggests that organs from extended criteria donors - older (>45 years), BMI >30  kg/m(2), and donation after cardiac death (DCD) - can achieve the same graft and patient survival as those from standard criteria donors, with the proviso that the accumulation of risk factors and long ischemic times should be avoided. Visual assessment of the pancreas is advisable before declining/accepting a pancreas. University of Wisconsin represents the gold standard solution; however, histidine-tryptophan-ketoglutarate and Celsior result in equal outcomes if cold ischemia time (CIT) is less than 12  h. Currently in pancreas transplantation, there is no proven effective ischemia/reperfusion injury prophylaxis than trying to keep CIT as short as possible.

SUMMARY

Demographic risk factors, inspection of the pancreas by an experienced surgeon and predicted CIT are crucial factors in deciding whether to accept a pancreas for transplantation. However, there is a need for an improved evidence base to determine where to set the 'cut-off' for unsuitable pancreatic grafts.

Prevention and management of graft thrombosis in pancreatic transplant

Pancreatic transplant effectively cures type 1 diabetes mellitus and maintains consistent long-term euglycemia. However, technical failure, and in particular graft thrombosis, accounts for the vast majority of transplants lost in the early postoperative period. The pancreas' inherently low microvascular flow state makes it vulnerable to vascular complications, as does the hypercoagulable blood of diabetic patients. Ultimately, the phenomenon is most definitely multifactorial. Prevention, as opposed to treatment, is key and should focus on reducing these multiple risk factors. This will involve tactical donor selection, optimal surgical technique and some form of anticoagulation. Close monitoring and early intervention will be crucial when treating thrombosis once preventative methods have failed. This may be achieved by further anticoagulation, graft salvage, or pancreatectomy with retransplant. This article will explore the multiple factors contributing to graft thrombus formation and the ways in which they may be addressed to firstly prevent, or more likely, reduce thrombosis. Secondly, we will consider the management strategies which can be implemented once thrombosis has occurred.

Implication of mitochondrial cytoprotection in human islet isolation and transplantation

Islet transplantation is a promising therapy for type 1 diabetes mellitus; however, success rates in achieving both short- and long-term insulin independence are not consistent, due in part to inconsistent islet quality and quantity caused by the complex nature and multistep process of islet isolation and transplantation. Since the introduction of the Edmonton Protocol in 2000, more attention has been placed on preserving mitochondrial function as increasing evidences suggest that impaired mitochondrial integrity can adversely affect clinical outcomes. Some recent studies have demonstrated that it is possible to achieve islet cytoprotection by maintaining mitochondrial function and subsequently to improve islet transplantation outcomes. However, the benefits of mitoprotection in many cases are controversial and the underlying mechanisms are unclear. This article summarizes the recent progress associated with mitochondrial cytoprotection in each step of the islet isolation and transplantation process, as well as islet potency and viability assays based on the measurement of mitochondrial integrity. In addition, we briefly discuss immunosuppression side effects on islet graft function and how transplant site selection affects islet engraftment and clinical outcomes.

Comparing the performance of rat lungs preserved for 6 or 12 hours after perfusion with low-potassium dextran or histidine-tryptophan-ketoglutarate

INTRODUCTION

In lung transplantation, graft dysfunction is a frequent cause of mortality; the etiopathogenesis is related to ischemia-reperfusion injury. We sought to compare the lung performance of rats after reperfusion after presentation with 3 solutions at 2 ischemia times.

METHODS

We randomized 60 male Wistar rats to undergo anterograde perfusion via the pulmonary artery with low-potassium dextran (LPD), histidine-tryptophan ketoglutarate (HTK), or saline. After extraction, the heart-lung blocks were preserved in a solution at hypothermia for 6 or 12 hours before perfusion with homologous blood for 60 minutes using ex vivo system Isolated Perfused Rat or Guinea Pig Lung System (Harvard Apparatus). Respiratory mechanics, pulmonary weight, pulmonary artery pressure (PAP), and relative lung oxygenation capacity (ROC) measurements were obtained every 10 minutes.

RESULTS

Comparing tidal volume (TV), compliance, resistance, ROC, PAP, and pulmonary weight the LPD, HTK, and saline group did not differ at 6 and 12 hours. The TV was higher in the lungs with 6-hour ischemia in the LPD, HTK, and saline groups. Compliance was higher in the lungs with 6-hour ischemia in the LPD and saline groups. There were no differences in ROC values comparing lungs with 6- versus 12-hour ischemia in the LPD group. A significant difference was observed between lungs in the HTK and saline groups. Resistance was higher in the lungs with 12-hour ischemia among the LPD, HTK, and saline groups. There was a gradual weight increase in the lungs, particularly those undergoing 12-hour ischemia, despite the absence of a significant difference between groups.

CONCLUSION

Rat lungs perfused with LPD and HTK preservation solutions showed similar reperfusion performances in this ex-vivo perfusion model.

Pancreas procurement and preservation for islet transplantation: personal considerations

Pancreatic islet transplantation is a promising option for the treatment of type 1 diabetic patients. After the successful demonstration of the Edmonton protocol, islet transplantation has advanced significantly on several fronts, including improved pancreas procurement and preservation systems. Since we frequently use pancreata from donors after cardiac death in Japan,we have applied the in situ regional organ cooling system for pancreas procurement to reduce the warm ischemic time. To reduce the apoptosis of pancreatic tissue during cold preservation, we have applied the ductal injection of preservation solution. For pancreas preservation, we use modified Kyoto solution, which is advantageous at trypsin inhibition and less collagenase inhibition. In this paper, we show pancreas procurement and preservation in our group for islet transplantation.

The pancreas allograft donor: current status, controversies, and challenges for the future

The pancreas allograft is a scarce resource that is currently underutilized. The selection of appropriate deceased donors for pancreas procurement is of paramount importance for minimizing technical failure and optimizing long-term outcomes in pancreas transplantation. Despite the increasing demand for pancreas transplantation, increases in overall organ donation rates and the evolution of criteria that constitute an "acceptable" pancreas donor, the number of deceased donor pancreas transplants being performed in the United States has actually declined in recent years. Although there are many factors that must be considered during evaluation of the potential pancreas allograft donor to minimize morbidity and graft loss, it is evident that there are transplantable organs that are not used. In this review, deceased donor pancreas identification, management, selection, allocation, assessment, preservation, and the problem of pancreas underutilization will be discussed.

Hypotension after reperfusion in liver transplantation: histidine-tryptophan-ketoglutarate versus University of Wisconsin solution

BACKGROUND

The greatest hemodynamic instability during orthotopic liver transplantation occurs at graft reperfusion. Many factors have been implicated.

PURPOSE

To compare hemodynamic changes after reperfusion in grafted livers preserved with histidine-tryptophan-ketoglutarate (HTK) solution versus grafted livers preserved with University of Wisconsin (UW) solution.

METHODS

In this prospective study, we randomly divided 89 patients who underwent deceased donor liver transplantation into 2 groups: the UW group and the HTK group. The HTK group was further divided into 2 subgroups: flushed and not flushed before reperfusion. The patients were monitored with hemodynamic and metabolic parameters at 3 times: after the skin incision, 5 minutes before reperfusion, and 5 minutes after reperfusion.

RESULTS

Hemodynamic parameters in the UW group had not changed significantly at 5 minutes before reperfusion or 5 minutes after reperfusion (P = .45), and the incidence of hypotension after reperfusion in the UW group was 20%. In both HTK groups, the mean arterial pressure 5 minutes after reperfusion was significantly lower than at 5 minutes before reperfusion (P = .002); the incidence of hypotension after reperfusion in the nonflushed HTK group was 83.3% and in the flushed HTK group, 65.5%.

CONCLUSIONS

The incidence of hypotension after reperfusion is greater if HTK solution rather than UW solution is used. Flushing of grafted livers preserved with HTK solution might eliminate some vasoactive substances found in HTK solution.

Hypotension after Reperfusion in Liver Transplantation: Histidine-Tryptophan-Ketoglutarate versus University of Wisconsin Solution

Background

The greatest hemodynamic instability during orthotopic liver transplantation occurs at graft reperfusion. Many factors have been implicated.

Purpose

To compare hemodynamic changes after reperfusion in grafted livers preserved with histidine-tryptophan-ketoglutarate (HTK) solution versus grafted livers preserved with University of Wisconsin (UW) solution.

Methods

In this prospective study, we randomly divided 89 patients who underwent deceased donor liver transplantation into 2 groups: the UW group and the HTK group. The HTK group was further divided into 2 subgroups: flushed and not flushed before reperfusion. The patients were monitored with hemodynamic and metabolic parameters at 3 times: after the skin incision, 5 minutes before reperfusion, and 5 minutes after reperfusion.

Results

Hemodynamic parameters in the UW group had not changed significantly at 5 minutes before reperfusion or 5 minutes after reperfusion ( P= .45), and the incidence of hypotension after reperfusion in the UW group was 20%. In both HTK groups, the mean arterial pressure 5 minutes after reperfusion was significantly lower than at 5 minutes before reperfusion ( P = .002); the incidence of hypotension after reperfusion in the nonflushed HTK group was 83.3% and in the flushed HTK group, 65.5%.

Conclusions

The incidence of hypotension after reperfusion is greater if HTK solution rather than UW solution is used. Flushing of grafted livers preserved with HTK solution might eliminate some vasoactive substances found in HTK solution.

Histidine-tryptophan-ketoglutarate for pancreas allograft preservation: the Indiana University experience

Histidine-tryptophan-ketoglutarate solution (HTK) has been scrutinized for use in pancreas transplantation. A recent case series and a United Network for Organ Sharing data base review have suggested an increased incidence of allograft pancreatitis and graft loss with HTK compared to the University of Wisconsin solution (UW). Conversely, a recent randomized, controlled study failed to show any significant difference between HTK and UW for pancreas allograft preservation. This study was a retrospective review of all pancreas transplants performed at Indiana University between 2003 and 2009 comparing preservation with HTK or UW. Data included recipient and donor demographics, 7-day, 90-day and 1-year graft survival, peak 30-day serum amylase and lipase, HbA1c and C-peptide levels. Of the 308 pancreas transplants, 84% used HTK and 16% UW. There were more SPK compared to pancreas after kidney and pancreas transplant alone in the HTK group. Donor and recipient demographics were similar. There was no significant difference in 7-day, 90-day or 1-year graft survival, 30-day peak serum amylase and lipase, HbA1c or C-peptide. No clinically significant difference between HTK and UW for pancreas allograft preservation was identified. Specifically, in the context of low-to-moderate flush volume and short cold ischemia time (<or=10 h), no increased incidence of allograft pancreatitis or graft loss was observed.

Encapsulation of human islets in novel inhomogeneous alginate-ca2+/ba2+ microbeads: in vitro and in vivo function

Microencapsulation may allow for immunosuppression-free islet transplantation. Herein we investigated whether human islets can be shipped safely to a remote encapsulation core facility and maintain in vitro and in vivo functionality. In non-encapsulated islets before and encapsulated islets after shipment, viability was 88.3+/-2.5 and 87.5+/-2.7% (n=6, p=0.30). Stimulation index after static glucose incubation was 5.4+/-0.5 and 6.3+/-0.4 (n=6, p=0.18), respectively. After intraperitoneal transplantation, long-term normoglycemia was consistently achieved with 3,000, 5,000, and 10,000 IEQ encapsulated human islets. When transplanting 1,000 IEQ, mice returned to hyperglycemia after 30-55 (n=4/7) and 160 days (n=3/7). Transplanted mice showed human oral glucose tolerance with lower glucose levels than non-diabetic control mice. Capsules retrieved after transplantation were intact, with only minimal overgrowth. This study shows that human islets maintained the viability and in vitro function after encapsulation and the inhomogeneous alginate-Ca(2+)/Ba(2+) microbeads allow for long-term in vivo human islet graft function, despite long-distance shipment.

Human pancreatic islet isolation: Part II: purification and culture of human islets

Management of Type 1 diabetes is burdensome, both to the individual and society, costing over 100 billion dollars annually. Despite the widespread use of glucose monitoring and new insulin formulations, many individuals still develop devastating secondary complications. Pancreatic islet transplantation can restore near normal glucose control in diabetic patients, without the risk of serious hypoglycemic episodes that are associated with intensive insulin therapy. Providing sufficient islet mass is important for successful islet transplantation. However, donor characteristics, organ procurement and preservation affect the isolation outcome. At University of Illinois at Chicago (UIC) we developed a successful isolation protocol with an improved purification gradient. The program started in January 2004 and more than 300 isolations were performed up to November 2008. The pancreata were sent in cold preservation solutions (UW, University of Wisconsin or HTK, Histidine-Tryptophan Ketoglutarate) to the Cell Isolation Laboratory at UIC for islet isolation. Pancreatic islets were isolated using the UIC method, which is a modified version of the method originally described by Ricordi et al. As described in Part I: Digestion and Collection of Pancreatic Tissue, human pancreas was trimmed, cannulated, perfused, and digested. After collection and at least 30 minutes of incubation in UW solution, the tissue was loaded in the cell separator (COBE 2991, Cobe, Lakewood, CO) for purification. Following purification, islet yield (expressed as islet equivalents, IEQ), tissue volume, and purity was determined according to standard methods. Isolated islets were cultured in CMRL-1066 media (Mediatech, Herndon, VA), supplemented with 1.5% human albumin, 0.1% insulin-transferrin-selenium (ITS), 1 ml of Ciprofloxacin, 5 ml o f 1M HEPES, and 14.5 ml of 7.5% Sodium Bicarbonate in T175 flasks at 37 degrees C overnight culture before islets were transplanted or used for research.

Human pancreatic islet isolation: Part I: digestion and collection of pancreatic tissue

Management of Type 1 diabetes is burdensome, both to the individual and society, costing over 100 billion dollars annually. Despite the widespread use of glucose monitoring and new insulin formulations, many individuals still develop devastating secondary complications. Pancreatic islet transplantation can restore near normal glucose control in diabetic patients, without the risk of serious hypoglycemic episodes that are associated with intensive insulin therapy. Providing sufficient islet mass is important for successful islet transplantation. However, donor characteristic, organ procurement and preservation affect the isolation outcome. At University of Illinois at Chicago (UIC) we have developed a successful isolation protocol with an improved purification gradient. The program started in January 2004, and more than 300 isolations were performed up to November 2008. The pancreata were sent in cold preservation solutions (UW, University of Wisconsin or HTK, Histidine-Tryptophan Ketoglutarate) to the Cell Isolation Laboratory at UIC for islet isolation. Pancreatic islets were isolated using the UIC method, which is a modified version of the method originally described by Ricordi et al. Briefly, after cleaning the pancreas from the surrounding tissue, it was perfused with enzyme solution (Serva Collagenase + Neutral Protease or Sigma V enzyme). The distended pancreas was then transferred to the Ricordi digestion chamber, connected to a modified, closed circulation tubing system, and warmed up to 37 degrees C. During the digestion, the chamber was shaken gently. Samples were taken continuously to monitor the digestion progress. Once free islets were detected under the microscope, the digestion was stopped by flushing cold (4 degrees C) RPMI dilution solution (Mediatech, Herndon, VA) into the circulation system to dilute the enzyme. After being collected and washed in M199 media supplemented with human albumin, the tissue was sampled for pre-purification count and incubated with UW solution before purification. Purification process will be described in Part II: Purification and Culture of Human Islets.

Organ donation and utilization in the United States: 1998-2007

Organ transplantation remains the only life-saving therapy for many patients with organ failure. Despite the work of the Organ Donation and Transplant Collaboratives, and the marked increases in deceased donors early in the effort, deceased donors only rose by 67 from 2006 and the number of living donors declined during the same time period. There continue to be increases in the use of organs from donors after cardiac death (DCD) and expanded criteria donors (ECD). This year has seen a major change in the way organs are offered with increased patient safety measures in those organ offers made by OPOs using DonorNet. Unfortunately, the goals of 75% conversion rates, 3.75 organs transplanted per donor, 10% of all donors from DCD sources and 20% growth of transplant center volume have yet to be reached across all donation service areas (DSAs) and transplant centers; however, there are DSAs that have not only met, but exceeded, these goals. Changes in organ preservation techniques took place this year, partly due to expanding organ acceptance criteria and increasing numbers of ECDs and DCDs. Finally, the national transplant environment has changed in response to increased regulatory oversight and new requirements for donation and transplant provider organizations.

Histidine-tryptophan-ketoglutarate (HTK) is associated with reduced graft survival in pancreas transplantation

Prior single-center studies have reported that pancreas allograft survival is not affected by preservation in histidine-tryptophan-ketoglutarate (HTK) versus University of Wisconsin (UW) solution. To expand on these studies, we analyzed the United Network for Organ Sharing (UNOS) database of pancreas transplants from July 2004, through February 2008, to determine if preservation with HTK (N = 1081) versus UW (N = 3311) impacted graft survival. HTK preservation of pancreas allografts increased significantly in this time frame, from 15.4% in 2004 to 25.4% in 2008. After adjusting for other recipient, donor, graft and transplant center factors that impact graft survival, HTK preservation was independently associated with an increased risk of pancreas graft loss (hazard ratio [HR] 1.30, p = 0.014), especially in pancreas allografts with cold ischemia time (CIT) >or=12 h (HR 1.42, p = 0.017). This reduced survival with HTK preservation as compared to UW preservation was seen in both simultaneous pancreas-kidney (SPK) transplants and pancreas alone (PA) transplants. Furthermore, HTK preservation was also associated with a 1.54-fold higher odds of early (<30 days) pancreas graft loss as compared to UW (OR 1.54, p = 0.008). These results suggest that the increasing use of HTK for abdominal organ preservation should be re-examined.

Clinical experience with histidine-tryptophan-ketoglutarate solution in abdominal organ preservation: a review of recent literature

Histidine-tryptophan-ketoglutarate (HTK) solution was introduced by Bretschneider as a cardioplegia solution in the early 1980s and has subsequently been applied to organ preservation for transplantation in Europe during the 1980s and in North America during the last six yr. With the increasing use of HTK for primary preservation, it is important that the transplant community be aware of the properties of this solution and the advantages and disadvantages of its use. Even if a center uses an alternative preservation solution, it is likely that import offers will be made for allografts that have been preserved in HTK. In this review article, recent literature describing the clinical use of HTK in abdominal transplantation will be summarized with references to earlier reports when indicated.

Organ preservation in pancreas and islet transplantation

PURPOSE OF REVIEW

Organ preservation aims at reducing ischemia-reperfusion injury and maintains or even improves its function, and, therefore, increases transplant safety and efficiency. With the chronic lack of organs for transplantation, marginal donors are more and more frequently used in Western countries. New challenges, therefore, have to be met in organ preservation.

RECENT FINDINGS

We summarize the effects of cold preservation on various organ grafts, with particular emphasis on the pancreas. We review the different preservation solutions currently available in the clinic, and we present the current knowledge and clinical experience in pancreas and islet transplantation.

SUMMARY

Overall, in whole pancreas and islet transplantation, current cold preservation solutions (University of Wisconsin solution, Celsior, histidine-tryptophan-ketoglutarate) seem to be equivalent, with only few studies showing better results with University of Wisconsin solution. Regarding preservation with the two-layer method, conflicting results have been reported, and proper prospective controlled studies have yet to be performed to gather evidence on its impact on islet yield and function. Some recent developments and future strategies in general organ preservation not yet applied to pancreas preservation are reviewed at the end of the article.

Technical refinements in small bowel transplantation

PURPOSE OF REVIEW

This review focuses on the recently described or revised refinements or innovations in small bowel transplantation.

RECENT FINDINGS

Changes in donor selection criteria; cadaveric procurement techniques; organ preservation solutions; management of the recipient abdominal wall; technical modifications, pitfalls and recommendations to be applied during the engraftment as well as intestinal living donation will be covered.

SUMMARY

Intestinal transplantation has evolved over time to become a clinically accepted therapy for patients with intestinal failure. Short- and long-term results have improved. The surgical procedures have been standardized and the applications broaden, but there have been recently published refinements that might affect the future results of clinical intestinal transplantation and guide research.

Pancreas preservation for pancreas and islet transplantation

PURPOSE OF REVIEW

To summarize advances and limitations in pancreas procurement and preservation for pancreas and islet transplantation, and review advances in islet protection and preservation.

RECENT FINDINGS

Pancreases procured after cardiac death, with in-situ regional organ cooling, have been successfully used for islet transplantation. Colloid-free Celsior and histidine-tryptophan-ketoglutarate preservation solutions are comparable to University of Wisconsin solution when used for cold storage before pancreas transplantation. Colloid-free preservation solutions are inferior to University of Wisconsin solution for pancreas preservation prior to islet isolation and transplantation. Clinical reports on pancreas transplants suggest that the two-layer method may not offer significant benefits over cold storage with the University of Wisconsin solution: improved oxygenation may depend on the graft size; benefits in experimental models may not translate to human organs. Improvements in islet yield and quality occurred from pancreases treated with inhibitors of stress-induced apoptosis during procurement, storage, isolation or culture desirable before islet isolation and transplantation and may improve islet yield and quality. Methods for real-time, noninvasive assessment of pancreas quality during preservation have been implemented and objective islet-potency assays have been developed and validated. These innovations should contribute to objective evaluation and establishment of improved pancreas-preservation and islet-isolation strategies.

SUMMARY

Cold storage may be adequate for preservation before pancreas transplants, but insufficient when pancreases are processed for islets or when expanded donors are used. Supplementation of cold-storage solutions with cytoprotective agents and perfusion may improve pancreas and islet transplant outcomes.

A prospective randomized multicenter trial comparing histidine-tryptophane-ketoglutarate versus University of Wisconsin perfusion solution in clinical pancreas transplantation

We aimed to evaluate early pancreas transplant graft function after histidine-tryptophan-ketoglutarate (HTK) versus University of Wisconsin (UW) perfusion. Prospective randomized multicenter study including 68 pancreas transplantations stratified according to preservation fluid used (27 HTK vs. 41 UW). Primary endpoint was pancreas graft survival at 6 months. Serum alpha-amylase, lipase, C-peptide, HbA1C and exogenous insulin requirement were compared at several time points. Mean pancreas cold ischemia time was 10.8 +/- 3.7 (HTK) vs. 11.8 +/- 3.4 h (UW) (P = 0.247). Simultaneous pancreas-kidney transplantation was performed in 95.6% of the patients, pancreas transplantation alone in 2.9%, and pancreas after kidney transplantation in 1.5%. Six months graft survival was 85.2% (HTK) vs. 90.2% (UW) (P = 0.703). Serum amylase and lipase values did not differ between both the groups during the observation period. C-peptide levels were elevated in both the groups without significant differences at each time point. Higher exogenous insulin requirement early after transplantation in the UW group had resolved at 3 months. Six month patient survival was 96.3% (HTK) vs. 100% (UW) (P = 0.397). With a mean cold ischemia time of 10 h in this study, HTK and UW solutions appear to be equally suitable for perfusion and organ preservation in clinical pancreas transplantation.

Comparative Analysis of Clinical Efficacy and Cost between University of Wisconsin Solution and Histidine-Tryptophan-Ketoglutarate

Objective

To compare University of Wisconsin solution (Viaspan), the universal standard for organ preservation, with histidine-tryptophan-ketoglutarate solution. An analysis of each solution, in reference to clinical trials with specific organs, is presented and assessed to find the efficacy of each in a clinical environment. Also to view each solution from an economical standpoint, and in the end develop an overall understanding of the key similarities and differences between each solution in order to assess appropriate use of each in a clinical setting.

Data Sources

A literature search was conducted by using PubMed, MEDLINE, BIOSIS, Embase, and other online data bases to find the most recent studies of University of Wisconsin and histidine-tryptophan-ketoglutarate solutions. Search terms included University of Wisconsin solution, histidine-tryptophan-ketoglutarate, preservation solution, cost analysis, biliary complication, and other related subjects.

Study Selection

Previous research was selected from the literature search to provide basic information on the 2 solutions and also to provide clinical examples of each solution and the efficacy of each with specific organs.

Data Synthesis

Information and published articles on the 2 solutions were gathered for descriptive and comparative purposes.

Conclusions

The 2 solutions appear equally effective in organ preservation. Each solution has its own organ-specific qualities, and each has different complications. The studies reviewed here indicate that the differences are minor and thus suggest that the 2 solutions are equally acceptable for clinical use. Of the 2 solutions, histidine-tryptophan-ketoglutarate costs less than University of Wisconsin solution.

Increased pancreatitis in allografts flushed with histidine-tryptophan-ketoglutarate solution: a cautionary tale

We reviewed pancreas transplantation outcomes after Histidine-Tryptophan-Ketoglutarate (HTK) and University of Wisconsin (UW) preservation solution use between 2001 and 2007 at two transplant centers. While equivalence has been claimed for kidney and liver transplant outcomes after the use of HTK or UW preservation solution, consensus has not been reached on equivalence when flushing pancreata. Others have reported comparable patient and graft survival rates, but found an association between the use of HTK and an increase in the incidence of acute rejection and pancreatitis. In reviewing our experiences, we found in pancreata flushed with HTK a higher incidence of postoperative complications including graft pancreatitis, use of octreotide and a decreased rate of insulin-independence at hospital discharge. These findings prompted us to critically review our centers' experience to determine if there is a basis for suspecting a causal relationship.

Pancreas preservation for pancreas and islet transplantation

PURPOSE OF REVIEW

To summarize advances and limitations in pancreas procurement and preservation for pancreas and islet transplantation, and review advances in islet protection and preservation.

RECENT FINDINGS

Pancreases procured after cardiac death, with in-situ regional organ cooling, have been successfully used for islet transplantation. Colloid-free Celsior and histidine-tryptophan-ketoglutarate preservation solutions are comparable to University of Wisconsin solution when used for cold storage before pancreas transplantation. Colloid-free preservation solutions are inferior to University of Wisconsin solution for pancreas preservation prior to islet isolation and transplantation. Clinical reports on pancreas and islet transplants suggest that the two-layer method may not offer significant benefits over cold storage with the University of Wisconsin solution: improved oxygenation may depend on the graft size; benefits in experimental models may not translate to human organs. Improvements in islet yield and quality occurred from pancreases treated with inhibitors of stress-induced apoptosis during procurement, storage, isolation or culture. Pancreas perfusion may be desirable before islet isolation and transplantation and may improve islet yields and quality. Methods for real-time, noninvasive assessment of pancreas quality during preservation have been implemented and objective islet potency assays have been developed and validated. These innovations should contribute to objective evaluation and establishment of improved pancreas preservation and islet isolation strategies.

SUMMARY

Cold storage may be adequate for preservation before pancreas transplants, but insufficient when pancreases are processed for islets or when expanded donors are used. Supplementation of cold storage solutions with cytoprotective agents and perfusion may improve pancreas and islet transplant outcomes.

Organ preservation with histidine-tryptophan ketogluatarate solution in clinical pancreas transplantation: an update of the indiana university experience

In May 2003, University of Wisconsin (UW) solution was replaced with Histidine-Tryptophan Ketoglutarate (HTK) solution as the preservation fluid for abdominal organ procurements in our center. Herein we have reported our updated results with HTK in pancreas transplantation. Between May 2003 and October 2006, 152 pancreas transplantations were performed in which 146 used HTK. The procedures were as follows: simultaneous kidney pancreas transplantation (n = 85; 55%), pancreas after kidney transplantation (n = 41; 30%), and solitary pancreas transplantation (n = 20; 15%). Donor and recipient data were collected with primary outcomes as primary nonfunction (PNF), and 30-day and 1-year graft and patient survival. Patient demographics are as follows: age (36 +/- 12 years), gender (males, 89: females, 57), race (white, 135; African American, 11). Mean flush volume was 3.8 +/- 1 L. The mean cold ischemia time was 8 +/- 3 hours. Mean warm ischemia time was 48 +/- 23 minutes. There were no cases of PNF in this cohort. Thirty-day and 1-year patient survival rates were 99% and 95%, respectively. The 30-day and 1-year graft survivals rates were 95% and 93%, respectively. There were 10 grafts lost with 7 vascular complications (6 venous and 1 arterial thrombosis). There were 2 cases of chronic rejection and 1 graft lost to noncompliance. These statistics compare favorably with International Pancreas Transplant Registry reported 1-year survival for pancreas allografts. All other patients were insulin independent by discharge. Serum fasting blood glucose and serial amylase remained comparable at all intervals posttransplantation to those of a historical UW cohort. Within this range of cold ischemia times, HTK appears to provide effective pancreas preservation.

Comparison of histidine-tryptophan-ketoglutarate solution and University of Wisconsin solution in extended criteria liver donors

Liver, pancreas, and kidney allografts preserved in histidine-tryptophan-ketoglutarate (HTK) and University of Wisconsin (UW) solutions have similar clinical outcomes. This study compares HTK and UW in a large number of standard criteria donor (SCD) and extended criteria donor (ECD) livers at a single center over 5 years. All adult, cadaveric liver and liver-kidney transplants performed between July 1, 2001 and June 30, 2006 were reviewed (n = 698). There were 435 livers (62%) categorized as ECD for severe physiologic stress and 70 (10%) because of old age. Recipient outcomes included perioperative death or graft loss and overall survival. Liver enzymes were analyzed for the first month post-transplant. Biliary complications were assessed through chart review. Overall, 371 donor livers were preserved in HTK (53%), and 327 were preserved in UW (47%). There were no statistically significant differences in any of the primary outcome measures comparing HTK and UW. The HTK group overall had a higher day 1 median aspartate aminotransferase and alanine aminotransferase, but the two groups were similar in function thereafter. HTK was superior to UW in protection against biliary complications. Kaplan-Meier graft survival curves failed to demonstrate a significant difference in SCD or ECD livers. In conclusion, HTK and UW are not clinically distinguishable in this large sample of liver transplants, although HTK may be protective against biliary complications when compared to UW. These findings persisted for both SCD and ECD livers. Given the lower cost per donor for HTK, this preservation solution may be preferable for general use.

Comparison of M-Kyoto solution and histidine-tryptophan-ketoglutarate solution with a trypsin inhibitor for pancreas preservation in islet transplantation

The use of University of Wisconsin (UW) preservation solution in islet transplantation has some disadvantages, including inhibition of collagenase activity for pancreatic digestion. Histidine-tryptophan-ketoglutarate (HTK) solution has demonstrated an efficacy similar to UW solution for organ preservation in clinical pancreas transplantation. Recently, we reported that islet yield from porcine pancreata was significantly gtreater when they were preserved using M-Kyoto solution compared with UW solution. Here, we compared HTK solution with ulinastatin (M-HTK) and M-Kyoto solution for islet yield. In porcine islet isolation, islet yield after purification was significantly greater in the M-Kyoto/perfluorochemical (PFC) group compared with the M-HTK/PFC group. The M-Kyoto/PFC group had a significantly lower ADP/ATP ratio compared with the M-HTK/PFC group, suggesting that different islet yields might be due to the differences as energy sources of the solutions used. In conclusion, M-Kyoto/PFC solution is better for pancreas preservation before islet isolation than M-HTK/PFC solution.

Improved outcomes in islet isolation and transplantation by the use of a novel hemoglobin-based O2 carrier

During isolation, islets are exposed to warm ischemia. In this study, intraductal administration of oxygenated polymerized, stroma-free hemoglobin-pyridoxalated (Poly SFH-P) was performed to improve O2 delivery. Rat pancreata subjected to 30-min warm ischemia were perfused intraductally with collagenase in oxygenated Poly SFH-P/RPMI or RPMI (control). PO2 was increased by Poly SFH-P (381.7 +/- 35.3 mmHg vs. 202.3 +/- 28.2, p = 0.01) and pH maintained within physiological range (7.4-7.2 vs. 7.1-6.6, p = 0.009). Islet viability (77% +/- 4.6 vs. 63% +/- 4.7, p = 0.04) was improved and apoptosis lower with Poly SFH-P (caspase-3: 34,714 +/- 2167 vs. 45,985 +/- 1382, respectively, p = 0.01). Poly SFH-P improved islet responsiveness to glucose as determined by increased intracellular Ca2+ levels and improved insulin secretion (SI 5.4 +/- 0.1 vs. 3.1 +/- 0.2, p = 0.03). Mitochondrial integrity was improved in Poly SFH-P-treated islets, which showed higher percentage change in membrane potential after glucose stimulation (14.7% +/- 1.8 vs. 9.8 +/- 1.4, respectively, p < 0.05). O2 delivery by Poly SFH-P did not increase oxidative stress (GSH 7.1 +/- 2.9 nm/mg protein for Poly SFH-P vs. 6.8 +/- 2.4 control, p = 0.9) or oxidative injury (MDA 1.8 +/- 0.9 nmol/mg protein vs. 6.2 +/- 2.4, p = 0.19). Time to reach normoglycemia in transplanted diabetic nude mice was shorter (1.8 +/- 0.4 vs. 7 +/- 2.5 days, p = 0.02), and glucose tolerance improved in the Poly SFH-P group (AUC 8106 +/- 590 vs. 10,863 +/- 946, p = 0.03). Oxygenated Poly SFH-P improves islet isolation and transplantation outcomes by preserving mitochondrial integrity.

Human Islet Isolation Outcomes From Pancreata Preserved with Histidine-Tryptophan Ketoglutarate versus University of Wisconsin Solution

This study was designed to compare Histadine-Tryptophan-Ketogluterate (HTK) with University of Wisconsin (UW) solution. Pancreata from extended criteria donors were flushed and transported with HTK (n=41) or UW (n=45). Isolation outcomes were determined by islet yields, viability and in vitro and in vivo function. Final yields were similar between two groups (HTK: 383,085 vs. UW: 328,514 EIN, P=0.14). In the HTK group, 63.4% (26/41) of isolations resulted in a yield of over 300,000, and in the UW group this was achieved in 46.7% (21/45; P=0.12). Viability results were similar (HTK: 82.9 vs. UW: 82.7%, P=0.93). Stimulation index in the HTK and UW groups were comparable (5.28 vs. 4.91, P=0.62). Ten out of 41 islet preparations in HTK and 4 of 45 in UW group were suitable for clinical transplantation (P=0.05). Our study shows HTK is equivalent to UW solution in the preservation of pancreata for islet isolation.

Early pancreas transplant outcomes with histidine-tryptophan-ketoglutarate preservation: a multicenter study

Little is known about the use of histidine-tryptophan-ketoglutarate (HTK) preservation solution for pancreas preservation. We compared early pancreas graft outcomes at four pancreas transplant programs within the state of Michigan in 2002 and 2003 (University of Wisconsin [UW] era) with those in 2004 (HTK era). The primary endpoint was early graft loss. The UW group (n=41) and the HTK group (n=36) had similar outcomes with respect to: technical graft loss (9.8% vs. 8.3%, P=NS), 90-day graft function (90.2% vs. 86.1%, P=NS), and rate of pancreatic leak/abscess (12.2% vs. 11.1%, P=NS). There were also no significant differences in postoperative amylase and lipase levels between the two groups. The HTK group did have significantly more acute rejection within the first 180 days (25.0% vs. 9.8%, P<0.05). HTK is a suitable substitute for UW in the preservation of pancreas allografts.

Follow-up experience using histidine-tryptophan ketoglutarate solution in clinical pancreas transplantation

In May 2003, at Indiana University, the standard cold preservation solution University of Wisconsin (UW) solution was replaced by histidine-tryptophan ketogluatarate (HTK) solution. Earlier, we presented our initial experience with HTK in pancreas preservation with an analysis of the first 10 pancreas transplants. Here we report updated results with HTK in pancreas transplantation over the past 18 months. Between May 2003 and March 2005, a total of 87 pancreas transplants were performed with 78 of these organs utilizing HTK. Seventy five patients received 78 organ transplants. Surgical procedures performed were: simultaneous kidney pancreas transplantation (n = 50, 64%), pancreas after kidney transplantation (n = 19, 24%), solitary pancreas transplantation (n = 9, 12%). Donor and recipient data were collected with primary outcomes as primary nonfunction and 30-day graft and patient survivals, and compared to the UW cohort from our original report. Donor and recipient demographics were similar. Mean follow-up time is 12 +/- 6 months. The mean cold ischemia time was 9 +/- 3 hours. There were no cases of primary graft nonfunction. Thirty-day and 1-year patient survivals were 99% and 93%. The 30-day and 1-year graft survivals were 96% and 93%. There were five grafts lost, including three within the first month (two venous and one arterial thrombosis). There was one case of chronic rejection and one noncompliance. All other patients were insulin-independent by discharge. Serum fasting blood glucose and serial amylase remained comparable at all intervals posttransplantation. Within this range of cold ischemia time, HTK appears to provide effective pancreas preservation.

Comparison of histidine-tryptophan ketoglutarate solution and University of Wisconsin solution in prolonged cold preservation of kidney allografts

Although University of Wisconsin (UW) solution is the standard preservation solution for organ transplantation, Histidine-Tryptophan Ketogluatarate (HTK) solution has been increasingly used. This study compared HTK or UW for cold static storage of kidney allografts. In all, 149 renal transplants were performed with cold ischemic times (CI) greater than 16 hr (UW 87, HTK 62) and a subset analysis was performed with CI over 24 hr (HTK 31, UW 38). Data from receiving renal transplant centers focused on delayed graft function (DGF), patient and allograft survival. In CI greater than 16 hr, graft and patient survival were comparable. HTK cohort had lower DGF. In CI greater than 24 hr, there was no difference in patient survival, a trend towards improved graft survival in HTK, and decreased rate of DGF in HTK. This data suggests that UW and HTK have at least similar efficacy in kidney preservation at longer ischemic times.

Comparison of histidine-tryptophan-ketoglutarate solution (HTK) and University of Wisconsin solution (UW) in adult liver transplantation

Histidine-tryptophan-ketoglutarate solution (HTK) and University of Wisconsin solution (UW) have been shown to have similar outcomes in cadaveric kidney, pancreas, and liver transplantation. Our institution changed from UW to HTK as the primary preservation solution for liver, kidney and pancreas transplantation. This study compares the perioperative and first year outcomes of liver transplantation using UW or HTK. Primary use of HTK began on May 1, 2003. We reviewed the records of all adult liver transplant recipients from July 1, 2002 to December 31, 2004. Recipients were compared based on organ preservation solution (UW n = 204, HTK n = 174). Outcomes included 1-, 6- and 12-month graft and patient survival and 1-, 7-, 14-, and 30-day liver function and serum creatinine. During the entire study period, the two groups were managed similarly in operative technique, immunosuppressive regimens, and donor liver criteria. Over 30 months, 378 adult patients underwent liver transplantation. There were no significant differences between UW and HTK in 1-, 6-, or 12-month graft or patient survival. The HTK group had a higher day 1 median AST, ALT, and total bilirubin, but the two groups were similar thereafter. An anticipated difference in infused volume between UW and HTK was demonstrated. In conclusion, to our knowledge, this is the first reported large case series from North America comparing HTK and UW in liver transplantation with 2- to 12-month follow-up. There were no significant differences between HTK and UW in this population when comparing 1 month graft function and first-year graft and patient survival.