Islet transplantation is associated with an improvement of cardiovascular function in type 1 diabetic kidney transplant patients

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.

Cibinetide Protects Isolated Human Islets in a Stressful Environment and Improves Engraftment in the Perspective of Intra Portal Islet Transplantation

During intra-portal pancreatic islet transplantation (PITx), innate immune reactions such as the instant blood mediated inflammatory reaction (IBMIR) cause an immediate loss of islets. The non-hematopoietic erythropoietin analogue cibinetide has previously shown islet-protective effects in mouse PITx. Herein, we aimed to confirm cibinetide's efficacy on human islets, and to characterize its effect on IBMIR. We cultured human islets with pro-inflammatory cytokines for 18 hours with or without cibinetide. ATP content and caspase 3/7 activity were measured. Dynamic glucose perfusion assay was used to evaluate islet function. To evaluate cibinetides effect on IBMIR, human islets were incubated in heparinized polyvinyl chloride tubing system with ABO compatible blood and rotated for 60 minutes to mimic the portal vein system. Moreover, human islets were transplanted into athymic mice livers via the portal vein with or without perioperative cibinetide treatment. The mice were sacrificed six days following transplantation and the livers were analyzed for human insulin and serum for human C-peptide levels. Histological examination of recipient livers to evaluate islet graft infiltration by CD11b⁺ cells was performed. Our results show that cibinetide maintained human islet ATP levels and reduced the caspase 3/7 activity during culture with pro-inflammatory cytokines and improved their insulin secreting capacity. In the PVC loop system, administration of cibinetide reduced the IBMIR-induced platelet consumption. In human islet to athymic mice PITx, cibinetide treatment showed an increased amount of human insulin in the livers and higher serum human C-peptide, while histological examination of the livers showed reduced infiltration of pro-inflammatory CD11b⁺ cells around islets grafts compared to the controls. In summary, Cibinetide protected isolated human islets in a pro-inflammatory milieu and reduced IBMIR related platelet consumption. It improved engraftment of human islets in athymic mice. The study confirms that cibinetide is a promising agent to be used in clinical PITx.

Chances and risks of sodium-glucose cotransporter 2 inhibitors in solid organ transplantation: A review of literatures

Solid organ transplantation offers life-saving treatment for patients with end-organ dysfunction. Patient survival and quality of life have improved over the past few decades as a result of pharmacological development, expansion of the donor pool, technological advances and standardization of practices related to transplantation. Still, transplantation is associated with cardiovascular complications, of which post-transplant diabetes mellitus (PTDM) is one of the most important. PTDM increases mortality, which is best documented in patients who have received kidney and heart transplants. PTDM results from traditional risk factors seen in patients with type 2 diabetes mellitus, but also from specific post-transplant risk factors such as metabolic side effects of immunosuppressive drugs, post-transplant viral infections and hypomagnesemia. Oral hypoglycaemic agents are the first choice for the treatment of type 2 diabetes mellitus in non-transplanted patients. However, the evidence on the safety and efficacy of oral hypoglycaemic agents in transplant recipients is limited. The favourable risk/benefit ratio, which is suggested by large-scale and long-term studies on new glucose-lowering drug classes such as glucagon-like peptide 1 receptor agonists and sodium-glucose cotransporter 2 inhibitors, makes studies warranted to assess the potential role of these agents in the management of PTDM.

Immunological Monitoring in Beta Cell Replacement: Towards a Pathophysiology-Guided Implementation of Biomarkers

PURPOSE OF REVIEW

Grafted beta cells are lost because of recurrence of T1D and/or allograft rejection, two conditions diagnosed with pancreas graft biopsy, which is invasive and impossible in case of islet transplantation. This review synthetizes the current pathophysiological knowledge and discusses the interest of available immune biomarkers.

RECENT FINDINGS

Despite the central role of auto-(recurrence of T1D) and allo-(T-cell mediated rejection) immune cellular responses, the latter are not directly monitored in routine. In striking contrast, there have been undisputable progresses in monitoring of auto and alloantibodies. Except for pancreas recipients in whom anti-donor HLA antibodies can be directly responsible for antibody-mediated rejection, autoantibodies (and alloantibodies in islet recipients) have no direct pathogenic effect. However, their fluctuation offers a surrogate marker for the activation status of T cells (because antibody generation depends on T cells). This illustrates the necessity to understand the pathophysiology when interpreting a biomarker and selecting the appropriate treatment.

Linagliptin plus insulin for hyperglycemia immediately after renal transplantation: A comparative study

AIMS

Post-renal-transplanted patients frequently present hyperglycemia immediately after the procedure. The goal of this work was to evaluate the effect of linagliptin + insulin in post-renal-transplanted patients with hyperglycemia.

METHODS

Retrospective comparative study in post-renal transplanted patients with hyperglycemia after transplantation who were treated with linagliptin 5 mg daily plus insulin vs insulin alone for 5 days after renal transplantation with hyperglycemia. Main outcomes were glucose levels, insulin dose and severity of hypoglycemia.

RESULTS

There were 14 patients treated with linagliptin + insulin and 14 patients treated only with insulin. Glucose levels and insulin doses were lower in the linagliptin + insulin group in comparison with the insulin alone group, 131.0 ± 15.1 vs 191.1 ± 22.5 mg/dl (7.27 ± 0.84 vs 10.61 ± 1.25 mmol/l) and 37.5 ± 6.3 vs 24.2 ± 6.6 U, respectively (p < 0.05). Hypoglycemia was less severe in the linagliptin + insulin group, 65.1 ± 2.2 vs 54.2 ± 3.3 mg/dl (3.61 ± 0.12 vs 3.00 ± 3.3 ± 0.18 mmol/l), p 0.036.

CONCLUSIONS

The combination of linagliptin + insulin provided better glycemic control with a lower insulin dose and less severe hypoglycemia in comparison to insulin alone in patients with hyperglycemia immediately after renal transplantation.

Insulin-mimetic effects of short-term rapamycin in type 1 diabetic patients prior to islet transplantation

BACKGROUND

The immunosuppressive drug rapamycin may influence insulin sensitivity in insulin-responsive tissues.

AIMS

This study aimed at evaluating the effectiveness of rapamycin pre-treatment before pancreatic islet allotransplantation (ITx) in patients with type 1 diabetes mellitus (T1DM).

METHODS

Forty-one T1DM patients were studied. Thirteen patients with poor glycemic control underwent a short-term rapamycin treatment before ITx (Group 1), and they were compared to 28 patients undergoing ITx without rapamycin pre-treatment (Group 2). Outcomes were daily insulin requirement (DIR), fasting blood glucose, HbA1c, C-peptide and the SUITO index of beta-cell function. A subgroup of patients pre-treated with rapamycin before ITx underwent euglycemic hyperinsulinemic clamp with [6,6-²H₂] glucose before and after ITx to evaluate insulin sensitivity.

RESULTS

We found a significant reduction in DIR after rapamycin pre-treatment (- 8 ± 6 U/day, mean ± SD, p < 0.001) and 1 year after ITx. DIR reduction 1 year after ITx was greater in Group 1 as compared to Group 2 (- 37 ± 15 vs. - 19 ± 13 U/day, p = 0.005) and remained significant after adjusting for gender, age, glucose and baseline HbA1c (beta = 18.2 ± 5.9, p = 0.006). Fasting glucose and HbA1c significantly decreased 1 year after ITx in Group 1 (HbA1c: - 2.1 ± 1.4%, p = 0.002), while fasting C-peptide (+0.5 ± 0.3 nmol/l, p = 0.002) and SUITO index increased (+57.4 ± 39.7, p = 0.016), without differences between the two groups. Hepatic glucose production decreased after rapamycin pre-treatment (- 1.1 ± 1.1 mg/kg/min, p = 0.04) and after ITx (- 1.6 ± 0.6 mg/kg/min, p = 0.015), while no changes in peripheral glucose disposal were observed.

CONCLUSIONS

Rapamycin pre-treatment before ITx succeeds in reducing insulin requirement, enhancing hepatic insulin sensitivity. This treatment may improve short-term ITx outcomes, possibly in selected patients with T1DM complicated by insulin resistance.

CLINICAL TRIAL

Clinicaltrials.gov NCT01060605; NCT00014911.

Long-term Effect of Islet Transplantation on Glycemic Variability

Islet transplantation has been reported to restore normoglycemia and the overall metabolic control in type 1 diabetes mellitus (DM). In the most experienced centers, islet transplantation clinical outcome is similar to that of the whole pancreas transplantation. Long-term islet transplantation function remains a very interesting matter worth discussing. A progressive islet function decrease was reported, probably due to islet exhaustion. In 5 islet-transplanted patients with at least 3-yr follow-up and still insulin independent, their glycemic control was characterized by a blinded retrospective continuous glucose monitoring system (CGMS). Islet transplantation restored glycemic control and glucose variability. Data were compared with patients in the waiting list. All the parameters of glycemic variability tested had improved significantly in patients who had islet transplantation compared with those patients who were on the waiting list. In conclusion, islet transplantation is able to maintain a proper glucose control and normalize glycemic variability in selected patients. A blinded retrospective CGMS is a useful method to characterize glucose homeostasis deeply in vivo in islet-transplanted patients.

Allo- and auto-percutaneous intra-portal pancreatic islet transplantation (PIPIT) for diabetes cure and prevention: the role of imaging and interventional radiology

Although the life expectancy of patients with type 1 diabetes mellitus (T1DM) has improved since the introduction of insulin therapy, the acute life-threatening and long-term complications from diabetes mellitus are significant causes of both mortality and morbidity. Percutaneous intra-portal pancreatic islet transplantation (PIPIT) is a minimally invasive, repeatable procedure which allows a β-cell replacement therapy through a liver islet engraftment, leading to insulin release and glycaemic control restoration in patients with diabetes. Allo-PIPIT, in which isolated and purified islets from cadaveric donor are used, does not require major surgery, and is potentially less expensive for the recipient. In case of long-term T1DM, islet-after-kidney (IAK) transplantation can simultaneously cure diabetes and chronic renal failure, while islet-transplant-alone (ITA) is performed in brittle, short-term T1DM, based on the infusion of an adequate islet mass and on a steroid-free immunosuppressive regimen according to the Edmonton protocol. Results of the Collaborative Islet Transplant Registry (CITR) demonstrate that allo-PIPIT reduces episodes of hypoglycemia and diabetic complications, and improves quality of life of diabetic patients. Auto-PIPIT, in which the own patient's islets are used, has been investigated as a preventive treatment for pancreatogenic diabetes in patients who undergo extensive pancreatectomy for malignant and non-malignant disease. This Review outlines the role of imaging and interventional radiology in allo- and auto-PIPIT.

Effect of post-transplant glycemic control on long-term clinical outcomes in kidney transplant recipients with diabetic nephropathy: A multicenter cohort study in Korea

PURPOSE

Diabetic nephropathy is the leading cause of end stage renal disease. The number of kidney transplantation (KT) due to diabetic nephropathy is increasing and there is debate on glycemic control after KT. In this study, we used a multi-center database to determine the relationship between post-transplant glycemic control and the outcomes of KT in patients with diabetic nephropathy.

METHODS

We conducted a retrospective chart review of kidney transplant recipients (KTRs) with diabetic nephropathy from three tertiary hospitals to analyze the association between post-transplant glycemic control and the clinical outcomes of graft failure, including patient death and biopsy-proven acute rejection (BPAR). We assessed time-averaged glucose level and hemoglobin A1c (HbA1c) for 36 months after KT.

RESULTS

Among 3,538 KTRs, a total of 476 patients received kidney transplantation because of diabetic nephropathy. Mean time-averaged glucose and HbA1c levels were 147 ± 46 mg/dl and 7.7 ± 1.5%, respectively. Patients with diabetic nephropathy had poor graft and patient survival rate compared with non-diabetic nephropathy. Among KTRs with diabetic nephropathy, the highest quartile of time-averaged glucose was related to poor graft outcomes and the 3rd quartile of time-averaged HbA1c was associated with significantly better graft outcomes than the 1st, 2nd or 4th quartiles. There were no significant differences in the risk of BPAR across the 4 quartiles of glucose and HbA1c.

CONCLUSIONS

Strict glycemic control before KT might not be related to successful outcomes but poor glycemic control after KT is associated with poor graft outcomes. There was no significant relationship between pre- or post-transplant glycemic control and BPAR.

[Transplantation strategy in type 1 diabetic patients]

Beta cell replacement by pancreas or Langerhans islets transplantation is the only way to restore glucose homeostasis in type 1 diabetic patients. The counterpart is the need for long-term immunosuppression. These transplantations are therefore mainly indicated for patients candidates for kidney transplantation and for patients with poor quality of life due to unstable diabetes with life-threatening hypoglycemic events. Both beta cell replacement techniques have different benefits and risks and should be adapted to each type 1 diabetic patient. The transplant strategy must be personalized according to parameters assessed in the pre-transplant period, validated by a multidisciplinary team and reassessed regularly until transplantation.

Selection of Implantation Sites for Transplantation of Encapsulated Pancreatic Islets

Pancreatic islet transplantation has been validated as a valuable therapy for type 1 diabetes mellitus patients with exhausted insulin treatment. However, this therapy remains limited by the shortage of donor and the requirement of lifelong immunosuppression. Islet encapsulation, as an available bioartificial pancreas (BAP), represents a promising approach to enable protecting islet grafts without or with minimal immunosuppression and possibly expanding the donor pool. To develop a clinically implantable BAP, some key aspects need to be taken into account: encapsulation material, capsule design, and implant site. Among them, the implant site exerts an important influence on the engraftment, stability, and biocompatibility of implanted BAP. Currently, an optimal site for encapsulated islet transplantation may include sufficient capacity to host large graft volumes, portal drainage, ease of access using safe and reproducible procedure, adequate blood/oxygen supply, minimal immune/inflammatory reaction, pliable for noninvasive imaging and biopsy, and potential of local microenvironment manipulation or bioengineering. Varying degrees of success have been confirmed with the utilization of liver or extrahepatic sites in an experimental or preclinical setting. However, the ideal implant site remains to be further engineered or selected for the widespread application of encapsulated islet transplantation.

Clinical pancreatic islet transplantation

Clinical pancreatic islet transplantation can be considered one of the safest and least invasive transplant procedures. Remarkable progress has occurred in both the technical aspects of islet cell processing and the outcomes of clinical islet transplantation. With >1,500 patients treated since 2000, this therapeutic strategy has moved from a curiosity to a realistic treatment option for selected patients with type 1 diabetes mellitus (that is, those with hypoglycaemia unawareness, severe hypoglycaemic episodes and glycaemic lability). This Review outlines the techniques required for human islet isolation, in vitro culture before the transplant and clinical islet transplantation, and discusses indications, optimization of recipient immunosuppression and management of adjunctive immunomodulatory and anti-inflammatory strategies. The potential risks, long-term outcomes and advances in treatment after the transplant are also discussed to further move this treatment towards becoming a more widely available option for patients with type 1 diabetes mellitus and eventually a potential cure.

Progress in islet transplantation in patients with type 1 diabetes mellitus

More than 500 patients with type 1 diabetes mellitus have now received islet transplants at over 50 institutions worldwide in the past 5 years. Rates of insulin independence at 1 year with current protocols are impressive. However, inexorable decay of islet function over time indicates that there are many opportunities for improvement. Improved control of glycosylated hemoglobin and reduced risk of recurrent hypoglycemia are seen as important benefits of islet transplantation, irrespective of the status regarding insulin independence. For the use of islet transplantation to expand it is essential that the donor-to-recipient ratio be reliably reduced to 1 : 1. Enormous opportunities lie ahead for the development of successful living donor islet transplantation, single donor protocols, improved engraftment, islet proliferation in vitro and in the recipient, alternative islet sources, and novel tolerizing drugs. With these emerging opportunities, islet transplantation may expand to include more patients with type 1 diabetes, including children, and will not be restricted to the most unstable forms of the disease, as it is today.

Regenerative Therapy of Type 1 Diabetes Mellitus: From Pancreatic Islet Transplantation to Mesenchymal Stem Cells

Type 1 diabetes is an autoimmune disease resulting in the permanent destruction of pancreatic islets. Islet transplantation to portal vein provides an approach to compensate for loss of insulin producing cells. Clinical trials demonstrated that even partial islet graft function reduces severe hypoglycemic events in patients. However, therapeutic impact is restrained due to shortage of pancreas organ donors and instant inflammation occurring in the hepatic environment of the graft. We summarize on what is known about regenerative therapy in type 1 diabetes focusing on pancreatic islet transplantation and new avenues of cell substitution. Metabolic pathways and energy production of transplanted cells are required to be balanced and protection from inflammation in their intravascular bed is desired. Mesenchymal stem cells (MSCs) have anti-inflammatory features, and so they are interesting as a therapy for type 1 diabetes. Recently, they were reported to reduce hyperglycemia in diabetic rodents, and they were even discussed as being turned into endodermal or pancreatic progenitor cells. MSCs are recognized to meet the demand of an individual therapy not raising the concerns of embryonic or induced pluripotent stem cells for therapy.

Serum Cytokines as Biomarkers in Islet Cell Transplantation for Type 1 Diabetes

Background

Islet cell transplantation holds a potential cure for type 1 diabetes, but many islet recipients do not reach long-lasting insulin independence. In this exploratory study, we investigated whether serum cytokines, chemokines and adipokines are associated with the clinical outcome of islet transplantation.

Methods

Thirteen islet transplant patients were selected on basis of good graft function (reaching insulin independence) or insufficient engraftment (insulin requiring) from our cohort receiving standardized grafts and immune suppressive therapy. Patients reaching insulin independence were divided in those with continued (>12 months) versus transient (<6 months) insulin independence. A panel of 94 proteins including cytokines and adipokines was measured in sera taken before and at one year after transplantation using a validated multiplex immunoassay platform.

Results

Ninety serum proteins were detectable in concentrations varying markedly among patients at either time point. Thirteen markers changed after transplantation, while another seven markers changed in a clinical subpopulation. All other markers remained unaffected after transplantation under generalized immunosuppression. Patterns of cytokines could distinguish good graft function from insufficient function including IFN-α, LIF, SCF and IL-1RII before and after transplantation, by IL-16, CCL3, BDNF and M-CSF only before and by IL-22, IL-33, KIM-1, S100A12 and sCD14 after transplantation. Three other proteins (Leptin, Cathepsin L and S100A12) associated with loss of temporary graft function before or after transplantation.

Conclusions

Distinct cytokine signatures could be identified in serum that predict or associate with clinical outcome. These serum markers may help guiding patient selection and choice of immunotherapy, or act as novel drug targets in islet transplantation.

Differentiation of human pluripotent stem cells into β-cells: Potential and challenges

Human embryonic stem cells (hESCs) and induced pluripotent stem cells (iPSCs) hold great potential as the basis for cell-based therapies of degenerative diseases, including diabetes. Current insulin-based therapies for diabetes do not prevent hyperglycaemia or the associated long-term organ damage. While transplantation of pancreatic islets can achieve insulin independence and improved glycemic control, it is limited by donor tissue scarcity, challenges of purifying islets from the pancreas, and the need for immunosuppression to prevent rejection of transplants. Large-scale production of β-cells from stem cells is a promising alternative. Recent years have seen considerable progress in the optimization of in vitro differentiation protocols to direct hESCs/iPSCs into mature insulin-secreting β-cells and clinical trials are now under way to test the safety and efficiency of hESC-derived pancreatic progenitor cells in patients with type 1 diabetes. Here, we discuss key milestones leading up to these trials in addition to recent developments and challenges for hESC/iPSC-based diabetes therapies and disease modeling.

Using the cost–effectiveness of allogeneic islet transplantation to inform induced pluripotent stem cell-derived β-cell therapy reimbursement

Aims: In the present study a cost–effectiveness analysis of allogeneic islet transplantation was performed and the financial feasibility of a human induced pluripotent stem cell-derived β-cell therapy was explored. Methods: Previously published cost and health benefit data for islet transplantation were utilized to perform the cost–effectiveness and sensitivity analyses. Results & conclusion: It was determined that, over a 9-year time horizon, islet transplantation would become cost saving and ‘dominate’ the comparator. Over a 20-year time horizon, islet transplantation would incur significant cost savings over the comparator (GB£59,000). Finally, assuming a similar cost of goods to islet transplantation and a lack of requirement for immunosuppression, a human induced pluripotent stem cell-derived β-cell therapy would dominate the comparator over an 8-year time horizon.

Clinical results of islet transplantation

Islet transplantation is considered an advanced therapy in the treatment of type-1 diabetes, with a progressive improvement of clinical results as seen in the Collaborative Islet Transplant Registry (CITR) report. It is an accepted method for the stabilization of frequent hypoglycemia, or severe glycemic lability, in patients with hypoglycemic unawareness, poor diabetic control, or a resistance to intensive insulin-based therapies. Worldwide data confirm a positive trend in this field, with the integrated management of pivotal factors: adequate islet mass, immunosuppressive protocols, additional anti-inflammatory therapy, and pre-transplant allo-immunity assessment. Insulin independence has been observed in several clinical trials with different rate, ranging 100-65% of patients; the maintenance of this condition during the follow-up progressively decreased, actually arranged on 44% 3 years after the last infusion, according to data reported from the CITR. Successful duration is progressively increasing, with ≥13 years being the longest reported insulin-free condition on record. The immediate results of functioning islet transplantation are an improvement in hypoglycemic awareness and a reduction in the glycated hemoglobin level. Furthermore, many studies have shown its influence on the chronic complications of diabetes, such as peripheral neuropathy, retinopathy, and macroangiopathy. Pre-transplant nephropathy remains an exclusion criterion as immunosuppressive therapy can exacerbate kidney-function deterioration. The problems linked to immunosuppression following islet transplantation for the treatment of type-1 diabetes need to be considered in order to achieve the correct risk/benefit ratio for each patient.

Clinical application of microencapsulated islets: actual prospectives on progress and challenges

After 25 years of intense pre-clinical work on microencapsulated intraperitoneal islet grafts into non-immunosuppressed diabetic recipients, the application of this procedure to patients with type 1 diabetes mellitus has been a significant step forward. This result, achieved in a few centers worldwide, underlies the safety of biopolymers used for microencapsulation. Without this advance, no permission for human application of microcapsules would have ever been obtained after years of purification technologies applied to the raw alginates. To improve safety of the encapsulated islet graft system, renewed efforts on the capsules' bioengineering, as well as on insulin-producing cells within the capsular membranes, are in progress. It is hoped that advances in these two critical aspects of the cell encapsulation technology will result in wider human application of this system.

TIM4 Regulates the Anti-Islet Th2 Alloimmune Response

The role of the novel costimulatory molecule TIM4 in anti-islet response is unknown. We explored TIM4 expression and targeting in Th1 (BALB/c islets into C57BL/6 mice) and Th2 (BALB/c islets into Tbet(-/-) C57BL/6 mice) models of anti-islet alloimmune response and in a model of anti-islet autoimmune response (diabetes onset in NOD mice). The targeting of TIM4, using the monoclonal antibody RMT4-53, promotes islet graft survival in a Th1 model, with 30% of the graft surviving in the long term; islet graft protection appears to be mediated by a Th1 to Th2 skewing of the immune response. Differently, in the Th2 model, TIM4 targeting precipitates graft rejection by further enhancing the Th2 response. The effect of anti-TIM4 treatment in preventing autoimmune diabetes was marginal with only minor Th1 to Th2 skewing. B-Cell depletion abolished the effect of TIM4 targeting. TIM4 is expressed on human B-cells and is upregulated in diabetic and islet-transplanted patients. Our data suggest a model in which TIM4 targeting promotes Th2 response over Th1 via B-cells. The targeting of TIM4 could become a component of an immunoregulatory protocol in clinical islet transplantation, aiming at redirecting the immune system toward a Th2 response.

Islet transplantation in type 1 diabetes: hype, hope and reality - a clinician's perspective

The β-cell replacement by islet transplantation is an attractive approach for normalizing blood glucose without hypoglycaemia in patient with type 1 diabetes mellitus (T1D). A pioneer study by the Edmonton group more than a decade ago showed that alloislet transplantation may result in insulin independence for at least 1 year after transplantation. This breakthrough excited researchers, physicians and patients, who felt that the ultimate goal of cure for T1D was at hand. Longer follow-up of patients who underwent islet transplantation showed less favourable results, with only approximately 10% of the patients remaining insulin-free 5 years after transplantation. In the last few years, progress has been made, and the success rate of islet transplantation has steadily increased. Important hurdles, however, related to limited tissue supply and need for life-long immunosuppressive drugs have yet to be overcome. Herein, we review recent achievements in islet transplantation and the challenges that still need to be addressed before this procedure can become a standard therapy for T1D.

Islet transplantation stabilizes hemostatic abnormalities and cerebral metabolism in individuals with type 1 diabetes

OBJECTIVE Islets after kidney transplantation have been shown to positively affect the quality of life of individuals with type 1 diabetes (T1D) by reducing the burden of diabetes complications, but fewer data are available for islet transplantation alone (ITA). The aim of this study was to assess whether ITA has a positive impact on hemostatic and cerebral abnormalities in individuals with T1D. RESEARCH DESIGN AND METHODS Prothrombotic factors, platelet function/ultrastructure, and cerebral morphology, metabolism, and function have been investigated over a 15-month follow-up period using ELISA/electron microscopy and magnetic resonance imaging, nuclear magnetic resonance spectroscopy, and neuropsychological evaluation (Profile of Mood States test and paced auditory serial addition test) in 22 individuals with T1D who underwent ITA (n = 12) or remained on the waiting list (n = 10). Patients were homogeneous with regard to metabolic criteria, hemostatic parameters, and cerebral morphology/metabolism/function at the time of enrollment on the waiting list. RESULTS At the 15-month follow-up, the group undergoing ITA, but not individuals with T1D who remained on the waiting list, showed 1) improved glucose metabolism; 2) near-normal platelet activation and prothrombotic factor levels; 3) near-normal cerebral metabolism and function; and 4) a near-normal neuropsychological test. CONCLUSIONS ITA, despite immunosuppressive therapy, is associated with a near-normalization of hemostatic and cerebral abnormalities.

Reduction in carotid intima-media thickness after pancreatic islet transplantation in patients with type 1 diabetes

OBJECTIVE

Determine the impact of islet transplantation on carotid intima-media thickness (CIMT), a marker for atherosclerosis, in type 1 diabetes without kidney disease.

RESEARCH DESIGN AND METHODS

Consecutive case series of 15 adults (mean age [SD], 49 years [10 years]; 87% female) with type 1 diabetes for ≥5 years (mean duration [SD], 30 years [12 years]; mean HbA(1c) [SD], 7.2% [0.9%]), without kidney disease, presenting with severe hypoglycemic unawareness to undergo allogeneic pancreatic islet transplant(s) (one to three each) in a phase 1/2 and 3 clinical trial. Current follow-up ranges from 1 to 5 years (2005-2011). CIMT of the common and internal carotid arteries was measured before and every 12-16 months after the first transplant (two to six CIMTs each) by one ultrasonographer and one blinded reader. CIMT was analyzed as change from baseline to 12- and 50-month follow-up; a combined CIMT score was calculated as the sum of the standardized IMT scores (SD units [SDs]) of both arteries.

RESULTS

All patients achieved insulin independence after one to three transplants. CIMT decreased at 12 months (n = 15) for the common carotid (-0.058 mm; P = 0.006) and combined score (-1.28 SDs; P = 0.004). In those with 50-month follow-up (n = 7), the decrease in the combined score continued from 12 (-1.59 SDs; P = 0.04) to 50 months (-0.77 SDs; P = 0.04). During follow-up, the decreasing slope of change in CIMT was associated with decreasing slopes of change in HbA(1c), lipoproteins, and cardiovascular/inflammatory markers.

CONCLUSIONS

Islet transplantation may ameliorate diabetes-related atherosclerosis through improved glycemic control consequent to restoring endogenous insulin secretion, and optimal lipid management posttransplant also contributes.

Islet transplantation in type 1 diabetes: ongoing challenges, refined procedures, and long-term outcome

Remarkable progress has been made in islet transplantation over a span of 40 years. Once just an experimental curiosity in mice, this therapy has moved forward, and can now provide robust therapy for highly selected patients with type 1 diabetes (T1D), refractory to stabilization by other means. This progress could not have occurred without extensive dynamic international collaboration. Currently, 1,085 patients have undergone islet transplantation at 40 international sites since the Edmonton Protocol was reported in 2000 (752 allografts, 333 autografts), according to the Collaborative Islet Transplant Registry. The long-term results of islet transplantation in selected centers now match registry data of pancreas-alone transplantation, with 6 sites reporting five-year insulin independence rates ≥50%. Islet transplantation has been criticized for the use of multiple donor pancreas organs, but progress has also occurred in single-donor success, with 10 sites reporting increased single-donor engraftment. The next wave of innovative clinical trial interventions will address instant blood-mediated inflammatory reaction (IBMIR), apoptosis, and inflammation, and will translate into further marked improvements in single-donor success. Effective control of auto- and alloimmunity is the key to long-term islet function, and high-resolution cellular and antibody-based assays will add considerable precision to this process. Advances in immunosuppression, with new antibody-based targeting of costimulatory blockade and other T-B cellular signaling, will have further profound impact on the safety record of immunotherapy. Clinical trials will move forward shortly to test out new human stem cell derived islets, and in parallel trials will move forward, testing pig islets for compatibility in patients. Induction of immunological tolerance to self-islet antigens and to allografts is a difficult challenge, but potentially within our grasp.

Vascular access in patients receiving hemodialysis in Libya

PURPOSE

A native arteriovenous fistula (AVF) represents the optimal form of Vascular Access (VA) for patients receiving hemodialysis (HD). In Libya there are several barriers to AVF creation including lack of adequate preparation for dialysis and surgical services. We aimed to conduct the first comprehensive study of VA utilisation in HD patients in Libya.

METHODS

A prospective observational study included all adult patients receiving HD treatment in 25 HD facilities in Libya from May 2009 to Nov 2011. Researchers gathered data regarding VA through interviews with staff and patients as well as medical records. Patients with definitive VA were re-interviewed after 1 year.

RESULTS

At baseline the majority of patients (91.9%; n=1573) were using permanent VA in the form of AVF or arteriovenous graft. Patients with permanent VA were more likely to be male and less likely to be diabetic than those with CVCs. Most patients had commenced HD using a temporary CVC (91.8%). VA-related complications were: thrombosis (46.7%), aneurysm (22.6%), infection (11.5%) and haemorrhage (10.2%). Incident VA thrombosis was reported by 14.7% in 1 year. Independent risk factors for incident thrombosis were female gender and diabetes. Hospitalisation for VA related complications was reported by 31.4%.

CONCLUSIONS

Few patients in Libya initiate HD with definitive VA, but most achieve it thereafter. Improved dialysis preparation and increased provision of surgical services are required to increase the proportion of patients initiating HD with definitive VA and should be a priority in rebuilding health services in Libya after the recent conflict.

Regenerative therapies for diabetic microangiopathy

Hyperglycaemia occurring in diabetes is responsible for accelerated arterial remodeling and atherosclerosis, affecting the macro- and the microcirculatory system. Vessel injury is mainly related to deregulation of glucose homeostasis and insulin/insulin-precursors production, generation of advanced glycation end-products, reduction in nitric oxide synthesis, and oxidative and reductive stress. It occurs both at extracellular level with increased calcium and matrix proteins deposition and at intracellular level, with abnormalities of intracellular pathways and increased cell death. Peripheral arterial disease, coronary heart disease, and ischemic stroke are the main causes of morbidity/mortality in diabetic patients representing a major clinical and economic issue. Pharmacological therapies, administration of growth factors, and stem cellular strategies are the most effective approaches and will be discussed in depth in this comprehensive review covering the regenerative therapies of diabetic microangiopathy.

Adverse events in clinical islet transplantation: one institutional experience

Islet transplantation is one of the most promising treatments for an unstable form of type 1 diabetes. However, islet transplantation still has some obstacles, such as low success rate of islet isolation, difficulty to obtain long-term insulin freedom, and adverse events related to transplant protocol. We describe the adverse events of current clinical islet transplantation at our institute in this report. Nine type 1 diabetic patients received 17 islet infusions from March 2005 to October 2008. The islet infusion procedure and immunosuppression regimen were based on a modified Edmonton protocol. Severe adverse events (SAEs) were defined as events that were more than grade 3 according to the Terminology Criteria for Adverse Events in Trials of Adult Pancreatic Islet Transplantation, version 4.1 (Collaborative Islet Transplant Registry, CITR). Sixteen events were reported as SAEs and among them 12 events were probably or definitely related to transplant protocols; all occurred within 1 year after infusion except for one. Five adverse events (31%) occurred within 10 days after transplantation and were related to infusion procedures. Seven events (44%) occurred after 50 days and were related to immunosuppressive therapy. SAEs related to the protocol included three events of elevated liver enzymes, two of hemorrhage into gall bladder or peritoneal cavity, two of neutropenia, two of infection, one of vomiting, one of diarrhea, and one of renal dysfunction. All events were grade 3, except for one case that was grade 4 of neutropenia. All SAEs resolved with no sequelae. Neoplasms and deaths were not observed in our study. The present study suggests need to improve both infusion procedure and immunosuppressive strategy from the view of preventing SAEs.

Current status of immunomodulatory and cellular therapies in preclinical and clinical islet transplantation

Clinical islet transplantation is a β-cell replacement strategy that represents a possible definitive intervention for patients with type 1 diabetes, offering substantial benefits in terms of lowering daily insulin requirements and reducing incidences of debilitating hypoglycemic episodes and unawareness. Despite impressive advances in this field, a limiting supply of islets, inadequate means for preventing islet rejection, and the deleterious diabetogenic and nephrotoxic side effects associated with chronic immunosuppressive therapy preclude its wide-spread applicability. Islet transplantation however allows a window of opportunity for attempting various therapeutic manipulations of islets prior to transplantation aimed at achieving superior transplant outcomes. In this paper, we will focus on the current status of various immunosuppressive and cellular therapies that promote graft function and survival in preclinical and clinical islet transplantation with special emphasis on the tolerance-inducing capacity of regulatory T cells as well as the β-cells regenerative capacity of stem cells.

Evolution of β-Cell Replacement Therapy in Diabetes Mellitus: Islet Cell Transplantation

Diabetes mellitus remains one of the leading causes of morbidity and mortality worldwide. According to the Centers for Disease Control and Prevention, approximately 23.6 million people in the United States are affected. Of these individuals, 5 to 10% have been diagnosed with Type 1 diabetes mellitus (T1DM), an autoimmune disease. Although it often appears in childhood, T1DM may manifest at any age, leading to significant morbidity and decreased quality of life. Since the 1960s, the surgical treatment for diabetes mellitus has evolved to become a viable alternative to insulin administration, beginning with pancreatic transplantation. While islet cell transplantation has emerged as another potential alternative, its role in the treatment of T1DM remains to be solidified as research continues to establish it as a truly viable alternative for achieving insulin independence. In this paper, the historical evolution, procurement, current status, benefits, risks, and ongoing research of islet cell transplantation are explored.

State of the art of clinical islet transplantation and novel protocols of immunosuppression

Clinical islet transplantation has transitioned from curiosity to realistic therapy over the past decade. An estimated 750 patients have undergone intraportal islet-alone transplantation over this period, and a smaller subset received combined islet-kidney transplants. The primary benefit of successful islet transplantation has been to eliminate severe, recurrent hypoglycemia, a problem that has been hard to eliminate by other means in 15% of those with type 1 diabetes. The secondary benefit of independence from insulin has attracted patients, but has had limited sustainability previously, especially with a single-donor graft, but recent results from four independent centers suggest marked improvement in long-term outcome, with 5-year results now approximating solitary pancreas transplantation. Emerging data confirm that islet transplantation can stabilize and reverse several secondary diabetic complications similar to whole pancreas transplantation, but larger, head-to-head trials are needed to compare islet transplantation with best medical therapies. Current goals are to extend durability, and to make islet transplantation more widely available for patients in need. Governmental and health insurance providers in several countries now reimburse islet transplantation as part of clinical care. As the safety of the procedure and of adjunctive immunosuppressive therapies improve, and benefit accrues over potential risk, islet transplantation will be offered earlier in the course of the disease, including newly diagnosed children. The role of islet transplantation in type 2 diabetes has yet to be defined. We review the current status of islet transplantation, and discuss current and future immunosuppressive protocols that will pave the way to more broad application of cellular replacement in diabetes.

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.

One hundred human pancreatic islet isolations at Baylor Research Institute

The effectiveness of pancreatic islet isolation must be maximized to make islet cell transplantation (ICT) a standard therapy. We have performed 100 human islet isolations at Baylor Research Institute including islet isolations for research, for clinical allogeneic transplantation, and for autologous islet transplantation. In this study, we analyzed the results of these isolations. First, we assessed 79 islet isolations using brain-dead donors to determine variables associated with successful islet isolation. Univariate logistic regression analysis revealed that seven variables influenced the success of islet isolation for allogeneic ICT: cause of death, mechanism of death, techniques for pancreas procurement and preservation, heavy fatty infiltration, collagenase type, dilution time, and islet purification method. Multivariate regression analysis revealed that only the current isolation protocol, the Baylor Islet Isolation Method (BIIM)-with its four required elements of pancreas procurement by the team, pancreatic ductal injection, the two-layer method with perfluorocarbon, and density-adjusted density gradient purification-had a significant positive impact on successful islet isolation (P = 0.02). Second, we compared allogeneic and autologous ICT using the BIIM. There were no significant differences in islet yields between allogeneic and autologous ICT using the BIIM; total islet yield after purification was 628 ± 84 × 10(3) IE in allogeneic ICT vs. 576 ± 49 × 10(3) IE in autologous ICT (P = 0.59). This retrospective study revealed that the BIIM provided favorable outcomes for both autologous and allogeneic ICT.

Renal and vascular benefits of C-peptide: Molecular mechanisms of C-peptide action

C-peptide has long been thought to be an inert byproduct of insulin production, but it has become apparent, and accepted, that C-peptide has important biological properties. C-peptide displays beneficial effects in many tissues affected by diabetic complications, such as increased peripheral blood flow and protection from renal damage. However, the mechanisms mediating these effects remain unclear. C-peptide interacts with cellular membranes at unidentified sites distinctive of the insulin family of receptors, and signals to multiple targets known to play a role in diabetes and diabetic complications, such as Na⁺/K⁺-ATPase and NOS. In general, the physiological and molecular effects of C-peptide resemble insulin, but C-peptide also possesses traits separate from those of insulin. These basic studies have been confirmed in human studies, suggesting that C-peptide may lend itself to clinical applications. However, the molecular and physiological properties of C-peptide are not completely elucidated, and large clinical studies have not begun. In order to further these goals, we critically summarize the current state of knowledge regarding C-peptide’s renal and vascular effects and the molecular signaling of C-peptide.

Improved function of circulating angiogenic cells is evident in type 1 diabetic islet-transplanted patients

Circulating angiogenic cells (CACs) are vascular-committed bone marrow-derived cells that are dysfunctional in type 1 diabetes (T1D). Here we studied whether restoration of normoglycemia following islet transplantation is associated with better CAC function. We carried out a cross-sectional study of 18 T1D patients, 14 insulin-independent islet-transplanted patients (ITA) and 14 healthy controls (C) evaluating in vivo and in vitro CACs viability and function. We found that the percentage of CACs in vivo did not differ among the three groups while the number of CAC colonies obtained from T1D, but not from ITA, was reduced compared to C (C = 7.3 ± 1.9, T1D = 0.9 ± 0.4 and ITA = 4.7 ± 1.9; p < 0.05 T1D vs. all). In vitro CAC migration/differentiation were similar, while in vivo an improved angiogenic ability of ITA compared to T1D was shown (capillary density: C = 93.5 ± 22.1, T1D = 19.2 ± 2.8 and ITA = 44.0 ± 10.5, p < 0.05 T1D vs. all). Increased apoptosis and lesser IL-8 secretion were evident in CACs obtained from T1D compared to C and ITA. in vitro addition of anti-hIL-8 reduced the number of colonies obtained from C. Finally, T1D, but not ITA, had a lower endothelial-dependent dilatation (EDD) compared with C. These data suggest that CAC function is altered in T1D and may be improved after islet transplantation.

Islet versus pancreas transplantation in type 1 diabetes: competitive or complementary?

Whole organ pancreas and pancreatic islet transplantation are currently the only forms of clinically available β-cell replacement. Both therapeutic options can provide good glycemic control and prevention or stabilization of diabetic complications, but at the price of permanent immunosuppression. Therefore, the indication for transplantation of type 1 diabetes patients must be balanced carefully and should be restricted to a subgroup of patients with extreme lability of metabolic control and frequent hypoglycemia despite optimal medical therapy.

Bone marrow-derived stem cell transplantation for the treatment of insulin-dependent diabetes

The bone marrow is an invaluable source of adult pluripotent stem cells, as it gives rise to hematopoietic stem cells, endothelial progenitor cells, and mesenchymal cells, amongst others. The use of bone marrow-derived stem cell (BMC) transplantation (BMT) may be of assistance in achieving tissue repair and regeneration, as well as in modulating immune responses in the context of autoimmunity and transplantation. Ongoing clinical trials are evaluating the effects of BMC to preserve functional beta-cell mass in subjects with type 1 and type 2 diabetes, and to favor engraftment and survival of transplanted islets. Additional trials are evaluating the impact of BMT (i.e., mesenchymal stem cells) on the progression of diabetes complications. This article reviews the progress in the field of BMC for the treatment of subjects with insulin-dependent diabetes, and summarizes clinical data of pilot studies performed over the last two decades at our research center by combining allogeneic islet transplantation with donor-specific BMC. Clinical data is summarized from pilot studies performed at our research center over the last two decades.

Pancreas vs. islet transplantation: a call on the future

PURPOSE OF REVIEW

The aim of this article is to review recent reports on whole pancreas and islet cell transplantation. It focuses on 'what the call to the future looks like' for both therapies as treatment options for those type 1 diabetes patients who do not respond well to conventional therapy.

RECENT FINDINGS

The major benefit of pancreas transplantation is the reversal of diabetes improvement of diabetes complications. Although the procedure requires major surgery and life-long immunosuppression, it remains the gold standard for a specific population of patients who suffer from type 1 diabetes and who do not respond to conventional therapy. Allogeneic islet transplantation is a promising alternative to pancreas transplantation, but patient outcomes remain less than optimal and significant progress is required in order for this procedure to be considered a reliable therapy.

CONCLUSION

Several factors have to be taken into consideration before making the decision of which of these procedures would better suit a patient with type 1 diabetes.

Successes and disappointments with clinical islet transplantation

Transplantation of pancreatic islets is considered a therapeutic option for patients with type 1 diabetes mellitus who have life-threatening hypoglycaemic episodes. After the procedure, a decrease in the frequency and severity of hypoglycaemic episodes and sustained graft function as indicated by detectable levels of C-peptide can be seen in the majority of patients. However, true insulin independence, if achieved, usually lasts for at most a few years. Apart from the low insulin independence rates, reasons for concern regarding this procedure are the side effects of the immunosuppressive therapy, allo-immunization, and the high costs. Moreover, whether islet transplantation prevents the progression of diabetic micro- and macrovascular complications is largely unknown. Areas of current research include the development of less toxic immunosuppressive regimens, the control of the inflammatory reaction immediately after transplantation, the identification of the optimal anatomical site for islet infusion, and the possibility to encapsulate transplanted islets to protect them from the allo-immune response. At present, pancreatic islet transplantation is still an experimental procedure, which is only indicated for a highly selected group of type 1 diabetic patients with life-threatening hypoglycaemic episodes.

[Pancreas and islet transplantation]

Pancreas transplantation is a successful and effective procedure resulting in tight glucose control. Due to the postoperative morbidity and the need for immunosuppression pancreas transplantation should be considered in patients with type I diabetes at the time of kidney transplantation. Besides this pancreas transplantation alone can be taken into consideration for patients with very poor metabolic control and quality of life despite optimal medical treatment. Recently, islet transplantation became a less invasive alternative to pancreas transplantation. Due to the lack of long-term follow-up and due to the need of multiple donor grafts for one recipient, islet transplantation should be performed under experimental settings in experienced centers. New developments in protecting transplanted islets and in the induction of donor-specific tolerance could increase the indication to perform the procedure. Therefore alternative sources of beta-cells have to be identified.

Protection of human pancreatic islets using a lentiviral vector expressing two genes: cFLIP and GFP

Pancreatic islet transplantation can provide insulin independence to diabetic patients. However, apoptosis of islets often leads to early graft failure. Genetic engineering with protective gene(s) can improve the viability of these cells. Here we show successful transduction of human islets with a feline immunodeficiency virus (FIV) vector expressing both a cytoprotective (cFLIP) gene and the green fluorescent protein (GFP). Despite using low virus titers to maximize safety, transduced islets expressed both genes, resulting in improved beta-cell metabolic activity and viability. Although only approximately 10% of total islet cells were transduced, the significant viability advantages suggest a "barrier" effect in which protecting the periphery of the islet shields the core. These results provide the first demonstration that a lentiviral vector can express two genes in islets. Furthermore, the engineered islets are resistant to a variety of apoptotic stimuli, suggesting the potential of this approach in enhancing the viability of transplanted cells.

The clinical impact of islet transplantation

Islet cell transplantation has recently emerged as one of the most promising therapeutic approaches to improving glycometabolic control in diabetic patients and, in many cases, achieving insulin independence. Unfortunately, many persistent flaws still prevent islet transplantation from becoming the gold standard treatment for type 1 diabetic patients. We review the state of the art of islet transplantation, outcomes, immunosuppression and--most important--the impact on patients' survival and long-term diabetic complications and eventual alternative options. Finally, we review the many problems in the field and the challenges to islet survival after transplantation. The rate of insulin independence 1 year after islet cell transplantation has significantly improved in recent years (60% at 1 year posttransplantation compared with 15% previously). Recent data indicate that restoration of insulin secretion after islet cell transplantation is associated with an improvement in quality of life, with a reduction in hypoglycemic episodes and potentially with a reduction in long-term diabetic complications. Once clinical islet transplantation has been successfully established, this treatment could even be offered to diabetic patients long before the onset of diabetic complications.

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.

Metabolic and immunological features of the failing islet-transplanted patient

OBJECTIVE

This retrospective study was designed to identify metabolic and immune predictors of early islet allograft failure.

RESEARCH DESIGN AND METHODS

We measured several metabolic and immunological markers at the time of pretransplant and several time points posttransplantation in 17 patients with long-term functioning graft (long fx) and 20 patients with short-term functioning graft (short fx).

RESULTS

The short fx group showed higher insulin resistance, altered proinsulin processing, lower soluble interleukin-2 receptor (sIL-2r) (marker of T-cell activation), and higher soluble FasL (marker of apoptosis) during the entire follow-up, particularly at time of failure.

CONCLUSIONS

Patients who experienced an early failure of islet allograft showed specific metabolic and immunological signs long before islet failure.