| 1. |
- Balboa, Diego, et al.
(författare)
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Functional, metabolic and transcriptional maturation of human pancreatic islets derived from stem cells.
- 2022
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Ingår i: Nature Biotechnology. - : Springer Nature. - 1087-0156 .- 1546-1696. ; 40:7, s. 1042-1055
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Tidskriftsartikel (refereegranskat)abstract
- Transplantation of pancreatic islet cells derived from human pluripotent stem cells is a promising treatment for diabetes. Despite progress in the generation of stem-cell-derived islets (SC-islets), no detailed characterization of their functional properties has been conducted. Here, we generated functionally mature SC-islets using an optimized protocol and benchmarked them comprehensively against primary adult islets. Biphasic glucose-stimulated insulin secretion developed during in vitro maturation, associated with cytoarchitectural reorganization and the increasing presence of alpha cells. Electrophysiology, signaling and exocytosis of SC-islets were similar to those of adult islets. Glucose-responsive insulin secretion was achieved despite differences in glycolytic and mitochondrial glucose metabolism. Single-cell transcriptomics of SC-islets in vitro and throughout 6 months of engraftment in mice revealed a continuous maturation trajectory culminating in a transcriptional landscape closely resembling that of primary islets. Our thorough evaluation of SC-islet maturation highlights their advanced degree of functionality and supports their use in further efforts to understand and combat diabetes.
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| 2. |
- Carlsson, Per-Ola
(författare)
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Microcirculation in native and transplanted rodent pancreatic islets with special reference to the influence of diabetes mellitus
- 1998
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- The aim of the present work was to characterize the islet microcirculation in animal models of type 1 and type 2 diabetes, as well as in islets transplanted to diabetic or normoglycemic recipients. For this purpose, a microsphere technique was evaluated and applied for measurements of islet blood flow in mice.Furthermore, micropuncture techniques for measurements of hydrostatic pressure and tissue oxygen tensionwere adapted to native and transplanted islets. Islet blood flow in normal mice was 1.5-2.5 µl x min-1 x mg estimated islet weight-1. The capillary pressure in native pancreatic islets of rats was ≈3 mm Hg. Obese-hyperglycemic mice demonstrated an jncreased islet blood perfusion, presumably due to leptin-deficiency at 1 month of age, and a decreased islet blood perfusion induced by persistent hyperglycemia at 6-7 months of age, when compared with age-matched lean mice. GK rats, another animal model of type 2 diabetes, displayed a hyperglycemia-dependent increased islet blood flow and islet capillary pressureat ≈15 weeks of age. The present findings suggest that disturbances in islet microcirculation may contribute to the decline in β-cell function seen in type 2 diabetes. An increased islet blood perfusion was also seen in the prediabetic phase in female NOD mice, an animal model of type 1 diabetes. This increase was probably due to an excessive production of nitric oxide. The increased islet blood flow may augment homing of inflammatory cells and soluble factors involved in β-cell destruction to the pancreatic islets during the development of type 1 diabetes in this animal model. The capillary pressure in syngeneic rat islets implanted beneath the kidney capsule approached that of capillaries in the kidney, i.e. 3-4 times higher than in native islets. In diabetic recipients, the graft capillary pressure was higher than in control animals, and was associated with an increased blood flow, as measured by a combination of microspheres and an ultrasonic flow probe. This increase in graft blood flow was not seen when using the laser-Doppler technique. With both techniques the blood perfusion of the grafts was markedly lower than that of the adjacent kidney cortex or native pancreatic islets. The grafts, especially in diabetic recipients, also demonstrated a markedly lower tissue oxygen tension after revascularization than native islets. The latter results are suggestive of an insufficient and inadequate engraftment of transplanted pancreatic islets. This may be of importance for the failures of islet grafts to cure diabetes.
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| 3. |
- Christoffersson, Gustaf, et al.
(författare)
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Intramuscular islet transplantation promotes restored islet vascularity
- 2011
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Ingår i: Islets. - : Informa UK Limited. - 1938-2014 .- 1938-2022. ; 3:2, s. 69-71
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- In a recent publication, we reported that islets transplanted to mouse striated muscle became revascularized with intra-islet vessel densities comparable to native islets. Revascularization of islet grafts was completely dependent on recruited Gr-1+ leukocytes. Diabetic mice cured by transplantation of 300 islets into muscle handled glucose tolerance tests as healthy controls, whereas mice cured by intraportal islet transplantation into the liver had increased blood glucose values during the load. The translational impact of these observations were confirmed by magnetic resonance imaging of autotransplanted islets in the forearm muscle of pancreactomized patients, and higher blood perfusion of the grafts compared to adjacent muscle were found. In summary, the striated muscle is a promising site for islet transplantation which promotes full revascularization of implanted grafts. The proangiogenic role of recruited leukocytes during engraftment needs to be further characterized, and considered for immune suppression treatments.
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| 4. |
- Cunha, Daniel A., et al.
(författare)
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Thrombospondin 1 protects pancreatic beta-cells from lipotoxicity via the PERK-NRF2 pathway
- 2016
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Ingår i: Cell Death and Differentiation. - : Springer Science and Business Media LLC. - 1350-9047 .- 1476-5403. ; 23:12, s. 1995-2006
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Tidskriftsartikel (refereegranskat)abstract
- The failure of beta-cells has a central role in the pathogenesis of type 2 diabetes, and the identification of novel approaches to improve functional beta-cell mass is essential to prevent/revert the disease. Here we show a critical novel role for thrombospondin 1 (THBS1) in beta-cell survival during lipotoxic stress in rat, mouse and human models. THBS1 acts from within the endoplasmic reticulum to activate PERK and NRF2 and induce a protective antioxidant defense response against palmitate. Prolonged palmitate exposure causes THBS1 degradation, oxidative stress, activation of JNK and upregulation of PUMA, culminating in beta-cell death. These findings shed light on the mechanisms leading to beta-cell failure during metabolic stress and point to THBS1 as an interesting therapeutic target to prevent oxidative stress in type 2 diabetes.
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| 5. |
- Davies, Lindsay C., et al.
(författare)
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Type 1 Diabetes Mellitus Donor Mesenchymal. Stromal Cells Exhibit Comparable Potency to Healthy Controls In Vitro
- 2016
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Ingår i: Stem Cells Translational Medicine. - : Oxford University Press (OUP). - 2157-6564 .- 2157-6580. ; 5:11, s. 1485-1495
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Tidskriftsartikel (refereegranskat)abstract
- Bone marrow mesenchymal stromal cells (BM-MSCs) have been characterized and used in many clinical studies based on their immunomodulatory and regenerative properties. We have recently reported the benefit of autologous MSC systemic therapy in the treatment of type 1 diabetes mellitus (T1D). Compared with allogeneic cells, use of autologous products reduces the risk of eliciting undesired complications in the recipient, including rejection, immunization, and transmission of viruses and prions; however, comparable potency of autologous cells is required for this treatment approach to remain feasible. To date, no analysis has been reported that phenotypically and functionally characterizes MSCs derived from newly diagnosed and late-stage T1D donors in vitro with respect to their suitability for systemic immunotherapy. In this study, we used gene array in combination with functional in vitro assays to address these questions. MSCs from T1D donors and healthy controls were expanded from BM aspirates. BM mononuclear cell counts and growth kinetics were comparable between the groups, with equivalent colony-forming unit-fibroblast capacity. Gene microarrays demonstrated differential gene expression between healthy and late-stage T1D donors in relation to cytokine secretion, immunomodulatory activity, and wound healing potential. Despite transcriptional differences, T1D MSCs did not demonstrate a significant difference from healthy controls in immunosuppressive activity, migratory capacity, or hemocompatibility. We conclude that despite differential gene expression, expanded MSCs from T1D donors are phenotypically and functionally similar to healthy control MSCs with regard to their immunomodulatory and migratory potential, indicating their suitability for use in autologous systemic therapy.
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| 6. |
- Elksnis, Andris, 1993-
(författare)
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Pharmaceutical Protection of Beta-Cells in Diabetes : Using Tyrosine Kinase Inhibition and NOX4 Inhibitors
- 2022
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Diabetes mellitus is a complex and heterogenous disease, with loss of beta-cell function and mass being a characteristic of not only type 1 diabetes (T1D), but also type 2 diabetes (T2D). In T1D, inappropriate inflammatory signaling is thought to participate in the autoimmune suppression and destruction of beta-cells. In T2D progressive insulin resistance with resulting glucolipotoxicity, increased inflammation and oxidative stress, drives islet amyloid formation and subsequent beta-cell exhaustion and failure. Even under best managed care, disease progression and eventual complications are unavoidable. New interventions that aim to improve beta-cell survival are highly needed. This thesis investigates two such possible interventions: the tyrosine kinase inhibitor Imatinib, and selective NADPH-oxidase inhibition.Imatinib mesylate, used in treatment of chronic myeloid leukemia and other malignancies, was soon after its introduction reported to possess anti-diabetic properties in both T1D and T2D patients undergoing treatment. Imatinib has been shown to prevent and reverse diabetes in NOD mice and improve glucose tolerance in high fat diet treated rats. In paper I, we aimed to characterize the mechanisms by which imatinib protects beta-cells. We found that imatinib inhibits complex I and II of the respiratory chain, leading to improved beta-cell survival through AMPK activation, reduced amyloid formation and protection against TXNIP upregulation.Oxidative stress may play a pivotal role in the development of beta-cell dysfunction and failure in T2D. The NADPH-oxidases are a family of 7 enzymes (NOX1-5 and DUOX 1-2), that produce reactive oxygen species that are important in various physiological processes but may, if excessively activated, also be a source for oxidative stress in T2D. In paper II, we evaluate novel selective NOX inhibitors as protective agents against in vitro induced human beta-cell stress. Selective NOX4 inhibition protected beta-cells against both cytokines and high-glucose + palmitate. In paper III we found that NOX4 inhibition increased mitochondrial membrane potential, mitochondrial reactive oxygen species and ATP/ADP ratio in a human beta-cell line, and this was paralleled with protection against human islet cell death when challenged with high-glucose and palmitate. Finally, in paper IV, we attempt to apply these findings in vivo, by transplanting athymic diabetic mice with human islets and treating them with a NOX4 inhibitor over a period of 4 weeks. Treated mice achieved lower blood glucose levels and water consumption throughout the treatment period, and apoptotic rates of insulin-positive human cells, measured as co-localization of insulin and cleaved caspase-3, were greatly reduced.
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| 7. |
- Elksnis, Andris, et al.
(författare)
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Pharmacological Inhibition of NOX4 Improves Mitochondrial Function and Survival in Human Beta-Cells
- 2021
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Ingår i: Biomedicines. - : MDPI. - 2227-9059. ; 9:12
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Tidskriftsartikel (refereegranskat)abstract
- Previous studies have reported beneficial effects of NADPH oxidase 4 (NOX4) inhibition on beta-cell survival in vitro and in vivo. The mechanisms by which NOX4 inhibition protects insulin producing cells are, however, not known. The aim of the present study was to investigate the effects of a pharmacological NOX4 inhibitor (GLX7013114) on human islet and EndoC-beta H1 cell mitochondrial function, and to correlate such effects with survival in islets of different size, activity, and glucose-stimulated insulin release responsiveness. We found that maximal oxygen consumption rates, but not the rates of acidification and proton leak, were increased in islets after acute NOX4 inhibition. In EndoC-beta H1 cells, NOX4 inhibition increased the mitochondrial membrane potential, as estimated by JC-1 fluorescence; mitochondrial reactive oxygen species (ROS) production, as estimated by MitoSOX fluorescence; and the ATP/ADP ratio, as assessed by a bioluminescent assay. Moreover, the insulin release from EndoC-beta H1 cells at a high glucose concentration increased with NOX4 inhibition. These findings were paralleled by NOX4 inhibition-induced protection against human islet cell death when challenged with high glucose and sodium palmitate. The NOX4 inhibitor protected equally well islets of different size, activity, and glucose responsiveness. We conclude that pharmacological alleviation of NOX4-induced inhibition of beta-cell mitochondria leads to increased, and not decreased, mitochondrial ROS, and this was associated with protection against cell death occurring in different types of heterogeneous islets. Thus, NOX4 inhibition or modulation may be a therapeutic strategy in type 2 diabetes that targets all types of islets.
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| 8. |
- Elksnis, Andris, et al.
(författare)
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The selective NOX4 inhibitor GLX7013159 decreases blood glucose concentrations and human beta-cell apoptotic rates in diabetic NMRI nu/nu mice transplanted with human islets
- 2023
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Ingår i: Free radical research. - : Taylor & Francis. - 1071-5762 .- 1029-2470. ; 57:6-12, s. 460-469
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Tidskriftsartikel (refereegranskat)abstract
- NADPH oxidase 4 (NOX4) inhibition has been reported to mitigate diabetes-induced beta-cell dysfunction and improve survival in vitro, as well as counteract high-fat diet-induced glucose intolerance in mice. We investigated the antidiabetic effects of the selective NOX4 inhibitor GLX7013159 in vivo in athymic diabetic mice transplanted with human islets over a period of 4 weeks. The GLX7013159-treated mice achieved lower blood glucose and water consumption throughout the treatment period. Furthermore, GLX7013159 treatment resulted in improved insulin and c-peptide levels, better insulin secretion capacity, as well as in greatly reduced apoptotic rates of the insulin-positive human cells, measured as colocalization of insulin and cleaved caspase-3. We conclude that the antidiabetic effects of NOX4 inhibition by GLX7013159 are observed also during a prolonged study period in vivo and are likely to be due to an improved survival and function of the human beta-cells.
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| 9. |
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| 10. |
- Espes, Daniel, et al.
(författare)
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Cotransplantation of Polymerized Hemoglobin Reduces β-Cell Hypoxia and Improves β-Cell Function in Intramuscular Islet Grafts
- 2015
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Ingår i: Transplantation. - 0041-1337 .- 1534-6080. ; 99:10, s. 2077-2082
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Tidskriftsartikel (refereegranskat)abstract
- Background. Muscle is a promising alternative site for islet transplantation that facilitates rapid restoration of islet vascularization. However, the development of fibrosis suggests massive cellular death after transplantation. This study tested the hypothesis that islet graft function is limited by hypoxia-related death early after intramuscular transplantation, but that this can be overcome by cotransplantation of an oxygen carrier, that is, polymerized bovine hemoglobin (PolyHb). Methods. Two hundred islets were transplanted with or without different doses of PolyHb intramuscularly to nondiabetic C57BL/6 and diabetic C57BL/6 nu/nu mice. beta-cell hypoxia and apoptosis were evaluated by immunohistochemistry after injection of the biochemical marker pimonidazole or by staining for caspase-3, respectively. Blood glucose concentrations were monitored for 30 days after islet transplantation and animals were then subjected to an intravenous glucose tolerance test. Results. Substantial hypoxia was observed in control islet grafts during the first 4 days after transplantation. Cotransplantation of PolyHb resulted in a dose-dependent reduction of beta-cell hypoxia, but beta-cell apoptosis was only reduced by cotransplantation of low-dose PolyHb (0.03 mg/g body weight) due to the inflammatory effects of higher PolyHb concentrations. Cotransplantation of low-dose PolyHb resulted in improved islet graft function 30 days after transplantation in diabetic mice, with a glucose tolerance comparable to transplantation of 50% more islets. Conclusion. We conclude that cotransplantation of islets with PolyHb can be used to effectively bridge the critical hypoxic phase immediately after transplantation, improve islet graft function, and reduce the number of islets needed for successful intramuscular transplantation.
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