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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
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Medicine, Department of Medical Cell Biology. (Per-Ola Carlsson)
2016 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

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.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2016. , 88 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Medicine, ISSN 1651-6206 ; 1211
Keyword [en]
Type 1 diabetes, Islet transplantation, Alternative implantation sites, Exendin-4, Positron Emission Tomography, 5-hydroxy tryptophan, Beta-cell mass
National Category
Cell and Molecular Biology
Research subject
Medical Cell Biology
Identifiers
URN: urn:nbn:se:uu:diva-282953ISBN: 978-91-554-9551-0 (print)OAI: oai:DiVA.org:uu-282953DiVA: diva2:917922
Public defence
2016-06-01, Sal B22, BMC, Husargatan 3, Uppsala, 09:15 (English)
Opponent
Supervisors
Available from: 2016-05-11 Created: 2016-04-08 Last updated: 2016-06-01
List of papers
1. Cotransplantation of Polymerized Hemoglobin Reduces β-Cell Hypoxia and Improves β-Cell Function in Intramuscular Islet Grafts
Open this publication in new window or tab >>Cotransplantation of Polymerized Hemoglobin Reduces β-Cell Hypoxia and Improves β-Cell Function in Intramuscular Islet Grafts
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2015 (English)In: Transplantation, ISSN 0041-1337, E-ISSN 1534-6080, Vol. 99, no 10, 2077-2082 p.Article in journal (Refereed) Published
Abstract [en]

Background. Muscle is a promising alternative site for islet transplantation that facilitates rapid restoration of islet vascularization. However, the development of fibrosis suggests massive cellular death after transplantation. This study tested the hypothesis that islet graft function is limited by hypoxia-related death early after intramuscular transplantation, but that this can be overcome by cotransplantation of an oxygen carrier, that is, polymerized bovine hemoglobin (PolyHb). Methods. Two hundred islets were transplanted with or without different doses of PolyHb intramuscularly to nondiabetic C57BL/6 and diabetic C57BL/6 nu/nu mice. beta-cell hypoxia and apoptosis were evaluated by immunohistochemistry after injection of the biochemical marker pimonidazole or by staining for caspase-3, respectively. Blood glucose concentrations were monitored for 30 days after islet transplantation and animals were then subjected to an intravenous glucose tolerance test. Results. Substantial hypoxia was observed in control islet grafts during the first 4 days after transplantation. Cotransplantation of PolyHb resulted in a dose-dependent reduction of beta-cell hypoxia, but beta-cell apoptosis was only reduced by cotransplantation of low-dose PolyHb (0.03 mg/g body weight) due to the inflammatory effects of higher PolyHb concentrations. Cotransplantation of low-dose PolyHb resulted in improved islet graft function 30 days after transplantation in diabetic mice, with a glucose tolerance comparable to transplantation of 50% more islets. Conclusion. We conclude that cotransplantation of islets with PolyHb can be used to effectively bridge the critical hypoxic phase immediately after transplantation, improve islet graft function, and reduce the number of islets needed for successful intramuscular transplantation.

National Category
Cell and Molecular Biology
Identifiers
urn:nbn:se:uu:diva-275353 (URN)10.1097/TP.0000000000000815 (DOI)000369086800016 ()26426924 (PubMedID)
Available from: 2016-02-10 Created: 2016-02-03 Last updated: 2017-11-30Bibliographically approved
2. Activation of Complement C3 Does NotHamper the Outcome of Experimental Intramuscular Islet Transplantation
Open this publication in new window or tab >>Activation of Complement C3 Does NotHamper the Outcome of Experimental Intramuscular Islet Transplantation
2016 (English)In: Transplantation, ISSN 0041-1337, E-ISSN 1534-6080, Vol. 100, no 3, E6-E7 p.Article in journal, Letter (Refereed) Published
Keyword
Islet transplantation, complement C3, alternative implantation sites
National Category
Cell and Molecular Biology
Research subject
Medical Cell Biology
Identifiers
urn:nbn:se:uu:diva-282949 (URN)10.1097/TP.0000000000001083 (DOI)000371582400001 ()26900812 (PubMedID)
Available from: 2016-04-08 Created: 2016-04-08 Last updated: 2017-11-30Bibliographically approved
3. Restoration of Islet Vascularity and Oxygenation in Mouse and Human Islets Experimentally Transplanted to the Omentum: A Basis for Superior Function when Compared to Intraportally Transplanted Islets
Open this publication in new window or tab >>Restoration of Islet Vascularity and Oxygenation in Mouse and Human Islets Experimentally Transplanted to the Omentum: A Basis for Superior Function when Compared to Intraportally Transplanted Islets
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2016 (English)In: American Journal of Transplantation, ISSN 1600-6135, E-ISSN 1600-6143Article in journal (Refereed) Submitted
Keyword
Islet transplantation, omentum, engraftment
National Category
Cell and Molecular Biology
Research subject
Medical Cell Biology
Identifiers
urn:nbn:se:uu:diva-282948 (URN)
Funder
Swedish Research Council, 55X-15043
Available from: 2016-04-08 Created: 2016-04-08 Last updated: 2017-08-22Bibliographically approved
4. Function and Gene Expression of Islets Experimentally Transplanted to Muscle or Omentum
Open this publication in new window or tab >>Function and Gene Expression of Islets Experimentally Transplanted to Muscle or Omentum
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(English)Manuscript (preprint) (Other academic)
Keyword
Islet transplantation, muscle, omentum, engraftment, gene expression, laser capture microdissection
National Category
Cell and Molecular Biology
Research subject
Medical Cell Biology
Identifiers
urn:nbn:se:uu:diva-282952 (URN)
Available from: 2016-04-08 Created: 2016-04-08 Last updated: 2016-06-01
5. Quantification of Beta-Cell Mass in Intramuscular Islet Grafts using Radiolabeled Exendin-4
Open this publication in new window or tab >>Quantification of Beta-Cell Mass in Intramuscular Islet Grafts using Radiolabeled Exendin-4
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2016 (English)In: Transplantation Direct, ISSN 2373-8731, Vol. 2, no 8, e93Article in journal (Refereed) Published
Abstract [en]

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.

Keyword
Islet transplantation, beta-cell mass, exendin-4, Lutetium-177
National Category
Cell and Molecular Biology
Research subject
Medical Cell Biology
Identifiers
urn:nbn:se:uu:diva-282942 (URN)10.1097/TXD.0000000000000598 (DOI)000390130200004 ()27819034 (PubMedID)
Funder
Swedish Research Council, 55X-15043
Available from: 2016-04-08 Created: 2016-04-08 Last updated: 2017-01-30Bibliographically approved
6. The Positron Emission Tomography ligand [11C]5-Hydroxy-Tryptophan can be used as a surrogate marker for the human endocrine pancreas
Open this publication in new window or tab >>The Positron Emission Tomography ligand [11C]5-Hydroxy-Tryptophan can be used as a surrogate marker for the human endocrine pancreas
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2014 (English)In: Diabetes, ISSN 0012-1797, E-ISSN 1939-327X, Vol. 63, no 10, 3428-3437 p.Article in journal (Refereed) Published
Abstract [en]

In humans a well-developed serotonin system is localized to the pancreatic islets while being absent in exocrine pancreas. Assessment of pancreatic serotonin biosynthesis could therefore be used to estimate the human endocrine pancreas. Proof of concept was tested in a prospective clinical trial by comparisons of type 1 diabetic (T1D) patients, with extensive reduction of beta cells, with healthy volunteers (HV).C-peptide negative (i.e. insulin-deficient) T1D subjects (n=10) and HV (n=9) underwent dynamic Positron Emission Tomography with the radiolabeled serotonin precursor [(11)C]5-Hydroxy-Tryptophan ([(11)C]5-HTP).A significant accumulation of [(11)C]5-HTP was obtained in the pancreas of the HV, with large inter-individual variation. A substantial and highly significant reduction (66%) in the pancreatic uptake of [(11)C]5-HTP in T1D subjects was observed, and this was most evident in the corpus and caudal regions of the pancreas where beta-cells normally are the major constituent of the islets.[(11)C]5-HTP retention in the pancreas was reduced in T1D compared to non-diabetic subjects. Accumulation of [(11)C]5-HTP in the pancreas of both HV and subjects with T1D were in agreement with previously reported morphological observations on the beta cell volume implying that [(11)C]5-HTP retention is a useful non-invasive surrogate marker for the human endocrine pancreas.

National Category
Other Basic Medicine
Identifiers
urn:nbn:se:uu:diva-224960 (URN)10.2337/db13-1877 (DOI)000342527300029 ()24848067 (PubMedID)
Available from: 2014-05-25 Created: 2014-05-25 Last updated: 2017-12-05Bibliographically approved

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