Bioengineering and omics approaches for Type 1 diabetes practical research: advancements and constraints

Insulin dependency arises from autoimmunity that targets the β cells of the pancreas, resulting in Type 1 diabetes (T1D). Despite the fact that T1D patients require insulin for survival, insulin does not provide a cure for this disease or prevent its complications. Despite extensive genetic, molecular, and cellular research on T1D over the years, the translation of this understanding into effective clinical therapies continues to pose a significant obstacle. It is therefore difficult to develop effective clinical treatment strategies without a thorough understanding of disease pathophysiology. Pancreatic tissue bioengineering models of human T1D offer a valuable approach to examining and controlling islet function while tackling various facets of the condition. And in recent years, due to advances in high-throughput omics analysis, the genotypic and molecular profiles of T1D have become finer tuned. The present article will examine recent progress in these areas, along with their utilization and constraints in the realm of T1D.

Association between weekend catch-up sleep and chronic kidney disease: insights from NHANES 2017-2020

OBJECTIVE

This study aimed to explore the association between weekend catch-up sleep (WCS) and chronic kidney disease (CKD) in American adults.

METHODS

Utilizing data from the National Health and Nutrition Examination Survey (NHANES) spanning 2017 to 2020, this study encompassed 4,934 individuals aged 20 years and above. We assessed the risk of CKD in relation to WCS. To evaluate CKD risk across various WCS durations, participants were categorized into four groups based on WCS length: < 1 h (reference group), ≥ 1 h and < 2 h, ≥ 2 h and < 3 h, and ≥ 3 h.

RESULTS

In the fully adjusted multivariate logistic regression model, the odds ratio (OR) of CKD to WCS response was 0.86 (95% CI = 0.61-1.22; p = 0.31). In addition, only CKD was significantly associated with WCS duration between 2-3 h (OR = 0.44, 95% CI = 0.21-0.88, p = 0.03). Subgroup analyses showed stronger negative associations (p < 0.05) for men and women with a WCS of 2-3 h, adults under 60 years of age with a WCS of 2-3 h, those with less than 1 h of catch-up sleep on weekends and a body mass index (BMI) of 25-29.9, those with a BMI of less than 25 or greater than or equal to 30 with a WCS of 2-3 h, and those with less than 7 h of sleep on weekdays and 2-3 h of catch-up sleep on weekends.

CONCLUSION

Our findings suggest that when weekday sleep duration is < 7 h, WCS in 2-3 h is strongly associated with a lower prevalence of CKD.

Magnesium-assisted hydrogen improves isoproterenol-induced heart failure

Heart failure (HF) is a leading cause of mortality among patients with cardiovascular disease and is often associated with myocardial apoptosis and endoplasmic reticulum stress (ERS). While hydrogen has demonstrated potential in reducing oxidative stress and ERS, recent evidence suggests that magnesium may aid in hydrogen release within the body, further enhancing these protective effects. This study aimed to investigate the cardioprotective effects of magnesium in reducing apoptosis and ERS through hydrogen release in a rat model of isoproterenol (ISO)-induced HF. Magnesium was administered orally to ISO-induced HF rats, which improved cardiac function, reduced myocardial fibrosis and cardiac hypertrophy, and lowered the plasma levels of creatine kinase-MB, cardiac troponin-I, and N-terminal B-type natriuretic peptide precursor in ISO-induced HF rats. It also inhibited cardiomyocyte apoptosis by upregulating B-cell lymphoma-2, downregulating Bcl-2-associated X protein, and suppressing ERS markers (glucose-related protein 78, activating transcription factor 4, and C/EBP-homologous protein). Magnesium also elevated hydrogen levels in blood, plasma, and cardiac tissue, as well as in artificial gastric juice and pure water, where hydrogen release lasted for at least four hours. Additionally, complementary in vitro experiments were conducted using H9C2 cardiomyocyte injury models, with hydrogen-rich culture medium as the intervention. Hydrogen-rich culture medium improved the survival and proliferation of ISO-treated H9C2 cells, reduced the cell surface area, inhibited apoptosis, and downregulated ERS pathway proteins. However, the protective effects of hydrogen were negated by tunicamycin (an inducer of ERS) in H9C2 cells. In conclusion, magnesium exerts significant cardioprotection by mitigating ERS and apoptosis through hydrogen release effects in ISO-induced HF.

The effects of free fatty acid-free bovine serum albumin and palmitate on pancreatic β-cell function

Pancreatic β-cells release insulin in response to fluctuations in plasma glucose, amino acids, and free fatty acids (FFA). Clonal cell lines and isolated islets serve as essential early models for studying the impact of nutrients and evaluating potential therapies to address β-cell dysfunction. Acute and chronic changes in FFA levels have been shown to have positive and negative effects on β-cell function both in vivo and in vitro. A key problem in comparing islet lipid studies from different laboratories is that a wide variety of methods are used to isolate, culture, and assess islet function. The current study compares bovine serum albumin (BSA) types and lipid preparation methods in clonal 832/13 cells and human islets. Changing the percentage and culture conditions when using FFA-free BSA can negatively affect β-cell function compared to regular BSA. Preparing palmitate with FFA-free BSA can rescue insulin secretion compared to treating cells alone with FFA-free BSA. Different methods of preparing palmitate can have unique effects on insulin secretion. Overall, interpreting the effects of lipids on β-cell function is complicated by a number of variables that need to be controlled for in islet experiments.

Islet dimension and its impact on transplant outcome: A systematic review

BACKGROUND

Not all islet transplants desirably achieve insulin independence. This can be attributed to the microarchitecture and function of the islets influenced by their dimensions. Large islets enhance insulin secretion through paracrine effects but are more susceptible to hypoxic injury post-transplant, while small islets offer better viability and insulin independence. In vivo studies suggest large islets are essential for maintaining euglycemia, though smaller islets are typically preferred in transplantation for better outcomes.

AIM

To document the impact of islet dimension on clinical and preclinical transplant outcomes to optimize procedures.

METHODS

PubMed, Scopus and EMBASE platforms were searched for relevant literature up to 9 April 2024. Articles reported on either glucose-stimulated insulin-secreting (GSIS) capacity, islet viability and engraftment, or insulin independence based on the islet dimension were included. The risk of bias was measured using the Appraisal Tool for Cross-Sectional Studies. Extracted data was analyzed via a narrative synthesis.

RESULTS

Nineteen studies were included in the review. A total of sixteen studies reported the GSIS, of which nine documented the increased insulin secretion in the small islet, where the majority reported insulin secretion per islet equivalent (IEQ). Seven studies documented increased GSIS in large-sized islets that measure insulin secretion per cell or islet. All the articles that compared small and large islets reported poor viability and engraftment of large islets.

CONCLUSION

Small islets with a diameter < 125 µm have desired transplantation outcomes due to their better survival following isolation. Large-sized islets receive blood supply directly from arterioles in vivo to meet their higher metabolic demands. The large islet undergoes central necrosis soon after the isolation (devascularization); failing to maintain the viability and glucose stimuli leads to a decline in GSIS and the overall function of the islet. Improved preservation of large islets after islet isolation, enhances the islet yield (IEQ), thereby reducing the likelihood of failed islet isolation and potentially improves transplant outcome.

Hydrogel injection molded complex macroencapsulation device geometry improves long-term cell therapy viability and function in the rat omentum transplant site

Insulin-secreting allogeneic cell therapies are a promising treatment for type 1 diabetes, with the potential to eliminate hypoglycemia and long-term complications of the disease. However, chronic systemic immunosuppression is necessary to prevent graft rejection, and the acute risks associated with immunosuppression limit the number of patients who can be treated with allogeneic cell therapies. Islet macroencapsulation in a hydrogel biomaterial is one proposed method to reduce or eliminate immune suppression; however, macroencapsulation devices suffer from poor oxygen transport and limited efficacy as they scale to large animal model preclinical studies and clinical trials. Hydrogel geometric device designs that optimize nutrient transport combined with methods to promote localized vasculogenesis may improve in vivo macroencapsulated cell viability and function. Here, we demonstrate with finite element modeling that a high surface area-to-volume ratio spiral geometry can increase macroencapsulated islet viability and function relative to a traditional cylindrical design, and we validate these observations in vitro under normoxic and physiological oxygen conditions. Finally, we evaluate macroencapsulated syngeneic islet survival and function in vivo in a diabetic rat omentum transplant model, and demonstrate that high surface area-to-volume hydrogel device designs improved macroencapsulated syngeneic islet function relative to traditional device designs.

Molecular correlates of glycine receptor activity in human β cells

OBJECTIVES

Glycine acts in an autocrine positive feedback loop in human β cells through its ionotropic receptors (GlyRs). In type 2 diabetes (T2D), islet GlyR activity is impaired by unknown mechanisms. We sought to investigate if the GlyR dysfunction in T2D is replicated by hyperglycemia per se, and to further characterize its action in β cells and islets.

METHODS

GlyR-mediated currents were measured using whole-cell patch-clamp in human β cells from donors with or without T2D, or after high glucose (15 mM) culture. We also correlated glycine-induced current amplitude with transcript expression levels through patch-seq. The expression of the GlyR α1, α3, and β subunit mRNA splice variants was compared between islets from donors with and without T2D, and after high glucose culture. Insulin secretion from human islets was measured in the presence or absence of the GlyR antagonist strychnine.

RESULTS

Although gene expression of GlyRs was decreased in T2D islets, and β cell GlyR-mediated currents were smaller, we found no evidence for a shift in GlyR subunit splicing. Glycine-induced currents are also reduced after 48 h culture of islets from donors without diabetes in high glucose, where we also find the reduction of the α1 subunit expression, but an increase in the α3 subunit. We discovered that glycine-evoked currents are highly heterogeneous amongst β cells, inversely correlate with donor HbA1c, and are significantly correlated to the expression of 92 different transcripts and gene regulatory networks (GRNs) that include CREB3(+), RREB1(+) and ZNF697(+). Finally, glucose-stimulated insulin secretion is decreased in the presence of the GlyR antagonist strychnine.

CONCLUSIONS

We demonstrate that glucose can modulate GlyR expression, and that the current decrease in T2D is likely due to the receptor gene expression downregulation, and not a change in transcript splicing. Moreover, we define a previously unknown set of genes and regulons that are correlated to GlyR-mediated currents and could be involved in GlyR downregulation in T2D. Among those we validate the negative impact of EIF4EBP1 expression on GlyR activity.

Integration of Multi-Omics Data and Machine Learning to Identify Antioxidant Biomarkers in Type 1 Diabetes

The identification of biomarkers for early diagnosis and monitoring the progression of Type 1 Diabetes (T1DM) is essential for improving disease management. This study integrates multi-omics data with machine learning to identify antioxidant stress proteins in serum as potential biomarkers. Serum samples from mice treated with varying doses of streptozotocin (STZ) and human transcriptomic data from the gene expression omnibus (GEO) database were analyzed using weighted gene co-expression network analysis (WGCNA). Proteomic analysis of 25 T1DM and 25 healthy controls using LC-MS/MS revealed 33 differentially expressed proteins enriched in oxidative stress pathways. Machine learning algorithms, including Random Forest and SVM-RFE, identified five key proteins: GPX3, GSTP1, PRDX6, SOD1, and MSRB2. GPX3 demonstrated the highest diagnostic value, with a significant correlation to clinical parameters such as HbA1c and fasting plasma glucose. Functional validation showed GPX3 overexpression protected pancreatic β-cells from H2O2-induced oxidative damage and alleviated symptoms and pathological changes in T1DM mice. These results suggest that GPX3 is a promising biomarker for diagnosing and tracking T1DM progression, offering new insights into oxidative stress management in T1DM.

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.

Effects of neutralization and functionalization on chitosan/gelatin/polyvinyl alcohol scaffolds in insulin-producing cell culture

Diabetes is a disease that affects the patient's quality of life. Although there are several studies of therapeutic alternatives, there is still no definitive cure. Polymeric scaffolds represent a promising therapeutic strategy to preserve cell mass through 3D cultures. The aim of this study is to explore an alternative polymeric scaffold based on a mix of chitosan (Chi), gelatin (Ge), and polyvinyl alcohol (PVA) functionalized with VEGF for the culture of insulin-producing cells. The scaffolds were obtained by freeze-thaw cycles and lyophilization, followed by neutralization and, functionalization with vascular endothelial growth factor (VEGF). Physicochemical characteristics, biocompatibility and functionality were evaluated. Scaffolds obtained had interconnected heterogeneous pores. The presence of functional groups confirmed the integration of all the components without significantly losing thermal stability and mass. The functionalized and neutralized scaffolds positively impacted the biocompatibility and insulin secretion. Cell respiration was sustained, and cell morphology demonstrated the formation of cell clusters. It can be concluded that neutralization and functionalization of the scaffolds combined with VEGF are necessary to improve biocompatibility and functionality. Moreover, all these characteristics generated encouraging results on the diffusion of nutrients and cell adhesion, which could be valuable in the translational application for diabetes treatment.

Oxygen dynamics and delivery strategies to enhance beta cell replacement therapy

Beta cell replacement therapy via pancreatic islet transplantation offers a promising treatment for type 1 diabetes as an alternative to insulin injections. However, posttransplantation oxygenation remains a critical challenge; isolated islets from donors lose vascularity and rely on slow oxygen diffusion for survival until revascularization occurs in the host tissue. This often results in significant hypoxia-induced acute graft loss. Overcoming the oxygenation barrier is crucial for advancing islet transplantation. This review is structured in three sections: the first examines oxygen dynamics in islet transplantation, focusing on factors affecting oxygen supply, including vascularity. It highlights oxygen dynamics specific to both transplant sites and islet grafts, with particular attention to extrahepatic sites such as subcutaneous tissue. The second section explores current oxygen delivery strategies, categorized into two main approaches: augmenting oxygen supply and enhancing effective oxygen solubility. The final section addresses key challenges, such as the lack of a clearly defined oxygen threshold for islet survival and the limited precision in measuring oxygen levels within small islet constructs. Recent advancements addressing these challenges are introduced. By deepening the understanding of oxygen dynamics and identifying current obstacles, this review aims to guide the development of innovative strategies for future research and clinical applications. These advancements are anticipated to enhance transplantation outcomes and bring us closer to a cure for type 1 diabetes.

Renalase inhibition defends against acute and chronic β cell stress by regulating cell metabolism

OBJECTIVE

Renalase (Rnls) is annotated as an oxidase enzyme. It has been implicated in Type 1 diabetes (T1D) risk via genome-wide association studies (GWAS). We previously discovered through CRISPR screening and validation experiments that Rnls inhibition prevents or delays T1D in multiple mouse models of diabetes in vivo, and protects pancreatic β cells against autoimmune killing, ER and oxidative stress in vitro. The molecular biochemistry and functions of Rnls are largely uncharted. Here we studied the mechanisms of Rnls inhibition that underlie β cell protection during diabetogenic stress.

METHODS

Akita mice were treated with oral Pargyline (PG) in vivo to bind and inhibit Rnls, and pancreas or islets were harvested for β cell mass and β cell function analyses. Genetic and pharmacological tools were used to inhibit Rnls in β cell lines. RNA sequencing, metabolomics and metabolic function experiments were conducted in vitro in NIT-1 mouse β cell lines and human stem cell-derived β cells.

RESULTS

In vivo, PG improved glycemia and mildly preserved β cell mass and function in females. Genetic strategies to mutate (Rnlsmut) or knockout (Rnls KO) Rnls induced a robust metabolic shift towards glycolysis in both mouse and human β cell lines, in vitro. Stress protection was abolished when glycolysis was blocked with 2-deoxyglucose (2-DG). Pharmacological Rnls inhibition with PG did not strongly mimic these newly identified metabolic mechanisms.

CONCLUSIONS

Our work illustrates a role for Rnls in regulating cell metabolism. We show that inhibiting Rnls protects against chronic stress in vivo, and shields against acute stress in β cell lines in vitro by rewiring cell metabolism towards glycolysis.

RSPO1, a potent inducer of pancreatic β cell neogenesis

Inducing the neogenesis of pancreatic insulin-producing β cells holds great promise for diabetes research. However, non-toxic compounds with such activities remain to be discovered. Herein, we report the identification of RSPO1, a key agonist of the Wnt/β-catenin pathway, as an inducer of β cell replication. Specifically, we provide evidence that RSPO1 promotes a significant increase in β cell neogenesis in vitro, ex vivo, and in vivo. Importantly, RSPO1 administration is sufficient to activate Wnt/β-catenin signaling in β cells and counter chemically induced or autoimmune-mediated diabetes. Similarly, an optimized analog of RSPO1, allowing for weekly administration, also prevents diabetes in vivo. Lastly, the treatment of transplanted human islets with RSPO1 induces a significant 2.78-fold increase in human β cell numbers in only 60 days, these cells being functional. Such activities of RSPO1 to promote β cell neogenesis could therefore represent an unprecedented hope in the continued search for diabetes alternative therapies.

Cohabitation facilitates microbiome shifts that promote isoflavone transformation to ameliorate liver injury

Acetaminophen overuse is a leading cause of acute liver injury (ALI). Although ALI is linked to inter-individual differences in microbiome composition, the mechanisms remain unclear. We demonstrate that horizontal transmission of gut microbiota between male and female mice impacts ALI and identify Rikenellamicrofusus-mediated isoflavone transformation as determinants of ALI severity. R. microfusus increases upon cohabitation with bacterial β-galactosidase enhancing intestinal absorption of isoflavone biochanin-A (Bio-A). R. microfusus mono-colonization reduced ALI severity following acetaminophen overdose. Genetic or chemical-mediated inhibition of β-galactosidase blocked Bio-A release and negated the hepatoprotective effects of R. microfusus. Bio-A directly binds to pyruvate carboxylase (PC) and propionyl-CoA carboxylase subunit alpha (PCCA), augmenting the tricarboxylic acid cycle and promoting protective glutathione synthesis in hepatocytes. Additionally, immunohistochemical analysis revealed reduced hepatic PC and PCCA expression in liver failure (LF) patients. These findings highlight the impacts of microbiome composition on ALI and the ability of microbial isoflavone absorption to mitigate ALI severity.

Microfluidic cell unroofing for the in situ molecular analysis of organelles without membrane permeabilization

Molecular networks of organelle membranes are involved in many cell processes. However, the nature of plasma membrane as a barrier to various analytical tools, including antibodies, makes it challenging to examine intact organelle membranes without affecting their structure and functions via membrane permeabilization. Therefore, in this study, we aimed to develop a microfluidic method to unroof cells and observe the intrinsic membrane molecules in organelles. In our method, single cells were precisely arrayed on the bottom surface of microchannels in a light-guided manner using a photoactivatable cell-anchoring material. At sufficiently short cell intervals, horizontal stresses generated by the laminar flow instantly fractured the upper cell membranes, without significantly affecting some organelles inside the fractured cells. Subsequently, nucleus and other organelles in unroofed cells were observed via confocal fluorescence and scanning electron microscopy. Furthermore, distribution of the mitochondrial membrane protein, translocase of outer mitochondrial membrane 20, on the mitochondrial membrane was successfully observed via immunostaining without permeabilization. Overall, the established cell unroofing method shows great potential to examine the localization, functions, and affinities of proteins on intact organelle membranes.

The role of endothelial cells in pancreatic islet development, transplantation and culture

Endothelial cells (ECs) play pivotal roles in the development and maintenance of tissue homeostasis. During development, vasculature actively involves in organ morphogenesis and functional maturation, through the secretion of angiocrine factors and extracellular matrix components. Islets of Langerhans, essential functional units of glucose homeostasis, are embedded in a dense endothelial capillary network. Islet vasculature not only supplies nutrients and oxygen to endocrine cells but also facilitate the rapid delivery of pancreatic hormones to target tissues, thereby ensuring precise glucose regulation. Diabetes mellitus is a major disease burden and is caused by islet dysfunction or depletion, often accompanied by vessel loss and dysregulation. Therefore, elucidating the regulatory mechanisms of ECs within islets hold profound implications for diabetes therapy. This review provides an overview of recent research advancements on the functional roles of ECs in islet biology, transplantation, and in vitro islet organoid culture.

Automated insulin delivery after beta-cell replacement failure in people living with type 1 diabetes

AIMS

Patients living with highly unstable type 1 diabetes (T1D) are eligible for beta-cell replacement (βCR) therapy (islet or pancreas transplantation). This study aimed to evaluate glycemic control in patients treated with automated insulin delivery (AID) following failed βCR therapy, defined as secondary graft failure or marginal function.

MATERIAL AND METHODS

A national, multicenter, retrospective study was conducted with 23 patients who had βCR failure treated with AID for at least three months. The primary outcome was the proportion of patients achieving recommended glucose targets (time in 70-180mg/dl range [TIR] > 70 %, time below range [TBR] < 4 % and HbA1c < 7 %). Secondary outcomes included TIR, glycemia risk index (GRI), HbA1c, coefficient of variation (CV), body weight, insulin doses, severe hypoglycemia and AID discontinuation.

RESULTS

The proportion of patients achieving recommended glucose targets under AID increased from 5.0 % to 57.1 % after 12 months. TIR increased from 54.2 ± 18.0 % to 75.5 ± 9.6 % after 12-month AID, while GRI decreased from 45.8 ± 22.2 % to 25.6 ± 10.3 %. HbA1c levels decreased from 7.5 ± 0.9 % to 7.0 ± 1.1 % after 12-month AID. CV, body weight and insulin doses did not change. All patients were free from severe hypoglycemia under AID, including those who had experienced severe hypoglycemia after βCR failure. No patient discontinued the AID.

CONCLUSIONS

This study highlights the effectiveness of AID in achieving glucose control targets and preventing severe hypoglycemia in patients with T1D following βCR failure. AID may serve as a valuable therapeutic option to improve glucose control when graft function declines.

Scaffold-free endocrine tissue engineering: role of islet organization and implications in type 1 diabetes

Type 1 diabetes (T1D) is a chronic hyperglycemia disorder emerging from beta-cell (insulin secreting cells of the pancreas) targeted autoimmunity. As the blood glucose levels significantly increase and the insulin secretion is gradually lost, the entire body suffers from the complications. Although various advances in the insulin analogs, blood glucose monitoring and insulin application practices have been achieved in the last few decades, a cure for the disease is not obtained. Alternatively, pancreas/islet transplantation is an attractive therapeutic approach based on the patient prognosis, yet this treatment is also limited mainly by donor shortage, life-long use of immunosuppressive drugs and risk of disease transmission. In research and clinics, such drawbacks are addressed by the endocrine tissue engineering of the pancreas. One arm of this engineering is scaffold-free models which often utilize highly developed cell-cell junctions, soluble factors and 3D arrangement of islets with the cellular heterogeneity to prepare the transplant formulations. In this review, taking T1D as a model autoimmune disease, techniques to produce so-called pseudoislets and their applications are studied in detail with the aim of understanding the role of mimicry and pointing out the promising efforts which can be translated from benchside to bedside to achieve exogenous insulin-free patient treatment. Likewise, these developments in the pseudoislet formation are tools for the research to elucidate underlying mechanisms in pancreas (patho)biology, as platforms to screen drugs and to introduce immunoisolation barrier-based hybrid strategies.

Contributions of Europeans to Xenotransplantation Research: 2. Pig Islet and Cell Xenotransplantation

Pig islet xenotransplantation in nonhuman primates (NHPs) has made considerable progress during the past 30 years, and European scientists in both Europe and the USA have contributed to this progress. At times, there have been, or are, active research programs in Sweden, Germany, Belgium, and the USA. The first clinical experiments of wild-type (i.e., genetically-unmodified) pig islet xenotransplantation were carried out by Groth and his colleagues in Stockholm in 1994, but without significant success. Hering's group in Minneapolis was the first to report prolonged survival of wild-type pig islets in NHPs in 2006, and the first report of insulin-independence for >12 months was by a "European" research team at the University of Pittsburgh in 2009. Recent progress has been slow, in part through a lack of funding, but recent advances in pig organ xenotransplantation suggest that pig islet xenotransplantation is poised for clinical experiments in the near future. In addition, there have been encouraging experimental studies of pig neural cell injections into the brains of monkeys with a pharmacologically-induced Parkinson's disease.

Fibroblast growth factor 23 as a risk factor for incident diabetes

PURPOSE OF REVIEW

Diabetes is a major global health concern, affecting millions and increasing morbidity and mortality. Recent research highlights fibroblast growth factor 23 (FGF23) as a potential contributor to type 2 diabetes and its cardiovascular complications. This review explores the role of FGF23 in metabolic and cardiovascular dysfunction and discusses possible therapeutic interventions.

RECENT FINDINGS

Deregulated FGF23 is linked to insulin resistance, pancreatic β-cell dysfunction, and systemic inflammation. Studies suggest FGF23 influences glucose metabolism via insulin signaling, oxidative stress, and inflammation. Epidemiological data indicate that elevated FGF23 levels are associated with an increased risk of type 2 diabetes and posttransplant diabetes, independent of traditional risk factors. Higher FGF23 levels have also been linked with an increased cardiovascular risk in patients with diabetes, even without chronic kidney disease.

SUMMARY

FGF23 is emerging as a key factor in the cardiovascular-kidney-metabolic syndrome, connecting diabetes and cardiovascular disease. While studies suggest consistent associations, causal mechanisms remain unclear. No therapies specifically target FGF23 to lower diabetes risk, but fibroblast growth factor receptor 4 (FGFR4) inhibitors show promise. Future research should examine the role of FGF23 in individuals with normal kidney function and explore whether modifying its levels could reduce diabetes and cardiovascular risk.

Bioprinting and synthetic biology approaches to engineer functional endocrine pancreatic constructs

Diabetes is a complex disease affecting over 500 million people worldwide. Traditional approaches, such as insulin delivery, are mainstay treatments, but do not cure the disease. Recent advances in biofabrication and synthetic biology offer new hope for the development of tissue constructs recapitulating salient organ functions. Here, we discuss recent progress in bioprinting a functional endocrine pancreas, ranging from cell sources to main advances in biomaterials. We review innovative areas for the development of this field, with a particular focus on the convergence of synthetic biology and cell engineering with bioprinting, which opens new avenues for developing advanced in vitro models and regenerative, transplantable grafts, with the potential to provide independence from exogenous insulin administration.

Clinically compliant enrichment of human pluripotent stem cell-derived islets

Human pluripotent stem cell-derived islet (SC-islet) transplantation is a promising β cell replacement therapy for patients with type 1 diabetes, offering a potential unlimited cell supply. Yet, the heterogeneity of the final cell product containing non-target cell types has relevant implications for SC-islet function, transplant volume, and cell product safety. Here, we present a clinically compliant, full three-dimensional differentiation protocol that includes a purification step of endocrine cell-rich clusters, relying on the principle of isopycnic centrifugation (density gradient separation). Enriched SC-islets displayed signs of functionality in vitro and in vivo. In contrast with antibody-based single-cell sorting approaches, this method does not destroy the islet cytoarchitecture associated with alterations of islet function and cell loss. Furthermore, it is fast, is easily scalable to large cell volumes, and can be applied during cell manufacturing. This method may also contribute to the generation of improved cell-based therapies for regenerative medicine purposes beyond the SC-islet field.

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.

Imeglimin, unlike metformin, does not perturb differentiation of human induced pluripotent stem cells towards pancreatic β-like cells and rather enhances gain in β cell identity gene sets

AIMS/INTRODUCTION

Metformin treatment for hyperglycemia in pregnancy (HIP) beneficially improves maternal glucose metabolism and reduces perinatal complications. However, metformin could impede pancreatic β cell development via impaired mitochondrial function. A new anti-diabetes drug imeglimin, developed based on metformin, improves mitochondrial function. Here we examine the effect of imeglimin on β cell differentiation using human induced pluripotent stem cell (iPSC)-derived pancreatic islet-like spheroid (SC-islet) models.

MATERIALS AND METHODS

Human iPSCs are differentiated into SC-islets by three-dimensional culture with and without imeglimin or metformin. Differentiation efficiencies of SC-islets were analyzed by flow cytometry, immunostaining, quantitative PCR, and insulin secretion assay. RNA sequencing and oxygen consumption rate were obtained for further characterization of SC-islets. SC-islets were cultured with proinflammatory cytokines, in part mimicking the uterus environment in HIP.

RESULTS

Metformin perturbed SC-islet differentiation while imeglimin did not alter it. Furthermore, imeglimin enhanced the gene expressions of β cell lineage markers. Maintenance of mitochondrial function and optimization of TGF-β and Wnt signaling were considered potential mechanisms for augmented β cell maturation by imeglimin. In the presence of proinflammatory cytokines, imeglimin ameliorated β cell differentiation impaired by cytokines and metformin.

CONCLUSIONS

Imeglimin does not perturb differentiation of SC-islet cells and rather enhances gain in β cell identity gene sets in contrast to metformin. This may lead to the improvement of in vitro β cell differentiation protocols.

Long-term blood glucose control via glucose-activated transcriptional regulation of insulin analogue in type 1 diabetes mice

AIM

To achieve glucose-activated transcriptional regulation of insulin analogue in skeletal muscle of T1D mice, thereby controlling blood glucose levels and preventing or mitigating diabetes-related complications.

MATERIALS AND METHODS

We developed the GANIT (Glucose-Activated NFAT-regulated INSA-F Transcription) system, an innovative platform building upon the previously established intramuscular plasmid DNA (pDNA) delivery and expression system. In the GANIT system, skeletal muscle cells are genetically engineered to endogenously produce the insulin analogue INSA-F (Insulin Aspart with Furin cleavage sites). The transcription of INSA-F is precisely controlled by a glucose-responsive promoter containing NFAT (Nuclear Factor of Activated T-cells) regulatory motifs, which can be activated in response to changes in extracellular glucose concentrations. This design enables glucose-dependent regulation of insulin analogue expression, mimicking physiological glucose-responsive insulin secretion.

RESULTS

T1D mice that received two GANIT treatments over a 2-month experimental period demonstrated significant improvements in glucose homeostasis, glucose tolerance and glycated haemoglobin (HbA1c) levels. Additionally, the treatment effectively reduced oxidative stress and alleviated cardiac and renal fibrosis, while maintaining a favourable biosafety profile.

CONCLUSION

The GANIT system provides significant advantages in terms of efficiency, convenience and cost-effectiveness, making it a promising approach for regulating blood glucose levels and alleviating diabetes-related complications in insulin-deficient diabetes.

Genome-Scale Metabolic Modeling of Human Pancreas with Focus on Type 2 Diabetes

Type 2 diabetes (T2D) is characterized by relative insulin deficiency due to pancreatic beta cell dysfunction and insulin resistance in different tissues. Not only beta cells but also other islet cells (alpha, delta, and pancreatic polypeptide [PP]) are critical for maintaining glucose homeostasis in the body. In this overarching context and given that a deeper understanding of T2D pathophysiology and novel molecular targets is much needed, studies that integrate experimental and computational biology approaches offer veritable prospects for innovation. In this study, we report on single-cell RNA sequencing data integration with a generic Human1 model to generate context-specific genome-scale metabolic models for alpha, beta, delta, and PP cells for nondiabetic and T2D states and, importantly, at single-cell resolution. Moreover, flux balance analysis was performed for the investigation of metabolic activities in nondiabetic and T2D pancreatic cells. By altering glucose and oxygen uptakes to the metabolic networks, we documented the ways in which hypoglycemia, hyperglycemia, and hypoxia led to changes in metabolic activities in various cellular subsystems. Reporter metabolite analysis revealed significant transcriptional changes around several metabolites involved in sphingolipid and keratan sulfate metabolism in alpha cells, fatty acid metabolism in beta cells, and myoinositol phosphate metabolism in delta cells. Taken together, by leveraging genome-scale metabolic modeling, this research bridges the gap between metabolic theory and clinical practice, offering a comprehensive framework to advance our understanding of pancreatic metabolism in T2D, and contributes new knowledge toward the development of targeted precision medicine interventions.

Pharmacotherapy of type 1 diabetes - part 2 Today

INTRODUCTION

In the 100 years since isolation and administration of animal insulin to sustain life in Type 1 diabetes, there has been increasing progress in the administration of exogenous insulin to lower glucose levels.

AREAS COVERED

We reviewed using standard search engines and PubMed present-day techniques of management of type 1 diabetes.

EXPERT OPINION

Long-acting insulin formulations have been developed to maintain basal glucose levels in the normal range, while rapid acting insulins have been synthesized to address the sharp rise in glucose levels after a meal. Insulin pumps administer insulin continuously subcutaneously guided by continuous glucose monitoring systems. These almost closed loop systems achieve near normal glucose levels other than at meal times where the rapid glucose rise and then fall pose a significant challenge due to the extended duration of subcutaneous insulin depots. Implanted insulin pumps with intraperitoneal delivery may eventually permit improved post meal glucose control. Type 1 diabetes has now been redefined as an autoimmune disease which may be diagnosed purely from the presence of anti-beta cell antibodies with no abnormality of glucose levels. The future will see an intensification of efforts to combat the immune process which destroys beta cells.

Allogeneic Islet Transplantation: Chronicle of a Death Foretold?

Innovative solutions have entered the routine management of patients with type 1 diabetes or are making the headlines and this is shaking the world of beta cell replacement therapies. Above all, allogeneic islet transplantation is enthusiastically doomed to extinction by the aficionados of "closed loop" artificial insulin delivery systems or those convinced of the imminent large scale availability of stem-cell derived insulin-producing tissues. This opinion paper will propose that neither will be a universal solution in the very near future and will argue that xenogeneic islet transplantation may be a serious outsider in the race for new therapies. In the meantime, the odds are in favor of allogeneic islet (and pancreas) transplantation remaining first line options in the treatment of complicated type 1 diabetes. There is no question that "closed loop" systems have already greatly improved the management of type 1 diabetes, but, while "unlimited" sources of insulin-producing cells are jockeying for approval as standard-of-care, these improvements are more likely to drive a shift of indications -from islet transplant alone to simultaneous islet-kidney transplantation- than to herald the demise of islet transplantation.

A novel intravascular bioartificial pancreas device shows safety and islet functionality over 30 days in nondiabetic swine

In this study using a discordant, xenogeneic, transplant model we demonstrate the functionality and safety of the first stent-based bioartificial pancreas (BAP) device implanted endovascularly into an artery, harnessing the high oxygen content in blood to support islet viability. The device is a self-expanding nitinol stent that is coated with a bilayer of polytetrafluoroethylene that forms channels to hold islets embedded in a hydrogel. We completed a 1-month study in the nondiabetic swine model (N = 3) to test the safety of the device and to assess islet functionality after device recovery. The luminal diameter of the devices from 3 animals on day 0 and day 30 was 10.01 ± 0.408 mm and 10.05 ± 0.25 mm, respectively. The stimulation index of the control and endovascular BAP devices explanted at day 30 were 3.35 ± 0.97 and 4.83 ±1.20, respectively, and the islets stained positively for insulin and glucagon after 30 days in vivo. This pilot study shows that BAP implantation into a peripheral artery is safe and supports islet functionality over 30 days, providing the groundwork for future work assessing the in vivo function of the device in diabetic swine.

Transition from preclinical to clinical application of CTLA4-Ig co-stimulation blockage in beta-cell replacement therapy

Beta-cell replacement therapies, including islet and pancreas transplantation, offer promising results in term of glycemic control for patients with type 1 diabetes experiencing high glycemic variability and severe hypoglycemia. However, long-term insulin independence remains challenging due to progressive graft function decline. Immunosuppressive regimens, especially calcineurin inhibitors such as tacrolimus, are known to be diabetogenic, contributing to the paradox of impaired beta-cell function in a diabetes treatment setting. Recent studies have focused on CTLA4-Ig (e.g., belatacept) as a potential alternative to calcineurin inhibitors, showing promising results in preclinical and clinical models. This review summarizes key advancements and remaining challenges in CTLA4 applications for beta-cell replacement. First, genetic engineering approaches aiming for CTLA4 expression in islets demonstrated initial success in delaying rejection but remain hindered by immune escape and limited integration efficacy. Coating techniques and exogenous CTLA4-Ig administration offer simpler, albeit transient, immunosuppressive effects, which, combined with encapsulation technologies, can improve graft survival. In non-human primate models, islet transplantation with immunosuppressant regimen using CTLA4-Ig combined with agents such as sirolimus or anti-CD154 has shown extended insulin independence, though full immune tolerance remains elusive. A limited number of human studies using belatacept for beta-cell replacement indicate reduced HbA1c levels and avoidance of severe hypoglycemia, yet consistent absence of rejection remains unachieved. Future research on BCR with CTLA4-Ig should explore graft survival in human islets transplantation and refine immunosuppressive protocols to leverage CTLA4-Ig potential in improving long-term graft function, thus enhancing the sustainability of CTLA4-Ig in clinical beta-cell replacement approach.

The concept of immunothrombosis in pancreas transplantation

Early failure of a pancreatic allograft due to complete thrombosis has an incidence of approximately 10% and is the main cause of comorbidity in pancreas transplantation. Although several risk factors have been identified, the exact mechanisms leading to this serious complication are still unclear. In this review, we define the roles of the individual components involved during sterile immunothrombosis-namely endothelial cells, platelets, and innate immune cells. Further, we review the published evidence linking the main risk factors for pancreatic thrombosis to cellular activation and vascular modifications. We also explore the unique features of the pancreas itself: the vessel endothelium, specific vascularization, and relationship to other organs-notably the spleen and adipose tissue. Finally, we summarize the therapeutic possibilities for the prevention of pancreatic thrombosis depending on the different mechanisms such as anticoagulation, anti-inflammatory molecules, endothelium protectors, antagonism of damage-associated molecular patterns, and use of machine perfusion.

miR-214-3p attenuates ferroptosis-induced cellular damage in a mouse model of diabetic retinopathy through the p53/SLC7A11/GPX4 axis

Ferroptosis has been implicated in the development of diabetic retinopathy (DR). This study aimed to identify novel ferroptosis-related regulators involved in the pathophysiology of DR using an in vivo streptozotocin (STZ)-induced diabetic model in C57BL/6J mice and cultured primary human retinal vascular endothelial cells (HRECs). Transmission electron microscopy revealed mitochondrial morphological changes consistent with ferroptosis in vascular endothelial cells from STZ-treated mice. Western blot analysis showed increased levels of ferroptosis markers (4-HNE, p53, phosphorylated p53) along with decreased levels of glutathione (GSH), SLC7A11, and GPX4 in diabetic mice. In vitro experiments demonstrated that ferroptosis inhibitors, including pifithrin-α (a p53 inhibitor) and ferrostatin-1 (Fer-1), mitigated cellular damage and Fe2+ accumulation in high-glucose-treated HRECs. These inhibitors also improved mitochondrial membrane potential and restored GSH levels. Bioinformatics analysis and dual-luciferase assays identified a p53 binding site within the miR-214-3p sequence. Overexpression of miR-214-3p in high-glucose-treated HRECs resulted in downregulation of p53 and upregulation of SLC7A11 and GPX4, thereby alleviating ferroptosis-induced injury. This study demonstrates that ferroptosis contributes to retinal damage at tissue, cellular, and molecular levels in DR. Specifically, p53, regulated by miR-214-3p, promotes ferroptosis through the SLC7A11/GPX4 pathway under high-glucose conditions. These findings suggest that the miR-214-3p/p53/SLC7A11/GPX4 axis could serve as a potential therapeutic target for managing ferroptosis and retinal damage in diabetic retinopathy.

Redox signaling in the pancreas in health and disease

This review addresses oxidative stress and redox signaling in the pancreas under healthy physiological conditions as well as in acute pancreatitis, chronic pancreatitis, pancreatic cancer, and diabetes. Physiological redox homeodynamics is maintained mainly by NRF2/KEAP1, NF-κB, protein tyrosine phosphatases, peroxisome proliferator-activated receptor-γ coactivator 1α (PGC1α), and normal autophagy. Depletion of reduced glutathione (GSH) in the pancreas is a hallmark of acute pancreatitis and is initially accompanied by disulfide stress, which is characterized by protein cysteinylation without increased glutathione oxidation. A cross talk between oxidative stress, MAPKs, and NF-κB amplifies the inflammatory cascade, with PP2A and PGC1α as key redox regulatory nodes. In acute pancreatitis, nitration of cystathionine-β synthase causes blockade of the transsulfuration pathway leading to increased homocysteine levels, whereas p53 triggers necroptosis in the pancreas through downregulation of sulfiredoxin, PGC1α, and peroxiredoxin 3. Chronic pancreatitis exhibits oxidative distress mediated by NADPH oxidase 1 and/or CYP2E1, which promotes cell death, fibrosis, and inflammation. Oxidative stress cooperates with mutant KRAS to initiate and promote pancreatic adenocarcinoma. Mutant KRAS increases mitochondrial reactive oxygen species (ROS), which trigger acinar-to-ductal metaplasia and progression to pancreatic intraepithelial neoplasia (PanIN). ROS are maintained at a sufficient level to promote cell proliferation, while avoiding cell death or senescence through formation of NADPH and GSH and activation of NRF2, HIF-1/2α, and CREB. Redox signaling also plays a fundamental role in differentiation, proliferation, and insulin secretion of β-cells. However, ROS overproduction promotes β-cell dysfunction and apoptosis in type 1 and type 2 diabetes.

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.

Active targeting of type 1 diabetes therapies to pancreatic beta cells using nanocarriers

Type 1 diabetes is an autoimmune disease characterised by the destruction of pancreatic beta cells, resulting in lifelong insulin dependence. Although exogenous insulin can maintain glycaemic control, this approach does not protect residual or replacement pancreatic beta cells from immune-mediated death. Current therapeutics designed to protect functional beta cell mass or promote beta cell proliferation and regeneration can have off-target effects, resulting in higher dose requirements and adverse side effects. Targeted drug delivery using nanocarriers has demonstrated potential for overcoming these limitations. The critical bottleneck limiting the development of beta cell-targeted therapies is a lack of highly specific beta cell markers. This review provides an overview of the use of nanocarriers for cell-targeted delivery and the current state of the field of beta cell targeting. Technologies such as systematic evolution of ligands by exponential enrichment (SELEX) aptamer selection, phage display screening, and omics datasets from human samples are highlighted as tools to identify novel beta cell-specific targets that can be combined with nanocarriers for targeted delivery of therapeutics. Ultimately, beta cell-targeted therapies using nanocarriers present a unique opportunity to develop tailored treatments for each stage of type 1 diabetes with the goal of providing individuals with treatment options that prevent further progression or reverse the course of the disease.

A perfect islet: reviewing recent protocol developments and proposing strategies for stem cell derived functional pancreatic islets

The search for an effective cell replacement therapy for diabetes has driven the development of "perfect" pancreatic islets from human pluripotent stem cells (hPSCs). These hPSC-derived pancreatic islet-like β cells can overcome the limitations for disease modelling, drug development and transplantation therapies in diabetes. Nevertheless, challenges remain in generating fully functional and mature β cells from hPSCs. This review underscores the significant efforts made by researchers to optimize various differentiation protocols aimed at enhancing the efficiency and quality of hPSC-derived pancreatic islets and proposes methods for their improvement. By emulating the natural developmental processes of pancreatic embryogenesis, specific growth factors, signaling molecules and culture conditions are employed to guide hPSCs towards the formation of mature β cells capable of secreting insulin in response to glucose. However, the efficiency of these protocols varies greatly among different human embryonic stem cell (hESC) and induced pluripotent stem cell (hiPSC) lines. This variability poses a particular challenge for generating patient-specific β cells. Despite recent advancements, the ultimate goal remains to develop a highly efficient directed differentiation protocol that is applicable across all genetic backgrounds of hPSCs. Although progress has been made, further research is required to optimize the protocols and characterization methods that could ensure the safety and efficacy of hPSC-derived pancreatic islets before they can be utilized in clinical settings.

Mettl3 deficiency leads to impaired insulin secretion via regulating Ire1a of mature β-cells in mice

The modification of N6-methyladenosine (m6A) influences the translation and stability of transcripts, allowing for the coordination of gene regulation during cell state maintenance and transition. Deregulation of components in the m6A regulatory network is associated with glucose homeostasis and development of diabetes. In this study, we investigated the functional role of Mettl3, which is the key component of the m6A methyltransferase complex, in regulating β-cell identity and function in two pancreatic β-cell-specific Mettl3 knockout mouse models. The glucose metabolic phenotype, β-cell proliferation, islet architecture and insulin secretion were analyzed in vivo. We next analyzed the expression levels of genes associated with endoplasmic reticulum (ER) stress in the Mettl3 ablated islets. MeRIP-qPCR was applied to detect the m6A modification enrichment of Ire1α mRNA. Adenovirus-mediated Mettl3 infection was performed on islets to explore the effect of Mettl3 overexpression on ER stress and insulin secretion. Our results showed that Mettl3 deficiency led to loss of β-cell identity and impaired insulin secretion in mice. Depletion of Mettl3 verified the m6A modification in Ire1α and consequently induced ER stress in islet cells. Mettl3 overexpression in islets could alleviate ER stress and improve the insulin secretion capacity. Our findings demonstrated that Mettl3 was an important regulator of ER stress and insulin secretion in mouse pancreatic β-cells.

Pancreatic 3D Organoids and Microfluidic Systems-Applicability and Utilization in Surgery: A Literature Review

Background: Pancreatic organoids are a rapidly advancing field of research with new discoveries being made every day. A literature review was performed to answer the question of how relevant 3D pancreatic organoids are for surgery. Materials and Methods: We started our investigation by identifying articles in PubMed within the last 5 years using the keywords (("pancreatic organoid", OR "organ-on-a-chip", OR "pancreatic chip" OR "3D culture methods") AND pancreatic surgery). Only English articles were included in this literature review. This literature review was performed in a non-systematic way; articles were chosen without a predetermined protocol of inclusion and were based on the aim of the review. Results and Conclusions: There are many promising innovations in the field of 3D cultures. Drug sensitivity testing in particular holds great potential for surgical application. For locally advanced PDAC, EUS-FNB obtained cancer tissue can be cultured as organoids, and after 4 weeks, neoadjuvant treatment could be adjusted for each patient individually. Utilizing this approach could increase the number of R0 resections and possibly cure the disease. Furthermore, microfluidic devices, as a platform for pancreatic islet pre-transplant evaluation or cultivation of beta cells derived from HiPSC in vitro, promise broad application of islet transplantation to T1DM patients in the near future.

Glucose Control in Type 1 Diabetes after Pancreas Transplantation: Does Automated Delivery Offer Comparable Results?

Objectives: Pancreas transplantation provides long-term near-normal glycemic control for recipients with type 1 diabetes, but it is unknown how this control compares with an automated insulin delivery (AID) system. Methods: In this prospective study, we compared parameters from 31 consecutive pancreas-kidney transplantation recipients versus from 377 people using an AID-either MiniMed™ 780G (n = 200) or Tandem t:slim X2™ Control-IQ™ (n = 177). Results: Compared with the MiniMed and Tandem AID groups, transplant recipients at 1 month (mean ± standard deviation [SD]: 36 ± 12 days) after pancreas transplantation exhibited significantly lower glycated hemoglobin (38 mmol/mol [36, 40] vs. 55 [53, 56.5] and 56 [54.7, 57.2], respectively), lower mean glycemia (6.4 mmol/L [6, 6.8] vs. 8.5 [8.3, 8.7] and 8.2 [8.0, 8.4], respectively), and spent more time in range (90% [86, 93] vs. 72% [70, 74] and 75% [73, 77], respectively). Time in hypoglycemia did not differ significantly between the groups. Conclusions: Overall, compared with AID treatment, pancreas transplantation led to significantly better diabetes control parameters, with the exception of time below range. Clinical trials registration number is Eudra CT No. 2019-002240-24.

From Edmonton to Lantidra and beyond: immunoengineering islet transplantation to cure type 1 diabetes

Type 1 diabetes (T1D) is characterized by the autoimmune destruction of insulin-producing β cells within pancreatic islets, the specialized endocrine cell clusters of the pancreas. Islet transplantation has emerged as a β cell replacement therapy, involving the infusion of cadaveric islets into a patient's liver through the portal vein. This procedure offers individuals with T1D the potential to restore glucose control, reducing or even eliminating the need for exogenous insulin therapy. However, it does not address the underlying autoimmune condition responsible for T1D. The need for systemic immunosuppression remains the primary barrier to making islet transplantation a more widespread therapy for patients with T1D. Here, we review recent progress in addressing the key limitations of islet transplantation as a viable treatment for T1D. Concerns over systemic immunosuppression arise from its potential to cause severe side effects, including opportunistic infections, malignancies, and toxicity to transplanted islets. Recognizing the risks, the Edmonton protocol (2000) marked a shift away from glucocorticoids to prevent β cell damage specifically. This transition led to the development of combination immunosuppressive therapies and the emergence of less toxic immunosuppressive and anti-inflammatory drugs. More recent advances in islet transplantation derive from islet encapsulation devices, biomaterial platforms releasing immunomodulatory compounds or surface-modified with immune regulating ligands, islet engineering and co-transplantation with accessory cells. While most of the highlighted studies in this review remain at the preclinical stage using mouse and non-human primate models, they hold significant potential for clinical translation if a transdisciplinary research approach is prioritized.

Anti-TNFα as an Adjunctive Therapy in Pancreas and Kidney Transplantation

The rate of early pancreas allograft failure remains high due to thrombosis but also to severity of rejection episodes. We investigated if adjunct anti-TNFα therapy was safe and could improve outcomes after pancreas transplantation. We investigated all pancreas transplants performed in our institution between 2010 and 2022. Etanercept, an anti TNFα therapy, was added to our standard immunosuppressive regimen since 2017 after approval from our institutional human ethics committee. Pancreas survival, rejection episodes, as well as infectious complications were analyzed. A total of 236 pancreas transplants were included, among whom 87 received Etanercept for induction. In multivariable analysis, after adjustment on confounding variables, pancreas survival did not differ between groups (HR = 0.92, CI 95% = 0.48; 1.73, p = 0.79). However, patients receiving Etanercept presented a significantly lower occurrence of pancreas rejection in multivariate analysis (HR = 0.36, CI 95% = 0.14; 0.95, p = 0.04). Patients receiving Etanercept did not experienced a higher risk of bacterial, fungal, CMV nor BK virus infections compared to the non-treated group. The use of anti-TNFα after pancreas transplantation was safe and did not increase infectious complications. Despite a similar rate of thrombosis, anti-TNFα significantly reduced pancreatic rejection, thus supporting its use among pancreas transplant recipients.

Reviving hope: unlocking pancreatic islet immortality by optimizing a trehalose-based cryopreservation media and cell-penetrating peptide

BACKGROUND

Diabetes mellitus remains a pervasive global health concern, urging a deeper exploration of islet transplantation as a potential enduring solution. The efficacy of this therapeutic approach pivots on the precision of cryopreservation techniques, ensuring both the viability and accessibility of pancreatic islets. This study delves into the merits of cryopreserving these islets using the disaccharide trehalose, accompanied by an inventive strategy involving poly L proline (PLP) as a cell-penetrating peptide to overcome the cryoprotectant limitations inherent to trehalose.

METHODS

In our experiments with rat islets, we conducted meticulous viability assessments for fresh and frozen samples. We employed a spectrum of methods, including live/dead staining, insulin/glucagon staining, and measurement of reactive oxygen species (ROS) levels. To gauge functional integrity, we executed glucose-stimulated insulin secretion tests. Subsequently, we transplanted thawed islets into diabetic mice to scrutinize their performance in clinically relevant conditions.

RESULTS

Our study yielded compelling results, affirming the successful cryopreservation of pancreatic islets using trehalose and PLP. Viability, as corroborated through live/dead and insulin/glucagon staining, underscored the sustained preservation of frozen islets. Moreover, these preserved islets exhibited functional integrity by releasing insulin responsively to glucose stimulation. Significantly, upon transplantation into diabetic mice, the thawed islets proficiently restored euglycemia, evidenced by a substantial reduction in fasting blood glucose and an enhanced glucose tolerance.

CONCLUSION

Our findings accentuate the potential of trehalose and PLP as sophisticated cryoprotectants for preserving pancreatic islets. Beyond highlighting viability and functionality, the preserved islets demonstrated a remarkable capacity to restore euglycemia post-transplantation. This research holds promise in addressing the inherent limitations of islet transplantation, particularly in the realm of Type 1 diabetes treatment.

Best practices in islet transplantation in mice

Islet transplantation in mice serves as a crucial preclinical model for understanding alloimmune and autoimmune mechanisms, optimizing immunosuppressive strategies, and developing novel therapies for diabetes. This review provides a comprehensive overview of best practices in murine islet transplantation, including diabetes induction models, technical aspects of islet transplantation, and criteria for transplant graft and rejection. We discuss the immunological challenges posed by major histocompatibility complex disparities, the impact of various transplantation sites, and the limitations of murine models in translating findings to clinical settings. Special emphasis is placed on emerging strategies such as stem cell-derived insulin-producing cells, immune tolerance induction, and alternative transplantation sites. Although mouse models have significantly advanced our understanding of diabetes and β-cell replacement, their inherent differences from human physiology necessitate careful interpretation of findings. The review also highlights novel imaging modalities, immunosuppressive protocols, and biomarkers for graft monitoring, underscoring the need for further refinement of these models to bridge the gap between experimental research and clinical application. By standardizing methodologies and addressing translational limitations, murine islet transplantation studies remain a key model in transplantation and can continue to shape the future of β-cell replacement therapies for insulin-dependent diabetes.

Breaking the Feedback Loop of β-Cell Failure: Insight into the Pancreatic β-Cell's ER-Mitochondria Redox Balance

Pancreatic β-cells rely on a delicate balance between the endoplasmic reticulum (ER) and mitochondria to maintain sufficient insulin stores for the regulation of whole animal glucose homeostasis. The ER supports proinsulin maturation through oxidative protein folding, while mitochondria supply the energy and redox buffering that maintain ER proteostasis. In the development of Type 2 diabetes (T2D), the progressive decline of β-cell function is closely linked to disruptions in ER-mitochondrial communication. Mitochondrial dysfunction is a well-established driver of β-cell failure, whereas the downstream consequences for ER redox homeostasis have only recently emerged. This interdependence of ER-mitochondrial functions suggests that an imbalance is both a cause and consequence of metabolic dysfunction. In this review, we discuss the regulatory mechanisms of ER redox control and requirements for mitochondrial function. In addition, we describe how ER redox imbalances may trigger mitochondrial dysfunction in a vicious feed forward cycle that accelerates β-cell dysfunction and T2D onset.

The future of islet transplantation beyond the BLA approval: challenges and opportunities

This opinion paper explores the path forward for islet transplantation as a cell therapy for type 1 diabetes, following the Biologics License Application (BLA) approval. The authors review key challenges and opportunities that lie ahead. After a brief overview of the history of human islet transplantation, the paper examines the FDA's regulatory stance on isolated islet cells and the requirements for obtaining a BLA. The authors discuss the significance of this approval and the critical steps necessary to broaden patient access, such as scaling up production, clinical integration, reimbursement frameworks, post-marketing surveillance, and patient education initiatives. The paper highlights that the approval of LANTIDRA as an allogeneic cell transplant for uncontrolled type 1 diabetes marks the beginning of new chapters in improving islet transplantation. The authors emphasize essential areas for development, including advancements in islet manufacturing, optimization of transplant sites, islet encapsulation, exploration of unlimited cell sources, and gene editing technologies. In conclusion, the future of islet transplantation beyond the BLA approval presents challenges and opportunities. While significant regulatory milestones have been reached, hurdles remain. Innovations in stem cell-derived islets, cell encapsulation, and gene editing show promise in enhancing graft survival, expanding the availability of transplantable cells, and reducing the reliance on immunosuppressive drugs. These advancements could pave the way for more accessible, durable, and personalized diabetes treatments.

Oxidative phosphorylation is a key feature of neonatal monocyte immunometabolism promoting myeloid differentiation after birth

Neonates primarily rely on innate immune defense, yet their inflammatory responses are usually restricted compared to adults. This is controversially interpreted as a sign of immaturity or essential programming, increasing or decreasing the risk of sepsis, respectively. Here, combined transcriptomic, metabolic, and immunological studies in monocytes of healthy individuals reveal an inverse ontogenetic shift in metabolic pathway activities with increasing age. Neonatal monocytes are characterized by enhanced oxidative phosphorylation supporting ongoing myeloid differentiation. This phenotype is gradually replaced during early childhood by increasing glycolytic activity fueling the inflammatory responsiveness. Microbial stimulation shifts neonatal monocytes to an adult-like metabolism, whereas ketogenic diet in adults mimicking neonatal ketosis cannot revive a neonate-like metabolism. Our findings disclose hallmarks of innate immunometabolism during healthy postnatal immune adaptation and suggest that premature activation of glycolysis in neonates might increase their risk of sepsis by impairing myeloid differentiation and promoting hyperinflammation.

The Kv2.2 channel mediates the inhibition of prostaglandin E2 on glucose-stimulated insulin secretion in pancreatic β-cells

Prostaglandin E2 (PGE2) is an endogenous inhibitor of glucose-stimulated insulin secretion (GSIS) and plays an important role in pancreatic β-cell dysfunction in type 2 diabetes mellitus (T2DM). This study aimed to explore the underlying mechanism by which PGE2 inhibits GSIS. Our results showed that PGE2 inhibited Kv2.2 channels via increasing PKA activity in HEK293T cells overexpressed with Kv2.2 channels. Point mutation analysis demonstrated that S448 residue was responsible for the PKA-dependent modulation of Kv2.2. Furthermore, the inhibitory effect of PGE2 on Kv2.2 was blocked by EP2/4 receptor antagonists, while mimicked by EP2/4 receptor agonists. The immune fluorescence results showed that EP1-4 receptors are expressed in both mouse and human β-cells. In INS-1(832/13) β-cells, PGE2 inhibited voltage-gated potassium currents and electrical activity through EP2/4 receptors and Kv2.2 channels. Knockdown of Kcnb2 reduced the action potential firing frequency and alleviated the inhibition of PGE2 on GSIS in INS-1(832/13) β-cells. PGE2 impaired glucose tolerance in wild-type mice but did not alter glucose tolerance in Kcnb2 knockout mice. Knockout of Kcnb2 reduced electrical activity, GSIS and abrogated the inhibition of PGE2 on GSIS in mouse islets. In conclusion, we have demonstrated that PGE2 inhibits GSIS in pancreatic β-cells through the EP2/4-Kv2.2 signaling pathway. The findings highlight the significant role of Kv2.2 channels in the regulation of β-cell repetitive firing and insulin secretion, and contribute to the understanding of the molecular basis of β-cell dysfunction in diabetes.

Abdominal normothermic regional perfusion after donation after circulatory death improves pancreatic islet isolation yield

Abdominal normothermic regional perfusion (aNRP) is an in situ normothermic oxygenated donor perfusion technique before procurement during controlled donation after circulatory death (cDCD) procedures and allows for organ quality evaluation. There are few data on the effect of aNRP on pancreatic islet isolation and subsequent transplantation outcomes. We aim to evaluate the impact of aNRP on cDCD pancreatic islet isolation and transplantation. A retrospective analysis was performed on pancreatic islet isolation outcomes from aNRP, cDCD, and donation after brain death pancreases. Isolations were compared to previous donor age (60-75 years) matched isolations. Islet function was assessed by a dynamic glucose-stimulated insulin secretion. Donor baseline characteristics did not differ among groups. Isolations from aNRP pancreases (471 739 islet equivalents [IEQ] [655 435-244 851]) yielded more islets compared to cDCD (218 750 IEQ [375 951-112 364], P < .01) and to donation after brain death (206 522 IEQ [385 544-142 446], P = .03) pancreases. Dynamic glucose-stimulated insulin secretion tests in 7 aNRP islet preparations showed a mean stimulation index of 4.91, indicating good functionality. Bilirubin and alanine aminotransferase during aNRP correlated with islet yield (r2 = 0.685, P = .002; r2 = 0.491, P = .016, respectively). Islet isolation after aNRP in cDCD donors results in a high islet yield with viable functional islets. aNRP could increase the utilization of the pancreases for islet transplantation.