| 1. |
- Vasylovska, Svitlana, et al.
(författare)
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Generation of human induced pluripotent stem cell (iPSC) lines (UUMCBi001-A, UUMCBi002-A) from two healthy donors
- 2021
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Ingår i: Stem Cell Research. - : Elsevier. - 1873-5061 .- 1876-7753. ; 50
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Tidskriftsartikel (refereegranskat)abstract
- Availability of numerous high-quality iPSC lines is needed to overcome donor-associated variability caused by genetic background effects. We generated two human iPSC lines from dermal fibroblasts of two healthy females using Sendai virus reprogramming. Quality assessment of the iPSC lines confirmed the expression of pluripotency markers, trilineage differentiation capacity and absence of exogenous expression of reprogramming factors. Both iPSC lines were genetically stable with a genotype that matched the fibroblast lines of donors. These iPSC lines add to available reference lines as a resource for disease modeling of polygenic and multifactorial diseases, for evaluation of differentiation protocols and toxicology screening.
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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. |
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| 4. |
- Olerud, Johan, 1977-
(författare)
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Role of Thrombospondin-1 in Endogenous and Transplanted Pancreatic Islets
- 2009
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Type 1 diabetes mellitus is a severe life-long disease with a pronounced risk of developing secondary complications. One way to avoid the latter is to restore the fine tuning of blood glucose homeostasis by transplantation of pancreatic islets. However, isolated islets need to be properly engrafted and to re-establish a vascular network in order to regain function. Earlier studies have shown that pancreatic islets experimentally transplanted to e.g. the liver or the kidney become poorly revascularized. In the present thesis, mice deficient of the angiostatic factor thrombospondin-1 (TSP-1) were found to have an impaired beta-cell function. Development of this beta-cell dysfunction was prevented by treatment of TSP-1 deficient mice from birth with the TGFbeta-1 activating sequence of TSP-1. TSP-1 in islets was predominantly expressed in the endothelial cells. Isolated islet endothelial cells was observed to have a low proliferatory and migratory capacity towards angiogenic stimuli, but this could be reversed by neutralizing antibodies to the angiostatic factors alpha1-antitrypsin, endostatin or TSP-1. Transient downregulation of TSP-1 expression in mouse islet cells prior to transplantation improved graft revascularization, blood perfusion, oxygenation and function when evaluated one-month post-transplantation. The same result was achieved when islets or recipients of islets were pre-treated with the hormone prolactin one-month post-transplantation. The present study illustrates the importance of the angiostatic factor TSP-1 for islet beta-cell function and engraftment of islets following transplantation. Interference with TSP-1 can possibly be used to improve the results of clinical islet transplantation.
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| 5. |
- 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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| 6. |
- Espes, Daniel, 1985-, et al.
(författare)
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Pregnancy induces pancreatic insulin secretion in women with long-standing type 1 diabetes
- 2022
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Ingår i: BMJ Open Diabetes Research & Care. - : BMJ Publishing Group Ltd. - 2052-4897. ; 10:6
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Tidskriftsartikel (refereegranskat)abstract
- Introduction: Pregnancy entails both pancreatic adaptations with increasing beta-cell mass and immunological alterations in healthy women. In this study, we have examined the effects of pregnancy on beta-cell function and immunological processes in long-standing type 1 diabetes (L-T1D).Research design and methods: Fasting and stimulated C-peptide were measured after an oral glucose tolerance test in pregnant women with L-T1D (n=17) during the first trimester, third trimester, and 5-8 weeks post partum. Two 92-plex Olink panels were used to measure proteins in plasma. Non-pregnant women with L-T1D (n=30) were included for comparison.Results: Fasting C-peptide was detected to a higher degree in women with L-T1D during gestation and after parturition (first trimester: 64.7%, third trimester: 76.5%, and post partum: 64.7% vs 26.7% in non-pregnant women). Also, total insulin secretion and peak C-peptide increased during pregnancy. The plasma protein levels in pregnant women with L-T1D was dynamic, but few analytes were functionally related. Specifically, peripheral levels of prolactin (PRL), prokineticin (PROK)-1, and glucagon (GCG) were elevated during gestation whereas levels of proteins related to leukocyte migration (CCL11), T cell activation (CD28), and antigen presentation (such as CD83) were reduced.Conclusions: In summary, we have found that some C-peptide secretion, that is, an indirect measurement of endogenous insulin production, is regained in women with L-T1D during pregnancy, which might be attributed to elevated peripheral levels of PRL, PROK-1, or GCG.
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| 7. |
- Espes, Daniel, 1985-
(författare)
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Engraftment of Pancreatic Islets in Alternative Transplantation Sites and the Feasibility of in vivo Monitoring of Native and Transplanted Beta-Cell Mass
- 2016
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Islet transplantation is a possible curative treatment for type 1 diabetes (T1D). Currently the liver dominates as implantation site, despite the many challenges encountered at this site.Acute hypoxia in islets transplanted to muscle and omentum, two possible alternative sites, was prevailing. However, it was rapidly reversed at both implantation sites, in contrast to when islets were transplanted intraportally. At the intramuscular site hypoxia was further relieved by co-transplantation of an oxygen carrier, polymerized hemoglobin, which also improved the functional outcome. The complement system was activated after islet transplantation to muscle, but did not hamper graft function.Both mouse and human islets transplanted to omentum become well re-vascularized and have a functional blood flow and oxygenation comparable with that of endogenous islets. Animals transplanted with islets to the omentum had a superior graft function compared with animals receiving intraportal islet grafts.Alloxan-diabetic animals were cured with a low number of islets both when the islets were implanted in the omentum and muscle. The islet grafts responded adequately to both glucose and insulin and displayed a favorable mRNA gene expression profile.A challenge in diabetes research and in islet transplantation is that there are no established techniques for quantifying beta-cell mass in vivo. By using radiolabeled Exendin-4, a GLP-1 receptor agonist, beta-cell mass after transplantation to muscle of mice was quantified. The results may well be translated to the clinical setting.By comparing the pancreatic accumulation of [11C]5-hydroxy tryptophan ([11C]5-HTP) as detected by positron emission tomography (PET) in T1D patients with that of healthy controls, a 66% decrease was observed. This may in fact represent the loss of beta-cells, taking into account that other cells within the islets of Langerhans are largely unaffected in T1D. In conclusion, the data presented support the use of alternative implantation sites for islet transplantation. In addition to improving the functional outcome this may enable more transplantations since the number of transplanted islets may be reduced. The techniques investigated for quantifying transplanted and endogenous beta-cell mass may greatly improve our knowledge of the pathophysiology of T1D and become a valuable tool for evaluation of beta-cell mass.
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| 8. |
- Espes, Daniel, et al.
(författare)
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Quantification of Beta-Cell Mass in Intramuscular Islet Grafts using Radiolabeled Exendin-4
- 2016
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Ingår i: Transplantation Direct. - 2373-8731. ; 2:8
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Tidskriftsartikel (refereegranskat)abstract
- Background: There is an increasing interest in alternative implantation sites to the liver for islet transplantation. Intramuscular implantation has even been tested clinically. Possibilities to monitor [beta]-cell mass would be of huge importance not only for the understanding of islet engraftment but also for the decision of changing the immunosuppressive regime. We have therefore evaluated the feasibility of quantifying intramuscular [beta]-cell mass using the radiolabeled glucagon like peptide-1 receptor agonist DO3A-VS-Cys40-Exendin-4.Methods: One hundred to 400 islets were transplanted to the abdominal muscle of nondiabetic mice. After 3 to 4 weeks, 0.2 to 0.5 MBq [177Lu]DO3A-VS-Cys40-Exendin-4 was administered intravenously. Sixty minutes postinjection abdominal organs and graft bearing muscle were retrieved, and the radioactive uptake measured in a well counter within 10 minutes. The specific uptake in native and transplanted islets was assessed by autoradiography. The total insulin-positive area of the islet grafts was determined by immunohistochemistry.Results: Intramuscular islet grafts could easily be visualized by this tracer, and the background uptake was very low. There was a linear correlation between the radioactivity uptake and the number of transplanted islets, both for standardized uptake values and the total radiotracer uptake in each graft (percentage of injected dose). The quantified total insulin area of surviving [beta] cells showed an even stronger correlation to both standardized uptake values (R = 0.96, P = 0.0002) and percentage of injected dose (R = 0.88, P = 0.0095). There was no correlation to estimated [alpha] cell mass.Conclusions: [177Lu]DO3A-VS-Cys40-Exendin-4 could be used to quantify [beta]-cell mass after experimental intramuscular islet transplantation. This technique may well be transferred to the clinical setting by exchanging Lutetium-177 radionuclide to a positron emitting Gallium-68.
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| 9. |
- 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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| 10. |
- Espes, Daniel, 1985-, et al.
(författare)
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Function and Gene Expression of Islets Experimentally Transplanted to Muscle and Omentum
- 2020
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Ingår i: Cell Transplantation. - THOUSAND OAKS, CA USA : SAGE Publications. - 0963-6897 .- 1555-3892. ; 29, s. 1-10
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Tidskriftsartikel (refereegranskat)abstract
- Islet transplantation to the liver is a potential curative treatment for patients with type 1 diabetes. Muscle and the greater omentum are two alternative implantation sites, which can provide excellent engraftment and hold potential as future sites for stem-cell-derived beta-cell replacement. We evaluated the functional outcome after islet transplantation to muscle and omentum and found that alloxan-diabetic animals were cured with a low number of islets (200) at both sites. The cured animals had a normal area under the curve blood glucose response to intravenous glucose, albeit animals with intramuscular islet grafts had increased 120-min blood glucose levels. They also demonstrated an exaggerated counter regulatory response to hypoglycemia. The expression of genes important for beta-cell function was, at both implantation sites, comparable to that in native pancreatic islets. The gene expression of insulin (INS1 and INS2) and glucose transporter-2 was even increased, and the expression of lactate dehydrogenase decreased, at both sites when compared to native islets. We conclude that muscle and omentum provide excellent conditions for engraftment of transplanted islets. When compared to control, 200 islets implanted to the omentum displayed a restored glucose tolerance, whereas animals with intramuscular islet grafts of similar size displayed mild glucose intolerance.
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