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Adenovirus-Mediated Expression of the Anticoagulant Hirudin in Human Islets: A Tool to Make the Islets Biocompatible to Blood
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology, Clinical Immunology.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology, Clinical Immunology.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Oncology, Radiology and Clinical Immunology, Clinical Immunology.
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2006 (English)In: Cell Transplantation, ISSN 0963-6897, E-ISSN 1555-3892, Vol. 15, no 8-9, 759-767 p.Article in journal (Refereed) Published
Abstract [en]

Human islets induce an injurious clotting reaction at the time of transplantation. A potential strategy to counteract this reaction would be to allow the islets to express hirudin, a protein with direct anticoagulative activity. Human islets were transduced with an adenoviral vector encoding hirudin, an empty corresponding vector, or left untreated. Islet culture supernatants were analyzed for hirudin using an ELISA, a chromogenic substrate assay based on the thrombin-binding properties of hirudin and in a whole blood viscosimetry assay. Immunohistochemical evaluation and determination of hirudin content revealed an abundant expression of hirudin after transduction. Hirudin content in transduced islets was in the range of the insulin content levels. A delay in human whole blood clotting time could be observed after addition of supernatants taken from islet cultures expressing hirudin. However, transduced islets showed an impaired glucose-stimulated insulin release, but could readily be retrieved 6 weeks after transplantation to athymic mice. A marked expression and secretion of hirudin with functional capacity can be induced in human islets using an adenoviral vector. The impairment in glucose-stimulated insulin release in hirudin-secreting islets, compared to controls, indicates that the additional protein synthesis affects the functional capacity of the islets.

Place, publisher, year, edition, pages
2006. Vol. 15, no 8-9, 759-767 p.
Keyword [en]
Transplantation, Coagulation, Human islets of Langerhans, Hirudin, Adenoviral vector
National Category
Medical and Health Sciences
Identifiers
URN: urn:nbn:se:uu:diva-96503ISI: 000243371200008PubMedID: 17269446OAI: oai:DiVA.org:uu-96503DiVA: diva2:171100
Available from: 2007-11-15 Created: 2007-11-15 Last updated: 2017-12-14Bibliographically approved
In thesis
1. Pancreatic Islet Transplantation: Modifications of Islet Properties to Improve Graft Survival
Open this publication in new window or tab >>Pancreatic Islet Transplantation: Modifications of Islet Properties to Improve Graft Survival
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

During the past decade clinical islet transplantation has become a viable strategy for curing type 1 diabetes. The limited supply of organs, together with the requirement for islets from multiple donors to achieve insulin independence, has greatly limited the application of this approach.

The islets are infused into the liver via the portal vein, and once exposed to the blood, the grafted tissue has been shown to be damaged by the instant blood-mediated inflammatory reaction (IBMIR), which is characterized by coagulation and complement activation as well as leukocyte infiltration into the islets. Islet revascularization is a subsequent critical step for the long-term function of the transplanted graft, which may partially be impeded by the IBMIR.

In this thesis, we have explored novel strategies for circumventing the effects of the IBMIR and facilitating islet revascularization.

Systemic inhibitors of the IBMIR are typically associated with an increased risk of bleeding. We therefore evaluated alternative strategies for modulating the islets prior to transplantation. We demonstrated, using an adenoviral vector, that a high level of expression and secretion of the anticoagulant hirudin could be induced in human islets. An alternative approach to limiting the IBMIR was developed in which anticoagulant macromolecular heparin complexes were conjugated to the islet surface. This technique proved effective in limiting the IBMIR in both an in vitro blood loop model and an allogeneic porcine model of islet transplantation. An increased adhesion of endothelial cells to the heparin-coated islet surface was demonstrated, as was the capacity of the heparin conjugate to bind the angiogenic factors VEGF and FGF; these results have important implications for the revascularization process.

The outcome of the work in this thesis suggests that modulation of the islet surface is an attractive alternative to systemic therapy as a strategy for preventing the IBMIR. Moreover, the same techniques can be employed to induce revascularization and improve the engraftment of the transplanted islets. Ultimately, improved islet viability and engraftment will make islet transplantation a more effective procedure and increase the number of patients whose diabetes can be cured.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2007. 60 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 297
Keyword
Medicine, Diabetes, islet transplantation, islets of Langerhans, coagulation activation, IBMIR, hirudin, heparin, growth factor, angiogenesis, Medicin
Identifiers
urn:nbn:se:uu:diva-8333 (URN)978-91-554-7039-5 (ISBN)
Public defence
2007-12-07, Rudbecksalen, Rudbecklaboratoriet, Dag Hammarskjöldsväg 20, Uppsala, 09:15
Opponent
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Available from: 2007-11-15 Created: 2007-11-15 Last updated: 2011-01-12Bibliographically approved

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