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- Grapensparr, Liza
(författare)
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Auxiliary Cells for the Vascularization and Function of Endogenous and Transplanted Islets of Langerhans
- 2017
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Type 1 diabetes develops through the progressive destruction of the insulin-producing beta-cells. Regeneration or replacement of beta-cells is therefore needed to restore normal glucose homeostasis. Presently, normoglycemia can be achieved by the transplantation of whole pancreas or isolated islets of Langerhans. Islet transplantation can be performed through a simple laparoscopic procedure, but the long-term graft survival is low due to poor revascularization and early cell death.This thesis examined the possibility of using different auxiliary cells (Schwann cells, endothelial progenitor cells, and neural crest stem cells) to improve the engraftment and function of endogenous and transplanted islets.Co-transplantation of Schwann cells with islets improved islet graft function early after transplantation, and caused an increased islet mass at one month posttransplantation. However, the vascular densities of these grafts were decreased, which also related to an impaired graft function.Islet grafts containing endothelial progenitor cells had a superior vascular density, with functional chimeric blood vessels and substantially higher blood perfusion and oxygen tension than control transplants.By culturing and transplanting islets together with neural crest stem cells it was found that islets exposed to these cells had a higher beta-cell proliferation compared with control islets. At one month posttransplantation, the grafts with neural crest stem cells also had a superior vascular- and neural density.The potential of intracardially injected neural crest stem cells to home to the pancreas and ameliorate hyperglycemia in diabetic mice was investigated. During a three-week period after such cell treatment blood glucose concentrations decreased, but were not fully normalized. Neural crest stem cells were present in more than 10% of the pancreatic islets at two days postinjection, at which time the beta-cell proliferation was markedly increased when compared with islets of saline-treated diabetic animals. Three weeks later, a doubled beta-cell mass was observed in animals receiving neural crest stem cells.In summary, islets can easily be transplanted together with different auxiliary cells. Some of these cells provide the possibility of improving vascular- and neural engraftment, as well as beta-cell growth and survival. Systemic administration of neural crest stem cells holds the potential of regenerating the endogenous beta-cells.
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| 2. |
- Grapensparr, Liza, et al.
(författare)
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Bioengineering with Endothelial Progenitor Cells Improves the Vascular Engraftment of Transplanted Human Islets
- 2018
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Ingår i: Cell Transplantation. - : SAGE Publications. - 0963-6897 .- 1555-3892. ; 27:6, s. 948-956
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Tidskriftsartikel (refereegranskat)abstract
- Pancreatic islets isolated for transplantation are disconnected from their vascular supply and need to establish a new functional network posttransplantation. Due to poor revascularization, prevailing hypoxia with correlating increased apoptosis rates in experimental studies can be observed for months posttransplantation. Endothelial progenitor cells (EPCs) are bone marrow-derived cells that promote neovascularization. The present study tested the hypothesis that EPCs, isolated from human umbilical cord blood, could be coated to human islet surfaces and be used to promote islet vascular engraftment. Control or EPC bioengineered human islets were transplanted into the renal subcapsular space of nonobese diabetic/severe combined immunodeficiency mice. Four weeks posttransplantation, graft blood perfusion and oxygen tension were measured using laser Doppler flowmetry and Clark microelectrodes, respectively. Vessel functionality was also assessed by in vivo confocal imaging. The vascular density and the respective contribution of human and recipient endothelium were assessed immunohistochemically by staining for human and mouse CD31. Islet grafts with EPCs had substantially higher blood perfusion and oxygen tension than control transplants. Furthermore, analysis of the vascular network of the grafts revealed that grafts containing EPC bioengineered islets had a superior vascular density compared with control grafts, with functional chimeric blood vessels. We conclude that a simple procedure of surface coating with EPCs provides a possibility to improve the vascular engraftment of transplanted human islets. Established protocols are also easily applicable for intraportal islet transplantation in order to obtain a novel directed cellular therapy at the site of implantation in the liver.
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| 3. |
- 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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| 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. |
- Jansson, Leif, et al.
(författare)
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Pancreatic islet blood flow and its measurement
- 2016
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Ingår i: Upsala Journal of Medical Sciences. - : Uppsala Medical Society. - 0300-9734 .- 2000-1967. ; 121:2, s. 81-95
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Forskningsöversikt (refereegranskat)abstract
- Pancreatic islets are richly vascularized, and islet blood vessels are uniquely adapted to maintain and support the internal milieu of the islets favoring normal endocrine function. Islet blood flow is normally very high compared with that to the exocrine pancreas and is autonomously regulated through complex interactions between the nervous system, metabolites from insulin secreting beta-cells, endothelium derived mediators, and hormones. The islet blood flow is normally coupled to the needs for insulin release and is usually disturbed during glucose intolerance and overt diabetes. The present review provides a brief background on islet vascular function and especially focuses on available techniques to measure islet blood perfusion. The gold standard for islet blood flow measurements in experimental animals is the microsphere technique, and its advantages and disadvantages will be discussed. In humans there are still no methods to measure islet blood flow selectively, but new developments in radiological techniques hold great hopes for the future.
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