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BETA
Selvaraju, Ramkumar
Alternative names
Publications (10 of 48) Show all publications
Eriksson, J., Roy, T., Sawadjoon, S., Bachmann, K., Sköld, C., Larhed, M., . . . Odell, L. R. (2019). Synthesis and preclinical evaluation of the CRTH2 antagonist [11C]MK-7246 as a novel PET tracer and potential surrogate marker for pancreatic beta-cell mass. Nuclear Medicine and Biology, 71, 1-10
Open this publication in new window or tab >>Synthesis and preclinical evaluation of the CRTH2 antagonist [11C]MK-7246 as a novel PET tracer and potential surrogate marker for pancreatic beta-cell mass
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2019 (English)In: Nuclear Medicine and Biology, ISSN 0969-8051, E-ISSN 1872-9614, Vol. 71, p. 1-10Article in journal (Refereed) Published
Abstract [en]

Introduction: MK-7246 is a potent and selective antagonist for chemoattractant receptor-homologous molecule expressed on Th2 cells (CRTH2). Within the pancreas CRTH2 is selectively expressed in pancreatic β-cells where it is believed to play a role in insulin release. Reduction in β-cell mass and insufficient insulin secretion in response to elevated blood glucose levels is a hallmark for type 1 and type 2 diabetes. Reported here is the synthesis of [11C]MK-7246 and initial preclinical evaluation towards CRTH2 imaging. The aim is to develop a method to quantify β-cell mass with PET and facilitate non-invasive studies of disease progression in individuals with type 2 diabetes.

Methods: The precursor N-desmethyl-O-methyl MK-7246 was synthesized in seven steps and subjected to methylation with [11C]methyl iodide followed by hydrolysis to obtain [11C]MK-7246 labelled in the N-methyl position. Preclinical evaluation included in vitro radiography and immune-staining performed in human pancreatic biopsies. Biodistribution studies were performed in rat by PET-MRI and in pig by PET-CT imaging. The specific tracer uptake was examined in pig by scanning before and after administration of MK-7246 (1 mg/kg). Predicted dosimetry of [11C]MK-7246 in human males was estimated based on the biodistribution in rat.

Results: [11C]MK-7246 was obtained with activities sufficient for the current investigations (270±120 MBq) and a radiochemical purity of 93±2%. The tracer displayed focal binding in areas with insulin positive islet of Langerhans in human pancreas sections. Baseline uptake in pig was significantly reduced in CRTH2-rich areas after administration of MK-7246; pancreas (66% reduction) and spleen (88% reduction). [11C]MK-7246 exhibited a safe human predicted dosimetry profile as extrapolated from the rat biodistribution data.

Conclusions: Initial preclinical in vitro and in vivo evaluation of [11C]MK-7246 show binding and biodistribution properties suitable for PET imaging of CRTH2. Further studies are warranted to assess its potential in β-cell mass imaging and CRTH2 drug development.

National Category
Organic Chemistry Medicinal Chemistry
Identifiers
urn:nbn:se:uu:diva-381559 (URN)10.1016/j.nucmedbio.2019.04.002 (DOI)000475837000001 ()
Funder
Swedish Research Council, 2018-05133Knut and Alice Wallenberg FoundationSwedish Child Diabetes FoundationGöran Gustafsson Foundation for Research in Natural Sciences and Medicine
Available from: 2019-04-11 Created: 2019-04-11 Last updated: 2019-09-13Bibliographically approved
Eriksson, O., Johnström, P., Cselenyi, Z., Jahan, M., Selvaraju, R. k., Jensen-Waern, M., . . . Korsgren, O. (2018). In Vivo Visualization of beta-Cells by Targeting of GPR44. Diabetes, 67(2), 182-192
Open this publication in new window or tab >>In Vivo Visualization of beta-Cells by Targeting of GPR44
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2018 (English)In: Diabetes, ISSN 0012-1797, E-ISSN 1939-327X, Vol. 67, no 2, p. 182-192Article in journal (Refereed) Published
Abstract [en]

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.

National Category
Endocrinology and Diabetes
Identifiers
urn:nbn:se:uu:diva-342900 (URN)10.2337/db17-0764 (DOI)000426034500003 ()29208633 (PubMedID)
Funder
Swedish Research Council, K2015-54X-12219-19-4, K2013-64X-08268-26-3, K2013-55X-15043, 921-2014-7054Ernfors FoundationGöran Gustafsson Foundation for Research in Natural Sciences and MedicineSwedish Child Diabetes FoundationSwedish Diabetes AssociationEXODIAB - Excellence of Diabetes Research in Sweden
Available from: 2018-02-23 Created: 2018-02-23 Last updated: 2018-05-09Bibliographically approved
Hulsart Billström, G., Selvaraju, R., Estrada, S., Lubberink, M., Asplund, V., Bergman, K., . . . Antoni, G. (2018). Non-invasive tri-modal visualisation via PET/SPECT/μCT of recombinant human bone morphogenetic protein-2 retention and associated bone regeneration: A proof of concept. Journal of Controlled Release, 285, 178-186
Open this publication in new window or tab >>Non-invasive tri-modal visualisation via PET/SPECT/μCT of recombinant human bone morphogenetic protein-2 retention and associated bone regeneration: A proof of concept
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2018 (English)In: Journal of Controlled Release, ISSN 0168-3659, E-ISSN 1873-4995, Vol. 285, p. 178-186Article in journal (Refereed) Published
Abstract [en]

Bone morphogenetic proteins (BMP's) are vital for bone and cartilage formation, where bone morphogenetic protein-2 (BMP-2) is acknowledged as a growth factor in osteoblast differentiation. However, uncontrolled delivery may result in adverse clinical effects. In this study we investigated the possibility for longitudinal and non-invasive monitoring of implanted [125I]BMP-2 retention and its relation to ossification at the site of implantation. A unilateral critically sized femoral defect was produced in the left limb of rats while the right femur was retained intact as a paired reference control. The defect was filled with a hyaluronan hydrogel with 25% hydroxyapatite alone (carrier control; n = 2) or combined with a mixture of [125I]BMP-2 (150 μg/ml; n = 4). Bone formation was monitored using micro computed tomography (μCT) scans at 1, 3, 5, 7, 9 and 12 weeks. The retention of [125I]BMP-2 was assessed with single photon emission computed tomography (SPECT), and the bone healing process was followed with sodium fluoride (Na18F) using positron emission tomography (PET) at day 3 and at week 2, 4, and 6. A rapid burst release of [125I]BMP-2 was detected via SPECT. This was followed by a progressive increase in uptake levels of [18F]fluoride depicted by PET imaging that was confirmed as bone formation via μCT. We propose that this functional, non-invasive imaging method allows tri-modal visualisation of the release of BMP-2 and the following in vivo response. We suggest that the potential of this novel technique could be considered for preclinical evaluation of novel smart materials on bone regeneration.

Keywords
Bone morphogenetic protein 2, Bone tissue engineering, Hydrogel, Micro computed tomography, Positron emission tomography, Single-photon emission computed tomography
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:uu:diva-356465 (URN)10.1016/j.jconrel.2018.07.012 (DOI)000441737400015 ()30005906 (PubMedID)
Funder
EU, FP7, Seventh Framework Programme, 262948
Note

G. Hulsart-Billström and R. K. Selvaraju contributed equally to this work and should be regarded as joint first authors.

Available from: 2018-07-28 Created: 2018-07-28 Last updated: 2018-10-10Bibliographically approved
Eriksson, O., Korsgren, O., Selvaraju, R. K., Mollaret, M., de Boysson, Y., Chimienti, F. & Altai, M. (2018). Pancreatic imaging using an antibody fragment targeting the zinc transporter type 8: a direct comparison with radio-iodinated Exendin-4. Acta Diabetologica, 55(1), 49-57
Open this publication in new window or tab >>Pancreatic imaging using an antibody fragment targeting the zinc transporter type 8: a direct comparison with radio-iodinated Exendin-4
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2018 (English)In: Acta Diabetologica, ISSN 0940-5429, E-ISSN 1432-5233, Vol. 55, no 1, p. 49-57Article in journal (Refereed) Published
Abstract [en]

AIM: The zinc transporter 8 (ZnT8) has been suggested as a suitable target for non-invasive visualization of the functional pancreatic beta cell mass, due to both its pancreatic beta cell restricted expression and tight involvement in insulin secretion.

METHODS: In order to examine the potential of ZnT8 as a surrogate target for beta cell mass, we performed mRNA transcription analysis in pancreatic compartments. A novel ZnT8 targeting antibody fragment Ab31 was radiolabeled with iodine-125, and evaluated by in vitro autoradiography in insulinoma and pancreas as well as by in vivo biodistribution. The evaluation was performed in a direct comparison with radio-iodinated Exendin-4.

RESULTS: Transcription of the ZnT8 mRNA was higher in islets of Langerhans compared to exocrine tissue. Ab31 targeted ZnT8 in the cytosol and on the plasma membrane with 108 nM affinity. Ab31 was successfully radiolabeled with iodine-125 with high yield and > 95% purity. [(125)I]Ab31 binding to insulinoma and pancreas was higher than for [(125)I]Exendin-4, but could only by partially competed away by 200 nM Ab31 in excess. The in vivo uptake of [(125)I]Ab31 was higher than [(125)I]Exendin-4 in most tissues, mainly due to slower clearance from blood.

CONCLUSIONS: We report a first-in-class ZnT8 imaging ligand for pancreatic imaging. Development with respect to ligand miniaturization and radionuclide selection is required for further progress. Transcription analysis indicates ZnT8 as a suitable target for visualization of the human endocrine pancreas.

Place, publisher, year, edition, pages
Springer, 2018
Keywords
Ab31, Beta cell imaging, Imaging, Islet imaging, Type 2 diabetes, Zinc Transport type 8
National Category
Endocrinology and Diabetes
Identifiers
urn:nbn:se:uu:diva-334594 (URN)10.1007/s00592-017-1059-x (DOI)000424018600006 ()29064047 (PubMedID)
Funder
Swedish Child Diabetes FoundationErnfors Foundation
Available from: 2017-11-24 Created: 2017-11-24 Last updated: 2019-06-27Bibliographically approved
Mitran, B., Güler, R., Roche, F. P., Lindström, E., Selvaraju, R., Fleetwood, F., . . . Löfblom, J. (2018). Radionuclide imaging of VEGFR2 in glioma vasculature using biparatopic affibody conjugate: proof-of-principle in a murine model. Theranostics, 8(16), 4462-4476
Open this publication in new window or tab >>Radionuclide imaging of VEGFR2 in glioma vasculature using biparatopic affibody conjugate: proof-of-principle in a murine model
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2018 (English)In: Theranostics, ISSN 1838-7640, E-ISSN 1838-7640, Vol. 8, no 16, p. 4462-4476Article in journal (Refereed) Published
Abstract [en]

Vascular endothelial growth factor receptor-2 (VEGFR2) is a key mediator of angiogenesis and therefore a promising therapeutic target in malignancies including glioblastoma multiforme (GBM). Molecular imaging of VEGFR2 expression may enable patient stratification for antiangiogenic therapy. The goal of the current study was to evaluate the capacity of the novel anti-VEGFR2 biparatopic affibody conjugate (Z(VEGFR2)-Bp(2)) for in vivo visualization of VEGFR2 expression in GBM.

Methods: Z(VEGFR2)-Bp(2) coupled to a NODAGA chelator was generated and radiolabeled with indium-111. The VEGFR2-expressing murine endothelial cell line MS1 was used to evaluate in vitro binding specificity and affinity, cellular processing and targeting specificity in mice. Further tumor targeting was studied in vivo in GL261 glioblastoma orthotopic tumors. Experimental imaging was performed.

Results: [In-111]In-NODAGA-Z(VEGFR2)-Bp(2) bound specifically to VEGFR2 (K-D=33 +/- 18 pM). VEGFR2-mediated accumulation was observed in liver, spleen and lungs. The tumor-to-organ ratios 2 h post injection for mice bearing MS1 tumors were approximately 11 for blood, 15 for muscles and 78 for brain. Intracranial GL261 glioblastoma was visualized using SPECT/CT. The activity uptake in tumors was significantly higher than in normal brain tissue. The tumor-to-cerebellum ratios after injection of 4 mu g [In-111]In-NODAGA-Z(VEGFR2)-Bp(2) were significantly higher than the ratios observed for the 40 mu g injected dose and for the non-VEGFR2 binding size-matched conjugate, demonstrating target specificity. Microautoradiography of cryosectioned CNS tissue was in good agreement with the SPECT/CT images.

Conclusion: The anti-VEGFR2 affibody conjugate [In-111]In-NODAGA-Z(VEGFR2)-Bp(2) specifically targeted VEGFR2 in vivo and visualized its expression in a murine GBM orthotopic model. Tumor-to-blood ratios for [In-111]In-NODAGA-Z(VEGFR2)-Bp(2) were higher compared to other VEGFR2 imaging probes. [In-111]In-NODAGA-Z(VEGFR2)-Bp(2) appears to be a promising probe for in vivo noninvasive visualization of tumor angiogenesis in glioblastoma.

Place, publisher, year, edition, pages
IVYSPRING INT PUBL, 2018
Keywords
VEGFR2, affibody molecule, molecular imaging, SPECT, orthotopic glioma model, in vivo
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:uu:diva-365854 (URN)10.7150/thno.24395 (DOI)000444104300013 ()30214632 (PubMedID)
Funder
Knut and Alice Wallenberg FoundationSwedish Research Council, 621-2012-5236Swedish Research Council, 2015-02509Swedish Research Council, 2015-02353VINNOVA, 2016-04060VINNOVA, 2017-02015Science for Life Laboratory - a national resource center for high-throughput molecular bioscienceSwedish Cancer Society, CAN2017/649Swedish Cancer Society, CAN2013/586Swedish Cancer Society, CAN2016/463Swedish Cancer Society, CAN2014/474Swedish Cancer Society, CAN2017/425Swedish Cancer Society, CAN2015/350Swedish Cancer Society, CAN2016/585
Note

De två första författarna delar förstaförfattarskapet.

De två sista författarna delar sistaförfattarskapet

Available from: 2018-11-15 Created: 2018-11-15 Last updated: 2018-11-15Bibliographically approved
Jahan, M., Johnström, P., Selvaraju, R., Svedberg, M., Winzell, M. S., Bernström, J., . . . Eriksson, O. (2018). The development of a GPR44 targeting radioligand [11C]AZ12204657 for in vivo assessment of beta cell mass.. EJNMMI Research, 8, Article ID 113.
Open this publication in new window or tab >>The development of a GPR44 targeting radioligand [11C]AZ12204657 for in vivo assessment of beta cell mass.
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2018 (English)In: EJNMMI Research, ISSN 2191-219X, E-ISSN 2191-219X, Vol. 8, article id 113Article in journal (Refereed) Published
Abstract [en]

BACKGROUND: The G-protein-coupled receptor 44 (GPR44) is a beta cell-restricted target that may serve as a marker for beta cell mass (BCM) given the development of a suitable PET ligand.

METHODS: The binding characteristics of the selected candidate, AZ12204657, at human GPR44 were determined using in vitro ligand binding assays. AZ12204657 was radiolabeled using 11C- or 3H-labeled methyl iodide ([11C/3H]CH3I) in one step, and the conversion of [11C/3H]CH3I to the radiolabeled product [11C/3H]AZ12204657 was quantitative. The specificity of radioligand binding to GPR44 and the selectivity for beta cells were evaluated by in vitro binding studies on pancreatic sections from human and non-human primates as well as on homogenates from endocrine and exocrine pancreatic compartments.

RESULTS: The radiochemical purity of the resulting radioligand [11C]AZ12204657 was > 98%, with high molar activity (MA), 1351 ± 575 GBq/μmol (n = 18). The radiochemical purity of [3H]AZ12204657 was > 99% with MA of 2 GBq/μmol. Pancreatic binding of [11C/3H]AZ12204657 was co-localized with insulin-positive islets of Langerhans in non-diabetic individuals and individuals with type 2 diabetes (T2D). The binding of [11C]AZ12204657 to GPR44 was > 10 times higher in islet homogenates compared to exocrine homogenates. In human islets of Langerhans GPR44 was co-expressed with insulin, but not glucagon as assessed by co-staining and confocal microscopy.

CONCLUSION: We radiolabeled [11C]AZ12204657, a potential PET radioligand for the beta cell-restricted protein GPR44. In vitro evaluation demonstrated that [3H]AZ12204657 and [11C]AZ12204657 selectively target pancreatic beta cells. [11C]AZ12204657 has promising properties as a marker for human BCM.

Keywords
Beta cell imaging, Beta cell mass, Diabetes, G-protein-coupled receptor 44 (GPR44), Islet imaging
National Category
Endocrinology and Diabetes
Identifiers
urn:nbn:se:uu:diva-373205 (URN)10.1186/s13550-018-0465-6 (DOI)000454413500002 ()30588560 (PubMedID)
Funder
Science for Life Laboratory - a national resource center for high-throughput molecular bioscienceSwedish Diabetes AssociationNovo NordiskSwedish Child Diabetes FoundationEXODIAB - Excellence of Diabetes Research in Sweden
Available from: 2019-01-11 Created: 2019-01-11 Last updated: 2019-01-16Bibliographically approved
Mitran, B., Guler, R., Roche, F. P., Lindström, E., Selvaraju, R., Heetwood, F., . . . Löfblom, J. (2017). Novel high affinity affibody for radionuclide imaging of VEGFR2 in glioma vasculature: proof-of-principle in murine model. European Journal of Nuclear Medicine and Molecular Imaging, 44, S239-S239
Open this publication in new window or tab >>Novel high affinity affibody for radionuclide imaging of VEGFR2 in glioma vasculature: proof-of-principle in murine model
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2017 (English)In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 44, p. S239-S239Article in journal, Meeting abstract (Other academic) Published
Place, publisher, year, edition, pages
Springer, 2017
National Category
Radiology, Nuclear Medicine and Medical Imaging
Identifiers
urn:nbn:se:uu:diva-377080 (URN)000455019400225 ()
Available from: 2019-02-21 Created: 2019-02-21 Last updated: 2019-02-21Bibliographically approved
Eriksson, O., Rosenström, U., Selvaraju, R. K., Eriksson, B. & Velikyan, I. (2017). Species differences in pancreatic binding of DO3A-VS-Cys40-Exendin4. Acta Diabetologica, 54(11), 1039-1045
Open this publication in new window or tab >>Species differences in pancreatic binding of DO3A-VS-Cys40-Exendin4
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2017 (English)In: Acta Diabetologica, ISSN 0940-5429, E-ISSN 1432-5233, Vol. 54, no 11, p. 1039-1045Article in journal (Refereed) Published
Abstract [en]

AIMS: Radiolabeled Exendin-4 has been proposed as suitable imaging marker for pancreatic beta cell mass quantification mediated by Glucagon-like peptide-1 receptor (GLP-1R). However, noticeable species variations in basal pancreatic uptake as well as uptake reduction degree due to selective beta cell ablation were observed.

METHODS: -Exendin4 Positron Emission Tomography (PET) in the same species. In vitro, ex vivo, and in vivo data formed the basis for calculating the theoretical in vivo contribution of each pancreatic compartment.

RESULTS: -Exendin4.

CONCLUSIONS: IPR as well as the exocrine GLP-1R density is the main determinants of the species variability in pancreatic uptake. Thus, the IPR in human is an important factor for assessing the potential of GLP-1R as an imaging biomarker for pancreatic beta cells.

Keywords
Animal models, Beta cell imaging, Beta cell mass, Exendin4, GLP-1R, Positron emission tomography
National Category
Endocrinology and Diabetes
Identifiers
urn:nbn:se:uu:diva-342527 (URN)10.1007/s00592-017-1046-2 (DOI)000413142300008 ()28891030 (PubMedID)
Available from: 2018-02-21 Created: 2018-02-21 Last updated: 2018-02-23Bibliographically approved
Spiegelberg, D., Mortensen, A. C., Selvaraju, R. K., Eriksson, O., Stenerlöw, B. & Nestor, M. (2016). Molecular imaging of EGFR and CD44v6 for prediction and response monitoring of HSP90 inhibition in an in vivo squamous cell carcinoma model.. European Journal of Nuclear Medicine and Molecular Imaging, 43(5), 974-982
Open this publication in new window or tab >>Molecular imaging of EGFR and CD44v6 for prediction and response monitoring of HSP90 inhibition in an in vivo squamous cell carcinoma model.
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2016 (English)In: European Journal of Nuclear Medicine and Molecular Imaging, ISSN 1619-7070, E-ISSN 1619-7089, Vol. 43, no 5, p. 974-982Article in journal (Refereed) Published
Abstract [en]

PURPOSE: Heat shock protein 90 (HSP90) is essential for the activation and stabilization of numerous oncogenic client proteins. AT13387 is a novel HSP90 inhibitor promoting degradation of oncogenic proteins upon binding, and may also act as a radiosensitizer. For optimal treatment there is, however, the need for identification of biomarkers for patient stratification and therapeutic response monitoring, and to find suitable targets for combination treatments. The aim of this study was to assess the response of surface antigens commonly expressed in squamous cell carcinoma to AT13387 treatment, and to find suitable biomarkers for molecular imaging and radioimmunotherapy in combination with HSP90 inhibition.

METHODS: Cancer cell proliferation and radioimmunoassays were used to evaluate the effect of AT13387 on target antigen expression in vitro. Inhibitor effects were then assessed in vivo in mice-xenografts. Animals were treated with AT13387 (5 × 50 mg/kg), and were imaged with PET using either (18)F-FDG or (124)I-labelled tracers for EGFR and CD44v6, and this was followed by ex-vivo biodistribution analysis and immunohistochemical staining.

RESULTS: AT13387 exposure resulted in high cytotoxicity and possible radiosensitization with IC50 values below 4 nM. Both in vitro and in vivo AT13387 effectively downregulated HSP90 client proteins. PET imaging with (124)I-cetuximab showed a significant decrease of EGFR in AT13387-treated animals compared with untreated animals. In contrast, the squamous cell carcinoma-associated biomarker CD44v6, visualized with (124)I-AbD19384 as well as (18)F-FDG uptake, were not significantly altered by AT13387 treatment.

CONCLUSION: We conclude that AT13387 downregulates HSP90 client proteins, and that molecular imaging of these proteins may be a suitable approach for assessing treatment response. Furthermore, radioimmunotherapy targeting CD44v6 in combination with AT13387 may potentiate the radioimmunotherapy outcome due to radiosensitizing effects of the drug, and could potentially lead to a lower dose to normal tissues.

National Category
Cancer and Oncology
Identifiers
urn:nbn:se:uu:diva-270260 (URN)10.1007/s00259-015-3260-x (DOI)000373306800020 ()26627081 (PubMedID)
Funder
Swedish Cancer Society, CAN 2012/399; CAN 2014/661Swedish Research Council, 2013-30876-104113-30
Available from: 2015-12-22 Created: 2015-12-22 Last updated: 2018-02-18Bibliographically approved
Espes, D., Selvaraju, R., Velikyan, I., Krajcovic, M., Carlsson, P.-O. & Eriksson, O. (2016). Quantification of Beta-Cell Mass in Intramuscular Islet Grafts using Radiolabeled Exendin-4. Transplantation Direct, 2(8), Article ID e93.
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, article id 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.

Keywords
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: 2018-01-10Bibliographically approved
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