Utilization of organs from donors after circulatory death for vascularized pancreas and islet of Langerhans transplantation: recommendations from an expert group

Islet Transplantation: Current Limitations and Challenges for Successful Outcomes

Islet transplantation is a promising approach for treating patients with unstable T1DM. However, it is confronted with numerous obstacles throughout the various stages of the transplantation procedure. Significant progress has been made over the last 25 years in understanding the mechanisms behind the loss of functional islet mass and in developing protective strategies. Nevertheless, at present, two to three pancreases are still needed to treat a single patient, which limits the maximal number of patients who can benefit from islet transplantation. Thus, this publication provides an overview of recent scientific findings on the various issues affecting islet transplantation. Specifically, we will focus on the understanding of the mechanisms involved and the strategies developed to alleviate these problems from the isolation stage to the post-transplantation phase. Finally, we hope that this review will highlight new avenues of action, enabling us to propose pancreatic islet transplantation to a maximum number of patients with T1DM.

Exploring Preservation Modalities in a Split Human Pancreas Model to Investigate the Effect on the Islet Isolation Outcomes

BACKGROUND

In islet transplantation, the use of dynamic hypothermic preservation techniques is a current challenge. This study compares the efficacy of 3 pancreas preservation methods: static cold storage, hypothermic machine perfusion (HMP), and oxygenated HMP.

METHODS

A standardized human pancreas split model was employed using discarded organs from both donation after brain death (n = 15) and donation after circulatory death (DCD) (n = 9) donors. The pancreas head was preserved using static cold storage (control group), whereas the tail was preserved using the 3 different methods (study group). Data on donor characteristics, pancreas histology, isolation outcomes, and functional tests of isolated islets were collected.

RESULTS

Insulin secretory function evaluated by calculating stimulation indices and total amount of secreted insulin during high glucose stimulation (area under the curve) through dynamic perifusion experiments was similar across all paired groups from both DCD and donation after brain death donors. In our hands, islet yield (IEQ/g) from the pancreas tails used as study groups was higher than that of the pancreas heads as expected although this difference did not always reach statistical significance because of great variability probably due to suboptimal quality of organs released for research purposes. Moreover, islets from DCD organs had greater purity than controls (P ≤ 0.01) in the HMP study group. Furthermore, our investigation revealed no significant differences in pancreas histology, oxidative stress markers, and apoptosis indicators.

CONCLUSIONS

For the first time, a comparative analysis was conducted, using a split model, to assess the effects of various preservation methods on islets derived from pancreas donors. Nevertheless, no discernible variances were observed in terms of islet functionality, histological attributes, or isolation efficacy. Further investigations are needed to validate these findings for clinical application.

Clinical Translation of Bio-Artificial Pancreas Therapies: Ethical, Legal and Psychosocial Interdisciplinary Considerations and Key Recommendations

The field of regenerative medicine offers potential therapies for Type 1 Diabetes, whereby metabolically active cellular components are combined with synthetic medical devices. These therapies are sometimes referred to as "bioartificial pancreases." For these emerging and rapidly developing therapies to be clinically translated to patients, researchers must overcome not just scientific hurdles, but also navigate complex legal, ethical and psychosocial issues. In this article, we first provide an introductory overview of the key legal, ethical and psychosocial considerations identified in the existing literature and identify areas where research is currently lacking. We then highlight two principal areas of concern in which these discrete disciplines significantly overlap: 1) individual autonomy and 2) access and equality. Using the example of beta-cell provenance, we demonstrate how, by harnessing an interdisciplinary approach we can address these key areas of concern. Moreover, we provide practical recommendations to researchers, clinicians, and policymakers which will help to facilitate the clinical translation of this cutting-edge technology for Type 1 Diabetes patients. Finally, we emphasize the importance of exploring patient perspectives to ensure their responsible and acceptable translation from bench to body.

Whole-Organ Pancreas and Islets Transplantations in UK: An Overview and Future Directions

Whole-organ pancreas and islets transplantations are two therapeutic options to treat type 1 diabetic patients resistant to optimised medical treatment in whom severe complications develop. Selection of the best option for β-cell replacement depends on several factors such as kidney function, patient comorbidities, and treatment goals. For a patient with end-stage kidney disease, the treatment of choice is often a simultaneous transplant of the pancreas and kidney (SPK). However, it remains a major surgical procedure in patients with multiple comorbidities and therefore it is important to select those who will benefit from it. Additionally, in view of the organ shortage, new strategies to improve outcomes and reduce immune reactions have been developed, including dynamic organ perfusion technologies, pancreas bioengineering, and stem cell therapies. The purpose of this article is to review the indications, surgical techniques, outcomes, and future directions of whole-organ pancreas and islets transplantations.

Sterile Pancreas Inflammation during Preservation and after Transplantation

The pancreas is very susceptible to ischemia-reperfusion injury. Early graft losses due to pancreatitis and thrombosis represent a major issue after pancreas transplantation. Sterile inflammation during organ procurement (during brain death and ischemia-reperfusion) and after transplantation affects organ outcomes. Sterile inflammation of the pancreas linked to ischemia-reperfusion injury involves the activation of innate immune cell subsets such as macrophages and neutrophils, following tissue damage and release of damage-associated molecular patterns and pro-inflammatory cytokines. Macrophages and neutrophils favor tissue invasion by other immune cells, have deleterious effects or functions, and promote tissue fibrosis. However, some innate cell subsets may promote tissue repair. This outburst of sterile inflammation promotes adaptive immunity activation via antigen exposure and activation of antigen-presenting cells. Better controlling sterile inflammation during pancreas preservation and after transplantation is of utmost interest in order to decrease early allograft loss (in particular thrombosis) and increase long-term allograft survival. In this regard, perfusion techniques that are currently being implemented represent a promising tool to decrease global inflammation and modulate the immune response.

Every islet matters: improving the impact of human islet research

Detailed characterization of human pancreatic islets is key to elucidating the pathophysiology of all forms of diabetes, especially type 2 diabetes. However, access to human pancreatic islets is limited. Pancreatic tissue for islet retrieval can be obtained from brain-dead organ donors or from individuals undergoing pancreatectomy, often referred to as 'living donors'. Different protocols for human islet procurement can substantially impact islet function. This variability, coupled with heterogeneity between individuals and islets, results in analytical challenges to separate genuine disease pathology or differences between human donors from experimental noise. There are currently no international guidelines for human donor phenotyping, islet procurement and functional characterization. This lack of standardization means that substantial investments from multiple international efforts towards improved understanding of diabetes pathology cannot be fully leveraged. In this Perspective, we overview the status of the field of human islet research, highlight the challenges and propose actions that could accelerate research progress and increase understanding of type 2 diabetes to slow its pandemic spreading.

Impact of insulin therapy before donation on graft outcomes in pancreas transplantation: An analysis of the OPTN/UNOS database

AIMS

Information on the impact of insulin therapy before pancreas donation on pancreas outcomes is scarce. We aim to explore the influence of insulin therapy before donation on recipient and pancreas graft survival.

METHODS

Registry study including 12,841 pancreas recipients from the OPTN/UNOS registry performed between 2000 and 2017. Inverse probability of treatment weighting (IPTW) was used to account for covariate imbalance between recipients from a donor with and without insulin requirements.

RESULTS

A total of 7765 (60%) patients received a pancreas from a donor with insulin before donation (IBD). Pancreas graft survival (death-censored) was similar between recipients from IBD and non-IBD donors at 1, 5 and 10 years (89% vs 89%, 78% vs 79 and 69% vs 70%, respectively, P = 0.35). Recipients from IBD donors presented a similar 90-days pancreas graft survival. After IPTW weighting, IBD donors were neither associated with any post-transplant surgical complication (HR 1.11 [95% CI 0.98-1.24], P = 0.06), nor with risk for recipient death (HR 0.94 [95% CI 0.85-1.04], P = 0.26), nor pancreas graft failure (HR 1.06 [95% CI 0.98-1.16], P = 0.15).

CONCLUSIONS

Insulin therapy before donation in accepted pancreas donors was not associated, per se, with an impaired pancreas graft and patient survival.

Outcomes after simultaneous pancreas-kidney transplantation from donation after circulatory death donors: A UK registry analysis

There are concerns that simultaneous pancreas-kidney (SPK) transplants from donation after circulatory death (DCD) donors have a higher risk of graft failure than those from donation after brain death (DBD) donors. A UK registry analysis of SPK transplants between 2005 and 2018 was performed. Pancreas survivals of those receiving organs from DCD or DBD donors were compared. Multivariable analyses were used to adjust for baseline differences between the two groups and to identify factors associated with pancreas graft loss. A total of 2228 SPK transplants were implanted; 403 (18.1%) were from DCD donors. DCD donors were generally younger, slimmer, less likely to have stroke as a cause of death, with lower terminal creatinines and shorter pancreas cold ischemic times than DBD donors. Median (IQR) follow-up was 4.2 (1.6-8.1) years. On univariable analysis, there were no statistically significant differences in 5-year death-censored pancreas graft survival between the two donor types (79.5% versus 80.4%; p = .86). Multivariable analysis showed no statistically significant differences in 5-year pancreas graft loss between transplants from DCD (n = 343) and DBD (n = 1492) donors (hazard ratio 1.26, 95% CI 0.76-1.23; p = .12). The findings from this study support the increased use of SPK transplants from DCD donors.

A systematic review and meta-analyses of regional perfusion in donation after circulatory death solid organ transplantation

In donation after circulatory death (DCD), (thoraco)abdominal regional perfusion (RP) restores circulation to a region of the body following death declaration. We systematically reviewed outcomes of solid organ transplantation after RP by searching PubMed, Embase, and Cochrane libraries. Eighty-eight articles reporting on outcomes of liver, kidney, pancreas, heart, and lung transplants or donor/organ utilization were identified. Meta-analyses were conducted when possible. Methodological quality was assessed using National Institutes of Health (NIH)-scoring tools. Case reports (13/88), case series (44/88), retrospective cohort studies (35/88), retrospective matched cohort studies (5/88), and case-control studies (2/88) were identified, with overall fair quality. As blood viscosity and rheology change below 20 °C, studies were grouped as hypothermic (HRP, ≤20 °C) or normothermic (NRP, >20 °C) regional perfusion. Data demonstrate that RP is a safe alternative to in situ cold preservation (ISP) in uncontrolled and controlled DCDs. The scarce HRP data are from before 2005. NRP appears to reduce post-transplant complications, especially biliary complications in controlled DCD livers, compared with ISP. Comparisons for kidney and pancreas with ISP are needed but there is no evidence that NRP is detrimental. Additional data on NRP in thoracic organs are needed. Whether RP increases donor or organ utilization needs further research.

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.

Donor Predictors of Donor Pancreas Retrieval and Subsequent Solid Pancreas Transplantation in Australia and New Zealand from 2007 to 2016

BACKGROUND

Donor characteristics help guide donor pancreas acceptance for solid pancreas-kidney transplantation; however, these criteria vary worldwide. Such variation could result in nonuse of potentially transplantable organs. Using a registry cohort, we identified donor characteristics associated with donor pancreas retrieval and subsequent solid pancreas transplantation in Australia and New Zealand.

METHODS

Australia and New Zealand Organ Donor registry donor data from 2007 to 2016 were used to define cohort 1 (all donors authorized for pancreas retrieval) and cohort 2 (all retrieved donor pancreata considered for solid pancreas transplantation). Donor factors significantly associated with donor pancreas retrieval (cohort 1) and solid pancreas transplantation of retrieved donor pancreata (cohort 2) were determined via multivariable logistic regression.

RESULTS

Nonretrieval and nonuse of solid organ donor pancreas increased throughout the study period, and nonauthorization for pancreas donation remained stable. Donor body mass index, sex, and viral serology were associated with donor pancreas retrieval but not transplantation. Donor age, cause of death, donation after brain death status, terminal serum creatinine, and donor region were associated with both donor pancreas retrieval and acceptance for solid pancreas transplantation with donation after brain death status being the strongest predictor for both outcomes.

CONCLUSIONS

Donor age, cause of death, donation after brain death status, terminal serum creatinine, and donor region were associated with both donor pancreas retrieval and subsequent transplantation in Australia and New Zealand. Subsequent correlation of these factors with post-pancreas transplant outcomes would help guide pancreas transplant decisions and minimize nonuse of potentially usable donor pancreata.

Hypothermic oxygenated machine perfusion of the human pancreas for clinical islet isolation: a prospective feasibility study

Due to an increasing scarcity of pancreases with optimal donor characteristics, islet isolation centers utilize pancreases from extended criteria donors, such as from donation after circulatory death (DCD) donors, which are particularly susceptible to prolonged cold ischemia time (CIT). We hypothesized that hypothermic machine perfusion (HMP) can safely increase CIT. Five human DCD pancreases were subjected to 6 h of oxygenated HMP. Perfusion parameters, apoptosis, and edema were measured prior to islet isolation. Five human DBD pancreases were evaluated after static cold storage (SCS). Islet viability, and in vitro and in vivo functionality in diabetic mice were analyzed. Islets were isolated from HMP pancreases after 13.4 h [12.9–14.5] CIT and after 9.2 h [6.5–12.5] CIT from SCS pancreases. Histological analysis of the pancreatic tissue showed that HMP did not induce edema nor apoptosis. Islets maintained >90% viable during culture, and an appropriate in vitro and in vivo function in mice was demonstrated after HMP. The current study design does not permit to demonstrate that oxygenated HMP allows for cold ischemia extension; however, the successful isolation of functional islets from discarded human DCD pancreases after performing 6 h of oxygenated HMP indicates that oxygenated HMP may be a useful technology for better preservation of pancreases.

Consensus statement on normothermic regional perfusion in donation after circulatory death: report from the European Society for Organ Transplantation's Transplant Learning Journey

Normothermic regional perfusion (NRP) in donation after circulatory death (DCD) is a safe alternative to in situ cooling and rapid procurement. An increasing number of countries and centres are performing NRP, a technically and logistically challenging procedure. This consensus document provides evidence-based recommendations on the use of NRP in uncontrolled and controlled DCDs. It also offers minimal ethical, logistical and technical requirements that form the foundation of a safe and effective NRP programme. The present article is based on evidence and opinions formulated by a panel of European experts of Workstream 04 of the Transplantation Learning Journey project, which is part of the European Society for Organ Transplantation.

Pancreas Transplantation from Donors after Circulatory Death: an Irrational Reluctance?

PURPOSE OF REVIEW

Beta-cell replacement is the best therapeutic option for patients with type 1 diabetes. Because of donor scarcity, more extended criteria donors are used for transplantation. Donation after circulatory death donors (DCD) are not commonly used for pancreas transplantation, because of the supposed higher risk of complications. This review gives an overview on the pathophysiology, risk factors, and outcome in DCD transplantation and discusses different preservation methods.

RECENT FINDINGS

Studies on outcomes of DCD pancreata show similar results compared with those of donation after brain death (DBD), when accumulation of other risk factors is avoided. Hypothermic machine perfusion is shown to be a safe method to improve graft viability in experimental settings. DCD should not be the sole reason to decline a pancreas for transplantation. Adequate donor selection and improved preservation techniques can lead to enhanced pancreas utilization and outcome.

Machine Perfusion and the Pancreas: Will It Increase the Donor Pool?

PURPOSE OF REVIEW

Pancreas transplantation enables complete patient independence from exogenous insulin administration and increases both patient survival and quality of life. Despite this, there has been a decline in pancreas transplantation for the past 20 years, influenced by changing donor demographics with more high-risk extended criteria (ECD) and donation after cardiac death (DCD) donors. This review discusses whether the advent of machine perfusion (MP), if extended to the pancreas, can increase the pool of suitable donor organs.

RECENT FINDINGS

Hypothermic and normothermic MP, as forms of preservation deemed superior to cold storage for high-risk kidney and liver donor organs, have opened the avenue for translation of this work into the pancreas. Recent experimental models of porcine and human ex-vivo pancreatic MP are promising. Applications of MP to the pancreas however need refinement-focusing on perfusion protocols and viability assessment tools. Emerging research shows pancreatic MP can potentially offer superior preservation capacity, the ability to both resuscitate and manipulate organs, and assess functional and metabolic organ viability. The future of MP will lie in organ assessment and resuscitation after retrieval, where ultimately organs initially considered high risk and unsuitable for transplantation will be optimised and transformed, making them then available for clinical use, thus increasing the pool of suitably viable pancreata for transplantation.

Pancreatic Islet Transplantation in Humans: Recent Progress and Future Directions

Pancreatic islet transplantation has become an established approach to β-cell replacement therapy for the treatment of insulin-deficient diabetes. Recent progress in techniques for islet isolation, islet culture, and peritransplant management of the islet transplant recipient has resulted in substantial improvements in metabolic and safety outcomes for patients. For patients requiring total or subtotal pancreatectomy for benign disease of the pancreas, isolation of islets from the diseased pancreas with intrahepatic transplantation of autologous islets can prevent or ameliorate postsurgical diabetes, and for patients previously experiencing painful recurrent acute or chronic pancreatitis, quality of life is substantially improved. For patients with type 1 diabetes or insulin-deficient forms of pancreatogenic (type 3c) diabetes, isolation of islets from a deceased donor pancreas with intrahepatic transplantation of allogeneic islets can ameliorate problematic hypoglycemia, stabilize glycemic lability, and maintain on-target glycemic control, consequently with improved quality of life, and often without the requirement for insulin therapy. Because the metabolic benefits are dependent on the numbers of islets transplanted that survive engraftment, recipients of autoislets are limited to receive the number of islets isolated from their own pancreas, whereas recipients of alloislets may receive islets isolated from more than one donor pancreas. The development of alternative sources of islet cells for transplantation, whether from autologous, allogeneic, or xenogeneic tissues, is an active area of investigation that promises to expand access and indications for islet transplantation in the future treatment of diabetes.

A steady decline in pancreas transplantation rates

BACKGROUND/OBJECTIVES

After years of growth in many pancreas transplant programs, UNOS has reported declining transplant numbers in the USA. This precipitating trend urges for an evaluation of the transplant numbers and scientific productivity in the Eurotransplant region and the UK.

METHODS

We performed a trend analysis of pancreas transplantation rates, between 1997 and 2016, adjusting for changes in population size, and an analysis of scientific publications in this field. We used information from the UNOS, Eurotransplant, and UK transplant registry and bibliometric information from the Web of Science database.

RESULTS

Between 2004 and 2016 there was an average annual decline in pancreas transplantation rates per million inhabitants of 3.3% in the USA and 2.5% in the Eurotransplant region. In the UK, transplant numbers showed an average annual decline of 1.0% from 2009 to 2016. Publications in Q1 journals showed an annual change of -2.1% and +20.1%, before 2004, and a change of -3.8% and -5.5%, between 2004 and 2016, for USA and Eurotransplant publications, respectively.

CONCLUSIONS

Adjusting pancreas transplantation rates for changes in population size showed a clear decline in transplant numbers in both the USA and Eurotransplant region, with first signs of decline in the UK. Following this trend, the number of scientific publications in this field have declined worldwide.

Novel Fusion Protein Targeting Mitochondrial DNA Improves Pancreatic Islet Functional Potency and Islet Transplantation Outcomes

Long-term graft survival is an ongoing challenge in the field of islet transplantation. With the growing demand for transplantable organs, therapies to improve organ quality and reduce the incidence of graft dysfunction are of paramount importance. We evaluated the protective role of a recombinant DNA repair protein targeted to mitochondria (Exscien I-III), as a therapeutic agent using a rodent model of pancreatic islet transplantation. We first investigated the effect of therapy on isolated rat islets cultured with pro-inflammatory cytokines (interleukin-1 β, interferon γ, and tumor necrosis factor α) for 48 h and documented a significant reduction in apoptosis by flow cytometry, improved viability by immunofluorescence, and conserved functional potency in vitro and in vivo in Exscien I-III-treated islets. We then tested the effect of therapy in systemic inflammation using a rat model of donor brain death (BD) sustained for a 6-h period. Donor rats were allocated to 4 groups: (non-BD + vehicle, non-BD + Exscien I-III, BD + vehicle, and BD + Exscien I-III) and treated with Exscien I-III (4 mg/kg) or vehicle 30 min after BD induction. Sham (non-BD)-operated animals receiving either Exscien I-III or vehicle served as controls. Islets purified from BD + Exscien I-III-treated donors showed a significant increase in glucose-stimulated insulin release in vitro when compared to islets from vehicle-treated counterparts. In addition, donor treatment with Exscien I-III attenuated the effects of BD and significantly improved the functional potency of transplanted islets in vivo. Our data indicate that mitochondrially targeted antioxidant therapy is a novel strategy to protect pancreas and islet quality from the deleterious effects of cytokines in culture and during the inflammatory response associated with donation after BD. The potential for rapid translation into clinical practice makes Exscien I-III an attractive therapeutic option for the management of brain-dead donors or as an additive to islets in culture after isolation setting.

β Cell Replacement Therapy: The Next 10 Years

β cell replacement with either pancreas or islet transplantation has progressed immensely over the last decades with current 1- and 5-year insulin independence rates of approximately 85% and 50%, respectively. Recent advances are largely attributed to improvements in immunosuppressive regimen, donor selection, and surgical technique. However, both strategies are compromised by a scarce donor source. Xenotransplantation offers a potential solution by providing a theoretically unlimited supply of islets, but clinical application has been limited by concerns for a potent immune response against xenogeneic tissue. β cell clusters derived from embryonic or induced pluripotent stem cells represent another promising unlimited source of insulin producing cells, but clinical application is pending further advances in the function of the β cell like clusters. Exciting developments and rapid progress in all areas of β cell replacement prompted a lively debate by members of the young investigator committee of the International Pancreas and Islet Transplant Association at the 15th International Pancreas and Islet Transplant Association Congress in Melbourne and at the 26th international congress of The Transplant Society in Hong Kong. This international group of young investigators debated which modality of β cell replacement would predominate the landscape in 10 years, and their arguments are summarized here.

Hypothermic Oxygenated Machine Perfusion of the Human Donor Pancreas

Supplemental digital content is available in the text.

Background

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

Methods

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

Results

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

Conclusions

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

Organ donor pancreases for the study of human islet cell histology and pathophysiology: a precious and valuable resource

Direct in vivo assessment of pancreatic islet-cells for the study of the pathophysiology of diabetes in humans is hampered by anatomical and technological hurdles. To date, most of the information that has been generated is derived from histological studies performed on pancreatic tissue from autopsy, surgery, in vivo biopsy or organ donation. Each approach has its advantages and disadvantages (as summarised in this commentary); however, in this edition of Diabetologia, Kusmartseva et al ( https://doi.org/10.1007/s00125-017-4494-x ) provide further evidence to support the use of organ donor pancreases for the study of human diabetes. They show that length of terminal hospitalisation of organ donors prior to death does not seem to influence the frequency of inflammatory cells infiltrating the pancreas and the replication of beta cells. These findings are reassuring, demonstrating the reliability of this precious and valuable resource for human islet cells research.

Donors after circulatory death pancreas transplantation

PURPOSE OF REVIEW

The use of organs from donors after circulatory death (DCD) has become standard practice in solid organ transplantation of most abdominal organs and has been used successfully in some centres for pancreas transplantation. Nevertheless, concerns regarding poor graft outcomes and complications remain. This review aims to discuss the current state of DCD pancreas transplantation and the associated outcomes.

RECENT FINDINGS

In many countries, whereas the number of donors after brainstem death (DBD) remains stable, the mean age and BMI have increased making these donors, previously considered to be low risk, now more marginal. Recent meta-analyses have confirmed previous single-centre and registry reports that graft and patient survival after DCD pancreas transplantation are comparable with outcomes using pancreases from DBD donors; DCD pancreas transplantation is now common practice in several countries in Europe, particularly the United Kingdom. Although there have been reports of higher thrombosis rates after DCD pancreas transplantation, the significance of this is difficult to judge as the impact has not been seen in overall graft survival.

SUMMARY

Pancreas transplantation using DCD organs is well tolerated and feasible when other risk factors are minimized. Although there has been some evidence of an increased risk of thrombosis, this has not translated into a significant difference in graft survival.

[Research progress on the donor cell sources of pancreatic islet transplantation for treatment of diabetes mellitus]

Objective

To summarize the research progress on the source and selection of donor cells in the field of islet replacement therapy for diabetes mellitus.

Methods

Domestic and abroad literature concerning islet replacement therapy for diabetes mellitus, as well as donor source and donor selection was reviewed and analyzed thoroughly.

Results

The shortage of donor supply is still a major obstacle for the widely clinical application of pancreatic islet transplantation (PIT). Currently, in addition to the progress on the allogeneic/autologous donor islet supply, some remarkable achievements have been also attained in the application of xenogeneic islet (from pig donor), as well as islet like cells derived from stem cells and islet cell line, potentially enlarging the source of implantable cells.

Conclusion

Adequate and suitable donor cell supply is an essential prerequisite for widely clinical application of PIT therapy for type 1 diabetes mellitus (T1DM). Further perfection of organ donation system, together with development of immune-tolerance induction, gene and bioengineering technology etc. will possibly solve the problem of donor cell shortage and provide a basis for clinical application of cellular replacement therapy for T1DM.

[Non-heart-beating donors are ineligible]

The death of the donor is a mandatory prerequisite for organ transplantation (dead donor rule) worldwide. It is a medical, legal and ethical consensus to accept the concept of brain death, as first proposed in 1968 by the ad hoc committee of the Harvard Medical School, as a certain criterion of death. In isolated cases where the diagnosis of brain death was claimed to be wrong, it could be demonstrated that the diagnostic procedure for brain death had not been correctly performed. In March 2014 a joint statement by the German neuromedical societies emphasized that 1) the diagnosis of brain death is one of the safest diagnoses in medicine if performed according to accepted medical standards and criteria and 2) the concept of non-heart-beating donors (NHBD, i. e. organ donation after an arbitrarily defined duration of circulatory and cardiac arrest) practiced in some European countries must be absolutely rejected because it implicates a high risk of diagnostic error. According to the current literature it is unclear at what time cardiac and circulatory arrest is irreversible and leads to irreversible cessation of all functions of the entire brain including the brainstem, even though clinical signs of cessation of brain functions are always found after 10 min. Furthermore, is it often an arbitrary decision to exactly define the duration of cardiac arrest if continuous echocardiographic monitoring has not been carried out from the very beginning. Last but not least there are ethical concerns against the concept of NHBD because it might influence therapeutic efforts to resuscitate a patient with cardiac arrest. Therefore, the German Medical Council (BÄK) has repeatedly rejected the concept of NHBD for organ transplantation since 1995.