Chronic hyperglycemia is toxic to pancreatic -cells, impairing cellular functioning as observed in type 2 diabetes; however, the mechanism underlying -cell dysfunction and the resulting apoptosis via glucose toxicity are not fully characterized. Here, using MIN6N8 cells, a mouse pancreatic -cell line, we show that chronic exposure to high glucose increases cell death mediated by Bax oligomerization, cytochrome C release, and caspase-3 activation. During apoptosis, glucokinase (GCK) expression decreases in high-glucose-treated cells, concomitant with a decrease in cellular ATP production and insulin secretion. Moreover, exposure to a chronically high dose of glucose decreases interactions between GCK and mitochondria with an increase in Bax binding to mitochondria and cytochrome C release. These events are prevented by GCK overexpression, and phosphorylation of proapoptotic Bad proteins in GCK-overexpressing cells is prolonged compared with Neo-transfected cells. Similar results are obtained using primary islet cells. Collectively, these data demonstrate that -cell apoptosis from exposure to chronic high glucose occurs in relation to lowered GCK expression and reduced association with mitochondria. Our results show that this may be one mechanism by which glucose is toxic to -cells and suggests a novel approach to prevent and treat diabetes by manipulating Bax-and GCK-controlled signaling to promote apoptosis or proliferation. Diabetes 54:2602-2611, 2005
Impaired revascularization of transplanted islets is a critical problem that leads to progressive islet loss. Since endothelial progenitor cells (EPCs) are known to aid neovascularization, we aimed to enhance islet engraftment by cotransplanting EPCs with islets. Porcine islets, with (islet-EPC group) or without (islet-only group) human cord blood–derived EPCs, were transplanted into diabetic nude mice. The islet-EPC group reached euglycemia by ∼11 days posttransplantation, whereas the islet-only group did not. Also, the islet-EPC group had a higher serum porcine insulin level than the islet-only group. Islets from the islet-EPC group were more rapidly revascularized at the early period of transplantation without increment of final capillary density at the fully revascularized graft. Enhanced revascularization rate in the islet-EPC group was mainly attributed to stimulating vascular endothelial growth factor-A production from the graft. The rapid revascularization by EPC cotransplantation led to better graft perfusion and recovery from hypoxia. EPC cotransplantation was also associated with greater β-cell proliferation, probably by more basement membrane production and hepatocyte growth factor secretion. In conclusion, cotransplantation of EPCs and islets induces better islet engraftment by enhancing the rate of graft revascularization. These findings might provide a directly applicable tool to enhance the efficacy of islet transplantation in clinical practice.
Although serum bile acid concentrations are approximately 10 mM in healthy subjects, the crosstalk between the biliary system and vascular repair has never been investigated. In this study, tauroursodeoxycholic acid (TUDCA) induced dissociation of CD34 1 hematopoietic stem cells (HSCs) from stromal cells by reducing adhesion molecule expression. TUDCA increased CD341 /Sca1 1 progenitors in mice peripheral blood (PB), and CD34
1, CD31
BackgroundProtein-based Cas9 in vivo gene editing therapeutics have practical limitations owing to their instability and low efficacy. To overcome these obstacles and improve stability, we designed a nanocarrier primarily consisting of lecithin that can efficiently target liver disease and encapsulate complexes of Cas9 with a single-stranded guide RNA (sgRNA) ribonucleoprotein (Cas9-RNP) through polymer fusion self-assembly.ResultsIn this study, we optimized an sgRNA sequence specifically for dipeptidyl peptidase-4 gene (DPP-4) to modulate the function of glucagon-like peptide 1. We then injected our nanocarrier Cas9-RNP complexes directly into type 2 diabetes mellitus (T2DM) db/db mice, which disrupted the expression of DPP-4 gene in T2DM mice with remarkable efficacy. The decline in DPP-4 enzyme activity was also accompanied by normalized blood glucose levels, insulin response, and reduced liver and kidney damage. These outcomes were found to be similar to those of sitagliptin, the current chemical DPP-4 inhibition therapy drug which requires recurrent doses.ConclusionsOur results demonstrate that a nano-liposomal carrier system with therapeutic Cas9-RNP has great potential as a platform to improve genomic editing therapies for human liver diseases.Electronic supplementary materialThe online version of this article (10.1186/s12951-019-0452-8) contains supplementary material, which is available to authorized users.
Peroxisome proliferator-activated receptor (PPAR)-α/γ dual agonists have been developed to treat metabolic diseases; however, most of them exhibit side effects such as body weight gain and oedema. Therefore, we developed a novel PPARα/γ dual agonist that modulates glucose and lipid metabolism without adverse effects. We synthesised novel compounds composed of coumarine and chalcone, determined their crystal structures, and then examined their binding affinity toward PPARα/γ. We investigated the expression of PPARα and PPARγ target genes by chemicals in HepG2, differentiated 3T3-L1, and C2C12 cells. We examined the effect of chemicals on glucose and lipid metabolism in db/db mice. Only MD001 functions as a PPARα/γ dual agonist in vitro. MD001 increased the transcriptional activity of PPARα and PPARγ, resulting in enhanced expression of genes related to β-oxidation and fatty acid and glucose uptake. MD001 significantly improved blood metabolic parameters, including triglycerides, free fatty acids, and glucose, in db/db mice. In addition, MD001 ameliorated hepatic steatosis by stimulating β-oxidation in vitro and in vivo. Our results demonstrated the beneficial effects of the novel compound MD001 on glucose and lipid metabolism as a PPARα/γ dual agonist. Consequently, MD001 may show potential as a novel drug candidate for the treatment of metabolic disorders.
Early graft loss in islet transplantation means that a large amount of donor islets is required. Endothelial cells and endothelial colony-forming cells (ECFCs) have been reported to improve instant blood-mediated inflammatory reaction (IBMIR) in vitro. In this study, we examined if ECFC-coated porcine islets would prevent early graft loss in vivo. Human ECFCs were prepared from cord blood and cocultured with islets to make composite grafts. Diabetic nude mice underwent intraportal transplantation. Blood glucose levels were monitored, and morphological examination of the grafts along with analysis of the components of IBMIR and inflammatory reaction were performed with the liver tissues. The ECFC-coated islets significantly decreased blood glucose levels immediately after transplantation compared to the uncoated islets. Composite ECFC islet grafts were observed in the liver sections, associated with a more insulin(+) area compared to that of the uncoated group within 48 h after transplantation. Deposition of CD41a, C5b-9, and CD11b(+) cells was also decreased in the ECFC-coated group. Expression of porcine HMGB1 and mouse TNF-α was increased in the transplantated groups compared to the sham operation group, with a trend of a decreasing trend across the uncoated group, the ECFC-coated group, and the sham group. We demonstrated that the composite ECFC porcine islets transplanted into the portal vein of nude mice improved early graft loss and IBMIR in vivo.
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