Total pancreatectomy with islet autotransplantation reduces resource utilization in pediatric patients.

BACKGROUND: Chronic pancreatitis (CP) is associated with poor quality of life. Total pancreatectomy with islet autotransplantation (TPIAT) has traditionally been reserved for patients with refractory disease. We hypothesized TPIAT would lead to decreased costs and resource utilization after operation in children. METHODS: Retrospective review of 39 patients who underwent TPIAT at a single children's hospital was performed. All inpatient admissions, imaging, endoscopic procedures, and operations were recorded for the year prior to and following operation. Costs were determined from Centers for Medicare and Medicaid Services. RESULTS: Median hospital admissions before operation was 5 (IQR:2-7) and decreased to 2 (IQR:1-3) after (p < 0.01). Median total cost for the year before operation was $36,006 (IQR:$19,914-$47,680), decreasing to $24,900 postoperatively (IQR:$17,432-$44,005, p = 0.03). Removing cost of TPIAT itself, total cost was further reduced to $10,564 (IQR:$3096-$29,669, p < 0.01). CONCLUSION: In children with debilitating CP, TPIAT has favorable impact on cost reduction, hospitalizations, and invasive procedures. Early intervention at a specialized pancreas center of excellence should be considered to decrease future resource utilization and costs among children.

Economics of Beta-Cell Replacement Therapy.

PURPOSE OF REVIEW: Type 1 diabetes impacts 1.3 million people in the USA with a total direct lifetime medical cost of $133.7 billion. Management requires a mix of daily exogenous insulin administration and frequent glucose monitoring. Decision-making by the individual can be burdensome. RECENT FINDINGS: Beta-cell replacement, which involves devices protecting cells from autoimmunity and allo-rejection, aims at restoring physiological glucose regulation and improving clinical outcomes in patients. Given the significant burden of T1D in the healthcare systems, cost-effectiveness analyses can drive innovation and policymaking in the area. This review presents the health economics analyses performed for donor-derived islet transplantation and the possible outcomes of stem cell-derived beta cells. Long-term cost-effectiveness of islet transplantation depends on the engraftment of these transplants, and the expenses and thresholds assumed by healthcare systems in different countries. Early health technology assessment analyses for stem cell-derived beta-cell replacement suggest manufacturing optimization is necessary to reduce upfront costs.

Cost and Scalability Analysis of Porcine Islet Isolation for Islet Transplantation: Comparison of Juvenile, Neonatal and Adult Pigs.

The limited availability of human islets has led to the examination of porcine islets as a source of clinically suitable tissue for transplantation in patients with diabetes mellitus. Islets from porcine donors are commonly used in both in vitro and in vivo experiments studying diabetes mellitus. However, there are significant differences in quality and quantity of islet yield depending on donor pig age, as well as substantial differences in the costs of pancreas procurement in adult versus neonatal and juvenile pigs. In this study, we compared the total cost per islet of juvenile pig pancreata with that of neonatal and adult pigs. Although adult porcine pancreata yield, on average, more than five times the amount of islets than do juvenile and neonatal pancreata, we found that the high price of adult pigs led to the cost per islet being more than twice that of juvenile and neonatal islets (US $0.09 vs $0.04 and $0.02, respectively). In addition, neonatal and juvenile islets are advantageous in their scalability and retention of viability after culture. Our findings indicate that isolating neonatal and juvenile porcine islets is more cost-effective and scalable than isolating adult porcine islets.

Stem cells and beta cell replacement therapy: a prospective health technology assessment study.

BACKGROUND: Although current beta cell replacement therapy is effective in stabilizing glycemic control in highly selected patients with refractory type 1 diabetes, many hurdles are inherent to this and other donor-based transplantation methods. One solution could be moving to stem cell-derived transplant tissue. This study investigates a novel stem cell-derived graft and implant technology and explores the circumstances of its cost-effectiveness compared to intensive insulin therapy. METHODS: We used a manufacturing optimization model based on work by Simaria et al. to model cost of the stem cell-based transplant doses and integrated its results into a cost-effectiveness model of diabetes treatments. The disease model simulated marginal differences in clinical effects and costs between the new technology and our comparator intensive insulin therapy. The form of beta cell replacement therapy was as a series of retrievable subcutaneous implant devices which protect the enclosed pancreatic progenitors cells from the immune system. This approach was presumed to be as effective as state of the art islet transplantation, aside from immunosuppression drawbacks. We investigated two different cell culture methods and several production and delivery scenarios. RESULTS: We found the likely range of treatment costs for this form of graft tissue for beta cell replacement therapy. Additionally our results show this technology could be cost-effective compared to intensive insulin therapy, at a willingness-to-pay threshold of $100,000 per quality-adjusted life year. However, results also indicate that mass production has by far the best chance of providing affordable graft tissue, while overall there seems to be considerable room for cost reductions. CONCLUSIONS: Such a technology can improve treatment access and quality of life for patients through increased graft supply and protection. Stem cell-based implants can be a feasible way of treating a wide range of patients with type 1 diabetes.

A multicenter study of total pancreatectomy with islet autotransplantation (TPIAT): POST (Prospective Observational Study of TPIAT).

BACKGROUND/OBJECTIVES: Total pancreatectomy with islet autotransplantation (TPIAT) is considered for managing chronic pancreatitis in selected patients when medical and endoscopic interventions have not provided adequate relief from debilitating pain. Although more centers are performing TPIAT, we lack large, multi-center studies to guide decisions about selecting candidates for and timing of TPIAT. METHODS: Multiple centers across the United States (9 to date) performing TPIAT are prospectively enrolling patients undergoing TPIAT for chronic pancreatitis into the Prospective Observational Study of TPIAT (POST), a NIDDK funded study with a goal of accruing 450 TPIAT recipients. Baseline data include participant phenotype, pancreatitis history, and medical/psychological comorbidities from medical records, participant interview, and participant self-report (Medical Outcomes Survey Short Form-12, EQ-5D, andPROMIS inventories for pain interference, depression, and anxiety). Outcome measures are collected to at least 1 year after TPIAT, including the same participant questionnaires, visual analog pain scale, pain interference scores, opioid requirements, insulin requirements, islet graft function, and hemoglobin A1c. Health resource utilization data are collected for a cost-effectiveness analysis. Biorepository specimens including urine, serum/plasma, genetic material (saliva and blood), and pancreas tissue are collected for future study. CONCLUSIONS: This ongoing multicenter research study will enroll and follow TPIAT recipients, aiming to evaluate patient selection and timing for TPIAT to optimize pain relief, quality of life, and diabetes outcomes, and to measure the procedure's cost-effectiveness. A biorepository is also established for future ancillary studies.

Randomised, prospective, medico-economic nationwide French study of islet transplantation in patients with severely unstable type 1 diabetes: the STABILOT study protocol.

INTRODUCTION: Islet transplantation may be an appropriate treatment option for patients with severely unstable type 1 diabetes experiencing major glucose variability with severe hypoglycaemia despite intensive insulin therapy. Few data are available on the costs associated with islet transplantation in relation to its benefits. The STABILOT study proposes to assess the economic impact of islet transplantation in comparison with the current best medical treatment defined as sensor-augmented pump (SAP) therapy. METHODS: The trial will adopt an open-label, randomised, multicentred design. The study will include 30 patients with severely unstable type 1 diabetes. Eligible participants will be 18-65 years old, with type 1 diabetes duration >5 years, a negative basal or stimulated C-peptide, and severe instability defined by persistent, recurrent and disabling severe hypoglycaemia, despite optimised medical treatment. Participants will be randomised into two groups: one group with immediate registration for islet transplantation, and one group with delayed registration for 1 year while patients receive SAP therapy. The primary endpoint will be the incremental cost-utility ratio at 1 year between islet transplantation and SAP therapy. Perspectives of both the French Health Insurance System and the hospitals will be retained. ETHICS AND DISSEMINATION: Ethical approval has been obtained at all sites. The trial has been approved by ClinicalTrials.gov (Trial registration ID NCT02854696). All participants will sign a free and informed consent form before randomisation. Results of the study will be communicated during national and international meetings in the field of diabetes and transplantation. A publication will be sought in journals usually read by physicians involved in diabetes care, transplantation and internal medicine. TRIAL REGISTRATION NUMBER: NCT02854696; Pre-results.

Cost and clinical outcome of islet transplantation in Norway 2010-2015.

Islet transplantation is a minimally invasive ß-cell replacement strategy. Islet transplantation is a reimbursed treatment in Norway. Here, we summarize the cost and clinical outcome of 31 islet transplantations performed at Oslo University Hospital (OUS) from January 2010 to June 2015. Patients were retrospectively divided into three groups. Thirteen patients received either one or two islet transplantation alone (ITA), while five patients received islet transplantation after previous solid organ transplantation. For the group receiving 2 ITA, Kaplan-Meier estimates show an insulin independence of 20% more than 4 years after their last transplantation. An estimated 70% maintain at least partial graft function, defined as fasting C-peptide >0.1 nmol L-1 , and 47% maintain a HbA1c below 6.5% or 2 percent points lower than before ITA. For all groups combined, we estimate that 44% of the patients have a 50% reduction in insulin requirement 4 years after the initial islet transplantation. The average cost for an islet transplantation procedure was 347 297±60 588 NOK, or 35 424±6182 EUR, of which isolation expenses represent 34%. We hereby add to the common pool of growing experience with islet transplantation and also describe the cost of the treatment at our center.

National Institutes of Health-Sponsored Clinical Islet Transplantation Consortium Phase 3 Trial: Manufacture of a Complex Cellular Product at Eight Processing Facilities.

Eight manufacturing facilities participating in the National Institutes of Health-sponsored Clinical Islet Transplantation (CIT) Consortium jointly developed and implemented a harmonized process for the manufacture of allogeneic purified human pancreatic islet (PHPI) product evaluated in a phase 3 trial in subjects with type 1 diabetes. Manufacturing was controlled by a common master production batch record, standard operating procedures that included acceptance criteria for deceased donor organ pancreata and critical raw materials, PHPI product specifications, certificate of analysis, and test methods. The process was compliant with Current Good Manufacturing Practices and Current Good Tissue Practices. This report describes the manufacturing process for 75 PHPI clinical lots and summarizes the results, including lot release. The results demonstrate the feasibility of implementing a harmonized process at multiple facilities for the manufacture of a complex cellular product. The quality systems and regulatory and operational strategies developed by the CIT Consortium yielded product lots that met the prespecified characteristics of safety, purity, potency, and identity and were successfully transplanted into 48 subjects. No adverse events attributable to the product and no cases of primary nonfunction were observed.

Cost effectiveness and value of information analyses of islet cell transplantation in the management of 'unstable' type 1 diabetes mellitus.

BACKGROUND: Islet cell transplantation is a method to stabilize type 1 diabetes patients with hypoglycemia unawareness and unstable blood glucose levels by reducing insulin dependency and protecting against severe hypoglycemia through restoring endogenous insulin secretion. This study analyses the current cost-effectiveness of this technology and estimates the value of further research to reduce uncertainty around cost-effectiveness. METHODS: We performed a cost-utility analysis using a Markov cohort model with a mean patient age of 49 to simulate costs and health outcomes over a life-time horizon. Our analysis used intensive insulin therapy (IIT) as comparator and took the provincial healthcare provider perspective. Cost and effectiveness data for up to four transplantations per patient came from the University of Alberta hospital. Costs are expressed in 2012 Canadian dollars and effectiveness in quality-adjusted life-years (QALYs) and life years. To characterize the uncertainty around expected outcomes, we carried out a probabilistic sensitivity analysis within the Bayesian decision-analytic framework. We performed a value-of-information analysis to identify priority areas for future research under various scenarios. We applied a structural sensitivity analysis to assess the dependence of outcomes on model characteristics. RESULTS: Compared to IIT, islet cell transplantation using non-generic (generic) immunosuppression had additional costs of $150,006 ($112,023) per additional QALY, an average gain of 3.3 life years, and a probability of being cost-effective of 0.5 % (28.3 %) at a willingness-to-pay threshold of $100,000 per QALY. At this threshold the non-generic technology has an expected value of perfect information (EVPI) of $260,744 for Alberta. This increases substantially in cost-reduction scenarios. The research areas with the highest partial EVPI are costs, followed by natural history, and effectiveness and safety. CONCLUSIONS: Current transplantation technology provides substantial improvements in health outcomes over conventional therapy for highly selected patients with 'unstable' type 1 diabetes. However, it is much more costly and so is not cost-effective. The value of further research into the cost-effectiveness is dependent upon treatment costs. Further, we suggest the value of information should not only be derived from current data alone when knowing that this data will most likely change in the future.

A Comparative Analysis of the Safety, Efficacy, and Cost of Islet Versus Pancreas Transplantation in Nonuremic Patients With Type 1 Diabetes.

Few current studies compare the outcomes of islet transplantation alone (ITA) and pancreas transplantation alone (PTA) for type 1 diabetes (T1D). We examined these two beta cell replacement therapies in nonuremic patients with T1D with respect to safety, graft function and cost. Sequential patients received PTA (n = 15) or ITA (n = 10) at our institution. Assessments of graft function included duration of insulin independence; glycemic control, as measured by hemoglobin A1c; and elimination of severe hypoglycemia. Cost analysis included all normalized costs associated with transplantation and inpatient management. ITA patients received one (n = 6) or two (n = 4) islet transplants. Mean duration of insulin independence in this group was 35 mo; 90% were independent at 1 year, and 70% were independent at 3 years. Mean duration of insulin independence in PTA was 55 mo; 93% were insulin independent at 1 year, and 64% were independent at 3 years. Glycemic control was comparable in all patients with functioning grafts, as were overall costs ($138 872 for ITA, $134 748 for PTA). We conclude that with advances in islet isolation and posttransplant management, ITA can produce outcomes similar to PTA and represents a clinically viable option to achieve long-term insulin independence in selected patients with T1D.

Using the cost-effectiveness of allogeneic islet transplantation to inform induced pluripotent stem cell-derived ß-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 ß-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 ß-cell therapy would dominate the comparator over an 8-year time horizon.

Clinical implementation of islet transplantation: A current assessment.

Beta-cell replacement is the only physiologically relevant alternative to insulin injections in patients with type 1 diabetes (T1D). Pancreas and islet transplantation from deceased organ donors can provide a new beta-cell pool to produce insulin, help blood glucose management, and delay secondary diabetes complications. For children and adolescents with T1D, whole pancreas transplantation is not a viable option because of surgical complications, whereas islet transplantation, even if it is procedurally simpler, must still overcome the burden of immunosuppression to become a routine therapy for children in the future.

Human pancreatic islet transplantation: an update and description of the establishment of a pancreatic islet isolation laboratory.

Type 1 diabetes mellitus (T1DM) is associated with chronic complications that lead to high morbidity and mortality rates in young adults of productive age. Intensive insulin therapy has been able to reduce the likelihood of the development of chronic diabetes complications. However, this treatment is still associated with an increased incidence of hypoglycemia. In patients with "brittle T1DM", who have severe hypoglycemia without adrenergic symptoms (hypoglycemia unawareness), islet transplantation may be a therapeutic option to restore both insulin secretion and hypoglycemic perception. The Edmonton group demonstrated that most patients who received islet infusions from more than one donor and were treated with steroid-free immunosuppressive drugs displayed a considerable decline in the initial insulin independence rates at eight years following the transplantation, but showed permanent C-peptide secretion, which facilitated glycemic control and protected patients against hypoglycemic episodes. Recently, data published by the Collaborative Islet Transplant Registry (CITR) has revealed that approximately 50% of the patients who undergo islet transplantation are insulin independent after a 3-year follow-up. Therefore, islet transplantation is able to successfully decrease plasma glucose and HbA1c levels, the occurrence of severe hypoglycemia, and improve patient quality of life. The goal of this paper was to review the human islet isolation and transplantation processes, and to describe the establishment of a human islet isolation laboratory at the Endocrine Division of the Hospital de Clínicas de Porto Alegre - Rio Grande do Sul, Brazil.

Human pancreatic islet transplantation: an update and description of the establishment of a pancreatic islet isolation laboratory

Type 1 diabetes mellitus (T1DM) is associated with chronic complications that lead to high morbidity and mortality rates in young adults of productive age. Intensive insulin therapy has been able to reduce the likelihood of the development of chronic diabetes complications. However, this treatment is still associated with an increased incidence of hypoglycemia. In patients with “brittle T1DM”, who have severe hypoglycemia without adrenergic symptoms (hypoglycemia unawareness), islet transplantation may be a therapeutic option to restore both insulin secretion and hypoglycemic perception. The Edmonton group demonstrated that most patients who received islet infusions from more than one donor and were treated with steroid-free immunosuppressive drugs displayed a considerable decline in the initial insulin independence rates at eight years following the transplantation, but showed permanent C-peptide secretion, which facilitated glycemic control and protected patients against hypoglycemic episodes. Recently, data published by the Collaborative Islet Transplant Registry (CITR) has revealed that approximately 50% of the patients who undergo islet transplantation are insulin independent after a 3-year follow-up. Therefore, islet transplantation is able to successfully decrease plasma glucose and HbA1c levels, the occurrence of severe hypoglycemia, and improve patient quality of life. The goal of this paper was to review the human islet isolation and transplantation processes, and to describe the establishment of a human islet isolation laboratory at the Endocrine Division of the Hospital de Clínicas de Porto Alegre – Rio Grande do Sul, Brazil.

Islet transplantation from a nationally funded UK centre reaches socially deprived groups and improves metabolic outcomes.

AIMS/HYPOTHESIS: Type 1 diabetes complicated by hypoglycaemia is prevalent in socioeconomically deprived populations. Islet transplantation is of proven efficacy in type 1 diabetes complicated by hypoglycaemia, but it is not known if nationally funded programmes reach the socioeconomically deprived. Our aim was to determine: (1) socioeconomic indices in participants referred to our nationally funded programme; and (2) if metabolic outcomes in our transplant recipients were improved. METHODS: Participants referred (n = 106) and receiving transplants (n = 18; 32 infusions) were examined with respect to socioeconomic status (deprivation category score) and their ability to work and drive. In participants followed for ≥12 months after transplantation, metabolic and anthropometric measurements (n = 14) were recorded pre- and post-transplant (assessed ~1, ~3, ~6 and ~12 months with mixed-meal tolerance tests and 6 day continuous glucose monitoring assessments). Donor data was also examined. RESULTS: There was a greater prevalence of socioeconomic deprivation in referred and transplant recipients than the general population (p < 0.05). Of the transplant recipients, 73% were socioeconomically deprived, 88% did not hold a driver's license and 94% had reduced ability to work (all p < 0.01 vs referred participants). Donors were predominantly obese and included circulatory death donors. At 12 months, 93% of participants who had received transplants had graft function, diminished frequency of hypoglycaemia (10 [4-11] vs 0 [0-2] hypoglycaemic episodes/week), improved awareness of hypoglycaemia (Gold score 7 [5-7] vs 1 [1-2]) and glycaemic control (HbA1c: 7.9% [7.2-8.5%]; 63 [55-69] mmol/mol vs 7.2% [6.8-7.5%]; 55 [51-58] mmol/mol), diminished glycaemic lability and decreased central adiposity (all p < 0.05). CONCLUSIONS/INTERPRETATION: A nationally funded islet transplant programme reaches the socioeconomically deprived and outcomes are significantly improved in this group.

Cost-effectiveness of total pancreatectomy and islet cell autotransplantation for the treatment of minimal change chronic pancreatitis.

INTRODUCTION: The current standard of care for the management of minimal change chronic pancreatitis (MCCP) is medical management. Controversy exists, however, regarding the use of surgical intervention for MCCP. We hypothesized that total pancreatectomy and islet cell autotransplantation (TPIAT) decreases long-term resource utilization and improves quality of life, justifying initial costs and risks. METHODS: Detailed perioperative outcomes from 46 patients with MCCP populated a Markov model comparing medical management to TPIAT. Mortality, complications, readmission rates, insulin and narcotic use, imaging, and endoscopy were included in the model. Outcomes reported were survival, measured in quality-adjusted life years (QALYs), and costs, in 2013 US dollars. RESULTS: In medical patients, annual mean hospital admissions were 1.6 (range = 0-11), endoscopy 1.4 (0-6), and imaging (CT/MRI) 1.5 (0-4). In surgical patients, there were no perioperative deaths, with complication and 30-day readmission rates of 47 and 37%. One year after TPIAT, annual mean admissions, endoscopy, and imaging had decreased to 0.9 (0-4), 0.4 (0-2), and 0.9 (0-5); monthly narcotic use decreased from 138 to 37 morphine equivalents (p = 0.012). Cost and survival for TPIAT versus medical management were $153,575/14.9 QALYs and $196,042/11.5 QALYs, respectively. CONCLUSIONS: In patients with MCCP, TPIAT is associated with decreased cost and increased quality-adjusted survival. Providers and insurers should more enthusiastically embrace TPIAT use as a more effective cost-saving strategy.

Total pancreatectomy with islet autotransplantation: summary of a National Institute of Diabetes and Digestive and Kidney diseases workshop.

A workshop sponsored by the National Institute of Diabetes and Digestive and Kidney Diseases focused on research gaps and opportunities in total pancreatectomy with islet autotransplantation (TPIAT) for the management of chronic pancreatitis (CP). The session was held on July 23, 2014, and structured into 5 sessions: (1) patient selection, indications, and timing; (2) technical aspects of TPIAT; (3) improving success of islet autotransplantation; (4) improving outcomes after total pancreatectomy; and (5) registry considerations for TPIAT. The current state of knowledge was reviewed; knowledge gaps and research needs were specifically highlighted. Common themes included the need to identify which patients best benefit from and when to intervene with TPIAT, current limitations of the surgical procedure, diabetes remission and the potential for improvement, opportunities to better address pain remission, gastrointestinal complications in this population, and unique features of children with CP considered for TPIAT. The need for a multicenter patient registry that specifically addresses the complexities of CP and total pancreatectomy outcomes as well as postsurgical diabetes outcomes was repeatedly emphasized.

Expanding the indications of pancreas transplantation alone.

OBJECTIVES: Total pancreatectomy (TP) is associated with postoperative endocrine and exocrine insufficiency. Especially, insulin therapy reduces quality of life and may lead to long-term complications. We review the literature with regard to the potential option of pancreas transplantation alone (PTA) after TP in patients with chronic pancreatitis or benign tumors. METHODS: A MEDLINE search (1958-2013) using the terminologies pancreas transplantation, pancreas transplantation alone, total pancreatectomy, morbidity, mortality, insulin therapy, and quality of life was performed. In addition, the current book and congress publications were reviewed. RESULTS: Total pancreatectomy after benign and borderline tumors as well as chronic pancreatitis is continuously increasing. Despite improvement of exogenous insulin therapy, more than 50% of these patients experience severe glucose control problems, which cause up to 50% long-term mortality. Pancreas transplantation alone can cure both endocrine and exocrine insufficiency and reduce the associated risks. The 3-year graft and patient survival rates after PTA are up to 73% and 100%, respectively. CONCLUSIONS: Pancreas transplantation alone after TP in patients with pancreatitis or benign tumors improves the recipient's quality of life and reduces long-term mortality. Considering the amount of available organs and potential candidates, PTA can be a treatment option for patients after TP with chronic pancreatitis or benign tumors.

Has the gap between pancreas and islet transplantation closed?

Both pancreas and islet transplantations are therapeutic options for complicated type 1 diabetes. Until recent years, outcomes of islet transplantation have been significantly inferior to those of whole pancreas. Islet transplantation is primarily performed alone in patients with severe hypoglycemia, and recent registry reports have suggested that results of islet transplantation alone in this indication may be about to match those of pancreas transplant alone in insulin independence. Figures of 50% insulin independence at 5 years for either procedure have been cited. In this article, we address the question whether islet transplantation has indeed bridged the gap with whole pancreas. Looking at the evidence to answer this question, we propose that although pancreas may still be more efficient in taking recipients off insulin than islets, there are in fact numerous "gaps" separating both procedures that must be taken into the equation. These "gaps" relate to organ utilization, organ allocation, indication for transplantation, and morbidity. In-depth analysis reveals that islet transplantation, in fact, has an edge on whole pancreas in some of these aspects. Accordingly, attempts should be made to bridge these gaps from both sides to achieve the same level of success with either procedure. More realistically, it is likely that some of these gaps will remain and that both procedures will coexist and complement each other, to ensure that ß cell replacement can be successfully implemented in the greatest possible number of patients with type 1 diabetes.

Engraftment versus immunosuppression: cost-benefit analysis of immunosuppression after intrahepatic murine islet transplantation.

OBJECTIVE: Immunosuppression (IS) in islet transplantation (Tx) is a double-edged sword: it prevents immunoreaction but has the potential to impair islet engraftment. The aim of this study was to identify in murine animal models the IS platform with the best balance between these two opposite effects. METHODS: To study the impact of IS on islet engraftment diabetic C57BL/6 mice were transplanted with 350 syngeneic islets through the portal vein and treated once-daily with either rapamycin (RAPA; 0.1-0.5-1 mg/kg ip), tacrolimus (FK506; 0.1-0.5-1 mg/kg ip), mycophenolate mofetil (MMF; 60-120-300 mg/kg oral) or vehicle for 14 days. Islet function was evaluated by measuring not-fasting glycemia and by performing an IVGTT on days 15 and 30 post-Tx. RESULTS: RAPA ≥0.5 mg/Kg, FK506 ≥0.5 mg/Kg, and MMF ≥120 mg/kg had detrimental effects on islet engraftment but not on the function of islets already engrafted in the liver. The effect on engraftment was irreversible and persisted even after IS withdrawal. The lower dose of IS that did not affect engraftment was tested for preventing rejection in the full mismatch allogeneic Tx BALB/c to C57BL/6 model. RAPA and/or FK506 were inefficient in preventing rejection, even when anti-IL2R mAb was added to the IS regimen. On the other hand, MMF alone or in association with FK506 significantly prolonged the time to islet rejection. CONCLUSION: IS showed profound dose-dependent deleterious effects on islet cell engraftment. The MMF/FK506 combination proved the best balance with less toxicity at the time of engraftment and more efficacy in controlling graft rejection.