Human Pancreatic Islet Transplantation Research Articles

Innovations in bio-engineering and cell-based approaches to address immunological challenges in islet transplantation.

Human allogeneic pancreatic islet transplantation is a life-changing treatment for patients with severe Type 1 Diabetes (T1D) who suffer from hypoglycemia unawareness and high risk of severe hypoglycemia. However, intensive immunosuppression is required to prevent immune rejection of the graft, that may in turn lead to undesirable side effects such as toxicity to the islet cells, kidney toxicity, occurrence of opportunistic infections, and malignancies. The shortage of cadaveric human islet donors further limits islet transplantation as a treatment option for widespread adoption. Alternatively, porcine islets have been considered as another source of insulin-secreting cells for transplantation in T1D patients, though xeno-transplants raise concerns over the risk of endogenous retrovirus transmission and immunological incompatibility. As a result, technological advancements have been made to protect transplanted islets from immune rejection and inflammation, ideally in the absence of chronic immunosuppression, to improve the outcomes and accessibility of allogeneic islet cell replacement therapies. These include the use of microencapsulation or macroencapsulation devices designed to provide an immunoprotective environment using a cell-impermeable layer, preventing immune cell attack of the transplanted cells. Other up and coming advancements are based on the use of stem cells as the starting source material for generating islet cells 'on-demand'. These starting stem cell sources include human induced pluripotent stem cells (hiPSCs) that have been genetically engineered to avoid the host immune response, curated HLA-selected donor hiPSCs that can be matched with recipients within a given population, and multipotent stem cells with natural immune privilege properties. These strategies are developed to provide an immune-evasive cell resource for allogeneic cell therapy. This review will summarize the immunological challenges facing islet transplantation and highlight recent bio-engineering and cell-based approaches aimed at avoiding immune rejection, to improve the accessibility of islet cell therapy and enhance treatment outcomes. Better understanding of the different approaches and their limitations can guide future research endeavors towards developing more comprehensive and targeted strategies for creating a more tolerogenic microenvironment, and improve the effectiveness and sustainability of islet transplantation to benefit more patients.

The establishment of pancreatic islet isolation in India – an update on human pancreatic islet transplantation

The establishment of pancreatic islet isolation in India – an update on human pancreatic islet transplantation

Immune Protection of Stem Cell-Derived Islet Cell Therapy for Treating Diabetes.

Insulin injection is currently the main therapy for type 1 diabetes (T1D) or late stage of severe type 2 diabetes (T2D). Human pancreatic islet transplantation confers a significant improvement in glycemic control and prevents life-threatening severe hypoglycemia in T1D patients. However, the shortage of cadaveric human islets limits their therapeutic potential. In addition, chronic immunosuppression, which is required to avoid rejection of transplanted islets, is associated with severe complications, such as an increased risk of malignancies and infections. Thus, there is a significant need for novel approaches to the large-scale generation of functional human islets protected from autoimmune rejection in order to ensure durable graft acceptance without immunosuppression. An important step in addressing this need is to strengthen our understanding of transplant immune tolerance mechanisms for both graft rejection and autoimmune rejection. Engineering of functional human pancreatic islets that can avoid attacks from host immune cells would provide an alternative safe resource for transplantation therapy. Human pluripotent stem cells (hPSCs) offer a potentially limitless supply of cells because of their self-renewal ability and pluripotency. Therefore, studying immune tolerance induction in hPSC-derived human pancreatic islets will directly contribute toward the goal of generating a functional cure for insulin-dependent diabetes. In this review, we will discuss the current progress in the immune protection of stem cell-derived islet cell therapy for treating diabetes.

Differential sensitivity of human islets from obese versus lean donors to chronic high glucose or palmitate.

Due to the shortage of multi-organ donors, human pancreatic islet transplantation has now been extended to islets originating from obese subjects. In this study, our aim is to compare the respective sensitivity of human islets from lean vs obese donors to chronic high glucose or high palmitate. Human islets were isolated from pancreases harvested from brain-dead multi-organ donors. Islets were cultured during 72 hours in the presence of moderate (16.7 mmol/L) or high (28 mmoL/L) glucose concentrations, or glucose (5.6 mmoL/L) and palmitate (0.4 mmoL/L), before measurement of their response to glucose. We first observed a greater insulin response in islets from obese donors under both basal and high-glucose conditions, confirming their hyperresponsiveness to glucose. When islets from obese donors were cultured in the presence of moderate or high glucose concentrations, insulin response to glucose remained unchanged or was slightly reduced, as opposed to that observed in lean subjects. Moreover, culturing islets from obese donors with high palmitate also induced less reduction in insulin response to glucose than in lean subjects. This partial protection of obese islets is associated with less induction of inducible nitric oxide synthase in islets, together with a greater expression of the transcription factor forkhead box O1 (FOXO1). Our data suggest that in addition to an increased sensitivity to glucose, islets from obese subjects can be considered as more resistant to glucose and fatty acid excursions and are thus valuable candidates for transplantation.

Role of Automated Insulin Delivery (Artificial Pancreas) in Islet Transplantation: An In Silico Assessment

Human pancreatic islet transplantation is a minimally-invasive procedure that is gaining recognition for the treatment of type 1 diabetes (T1D). Selected patients with unstable T1D, hypoglycemia unawareness, history of severe hypoglycemia, and glycemic lability, not successfully stabilized with intensive insulin treatment, can be offered this alternative therapy that has been shown to provide long-term glycemic control with near-normalization of hemoglobin A1c in the absence of severe hypoglycemia. Today, downsides of pancreatic islet transplantation include the need for chronic recipient immunosuppression and the limited supply of pancreatic islets. In addition, attaining long-term insulin independence remains a challenge. In this context, stabilization of a patient’s metabolic system with islet transplantation that is augmented by automated insulin delivery (AID) technology could be of significant interest. In this chapter, we want to frame and illustrate the problem of developing a combined bio-artificial system that includes an islet graft and mechanical AID. Our discussion will propose modeling approaches potentially deployable in describing glucose homeostasis after islet transplantation and will be supported by a series of in silico studies simulating post-transplant glycemic patterns and the impact of AID control strategies. To run our analyses, we used the UVA/Padova T1D Simulator – a simulation platform accepted by FDA as a substitute to animal trials in the pre-clinical evaluation of insulin treatment strategies, appropriately modified to describe the glucose-insulin regulation system in transplanted individuals. The results presented here are a very preliminary in silico assessment of the benefits of combining islet transplantation and AID. Further research, which relies on glucose and insulin data collected from transplanted patients, will be needed to optimize modeling and control strategies.

Alginate-Catechol Cross-Linking Interferes with Insulin Secretion Capacity in Isolated Murine Islet Cells.

Over the past three decades, human pancreatic islet isolation and transplantation techniques have developed as a routine clinical procedure for selected patients with type 1 diabetes mellitus. However, due to the donor shortage and required chronic systemic immunosuppression, the widespread application of islet transplantation is limited. To overcome these limitations, providing a physical barrier to transplanted islet cells with encapsulating biomaterial has emerged as a promising approach to enhance engraftment and promote islet survival post-transplantation. Alginate has been considered to be a reliable biomaterial, as it enhances islet survival and does not hamper hormone secretion. Alginate-catechol (Al-CA) hydrogel was reported to provide high mechanical strength and chemical stability without deformation over a wide range of pH values. In this study, we, demonstrated, for the first time in the literature, that encapsulation of murine pancreatic islet cells with Al-CA hydrogel does not induce cytotoxicity ex vivo for an extended period; however, it does markedly abate glucose-stimulated insulin secretion. Catechol should not be considered as a constituent for alginate gelation for encapsulating islet cells in the application of islet transplantation.

A Method of Porcine Pancreatic Islet Isolation for Microencapsulation.

Since the discovery of insulin by Banting and Best in 1921, the prognosis and treatment options for individuals with diabetes have improved. The development of various insulin types, various oral agents, and insulin pumps have improved the available medical options for individuals afflicted with diabetes. The current need for frequent blood glucose monitoring imposed by multiple daily insulin injections, result in significant life-style challenges for in individuals afflicted with Type 1 diabetes (T1D). In contrast the use of surgical interventions, such as whole organ pancreas transplantation (PT) requires less-intensive glucose monitoring while the organ is viable. Also, isolated human pancreatic islet transplantation (IT) holds similar promise as PT; however, the limited availability of human pancreata exacerbated by, the need for multiple pancreata per individual IT recipient, and issues with prolonged viability, still hamper widespread successful, and routine use of IT. The use of porcine pancreata holds promise as a viable alternative to human pancreas to significantly increase the volume of islets available to meet the needs of millions of patients afflicted with T1D. This chapter outlines our protocol utilized to reliably isolate and microencapsulate porcine islets.

Selection of polymers for application in scaffolds applicable for human pancreatic islet transplantation

The liver is currently the site for transplantation of islets in humans. This is not optimal for islets, but alternative sites in humans are not available. Polymeric scaffolds in surgically accessible areas are a solution. As human donors are rare, the polymers should not interfere with functional survival of human-islets. We applied a novel platform to test the adequacy of polymers for application in scaffolds for human-islet transplantation. Viability, functionality, and immune parameters were included to test poly(D,L-lactide-co-ε-caprolactone) (PDLLCL), poly(ethylene oxide terephthalate)/polybutylene terephthalate (PEOT/PBT) block copolymer, and polysulfone.The type of polymer influenced the functional survival of human islets. In islets cultured on PDLLCL the glucagon-producing α-cells and insulin-producing β-cells contained more hormone granules than in islets in contact with PEOT/PBT or polysulfone. This was studied with ultrastructural analysis by electron microscopy (nanotomy) during 7 d of culture. PDLLCL was also associated with statistically significant lower release of double-stranded DNA (dsDNA, a so called danger-associate molecular pattern (DAMP)) from islets on PDLLCL when compared to the other polymers. DAMPs support undesired immune responses. Hydrophilicity of the polymers did not influence dsDNA release. Islets on PDLLCL also showed less cellular outgrowth. These outgrowing cells were mainly fibroblast and some β-cells undergoing epithelial to mesenchymal cell transition. None of the polymers influenced the glucose-stimulated insulin secretion. As PDLLCL was associated with less release of DAMPs, it is a promising candidate for creating a scaffold for human islets. Our study demonstrates that for sensitive, rare cadaveric donor tissue such as pancreatic islets it might be necessary to first select materials that do not influence functionality before proposing the biomaterial for in vivo application. Our presented platform may facilitate this selection of biomaterials.

Exendin-4 protects rat islets against loss of viability and function induced by brain death

Islet quality loss after isolation from brain-dead donors still hinders the implementation of human islet transplantation for treatment of type 1 diabetes. In this scenario, systemic inflammation elicited by donor brain death (BD) is among the main factors influencing islet viability and functional impairment. Exendin-4 is largely recognized to promote anti-inflammatory and cytoprotective effects on β-cells. Therefore, we hypothesized that administration of exendin-4 to brain-dead donors might improve islet survival and insulin secretory capabilities. Here, using a rat model of BD, we demonstrate that exendin-4 administration to the brain-dead donors increases both islet viability and glucose-stimulated insulin secretion. In this model, exendin-4 treatment produced a significant decrease in interleukin-1β expression in the pancreas. Furthermore, exendin-4 treatment increased the expression of superoxide dismutase-2 and prevented BD-induced elevation in uncoupling protein-2 expression. Such observations were accompanied by a reduction in gene expression of two genes often associated with endoplasmic reticulum (ER) stress response in freshly isolated islets from treated animals, C/EBP homologous protein and immunoglobulin heavy-chain binding protein. As ER stress response has been shown to be triggered by and to participate in cytokine-induced β-cell death, we suggest that exendin-4 might exert its beneficial effects through alleviation of pancreatic inflammation and oxidative stress, which in turn could prevent islet ER stress and β-cell death. Our findings might unveil a novel strategy to preserve islet quality from brain-dead donors. After testing in the human pancreatic islet transplantation setting, this approach might sum to the ongoing effort to achieve consistent and successful single-donor islet transplantation.

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.

La thérapie cellulaire du diabète de type 1. Situation actuelle et perspective

Nowadays human pancreatic islet transplantation is a therapeutic approach in kidney transplanted patients with type 1 diabetes having severe macrovascular disease. Because of its low morbidity compared to pancreas transplantation, islet transplantation can be also proposed to patients with brittle type 1 diabetes and severe hypoglycemic events despite intensive insulin therapy. Evaluation of glucose instability is crucial for the optimal selection of candidates and to assess the benefit/risk ratio. The main objective of islet transplantation is not to reverse diabetes but to restore a satisfactory glucose control aiming to improve the clinical management and the quality of life. Further clinical trials with new immunosuppressive drugs are needed in order to improve the efficiency of islet transplantation and to apply this treatment to a large number of patients.

In vitro(re)programming of human bone marrow stromal cells toward insulin-producing phenotypes

Diabetes mellitus is a chronic disease with great social and economical impact. In all its forms, it affects nearly 200 million people worldwide (1). Type 1 diabetes (T1D) represents 10% of all cases. Because of the increase in obesity in developed countries, the prevalence of type 2 diabetes (T2D) has been rising very rapidly, affecting children and adolescents. T1D and advanced T2D are caused by a progressive loss of functional pancreatic β-cell mass within the pancreatic islets. The extraordinary results of the Edmonton protocol have shown that human pancreatic islet transplantation can normalize glycemic control of insulin-dependent diabetic patients (2). Nevertheless, this therapeutic option does not represent a significant clinical benefit for all diabetic patients; the demand of islets for transplantation is very high and human donor pancreas for isolation of islet grafts is limited. Furthermore, transplants do last no longer than 2 yr and are accompanied by significant side effects as a consequence of lifelong aggressive immunosuppression (3). Therefore, intensive search for new sources for β-cell replacement has been undertaken. Regeneration of existing mature β-cells and replacement of insulin-producing cells are current research lines that could possibly solve the problem of islet shortage. Differentiation of embryonic stem (ES) cells has been thoroughly investigated; however, results are not yet satisfactory (4–6). Adult stem/progenitor

A Meta-Analysis of the Impact of the Two-Layer Method of Preservation on Human Pancreatic Islet Transplantation

There are conflicting reports about the effectiveness of perfluorocarbons used in the two-layer method (TLM) of pancreas preservation for human islet transplantation. The mechanism of action is unclear and the optimal role of this method uncertain. The study design was a meta-analysis of the evidence that TLM improves islet isolation outcomes. Pubmed, CENTRAL, EMBASE, Science Citation Index, and BIOSIS were searched electronically in January 2008. After selecting the relevant human trials for meta-analysis data relating to donor variables, study design, primary and secondary islet isolation outcomes were extracted. Electronic searches identified eight unique citations, describing 11 human studies that were eligible for the meta-analysis. When comparing TLM with preservation in University of Wisconsin (UW) solution, there was a statistically significant higher islet yield [WMD 711.55, 95% confidence interval (CI) 140.03-1283.07] in the TLM group. The proportion of transplantable preparations obtained was not significantly different (OR 1.30, 95% CI 0.89-1.88) between the two groups. The rate of successful islet isolations for marginal organs was higher in the TLM group (OR 6.69, 95% CI 1.80-24.87). Improved oxygenation and preservation of cellular bioengertics is thought to be the main underlying mechanism, although no single mechanism has yet been confirmed. There is currently no clear evidence that the TLM is beneficial in human islet transplantation. It may improve the preservation of marginal organs.

α1-Antitrypsin monotherapy induces immune tolerance during islet allograft transplantation in mice

Human pancreatic islet transplantation offers diabetic patients tight glucose control but has low graft survival rates. The immunosuppressive drugs that are administered to graft recipients lack the antiinflammatory benefits of corticosteroids because of their diabetogenic effects. The serum protease inhibitor alpha1-antitrypsin (AAT) possesses antiinflammatory properties and reduces cytokine-mediated islet damage. In the present study, diabetic mice were grafted with allogeneic islets and treated with AAT monotherapy (n = 24). After 14 days of treatment, mice remained normoglycemic and islet allografts were functional for up to 120 treatment-free days. After graft removal and retransplantation, mice accepted same-strain islets but rejected third-strain islets, thus confirming that specific immune tolerance had been induced. Explanted grafts exhibited a population of T regulatory cells in transplant sites. According to RT-PCR, grafts contained high levels of mRNA for foxp3, cytotoxic T lymphocyte antigen-4, TGF-beta, IL-10, and IL-1 receptor antagonist; expression of proinflammatory mediators was low or absent. After implantation of skin allografts, AAT-treated mice had greater numbers of foxp3-positive cells in draining lymph nodes (DLNs) compared with control treatment mice. Moreover, dendritic cells in DLNs exhibited an immature phenotype with decreased CD86 activation marker. Although the number of CD3 transcripts decreased in the DLNs, AAT did not affect IL-2 activity in vitro. Thus, AAT monotherapy provides allografts with antiinflammatory conditions that favor development of antigen-specific T regulatory cells. Because AAT treatment in humans is safe, its use during human islet transplantation may be considered.

HUMAN REGULATORY T CELLS PREVENT ISLET ALLOGRAFT REJECTION

Background: Type 1 diabetes mellitus represents a significant burden on global healthcare. Pancreatic islet transplantation offers an effective means of controlling the disease, but shortage of donor tissue, graft thrombosis, and immunological rejection after transplantation remain obstacles that need to be overcome. Our aim was to assess the ability of ex vivo expanded human regulatory T cells (Treg) in modulating the rejection response against a human islet allograft in a clinically relevant model of human pancreatic islet transplantation. Methods: We studied the rejection response against allogeneic human islets in acohort of 32 immunodeficient mice which had been reconstituted with a functional human immune system. Thirteen subjects were transplanted with human islets without further immunological modification; graft survival was compared with that of thirteen subjects treated additionally with human regulatory T cells. Six controls were given a human islet transplant, but not reconstituted with human immune cells to demonstrate the functionality of the islet graft in the absence of immunological rejection. Graft function was assessed with serial blood glucose measurements, immunohistochemistry,immunoflourescence, and flow cytometry. Findings: Human islet allografts were rapidly rejected in subjects that did notreceive Treg. With Treg treatment, however, human islet allograft rejection was prevented (median survival time (MST) of > 45 days with Treg, as opposed to an MST of 23 days without Treg). Ex vivo expanded Treg homed to the lymphoid tissue draining the graft site where they suppressed the priming, activation, proliferation, and effector cytokine production of alloreactive T cells. Interpretation: These findings in a clinically relevant model of human pancreatic islet transplantation demonstrate the ability of ex vivo expanded human Treg to attenuate acute islet allograft rejection, and provide further support for their use in cellular immunotherapy.

A matching algorithm for the distribution of human pancreatic islets

The success of human pancreatic islet transplantation in a subset of type 1 diabetic patients has led to an increased demand for this tissue in both clinical and basic research, yet the availability of such preparations is limited and the quality highly variable. Under the current process of islet distribution for basic science experimentation nationwide, specialized laboratories attempt to distribute islets to one or more scientists based on a list of known investigators. This local decision making (LDM) process has been found to be ineffective and suboptimal. To alleviate these problems, a computerized Matching Algorithm for Islet Distribution (MAID) was developed to better match the functional, morphological, and quality characteristics of islet preparations to the criteria desired by basic research laboratories, i.e., requesters. The algorithm searches for an optimal combination of requesters using detailed screening, sorting, and search procedures. When applied to a data set of 68 human islet preparations distributed by the Islet Cell Resource (ICR) Center Consortium, MAID reduced the number of requesters that (a) did not receive any islets, and (b) received mis-matched shipments. These results suggest that MAID is an improved more efficient approach to the centralized distribution of human islets within a consortium setting.

Feasibility and Safety of Pancreatic Islet Transplantation in the Liver by Portal Vein Catheterization using the Transjugular Route

Feasibility and Safety of Pancreatic Islet Transplantation in the Liver by Portal Vein Catheterization using the Transjugular Route

Ex Vivo Gene Transfer for Improvement of Transplanted Pancreatic Islet Viability and Function

Human pancreatic islet transplantation has recently been shown to be successful in replacing pancreatic endocrine function into type 1 diabetic recipients. A major drawback, however, is the high amount of pancreatic ss cells required to render one single patient insulin-independent. Given the shortage of human beta cell donors, the majority of type 1 diabetic patients remain excluded from this therapeutic option. High number of islets are requested since substantial islet cell death and dysfunction occur within the first few hours and days after islet transplantation. Impaired vascularization of the engraft, the non-specific inflammatory reaction at the site of transplantation, together with the presence of active or memory autoimmune responses to islet autoantigens and allogeneic recognition contribute to apoptosis of ss cells and subsequent early graft function loss. This review will focus on ex vivo engineering of the islet graft by gene transfer to improve islet engraftment. An overview of currently used gene transfer techniques will be given and their potential will be discussed.

The current situation in human pancreatic islet transplantation: problems and prospects

In 2000, seven cases of pancreatic islet transplantation were documented by the researchers at the University of Alberta (Edmonton, Canada). The transplantation was performed using a protocol with a novel immunosuppressive regimen later named the Edmonton Protocol. The results showed that all seven patients became free of the need for insulin therapy. The success of the Edmonton Protocol has enhanced expectations for and interest in islet transplantation all over the world. Islet transplantation seems to be an almost ideal therapy for insulin-dependent patients. In our recent participation in transplant-related conferences in Europe or the USA, we have felt great enthusiasm for islet transplantation among clinicians, researchers, as well as medical staff. In Japan, the Organ Transplant Law that allows transplants from brain-dead patients was enacted in 1997. Since the passing of the law, people's interest in tissue and organ transplantation, particularly islet transplantation, has been growing. Here we present general information on islet transplantation and discuss its problems and prospects.

Using beta-cell growth factors to enhance human pancreatic Islet transplantation.

This is a particularly exciting time in the field of pancreatic islet growth, development, and survival. The recent publication of a study demonstrating that human pancreatic islet transplantation is both technically and immunologically feasible has highlighted the need for large supplies of pancreatic islets or pancreatic beta cells for larger-scale islet transplantation in patients with diabetes. This, together with a rapid expansion in the past several years of the understanding of mechanisms of islet growth, development, and survival, has accelerated and invigorated efforts to therapeutically harness the cellular mechanisms responsible for pancreatic beta-cell proliferation, survival, and development and to take advantage of this new knowledge to enhance the availability, survival, and function of pancreatic beta cells in human islet transplantation for diabetes mellitus. Here, we briefly review the confluence of events that have provided optimism and energy to the islet transplant field, and we focus on peptide growth factors that eventually may be deployed in the effort to augment islet mass and function in patients with diabetes.