| 1. |
- Drott, Carl Johan, et al.
(författare)
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Sustained Beta-Cell Dysfunction but Normalized Islet Mass in Aged Thrombospondin-1 Deficient Mice
- 2012
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Ingår i: PLOS ONE. - : Public Library of Science (PLoS). - 1932-6203. ; 7:10, s. e47451-
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Tidskriftsartikel (refereegranskat)abstract
- Pancreatic islet endothelial cells have in recent years been shown to support beta-cell mass and function by paracrine interactions. Recently, we identified an islets endothelial-specific glycoprotein, thrombospondin-1 (TSP-1), that showed to be of importance for islet angiogenesis and beta-cell function in young mice. The present study aimed to investigate long-term consequences for islet morphology and beta-cell function of TSP-1 deficiency. Islet and beta-cell mass were observed increased at 10-12 weeks of age in TSP-1 deficient mice, but were normalized before 16 weeks of age when compared to wild-type controls. Islet vascularity was normal in 10-12 and 16-week-old TSP-1 deficient animals, whereas islets of one-year-old animals lacking TSP-1 were hypervascular. Beta-cell dysfunction in TSP-1 deficient animals was present at similar magnitudes between 10-12 and 52 weeks of age, as evaluated by glucose tolerance tests. The insulin secretion capacity in vivo of islets in one-year-old TSP-1 deficient animals was only similar to 15% of that in wild-type animals. Using a transplantation model, we reconstituted TSP-1 in adult TSP-deficient islets. In contrast to neonatal TSP-1 deficient islets that we previously reported to regain function after TSP-1 reconstitution, adult islets failed to recover. We conclude that TSP-1 deficiency in islets causes changing vascular and endocrine morphological alterations postnatally, but is coupled to a chronic beta-cell dysfunction. The beta-cell dysfunction induced by TSP-1 deficiency is irreversible if not substituted early in life.
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| 2. |
- Sällström, Johan, et al.
(författare)
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High-protein-induced glomerular hyperfiltration is independent of the tubuloglomerular feedback mechanism and nitric oxide synthases
- 2010
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Ingår i: American Journal of Physiology. Regulatory Integrative and Comparative Physiology. - : American Physiological Society. - 0363-6119 .- 1522-1490. ; 299:5, s. R1263-R1268
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Tidskriftsartikel (refereegranskat)abstract
- A high protein intake is associated with increased glomerular filtration rate (GFR), which has been suggested to be mediated by reduced signaling of the tubuloglomerular feedback (TGF) mechanism. Nitric oxide (NO) has been shown to contribute to high protein-induced glomerular hyperfiltration, but the specific NO synthase (NOS) isoform responsible is not clear. In this study, a model for high-proteininduced hyperfiltration in conscious mice was developed. Using this model, we investigated the role of TGF using adenosine A(1)-receptor knockout mice lacking the TGF mechanism. Furthermore, the role of the different NOS isoforms was studied using neuronal-, inducible-, and endothelial-NOS knockout mice, and furthermore, wild-type mice acutely administered with the unspecific NOS inhibitor N-omega-nitro-L-arginine methyl ester (100 mg/kg). GFR was measured consecutively in mice given a low-protein diet (8% casein) for 10 days, followed by a high-protein diet (50% casein) for 10 days. All mice developed high protein-induced hyperfiltration to a similar degree. These results demonstrate that high protein-induced glomerular hyperfiltration is independent of the TGF mechanism and NOS isoforms.
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| 3. |
- Carlsson, Per-Ola, et al.
(författare)
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Transplantation of macroencapsulated human islets within the bioartificial pancreas βAir to patients with type 1 diabetes mellitus
- 2018
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Ingår i: American Journal of Transplantation. - : Elsevier BV. - 1600-6135 .- 1600-6143. ; 18:7, s. 1735-1744
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Tidskriftsartikel (refereegranskat)abstract
- Macroencapsulation devices provide the dual possibility to immunoprotect transplanted cells while also being retrievable; the latter bearing importance for safety in future trials with stem-cell derived cells. However, macroencapsulation entails a problem with oxygen supply to the encapsulated cells. The βAir device solves this with an incorporated refillable oxygen tank. This phase 1 study evaluated the safety and efficacy of implanting the βAir device containing allogeneic human pancreatic islets to patients with type 1 diabetes. Four patients were transplanted with 1-2 βAir devices, each containing 155000-180000 IEQ (i.e. 1800-4600 IEQ per kg body weight), and monitored for 3-6 months, followed by the recovery of devices. Implantation of the βAir device was safe and successfully prevented immunization and rejection of the transplanted tissue. However, although beta cells survived in the device, only minute levels of circulating C-peptide were observed with no impact on metabolic control. Fibrotic tissue with immune cells was formed in capsule surroundings. Recovered devices displayed a blunted glucose-stimulated insulin response, and amyloid formation in the endocrine tissue. We conclude that the βAir device is safe and can support survival of allogeneic islets for several months, although the function of the transplanted cells was limited.
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| 4. |
- Eich, Torsten, 1972-, et al.
(författare)
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Calcium: A Crucial Potentiator for Efficient Enzyme Digestion of the Human Pancreas
- 2018
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Ingår i: Cell Transplantation. - : SAGE Publications. - 0963-6897 .- 1555-3892. ; 27:7, s. 1031-1038
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Tidskriftsartikel (refereegranskat)abstract
- Background: Effective digestive enzymes are crucial for successful islet isolation. Supplemental proteases are essential because they synergize with collagenase for effective pancreatic digestion. The activity of these enzymes is critically dependent on the presence of Ca2+ ions at a concentration of 5-10 mM. The present study aimed to determine the Ca2+ concentration during human islet isolation and to ascertain whether the addition of supplementary Ca2+ is required to maintain an optimal Ca2+ concentration during the various phases of the islet isolation process. Methods: Human islets were isolated according to standard methods and isolation parameters. Islet quality control and the number of isolations fulfilling standard transplantation criteria were evaluated. Ca2+ was determined by using standard clinical chemistry routines. Islet isolation was performed with or without addition of supplementary Ca2+ to reach a Ca2+ of 5 mM. Results: Ca2+ concentration was markedly reduced in bicarbonate-based buffers, especially if additional bicarbonate was used to adjust the pH as recommended by the Clinical Islet Transplantation Consortium. A major reduction in Ca2+ concentration was also observed during pancreatic enzyme perfusion, digestion, and harvest. Additional Ca2+ supplementation of media used for dissolving the enzymes and during digestion, perfusion, and harvest was necessary in order to obtain the concentration recommended for optimal enzyme activity and efficient liberation of a large number of islets from the human pancreas. Conclusions: Ca2+ is to a large extent consumed during clinical islet isolation, and in the absence of supplementation, the concentration fell below that recommended for optimal enzyme activity. Ca2+ supplementation of the media used during human pancreas digestion is necessary to maintain the concentration recommended for optimal enzyme activity. Addition of Ca2+ to the enzyme blend has been implemented in the standard isolation protocols in the Nordic Network for Clinical Islet Transplantation.
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| 5. |
- Friederich, Malou, 1983-, et al.
(författare)
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Identification and distribution of uncoupling protein isoforms in the normal and diabetic rat kidney
- 2009
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Ingår i: Advances in Experimental Medicine and Biology. - New York : Springer. - 0065-2598 .- 2214-8019. - 9780387859972 ; 645, s. 205-212
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Tidskriftsartikel (refereegranskat)abstract
- Uncoupling protein (UCP)-2 and -3 are ubiquitously expressed throughout the body but there is currently no information regarding the expression and distribution of the different UCP isoforms in the kidney. Due to the known cross-reactivity of the antibodies presently available for detection of UCP-2 and -3 proteins, we measured the mRNA expression of UCP-1, -2 and -3 in the rat kidney in order to detect the kidney-specific UCP isoforms. Thereafter, we determined the intrarenal distribution of the detected UCP isoforms using immunohistochemistry. Thereafter, we compared the protein levels in control and streptozotocin-induced diabetic rats using Western blot. Expressions of the UCP isoforms were also performed in brown adipose tissue and heart as positive controls for UCP-1 and 3, respectively. UCP-2 mRNA was the only isoform detected in the kidney. UCP-2 protein expression in the kidney cortex was localized to proximal tubular cells, but not glomerulus or distal nephron. In the medulla, UCP-2 was localized to cells of the medullary thick ascending loop of Henle, but not to the vasculature or parts of the nephron located in the inner medulla. Western blot showed that diabetic kidneys have about 2.5-fold higher UCP-2 levels compared to controls. In conclusion, UCP-2 is the only isoform detectable in the kidney and UCP-2 protein can be detected in proximal tubular cells and cells of the medullary thick ascending loop of Henle. Furthermore, diabetic rats have increased UCP-2 levels compared to controls, but the mechanisms underlying this increase and its consequences warrants further studies.
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| 6. |
- Friederich, Malou, et al.
(författare)
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Uncoupling protein-2 in diabetic kidneys : increased protein expression correlates to increased non-transport related oxygen consumption
- 2008
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Ingår i: Advances in Experimental Medicine and Biology. - Boston, MA : Springer Berlin/Heidelberg. - 0065-2598 .- 2214-8019. ; 614, s. 37-43, s. 37-43
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Tidskriftsartikel (refereegranskat)abstract
- Diabetic patients have an elevated risk to develop renal dysfunction and it has been postulated that altered energy metabolism is involved. We have previously shown that diabetic rats have markedly decreased oxygen availability in the kidney, resulting from increased oxygen consumption. A substantial part of the increased oxygen consumption is unrelated to tubular transport, suggesting decreased mitochondrial efficiency. In this study, we investigated the protein expression of mitochondrial uncoupling protein (UCP)-2 in kidney tissue from control and streptozotocin (STZ)-induced diabetic rats. Protein levels of UCP-2 were measured in adult male control and STZ-diabetic Wistar Furth as well as Sprague Dawley rats in both the kidney cortex and medulla by Western blot technique. Two weeks of hyperglycemia resulted in increased protein levels of UCP-2 in kidneys from both Wistar Furth and Sprague Dawley rats. Both cortical and medullary UCP-2 levels were elevated 2-3 fold above control levels. We conclude that sustained STZ-induced hyperglycemia increases the kidney levels of mitochondrial UCP-2, which could explain the previously reported increase in non-transport related oxygen consumption in diabetic kidneys. The elevated UCP-2 levels may represent an effort to reduce the increased production of superoxide radicals which is evident during diabetes.
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| 7. |
- Grapensparr, Liza, et al.
(författare)
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Co-transplantation of Human Pancreatic Islets With Post-migratory Neural Crest Stem Cells Increases beta-Cell Proliferation and Vascular And Neural Regrowth
- 2015
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Ingår i: Journal of Clinical Endocrinology and Metabolism. - : The Endocrine Society. - 0021-972X .- 1945-7197. ; 100:4, s. E583-E590
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Tidskriftsartikel (refereegranskat)abstract
- Context: Neural crest stem cells (NCSCs) are capable of substantially improving murine islet function by promoting beta-cell proliferation. Objective: The present study aimed to investigate the potential of NCSCs to stimulate human beta-cell proliferation, and improve neural and vascular engraftment of human islets. Design, Setting, and Subjects: Human pancreatic islets from 18 brain-dead cadaveric donors (age range, 19-78 y) were obtained through the Nordic Network for Clinical Islet Transplantation. beta-cell proliferation and graft function was investigated at our experimental laboratory. Intervention and Main Outcome Measures: Human islets were transplanted, either alone or together with spheres of NCSCs. beta-cell proliferation, as well as islet neuralandvascular densities, were assessed by immunohistochemistry. Graft blood perfusion and oxygen tension were measured using laser-Doppler flowmetry and Clark microelectrodes, respectively. Results: Two days posttransplantation, the number of Ki67-positive beta-cells was doubled in human islets that had been exposed to NCSCs. Similar findings were obtained in vitro, as well as with EdU as proliferation marker. Four weeks posttransplantation, NCSC-exposed human islet grafts had much higher neural and vascular densities. The newly formed blood vessels were also functional, given that these human islets had a substantially higher blood perfusion and oxygen tension when compared with control transplants. Conclusion: We conclude that exposure to NCSCs stimulates human beta-cell proliferation, andthat these cells improve both the neural and vascular engraftment of transplanted human islets. NCSCs are a promising cellular therapy for translation into clinical use.
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| 8. |
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| 9. |
- Grapensparr, Liza, et al.
(författare)
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The therapeutic role of endothelial progenitor cells in Type 1 diabetes mellitus
- 2011
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Ingår i: Regenerative Medicine. - 1746-0751 .- 1746-076X. ; 6:5, s. 599-605
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Forskningsöversikt (refereegranskat)abstract
- Pancreatic beta-cells sense and adjust the blood glucose level by secretion of insulin. In Type 1 diabetes mellitus, these insulin-producing cells are destroyed, leaving the patients incapable of regulating blood glucose homeostasis. At the time of diagnosis, most patients still have 20-30% of their original beta-cell mass remaining. These residual beta-cells are targets for intervention therapies aimed at preventing further autoimmune destruction, in addition to increasing the number of existing beta-cells. Such a therapeutic option is highly desirable since it may lead to a full recovery of newly diagnosed patients, with no need for further treatment with immunosuppressant drugs or exogenous insulin administration. In this article, we propose that endothelial progenitor cells, a cell type known to promote and support neovascularization following endothelial injury, may be used as part of a combinational stem cell therapy aimed to improve the vascularization, survival and proliferation of beta-cells.
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| 10. |
- Grouwels, G., et al.
(författare)
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Differentiating neural crest stem cells induce proliferation of cultured rodent islet beta cells
- 2012
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Ingår i: Diabetologia. - : Springer Science and Business Media LLC. - 0012-186X .- 1432-0428. ; 55:7, s. 2016-2025
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Tidskriftsartikel (refereegranskat)abstract
- Aims/hypothesisEfficient stimulation of cycling activity in cultured beta cells would allow the design of new strategies for cell therapy in diabetes. Neural crest stem cells (NCSCs) play a role in beta cell development and maturation and increase the beta cell number in co-transplants. The mechanism behind NCSC-induced beta cell proliferation and the functional capacity of the new beta cells is not known.MethodsWe developed a new in vitro co-culture system that enables the dissection of the elements that control the cellular interactions that lead to NCSC-dependent increase in islet beta cells.ResultsMouse NCSCs were cultured in vitro, first in medium that stimulated their proliferation, then under conditions that supported their differentiation. When mouse islet cells were cultured together with the NCSCs, more than 35% of the beta cells showed cycle activity. This labelling index is more than tenfold higher than control islets cultured without NCSCs. Beta cells that proliferated under these culture conditions were fully glucose responsive in terms of insulin secretion. NCSCs also induced beta cell proliferation in islets isolated from 1-year-old mice, but not in dissociated islet cells isolated from human donor pancreas tissue. To stimulate beta cell proliferation, NCSCs need to be in intimate contact with the beta cells.Conclusions/interpretationCulture of islet cells in contact with NCSCs induces highly efficient beta cell proliferation. The reported culture system is an excellent platform for further dissection of the minimal set of factors needed to drive this process and explore its potential for translation to diabetes therapy.
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