The fate of intracellular S1P regulates lipid droplet turnover and lipotoxicity in pancreatic beta-cells.

Lipotoxicity has been considered the main cause of pancreatic beta-cell failure during type 2 diabetes development. Lipid droplets (LD) are believed to regulate the beta-cell sensitivity to free fatty acids (FFA), but the underlying molecular mechanisms are largely unclear. Accumulating evidence points, however, to an important role of intracellular sphingosine-1-phosphate (S1P) metabolism in lipotoxicity-mediated disturbances of beta-cell function. In the present study, we compared the effects of an increased irreversible S1P degradation (S1P-lyase, SPL overexpression) with those associated with an enhanced S1P recycling (overexpression of S1P phosphatase 1, SGPP1) on LD formation and lipotoxicity in rat INS1E beta-cells. Interestingly, although both approaches led to a reduced S1P concentration, they had opposite effects on the susceptibility to FFA. Overexpression of SGPP1 prevented FFA-mediated caspase-3 activation by a mechanism involving an enhanced lipid storage capacity and prevention of oxidative stress. In contrast, SPL overexpression limited LD biogenesis, content, and size, while accelerating lipophagy. This was associated with FFA-induced hydrogen peroxide formation, mitochondrial fragmentation, and dysfunction, as well as ER stress. These changes coincided with the upregulation of proapoptotic ceramides but were independent of lipid peroxidation rate. Also in human EndoC-ßH1 beta-cells, suppression of SPL with simultaneous overexpression of SGPP1 led to a similar and even more pronounced LD phenotype as that in INS1E-SGPP1 cells. Thus, intracellular S1P turnover significantly regulates LD content and size and influences beta-cell sensitivity to FFA.

Fasting and meal-stimulated serum C-peptide in long-standing type 1 diabetes mellitus.

AIMS: This study aims to evaluate the stability of C-peptide over time and to compare fasting C-peptide and C-peptide response after mixed-meal tolerance test (MMTT) at T90 or T120 with C-peptide area under the curve (AUC) in long-standing type 1 diabetes. METHODS: We included 607 type 1 diabetes individuals with diabetes duration >5 years. C-peptide concentrations (ultrasensitive assay) were collected in the fasting state, and in a subpopulation after MMTT (T0, just prior to, T30-T60-T90-T120, 30-120 min after ingestion of mixed-meal) (n = 168). Fasting C-peptide concentrations (in n = 535) at Year 0 and Year 1 were compared. The clinical determinants associated with residual C-peptide secretion and the correspondence of C-peptide at MMTT T90 / T120 and total AUC were assessed. RESULTS: A total of 153 participants (25%) had detectable fasting serum C-peptide (i.e ≥ 3.8 pmol/L). Fasting C-peptide was significantly lower at Year 1 (p < 0.001, effect size = -0.16). Participants with higher fasting C-peptide had a higher age at diagnosis and shorter disease duration and were less frequently insulin pump users. Overall, 109 of 168 (65%) participants had both non-detectable fasting and post-meal serum C-peptide concentrations. The T90 and T120 C-peptide values at MMTT were concordant with total AUC. In 17 (10%) individuals, C-peptide was only detectable at MMTT and not in the fasting state. CONCLUSIONS: Stimulated C-peptide was detectable in an additional 10% of individuals compared with fasting in individuals with >5 years of diabetes duration. T90 and T120 MMTT measurements showed good concordance with the MMTT total AUC. Overall, there was a decrease of C-peptide at 1-year follow-up.

Impaired pancreatic beta-cell function after a single dose of oral iron: A before-and-after (pre-post) study.

BACKGROUND: Although in vitro and animal studies have shown that iron loading in pancreatic beta cells impairs insulin secretion, no human studies have documented the acute effects of oral iron on beta-cell insulin secretory capacity. In the present study, we determined beta-cell insulin secretory capacity at baseline and after a single oral dose of iron (ferrous sulphate, 120 mg elemental iron) in healthy male individuals. METHODS: Fifteen healthy male volunteers underwent an oral glucose tolerance test (OGTT) to document baseline glucose tolerance and insulin secretion kinetics (baseline OGTT). One week later, the same subjects underwent a second OGTT, 2 h after an oral dose of ferrous sulphate (120 mg of elemental iron) (post-iron OGTT). Changes in disposition index, insulin secretion kinetics, glucose tolerance, insulin resistance, insulin clearance and iron-related parameters in serum were determined. RESULTS: Compared to baseline OGTT, the areas under the curve (AUC) for serum iron and transferrin saturation increased by 125% and 118%, respectively, in the post-iron OGTT. The disposition index decreased by 20% (p = 0.009) and the AUC for glucose concentrations increased by 5.7% (p < 0.001) during the post-iron OGTT. The insulin secretion rate was marginally lower during the first hour (-3.5%, p = 0.63), but became significantly higher during the second hour (22%, p = 0.005) of the post-iron OGTT. Insulin resistance and insulin clearance rate were not affected by iron intake. CONCLUSIONS: The decrease in disposition index and glucose tolerance observed after the oral dose of iron points to an acute iron-induced impairment in pancreatic beta-cell insulin secretory capacity.

From insulin injections to islet transplantation: An overview of the journey.

When, in 1869, Paul Langerhans detected the "islands of tissue" in the pancreas, he took the first step on a journey towards islet transplantation as a treatment for type 1 diabetes. The route has embraced developments across biosciences, surgery, gene therapy and clinical research. This review highlights major milestones along that journey involving whole pancreas transplantation, islet transplantation, the creation of surrogate insulin-secreting cells and novel islet-like structures using genetic and bio-engineering technologies. To obviate the paucity of human tissue, pluripotent stem cells and non-ß-cells within the pancreas have been modified to create physiologically responsive insulin-secreting cells. Before implantation, these can be co-cultured with endothelial cells to promote vascularisation and with immune defence cells such as placental amnion cells to reduce immune rejection. Scaffolds to contain grafts and facilitate surgical placement provide further opportunities to achieve physiological insulin delivery. Alternatively, xenotransplants such as porcine islets might be reconsidered as opportunities exist to circumvent safety concerns and immune rejection. Thus, despite a long and arduous journey, the prospects for increased use of tissue transplantation to provide physiological insulin replacement are drawing ever closer.

Sphingosine-1 Phosphate Lyase Regulates Sensitivity of Pancreatic Beta-Cells to Lipotoxicity.

Elevated levels of free fatty acids (FFAs) have been related to pancreatic beta-cell failure in type 2 diabetes (T2DM), though the underlying mechanisms are not yet fully understood. FFAs have been shown to dysregulate formation of bioactive sphingolipids, such as ceramides and sphingosine-1 phosphate (S1P) in beta-cells. The aim of this study was to analyze the role of sphingosine-1 phosphate lyase (SPL), a key enzyme of the sphingolipid pathway that catalyzes an irreversible degradation of S1P, in the sensitivity of beta-cells to lipotoxicity. To validate the role of SPL in lipotoxicity, we modulated SPL expression in rat INS1E cells and in human EndoC-ßH1 beta-cells. SPL overexpression in INS1E cells (INS1E-SPL), which are characterized by a moderate basal expression level of SPL, resulted in an acceleration of palmitate-mediated cell viability loss, proliferation inhibition and induction of oxidative stress. SPL overexpression affected the mRNA expression of ER stress markers and mitochondrial chaperones. In contrast to control cells, in INS1E-SPL cells no protective effect of oleate was detected. Moreover, Plin2 expression and lipid droplet formation were strongly reduced in OA-treated INS1E-SPL cells. Silencing of SPL in human EndoC-ßH1 beta-cells, which are characterized by a significantly higher SPL expression as compared to rodent beta-cells, resulted in prevention of FFA-mediated caspase-3/7 activation. Our findings indicate that an adequate control of S1P degradation by SPL might be crucially involved in the susceptibility of pancreatic beta-cells to lipotoxicity.

[MicroRNA-328 regulates embryonic stem cells differentiation into insulin-producing cells by targeting TGF-ß2 in vitro].

Objective: To explore the role and its molecular mechanism of miR-328 during the differentiation of embryonic stem cells (ESCs) into insulin-producing cells (IPCs) in vitro. Method: Mouse embryonic stem cell line-mESCs-Nanog-GFP was induced in conditioned medium and divided into negative control group, miR-328 agomir transfected group, miR-328 antagomir transfected group and transforming growth factor ß2 (TGF-ß2) siRNA transfected group. The function of IPCs was identified by real-time quantitative PCR (qPCR) detecting system and immunofluorescence in above-mentioned groups. Methods of qPCR, immunofluorescence and enzyme-linked immunosorbent assay (ELISA) were used to detect effects of overexpression and inhibition of miR-328 on differentiation of multilineage precursor cells. We predicted the binding sites of miR-328 and TGF-ß2 by performing the bioinformatics analysis. Dual luciferase reporter gene and Western blotting were employed to identify the regulatory relationship between miR-328 and TGF-ß2. Results: mESCs could be transfected with miR-328 agomir, with an efficacy of 70%-80%. Up-regulated miR-328 in MPCs reduced the RNA expression of several key transcription factors which were crucial for early pancreatic development. Additionally, the insulin released by IPCs decreased in response to glucose stimulation (all P<0.05). However, overexpression of miR-328 led to the decrease of protein level of insulin and Nkx6.1 (all P<0.05). Transfection of miR-328 antagomir had the opposite effects (P<0.05). The dual luciferase reporter gene assay revealed that miR-328 functioned via binding to the 3' non-coding region (3'-UTR) of the TGF-ß2. Western blotting indicated that miR-328 regulated protein expression. After knockdown of miR-328, the relative expression of TGF-ß2 was 1.00±0.01. After co-transfection of miR-328 antagomir and TGF-ß2 siRNA, the relative expression of TGF-ß2 was 0.80±0.03. After downregulating TGF-ß2, the relative expression of TGF-ß2 was 0.20±0.01. Knockdown of TGF-ß2 down-regulated the expression of early pancreatic transcription factors (P<0.05) and inhibited Pdx1(+)cell differentiation. Conclusion: miR-328 can inhibit the differentiation of ESCs into IPCs via binding to 3' UTR of TGF-ß2, and provide a new regulatory pathway for the treatment of diabetes with stem cells.

[Glucose metabolism in older patients]. / Glukosestoffwechsel im fortgeschrittenen Lebensalter.

Current guidelines for specialized treatment of diabetes mellitus in the elderly (>65 years old) are primarily based on epidemiologic studies and geriatric assessment of functional health. Yet, age-dependent alterations of glucose metabolism and homeostasis are highly relevant to the pathophysiology of diabetes in the elderly. In this review, we focus on age-related alterations in metabolic pathways and their relevance for the specialized diabetic care in the elderly. We review the role of increasing insulin resistance, age-related ß­cell dysfunction and incretin secretion. The clinical relevance of these effects will also be discussed in regard to the central geriatric syndrome of sarcopenia and antidiabetic drug therapy.

Meta-genome-wide association studies identify a locus on chromosome 1 and multiple variants in the MHC region for serum C-peptide in type 1 diabetes.

AIMS/HYPOTHESIS: The aim of this study was to identify genetic variants associated with beta cell function in type 1 diabetes, as measured by serum C-peptide levels, through meta-genome-wide association studies (meta-GWAS). METHODS: We performed a meta-GWAS to combine the results from five studies in type 1 diabetes with cross-sectionally measured stimulated, fasting or random C-peptide levels, including 3479 European participants. The p values across studies were combined, taking into account sample size and direction of effect. We also performed separate meta-GWAS for stimulated (n = 1303), fasting (n = 2019) and random (n = 1497) C-peptide levels. RESULTS: In the meta-GWAS for stimulated/fasting/random C-peptide levels, a SNP on chromosome 1, rs559047 (Chr1:238753916, T>A, minor allele frequency [MAF] 0.24-0.26), was associated with C-peptide (p = 4.13 × 10-8), meeting the genome-wide significance threshold (p < 5 × 10-8). In the same meta-GWAS, a locus in the MHC region (rs9260151) was close to the genome-wide significance threshold (Chr6:29911030, C>T, MAF 0.07-0.10, p = 8.43 × 10-8). In the stimulated C-peptide meta-GWAS, rs61211515 (Chr6:30100975, T/-, MAF 0.17-0.19) in the MHC region was associated with stimulated C-peptide (ß [SE] = - 0.39 [0.07], p = 9.72 × 10-8). rs61211515 was also associated with the rate of stimulated C-peptide decline over time in a subset of individuals (n = 258) with annual repeated measures for up to 6 years (p = 0.02). In the meta-GWAS of random C-peptide, another MHC region, SNP rs3135002 (Chr6:32668439, C>A, MAF 0.02-0.06), was associated with C-peptide (p = 3.49 × 10-8). Conditional analyses suggested that the three identified variants in the MHC region were independent of each other. rs9260151 and rs3135002 have been associated with type 1 diabetes, whereas rs559047 and rs61211515 have not been associated with a risk of developing type 1 diabetes. CONCLUSIONS/INTERPRETATION: We identified a locus on chromosome 1 and multiple variants in the MHC region, at least some of which were distinct from type 1 diabetes risk loci, that were associated with C-peptide, suggesting partly non-overlapping mechanisms for the development and progression of type 1 diabetes. These associations need to be validated in independent populations. Further investigations could provide insights into mechanisms of beta cell loss and opportunities to preserve beta cell function.

Overexpression of sphingosine-1-phosphate lyase protects insulin-secreting cells against cytokine toxicity.

Increasing evidence suggests a crucial role of inflammation in cytokine-mediated ß-cell dysfunction and death in type 1 diabetes mellitus, although the mechanisms are incompletely understood. Sphingosine 1-phosphate (S1P) is a multifunctional bioactive sphingolipid involved in the development of many autoimmune and inflammatory diseases. Here, we investigated the role of intracellular S1P in insulin-secreting INS1E cells by genetically manipulating the S1P-metabolizing enzyme S1P lyase (SPL). The expression of spl was down-regulated by cytokines in INS1E cells and rat islets. Overexpression of SPL protected against cytokine toxicity. Interestingly, the SPL overexpression did not suppress the cytokine-induced NFκB-iNOS-NO pathway but attenuated calcium leakage from endoplasmic reticulum (ER) stores as manifested by lower cytosolic calcium levels, higher expression of the ER protein Sec61a, decreased dephosphorylation of Bcl-2-associated death promoter (Bad) protein, and weaker caspase-3 activation in cytokine-treated (IL-1ß, TNFα, and IFNγ) cells. This coincided with reduced cytokine-mediated ER stress, indicated by measurements of CCAAT/enhancer-binding protein homologous protein (chop) and immunoglobulin heavy chain binding protein (bip) levels. Moreover, cytokine-treated SPL-overexpressing cells exhibited increased expression of prohibitin 2 (Phb2), involved in the regulation of mitochondrial assembly and respiration. SPL-overexpressing cells were partially protected against cytokine-mediated ATP reduction and inhibition of glucose-induced insulin secretion. siRNA-mediated spl suppression resulted in effects opposite to those observed for SPL overexpression. Knockdown of phb2 partially reversed beneficial effects of SPL overexpression. In conclusion, the relatively low endogenous Spl expression level in insulin-secreting cells contributes to their extraordinary vulnerability to proinflammatory cytokine toxicity and may therefore represent a promising target for ß-cell protection in type 1 diabetes mellitus.

Patients With Long-QT Syndrome Caused by Impaired hERG-Encoded Kv11.1 Potassium Channel Have Exaggerated Endocrine Pancreatic and Incretin Function Associated With Reactive Hypoglycemia.

BACKGROUND: Loss-of-function mutations in hERG (encoding the Kv11.1 voltage-gated potassium channel) cause long-QT syndrome type 2 (LQT2) because of prolonged cardiac repolarization. However, Kv11.1 is also present in pancreatic α and ß cells and intestinal L and K cells, secreting glucagon, insulin, and the incretins glucagon-like peptide-1 (GLP-1) and GIP (glucose-dependent insulinotropic polypeptide), respectively. These hormones are crucial for glucose regulation, and long-QT syndrome may cause disturbed glucose regulation. We measured secretion of these hormones and cardiac repolarization in response to glucose ingestion in LQT2 patients with functional mutations in hERG and matched healthy participants, testing the hypothesis that LQT2 patients have increased incretin and ß-cell function and decreased α-cell function, and thus lower glucose levels. METHODS: Eleven patients with LQT2 and 22 sex-, age-, and body mass index-matched control participants underwent a 6-hour 75-g oral glucose tolerance test with ECG recording and blood sampling for measurements of glucose, insulin, C-peptide, glucagon, GLP-1, and GIP. RESULTS: In comparison with matched control participants, LQT2 patients had 56% to 78% increased serum insulin, serum C-peptide, plasma GLP-1, and plasma GIP responses (P=0.03-0.001) and decreased plasma glucose levels after glucose ingestion (P=0.02) with more symptoms of hypoglycemia (P=0.04). Sixty-three percent of LQT2 patients developed hypoglycemic plasma glucose levels (<70 mg/dL) versus 36% control participants (P=0.16), and 18% patients developed serious hypoglycemia (<50 mg/dL) versus none of the controls. LQT2 patients had defective glucagon responses to low glucose, P=0.008. ß-Cell function (Insulin Secretion Sensitivity Index-2) was 2-fold higher in LQT2 patients than in controls (4398 [95% confidence interval, 2259-8562] versus 2156 [1961-3201], P=0.03). Pharmacological Kv11.1 blockade (dofetilide) in rats had similar effect, and small interfering RNA inhibition of hERG in ß and L cells increased insulin and GLP-1 secretion up to 50%. Glucose ingestion caused cardiac repolarization disturbances with increased QTc intervals in both patients and controls, but with a 122% greater increase in QTcF interval in LQT2 patients (P=0.004). CONCLUSIONS: Besides a prolonged cardiac repolarization phase, LQT2 patients display increased GLP-1, GIP, and insulin secretion and defective glucagon secretion, causing decreased plasma glucose and thus increased risk of hypoglycemia. Furthermore, glucose ingestion increased QT interval and aggravated the cardiac repolarization disturbances in LQT2 patients. CLINICAL TRIAL REGISTRATION: URL: http://clinicaltrials.gov. Unique identifier: NCT02775513.

Factors contributing to partial remission in type 1 diabetes: analysis based on the insulin dose-adjusted HbA1c in 3657 children and adolescents from Germany and Austria.

OBJECTIVE: Insulin dose-adjusted hemoglobin A1c (HbA1C, IDAA1c) correlates well with stimulated C-peptide levels, but has not yet been evaluated in a large cohort of patients with Type 1 diabetes (T1D). METHODS: We investigated prevalence of partial remission (PREM) defined by IDAA1c ≤9 in 3657 in children with new-onset T1D who were continuously followed over 6 years. We evaluated the predictors of PREM using the multicenter database from the DPV (Diabetes Patienten Verlaufsdokumentation) registry. RESULTS: PREM occurred in 71% of patients. Median duration was 9 (0-21) months. Compared to children <5 years at T1D onset, those aged 5-10 and ≥10 years had twice the chance of developing PREM (OR: 2.08, CI: 1.67-2.60; P < .001 and OR: 2.16, CI: 1.70-2.75; P < .001). Boys were more likely to develop PREM than girls (OR 1.41, CI: 1.18-1.69; P = .0002). Further predictors for PREM were: ketoacidosis, autoantibodies, and HbA1c at T1D onset. These results were confirmed by quantile regression analysis with duration of PREM as dependent variable. CONCLUSION: This research on a large cohort provides insight into epidemiologic characteristics of PREM in T1D defined by IDAA1c. As IDAA1c does not discriminate between insulin sensitivity and secretion, available data cannot resolve whether the sex-difference in PREM reflects innate higher insulin resistance in girls, or better beta-cell recovery in boys. Further research is needed to clarify the usefulness and performance of IDAA1c in clinical practice.

Umbilical cord mesenchymal stem cells are able to undergo differentiation into functional islet-like cells in type 2 diabetic tree shrews.

Islet transplantation is arguably one of the most promising strategies to treat patients suffering with diabetes mellitus. However, a combination of a lack of donors and chronic immune rejection limit clinical applications. Here, we evaluated the efficacy of cell therapy using islet-like cells differentiated from umbilical cord mesenchymal stem cells (UC-MSCs) of tree shrews for the treatment of type 2 diabetes. Enhanced green fluorescent protein (eGFP) labeled UC-MSCs were directly injected into type 2 diabetic tree shrews, where UC-MSC differentiated into functional islet-like cells and alleviated disease severity, as evidenced by improved biochemical features and reduced concentrations of inflammatory cytokines. We also demonstrated that in vitro culture of UC-MSCs for six days in a high-glucose environment (40 mmol/L or 60 mmol/L glucose) resulted in significant gene methylation. The potency of UC-MSCs differentiated into insulin-secreting cells was attributed to the activation of Notch signal pathways. This study provides evidence that cell therapy of islet-like cells differentiated from UC-MSCs is a feasible, simple and inexpensive approach in the treatment of type 2 diabetes.

Homeostatic model assessment of beta cell function predicting abnormal oral glucose tolerance testing in pregnancy: a systematic review and meta-analysis.

BACKGROUND: Gestational diabetes mellitus (GDM) complicates 1-14% of pregnancies and relates to increased risk of adverse obstetric outcomes. Currently GDM is diagnosed using an oral glucose tolerance test (OGTT), which is burdensome and time intensive. OBJECTIVE: To compare current literature on whether the homeostatic model assessment beta cell function (HOMA-ß) is an accurate predictor of an abnormal OGTT in pregnant women. METHODS: Pubmed, Cochrane and Embase were searched. Included studies evaluated pregnant women at risk for GDM using the homeostatic model assessment of beta cell function (HOMA-ß) for the assessment of beta cell function and the OGTT. Studies with animals, non-pregnant women, women with type 2 diabetes and post-partum diabetes were excluded. The QUADAS-2 criteria were used to assess the methodological quality of studies. RESULTS: A total of 12 studies were included, reporting on 7292 women. Seven studies showed a difference in beta cell function between women with impaired glucose tolerance compared to healthy pregnant women. HOMA-ß is significantly lower in impaired glucose tolerance (p < 0.001). CONCLUSIONS: Although HOMA-ß is lower in women with abnormal OGTT in pregnancy, given the high degree of heterogeneity of studies, we do not propagate HOMA-ß as a sole diagnostic tool replacing OGTT to diagnose GDM.

Stem cell therapy emerging as the key player in treating type 1 diabetes mellitus.

Type 1 diabetes mellitus (T1DM) is an autoimmune disease causing progressive destruction of pancreatic ß cells, ultimately resulting in loss of insulin secretion producing hyperglycemia usually affecting children. Replacement of damaged ß cells by cell therapy can treat it. Currently available strategies are insulin replacement and islet/pancreas transplantation. Unfortunately these offer rescue for variable duration due to development of autoantibodies. For pancreas/islet transplantation a deceased donor is required and various shortfalls of treatment include quantum, cumbersome technique, immune rejection and limited availability of donors. Stem cell therapy with assistance of cellular reprogramming and ß-cell regeneration can open up new therapeutic modalities. The present review describes the history and current knowledge of T1DM, evolution of cell therapies and different cellular therapies to cure this condition.

Medication-induced diabetes mellitus.

Epidemiological studies and case reports have demonstrated an increased rate of development of diabetes mellitus consequent to taking diverse types of medication. This review explores this evidence linking these medications and development of diabetes and presents postulated mechanisms by which the medications might cause diabetes. Some medications are associated with a reduction in insulin production, some with reduction in insulin sensitivity, and some appear to be associated with both reduction in insulin production and insulin sensitivity.

Insulin-secreting adipose-derived mesenchymal stromal cells with bone marrow-derived hematopoietic stem cells from autologous and allogenic sources for type 1 diabetes mellitus.

BACKGROUND AIMS: Stem cell therapy (SCT) is now the up-coming therapeutic modality for treatment of type 1 diabetes mellitus (T1DM). METHODS: Our study was a prospective, open-labeled, two-armed trial for 10 T1DM patients in each arm of allogenic and autologous adipose-derived insulin-secreting mesenchymal stromal cells (IS-AD-MSC)+bone marrow-derived hematopoietic stem cell (BM-HSC) infusion. Group 1 received autologous SCT: nine male patients and one female patient; mean age, 20.2 years, disease duration 8.1 years; group 2 received allogenic SCT: six male patients and four female patients, mean age, 19.7 years and disease duration, 7.9 years. Glycosylated hemoglobin (HbA1c) was 10.99%; serum (S.) C-peptide, 0.22 ng/mL and insulin requirement, 63.9 IU/day in group 1; HbA1c was 11.93%, S.C-peptide, 0.028 ng/mL and insulin requirement, 57.55 IU/day in group 2. SCs were infused into the portal+thymic circulation and subcutaneous tissue under non-myelo-ablative conditioning. Patients were monitored for blood sugar, S.C-peptide, glutamic acid decarboxylase antibodies and HbA1c at 3-month intervals. RESULTS: Group 1 received mean SCs 103.14 mL with 2.65 ± 0.8 × 10(4) ISCs/kg body wt, CD34+ 0.81% and CD45-/90+/73+, 81.55%. Group 2 received mean SCs 95.33 mL with 2.07 ± 0.67 × 10(4) ISCs/kg body wt, CD34+ 0.32% and CD45-/90+/73+ 54.04%. No untoward effect was observed with sustained improvement in HbA1c and S.C-peptide in both groups with a decrease in glutamic acid decarboxylase antibodies and reduction in mean insulin requirement. CONCLUSIONS: SCT is a safe and viable treatment option for T1DM. Autologous IS-AD-MSC+ BM-HSC co-infusion offers better long-term control of hyperglycemia as compared with allogenic SCT.

Transplantation of insulin-secreting cells differentiated from human adipose tissue-derived stem cells into type 2 diabetes mice.

Currently, there are limited ways to preserve or recover insulin secretory capacity in human pancreas. We evaluated the efficacy of cell therapy using insulin-secreting cells differentiated from human eyelid adipose tissue-derived stem cells (hEAs) into type 2 diabetes mice. After differentiating hEAs into insulin-secreting cells (hEA-ISCs) in vitro, cells were transplanted into a type 2 diabetes mouse model. Serum levels of glucose, insulin and c-peptide were measured, and changes of metabolism and inflammation were assessed in mice that received undifferentiated hEAs (UDC group), differentiated hEA-ISCs (DC group), or sham operation (sham group). Human gene expression and immunohistochemical analysis were done. DC group mice showed improved glucose level, and survival up to 60 days compared to those of UDC and sham group. Significantly increased levels of human insulin and c-peptide were detected in sera of DC mice. RT-PCR and immunohistochemical analysis showed human gene expression and the presence of human cells in kidneys of DC mice. When compared to sham mice, DC mice exhibited lower levels of IL-6, triglyceride and free fatty acids as the control mice. Transplantation of hEA-ISCs lowered blood glucose level in type 2 diabetes mice by increasing circulating insulin level, and ameliorating metabolic parameters including IL-6.

In Vivo Differentiation of Endogenous Bone Marrow-Derived Cells into Insulin-Producing Cells Using Four Soluble Factors.

Four soluble factors-putrescine, glucosamine, nicotinamide, and signal transducer and activator of transcription 3 (STAT3) inhibitor BP-1-102-were shown to differentiate bone marrow mononucleated cells (BMNCs) into functional insulin-producing cells (IPCs) in vitro. Transplantation of these IPCs improved hyperglycemia in diabetic mice. However, the role of endogenous BMNC regeneration in this effect was unclear. This study aimed to evaluate the effect of these factors on in vivo BMNC differentiation into IPCs in diabetic mice. Mice were orally administered the factors for 5 days, twice at 2-week intervals, and monitored for 45-55 days. Glucose tolerance, glucose-stimulated insulin secretion, and pancreatic insulin content were measured. Chimeric mice harboring BMNCs from insulin promoter luciferase/green fluorescent protein (GFP) transgenic mice were used to track endogenous BMNC fate. These factors lowered blood glucose levels, improved glucose tolerance, and enhanced insulin secretion. Immunostaining confirmed IPCs in the pancreas, showing the potential of these factors to induce ß-cell regeneration and improve diabetes treatment.

Docosahexanoic Acid Attenuates Palmitate-Induced Apoptosis by Autophagy Upregulation via GPR120/mTOR Axis in Insulin-Secreting Cells.

BACKGRUOUND: Polyunsaturated fatty acids (PUFAs) reportedly have protective effects on pancreatic ß-cells; however, the underlying mechanisms are unknown. METHODS: To investigate the cellular mechanism of PUFA-induced cell protection, mouse insulinoma 6 (MIN6) cells were cultured with palmitic acid (PA) and/or docosahexaenoic acid (DHA), and alterations in cellular signaling and apoptosis were examined. RESULTS: DHA treatment remarkably repressed caspase-3 cleavage and terminal deoxynucleotidyl transferase-mediated UTP nick end labeling (TUNEL)-positive red dot signals in PA-treated MIN6 cells, with upregulation of autophagy, an increase in microtubule- associated protein 1-light chain 3 (LC3)-II, autophagy-related 5 (Atg5), and decreased p62. Upstream factors involved in autophagy regulation (Beclin-1, unc51 like autophagy activating kinase 1 [ULK1], phosphorylated mammalian target of rapamycin [mTOR], and protein kinase B) were also altered by DHA treatment. DHA specifically induced phosphorylation on S2448 in mTOR; however, phosphorylation on S2481 decreased. The role of G protein-coupled receptor 120 (GPR120) in the effect of DHA was demonstrated using a GPR120 agonist and antagonist. Additional treatment with AH7614, a GPR120 antagonist, significantly attenuated DHA-induced autophagy and protection. Taken together, DHA-induced autophagy activation with protection against PA-induced apoptosis mediated by the GPR120/mTOR axis. CONCLUSION: These findings indicate that DHA has therapeutic effects on PA-induced pancreatic ß-cells, and that the cellular mechanism of ß-cell protection by DHA may be a new research target with potential pharmacotherapeutic implications in ß-cell protection.

Protector Role of Cx30.2 in Pancreatic ß-Cell against Glucotoxicity-Induced Apoptosis.

Glucotoxicity may exert its deleterious effects on pancreatic ß-cell function via a myriad of mechanisms, leading to impaired insulin secretion and, eventually, type 2 diabetes. ß-cell communication requires gap junction channels to be present among these cells. Gap junctions are constituted by transmembrane proteins of the connexins (Cxs) family. Two Cx genes have been identified in ß cells, Cx36 and Cx30.2. We have found evidence that the glucose concentration on its own is sufficient to regulate Cx30.2 gene expression in mouse islets. In this work, we examine the involvement of the Cx30.2 protein in the survival of ß cells (RIN-m5F). METHODS: RIN-m5F cells were cultured in 5 mM D-glucose (normal) or 30 mM D-glucose (high glucose) for 24 h. Cx30.2 siRNAs was used to downregulate Cx30.2 expression. Apoptosis was measured by means of TUNEL, an annexin V staining method, and the cleaved form of the caspase-3 protein was determined using Western blot. RESULTS: High glucose did not induce apoptosis in RIN-m5F ß cells after 24 h; interestingly, high glucose increased the Cx30.2 total protein levels. Moreover, this work found that the downregulation of Cx30.2 expression in high glucose promoted apoptosis in RIN-m5F cells. CONCLUSION: The data suggest that the upregulation of Cx30.2 protects ß cells from hyperglycemia-induced apoptosis. Furthermore, Cx30.2 may be a promising avenue of therapeutic investigation for the treatment of glucose metabolic disorders.