Elucidating T cell dynamics and molecular mechanisms in syngeneic and allogeneic islet transplantation through single-cell RNA sequencing.

Islet transplantation is a promising therapy for diabetes treatment. However, the molecular underpinnings governing the immune response, particularly T-cell dynamics in syngeneic and allogeneic transplant settings, remain poorly understood. Understanding these T cell dynamics is crucial for enhancing graft acceptance and managing diabetes treatment more effectively. This study aimed to elucidate the molecular mechanisms, gene expression differences, biological pathway alterations, and intercellular communication patterns among T-cell subpopulations after syngeneic and allogeneic islet transplantation. Using single-cell RNA sequencing, we analyzed cellular heterogeneity and gene expression profiles using the Seurat package for quality control and dimensionality reduction through t-SNE. Differentially expressed genes (DEGs) were analyzed among different T cell subtypes. GSEA was conducted utilizing the HALLMARK gene sets from MSigDB, while CellChat was used to infer and visualize cell-cell communication networks. Our findings revealed genetic variations within T-cell subpopulations between syngeneic and allogeneic islet transplants. We identified significant DEGs across these conditions, highlighting molecular discrepancies that may underpin rejection or other immune responses. GSEA indicated activation of the interferon-alpha response in memory T cells and suppression in CD4+ helper and γδ T cells, whereas TNFα signaling via NFκB was particularly active in regulatory T cells, γδ T cells, proliferating T cells, and activated CD8+ T cells. CellChat analysis revealed complex communication patterns within T-cell subsets, notably between proliferating T cells and activated CD8+ T cells. In conclusion, our study provides a comprehensive molecular landscape of T-cell diversity in islet transplantation. The insights into specific gene upregulation in xenotransplants suggest potential targets for improving graft tolerance. The differential pathway activation across T-cell subsets underscores their distinct roles in immune responses posttransplantation.

Supragel-mediated efficient generation of pancreatic progenitor clusters and functional glucose-responsive islet-like clusters.

Although several synthetic hydrogels with defined stiffness have been developed to facilitate the proliferation and maintenance of human pluripotent stem cells (hPSCs), the influence of biochemical cues in lineage-specific differentiation and functional cluster formation has been rarely reported. Here, we present the application of Supragel, a supramolecular hydrogel formed by synthesized biotinylated peptides, for islet-like cluster differentiation. We observed that Supragel, with a peptide concentration of 5 mg/mL promoted spontaneous hPSCs formation into uniform clusters, which is mainly attributable to a supporting stiffness of ∼1.5 kPa as provided by the Supragel matrix. Supragel was also found to interact with the hPSCs and facilitate endodermal and subsequent insulin-secreting cell differentiation, partially through its components: the sequences of RGD and YIGSR that interacts with cell membrane molecules of integrin receptor. Compared to Matrigel and suspension culturing conditions, more efficient differentiation of the hPSCs was also observed at the stages 3 and 4, as well as the final stage toward generation of insulin-secreting cells. This could be explained by 1) suitable average size of the hPSCs clusters cultured on Supragel; 2) appropriate level of cell adhesive sites provided by Supragel during differentiation. It is worth noting that the Supragel culture system was more tolerance in terms of the initial seeding densities and less demanding, since a standard static cell culture condition was sufficient for the entire differentiation process. Our observations demonstrate a positive role of Supragel for hPSCs differentiation into islet-like cells, with additional potential in facilitating germ layer differentiation.

Type 1 diabetes mellitus following COVID-19 vaccination: a report of two cases and review of literature.

Severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2) infection, which led to the coronavirus 2019 (COVID-19) pandemic, has promoted the development of novel therapeutic agents and vaccines to combat the global spread of the virus. While the COVID-19 vaccines approved thus far have proven to be effective in clinical settings, there have been reports of autoimmune diseases occurring following vaccination, including autoimmune/inflammatory syndrome induced by adjuvant syndrome. We herein report two cases of type 1 diabetes mellitus that occurred following COVID-19 vaccination and provide a literature review. Both cases received multiple vaccinations as recommended to ensure optimal antibody titers. Moreover, the HLA associated with susceptibility to type 1 diabetes was prototypic in both cases. This indirect evidence suggests that the COVID-19 vaccines may be implicated in the pathogenesis of type 1 diabetes. Further case reports to establish a clearer understanding of a potential association are warranted. Supplementary Information: The online version contains supplementary material available at 10.1007/s13340-024-00695-9.

Human research islet cell culture outcomes at the Alberta Diabetes Institute IsletCore.

Human islets from deceased organ donors have made important contributions to our understanding of pancreatic endocrine function and continue to be an important resource for research studies aimed at understanding, treating, and preventing diabetes. Understanding the impacts of isolation and culture upon the yield of human islets for research is important for planning research studies and islet distribution to distant laboratories. Here, we examine islet isolation and cell culture outcomes at the Alberta Diabetes Institute (ADI) IsletCore (n = 197). Research-focused isolations typically have a lower yield of islet equivalents (IEQ), with a median of 252,876 IEQ, but a higher purity (median 85%) than clinically focused isolations before culture. The median recovery of IEQs after culture was 75%, suggesting some loss. This was associated with a shift toward smaller islet particles, indicating possible islet fragmentation, and occurred within 24 h with no further loss after longer periods of culture (up to 136 h). No overall change in stimulation index as a measure of islet function was seen with culture time. These findings were replicated in a representative cohort of clinical islet preparations from the Clinical Islet Transplant Program at the University of Alberta. Thus, loss of islets occurs within 24 h of isolation, and there is no further impact of extended culture prior to islet distribution for research.

12-Lipoxygenase inhibition suppresses islet immune and inflammatory responses and delays autoimmune diabetes in human gene replacement mice.

Type 1 diabetes (T1D) is characterized by the autoimmune destruction of insulin-producing ß cells and involves an interplay between ß cells and cells of the innate and adaptive immune systems. We investigated the therapeutic potential of targeting 12-lipoxygenase (12-LOX), an enzyme implicated in inflammatory pathways in ß cells and macrophages, using a mouse model in which the endogenous mouse Alox15 gene is replaced by the human ALOX12 gene. Our findings demonstrate that VLX-1005, a potent 12-LOX inhibitor, effectively delays the onset of autoimmune diabetes in human gene replacement non-obese diabetic (NOD) mice. By spatial proteomics analysis, VLX-1005 treatment resulted in marked reductions in infiltrating T and B cells and macrophages with accompanying increases in immune checkpoint molecules PD-L1 and PD-1, suggesting a shift towards an immune-suppressive microenvironment. RNA sequencing analysis of isolated islets from inhibitor-treated mice revealed significant alteration of cytokine-responsive pathways. RNA sequencing of polarized proinflammatory macrophages showed that VLX-1005 significantly reduced the interferon response. Our studies demonstrate that the ALOX12 human replacement gene mouse provides a platform for the preclinical evaluation of LOX inhibitors and supports VLX-1005 as an inhibitor of human 12-LOX that engages the enzymatic target and alters the inflammatory phenotypes of islets and macrophages to promote the delay of autoimmune diabetes.

Celiac and superior mesenteric ganglia removal improves glucose tolerance and reduces pancreas islet size.

The sympathetic nervous system is crucial for the regulation of visceral organ function. For instance, the activation of the sympathetic nervous system promotes glycogenolysis in the liver and modulates glucagon and insulin release from the pancreas, thereby raising blood glucose levels. A decrease in sympathetic nerve activity has the opposite effect. Although such acute effects of sympathetic activity changes have been studied, their long-term outcomes have not been previously examined. In this study, we removed the celiac/superior mesenteric ganglia, where sympathetic postganglionic neurons innervating pancreas and liver locate, and examined its effects on glucose homeostasis and islet size several weeks after surgery. Consistent with the reduction in gluconeogenesis, glucose tolerance improved in gangliectomized mice. However, contrary to our expectation that the inhibition of pancreatic function by sympathetic nerves would be relieved with gangliectomy, insulin or C-peptide release did not increase. Examining the size distribution of pancreatic islets, we identified that the gangliectomy led to a size reduction in large islets and a decrease in the proportion of α and ß cells within each islet, as analyzed by immunostaining for insulin and glucagon, respectively. These results indicate that the absence of sympathetic nerve activity reduces the size of the pancreatic islets within a few weeks to reinstate the homeostatic mechanism of blood glucose levels.

Exploring Novel Treatment Modalities for Type 1 Diabetes Mellitus: Potential and Prospects.

Despite the effectiveness of insulin injections in managing hyperglycemia in type 1 diabetes mellitus (T1DM), they fall short in addressing autoimmunity and regenerating damaged islets. This review aims to explore the potential and prospects of emerging treatment modalities for T1DM, including mesenchymal stem cells (MSCs), MSC-derived exosomes, gene therapy, islet allotransplantation, pancreatic islet cell transplantation, and teplizumab. We review emerging treatment modalities for T1DM, highlighting several promising strategies with varied mechanisms and outcomes. Mesenchymal stem cells demonstrate potential in modulating the immune response and preserving or restoring beta-cell function, although variability in sources and administration routes necessitates further standardization. Similarly, MSC-derived exosomes show promise in promoting beta-cell regeneration and immune regulation, supported by early-stage studies showing improved glucose homeostasis in animal models, albeit with limited clinical data. Gene therapy, utilizing techniques like CRISPR-Cas9, offers targeted correction of genetic defects and immune modulation; however, challenges in precise delivery and ensuring long-term safety persist. Islet allotransplantation and pancreatic islet cell transplantation have achieved some success in restoring insulin independence, yet challenges such as donor scarcity and immunosuppression-related complications remain significant. Teplizumab, an anti-CD3 monoclonal antibody, has demonstrated potential in delaying T1DM onset by modulating immune responses and preserving beta-cell function, with clinical trials indicating prolonged insulin production capability. Despite significant progress, standardization, long-term efficacy, and safety continue to pose challenges across these modalities. Conclusion: While these therapies demonstrate significant potential, challenges persist. Future research should prioritize optimizing these treatments and validating them through extensive clinical trials to enhance T1DM management and improve patient outcomes.

From pre-clinical efficacy to promising clinical trials that delay Type 1 diabetes.

Recent advancements in immunology and islet biology have unveiled remarkable prospects for the postponement of Type 1 diabetes (T1D) through the strategic modulation of the immune system. In this Perspective, we discuss the pharmaceutical strides achieved, traversing from pre-clinical validation to the execution of impactful clinical trials. We begin with the initial investigations involving cyclosporine and glucocorticoids in rodent models, such as the non-obese diabetic (NOD) mouse, which guided early clinical trials. We then discuss the pre-clinical studies using suitable mouse models that eventually led to contemporary clinical trials targeting immune cell functionality and cytokine signaling pathways. Collectively, these discoveries promote the exciting paradigm of immune system modulation to mitigate autoimmunity, which continues to broaden. Notably, the use of baricitinib, a potent JAK1/2 inhibitor, and teplizumab, an anti-CD3 monoclonal antibody, represent discrete methodologies converging upon a singular outcome: the preservation of islet beta-cell functionality. The latter interventional strategies build on the original idea that tempering specific facets of the immune system will generate therapeutic benefit. Enthusiasm from these discoveries stems from efficacy with reduced side effects when compared with past approaches. The success of therapeutic intervention(s) in pre-clinical studies, combined with knowledge about stages of progression to clinical T1D, have ultimately encouraged the design of more successful clinical trials targeting highly specific populations at risk. Collectively, these findings instill a profound sense of optimism, suggesting that the prevention and even reversal of T1D may soon be within reach.

Dysregulation of cholesterol homeostasis is an early signal of beta cell proteotoxicity characteristic of type 2 diabetes.

Type 2 diabetes (T2D) is a common metabolic disease due to insufficient insulin secretion by pancreatic beta cells in the context of insulin resistance. Islet molecular pathology reveals a role for protein misfolding in beta cell dysfunction and loss with islet amyloid derived from islet amyloid polypeptide (IAPP), a protein co-expressed and co-secreted with insulin. The most toxic form of misfolded IAPP is intracellular membrane disruptive toxic oligomers present in beta cells in T2D and in beta cells of mice transgenic for human IAPP (hIAPP). Prior work revealed a high degree of overlap of transcriptional changes in islets from T2D and pre-diabetic 9-10-week-old mice transgenic for hIAPP with most changes being pro-survival adaptations and therefore of limited therapeutic guidance. Here we investigated islets from hIAPP transgenic mice at an earlier age (6 weeks) to screen for potential mediators of hIAPP toxicity that precede predominance of pro-survival signaling. We identified early suppression of cholesterol synthesis and trafficking along with aberrant intra-beta cell cholesterol and lipid deposits, and impaired cholesterol trafficking to cell membranes. These findings align with comparable lipid deposits present in beta cells in T2D and increased vulnerability to develop T2D in individuals taking medications that suppress cholesterol synthesis.

Alternative therapeutic strategies in diabetes management.

Diabetes is a heterogeneous metabolic disease characterized by elevated blood glucose levels resulting from the destruction or malfunction of pancreatic ß cells, insulin resistance in peripheral tissues, or both, and results in a non-sufficient production of insulin. To adjust blood glucose levels, diabetic patients need exogenous insulin administration together with medical nutrition therapy and physical activity. With the aim of improving insulin availability in diabetic patients as well as ameliorating diabetes comorbidities, different strategies have been investigated. The first approaches included enhancing endogenous ß cell activity or transplanting new islets. The protocol for this kind of intervention has recently been optimized, leading to standardized procedures. It is indicated for diabetic patients with severe hypoglycemia, complicated by impaired hypoglycemia awareness or exacerbated glycemic lability. Transplantation has been associated with improvement in all comorbidities associated with diabetes, quality of life, and survival. However, different trials are ongoing to further improve the beneficial effects of transplantation. Furthermore, to overcome some limitations associated with the availability of islets/pancreas, alternative therapeutic strategies are under evaluation, such as the use of mesenchymal stem cells (MSCs) or induced pluripotent stem cells for transplantation. The cotransplantation of MSCs with islets has been successful, thus providing protection against proinflammatory cytokines and hypoxia through different mechanisms, including exosome release. The use of induced pluripotent stem cells is recent and requires further investigation. The advantages of MSC implantation have also included the improvement of diabetes-related comorbidities, such as wound healing. Despite the number of advantages of the direct injection of MSCs, new strategies involving biomaterials and scaffolds have been developed to improve the efficacy of mesenchymal cell delivery with promising results. In conclusion, this paper offered an overview of new alternative strategies for diabetes management while highlighting some limitations that will need to be overcome by future approaches.

Targeted mapping and utilization of the perihepatic surface for therapeutic beta cell replacement and retrieval in diabetic non-human primates.

Introduction: Successful diabetes reversal using pancreatic islet transplantation by various groups illustrates the significant achievements made in cell-based diabetes therapy. While clinically, intraportal islet delivery is almost exclusively used, it is not without obstacles, including instant blood-mediated inflammatory reaction (IBMIR), relative hypoxia, and loss of function over time, therefore hindering long-term success. Here we demonstrate the perihepatic surface of non-human primates (NHPs) as a potential islet delivery site maximizing favorable characteristics, including proximity to a dense vascular network for adequate oxygenation while avoiding IBMIR exposure, maintenance of portal insulin delivery, and relative ease of accessibility through minimally invasive surgery or percutaneous means. In addition, we demonstrate a targeted mapping technique of the perihepatic surface, allowing for the testing of multiple experimental conditions, including a semi-synthetic hydrogel as a possible three-dimensional framework to improve islet viability. Methods: Perihepatic allo-islet cell transplants were performed in immunosuppressed cynomolgus macaques using a targeted mapping technique to test multiple conditions for biocompatibility. Transplant conditions included islets or carriers (including hydrogel, autologous plasma, and media) alone or in various combinations. Necropsy was performed at day 30, and histopathology was performed to assess biocompatibility, immune response, and islet viability. Subsequently, single-injection perihepatic allo-islet transplant was performed in immunosuppressed diabetic cynomolgus macaques. Metabolic assessments were measured frequently (i.e., blood glucose, insulin, C-peptide) until final graft retrieval for histopathology. Results: Targeted mapping biocompatibility studies demonstrated mild inflammatory changes with islet-plasma constructs; however, significant inflammatory cell infiltration and fibrosis were seen surrounding sites with the hydrogel carrier affecting islet viability. In diabetic NHPs, perihepatic islet transplant using an autologous plasma carrier demonstrated prolonged function up to 6 months with improvements in blood glucose, exogenous insulin requirements, and HbA1c. Histopathology of these islets was associated with mild peri-islet mononuclear cell infiltration without evidence of rejection. Discussion: The perihepatic surface serves as a viable site for islet cell transplantation demonstrating sustained islet function through 6 months. The targeted mapping approach allows for the testing of multiple conditions simultaneously to evaluate immune response to biomaterials at this site. Compared to traditional intraportal injection, the perihepatic site is a minimally invasive approach that allows the possibility for graft recovery and avoids IBMIR.

XBP1 splicing contributes to endoplasmic reticulum stress-induced human islet amyloid polypeptide up-regulation.

As a pathological hallmark of type 2 diabetes mellitus (T2DM), islet amyloid is formed by the aggregation of islet amyloid polypeptide (IAPP). Endoplasmic reticulum (ER) stress interacts with IAPP aggregates and has been implicated in the pathogenesis of T2DM. To examine the role of ER stress in T2DM, we cloned the hIAPP promoter and analyzed its promoter activity in human ß-cells. We found that ER stress significantly enhanced hIAPP promoter activity and expression in human ß-cells via triggering X-box binding protein 1 (XBP1) splicing. We identified a binding site of XBP1 in the hIAPP promoter. Disruption of this binding site by substitution or deletion mutagenesis significantly diminished the effects of ER stress on hIAPP promoter activity. Blockade of XBP splicing by MKC3946 treatment inhibited ER stress-induced hIAPP up-regulation and improved human ß-cell survival and function. Our study uncovers a link between ER stress and IAPP at the transcriptional level and may provide novel insights into the role of ER stress in IAPP cytotoxicity and the pathogenesis of T2DM.

Rat Ductal Cell-Derived Differentiation into Islet-Like Cells.

Regenerative medicine investigates the conversion of pancreatic ductal cells into functional islet cells, offering innovative treatments for conditions such as diabetes. Ductal cells, primarily supporting the pancreas' exocrine functions, can differentiate into various cell types, including islet cells, under specific conditions, opening new avenues in research and therapy. The outlined protocol elaborates on the conversion process, covering ductal cell differentiation induction, and insulin-producing capacity assessment. The primary objective is to address the shortage of insulin-secreting cells for transplantation, thereby advancing diabetes treatment methodologies.

Scalable Generation of 3D Pancreatic Islet Organoids from Human Pluripotent Stem Cells in Suspension Bioreactors.

We describe a scalable method for the robust generation of 3D pancreatic islet-like organoids from human pluripotent stem cells using suspension bioreactors. Our protocol involves a 6-stage, 20-day directed differentiation process, resulting in the production of 104-105 organoids. These organoids comprise α- and ß-like cells that exhibit glucose-responsive insulin and glucagon secretion. We detail methods for culturing, passaging, and cryopreserving stem cells as suspended clusters and for differentiating them through specific growth media and exogenous factors added in a stepwise manner. Additionally, we address quality control measures, troubleshooting strategies, and functional assays for research applications.

tRNA-derived fragments in T lymphocyte-beta cell crosstalk and in type 1 diabetes pathogenesis in NOD mice.

AIMS/HYPOTHESIS: tRNAs play a central role in protein synthesis. Besides this canonical function, they were recently found to generate non-coding RNA fragments (tRFs) regulating different cellular activities. The aim of this study was to assess the involvement of tRFs in the crosstalk between immune cells and beta cells and to investigate their contribution to the development of type 1 diabetes. METHODS: Global profiling of the tRFs present in pancreatic islets of 4- and 8-week-old NOD mice and in extracellular vesicles released by activated CD4+ T lymphocytes was performed by small RNA-seq. Changes in the level of specific fragments were confirmed by quantitative PCR. The transfer of tRFs from immune cells to beta cells occurring during insulitis was assessed using an RNA-tagging approach. The functional role of tRFs increasing in beta cells during the initial phases of type 1 diabetes was determined by overexpressing them in dissociated islet cells and by determining the impact on gene expression and beta cell apoptosis. RESULTS: We found that the tRF pool was altered in the islets of NOD mice during the initial phases of type 1 diabetes. Part of these changes were triggered by prolonged exposure of beta cells to proinflammatory cytokines (IL-1ß, TNF-α and IFN-γ) while others resulted from the delivery of tRFs produced by CD4+ T lymphocytes infiltrating the islets. Indeed, we identified several tRFs that were enriched in extracellular vesicles from CD4+/CD25- T cells and were transferred to beta cells upon adoptive transfer of these immune cells in NOD.SCID mice. The tRFs delivered to beta cells during the autoimmune reaction triggered gene expression changes that affected the immune regulatory capacity of insulin-secreting cells and rendered the cells more prone to apoptosis. CONCLUSIONS/INTERPRETATION: Our data point to tRFs as novel players in the crosstalk between the immune system and insulin-secreting cells and suggest a potential involvement of this novel class of non-coding RNAs in type 1 diabetes pathogenesis. DATA AVAILABILITY: Sequences are available from the Gene Expression Omnibus (GEO) with accession numbers GSE242568 and GSE256343.

The SWI/SNF chromatin remodelling complex regulates pancreatic endocrine cell expansion and differentiation in mice in vivo.

AIMS/HYPOTHESIS: Strategies to augment functional beta cell mass include directed differentiation of stem cells towards a beta cell fate, which requires extensive knowledge of transcriptional programs governing endocrine progenitor cell differentiation in vivo. We aimed to study the contributions of the Brahma-related gene-1 (BRG1) and Brahma (BRM) ATPase subunits of the SWI/SNF chromatin remodelling complex to endocrine cell development. METHODS: We generated mice with endocrine progenitor-specific Neurog3-Cre BRG1 removal in the presence of heterozygous (Brg1Δendo;Brm+/-) or homozygous (double knockout: DKOΔendo) BRM deficiency. Whole-body metabolic phenotyping, islet function characterisation, islet quantitative PCR and histological characterisation were performed on animals and tissues postnatally. To test the mechanistic actions of SWI/SNF in controlling gene expression during endocrine cell development, single-cell RNA-seq was performed on flow-sorted endocrine-committed cells from embryonic day 15.5 control and mutant embryos. RESULTS: Brg1Δendo;Brm+/- mice exhibit severe glucose intolerance, hyperglycaemia and hypoinsulinaemia, resulting, in part, from reduced islet number; diminished alpha, beta and delta cell mass; compromised islet insulin secretion; and altered islet gene expression programs, including reductions in MAFA and urocortin 3 (UCN3). DKOΔendo mice were not recovered at weaning; however, postnatal day 6 DKOΔendo mice were severely hyperglycaemic with reduced serum insulin levels and beta cell area. Single-cell RNA-seq of embryonic day 15.5 lineage-labelled cells revealed endocrine progenitor, alpha and beta cell populations from SWI/SNF mutants have reduced expression of Mafa, Gcg, Ins1 and Ins2, suggesting limited differentiation capacity. Reduced Neurog3 transcripts were discovered in DKOΔendo endocrine progenitor clusters, and the proliferative capacity of neurogenin 3 (NEUROG3)+ cells was reduced in Brg1Δendo;Brm+/- and DKOΔendo mutants. CONCLUSIONS/INTERPRETATION: Loss of BRG1 from developing endocrine progenitor cells has a severe postnatal impact on glucose homeostasis, and loss of both subunits impedes animal survival, with both groups exhibiting alterations in hormone transcripts embryonically. Taken together, these data highlight the critical role SWI/SNF plays in governing gene expression programs essential for endocrine cell development and expansion. DATA AVAILABILITY: Raw and processed data for scRNA-seq have been deposited into the NCBI Gene Expression Omnibus (GEO) database under the accession number GSE248369.

Diabetes current and future translatable therapies.

Diabetes is one of the major diseases and concerns of public health systems that affects over 200 million patients worldwide. It is estimated that 90% of these patients suffer from diabetes type 2, while 10% present diabetes type 1. This type of diabetes and certain types of diabetes type 2, are characterized by dysregulation of blood glycemic levels due to the total or partial depletion of insulin-secreting pancreatic ß-cells. Different approaches have been proposed for long-term treatment of insulin-dependent patients; amongst them, cell-based approaches have been the subject of basic and clinical research since they allow blood glucose level sensing and in situ insulin secretion. The current gold standard for insulin-dependent patients is on-demand exogenous insulin application; cell-based therapies aim to remove this burden from the patient and caregivers. In recent years, protocols to isolate and implant pancreatic islets from diseased donors have been developed and tested in clinical trials. Nevertheless, the shortage of donors, along with the need of immunosuppressive companion therapies, have pushed researchers to focus their attention and efforts to overcome these disadvantages and develop alternative strategies. This review discusses current tested clinical approaches and future potential alternatives for diabetes type 1, and some diabetes type 2, insulin-dependent patients. Additionally, advantages and disadvantages of these discussed methods.

Decreased islet amyloid polypeptide staining in the islets of insulinoma patients.

Islet amyloid polypeptide (IAPP) is a factor that regulates food intake and is secreted from both pancreatic islets and insulinoma cells. Here, we aimed to evaluate IAPP immunohistochemically in islets or insulinoma cells in association with clinical characteristics. We recruited six insulinoma patients and six body mass index-matched control patients with pancreatic diseases other than insulinoma whose glucose tolerance was confirmed to be normal preoperatively. IAPP and IAPP-insulin double staining were performed on pancreatic surgical specimens. We observed that the IAPP staining level and percentage of IAPP-positive beta cells tended to be lower (p = 0.1699) in the islets of insulinoma patients than in those of control patients, which might represent a novel IAPP expression pattern under persistent hyperinsulinemia and hypoglycemia.

Pancreatic stellate cells support human pancreatic ß-cell viability in vitro and enhance survival of immunoisolated human islets exposed to cytokines.

Pancreatic islet transplantation is proposed as a cure for type 1 diabetes mellitus (T1D). Despite its success in optimal regulation of glucose levels, limitations in longevity of islet grafts still require innovative solutions. Inflammatory stress post-transplantation and loss of extracellular matrix attribute to the limited ß-cell survival. Pancreatic stellate cells (PSCs), identified as pancreatic-specific stromal cells, have the potential to play a crucial role in preserving islet survival. Our study aimed to determine the effects of PSCs co-cultured with human CM ß-cells and human islets under inflammatory stress induced by a cytokine cocktail of IFN-γ, TNF-α and IL-1ß. Transwell culture inserts were utilized to assess the paracrine impact of PSCs on ß-cells, alongside co-cultures enabling direct interaction between PSCs and human islets. We found that co-culturing PSCs with human CM ß-cells and human cadaveric islets had rescuing effects on cytokine-induced stress. Effects were different under normoglycemic and hyperglycemic conditions. PSCs were associated with upregulation of ß-cell mitochondrial activity and suppression of inflammatory gene expression. The rescuing effects exist both in indirect and direct co-culture methods. Furthermore, we tested whether PSCs have rescuing effects on human islets in conventional alginate-based microcapsules and in composite microcapsules composed of alginate-pectin collagen type IV, laminin sequence RGD, Nec-1, and amino acid. PSCs partially prevented cytokine-induced stress in both systems, but beneficial effects were stronger in composite capsules. Our findings show novel effects of PSCs on islet health. Islets and PSCs coculturing or co-transplantation might mitigate the inflammation stress and improve islet transplantation outcomes.