Factors associated with favourable 5 year outcomes in islet transplant alone recipients with type 1 diabetes complicated by severe hypoglycaemia in the Collaborative Islet Transplant Registry

Regulating islet stress responses through CD47 activation

AIMS/HYPOTHESIS

Diabetes is a global health burden characterised by incremental beta cell loss. Islet transplantation is a recognised treatment for individuals with type 1 diabetes and hypoglycaemia unawareness but broader application is constrained by limited islet survival and function post-transplantation. The underlying molecular mechanisms that induce beta cell dysfunction and demise remain unclear, and therapeutic agents that protect against cellular loss and maintain insulin secretion are in demand as potential treatment options. CD47 is a cell surface protein implicated in cellular stress responses but its role in beta cell function remains relatively unexplored. We hypothesised that modulating CD47 expression would demonstrate a cytoprotective effect in beta cells.

METHODS

We used primary murine islets with/without genetic deletion of CD47, as well as human islets and MIN6 cells subjected to pharmacological disruption of CD47 signalling (siRNA or blocking antibody). Metabolic stress was induced in cells by exposure to hypoxia, hyperglycaemia or thapsigargin, and markers of the unfolded protein response, cell survival and insulin secretory function were assessed. Human pancreases from individuals with and without diabetes were examined for evidence of CD47 signalling.

RESULTS

Expression of CD47 and its high affinity ligand thrombospondin-1 (TSP1) was robustly upregulated by exogenous stressors. Limiting CD47 signalling improved markers of senescence, apoptosis, endoplasmic reticulum stress, unfolded protein response, self-renewal and autophagy, and maintained insulin secretory responses. We also found concurrent upregulated expression of CD47 and senescence markers in the endocrine pancreas of aged donors and those with type 2 diabetes. Both CD47 and TSP1 expression were increased in pancreases of humans with type 1 diabetes, as were plasma levels of TSP1.

CONCLUSIONS/INTERPRETATION

Our study provides key insights into the essential role of CD47 as a novel regulator of islet dysfunction, regulating cytoprotective responses to stress. CD47 may contribute to beta cell damage during the development of diabetes and failure of islet transplant function. Therefore, limiting CD47 activation may be a potential therapeutic tool in conditions where islet function is inadequate.

Advances in Islet Transplantation and the Future of Stem Cell-Derived Islets to Treat Diabetes

β-Cell replacement for type 1 diabetes (T1D) can restore normal glucose homeostasis, thereby eliminating the need for exogenous insulin and halting the progression of diabetes complications. Success in achieving insulin independence following transplantation of cadaveric islets fueled academic and industry efforts to develop techniques to mass produce β cells from human pluripotent stem cells, and these have now been clinically validated as an alternative source of regulated insulin production. Various encapsulation strategies are being pursued to contain implanted cells in a retrievable format, and different implant sites are being explored with some strategies reaching clinical studies. Stem cell lines, whether derived from embryonic sources or reprogrammed somatic cells, are being genetically modified for designer features, including immune evasiveness to enable implant without the use of chronic immunosuppression. Although hurdles remain in optimizing large-scale manufacturing, demonstrating efficacy, durability, and safety, products containing stem cell-derived β cells promise to provide a potent treatment for insulin-dependent diabetes.

β-Cell Secretory Capacity Predicts Metabolic Outcomes Over 6 Years After Human Islet Transplantation

Transplanted islet functional β-cell mass is measured by β-cell secretory capacity derived from the acute insulin response to glucose-potentiated arginine (AIRpot); however, data are limited beyond 1 year posttransplantation for individuals with type 1 diabetes. We evaluated changes in β-cell secretory capacity in a single-center longitudinal analysis and examined relationships with measures of islet cell hormone metabolism and clinical measures of graft function (mixed-meal tolerance test [MMTT] C-peptide, BETA-2 score, and continuous glucose monitoring [CGM]). Eleven individuals received purified human pancreatic islets over one or two intraportal infusions to achieve insulin independence and were observed over a median of 6 (interquartile range 5-7) years. β-Cell secretory capacity remained stable over 3 years before declining. Fasting glucagon and proinsulin secretory ratios under glucose potentiation were inversely correlated with AIRpot. A functional β-cell mass of 40% normal predicted insulin independence and was strongly predicted by ratio of MMTT C-peptide to glucose and BETA-2 score. A functional β-cell mass of >20% normal predicted excellent glycemic outcomes, including ≤1% time in range <60 mg/dL, ≤2% time in range >180 mg/dL, and ≥90% time in range 70-180 mg/dL. β-Cell replacement approaches should target a functional β-cell mass >40% normal to provide sufficient islet reserve for sustained insulin independence. Ratio of MMTT C-peptide to glucose and BETA-2 score can inform changes in functional β-cell mass in the clinical setting.

ARTICLE HIGHLIGHTS

Islet Transplantation Versus Standard of Care for Type 1 Diabetes Complicated by Severe Hypoglycemia From the Collaborative Islet Transplant Registry and the T1D Exchange Registry

OBJECTIVE

Islet transplantation was recently approved by the U.S. Food and Drug Administration for adults with type 1 diabetes complicated by recurrent severe hypoglycemia events (SHEs). We sought to understand the long-term benefit for glycemic control and risk of immunosuppression to kidney function associated with islet transplantation compared with ongoing standard of care.

RESEARCH DESIGN AND METHODS

We performed a case-control analysis of prospectively collected data from patients in the Collaborative Islet Transplant Registry (CITR) with at least one SHE in the year (2000-2014) before transplantation (case subjects) and compared them with data from patients in the T1D Exchange (T1DX) Registry with at least one SHE in the year (2010-2012) before enrollment (control subjects), with both cohorts observed over 5 years. SHEs were restricted to those resulting in seizure or loss of consciousness.

RESULTS

Case subjects from CITR (n = 71) compared with control subjects from T1DX (n = 213) more often achieved the primary outcome of HbA1c <7.0% and absence of an SHE (71-80% vs. 21-33% over 5 years; P < 0.001) and the outcome of HbA1c ≤6.5% and absence of an SHE (60-75% vs. 10-20%; P < 0.001) while requiring significantly less insulin (majority in CITR were insulin independent). Kidney function, measured by estimated glomerular filtration rate, declined from baseline to a greater extent in CITR than in T1DX (-8.8 to -20 vs. -1.3 to -6.5 mL ⋅ min-1 ⋅ 1.73 m-2 over 5 years; P < 0.001).

CONCLUSIONS

Islet transplantation for adults with type 1 diabetes complicated by SHEs results in near-normal glycemic control in the absence of SHEs more often than observed with standard of care, but at the cost of greater reduction in kidney function.

Recreating the Endocrine Niche: Advances in Bioengineering the Pancreas

Intrahepatic islet transplantation is a promising strategy for β-cell replacement therapy in the treatment of Type 1 Diabetes. However, several obstacles hinder the long-term efficacy of this therapy. A major challenge is the scarcity of donor organs. During the isolation process, islets are disconnected from their extracellular matrix (ECM) and vasculature, leading to significant loss due to anoikis and hypoxia. Additionally, inflammatory and rejection reactions further compromise islet survival and engraftment success. Extensive efforts are being made to improve the efficacy of islet transplantation. These strategies include promoting revascularization and ECM support through bioengineering techniques, exploring alternative sources of insulin-secreting cells, and providing immunomodulation for the graft. Despite these advancements, a significant gap remains in integrating these strategies into a cohesive approach that effectively replicates the native endocrine environment. Specifically, the lack of comprehensive methods to address both the structural and functional aspects of the endocrine niche limits reproducibility and clinical translation. Therefore, bioengineering an endocrine pancreas must aim to recreate the endocrine niche to achieve lifelong efficacy and insulin independence. This review discusses various strategies developed to produce the building blocks for generating a vascularized, immune-protected insulin-secreting construct, emphasizing the importance of the endocrine niche's composition and function.

Long-term outcomes of pancreatic islet transplantation alone in type 1 diabetes: a 20-year single-centre study in Italy

BACKGROUND

Islet transplantation has the potential to cure type 1 diabetes by restoring endogenous insulin production. However, its success relies on balancing improved glycaemic control with the risks of immunosuppressive therapy. This study aimed to evaluate long-term outcomes of islet transplantation alone for type 1 diabetes, focusing on the effects of islet mass and immunosuppressive regimens on graft survival and insulin independence, and weighing glycaemic control benefits against the risks of immunosuppressive therapy.

METHODS

This cohort study retrospectively analysed individuals aged 18-67 years with type 1 diabetes who received intraportal islet transplantation alone at IRCCS Ospedale San Raffaele, Milan, Italy. Inclusion criteria comprised adults with type 1 diabetes diagnosed before the age of 55 years with severe recurrent hypoglycaemia or glycaemic instability. Major exclusion criteria included a HbA1c of more than 12·5%, a BMI of more than 30 kg/m2, and insulin requirements exceeding 1·2 IU/kg per day, along with contraindications to immunosuppressive therapy. Participants were recruited from the hospital's islet transplant registry. Follow-up was conducted through regular clinical visits, with data collected retrospectively. Outcomes assessed included patient survival, graft survival, insulin independence, glycaemic control, and adverse events. Data were analysed using an intention-to-treat method, mixed-effects models, Kaplan-Meier estimates, and Cox and logistic regression to identify factors linked to metabolic success and reduced risks.

FINDINGS

79 patients underwent intrahepatic or intraportal islet transplantation alone between Feb 16, 2001, and June 1, 2023, and received a total of 159 islet infusions, with a median total islet mass of 9637 islet equivalents (IEQ) per kg. Complications were infrequent and mostly involved minor bleeding, with only 3% (two of 79) of patients requiring surgical intervention. Glycaemic control improved significantly after infusion, with a reduction of HbA1c by -10·04 mmol/mol (-13·63 to -6·46), and a decrease in daily insulin requirements by -13·35 units per day (-17·04 to -9·65). The intention-to-treat analysis showed a median graft survival (fasting C peptide ≥0·3 ng/mL) of 3·9 years (95% CI 1·6 to 6·2) and 44% (35/79) insulin independence for a median of 6 years (95% CI 2·88 to 9·08). Patients receiving more than 10 000 IEQ/kg with BAS, FK506, and Rapa therapy had a median graft survival of 9·7 years (3·1-16·0) and 73% (16 of 22) insulin independence. Kaplan-Meier estimates indicated graft survival rates of 86% at 1 year, 65% at 5 years, 47% at 10 years, 47% at 15 years, and 40% at 20 years. Overall survival was 92% (73 of 79) over a median follow-up of 13·1 years, with a 20-year survival probability of 84%. Adverse events related to immunosuppressive therapy were reported in 44% (35 of 79) of patients, with allosensitisation rates increasing from 6% at baseline to 42% after therapy discontinuation.

INTERPRETATION

This analysis of a large islet transplantation alone cohort provides valuable insights into factors influencing outcomes and highlights potential risks, supporting informed clinical decision making and the optimisation of future β-cell replacement strategies.

FUNDING

None.

Efficacy and Safety of Allogeneic Islet Transplantation Demonstrated by a Multicenter Clinical Trial in Japan

Background

Islet transplantation in type 1 diabetes mellitus restores endogenous insulin secretion and hypoglycemia awareness. Although high-quality prospective clinical trials have demonstrated the efficacy of islet transplantation, reports on the clinical outcomes in Asia remain scarce. Therefore, we conducted a clinical trial in Japan to verify the effectiveness of islet transplantation.

Methods

This multicenter, single-arm study aimed to evaluate the clinical efficacy and safety of immunosuppressive therapy for allogeneic islet transplantation. The immunosuppressive regimens included antithymocyte globulin, calcineurin inhibitors, and mycophenolate mofetil. The primary endpoint was a glycated hemoglobin level of <7.4% on day 365 and the absence of severe hypoglycemic events from 1 mo to 1 y after the first transplantation.

Results

Eight recipients with evaluation data obtained 1 y after the initial transplantation were included in the efficacy analysis. Of the 8 recipients, 3, 3, and 2 recipients received 1, 2, and 3 islet infusions, respectively. Six recipients (75%) achieved the primary endpoint. The median glycated hemoglobin levels declined from an initial 7.3% to 6.3% and 6.1% on days 375 and 730, respectively, with related improvements in hypoglycemia awareness and glucose variability. No complications associated with intraportal transplantation, such as intraperitoneal hemorrhage or portal vein embolism, were observed.

Conclusions

Islet transplantation provided near-normal glycemic control and protection against severe hypoglycemic events in patients with type 1 diabetes mellitus in this Japanese cohort. Future studies are needed to confirm whether long-term graft survival can be achieved and whether it is possible to prevent the progression of diabetic complications.

Harnessing cellular therapeutics for type 1 diabetes mellitus: progress, challenges, and the road ahead

Type 1 diabetes mellitus (T1DM) is a growing global health concern that affects approximately 8.5 million individuals worldwide. T1DM is characterized by an autoimmune destruction of pancreatic β cells, leading to a disruption in glucose homeostasis. Therapeutic intervention for T1DM requires a complex regimen of glycaemic monitoring and the administration of exogenous insulin to regulate blood glucose levels. Advances in continuous glucose monitoring and algorithm-driven insulin delivery devices have improved the quality of life of patients. Despite this, mimicking islet function and complex physiological feedback remains challenging. Pancreatic islet transplantation represents a potential functional cure for T1DM but is hindered by donor scarcity, variability in harvested cells, aggressive immunosuppressive regimens and suboptimal clinical outcomes. Current research is directed towards generating alternative cell sources, improving transplantation methods, and enhancing cell survival without chronic immunosuppression. This Review maps the progress in cell replacement therapies for T1DM and outlines the remaining challenges and future directions. We explore the state-of-the-art strategies for generating replenishable β cells, cell delivery technologies and local targeted immune modulation. Finally, we highlight relevant animal models and the regulatory aspects for advancing these technologies towards clinical deployment.

Impact of Tacrolimus, Sirolimus, Age, and Body Mass Index on the Occurrence of Skin Cancer and Islet Dysfunction After Transplantation

Herein, we characterized the percentage of tacrolimus to the combined sirolimus and tacrolimus trough levels (tacrolimus %) observed during islet transplant-associated immune suppression therapy with post-transplant skin cancer. Although trough levels of tacrolimus and sirolimus were not different (P = 0.79, 0.73, respectively), high tacrolimus % resulted in a 1.32-fold increase in skin cancer odds when adjusting for age, sex, body mass index (BMI), and use of mycopheonlate mofetil (MMF; p = 0.039). Skin cancer patients were likely to have been older but not differ significantly (mean difference 12 years, P = 0.056), but age was significantly associated with a 1.22-fold increase in adjusted skin cancer odds (P = 0.046). BMI was inversely associated with skin cancer, with an adjusted odds ratio (OR) of 0.40 (P = 0.022). High tacrolimus % (>35) resulted in a 4.6-fold increase in skin cancer frequency, whereas sirolimus above 75% of the combined therapy led to a 5.2-fold increase in islet graft dysfunction (IGD) events/year. By calculating the maximum safe exposure (MSE) to tacrolimus % according to patient age and BMI, we found that cumulative months spent above MSE was predictive of skin cancer (1.20-fold increase, P = 0.003). Individuals exceeding the MSE for 1 year were 9.2 times more likely to develop skin cancer (P = 0.008). Results suggest that strategies targeting immunosuppression ratios based on age and BMI may minimize cancer risk while improving graft survival and function.

Identifying Promising Immunomodulators for Type 1 Diabetes (T1D) and Islet Transplantation

Type 1 diabetes (T1D) is an autoimmune chronic disorder that damages beta cells in the pancreatic islets of Langerhans and results in hyperglycemia due to the loss of insulin. Exogenous insulin therapy can save lives but does not stop disease progression. Thus, an effective therapy may require beta cell restoration and suppression of the autoimmune response. However, currently, there are no treatment options available that can reverse T1D. Within the National Clinical Trial (NCT) database, a majority of over 3000 trials to treat T1D are devoted to insulin therapy. This review focuses on noninsulin pharmacological therapies, specifically immunomodulators. Many investigational new drugs fall under this category, such as the recently FDA-approved CD3 monoclonal antibody teplizumab to delay the onset of T1D. In total, we identified 39 different immunomodulatory investigational drugs. FDA-approved teplizumab for Stage 2 T1D is discussed along with other immunomodulators that have been tested in Phase 3 clinical trials or higher, including otelixizumab (another anti-CD3 monoclonal antibody), daclizumab (an anti-CD25 monoclonal antibody), ladarixin (CXCR1/2 inhibitor), and antithymocyte globulin (ATG). Immunomodulators also play roles in islet transplantation and cellular therapies like FDA-approved Lantidra. Several immunomodulators involved in Phase 3 clinical studies of islet transplantation are also discussed, including alemtuzumab, basiliximab, etanercept, and reparixin, some already FDA-approved for other uses. These include alemtuzumab, basiliximab, etanercept, and reparixin, some of which have been FDA-approved for other uses. This review provides background, mechanism of action, results of completed trials, and adverse effects as well as details regarding ongoing clinical trials for each of these immunomodulators. Trial Registration: ClinicalTrials.gov identifier: NCT03875729, NCT01030861, NCT00129259, NCT00385697, NCT01280682; NCT03929601, NCT04598893, NCT05757713, NCT00678886, NCT01123083, NCT00064714, NCT00468117, NCT04628481, NCT01106157, NCT02215200, NCT00331162, NCT00679042, NCT01220856, NCT01817959.

Current Challenges in Pancreas and Islet Transplantation: A Scoping Review

Type 1 diabetes mellitus is an autoimmune condition characterized by the destruction of pancreatic β-cells, necessitating insulin therapy to prevent life-threatening complications such as diabetic ketoacidosis. Despite advancements in glucose monitoring and pharmacological treatments, managing this disease remains challenging, often leading to long-term complications and psychological burdens, including diabetes distress. Advanced treatment options, such as whole-pancreas transplantation and islet transplantation, aim to restore insulin production and improve glucose control in selected patients with diabetes. The risk of transplant rejection necessitates immunosuppressive therapy, which increases susceptibility to infections and other adverse effects. Additionally, surgical complications, including infection and bleeding, are significant concerns, particularly for whole-pancreas transplantation. Recently, stem cell-derived therapies for type 1 diabetes have emerged as a promising alternative, offering potential solutions to overcome the limitations of formerly established transplantation methods. The purpose of this scoping review was to: (1) summarize the current evidence on achieved insulin independence following various transplantation methods of insulin-producing cells in patients with type 1 diabetes; (2) compare insulin independence rates among whole-pancreas transplantation, islet cell transplantation, and stem cell transplantation; and (3) identify limitations, challenges and potential future directions associated with these techniques. We systematically searched three databases (PubMed, Scopus, and Web of Science) from inception to November 2024, focusing on English-language, peer-reviewed clinical studies. The search terms used were 'transplantation' AND 'type 1 diabetes' AND 'insulin independence'. Studies were included if they reported on achieved insulin independence, involved more than 10 patients with type 1 diabetes, and had a mean follow-up period of at least one year. Reviewers screened citations and extracted data on transplant type, study population size, follow-up duration, and insulin independence rates. We identified 1380 papers, and after removing duplicates, 705 papers remained for title and abstract screening. A total of 139 English-language papers were retrieved for full-text review, of which 48 studies were included in this review. The findings of this scoping review indicate a growing body of literature on transplantation therapy for type 1 diabetes. However, significant limitations and challenges, like insufficient rates of achieved insulin independence, risks related to immunosuppression, malignant diseases, and ethical issues remain with each of the established techniques, highlighting the need for innovative approaches such as stem cell-derived islet transplantation to promote β-cell regeneration and protection.

A differentiation protocol for generating pancreatic delta cells from human pluripotent stem cells

In this protocol, we detail a seven-stage differentiation methodology for generating pancreatic delta cells (SC-delta cells) from human pluripotent stem cells (hPSCs). In the first step, definitive endoderm is generated by activin A and CHIR99021, followed by induction of primitive gut tube and posterior foregut by treatment with FGF7, SANT1, LDN193189, PdBU, and retinoic acid (RA). The subsequent endocrine generation and directed SC-delta cell induction is achieved by a combined treatment of the FGF7 with FGF2 during stage 4 and 5, together with RA, XXI, ALK5 inhibitor II, SANT1, Betacellulin and LDN193189. The planar cultivation is converted to a suspended system after stage 5, allowing cells to aggregate into delta cell-containing spheroids. The differentiation takes approximately 4-5 weeks for delta cell generation and an additional 1-2 weeks for cell expansion and evaluation. We believe that this amenable and simplified protocol can provide a stable source of SC-delta cells from efficient differentiation, facilitating further investigation of the physiological role of delta cells as well as refinement of islet cell therapeutic strategies.

Functional maturation and longitudinal imaging of intraportal neonatal porcine islet grafts in genetically diabetic pigs

Allogeneic intraportal islet transplantation (ITx) has become an established treatment for patients with poorly controlled type 1 diabetes. However, the loss of viable beta-cell mass after transplantation remains a major challenge. Therefore, noninvasive imaging methods for long-term monitoring of the transplant fate are required. In this study, [68Ga]Ga-DOTA-exendin-4 positron emission tomography/computed tomography (PET/CT) was used for repeated monitoring of allogeneic neonatal porcine islets (NPI) after intraportal transplantation into immunosuppressed genetically diabetic pigs. NPI transplantation (3320-15,000 islet equivalents per kg body weight) led to a reduced need for exogenous insulin therapy and finally normalization of blood glucose levels in 3 out of 4 animals after 5 to 10 weeks. Longitudinal PET/CT measurements revealed a significant increase in standard uptake values in graft-bearing livers. Histologic analysis confirmed the presence of well-engrafted, mature islet clusters in the transplanted livers. Our study presents a novel large animal model for allogeneic intraportal ITx. A relatively small dose of NPIs was sufficient to normalize blood glucose levels in a clinically relevant diabetic pig model. [68Ga]Ga-DOTA-exendin-4 PET/CT proved to be efficacious for longitudinal monitoring of islet transplants. Thus, it could play a crucial role in optimizing ITx as a curative therapy for type 1 diabetes.

Pancreatic islet transplantation: current advances and challenges

Diabetes is a prevalent chronic disease that traditionally requires severe reliance on medication for treatment. Oral medication and exogenous insulin can only temporarily maintain blood glucose levels and do not cure the disease. Most patients need life-long injections of exogenous insulin. In recent years, advances in islet transplantation have significantly advanced the treatment of diabetes, allowing patients to discontinue exogenous insulin and avoid complications.Long-term follow-up results from recent reports on islet transplantation suggest that they provide significant therapeutic benefit although patients still require immunotherapy, suggesting the importance of future transplantation strategies. Although organ shortage remains the primary obstacle for the development of islet transplantation, new sources of islet cells, such as stem cells and porcine islet cells, have been proposed, and are gradually being incorporated into clinical research. Further research on new transplantation sites, such as the subcutaneous space and mesenteric fat, may eventually replace the traditional portal vein intra-islet cell infusion. Additionally, the immunological rejection reaction in islet transplantation will be resolved through the combined application of immunosuppressant agents, islet encapsulation technology, and the most promising mesenchymal stem cells/regulatory T cell and islet cell combined transplantation cell therapy. This review summarizes the progress achieved in islet transplantation, and discusses the research progress and potential solutions to the challenges faced.

Long-term efficacy of encapsulated xenogeneic islet transplantation: Impact of encapsulation techniques and donor genetic traits

AIMS/INTRODUCTION

To investigate the long-term efficacy of various encapsulated xenogeneic islet transplantation, and to explore the impact of different donor porcine genetic traits on islet transplantation outcomes.

MATERIALS AND METHODS

Donor porcine islets were obtained from wild-type, α1,3-galactosyltransferase knockout (GTKO) and GTKO with overexpression of membrane cofactor protein genotype. Naked, alginate, alginate-chitosan (AC), alginate-perfluorodecalin (A-PFD) and AC-perfluorodecalin (AC-PFD) encapsulated porcine islets were transplanted into diabetic mice.

RESULTS

In vitro assessments showed no differences in the viability and function of islets across encapsulation types and donor porcine islet genotypes. Xenogeneic encapsulated islet transplantation with AC-PFD capsules showed the most favorable long-term outcomes, maintaining normal blood glucose levels for 180 days. A-PFD capsules showed comparable results to AC-PFD capsules, followed by AC capsules and alginate capsules. Conversely, blood glucose levels in naked islet transplantation increased to >300 mg/dL within a week after transplantation. Naked islet transplantation outcomes showed no improvement based on donor islet genotype. However, alginate or AC capsules showed delayed increases in blood glucose levels for GTKO and GTKO with overexpression of membrane cofactor protein porcine islets compared with wild-type porcine islets.

CONCLUSION

The AC-PFD capsule, designed to ameliorate both hypoxia and inflammation, showed the highest long-term efficacy in xenogeneic islet transplantation. Genetic modifications of porcine islets with GTKO or GTKO with overexpression of membrane cofactor protein did not influence naked islet transplantation outcomes, but did delay graft failure when encapsulated.

Legal and Regulatory Challenges for Emerging Regenerative Medicine Solutions for Diabetes

Regenerative medicine solutions for type 1 diabetes are a rapidly developing field of medical technology. To date, these solutions have been principally cell-based treatments and at present, in Europe, these therapies are regulated under European Union regulations for advanced therapy medicinal products. But now, new emerging technology combining cellular therapy with medical devices is under development. The potential of this novel hybrid model to create a bioartificial pancreas to treat type 1 diabetes is tantalizing. However, incorporating medical devices creates a further layer of regulatory complexity. This article seeks to expose the complexity of this legal and regulatory landscape and demonstrate how evolving technology could challenge the entire existing legal paradigm. We start by summarizing the status of the only established cell-based therapy-transplantation. We set out the regulation of cellular therapies, their classification, and the role of statutory bodies. We examine the bottleneck of therapies moving from bench to bedside, and we consider the additional challenges of products, which use a combination of cells and medical devices. Finally, we argue that for the potential of this rapidly growing area of technology to be realized a seismic shift in how we regulate frontier cellular therapies will be required.

The Adrenal Gland and Pancreatic Islets - A Beneficial Endocrine Alliance

Intraportal islet transplantation in patients with type 1 diabetes enables restoration of glucose-regulated insulin secretion. However, several factors hamper a widespread application and long-term success: chronic hypoxia, an inappropriate microenvironment and suppression of regenerative and proliferative potential by high local levels of immunosuppressive agents. Therefore, the identification of alternative and superior transplant sites is of major scientific and clinical interest. Here, we aim to evaluate the adrenal as an alternative transplantation site. The adrenal features a particular microenvironment with extensive vascularization, anti-apoptotic and pro-proliferative, anti-inflammatory and immunosuppressive effects. To validate this novel transplantation site, an in vitro co-culture system of adrenal cells and pancreatic islets was established and viability, islet survival, functional potency and antioxidative defense capacity were evaluated. For in vivo validation, an immune-deficient diabetic mouse model for intra-adrenal islet transplantation was applied. The functional capacity of intra-adrenally grafted islets to reverse diabetes was compared to a standard islet transplant model and measures of engraftment such as vascular integration were evaluated. The presence of adrenal cells positively impacted on cell metabolism and oxidative stress. Following transplantation, we could demonstrate enhanced islet function in comparison to standard models with improved engraftment and superior re-vascularization. This experimental approach allows for novel insights into the interaction of endocrine systems and may open up novel strategies for islet transplantation augmented through the bystander effect of other endocrine cells or the active factors secreted by adrenal cells modulating the microenvironment.

Immunoprotection of cellular transplants for autoimmune type 1 diabetes through local drug delivery

Type 1 diabetes mellitus (T1DM) is an autoimmune condition that results in the destruction of insulin-secreting β cells of the islets of Langerhans. Allogeneic islet transplantation could be a successful treatment for T1DM; however, it is limited by the need for effective, permanent immunosuppression to prevent graft rejection. Upon transplantation, islets are rejected through non-specific, alloantigen specific, and recurring autoimmune pathways. Immunosuppressive agents used for islet transplantation are generally successful in inhibiting alloantigen rejection, but they are suboptimal in hindering non-specific and autoimmune pathways. In this review, we summarize the challenges with cellular immunological rejection and therapeutics used for islet transplantation. We highlight agents that target these three immune rejection pathways and how to package them for controlled, local delivery via biomaterials. Exploring macro-, micro-, and nano-scale immunomodulatory biomaterial platforms, we summarize their advantages, challenges, and future directions. We hypothesize that understanding their key features will help identify effective platforms to prevent islet graft rejection. Outcomes can further be translated to other cellular therapies beyond T1DM.

Safety and Efficacy of Sustained Automated Insulin Delivery Compared With Sensor and Pump Therapy in Adults With Type 1 Diabetes at High Risk for Hypoglycemia: A Randomized Controlled Trial

OBJECTIVE

Assess the safety and efficacy of automated insulin delivery (AID) in adults with type 1 diabetes (T1D) at high risk for hypoglycemia.

RESEARCH DESIGN AND METHODS

Participants were 72 adults with T1D who used an insulin pump with Clarke Hypoglycemia Perception Awareness scale score >3 and/or had severe hypoglycemia during the previous 6 months confirmed by time below range (TBR; defined as sensor glucose [SG] reading <70 mg/dL) of at least 5% during 2 weeks of blinded continuous glucose monitoring (CGM). Parallel-arm, randomized trial (2:1) of AID (Tandem t:slim ×2 with Control-IQ technology) versus CGM and pump therapy for 12 weeks. The primary outcome was TBR change from baseline. Secondary outcomes included time in target range (TIR; 70-180 mg/dL), time above range (TAR), mean SG reading, and time with glucose level <54 mg/dL. An optional 12-week extension with AID was offered to all participants.

RESULTS

Compared with the sensor and pump (S&P), AID resulted in significant reduction of TBR by -3.7% (95% CI -4.8, -2.6), P < 0.001; an 8.6% increase in TIR (95% CI 5.2, 12.1), P < 0.001; and a -5.3% decrease in TAR (95% CI -87.7, -1.8), P = 0.004. Mean SG reading remained similar in the AID and S&P groups. During the 12-week extension, the effects of AID were sustained in the AID group and reproduced in the S&P group. Two severe hypoglycemic episodes occurred using AID.

CONCLUSIONS

In adults with T1D at high risk for hypoglycemia, AID reduced the risk for hypoglycemia more than twofold, as quantified by TBR, while improving TIR and reducing hyperglycemia. Hence, AID is strongly recommended for this specific population.

The Current Status of Allogenic Islet Cell Transplantation

Type 1 Diabetes (T1D) is an autoimmune destruction of pancreatic beta cells. The development of the Edmonton Protocol for islet transplantation in 2000 revolutionized T1D treatment and offered a glimpse at a cure for the disease. In 2022, the 20-year follow-up findings of islet cell transplantation demonstrated the long-term safety of islet cell transplantation despite chronic immunosuppression. The Edmonton Protocol, however, remains limited by two obstacles: scarce organ donor availability and risks associated with chronic immunosuppression. To overcome these challenges, the search has begun for an alternative cell source. In 2006, pluripotency genomic factors, coined "Yamanaka Factors," were discovered, which reprogram mature somatic cells back to their embryonic, pluripotent form (iPSC). iPSCs can then be differentiated into specialized cell types, including islet cells. This discovery has opened a gateway to a personalized medicine approach to treating diabetes, circumventing the issues of donor supply and immunosuppression. In this review, we present a brief history of allogenic islet cell transplantation from the early days of pancreatic remnant transplantation to present work on encapsulating stem cell-derived cells. We review data on long-term outcomes and the ongoing challenges of allogenic islet cell and stem cell-derived islet cell transplant.

Association between primary graft function and 5-year outcomes of islet allogeneic transplantation in type 1 diabetes: a retrospective, multicentre, observational cohort study in 1210 patients from the Collaborative Islet Transplant Registry

BACKGROUND

Allogeneic islet transplantation is a validated therapy in type 1 diabetes; however, there is decline of transplanted islet graft function over time and the mechanisms underlying this decline are unclear. We evaluated the distinct association between primary graft function (PGF) and 5-year islet transplantation outcomes.

METHODS

In this retrospective, multicentre, observational cohort study, we enrolled all patients from the Collaborative Islet Transplant Registry who received islet transplantation alone (ITA recipients) or islet-after-kidney transplantation (IAK recipients) between Jan 19, 1999, and July 17, 2020, with a calculable PGF (exposure of interest), measured 28 days after last islet infusion with a validated composite index of islet graft function (BETA-2 score). The primary outcome was cumulative incidence of unsuccessful islet transplantation, defined as an HbA1c of 7·0% (53 mmol/mol) or higher, or severe hypoglycaemia (ie, requiring third-party intervention to correct), or a fasting C-peptide concentration of less than 0·2 ng/mL. Secondary outcomes were graft exhaustion (fasting C-peptide <0·3 ng/mL); inadequate glucose control (HbA1c ≥7·0% [53 mmol/mol] or severe hypoglycaemia); and requirement for exogenous insulin therapy (≥14 consecutive days). Associations between PGF and islet transplantation outcomes were explored with a competing risk analysis adjusted for all covariates suspected or known to affect outcomes. A predictive model based on PGF was built and internally validated by using bootstraps resampling method.

FINDINGS

In 39 centres worldwide, we enrolled 1210 patients with a calculable PGF (of those without missing data, mean age 47 years [SD 10], 712 [59·5%] were female, and 865 (97·9%) were White), who received a median of 10·8 thousand islet-equivalents per kg of bodyweight (IQR 7·4-13·5). 986 (82·4%) were ITA recipients and 211 (17·6%) were IAK recipients. Of 1210 patients, 452 (37·4%) received a single islet infusion and 758 (62·6%) received multiple islet infusions. Mean PGF was 14·3 (SD 8·8). The 5-year cumulative incidence of unsuccessful islet transplantation was 70·7% (95% CI 67·2-73·9), and was inversely and linearly related to PGF, with an adjusted subhazard ratio (sHR) of 0·77 (95% CI 0·72-0·82) per 5-unit increase of BETA-2 score (p<0·0001). Secondary endpoints were similarly related to PGF. The model-adjusted median C-statistic values of PGF for predicting 5-year cumulative incidences of unsuccessful islet transplantation, graft exhaustion, inadequate glucose control, and exogenous insulin therapy were 0·70 (range 0·69-0·71), 0·76 (0·74-0·77), 0·65 (0·64-0·66), and 0·72 (0·71-0·73), respectively.

INTERPRETATION

This global multicentre study reports a linear and independent association between PGF and 5-year clinical outcomes of islet transplantation. The main study limitations are its retrospective design and the absence of analysis of complications.

FUNDING

Public Health Service Research, National Institutes of Health, Juvenile Diabetes Research Foundation International, Agence National de la Recherche, Fondation de l'Avenir, and Fonds de Dotation Line Renaud-Loulou Gasté.

Developments in stem cell-derived islet replacement therapy for treating type 1 diabetes

The generation of islet-like endocrine clusters from human pluripotent stem cells (hPSCs) has the potential to provide an unlimited source of insulin-producing β cells for the treatment of diabetes. In order for this cell therapy to become widely adopted, highly functional and well-characterized stem cell-derived islets (SC-islets) need to be manufactured at scale. Furthermore, successful SC-islet replacement strategies should prevent significant cell loss immediately following transplantation and avoid long-term immune rejection. This review highlights the most recent advances in the generation and characterization of highly functional SC-islets as well as strategies to ensure graft viability and safety after transplantation.

HLA-B Matching Prolongs Allograft Survival in Islet Cell Transplantation

Islet cell transplantation (ITx) is an effective therapeutic approach for selected patients with type 1 diabetes with hypoglycemia unawareness and severe hypoglycemia events. In organ transplantation, human leukocyte antigen (HLA) mismatching between donor and recipient negatively impacts transplant outcomes. We aimed to determine whether HLA matching has an impact on islet allograft survival. Forty-eight patients were followed up after islet transplantation at our institution from 2000 to 2020 in a retrospective cohort. Patients underwent intrahepatic ITx or laparoscopic omental approach. Immunosuppression was dependent upon the protocol. We analyzed HLA data restricted to A, B, and DR loci on allograft survival using survival and subsequent multivariable analyses. Patients were aged 42.8 ± 8.4 years, and 64.3% were female. Diabetes duration was 28.6 ± 11.6 years. Patients matching all three HLA loci presented longer graft survival (P = 0.030). Patients with ≥1 HLA-B matching had longer graft survival compared with zero matching (P = 0.025). The number of HLA-B matching was positively associated with time of graft survival (Spearman's rho = 0.590; P = 0.034). Analyses adjusted for confounders showed that ≥1 matching for HLA-B decreased the risk of allograft failure (P = 0.009). Our data suggest that HLA-B matching between recipients and donors improved islet allograft survival. Matching all three HLA loci (A, B, and DR) was also associated with prolonged islet allograft survival. Prospective studies and a larger sample size are warranted to validate our findings.