| 1. |
- Carlbom, Lina, et al.
(författare)
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[(11)C]5-Hydroxy-Tryptophan PET for Assessment of Islet Mass During Progression of Type 2 Diabetes
- 2017
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 66:5, s. 1286-1292
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Tidskriftsartikel (refereegranskat)abstract
- [(11)C]5-hydroxy-tryptophan ([(11)C]5-HTP) PET of the pancreas has been shown to be a surrogate imaging biomarker of pancreatic islet mass. The change in islet mass in different stages of type 2 diabetes (T2D) as measured by non-invasive imaging is currently unknown. Here, we describe a cross-sectional study where subjects at different stages of T2D development with expected stratification of pancreatic islet mass were examined in relation to non-diabetic individuals. The primary outcome was the [(11)C]5-HTP uptake and retention in pancreas, as a surrogate marker for the endogenous islet mass.We found that metabolic testing indicated a progressive loss of beta cell function, but that this was not mirrored by a decrease in [(11)C]5-HTP tracer accumulation in the pancreas. This provides evidence of retained islet mass despite decreased beta cell function. The results herein indicates that beta cell dedifferentiation, and not necessarily endocrine cell loss, constitute a major cause of beta cell failure in T2D.
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| 2. |
- Carlsson, Per-Ola, et al.
(författare)
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Preserved Beta-Cell Function in Type 1 Diabetes by Mesenchymal Stromal Cells
- 2015
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 64:2, s. 587-592
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Tidskriftsartikel (refereegranskat)abstract
- The retention of endogenous insulin secretion in type 1 diabetes is an attractive clinical goal, which opens possibilities for long-term restoration of glucose metabolism. Mesenchymal stromal cells (MSCs) constitute, based on animal studies, a promising interventional strategy for the disease. This prospective clinical study describes the translation of this cellular intervention strategy to patients with recent onset type 1 diabetes. Twenty adult patients with newly diagnosed type 1 diabetes were enrolled and randomized to MSC treatment or to the control group. Residual beta-cell function was analyzed as C-peptide concentrations in blood in response to a mixed meal tolerance test (MMTT) at one-year follow-up. In contrast to the patients in the control arm, who showed loss in both C-peptide peak values and C-peptide when calculated as area under the curve during the first year, these responses were preserved or even increased in the MSC-treated patients. Importantly, no side effects of MSC treatment were observed. We conclude that autologous MSC treatment in new onset type 1 diabetes constitute a safe and promising strategy to intervene in disease progression and preserve beta-cell function.
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| 3. |
- Eriksson, Olof, et al.
(författare)
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In Vivo Visualization of beta-Cells by Targeting of GPR44
- 2018
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 67:2, s. 182-192
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Tidskriftsartikel (refereegranskat)abstract
- GPR44 expression has recently been described as highly beta-cell selective in the human pancreas and constitutes a tentative surrogate imaging biomarker in diabetes. A radiolabeled small-molecule GPR44 antagonist, [C-11]AZ12204657, was evaluated for visualization of beta-cells in pigs and non-human primates by positron emission tomography as well as in immunodeficient mice transplanted with human islets under the kidney capsule. In vitro autoradiography of human and animal pancreatic sections from subjects without and with diabetes, in combination with insulin staining, was performed to assess beta-cell selectivity of the radiotracer. Proof of principle of in vivo targeting of human islets by [C-11]AZ12204657 was shown in the immunodeficient mouse transplantation model. Furthermore, [C-11]AZ12204657 bound by a GPR44-mediated mechanism in pancreatic sections from humans and pigs without diabetes, but not those with diabetes. In vivo [C-11]AZ12204657 bound specifically to GPR44 in pancreas and spleen and could be competed away dose-dependently in nondiabetic pigs and nonhuman primates. [C-11]AZ12204657 is a first-in-class surrogate imaging biomarker for pancreatic beta-cells by targeting the protein GPR44.
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| 4. |
- Eriksson, Olof, et al.
(författare)
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Positron Emission Tomography to Assess the Outcome of Intraportal Islet Transplantation
- 2016
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Ingår i: Diabetes. - : American Diabetes Association. - 1939-327X .- 0012-1797. ; 65:9, s. 2482-2489
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Tidskriftsartikel (refereegranskat)abstract
- No imaging methodology currently exists to monitor viable islet mass after clinical intraportal islet transplantation. We investigated the potential of the endocrine positron emission tomography (PET) marker [11C]5-hydroxytryptophan ([11C]5-HTP) for this purpose. In a preclinical proof-of-concept study, the ex vivo and in vivo [11C]5-HTP signal was compared with the number of islets transplanted in rats. In a clinical study, human subjects with an intraportal islet graft (n = 8) underwent two [11C]5-HTP PET and MRI examinations 8 months apart. The tracer concentration in the liver as a whole, or in defined hotspots, was correlated to measurements of islet graft function. In rat, hepatic uptake of [11C]5-HTP correlated with the number of transplanted islets. In human subjects, uptake in hepatic hotspots showed a correlation with metabolic assessments of islet function. Change in hotspot standardized uptake value (SUV) predicted loss of graft function in one subject, whereas hotspot SUV was unchanged in subjects with stable graft function. The endocrine marker [11C]5-HTP thus shows a correlation between hepatic uptake and transplanted islet function and promise as a tool for noninvasive detection of viable islets. The evaluation procedure described can be used as a benchmark for novel agents targeting intraportally transplanted islets.
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| 5. |
- Kabra, Uma D, et al.
(författare)
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Direct Substrate Delivery into Mitochondrial-Fission Deficient Pancreatic Islets Rescues Insulin Secretion
- 2017
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 66:5, s. 1247-1257
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Tidskriftsartikel (refereegranskat)abstract
- In pancreatic beta cells, mitochondrial bioenergetics control glucose-stimulated insulin secretion (GSIS). Mitochondrial dynamics are generally associated with quality control, maintaining the functionality of bioenergetics. By acute pharmacological inhibition of mitochondrial fission protein Drp1, we here demonstrate that mitochondrial fission is necessary for GSIS in mouse and human islets. We confirm that genetic silencing of Drp1 increases mitochondrial proton leak in MIN6 cells. However, our comprehensive analysis of pancreatic islet bioenergetics reveals that Drp1 does not control insulin secretion via its effect on proton leak but instead via modulation of glucose-fuelled respiration. Notably, pyruvate fully rescues the impaired insulin secretion of fission-deficient beta cells, demonstrating that defective mitochondrial dynamics solely impact substrate supply upstream of oxidative phosphorylation. The present findings provide novel insights in how mitochondrial dysfunction may cause pancreatic beta cell failure. In addition, the results will stimulate new thinking in the intersecting fields of mitochondrial dynamics and bioenergetics, as treatment of defective dynamics in mitochondrial diseases appears to be possible by improving metabolism upstream of mitochondria.
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| 6. |
- Korsgren, Erik, et al.
(författare)
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An Apparent Deficiency of Lymphatic Capillaries in the Islets of Langerhans in the Human Pancreas
- 2016
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 65:4, s. 1004-1008
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Tidskriftsartikel (refereegranskat)abstract
- The lymphatic system is crucial for efficient immune surveillance and for the maintenance of a physiological pressure in the interstitial space. Even so, almost no information is available concerning the lymph drainage of the islets of Langerhans in the human pancreas. lmmunohistochemical staining allowed us to distinguish lymphatic capillaries from blood capillaries. Almost no lymphatic capillaries were found within the islets in pancreatic biopsy specimens from subjects without diabetes or from subjects with type 1 or type 2 diabetes. Lymphatic capillaries were, however, found at the islet exocrine interface, frequently located along blood capillaries and other fibrotic structures within or close to the islet capsule. Lymphatic capillaries were regularly found in the exocrine pancreas, with small lymphatic vessels located close to and around acini. Larger collecting lymphatic vessels were located in fibrotic septa between the exocrine lobules and adjacent to the ductal system of the pancreas. In summary, we report a pronounced deficiency of lymphatic capillaries in human islets, a finding with implications for immune surveillance and the regulation of interstitial fluid transport in the endocrine pancreas as well as for the pathophysiology of both type 1 and type 2 diabetes.
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| 7. |
- Korsgren, Olle
(författare)
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Islet Encapsulation : Physiological Possibilities and Limitations
- 2017
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Ingår i: Diabetes. - : AMER DIABETES ASSOC. - 0012-1797 .- 1939-327X. ; 66:7, s. 1748-1754
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Tidskriftsartikel (refereegranskat)abstract
- A logical cure for type 1 diabetes (T1D) involves replacing the lost insulin-producing cells with new ones, preferably cells from a well-characterized and unlimited source of human insulin-producing cells. This straightforward and simple solution to provide a cure for T1D is immensely attractive but entails at least two inherent and thus far unresolved hurdles: 1) provision of an unlimited source of functional human insulin-producing cells and 2) prevention of rejection without the side effects of systemic immunosuppression. Generation of transplantable insulin-producing cells from human embryonic stem cells or induced pluripotent stem cells is at present close to reality, and we are currently awaiting the first clinical studies. Focus is now directed to foster development of novel means to control the immune system to enable large-scale clinical application. Encapsulation introduces a physical barrier that prevents access of immune cells to the transplanted cells but also hinders blood vessel ingrowth. Therefore, oxygen, nutrient, and hormonal passage over the encapsulation membrane is solely dependent on diffusion over the immune barrier, contributing to delays in glucose sensing and insulin secretion kinetics. This Perspective focuses on the physiological possibilities and limitations of an encapsulation strategy to establish near-normoglycemia in subjects with T1D, assuming that glucose-responsive insulin-producing cells are available for transplantation.
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| 8. |
- Krogvold, Lars, et al.
(författare)
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Detection of a low-grade enteroviral infection in the islets of Langerhans of living patients newly diagnosed with type 1 diabetes
- 2015
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 64:5, s. 1682-1687
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Tidskriftsartikel (refereegranskat)abstract
- The Diabetes Virus Detection study (DiViD) is the first to examine fresh pancreatic tissue at the diagnosis of type 1 diabetes for the presence of viruses. Minimal pancreatic tail resection was performed 3-9 weeks after onset of type 1 diabetes in 6 adult patients (age 24-35 years). The presence of enteroviral capsid protein 1 (VP1) and the expression of class I HLA were investigated by immunohistochemistry. Enterovirus RNA was analyzed from isolated pancreatic islets and from fresh frozen whole pancreatic tissue using PCR and sequencing. Non-diabetic organ donors served as controls. VP1 was detected in the islets of all type 1 diabetes patients (2 of 9 controls). Hyperexpression of class I HLA molecules was found in the islets of all patients (1 of 9 controls). Enterovirus specific RNA sequences were detected in 4 of 6 cases (0 of 6 controls). The results were confirmed in different laboratories. Only 1.7 % of the islets contained VP1 positive cells and the amount of enterovirus RNA was low. The results provides evidence for the presence of enterovirus in pancreatic islets of type 1 diabetic patients, being consistent with the possibility that a low grade enteroviral infection in the pancreatic islets contribute to disease progression in humans.
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| 9. |
- Krogvold, Lars, et al.
(författare)
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Function of Isolated Pancreatic Islets From Patients at Onset of Type 1 Diabetes : Insulin Secretion Can Be Restored After Some Days in a Nondiabetogenic Environment In Vitro: Results From the DiViD Study
- 2015
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Ingår i: Diabetes. - : American Diabetes Association. - 0012-1797 .- 1939-327X. ; 64:7, s. 2506-2512
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Tidskriftsartikel (refereegranskat)abstract
- The understanding of the etiology of type 1 diabetes (T1D) remains limited. One objective of the Diabetes Virus Detection (DiViD) study was to collect pancreatic tissue from living subjects shortly after the diagnosis of T1D. Here we report the insulin secretion ability by in vitro glucose perifusion and explore the expression of insulin pathway genes in isolated islets of Langerhans from these patients. Whole-genome RNA sequencing was performed on islets from six DiViD study patients and two organ donors who died at the onset of T1D, and the findings were compared with those from three nondiabetic organ donors. All human transcripts involved in the insulin pathway were present in the islets at the onset of T1D. Glucose-induced insulin secretion was present in some patients at the onset of T1D, and a perfectly normalized biphasic insulin release was obtained after some days in a nondiabetogenic environment in vitro. This indicates that the potential for endogenous insulin production is good, which could be taken advantage of if the disease process was reversed at diagnosis.
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| 10. |
- Nano, Rita, et al.
(författare)
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Islets for Research : Nothing Is Perfect, but We Can Do Better
- 2019
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Ingår i: Diabetes. - : AMER DIABETES ASSOC. - 0012-1797 .- 1939-327X. ; 68:8, s. 1541-1543
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Tidskriftsartikel (refereegranskat)abstract
- In December 2018, Diabetes and Diabetologia began requiring authors of papers reporting data obtained from studies on human islets to report critical characteristics of the human islets used for research. The islet community was asked to provide feedback on it. Here is the contribution by the European Consortium for Islet Transplantation.
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