Sequential kidney/islet transplantation: efficacy and safety assessment of a steroid-free immunosuppression protocol

Allo Beta Cell transplantation: specific features, unanswered questions, and immunological challenge

Type 1 diabetes (T1D) presents a persistent medical challenge, demanding innovative strategies for sustained glycemic control and enhanced patient well-being. Beta cells are specialized cells in the pancreas that produce insulin, a hormone that regulates blood sugar levels. When beta cells are damaged or destroyed, insulin production decreases, which leads to T1D. Allo Beta Cell Transplantation has emerged as a promising therapeutic avenue, with the goal of reinstating glucose regulation and insulin production in T1D patients. However, the path to success in this approach is fraught with complex immunological hurdles that demand rigorous exploration and resolution for enduring therapeutic efficacy. This exploration focuses on the distinct immunological characteristics inherent to Allo Beta Cell Transplantation. An understanding of these unique challenges is pivotal for the development of effective therapeutic interventions. The critical role of glucose regulation and insulin in immune activation is emphasized, with an emphasis on the intricate interplay between beta cells and immune cells. The transplantation site, particularly the liver, is examined in depth, highlighting its relevance in the context of complex immunological issues. Scrutiny extends to recipient and donor matching, including the utilization of multiple islet donors, while also considering the potential risk of autoimmune recurrence. Moreover, unanswered questions and persistent gaps in knowledge within the field are identified. These include the absence of robust evidence supporting immunosuppression treatments, the need for reliable methods to assess rejection and treatment protocols, the lack of validated biomarkers for monitoring beta cell loss, and the imperative need for improved beta cell imaging techniques. In addition, attention is drawn to emerging directions and transformative strategies in the field. This encompasses alternative immunosuppressive regimens and calcineurin-free immunoprotocols, as well as a reevaluation of induction therapy and recipient preconditioning methods. Innovative approaches targeting autoimmune recurrence, such as CAR Tregs and TCR Tregs, are explored, along with the potential of stem stealth cells, tissue engineering, and encapsulation to overcome the risk of graft rejection. In summary, this review provides a comprehensive overview of the inherent immunological obstacles associated with Allo Beta Cell Transplantation. It offers valuable insights into emerging strategies and directions that hold great promise for advancing the field and ultimately improving outcomes for individuals living with diabetes.

Cell Therapy for Type 1 Diabetes: From Islet Transplantation to Stem Cells

The field of cell therapy of type 1 diabetes is a particularly interesting example in the scenario of regenerative medicine. In fact, β-cell replacement has its roots in the experience of islet transplantation, which began 40 years ago and is currently a rapidly accelerating field, with several ongoing clinical trials using β cells derived from stem cells. Type 1 diabetes is particularly suitable for cell therapy as it is a disease due to the deficiency of only one cell type, the insulin-producing β cell, and this endocrine cell does not need to be positioned inside the pancreas to perform its function. On the other hand, the presence of a double immunological barrier, the allogeneic one and the autoimmune one, makes the protection of β cells from rejection a major challenge. Until today, islet transplantation has taught us a lot, pioneering immunosuppressive therapies, graft encapsulation, tissue engineering, and test of different implant sites and has stimulated a great variety of studies on β-cell function. This review starts from islet transplantation, presenting its current indications and the latest published trials, to arrive at the prospects of stem cell therapy, presenting the latest innovations in the field.

Felix dies natalis, insulin… ceterum autem censeo "beta is better"

One hundred years after its discovery, insulin remains the life-saving therapy for many patients with diabetes. It has been a 100-years-old success story thanks to the fact that insulin therapy has continuously integrated the knowledge developed over a century. In 1982, insulin becomes the first therapeutic protein to be produced using recombinant DNA technology. The first "mini" insulin pump and the first insulin pen become available in 1983 and 1985, respectively. In 1996, the first generation of insulin analogues were produced. In 1999, the first continuous glucose-monitoring device for reading interstitial glucose was approved by the FDA. In 2010s, the ultra-long action insulins were introduced. An equally exciting story developed in parallel. In 1966. Kelly et al. performed the first clinical pancreas transplant at the University of Minnesota, and now it is a well-established clinical option. First successful islet transplantations in humans were obtained in the late 1980s and 1990s. Their ability to consistently re-establish the endogenous insulin secretion was obtained in 2000s. More recently, the possibility to generate large numbers of functional human β cells from pluripotent stem cells was demonstrated, and the first clinical trial using stem cell-derived insulin producing cell was started in 2014. This year, the discovery of this life-saving hormone turns 100 years. This provides a unique opportunity not only to celebrate this extraordinary success story, but also to reflect on the limits of insulin therapy and renew the commitment of the scientific community to an insulin free world for our patients.

Pancreas collagen digestion during islet of Langerhans isolation-a prospective study

The success of pancreas islet isolation largely depends on donor characteristics, including extracellular matrix composition of which collagen is the main element. We hypothesized that isolation yields are proportional to collagen digestion percentage, and aimed to determine a threshold that predicts isolation success. The amount of pancreas collagen (I-V) was determined using colorimetry prior to and after the digestion process in 52 human islet isolations. Collagen I-V and VI were also assessed histologically. We identified a collagen digestion threshold of ≥ 60% as an independent factor beyond which an islet preparation has a ninefold increased odds of yielding ≥ 250 000 islet equivalents (IEQ) (P = 0.009) and a sixfold increased odds of being transplanted (P = 0.015). Preparations with ≥ 60% collagen digestion (n = 35) yielded 283 017 ± 164 214 IEQ versus 180 142 ± 85 397 in the < 60% collagen digestion group (n = 17) (P = 0.016); respectively 62.9% versus 29.4% of those were transplanted (P = 0.024). Common donor characteristics, initial collagen content, enzyme blend, and digestion times were not associated with collagen digestion percentage variations. Donor age positively correlated with the amount of collagen VI (P = 0.013). There was no difference in islet graft survival between high and low digestion groups. We determined that a 60% pancreas collagen digestion is the threshold beyond which an islet isolation is likely to be successful and transplanted.

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.

Tissue-engineering approaches in pancreatic islet transplantation

Pancreatic islet transplantation is a promising alternative to whole-pancreas transplantation as a treatment of type 1 diabetes mellitus. This technique has been extensively developed during the past few years, with the main purpose of minimizing the complications arising from the standard protocols used in organ transplantation. By using a variety of strategies used in tissue engineering and regenerative medicine, pancreatic islets have been successfully introduced in host patients with different outcomes in terms of islet survival and functionality, as well as the desired normoglycemic control. Here, we describe and discuss those strategies to transplant islets together with different scaffolds, in combination with various cell types and diffusible factors, and always with the aim of reducing host immune response and achieving islet survival, regardless of the site of transplantation.

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

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

Portal Venous Interventions: State of the Art

In recent decades, there have been numerous advances in the management of liver cancer, cirrhosis, and diabetes mellitus. Although these diseases are wide ranging in their clinical manifestations, each can potentially be treated by exploiting the blood flow dynamics within the portal venous system, and in some cases, adding cellular therapies. To aid in the management of these disease states, minimally invasive transcatheter portal venous interventions have been developed to improve the safety of major hepatic resection, to reduce the untoward effects of sequelae from end-stage liver disease, and to minimize the requirement of exogenously administered insulin for patients with diabetes mellitus. This state of the art review therefore provides an overview of the most recent data and strategies for utilization of preoperative portal vein embolization, transjugular intrahepatic portosystemic shunt placement, balloon retrograde transvenous obliteration, and islet cell transplantation.

The Impact of c-Fos/Activator Protein-1 Inhibition on Allogeneic Pancreatic Islet Transplantation

Unpreventable allograft rejection is one of the main problems in pancreatic islet transplantation (PIT). Therefore, it is imperative to develop a more effective immunosuppressive strategy. The blockade of transcription factors has been a central part of T cell-depleting immunosuppressive therapies, as typified by the use of calcineurin inhibitors. The inhibition of activator protein-1 (AP-1) offers a novel strategy for immunosuppression in PIT, although to date, no reports on the effects of AP-1 inhibition are available. In this study, we investigated the immunosuppressive effects of T-5224, a c-Fos/AP-1-selective inhibitor, on murine T cells activated by αCD3+αCD28 mAbs. T-5224 inhibited proliferation, CD25 up-regulation, and the production of IL-2 and interferon-γ. In addition, T-5224 blocked the nuclear translocation of c-Fos/AP-1 in activated murine T cells. In BALB/c (H-2(d) )-to-C57BL/6J (H-2(b) ) mouse PIT, the 2-week administration of T-5224 prolonged survival of 600 islet allografts in a dose-dependent manner. When combined with a 2-week low-dose tacrolimus, the T-5224 treatment markedly prolonged allograft survival to over 300 days, while the efficacy was indeterminate when transplanted islet allograft mass was reduced to 300. We conclude that the c-Fos/AP-1 inhibition by T-5224 is a potentially attractive strategy for allogeneic PIT.

Treating diabetes with islet transplantation: lessons from the past decade in Lille

Type 1 diabetes (T1D) is due to the loss of both beta-cell insulin secretion and glucose sensing, leading to glucose variability and a lack of predictability, a daily issue for patients. Guidelines for the treatment of T1D have become stricter as results from the Diabetes Control and Complications Trial (DCCT) demonstrated the close relationship between microangiopathy and HbA1c levels. In this regard, glucometers, ambulatory continuous glucose monitoring, and subcutaneous and intraperitoneal pumps have been major developments in the management of glucose imbalance. Besides this technological approach, islet transplantation (IT) has emerged as an acceptable safe procedure with results that continue to improve. Research in the last decade of the 20th century focused on the feasibility of islet isolation and transplantation and, since 2000, the success and reproducibility of the Edmonton protocol have been proven, and the mid-term (5-year) benefit-risk ratio evaluated. Currently, a 5-year 50% rate of insulin independence can be expected, with stabilization of microangiopathy and macroangiopathy, but the possible side-effects of immunosuppressants, limited availability of islets and still limited duration of insulin independence restrict the procedure to cases of brittle diabetes in patients who are not overweight or have no associated insulin resistance. However, various prognostic factors have been identified that may extend islet graft survival and reduce the number of islet injections required; these include graft quality, autoimmunity, immunosuppressant regimen and non-specific inflammatory reactions. Finally, alternative injection sites and unlimited sources of islets are likely to make IT a routine procedure in the future.

Practical and critical instruction for nonhuman primate diabetic models

Diabetes mellitus, a disease of metabolic dysregulation, is characterized by inappropriate hyperglycemia resulting from progressive loss of insulin secretion or action. The potential of nonhuman primate (NHP) models in diabetes research has been well understood. NHPs have long been regarded as the "gold standard" for preclinical studies. However, there are persistent, severe obstacles to the development and application of these models. At present, a consensus for standardized strategies of diabetic induction has not been achieved. The different modeling methods of diabetes has led to various characterizations of the pathology of the disease; however, there are deficiencies of systemic evaluation programs for nonhuman primate diabetes models. In this scenario, experimental systemic programs provide the highly required guidelines for NHP diabetic models. Moreover, given the expensive and relatively small population of primates and the fatal diabetic complications, it is imperative to carefully manage the care and use of these animals in biomedical research studies. This article briefly reviews the technical and managerial aspects of NHP diabetes models providing practical and critical instruction on housing and care, routine management, development strategy, modeling diagnosis, evaluation, and disease control, as well as guidelines for model selection for various purposes. The present article sought to provide guidelines for NHP models of diabetes in their development and application. It is not intended to outline mandatory requirements for clinical accreditation.

Posttransplant Cellular Immune Reactivity against Donor Antigen Correlates with Clinical Islet Transplantation Outcome: Towards a Better Posttransplant Monitoring

The aim of the present study was to assess the efficiency of cell-based immune assays in the detection of alloreactivity after islet transplantation and to correlate these results with clinical outcome. Mixed lymphocyte cultures were performed with peripheral blood mononuclear cells from recipients ( n = 14), donors, or third party. The immune reactivity was assessed by the release of IFN-γ (ELISpot), cell proliferation (FACS analysis for Ki67), and cytokine quantification (Bioplex). Islet function correlated with the number of IFN-γ-secreting cells following incubation with donor cells ( p = 0.007, r = –0.50), but not with third party cells ( p = 0.61). Similarly, a high number of donor-specific proliferating cells was associated with a low islet function ( p = 0.006, r = −0.51). Proliferating cells were mainly CD3+CD4+ lymphocytes and CD3-CD56+ natural killer cells (with low levels of CD3+CD8+ lymphocytes). Patients with low islet function had increased levels of CD4+Ki67+cells ( p ≤ 0.0001), while no difference was observed in CD8+Ki67+ and CD56+Ki67+ cells. IFN-γ, IL-5, and IL-17 levels were increased in patients with low islet function, but IL-10 levels tended to be lower. IFN-γ-ELISpot, proliferation, and cytokines were similarly accurate in predicting clinical outcome (AUC = 0.77 ± 0.088, 0.85 ± 0.084, and 0.88 ± 0.074, respectively). Cellular immune reactivity against donor cells correlates with posttransplant islet function. The tested assays have the potential to be of substantial help in the management of islet graft recipients and deserve prospective validation.

Comparative impact on islet isolation and transplant outcome of the preservation solutions Institut Georges Lopez-1, University of Wisconsin, and Celsior

BACKGROUND

Institut Georges Lopez-1 (IGL-1) is a preservation solution similar to University of Wisconsin (UW) with reversed Na/K contents. In this study, we assessed the impact of IGL-1, UW, and Celsior (CS) solutions on islet isolation and transplant outcome.

METHODS

We retrospectively analyzed 376 islet isolations from pancreases flushed and transported with IGL-1 (n=95), UW (n=204), or CS (n=77). We determined isolation outcome and β-cell function in vitro. Transplanted patients were divided into three groups depending on preservation solution of pancreas, and islet graft function was assessed by decrease in daily insulin needs, C-peptide/glucose ratios, β-scores, and transplant estimated function at 1- and 6-month follow-up.

RESULTS

IGL-1, UW, and CS groups were similar according to donor age, body mass index, and pancreas weight. There was no difference in islet yields between the three groups. Success rates, transplant rates, β-cell secretory function, and viability were similar for all three groups. We observed no difference in decreased insulin needs, C-peptide glucose ratios, β-scores, and transplant estimated function at 1- and 6-month follow-up between IGL-1, UW, and CS groups.

CONCLUSIONS

Our study shows that IGL-1 is equivalent to UW or CS solutions for pancreas perfusion and cold storage before islet isolation and transplantation.

Oral immunosuppressive medication for growing pigs in transplantation studies

Immunosuppressive (IS) medication is needed to avoid graft rejection in porcine transplantation models. An ideal IS therapy should have no side-effects, but increased susceptibility to infections, disturbed intestinal microflora and toxic effects on organs and tissues are commonly reported. The aim of the present study was to design an IS protocol with tacrolimus and mycophenolic acid to be used for maintenance therapy in the post-transplant period. An eligible whole blood trough value for tacrolimus was 5–15 μg/L. Conventional specific pathogen-free pigs were fitted with an indwelling catheter under general anaesthesia, and after the acclimatization period three groups were formed: group A ( n= 4) received 0.15 mg/kg body weight (BW) twice daily tacrolimus and 500 mg twice daily mycophenolic acid; group B ( n= 4) received 0.3 mg/kg BW twice daily tacrolimus and 500 mg twice daily mycophenolic acid; group C ( n= 2) did not receive any medication. Daily clinical examinations and analyses of blood concentrations of tacrolimus and glucose were performed. Total and differential white blood cell counts, enzyme activities, bilirubin and electrolyte concentrations were measured every fourth day. At the end of the experiment, the pigs were killed with an overdose of pentobarbital intravenously and a necropsy was performed immediately. All animals seemed to tolerate the IS treatment well. No alterations in their clinical state of health were observed throughout the study and daily weight gain was similar for the three groups. The necropsy did not reveal any pathological findings related to medication. The study showed that 0.25 mg/kg BW twice daily tacrolimus and 500 mg twice daily mycophenolic acid would be an appropriate maintenance dosage for conventional pigs.

Pancreatic islet cell transplantation: an update for interventional radiologists

Pancreatic islet cell transplantation is a promising cellular-based therapy for type 1 diabetes mellitus. This procedure involves portal venous injection of islet cells and affords 1-year insulin independence in as many as 80% of recipients. Although transplant surgeons represent historical drivers of islet therapy, requirement for image guidance and transcatheter techniques has fostered collaboration with interventional radiologists, who are positioned to play a significant role in clinical performance of islet transplantation and in basic science research in this field. This review article aims to familiarize interventional radiologists with islet cell transplantation patient selection, procedure technique, clinical outcomes, and future clinical and research avenues.

Impact of the number of infusions on 2-year results of islet-after-kidney transplantation in the GRAGIL network

BACKGROUND

Insulin independence after islet transplantation is generally achieved after multiple infusions. However, single infusion would increase the number of recipients. Our aim was to evaluate the results of islet-after-kidney transplantation according to the number of infusions.

METHODS

Islets were isolated at the Geneva University, shipped, and transplanted into French patients from the Swiss-French GRAGIL network, on the "Edmonton" immunosuppression protocol between 2004 and 2010.

RESULTS

Nineteen patients were transplanted with 33 preparations. Fifteen patients reached 24 months follow-up; eight subjects were single-graft recipients and seven were double-graft recipients. Finally, single-graft recipients received a median of 5312 islet equivalents/kg (5186-6388) vs. 10,564 (10,054-11,375) for double-graft recipients (P=0.0003) with similar islet mass at first infusion. Insulin independence was achieved in five of eight single-graft subjects (62.5%) versus five of seven in double-graft subjects (71.4%), not significant. Median insulin independence duration was 4.7 (3.1-15.2) months after one infusion vs. 19 (9.6-20.8) months after two infusions (not significant). At 24 months posttransplant, comparing single- with double-graft patients, insulin doses were 0.23 (0.11-0.34) U/kg vs. 0.02 (0.0-0.23) U/kg, P=0.11; HbA1c was 6.5% (5.9%-6.8%) vs. 6.2% (5.9%-6.3%), P=0.16; and basal C-peptide was 302 (143-480) pmol/L vs. 599 (393-806) pmol/L, P=0.05. Only 37.5% of single-graft patients had a β-score ≥4 compared with 100% of double-graft patients (P=0.03). Two recipients experienced postinfusion bleeding, and two patients (13%) showed renal dysfunction in the absence of biopsy-proven rejection.

CONCLUSIONS

One infusion achieves good glycemic control and sometimes insulin independence. However, double-graft patients remain insulin-free longer, tend to have lower HbA1c, and show better graft function 24 months after transplant.

Impact of islet transplantation on diabetes complications and quality of life

Insulin represents a life-saving therapy for patients with type 1 diabetes but, despite appropriate treatment, it prevents only partially long-term diabetic complications, while generating fatal hypoglycemic episodes. Islet transplantation gained attention because of its safety, effectiveness, and minimal invasiveness; however it remains a procedure reserved for a selected group of patients. The introduction of the Edmonton Protocol in 2000, based on a newly designed steroid-free immunosuppressive protocol, revamped the course of islet transplantation. The main goal of islet transplantation remains insulin independence, although the effect of islet transplantation can be more comprehensively evaluated in terms of frequency of hypoglycemic episodes and impact on diabetic complications and quality of life. Islet transplantation was shown to have positive consequences on cardiovascular, renal, neurologic, and ocular diabetic complications. The proof of concept for cellular replacement therapy in diabetes has been established with islet transplantation, it only needs to be improved and rendered widely available.

Islet autotransplantation after extended pancreatectomy for focal benign disease of the pancreas

BACKGROUND

Extended pancreatectomy is associated with the risk of surgical diabetes. Islet autotransplantation is successful in the prevention of diabetes after pancreas resection for chronic pancreatitis (CP), with insulin independence rates of 50% at 1 year. The aim of the present study is to demonstrate the safety and efficiency of islet autotransplantation after extended left pancreatectomy for benign disease.

METHODS

Between 1992 and 2009, 25 patients underwent extended pancreatectomy and islet autotransplantation for benign disease. Of these, 15 patients were operated for focal lesions located at the neck of the pancreas (14 benign tumors and 1 traumatic pancreatic section), the remainder being CP cases. After unequivocal diagnosis of benignity, the rest of the pancreas was processed and infused into the portal vein. Metabolic results were analyzed and isolation results were compared with those obtained from patients with CP or donors with brain death (DBD).

RESULTS

There was no mortality and a low morbidity (Streptococcus mitis bacteremia in 1 patient), no portal thrombosis or pancreatic fistula occurred. Median follow-up was 90 months. Actuarial patient survival was 100% at 10 years. Actuarial insulin independence was 94% at 10 years. All patients had positive basal and stimulated C-peptide levels and normal HbA1c. Mean islet yields were 5455 IEQ/gram vs. 1457 in CP (P=0.001) and 3738 in DBD (P=0.003).

CONCLUSIONS

Islet autotransplantation after extensive pancreatic resection for benign disease is a safe and successful procedure. Islet yields after isolation, which are equivalent to the live donor situation, are significantly better than those from DBD donors.

A novel method for quantitative monitoring of transplanted islets of langerhans by positive contrast magnetic resonance imaging

The Automatic Quantitative Ultrashort Echo Time imaging (AQUTE) protocol for serial MRI allows quantitative in vivo monitoring of iron labeled pancreatic islets of Langerhans transplanted into the liver, quantifying graft implantation and persistence in a rodent model. Rats (n = 14), transplanted with iron oxide loaded cells (0-4000 islet equivalents, IEQ), were imaged using a 3D radial ultrashort echo time difference technique (dUTE) on a Siemens MAGNETOM 3T clinical scanner up to 5 months postsurgery. In vivo 3D dUTE images gave positive contrast from labeled cells, suppressing liver signal and small vessels, allowing automatic quantification. Position of labeled islet clusters was consistent over time and quantification of hyperintense pixels correlated with the number of injected IEQs (R² = 0.898, p < 0.0001), and showed persistence over time (5 months posttransplantation). Automatic quantification was superior to standard imaging and manual counting methods, due to the uniform suppressed background and high contrast, resulting in significant timesavings, reproducibility and ease of quantification. Three-dimensional coverage of the whole liver in the absence of cardiac/respiratory artifact provided further improvement over conventional imaging. This imaging protocol reliably quantifies transplanted islet mass and has high translational potential to clinical studies of transplanted pancreatic islets.

Influence of donor age on islet isolation and transplantation outcome

BACKGROUND

It has been suggested that the age of human organ donors might influence islet isolation and transplantation outcome in a negative way due to a decrease of in vivo function in islets isolated from older donors.

METHODS

We retrospectively analyzed 332 islet isolations according to donor age. We determined isolation outcome by islet yields, transplantation rates, and [beta]-cell function in vitro. Transplanted patients were divided into two groups depending on donor age (n=25 and n=31 patients for <=45- and >45-year-old donors, respectively). We assessed islet graft function by C-peptide/glucose ratio, [beta] score, secretory units of islets in transplantation index, and insulin independence rate at 1, 6, and 12 months after transplantation.

RESULTS

There was no difference in islet yields between the two groups (251,900+/-14,100 and 244,600+/-8400 islet equivalent for <=45- and >45-year-old donors, respectively). Transplantation rates and stimulation indices were similar in both groups as well. All islet graft function parameters were significantly higher at 1-month follow-up in patients who had received islets from younger donors. At 6-month follow-up after second or third injection and at 12-month follow-up, secretory units of islets in transplantation indices and C-peptide/glucose ratios were significantly higher in patients with donors aged 45 years or younger.

CONCLUSIONS

These data suggest that, despite similar outcomes of the isolation procedure, islet graft function is significantly influenced by donor age. These results may have important consequences in the definition of pancreas allocation criteria.

β-cell regeneration: the pancreatic intrinsic faculty

Type I diabetes (T1D) patients rely on cumbersome chronic injections of insulin, making the development of alternate durable treatments a priority. The ability of the pancreas to generate new β-cells has been described in experimental diabetes models and, importantly, in infants with T1D. Here we discuss recent advances in identifying the origin of new β-cells after pancreatic injury, with and without inflammation, revealing a surprising degree of cell plasticity in the mature pancreas. In particular, the inducible selective near-total destruction of β-cells in healthy adult mice uncovers the intrinsic capacity of differentiated pancreatic cells to spontaneously reprogram to produce insulin. This opens new therapeutic possibilities because it implies that β-cells can differentiate endogenously, in depleted adults, from heterologous origins.

Immune monitoring of pancreatic islet graft: towards a better understanding, detection and treatment of harmful events

IMPORTANCE OF THE FIELD

Long-term clinical outcomes of islet transplantation are hampered by rejection and recurrence of autoimmunity, which lead to a gradual decrease in islet function usually taking place over the first five years after transplantation. An accurate monitoring strategy could allow for the detection and treatment of harmful immune events, potentially resulting in higher rates of insulin-independence.

AREAS COVERED IN THIS REVIEW

This article provides a critical review of the various assays currently available for the assessment of allo- and autoimmunity both prior to and after islet transplantation. The accuracy in predicting clinical outcome is specifically addressed.

WHAT THE READER WILL GAIN

Most current tests based on the assessment of allo- and auto-immune antibody are of minimal help in clinical practice. Cell-based tests (including the assessment of cytotoxic T lymphocyte precursors, proliferation tests, enzyme-linked immunospot) have the potential to allow earlier and more accurate detection of harmful events.

TAKE HOME MESSAGE

A specific and accurate immune monitoring has the potential to significantly improve islet transplant outcomes. The development and use of such tests (favouring cell-based tests) should be promoted.

Update on transplanting beta cells for reversing type 1 diabetes

Whole pancreas has been used successfully for transplantation for more than 30 years, and islets have been used reproducibly with success for 10 years; both procedures require drugs for immunosuppression. Success is judged by discontinuation of exogenous insulin-based treatment and maintenance of normal or nearly normal hemoglobin A1c. Successful pancreas transplantation has beneficial effects on retinopathy, nephropathy, neuropathy, macrovascular disease, and quality of life. Such findings are suggested for islet transplantation, but insufficient information is available to draw firm conclusions. Because of the paucity of annual pancreas donations, research for human beta cell surrogates is essential to provide a transplantation approach to therapy for a greater number of recipients.

Islet transplantation a decade later and strategies for filling a half-full glass

Alloislet transplantation for the treatment of type 1 diabetes enjoyed highly favorable status in the first half of the last decade but declined in favor during the second half. In this Perspective, I will briefly review the literature published in this area from 2000 to 2010 for the purposes of extracting lessons we have learned, considering whether the procedure should be deemed a partial success or a partial failure, and offering several strategies to improve alloislet transplantation outcomes in the future. In the end, I hope to strike a positive note about where this procedure is going, and how it will be applied to establish insulin independence in patients with type 1 diabetes.

Liraglutide, a long-acting human glucagon-like peptide 1 analogue, improves human islet survival in culture

The culture of human islets is associated with approximately 10-20% islet loss, occasionally preventing transplantation. Preconditioning of the islets to improve postculture yields would be of immediate benefit, with the potential to increase both the number of transplanted patients and their metabolic reserve. In this study, the effect of liraglutide, a long-acting human glucagon-like peptide 1 analogue, on cultured human islets was examined. Culture with liraglutide (1 micromol/l) was associated with a preservation of islet mass (significantly more islets at 24 and 48 h, compared to control; P < or = 0.05 at 24 and 48 h) and with the presence of larger islets (P < or = 0.05 at 48 h). These observations were supported by reduced apoptosis rates after 24 h of treatment. We also demonstrated that human islet engraftment is improved in C57Bl/6-RAG(-/-) mice treated with liraglutide 200 microg/kg sc twice daily (P < or = 0.05), suggesting that liraglutide should be continued after transplantation. Overall, these data demonstrate the beneficial effect of liraglutide on cultured human islets, preserving islet mass. They support the design of clinical studies looking at the effect of liraglutide in clinical islet transplantation.

Islet alone versus islet after kidney transplantation: metabolic outcomes and islet graft survival

BACKGROUND

Isolated islet transplantation with infusions from two to three donor pancreata and Edmonton immunosuppression consistently achieves insulin independence in patients with type 1 diabetes. The success of this protocol has been attributed to a novel combination of immunosuppressive agents and avoidance of steroids; however, the outcome of islet transplantation may differ in kidney transplant recipients who are already immunosuppressed.

METHODS

We compared the metabolic outcomes and graft survival of islet transplantation in our program where nine patients underwent islet transplantation alone treated with Edmonton immunosuppression and eight patients received islet after kidney (IAK) transplants under standard kidney transplant immunosuppression often including steroids.

RESULTS

Transplants in the IAK and islet transplantation alone setting demonstrated similar islet potency (islet equivalents/unit insulin reduction) and recipients from both groups routinely gained insulin independence, functional islet mass, and duration of graft survival, however, seemed superior in the IAK group.

CONCLUSIONS

These results suggest that better islet graft function and survival may be attained using non-Edmonton rather than Edmonton immunosuppression and can include maintenance steroid therapy.

Positron emission tomography in clinical islet transplantation

The fate of islets in clinical transplantation is unclear. To elude on this positron emission tomography combined with computed tomography (PET/CT) was performed for 60 min during islet transplantation in five patients receiving six transplants. A fraction of the islets (23%) were labeled with 18F-fluorodeoxyglucose ([(18)F]FDG) and carefully mixed with unlabeled islets just prior to intraportal transplantation. The peak radioactivity concentration in the liver was found at 19 min after start of islet infusion and corresponded to only 75% of what was expected, indicating that islets are lost during the transplantation procedure. No accumulation of radioactivity was found in the lungs. A nonphysiological peak of C-peptide was found in plasma during and immediately after transplantation in all subjects. Distribution in the liver was heterogeneous with wide variations in location and concentration. Islets found in areas with concentrations of >400 IEQ/cc liver tissue varied between 1% and 32% of the graft in different subjects. No side effects attributed to the PET/CT procedure were found. Clinical outcome in all patients was comparable to that previously observed indicating that the [(18)F]FDG labeling procedure did not harm the islets. The technique has potential to be used to assess approaches to enhance islet survival and engraftment in clinical transplantation.

Who should benefit from diabetes cell therapy?

Type 1 diabetes are intrinsically unstable conditions because of the loss of both insulin secretion and glucose sensing. Guidelines to treat type 1 diabetes have become stricter since the Diabetes Control and Complications Trial (DCCT) results demonstrated the close relationship between microangiopathy and HbA1c levels, whereas the deleterious role of glucose variability on macroangiopathy has been more recently suspected. Therapeutic strategies first require the treatment of underlying organic causes of the brittleness whenever possible and, secondly, the optimization of insulin therapy using analogues, multiple injections and consideration of continuous subcutaneous insulin infusion. Alternative approaches may still be needed for the most severely affected patients, including islet transplantation. We propose islet after kidney transplantation in diabetic patients with end-stage kidney disease ineligible for double kidney-pancreas transplantation (i.e C peptide negative patients over 45 years of age or with severe macroangiopathy) if creatinine blood levels are stable below 20mg/l at least six months after kidney transplantation and steroid discontinuation. Islet transplantation alone is proposed to (1) C peptide negative diabetic patients, (2) aged 18-65 with a duration of diabetes of at least five years, (3) treated with intensive subcutaneous insulin therapy, but unable to obtain a glycated hemoglobin level below 7% without hypoglycemia and / or with brittleness and unpredictable hyper- and hypoglycemia altering quality of life, (4) with normal body weight (< 80 kg) and / or low daily insulin needs (the lower, the better), (5) with renal function close to normal (creatinine clearance above 60 ml/min with albuminuria lower than 300 mg/24 h), (6) with no desire for pregnancy in women. Currently and until more complete assessment of the 5-year overall benefit-risk ratio, islet transplantation remains a clinical research procedure. As already provided for other types of transplantation, and once recognized as a "routine" procedure, prioritization of enlisted patients for islet transplantation could be aided by the calculation of a score that should be determined by a multidisciplinary team.

Neovascularization Induced around an Artificial Device Implanted in the Abdomen by the Use of Gelatinized Fibroblast Growth Factor 2

The development of a bioartificial pancreas (BAP) with immunoisolating fashion has been gaining attention as a new method for treating diabetes. We have been proceeding with the development of a bag-type BAP that can be easily implanted and that allows for the optional injection or rejection of cells at any time. If fibrosis develops around a BAP device, then the permeability of substances transmitted through a semipermeable membrane will decrease, thereby reducing the reactivity with glucose, so it is necessary for the material of the device to have an excellent histocompatibility. Furthermore, in order to improve the efficacy of BAP treatment, it is important to maintain an environment of ample blood flow around the device. We have created a bag-type device for BAP that is 20 × 20 mm in size and comprises two layers of membranes. We have used an EVAL membrane for the outer membrane of the two layers. The EVAL membrane is a semipermeable membrane with good insulin permeability, which functions as an immunoisolation membrane. The inner membrane consists of PAU-coated HD-PE (nonwoven material processed with polyaminourethan) and it is designed to function as a scaffold for cells. We used Lewis rats to determine whether the effectiveness of fibroblast growth factor 2 (bFGF) can be improved by concomitantly using bFGF with a capacity for blood vessel regeneration as well as bFGF immersed in a sheet of gelatin. We placed the BAP in the abdominal cavity and covered it with the greater omentum. We were able to significantly increase the blood flow and the number of new blood vessels in the tissue surrounding the BAP device by using gelatinized bFGF. There were only a few instances of fibrosis as a biological reaction to the EVAL membrane, and the infiltration of inflammatory cells was mild. There were no adverse effects related to implantation of the device. We confirmed in this study that the use of an implantable BAP device and bFGF allowed for a better blood flow around the BAP device. There were only minor instances of fibrosis and inflammation reaction around the BAP, thus indicating the BAP that we are currently developing to have an excellent histocompatibility.

[Pancreatic islets transplantation in the treatment of diabetes mellitus: present and future]

Diabetes treatment with insulin does no prevent the development of secondary complications. For this reason, treatments other than conventional ones are needed, which could bring about an <<almost physiological>> metabolic regulation. This can only be done by transplanting insulin producing tissue, such as vascularised pancreas transplantation, which is an already consolidated clinical procedure these days, or by islets transplantation, which is still a procedure in the clinical research phase. This has the same metabolic objectives as the vascularised transplant, but without the risks of major abdominal surgery, since the islets are implanted in the liver with minimal surgery or using interventionist radiology by means of a catheter. A clinical trial (Edmonton Protocol) was published in the year 2000, which improved the results after islet transplantation by obtaining normoglycaemia periods of more than one year in a consecutive patient series with type 1 diabetes and without using corticoids. This protocol has been endorsed in other centre in different trials. Although the initial results were good, the progress of these patients has shown that many islets transplantations do not manage to maintain insulin-independence indefinitely.

Clinical islet transplantation in Japan

INTRODUCTION

The results of clinical islet transplantation in Japan are, here in, reported and discussed its efficacy and problems.

METHODS

Since the first islet transplantation was performed in 2004, 65 islet isolations and 34 islet transplantations to 18 type 1 diabetic patients have been performed in Japan.

RESULTS

Following islet transplantation, patients experienced decreased insulin requirements and lower hemoglobin A1C levels, and positive serum C-peptide levels. All patients achieved stabilized blood glucose levels and the disappearance of hypoglycemic unawareness. Although three patients achieved insulin independency for a limited period, persistent islet graft function was difficult to maintain. Overall islet graft survival was 86.5% at 6 months, 78.7% at 1 year, and 62.9% at 2 years after the first islet transplantation. In our institution, we carried out 23 islet isolations and six islet transplantations to four patients. Although insulin independency was not achieved, all patients showed a disappearance of hypoglycemic unawareness.

CONCLUSIONS

Using data from the Japanese Trial of Islet Transplantation, the effectiveness of islet transplantation was shown even when using the pancreata from non-heart-beating donors. Although there are a number of problems to be solved and further improvement is needed, we can state that the introduction of clinical islet transplantation offers hope for type 1 diabetic patients.

Long-term survival of nonhuman primate islets implanted in an omental pouch on a biodegradable scaffold

The aim of this study was to test whether an omental pouch can be used as an alternative site for islet implantation in diabetic monkeys. Here we report the successful engraftment of islets in diabetic cynomolgus monkeys when loaded on a synthetic biodegradable scaffold and placed in an omental pouch. One autologous and five allogeneic diabetic monkey transplants under the cover of steroid-free immune suppression (SFIS) were undertaken. Fasting blood glucose (FBG) and C-peptide (CP), exogenous insulin requirements (EIR), intravenous glucose tolerance test (IVGTT), A1C and histopathology were used to assess islet engraftment and survival. All animals achieved CP levels > 1.0 ng/mL following transplant, a 66-92% posttransplant decrease in EIR and reduced A1C. Following graft removal, CP became negative and histopathological analysis of the explanted grafts demonstrated well-granulated and well-vascularized, insulin-positive islets, surrounded by T-cell subsets and macrophages. Compared to intrahepatic allogeneic islet transplants (n = 20), there was a delayed engraftment for omental pouch recipients but similar levels of CP production were ultimately achieved, with a broad range of IEQ/kg transplanted in both sites. Our results suggest this extrahepatic transplantation site has potential as an alternative site for clinical islet cell transplantation.

Simultaneous islet and kidney transplantation in seven patients with type 1 diabetes and end-stage renal disease using a glucocorticoid-free immunosuppressive regimen with alemtuzumab induction

OBJECTIVE

The aim of this study was to evaluate the efficiency and safety of simultaneous islet and kidney transplantation in patients with type 1 diabetes and end-stage renal disease using a glucocorticoid-free immunosuppressive regimen with alemtuzumab induction.

RESEARCH DESIGN AND METHODS

Seven patients with type 1 diabetes and end-stage renal failure were transplanted with allogenic islets and kidneys procured from brain-dead donors. To prevent organ rejection, patients received alemtuzumab for induction immunosuppression, followed by sirolimus and tacrolimus. No glucocorticoids were given at any time.

RESULTS

The median duration of follow-up was 18.3 months (range 13-31). Kidney survival was 100%. Four patients became insulin independent at 1 year. The other three reduced insulin use to less than 25% of the amount required before transplantation. Serum C-peptide levels were significantly greater posttransplant in all patients, indicating continued islet function. No major procedure-related complications were observed.

CONCLUSIONS

Our results demonstrate that a steroid-free immunosuppressive regimen consisting of alemtuzumab, sirolimus, and tacrolimus is feasible for simultaneous islet and kidney transplantation. The question of whether this induction regimen is superior to more standard induction deserves large studies.

Minimization and withdrawal of steroids in pancreas and islet transplantation

For reducing the corticosteroid (CS)-related side-effects, especially cardiovascular events, CS-sparing protocols have become increasingly common in pancreas transplantation (PT). Lympho-depleting induction antibodies, such as rabbit anti-thymocyte globulin (rATG) or alemtuzumab, have been widely used in successful trials. The results of various CS-sparing protocols combining calcineurin inhibitors (CNI) and mycophenolate or sirolimus, have been mixed for rejection and survival rates. Most of the studies were uncontrolled trials of low-risk patients, therefore the grade of evidence is limited. Large-scale prospective studies with long-term follow up are necessary to assess risks and benefits of CS-sparing regimens in PT before recommending such strategies as standard practice. Islet allo-transplantation for patients with brittle type 1 diabetes mellitus, less invasive and safer procedure than PT, has been attempted since late 1980s, but diabetogenic immunosuppressants at maintenance, mainly CS and high-dose CNI, prevented satisfactory results (10% insulin-independence at 1-year post-transplant). Since 2000, CS-free and CNI-reducing protocols, including more potent induction [daclizumab, OKT3gamma1(ala-ala) anti-CD3 antibody, rATG] and maintenance (sirolimus, mycophenolate) agents, have significantly improved short-term outcomes whereas long-term are still inadequate (from 80% to 20% insulin-independence from 1- to 5-year post-transplant). Main limitations are allo- and autoimmunity, immunosuppression-related islet and systemic toxicity and transplant site unsuitability, which tolerogenic protocols and biotechnological solutions may solve.

Low risk of anti-human leukocyte antigen antibody sensitization after combined kidney and islet transplantation

Anti-human leukocyte antigen (HLA) antibody could lead to humoral rejection and a decrease in graft survival after kidney transplantation. A recent report has suggested that islet transplantation alone is associated with a high rate of sensitization. The withdrawal of the immunosuppressive therapy because of the progressive nonfunction of the islets could explain the high rate of sensitization. Because the specific risk of immunization of multiple islet infusions remains unknown, we studied the immunization rate in our cohort of multiple islet infusions transplant recipients. De novo anti-HLA antibodies were analyzed in 37 patients after islets alone (n=8), islet-after-kidney (n=13), and simultaneous islet-kidney (n=16) transplantation by solid phase assays over time. The rate of immunization was 10.8% that is comparable with the risk of immunization after kidney transplantation alone. Multiple islet infusions do not represent a specific risk for the development of anti-HLA antibodies after combined kidney-islets transplantation.

Facial transplantation and immunosuppressed patients: a new frontier in reconstructive surgery

Composite tissue transplantation in reconstructing complex facial defects has developed tremendous interest over the recent years, since the first report of partial face transplantation performed in France in 2005. However, the controversy over the ethical, immunological, and psychological issues remains. Recently, we obtained IRB approval to perform partial face transplantation at Brigham & Women's Hospital, Boston. Here we present the rationale and IRB application process of our unique approach to this highly controversial procedure, which focuses on partial face transplantation on patients currently on immunosuppressants due to previous transplanted organ. 'Patient selection criteria', selection process, technical and immunological protocols are discussed. We currently share the concern that life-long immunosuppression associated with facial transplantation may not outweigh its benefits as compared to the alternative reconstructive methods. We asked ourselves the question of which patient population would risk less and overall benefit more from undergoing face transplantation, and identified those currently on immunosuppressive therapy the most suitable candidates. Organ transplant recipients are at increased risk of malignancy, particularly skin cancer commonly located in the facial region, necessitating surgical resection and facial reconstruction. They also have to take immunosuppressants to prevent rejection of their primary transplanted organ, which will minimize the need for additional immunosuppression associated with facial allograft. Being a previous organ recipient also diminishes the difficulty of complying with the strict postoperative immunosuppressive regimen, commonly encountered by organ transplant recipients. This approach could be very beneficial for previously immunosuppressed patients and perhaps take its place in our reconstructive ladder options.

Glycemic instability in type 1 diabetic patients: Possible role of ketosis or ketoacidosis at onset of diabetes

AIMS

In type 1 diabetic patients, some have glycemic instability while others glycemic stability. We have developed criteria for evaluating glycemic instability and investigated the factors responsible.

METHODS

Glycemic instability in 52 type 1 diabetic patients was assessed by the mean amplitude of glycemic excursions (MAGE) and M-value, and clinical characteristics of good, fair and poor control groups were compared.

RESULTS

The median MAGE and M-value was 6.6mmol/L and 18.7, respectively. Then MAGE >or=6.6mmol/L and M-value >or=18.7 was defined as poor control. In the 32 patients without detectable C-peptide levels, 18 patients (56%) showed poor control. The frequency of ketosis or ketoacidosis at onset of diabetes was dramatically higher in the poor control group not only in the patients as a whole but also in those without detectable C-peptide levels.

CONCLUSIONS

A decreased level of C-peptide is a significant factor in glycemic instability. However, some patients have glycemic stability though beta-cell function is completely depleted. The presence of ketosis or ketoacidosis at onset of diabetes may be a factor in later glycemic instability, suggesting the importance of examining patients in detail at onset of diabetes for careful follow-up to prevent progression of acute and chronic complications of diabetes.

Clinical magnetic resonance imaging of pancreatic islet grafts after iron nanoparticle labeling

There is a crucial need for noninvasive assessment tools after cell transplantation. This study investigates whether a magnetic resonance imaging (MRI) strategy could be clinically applied to islet transplantation. The purest fractions of seven human islet preparations were labeled with superparamagnetic iron oxide particles (SPIO, 280 microg/mL) and transplanted into four patients with type 1 diabetes. MRI studies (T2*) were performed prior to and at various time points after transplantation. Viability and in vitro and in vivo functions of labeled islets were similar to those of control islets. All patients could stop insulin after transplantation. The first patient had diffuse hypointense images on her baseline liver MRI, typical for spontaneous high iron content, and transplant-related modifications could not be observed. The other three patients had normal intensity on pretransplant images, and iron-loaded islets could be identified after transplantation as hypointense spots within the liver. In one of them, i.v. iron therapy prevented subsequent visualization of the spots because of diffuse hypointense liver background. Altogether, this study demonstrates the feasibility and safety of MRI-based islet graft monitoring in clinical practice. Iron overload (spontaneous or induced) represents the major obstacle to the technique.

Allogeneic islet transplantation

Significant progress has been made in the field of beta-cell replacement therapies by islet transplantation in patients with unstable Type 1 diabetes mellitus (T1DM). Recent clinical trials have shown that islet transplantation can reproducibly lead to insulin independence when adequate islet numbers are implanted. Benefits include improvement of glycemic control, prevention of severe hypoglycemia and amelioration of quality of life. Numerous challenges still limit this therapeutic option from becoming the treatment of choice for T1DM. The limitations are primarily associated with the low islet yield of human pancreas isolations and the need for chronic immunosuppressive therapies. Herein the authors present an overview of the historical progress of islet transplantation and outline the recent advances of the field. Cellular therapies offer the potential for a cure for patients with T1DM. The progress in beta-cell replacement treatment by islet transplantation as well as those of emerging immune interventions for the restoration of self tolerance justify great optimism for years to come.

Resolution of severe atopic dermatitis after tacrolimus withdrawal

Tacrolimus is an immunosuppressive agent used in solid organ and islet transplantation. Its topical form has shown benefit in the treatment of inflammatory skin conditions. Although tacrolimus has a wide spectrum of side effects, dermatological complications related to systemic tacrolimus therapy are limited in the literature. Atopic dermatitis (AD) is a chronic pruritic cutaneous condition that usually begins in infancy and is characterized by an increased Th2 response. We report the case of a patient with type 1 diabetes mellitus (T1DM) and history of AD latent for 10 years who developed severe dermatitis and alopecia 5 months after undergoing allogeneic islet transplantation and initiating a steroid-free immunosuppressive regimen with sirolimus and tacrolimus maintenance. After exclusion of other possible causes for the progression and exacerbation of the clinical presentation of AD, discontinuation of tacrolimus and introduction of mycophenolate mofetil resulted in full remission of the symptoms. The beneficial effects of tacrolimus withdrawal suggest a cause-effect relationship between this adverse event and the utilization of the drug. Islet graft function remained stable after modification of the therapeutic regimen (stable glycemic control and unchanged C-peptide).

Induction of long-term liver allograft survival by delayed immunosuppression is dependent on interleukin-10

This study aims to investigate the potential role of endogenous interleukin (IL)-10 in long-term liver allograft survival induced by delayed immunosuppression (FK506 days 2-7). Liver transplantation was performed by using Dark Agouti and Lewis rats as donors and recipients, respectively. The delayed immunosuppression protocol induced indefinite allograft survival. A transient upregulation of plasma IL-10 levels was detected in the nontreatment and FK506 treatment groups. Macrophages were found to be one of the major sources of IL-10 produced from the liver allografts. Administration of IL-10-neutralizing antibody shortened the long-term isograft survival and FK506-induced indefinite allograft survival, particularly in the FK506 group. Damaged liver graft histology and increase of plasma alanine aminotransferase levels were detected in the groups with IL-10 antibody treatment. In an ex vivo setting, IL-10 recombinant protein augmented the expression of Foxp3, downregulated the expression of IL-2 and interferon gamma, and induced the generation of CD4(+)CD25(+)Foxp3(+) and CD8(+)CD25(+)Foxp3(+) cells, but this effect was blocked by the administration of IL-10 antibody. Finally, administration of IL-10 recombinant protein after the decline of endogenous IL-10 levels improved allograft survival, and a 100% long-term allograft survival was achieved by the combination of IL-10 with low-dose FK506. In conclusion, the delayed immunosuppression could induce long-term liver allograft survival in the presence of endogenous IL-10 produced by the tissue macrophages. Supplementary exogenous IL-10 administration combined with low-dose immunosuppressive drug may be a useful strategy to induce long-term liver allograft survival.

Monitoring of the islet graft

The Edmonton trials have brought about a marked improvement in the short-term rate of success of islet transplantation with rates of insulin-independence of 80% at 1-year being reported by several institutions worldwide. Unfortunately, this rate consistently decreases to 10-15% by 5 years post-transplantation. Several mechanisms have been proposed to explain this apparent 'islet exhaustion', but are difficult to pinpoint in a given patient. Understanding the reasons for islet graft exhaustion and its kinetics is a prerequisite for the improvement of islet transplantation outcome. In this regard, efficient monitoring tools for the islet graft have been conspicuously lacking and are required to detect islet damage and diagnose its mechanisms in a timely fashion, so as to initiate salvage therapy such as antirejection treatment. Tools for the monitoring of the islet graft include follow-up of metabolic function but mostly indicate dysfunction when it is too late to take action. Progress is likely to arise in the fields of immune monitoring, molecular monitoring and islet imaging, notably thanks to magnetic resonance (MR) or positron emission tomography (PET) technologies.