Restoration Of Β-cell Function Research Articles

Real-world effectiveness of early insulin therapy on the incidence of cardiovascular events in newly diagnosed type 2 diabetes

Early insulin therapy is capable to achieve glycemic control and restore β-cell function in newly diagnosed type 2 diabetes (T2D), but its effect on cardiovascular outcomes in these patients remains unclear. In this nationwide real-world study, we analyzed electronic health record data from 19 medical centers across China between 1 January 2000, and 26 May 2022. We included 5424 eligible patients (mean age 56 years, 2176 women/3248 men) who were diagnosed T2D within six months and did not have prior cardiovascular disease. Multivariable Cox regression models were used to estimate the associations of early insulin therapy (defined as the first-line therapy for at least two weeks in newly diagnosed T2D patients) with the incidence of major cardiovascular events including coronary heart disease (CHD), stroke, and hospitalization for heart failure (HF). During 17,158 persons years of observation, we documented 834 incident CHD cases, 719 stroke cases, and 230 hospitalized cases for HF. Newly diagnosed T2D patients who received early insulin therapy, compared with those who did not receive such treatment, had 31% lower risk of incident stroke, and 28% lower risk of hospitalization for HF. No significant difference in the risk of CHD was observed. We found similar results when repeating the aforesaid analysis in a propensity-score matched population of 4578 patients and with inverse probability of treatment weighting models. These findings suggest that early insulin therapy in newly diagnosed T2D may have cardiovascular benefits by reducing the risk of incident stroke and hospitalization for HF.

Nrf2 inhibition regulates intracellular lipid accumulation in mouse insulinoma cells and improves insulin secretory function

High amount of fat in the pancreas is linked to poor functioning of β-cells and raises the risk of type 2 diabetes. Here we report the putative role of a circulatory glycoprotein Fetuin-A, a known obesity marker, in promoting lipid accumulation in β-cells and its association with Fatty acid translocase/CD36 for lipid storage culminate in β-cell dysfunction. Additionally, this work reveals regulation of CD36 via Nrf2, a key regulator of oxidative stress, and reduction of lipid accumulation by suppression of Nrf2 that restores β-cell function. Palmitate (0.50 mM) and Fetuin-A (100 μg/mL) exposure showed high levels of intracellular lipid in MIN6 (mouse insulinoma cells) with a concomitant decrease in insulin secretion. This also increased the expression of important lipogenic factors, like CD36, PGC1α, PPARγ, and SREBP1. Flow cytometry analysis of CD36 membrane localization has been corroborated with an increased accumulation of lipids as indicated by Oil-Red-O staining. Immunoblotting and immunofluorescence of Nrf2 indicated its high expression in palmitate-fetuin-A incubation and translocation in the nucleus. Suppression of Nrf2 by siRNA showed a reduced expression of lipogenic genes, ablation of lipid droplets, decrease in the number of apoptotic cells, and restoration of insulin secretion with a corresponding increase of Pdx1, BETA2, and Ins1 gene expression. Our study thus suggested an important aspect of lipid accumulation in the pancreatic β-cells contributing to β-cell dysfunction and demonstrated the role of Fetuin-A in CD36 expression, with a possible way of restoring β-cell function by targeting Nrf2.

Decreased IGF1R attenuates senescence and improves function in pancreatic β-cells.

The enhanced β-cell senescence that accompanies insulin resistance and aging contributes to cellular dysfunction and loss of transcriptional identity leading to type 2 diabetes (T2D). While senescence is among the 12 recognized hallmarks of aging, its relation to other hallmarks including altered nutrient sensing (insulin/IGF1 pathway) in β-cells is not fully understood. We previously reported that an increased expression of IGF1R in mouse and human β-cells is a marker of older β-cells; however, its contribution to age-related dysfunction and cellular senescence remains to be determined. In this study, we explored the direct role of IGF1R in β-cell function and senescence using two independent mouse models with decreased IGF1/IGF1R signaling: a) Ames Dwarf mice (Dwarf +/+), which lack growth hormone and therefore have reduced circulating levels of IGF1, and b) inducible β-cell-specific IGF1R knockdown (βIgf1rKD) mice. Compared to Dwarf+/- mice, Dwarf+/+ mice had lower body and pancreas weight, lower circulating IGF1 and insulin levels, and lower IGF1R and p21Cip1 protein expression in β-cells, suggesting the suppression of senescence. Adult βIgf1rKD mice showed improved glucose clearance and glucose-induced insulin secretion, accompanied by decreased p21Cip1 protein expression in β-cells. RNA-Seq of islets isolated from these βIgf1rKD mice revealed the restoration of three signaling pathways known to be downregulated by aging: sulfide oxidation, autophagy, and mTOR signaling. Additionally, deletion of IGF1R in mouse β-cells increased transcription of genes important for maintaining β-cell identity and function, such as Mafa, Nkx6.1, and Kcnj11, while decreasing senescence-related genes, such as Cdkn2a, Il1b, and Serpine 1. Decreased senescence and improved insulin-secretory function of β-cells were also evident when the βIgf1rKD mice were fed a high-fat diet (HFD; 60% kcal from fat, for 5 weeks). These results suggest that IGF1R signaling plays a causal role in aging-induced β-cell dysfunction. Our data also demonstrate a relationship between decreased IGF1R signaling and suppressed cellular senescence in pancreatic β-cells. Future studies can further our understanding of the interaction between senescence and aging, developing interventions that restore β-cell function and identity, therefore preventing the progression to T2D.

Recent trends and advances in type 1 diabetes therapeutics: A comprehensive review

Type 1 diabetes (T1D) is a chronic autoimmune disease characterized by the destruction of pancreatic β-cells, leading to insulin deficiency. Insulin replacement therapy is the current standard of care for T1D, but it has significant limitations. However, stem cell-based replacement therapy has the potential to restore β-cell function and achieve glycaemic control eradicating the necessity for drugs or injecting insulin externally. While significant progress has been made in preclinical studies, the clinical translation of stem cell therapy for T1D is still in its early stages. In continuation, further research is essentially required to determine the safety and efficacy of stem cell therapies and to develop strategies to prevent immune rejection of stem cell-derived β-cells. The current review highlights the current state of cellular therapies for T1D including, different types of stem cell therapies, gene therapy, immunotherapy, artificial pancreas, and cell encapsulation being investigated, and their potential for clinical translation.

β-Cell Function and Insulin Dynamics in Obese Patients With and Without Diabetes After Sleeve Gastrectomy.

Improved β-cell function seems to be essential for better glucose homeostasis after Roux-en-Y gastric bypass but is less studied after sleeve gastrectomy (SG). We evaluated the effects of SG on β- cell function in obese patients with diabetes (DM group) and without (Control group) in response to both oral and intravenous glucose stimulation. The DM group demonstrated impaired insulin sensitivity and insulin response to glucose before surgery. The insulin sensitivity index of both groups significantly improved after SG. In addition, the insulin response to glucose (early insulinogenic index in OGTT and AIRglu in IVGTT) increased in the DM group but decreased in the Control group. As a result, β-cell function improved significantly in both groups after SG since the disposition index (DI) increased in both. However, the DI of DM group still can't restore to the level of Control group up to 1 year after SG. Our results support that both obese patients with and without diabetes could benefit from SG in β-cell function. For obese patients at risk of or have been diagnosed with diabetes, interventions should be recommended early to preserve or restore β-cell function, and SG could be an effective choice. Further studies are needed for long-term effects.

Glucagon-Like Peptide-1 Receptor Agonists in Primary Care: Beyond Glycemic Control

Type 2 diabetes (T2D) is no longer considered solely a glucose-centric condition, but rather a chronic cardiometabolic disease that is linked to premature cardiovascular and renal complications and early death. Whereas previously, the level of glycemic control drove management decisions regarding treatment intensification, healthcare providers now have newer classes of agents that not only effectively lower glucose levels but also reduce the long-term risk of cardiovascular and renal complications. Glucagon-like peptide-1 receptor agonists (GLP-1RAs) address several of the progressive multiorgan dysfunctions associated with T2D and a number of GLP-1RAs have been shown to reduce the risk of major adverse cardiovascular events in people with established cardiovascular disease or in those at high cardiovascular risk; GLP-1RAs (or a cardioprotective sodium-glucose cotransporter-2 inhibitor) should be considered in these high-risk patients regardless of their glycated hemoglobin goal attainment status. GLP-1RAs also facilitate substantial weight loss and there is some evidence that they may help to restore β-cell function and slow the decline of kidney function, although further studies are needed to confirm this.

Glucagon-Like Peptide-1 Receptor Agonists in Primary Care: Beyond Glycemic Control

Type 2 diabetes (T2D) is no longer considered solely a glucosecentric condition, but rather a chronic cardiometabolic disease that is linked to premature cardiovascular and renal complications and early death. Whereas previously, the level of glycemic control drove management decisions regarding treatment intensification, healthcare providers now have newer classes of agents that not only effectively lower glucose levels but also reduce the long-term risk of cardiovascular and renal complications. Glucagon-like peptide- 1 receptor agonists (GLP-1RAs) address several of the progressive multiorgan dysfunctions associated with T2D and a number of GLP-1RAs have been shown to reduce the risk of major adverse cardiovascular events in people with established cardiovascular disease or in those at high cardiovascular risk; GLP-1RAs (or a cardioprotective sodium-glucose cotransporter-2 inhibitor) should be considered in these high-risk patients regardless of their glycated hemoglobin goal attainment status. GLP-1RAs also facilitate substantial weight loss and there is some evidence that they may help to restore β-cell function and slow the decline of kidney function, although further studies are needed to confirm this.

Calcineurin/NFATc2 and PI3K/AKT signaling maintains β-cell identity and function during metabolic and inflammatory stress

SummaryPancreatic islets respond to metabolic and inflammatory stress by producing hormones and other factors that induce adaptive cellular and systemic responses. Here we show that intracellular Ca2+ ([Ca2+]i) and ROS signals generated by high glucose and cytokine-induced ER stress activate calcineurin (CN)/NFATc2 and PI3K/AKT to maintain β-cell identity and function. This was attributed in part by direct induction of the endocrine differentiation gene RFX6 and suppression of several β-cell “disallowed” genes, including MCT1. CN/NFATc2 targeted p300 and HDAC1 to RFX6 and MCT1 promoters to induce and suppress gene transcription, respectively. In contrast, prolonged exposure to stress, hyperstimulated [Ca2+]i, or perturbation of CN/NFATc2 resulted in downregulation of RFX6 and induction of MCT1. These findings reveal that CN/NFATc2 and PI3K/AKT maintain β-cell function during acute stress, but β-cells dedifferentiate to a dysfunctional state upon loss or exhaustion of Ca2+/CN/NFATc2 signaling. They further demonstrate the utility of targeting CN/NFATc2 to restore β-cell function

SGLT2 inhibitors therapy protects glucotoxicity-induced β-cell failure in a mouse model of human KATP-induced diabetes through mitigation of oxidative and ER stress.

Progressive loss of pancreatic β-cell functional mass and anti-diabetic drug responsivity are classic findings in diabetes, frequently attributed to compensatory insulin hypersecretion and β-cell exhaustion. However, loss of β-cell mass and identity still occurs in mouse models of human KATP-gain-of-function induced Neonatal Diabetes Mellitus (NDM), in the absence of insulin secretion. Here we studied the temporal progression and mechanisms underlying glucotoxicity-induced loss of functional β-cell mass in NDM mice, and the effects of sodium-glucose transporter 2 inhibitors (SGLT2i) therapy. Upon tamoxifen induction of transgene expression, NDM mice rapidly developed severe diabetes followed by an unexpected loss of insulin content, decreased proinsulin processing and increased proinsulin at 2-weeks of diabetes. These early events were accompanied by a marked increase in β-cell oxidative and ER stress, without changes in islet cell identity. Strikingly, treatment with the SGLT2 inhibitor dapagliflozin restored insulin content, decreased proinsulin:insulin ratio and reduced oxidative and ER stress. However, despite reduction of blood glucose, dapagliflozin therapy was ineffective in restoring β-cell function in NDM mice when it was initiated at >40 days of diabetes, when loss of β-cell mass and identity had already occurred. Our data from mouse models demonstrate that: i) hyperglycemia per se, and not insulin hypersecretion, drives β-cell failure in diabetes, ii) recovery of β-cell function by SGLT2 inhibitors is potentially through reduction of oxidative and ER stress, iii) SGLT2 inhibitors revert/prevent β-cell failure when used in early stages of diabetes, but not when loss of β-cell mass/identity already occurred, iv) common execution pathways may underlie loss and recovery of β-cell function in different forms of diabetes. These results may have important clinical implications for optimal therapeutic interventions in individuals with diabetes, particularly for those with long-standing diabetes.

Increased glycolysis affects β-cell function and identity in aging and diabetes

ObjectiveAge is a risk factor for type 2 diabetes (T2D). We aimed to elucidate whether β-cell glucose metabolism is altered with aging and contributes to T2D. MethodsWe used senescence-accelerated mice (SAM), C57BL/6J (B6) mice, and ob/ob mice as aging models. As a diabetes model, we used db/db mice. The glucose responsiveness of insulin secretion and the [U-13C]-glucose metabolic flux were examined in isolated islets. We analyzed the expression of β-cell-specific genes in isolated islets and pancreatic sections as molecular signatures of β-cell identity. β cells defective in the malate-aspartate (MA) shuttle were previously generated from MIN6-K8 cells by the knockout of Got1, a component of the shuttle. We analyzed Got1 KO β cells as a model of increased glycolysis. ResultsWe identified hyperresponsiveness to glucose and compromised cellular identity as dysfunctional phenotypes shared in common between aged and diabetic mouse β cells. We also observed a metabolic commonality between aged and diabetic β cells: hyperactive glycolysis through the increased expression of nicotinamide mononucleotide adenylyl transferase 2 (Nmnat2), a cytosolic nicotinamide adenine dinucleotide (NAD)-synthesizing enzyme. Got1 KO β cells showed increased glycolysis, β-cell dysfunction, and impaired cellular identity, phenocopying aging and diabetes. Using Got1 KO β cells, we show that attenuation of glycolysis or Nmnat2 activity can restore β-cell function and identity. ConclusionsOur study demonstrates that hyperactive glycolysis is a metabolic signature of aged and diabetic β cells, which may underlie age-related β-cell dysfunction and loss of cellular identity. We suggest Nmnat2 suppression as an approach to counteract age-related T2D.

Vertical sleeve gastrectomy triggers fast β-cell recovery upon overt diabetes

ObjectiveThe effectiveness of bariatric surgery in restoring β-cell function has been described in type-2 diabetes (T2D) patients and animal models for years, whereas the mechanistic underpinnings are largely unknown. The possibility of vertical sleeve gastrectomy (VSG) to rescue far-progressed, clinically-relevant T2D and to promote β-cell recovery has not been investigated on a single-cell level. Nevertheless, characterization of the heterogeneity and functional states of β-cells after VSG is a fundamental step to understand mechanisms of glycaemic recovery and to ultimately develop alternative, less-invasive therapies. MethodsWe performed VSG in late-stage diabetic db/db mice and analyzed the islet transcriptome using single-cell RNA sequencing (scRNA-seq). Immunohistochemical analyses and quantification of β-cell area and proliferation complement our findings from scRNA-seq. ResultsWe report that VSG was superior to calorie restriction in late-stage T2D and rapidly restored normoglycaemia in morbidly obese and overt diabetic db/db mice. Single-cell profiling of islets of Langerhans showed that VSG induced distinct, intrinsic changes in the β-cell transcriptome, but not in that of α-, δ-, and PP-cells. VSG triggered fast β-cell redifferentiation and functional improvement within only two weeks of intervention, which is not seen upon calorie restriction. Furthermore, VSG expanded β-cell area by means of redifferentiation and by creating a proliferation competent β-cell state. ConclusionCollectively, our study reveals the superiority of VSG in the remission of far-progressed T2D and presents paths of β-cell regeneration and molecular pathways underlying the glycaemic benefits of VSG.

Specific Naturopathic Modalities Ameliorate Glucose Homeostasis and Other Physiological Parameters in Human Diabetics

Background: Diabetes Mellitus is now becoming a serious medical and socio-economic issue all over the world. Early initiation of combination therapy has been suggested as a way to achieve glycemic control, postpone the complications and possibly restore β-cell function. Naturopathy and yoga is one of the upcoming medical systems which had showed a promising result for many lifestyle disorders and hence, this study was aimed to evaluate the effect of 10 days Integrated Naturopathy and Yoga (INY) treatment especially Abdomen Massage and Neutral Hip Bath on glycemic control and anthropometric measures.
 Methods: 100 subjects with diabetes were selected and randomly allocated into Case group (naturopathy & yoga intervention with Abdomen Massage and Neutral Hip Bath) and Control group (naturopathy & yoga intervention). The subjects were assessed for blood glucose levels and anthropometric measures at baseline and after the intervention of 10 days.
 Results: The result of this study showed a significant reduction in Fasting Glucose (FG) and Post Prandial Glucose (PPG) after 10 days of intervention where Body Mass Index (BMI) and Waist Hip Ratio (WHR) have not shown significant changes in the groups. The case group has a larger mean difference between pre and post values of FG, PPG, BMI, and WHR as compared to the control group.
 Conclusion: Abdomen massage with neutral hip bath is relatively better for lowering the FG, PPG along with BMI and WHR, by the activation of adiponectin, Brown Adipose Tissue, Atrial natriuretic peptide and counter-regulatory stress hormones, which control hormonal activity, glucose absorption, metabolism and excretion.

Alleviation of diabetes mellitus through the restoration of β-cell function and lipid metabolism by Aloe vera (L.) Burm. f. extract in obesogenic WNIN/GR-Ob rats

Ethnopharmacological relevanceAloe vera (L.) Burm. f. extract has been medicinally used for over 5000 years in different cultures for its curative and therapeutic properties ranging from dermatitis to diabetes. It has been demonstrated to alleviate diabetes through its protective effects on pancreatic islets and by improving insulin secretion. Aim of the studyTo investigate the simultaneous effect of ethanolic A. vera gel extract on diabetes and obesogenic milieu in Streptozotocin-induced WNIN/GR-Ob mutant obese rats. Materials and methodsA total of 30 rats were grouped equally into WNIN/GR-Ob control (received water as a vehicle), WNIN/GR-Ob Diabetic rats (Streptozotocin-35 mg/kg bw), WNIN/GR-Ob Diabetic rats + Sitagliptin (10 mg/kg bw), WNIN/GR-Ob Diabetic rats + A. vera (300 mg/kg bw) and GR-Ob control + A. vera (300 mg/kg bw). After 4 weeks of treatment, fasting blood glucose, serum insulin, Homeostatic Model Assessment - Insulin Resistance and β-cell function, glucose-stimulated insulin secretion, Dipeptidyl peptidase-IV activity, and lipid profiles were studied. In addition, ultrastructural analysis of isolated islets and dual-energy X-ray absorptiometry analysis for body composition were also carried out. ResultsThe A. vera treated group showed a significant reduction (p < 0.05) in triglyceride, Very low-density lipoprotein levels, Triglyceride to High-density lipoprotein ratio as well as fasting blood glucose levels and DPP-IV activity with a concomitant increase in the serum insulin levels. The increase in IR was observed in both WNIN/GR-Ob control and diabetic rats with a significant decrease in β-cell function in the diabetic rats as per Homeostatic Model Assessment values. Oral administration of A. vera was effective in both reducing Homeostatic Model Assessment-Insulin Resistance and increasing Homeostatic Model Assessment-β values. Also, the treated group demonstrated preservation of islets and a significant increase (p < 0.05) in the diameter of β-cell as evident through Scanning electron microscope analysis. The increase in lean body mass was manifested in the treated group with a reduction in Fat percent in comparison with other groups. ConclusionThe beneficial effects of A. vera in WNIN/GR-Ob strain may be attributed to its ability to lower lipid profile thus improve insulin sensitivity and/or modulating β-cell function. Thus, it has great therapeutic potential as an herbal remedy for the treatment of diabetes and associated adverse effects such as obesity. The exact mechanism underlying the observation needs to be investigated further to explore the anti-obesity and anti-diabetic properties of A. vera and advocate its potential application as alternative medicine.

Cigarette smoke exposure impairs β-cell function through activation of oxidative stress and ceramide accumulation

ObjectivesEpidemiological studies indicate that first- and second-hand cigarette smoke (CS) exposure are important risk factors for the development of type 2 diabetes (T2D). Additionally, elevated diabetes risk has been reported to occur within a short period of time after smoking cessation, and health risks associated with smoking are increased when combined with obesity. At present, the mechanisms underlying these associations remain incompletely understood. The objective of this study was to test the impact of CS exposure on pancreatic β-cell function using rodent and in vitro models. MethodsBeginning at 8 weeks of age, C57BL/6 J mice were concurrently fed a high-fat diet (HFD) and exposed to CS for 11 weeks, followed by an additional 11 weeks of smoking cessation with continued HFD. Glucose tolerance testing was performed during CS exposure and during the cessation period. Cultured INS-1 β-cells and primary islets were exposed ex vivo to CS extract (CSE), and β-cell function and viability were tested. Since CS increases ceramide accumulation in the lung and these bioactive sphingolipids have been implicated in pancreatic β-cell dysfunction in diabetes, islet and β-cell sphingolipid levels were measured in islets from CS-exposed mice and in CSE-treated islets and INS-1 cells using liquid chromatography-tandem mass spectrometry. ResultsCompared to HFD-fed, ambient air-exposed mice, HFD-fed and CS-exposed mice had reduced weight gain and better glucose tolerance during the active smoking period. Following smoking cessation, CS-mice exhibited rapid weight gain and had accelerated worsening of their glucose tolerance. CS-exposed mice had higher serum proinsulin/insulin ratios, indicative of β-cell dysfunction, significantly lower β-cell mass (p = 0.017), reduced β-cell proliferation (p = 0.006), and increased islet ceramide content compared to non-smoking control mice. Ex vivo exposure of isolated islets to CSE was sufficient to increase islet ceramide levels, which was correlated with reduced insulin gene expression and glucose-stimulated insulin secretion, and increased β-cell oxidative and endoplasmic reticulum (ER) stress. Treatment with the antioxidant N-acetylcysteine markedly attenuated the effects of CSE on ceramide levels, restored β-cell function and survival, and increased cyclin D2 expression, while also reducing activation of β-cell ER and oxidative stress. ConclusionsOur results indicate that CS exposure leads to impaired insulin production, processing, secretion and reduced β-cell viability and proliferation. These effects were linked to increased β-cell oxidative and ER stress and ceramide accumulation. Mice fed HFD continued to experience detrimental effects of CS exposure even during smoking cessation. Elucidation of the mechanisms by which CS exposure impairs β-cell function in synergy with obesity will help design therapeutic and preventive interventions for both active and former smokers.

More is better: combinatorial therapy to restore β-cell function in diabetes.

Current pharmacological options for diabetes treatment help patients control blood glucose levels but do not reverse the decline in insulin-secreting β-cells. A new study now shows that a pharmacological combination of insulin and a GLP-1–oestrogen conjugate not only decreases daily insulin requirements but also improves β-cell function.

Therapeutic efficacy and safety of initial triple combination of metformin, sitagliptin, and lobeglitazone in drug-naïve patients with type 2 diabetes: initial triple study

ObjectiveTo compare the efficacy and safety of an initial triple therapy using metformin, a dipeptidyl peptidase-4 (DPP4) inhibitor, and thiazolidinedione with a stepwise approach using sulfonylurea and metformin in new-onset,...

Dracorhodin perchlorate protects pancreatic β-cells against glucotoxicity- or lipotoxicity-induced dysfunction and apoptosis invitro and invivo.

Glucotoxicity or lipotoxicityleads to hyperglycemia and insulin secretion deficiency, which are important causes for the onset of type 2 diabetes mellitus (T2DM). Thus, the restoration of β-cell function is a long-sought goal in diabetes research. Previous studies have implicated pancreatic and duodenal homeobox 1 gene (Pdx1) in β-cell function and insulin secretion. In this study, we established a Pdx1 promoter-dependent luciferase system and identified the natural compound dracorhodin perchlorate (DP) as an effective promotor of Pdx1 expression. We further demonstrated that DP could significantly inhibit β-cell apoptosis induced by 33mm glucose or 200 μm palmitate by interfering with endoplasmic reticulum stress and mitochondrial pathways and enhance insulin secretion as well. These effects were associated with enhanced activities of Erk1/2, which in turn promoted Pdx1 expression and increased the ratio of Bcl2/Bax, since inhibition of the Erk1/2 pathway abolished the DP-induced expression of Pdx1 and suppression of apoptosis. In addition, our invivo results in diabetic mice indicated that DP treatment lowered blood glucose, raised insulin levels, enhanced Pdx1 expression and increased islet size and number in the pancreas of diabetic mice. Our findings suggest that Pdx1 is a potential target molecule of DP in the treatment of T2DM via the inhibition ofglucotoxicity- or lipotoxicity- induced β-cell apoptosis and the attenuation of insulin secretion dysfunction.

Recent progress in porcine islet isolation, culture and engraftment strategies for xenotransplantation.

Xenotransplantation of porcine islets is a realistic option to restore β-cell function in type 1 diabetic patients. Among other factors, such as islet donor age (fetal, neonatal and adult) and genotype (wild type and genetically modified), choice of the transplantation site, and immune protection of the islets, efficient strategies for islet isolation, culture and engraftment are critical for the success of islet xenotransplantation. Neonatal porcine islets (NPIs) are immature at isolation and need to be matured in vitro or in vivo before they become fully functional. Recent developments include a scalable protocol for isolation of clinically relevant batches of NPIs and a stepwise differentiation protocol for directed maturation of NPIs. In addition, different sources of mesenchymal stem cells were shown to support survival and functional maturation of NPIs in vitro and in various transplantation models in vivo. A plethora of different culture media and supplements have been tested; however, a unique best culture system for NPIs is still missing. New insights, for example from single-cell analyses of islets or from stem cell differentiation toward β cells may help to optimize culture of porcine islets for xenotransplantation in an evidence-based manner.

Tannic Acid–Encapsulated Islets Suppress Autoimmunity and Restore Euglycemia following Transplantation

Type 1 diabetes (T1D) is an autoimmune disease of pancreatic β-cell death caused by islet-infiltrating leukocytes. Islet transplantation can restore β-cell function, however, limited islet availability, toxicity of immunosuppressants, and poor graft survival are major hurdles for clinical application. We hypothesize that islet encapsulation with a nanothin multilayer coating consisting of tannic acid (TA), an immunomodulatory antioxidant, and poly(N-vinylpyrrolidone) (PVPON), will provide an immunoprotective barrier and maintain β-cell function after transplantation. In support of our hypothesis, we demonstrate that (PVPON/TA)-encapsulated syngeneic NOD.Rag islets restored euglycemia after transplantation under the kidney capsule of streptozotocin-treated diabetic NOD mice by more than 30 days in comparison to non-encapsulated islets. Encapsulated allogeneic B6 islets also restored euglycemia in diabetic NOD mice and delayed rejection by 7.5 days in contrast to non-encapsulated islets. Gene expression of allogeneic B6 islets at 5 days post-transplant displayed an increase in Ins2 (6-fold), Gcg (6-fold), Pdx1 (5-fold), Ccl22 (3-fold), and Arg1 (2.5-fold) mRNA accumulation with (PVPON/TA)-encapsulated islet grafts, suggesting a potential shift toward an alternatively-activated M2 macrophage phenotype. To address limited islet availability, the use of (PVPON/TA)-encapsulated differentiated neonatal porcine islets restored euglycemia and maintained β-cell function for more than 200 days after transplantation into diabetic NOD.scid mice. Our results support the hypothesis that islet encapsulation with (PVPON/TA) coatings maintain function and may elicit protection following islet allo- and xenotransplantation. Future studies will determine the immunological mechanism of protection following (PVPON/TA)-encapsulation of islets. Disclosure J. Barra: None. H.M. Tse: None.

Tannic acid-encapsulated islets delay immune rejection following transplantation

Abstract Islet transplantation can restore β-cell function in patients with Type 1 diabetes (T1D), however, limited islet availability, toxicity of immunosuppressants, and poor graft survival are major hurdles for clinical application. We hypothesize that islet encapsulation with a nanothin multilayer coating consisting of tannic acid (TA), an immunomodulatory antioxidant, and poly(N-vinylpyrrolidone) (PVPON), will provide an immunoprotective barrier and maintain β-cell function after transplantation. (PVPON/TA)-encapsulated syngeneic NOD.Rag islets restored euglycemia after transplantation under the kidney capsule of streptozotocin-treated diabetic NOD mice by more than 30 days in comparison to non-encapsulated islets. Allogeneic encapsulated B6 islets also restored euglycemia in diabetic NOD recipients and delayed rejection by 7.5 days in contrast to non-encapsulated islets. Gene expression of allogeneic B6 islets at 5 days post-transplant displayed an increase in Ins2 (6-fold), Gcg (6-fold), Pdx1 (5-fold), Ccl22 (3-fold), and Arg1 (2.5-fold) mRNA accumulation with (PVPON/TA)-encapsulated islet grafts, suggesting a potential shift toward an alternatively-activated M2 macrophage phenotype. To address limited islet availability, the use of (PVPON/TA)-encapsulated differentiated neonatal porcine islets restored euglycemia and maintained β-cell function for more than 200 days after transplantation into diabetic NOD. scid mice, displaying a potential intervention to delay xenotransplant rejection. Our results support the hypothesis that (PVPON/TA) coatings are immunoprotective and may promote islet graft acceptance following transplantation.