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Tinklepaugh J, Mamrak NE. Imaging in Type 1 Diabetes, Current Perspectives and Directions. Mol Imaging Biol 2023; 25:1142-1149. [PMID: 37934378 DOI: 10.1007/s11307-023-01873-y] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 10/12/2023] [Accepted: 10/30/2023] [Indexed: 11/08/2023]
Abstract
Type 1 diabetes (T1D) is characterized by the autoimmune-mediated attack of insulin-producing beta cells in the pancreas, leading to reliance on exogenous insulin to control a patient's blood glucose levels. As progress is being made in understanding the pathophysiology of the disease and how to better develop therapies to treat it, there is an increasing need for monitoring technologies to quantify beta cell mass and function throughout T1D progression and beta cell replacement therapy. Molecular imaging techniques offer a possible solution through both radiologic and non-radiologic means including positron emission tomography, magnetic resonance imaging, electron paramagnetic resonance imaging, and spatial omics. This commentary piece outlines the role of molecular imaging in T1D research and highlights the need for further applications of such methodologies in T1D.
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Affiliation(s)
- Jay Tinklepaugh
- Research Department, JDRF, 200 Vesey Street, New York, NY, USA
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2
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Joshi SS, Singh T, Kershaw LE, Gibb FW, Dweck MR, Williams M, Idris I, Semple S, Forbes S, Newby DE, Reynolds RM. Non-invasive imaging of functional pancreatic islet beta-cell mass in people with type 1 diabetes mellitus. Diabet Med 2023; 40:e15111. [PMID: 37035965 PMCID: PMC10946460 DOI: 10.1111/dme.15111] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/02/2022] [Revised: 03/07/2023] [Accepted: 04/06/2023] [Indexed: 04/11/2023]
Abstract
AIMS To investigate whether manganese-enhanced magnetic resonance imaging can assess functional pancreatic beta-cell mass in people with type 1 diabetes mellitus. METHODS In a prospective case-control study, 20 people with type 1 diabetes mellitus (10 with low (≥50 pmol/L) and 10 with very low (<50 pmol/L) C-peptide concentrations) and 15 healthy volunteers underwent manganese-enhanced magnetic resonance imaging of the pancreas following an oral glucose load. Scan-rescan reproducibility was performed in 10 participants. RESULTS Mean pancreatic manganese uptake was 31 ± 6 mL/100 g of tissue/min in healthy volunteers (median 32 [interquartile range 23-36] years, 6 women), falling to 23 ± 4 and 13 ± 5 mL/100 g of tissue/min (p ≤ 0.002 for both) in people with type1 diabetes mellitus (52 [44-61] years, 6 women) and low or very low plasma C-peptide concentrations respectively. Pancreatic manganese uptake correlated strongly with plasma C-peptide concentrations in people with type1 diabetes mellitus (r = 0.73, p < 0.001) but not in healthy volunteers (r = -0.054, p = 0.880). There were no statistically significant correlations between manganese uptake and age, body-mass index, or glycated haemoglobin. There was strong intra-observer (mean difference: 0.31 (limits of agreement -1.42 to 2.05) mL/100 g of tissue/min; intra-class correlation, ICC = 0.99), inter-observer (-1.23 (-5.74 to 3.27) mL/100 g of tissue/min; ICC = 0.85) and scan-rescan (-0.72 (-2.9 to 1.6) mL/100 g of tissue/min; ICC = 0.96) agreement for pancreatic manganese uptake. CONCLUSIONS Manganese-enhanced magnetic resonance imaging provides a potential reproducible non-invasive measure of functional beta-cell mass in people with type 1 diabetes mellitus. This holds major promise for investigating type 1 diabetes, monitoring disease progression and assessing novel immunomodulatory interventions.
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Affiliation(s)
- Shruti S. Joshi
- British Heart Foundation Centre for Cardiovascular ScienceUniversity of EdinburghEdinburghUK
| | - Trisha Singh
- British Heart Foundation Centre for Cardiovascular ScienceUniversity of EdinburghEdinburghUK
| | - Lucy E. Kershaw
- British Heart Foundation Centre for Cardiovascular ScienceUniversity of EdinburghEdinburghUK
- Edinburgh ImagingUniversity of EdinburghEdinburghUK
| | - Fraser W. Gibb
- British Heart Foundation Centre for Cardiovascular ScienceUniversity of EdinburghEdinburghUK
- Edinburgh Centre for EndocrinologyNHS LothianEdinburghUK
| | - Marc R. Dweck
- British Heart Foundation Centre for Cardiovascular ScienceUniversity of EdinburghEdinburghUK
| | - Michelle Williams
- British Heart Foundation Centre for Cardiovascular ScienceUniversity of EdinburghEdinburghUK
- Edinburgh ImagingUniversity of EdinburghEdinburghUK
- Department of RadiologyNHS LothianEdinburghUK
| | - Iskandar Idris
- Department of EndocrinologyUniversity of NottinghamNottinghamUK
| | - Scott Semple
- British Heart Foundation Centre for Cardiovascular ScienceUniversity of EdinburghEdinburghUK
- Edinburgh ImagingUniversity of EdinburghEdinburghUK
| | - Shareen Forbes
- British Heart Foundation Centre for Cardiovascular ScienceUniversity of EdinburghEdinburghUK
- Edinburgh Centre for EndocrinologyNHS LothianEdinburghUK
| | - David E. Newby
- British Heart Foundation Centre for Cardiovascular ScienceUniversity of EdinburghEdinburghUK
- Edinburgh ImagingUniversity of EdinburghEdinburghUK
| | - Rebecca M. Reynolds
- British Heart Foundation Centre for Cardiovascular ScienceUniversity of EdinburghEdinburghUK
- Edinburgh Centre for EndocrinologyNHS LothianEdinburghUK
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Behzadifar S, Barras A, Plaisance V, Pawlowski V, Szunerits S, Abderrahmani A, Boukherroub R. Polymer-Based Nanostructures for Pancreatic Beta-Cell Imaging and Non-Invasive Treatment of Diabetes. Pharmaceutics 2023; 15:pharmaceutics15041215. [PMID: 37111699 PMCID: PMC10143373 DOI: 10.3390/pharmaceutics15041215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 04/01/2023] [Accepted: 04/07/2023] [Indexed: 04/29/2023] Open
Abstract
Diabetes poses major economic, social, and public health challenges in all countries worldwide. Besides cardiovascular disease and microangiopathy, diabetes is a leading cause of foot ulcers and lower limb amputations. With the continued rise of diabetes prevalence, it is expected that the future burden of diabetes complications, early mortality, and disabilities will increase. The diabetes epidemic is partly caused by the current lack of clinical imaging diagnostic tools, the timely monitoring of insulin secretion and insulin-expressing cell mass (beta (β)-cells), and the lack of patients' adherence to treatment, because some drugs are not tolerated or invasively administrated. In addition to this, there is a lack of efficient topical treatment capable of stopping the progression of disabilities, in particular for treating foot ulcers. In this context, polymer-based nanostructures garnered significant interest due to their tunable physicochemical characteristics, rich diversity, and biocompatibility. This review article emphasizes the last advances and discusses the prospects in the use of polymeric materials as nanocarriers for β-cell imaging and non-invasive drug delivery of insulin and antidiabetic drugs in the management of blood glucose and foot ulcers.
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Affiliation(s)
- Shakila Behzadifar
- Univ. Lille, CNRS, Centrale Lille, Univ. Polytechnique Hauts-de-France, UMR 8520, IEMN, F-59000 Lille, France
| | - Alexandre Barras
- Univ. Lille, CNRS, Centrale Lille, Univ. Polytechnique Hauts-de-France, UMR 8520, IEMN, F-59000 Lille, France
| | - Valérie Plaisance
- Univ. Lille, CNRS, Centrale Lille, Univ. Polytechnique Hauts-de-France, UMR 8520, IEMN, F-59000 Lille, France
| | - Valérie Pawlowski
- Univ. Lille, CNRS, Centrale Lille, Univ. Polytechnique Hauts-de-France, UMR 8520, IEMN, F-59000 Lille, France
| | - Sabine Szunerits
- Univ. Lille, CNRS, Centrale Lille, Univ. Polytechnique Hauts-de-France, UMR 8520, IEMN, F-59000 Lille, France
| | - Amar Abderrahmani
- Univ. Lille, CNRS, Centrale Lille, Univ. Polytechnique Hauts-de-France, UMR 8520, IEMN, F-59000 Lille, France
| | - Rabah Boukherroub
- Univ. Lille, CNRS, Centrale Lille, Univ. Polytechnique Hauts-de-France, UMR 8520, IEMN, F-59000 Lille, France
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4
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Puskar A, Saadah B, Rauf A, Kasperek SR, Umair M. A primer on contrast agents for magnetic resonance imaging of post‐procedural and follow‐up imaging of islet cell transplant. NANO SELECT 2023. [DOI: 10.1002/nano.202200147] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/10/2023] Open
Affiliation(s)
- Anessa Puskar
- Carle Illinois College of Medicine Urbana‐Champaign Urbana Illinois USA
| | - Bara Saadah
- Carle Illinois College of Medicine Urbana‐Champaign Urbana Illinois USA
| | - Asad Rauf
- Carle Illinois College of Medicine Urbana‐Champaign Urbana Illinois USA
| | | | - Muhammad Umair
- Department of Radiology Johns Hopkins Baltimore Maryland USA
- Department of Biomedical Engineering University of Illinois Urbana‐Champaign Urbana Illinois USA
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5
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Doherty D, Khambalia H, Summers A, Moinuddin Z, Yiannoullou P, Krishnan A, Augustine T, Naish J, van Dellen D. Future imaging modalities for the assessment of pancreas allografts a scan of the horizon. Transplant Rev (Orlando) 2022; 36:100692. [DOI: 10.1016/j.trre.2022.100692] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Revised: 03/22/2022] [Accepted: 03/23/2022] [Indexed: 10/18/2022]
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Zeng N, Wang Y, Cheng Y, Huang Z, Song B. Imaging evaluation of the pancreas in diabetic patients. Abdom Radiol (NY) 2022; 47:715-726. [PMID: 34786594 DOI: 10.1007/s00261-021-03340-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Revised: 10/28/2021] [Accepted: 10/29/2021] [Indexed: 02/05/2023]
Abstract
Diabetes mellitus (DM) is becoming a global epidemic and its diagnosis and monitoring are based on laboratory testing which sometimes have limitations. The pancreas plays a key role in metabolism and is involved in the pathogenesis of DM. It has long been known through cadaver biopsies that pancreas volume is decreased in patients with DM. With the development of different imaging modalities over the last two decades, many studies have attempted to determine whether there other changes occurred in the pancreas of diabetic patients. This review summarizes current knowledge about the use of different imaging approaches (such as CT, MR, and US) and radiomics for exploring pancreatic changes in diabetic patients. Imaging studies are expected to produce reliable information regarding DM, and radiomics could provide increasingly valuable information to identify some undetectable features and help diagnose and predict the occurrence of diabetes through pancreas imaging.
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Affiliation(s)
- Ni Zeng
- Department of Radiology, West China Hospital, Sichuan University, No. 37 Guoxue Alley, Chengdu, 610041, Sichuan, China
| | - Yi Wang
- Department of Radiology, West China Hospital, Sichuan University, No. 37 Guoxue Alley, Chengdu, 610041, Sichuan, China
| | - Yue Cheng
- Department of Radiology, West China Hospital, Sichuan University, No. 37 Guoxue Alley, Chengdu, 610041, Sichuan, China
| | - Zixing Huang
- Department of Radiology, West China Hospital, Sichuan University, No. 37 Guoxue Alley, Chengdu, 610041, Sichuan, China.
| | - Bin Song
- Department of Radiology, West China Hospital, Sichuan University, No. 37 Guoxue Alley, Chengdu, 610041, Sichuan, China.
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7
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Neo CWY, Ciaramicoli LM, Soetedjo AAP, Teo AKK, Kang NY. A new perspective of probe development for imaging pancreatic beta cell in vivo. Semin Cell Dev Biol 2020; 103:3-13. [PMID: 32057664 DOI: 10.1016/j.semcdb.2020.01.009] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Revised: 01/20/2020] [Accepted: 01/28/2020] [Indexed: 12/23/2022]
Abstract
Beta cells assume a fundamental role in maintaining blood glucose homeostasis through the secretion of insulin, which is contingent on both beta cell mass and function, in response to elevated blood glucose levels or secretagogues. For this reason, evaluating beta cell mass and function, as well as scrutinizing how they change over time in a diabetic state, are essential prerequisites in elucidating diabetes pathophysiology. Current clinical methods to measure human beta cell mass and/or function are largely lacking, indirect and sub-optimal, highlighting the continued need for noninvasive in vivo beta cell imaging technologies such as optical imaging techniques. While numerous probes have been developed and evaluated for their specificity to beta cells, most of them are more suited to visualize beta cell mass rather than function. In this review, we highlight the distinction between beta cell mass and function, and the importance of developing more probes to measure beta cell function. Additionally, we also explore various existing probes that can be employed to measure beta cell mass and function in vivo, as well as the caveats in probe development for in vivo beta cell imaging.
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Affiliation(s)
- Claire Wen Ying Neo
- Stem Cells and Diabetes Laboratory, Institute of Molecular and Cell Biology (IMCB), A*STAR, Singapore, 138673, Singapore; Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117596, Singapore
| | - Larissa Miasiro Ciaramicoli
- Department of Advanced Materials Science, Pohang University of Science and Technology (POSTECH), Pohang, 37673, Republic of Korea
| | - Andreas Alvin Purnomo Soetedjo
- Stem Cells and Diabetes Laboratory, Institute of Molecular and Cell Biology (IMCB), A*STAR, Singapore, 138673, Singapore
| | - Adrian Kee Keong Teo
- Stem Cells and Diabetes Laboratory, Institute of Molecular and Cell Biology (IMCB), A*STAR, Singapore, 138673, Singapore; Yong Loo Lin School of Medicine, National University of Singapore, Singapore, 117596, Singapore.
| | - Nam-Young Kang
- Department of Creative IT Engineering, Pohang University of Science and Technology (POSTECH), 77 Cheongam-ro, Namgu, C5 Building, Room 203, Pohang, Kyungbuk, 37673, Republic of Korea.
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8
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Kang NY, Soetedjo AAP, Amirruddin NS, Chang YT, Eriksson O, Teo AKK. Tools for Bioimaging Pancreatic β Cells in Diabetes. Trends Mol Med 2019; 25:708-722. [PMID: 31178230 DOI: 10.1016/j.molmed.2019.05.004] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2019] [Revised: 05/07/2019] [Accepted: 05/10/2019] [Indexed: 12/18/2022]
Abstract
When diabetes is diagnosed, the majority of insulin-secreting pancreatic β cells are already dysfunctional or destroyed. This β cell dysfunction/destruction usually takes place over many years, making timely detection and clinical intervention difficult. For this reason, there is immense interest in developing tools to bioimage β cell mass and/or function noninvasively to facilitate early diagnosis of diabetes as well as to assist the development of novel antidiabetic therapies. Recent years have brought significant progress in β cell imaging that is now inching towards clinical applicability. We explore here the need to bioimage human β cells noninvasively in various types of diabetes, and we discuss current and emerging tools for bioimaging β cells. Further developments in this field are expected to facilitate β cell imaging in diabetes.
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Affiliation(s)
- Nam-Young Kang
- Laboratory of Bioimaging Probe Development, Singapore Bioimaging Consortium, Agency for Science, Technology, and Research, 11 Biopolis Way, 02-02 Helios, 138667, Singapore; New Drug Development Center, Daegu Gyeongbuk Medical Innovation Foundation (DGMIF), 80 Chembok-ro (1115-1 Dongnae-dong), Dong-gu, Daegu City 41061, Republic of Korea.
| | | | - Nur Shabrina Amirruddin
- Stem Cells and Diabetes Laboratory, Institute of Molecular and Cell Biology, Proteos, 138673, Singapore; Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, 119228, Singapore
| | - Young-Tae Chang
- Laboratory of Bioimaging Probe Development, Singapore Bioimaging Consortium, Agency for Science, Technology, and Research, 11 Biopolis Way, 02-02 Helios, 138667, Singapore; Department of Chemistry, Pohang University of Science and Technology (POSTECH), Pohang, Gyeongbuk 37673, Republic of Korea; Center for Self-assembly and Complexity, Institute for Basic Science (IBS), 77 Hyogok-dong, Nam-gu, Pohang 37673, Republic of Korea
| | - Olof Eriksson
- Science for Life Laboratory, Department of Medicinal Chemistry, Uppsala University, Uppsala SE-752 36, Sweden
| | - Adrian Kee Keong Teo
- Stem Cells and Diabetes Laboratory, Institute of Molecular and Cell Biology, Proteos, 138673, Singapore; Department of Medicine, Yong Loo Lin School of Medicine, National University of Singapore, 119228, Singapore; Department of Biochemistry, Yong Loo Lin School of Medicine, National University of Singapore, 117596, Singapore; School of Biological Sciences, Nanyang Technological University, 637551, Singapore.
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9
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Saar G, Millo CM, Szajek LP, Bacon J, Herscovitch P, Koretsky AP. Anatomy, Functionality, and Neuronal Connectivity with Manganese Radiotracers for Positron Emission Tomography. Mol Imaging Biol 2019; 20:562-574. [PMID: 29396750 DOI: 10.1007/s11307-018-1162-6] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022]
Abstract
PURPOSE Manganese ion has been extensively used as a magnetic resonance imaging (MRI) contrast agent in preclinical studies to assess tissue anatomy, function, and neuronal connectivity. Unfortunately, its use in human studies has been limited by cellular toxicity and the need to use a very low dose. The much higher sensitivity of positron emission tomography (PET) over MRI enables the use of lower concentrations of manganese, potentially expanding the methodology to humans. PROCEDURES PET tracers manganese-51 (Mn-51, t1/2 = 46 min) and manganese-52 (Mn-52, t1/2 = 5.6 days) were used in this study. The biodistribution of manganese in animals in the brain and other tissues was studied as well as the uptake in the pancreas after glucose stimulation as a functional assay. Finally, neuronal connectivity in the olfactory pathway following nasal administration of the divalent radioactive Mn-52 ([52Mn]Mn2+) was imaged. RESULTS PET imaging with the divalent radioactive Mn-51 ([51Mn]Mn2+) and [52Mn]Mn2+ in both rodents and monkeys demonstrates that the accumulation of activity in different organs is similar to that observed in rodent MRI studies following systemic administration. Furthermore, we demonstrated the ability of manganese to enter excitable cells. We followed activity-induced [51Mn]Mn2+ accumulation in the pancreas after glucose stimulation and showed that [52Mn]Mn2+ can be used to trace neuronal connections analogous to manganese-enhanced MRI neuronal tracing studies. CONCLUSIONS The results were consistent with manganese-enhanced MRI studies, despite the much lower manganese concentration used for PET (100 mM Mn2+ for MRI compared to ~ 0.05 mM for PET). This indicates that uptake and transport mechanisms are comparable even at low PET doses. This helps establish the use of manganese-based radiotracers in both preclinical and clinical studies to assess anatomy, function, and connectivity.
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Affiliation(s)
- Galit Saar
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Corina M Millo
- PET Department, Clinical Center, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Lawrence P Szajek
- PET Department, Clinical Center, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Jeff Bacon
- PET Department, Clinical Center, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Peter Herscovitch
- PET Department, Clinical Center, National Institutes of Health, Bethesda, MD, 20892, USA
| | - Alan P Koretsky
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD, 20892, USA.
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10
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Wei W, Ehlerding EB, Lan X, Luo QY, Cai W. Molecular imaging of β-cells: diabetes and beyond. Adv Drug Deliv Rev 2019; 139:16-31. [PMID: 31378283 DOI: 10.1016/j.addr.2018.06.022] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Revised: 04/27/2018] [Accepted: 06/26/2018] [Indexed: 02/09/2023]
Abstract
Since diabetes is becoming a global epidemic, there is a great need to develop early β-cell specific diagnostic techniques for this disorder. There are two types of diabetes (i.e., type 1 diabetes mellitus (T1DM) and type 2 diabetes mellitus (T2DM)). In T1DM, the destruction of pancreatic β-cells leads to reduced insulin production or even absolute insulin deficiency, which consequently results in hyperglycemia. Actually, a central issue in the pathophysiology of all types of diabetes is the relative reduction of β-cell mass (BCM) and/or impairment of the function of individual β-cells. In the past two decades, scientists have been trying to develop imaging techniques for noninvasive measurement of the viability and mass of pancreatic β-cells. Despite intense scientific efforts, only two tracers for positron emission tomography (PET) and one contrast agent for magnetic resonance (MR) imaging are currently under clinical evaluation. β-cell specific imaging probes may also allow us to precisely and specifically visualize transplanted β-cells and to improve transplantation outcomes, as transplantation of pancreatic islets has shown promise in treating T1DM. In addition, some of these probes can be applied to the preoperative detection of hidden insulinomas as well. In the present review, we primarily summarize potential tracers under development for imaging β-cells with a focus on tracers for PET, SPECT, MRI, and optical imaging. We will discuss the advantages and limitations of the various imaging probes and extend an outlook on future developments in the field.
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Hernandez R, Graves SA, Gregg T, VanDeusen HR, Fenske RJ, Wienkes HN, England CG, Valdovinos HF, Jeffery JJ, Barnhart TE, Severin GW, Nickles RJ, Kimple ME, Merrins MJ, Cai W. Radiomanganese PET Detects Changes in Functional β-Cell Mass in Mouse Models of Diabetes. Diabetes 2017; 66:2163-2174. [PMID: 28515126 PMCID: PMC5521871 DOI: 10.2337/db16-1285] [Citation(s) in RCA: 31] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/24/2016] [Accepted: 05/12/2017] [Indexed: 01/09/2023]
Abstract
The noninvasive measurement of functional β-cell mass would be clinically valuable for monitoring the progression of type 1 and type 2 diabetes as well as the viability of transplanted insulin-producing cells. Although previous work using MRI has shown promise for functional β-cell mass determination through voltage-dependent Ca2+ channel (VDCC)-mediated internalization of Mn2+, the clinical utility of this technique is limited by the cytotoxic levels of the Mn2+ contrast agent. Here, we show that positron emission tomography (PET) is advantageous for determining functional β-cell mass using 52Mn2+ (t1/2: 5.6 days). We investigated the whole-body distribution of 52Mn2+ in healthy adult mice by dynamic and static PET imaging. Pancreatic VDCC uptake of 52Mn2+ was successfully manipulated pharmacologically in vitro and in vivo using glucose, nifedipine (VDCC blocker), the sulfonylureas tolbutamide and glibenclamide (KATP channel blockers), and diazoxide (KATP channel opener). In a mouse model of streptozotocin-induced type 1 diabetes, 52Mn2+ uptake in the pancreas was distinguished from healthy controls in parallel with classic histological quantification of β-cell mass from pancreatic sections. 52Mn2+-PET also reported the expected increase in functional β-cell mass in the ob/ob model of pretype 2 diabetes, a result corroborated by histological β-cell mass measurements and live-cell imaging of β-cell Ca2+ oscillations. These results indicate that 52Mn2+-PET is a sensitive new tool for the noninvasive assessment of functional β-cell mass.
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Affiliation(s)
- Reinier Hernandez
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI
| | - Stephen A Graves
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI
| | - Trillian Gregg
- Department of Medicine, Division of Endocrinology, Diabetes & Metabolism, University of Wisconsin-Madison, Madison, WI
- Program in Biophysics, University of Wisconsin-Madison, Madison, WI
| | - Halena R VanDeusen
- Department of Medicine, Division of Endocrinology, Diabetes & Metabolism, University of Wisconsin-Madison, Madison, WI
| | - Rachel J Fenske
- Department of Medicine, Division of Endocrinology, Diabetes & Metabolism, University of Wisconsin-Madison, Madison, WI
| | - Haley N Wienkes
- Department of Medicine, Division of Endocrinology, Diabetes & Metabolism, University of Wisconsin-Madison, Madison, WI
| | | | | | - Justin J Jeffery
- Carbone Cancer Center, University of Wisconsin-Madison, Madison, WI
| | - Todd E Barnhart
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI
| | - Gregory W Severin
- Center for Nuclear Technologies, Technical University of Denmark, Roskilde, Denmark
- Department of Chemistry, Michigan State University, East Lansing, MI
| | - Robert J Nickles
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI
| | - Michelle E Kimple
- Department of Medicine, Division of Endocrinology, Diabetes & Metabolism, University of Wisconsin-Madison, Madison, WI
- William S. Middleton Memorial Veterans Hospital, Madison, WI
| | - Matthew J Merrins
- Department of Medicine, Division of Endocrinology, Diabetes & Metabolism, University of Wisconsin-Madison, Madison, WI
- William S. Middleton Memorial Veterans Hospital, Madison, WI
- Department of Biomolecular Chemistry, University of Wisconsin-Madison, Madison, WI
| | - Weibo Cai
- Department of Medical Physics, University of Wisconsin-Madison, Madison, WI
- Carbone Cancer Center, University of Wisconsin-Madison, Madison, WI
- Department of Radiology, University of Wisconsin-Madison, Madison, WI
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12
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Eve DJ, Sanberg PR. Article Commentary: Regenerative Medicine: An Analysis of Cell Transplantation's Impact. Cell Transplant 2017; 16:751-764. [DOI: 10.3727/000000007783465136] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/21/2022] Open
Affiliation(s)
- David J. Eve
- Center of Excellence for Aging and Brain Repair, Department of Neurosurgery, University of South Florida College of Medicine, Tampa, FL 33612, USA
| | - Paul R. Sanberg
- Center of Excellence for Aging and Brain Repair, Department of Neurosurgery, University of South Florida College of Medicine, Tampa, FL 33612, USA
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13
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Atanasijevic T, Bouraoud N, McGavern DB, Koretsky AP. Transcranial manganese delivery for neuronal tract tracing using MEMRI. Neuroimage 2017; 156:146-154. [PMID: 28506873 DOI: 10.1016/j.neuroimage.2017.05.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/26/2016] [Revised: 04/27/2017] [Accepted: 05/12/2017] [Indexed: 11/17/2022] Open
Abstract
There has been a growing interest in the use of manganese-enhanced MRI (MEMRI) for neuronal tract tracing in mammals, especially in rodents. For this MEMRI application, manganese solutions are usually directly injected into specific brain regions. Recently it was reported that manganese ions can diffuse through intact rat skull. Here the local manganese concentrations in the brain tissue after transcranial manganese application were quantified and the effectiveness of tracing from the area under the skull where delivery occurred was determined. It was established that transcranially applied manganese yields brain tissue enhancement dependent on the location of application on the skull and that manganese that enters the brain transcranially can trace to deeper brain areas.
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Affiliation(s)
- Tatjana Atanasijevic
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Nadia Bouraoud
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Dorian B McGavern
- Laboratory of Viral Immunology and Intravital Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
| | - Alan P Koretsky
- Laboratory of Functional and Molecular Imaging, National Institute of Neurological Disorders and Stroke, National Institutes of Health, Bethesda, MD 20892, USA.
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14
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Laurent D, Vinet L, Lamprianou S, Daval M, Filhoulaud G, Ktorza A, Wang H, Sewing S, Juretschke HP, Glombik H, Meda P, Boisgard R, Nguyen DL, Stasiuk GJ, Long NJ, Montet X, Hecht P, Kramer W, Rutter GA, Hecksher-Sørensen J. Pancreatic β-cell imaging in humans: fiction or option? Diabetes Obes Metab 2016; 18:6-15. [PMID: 26228188 DOI: 10.1111/dom.12544] [Citation(s) in RCA: 30] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/15/2015] [Revised: 07/02/2015] [Accepted: 07/28/2015] [Indexed: 01/02/2023]
Abstract
Diabetes mellitus is a growing worldwide epidemic disease, currently affecting 1 in 12 adults. Treatment of disease complications typically consumes ∼10% of healthcare budgets in developed societies. Whilst immune-mediated destruction of insulin-secreting pancreatic β cells is responsible for Type 1 diabetes, both the loss and dysfunction of these cells underly the more prevalent Type 2 diabetes. The establishment of robust drug development programmes aimed at β-cell restoration is still hampered by the absence of means to measure β-cell mass prospectively in vivo, an approach which would provide new opportunities for understanding disease mechanisms and ultimately assigning personalized treatments. In the present review, we describe the progress towards this goal achieved by the Innovative Medicines Initiative in Diabetes, a collaborative public-private consortium supported by the European Commission and by dedicated resources of pharmaceutical companies. We compare several of the available imaging methods and molecular targets and provide suggestions as to the likeliest to lead to tractable approaches. Furthermore, we discuss the simultaneous development of animal models that can be used to measure subtle changes in β-cell mass, a prerequisite for validating the clinical potential of the different imaging tracers.
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Affiliation(s)
- D Laurent
- Biomarker Department, Clinical Imaging, Novartis Institutes for Biomedical Research, Basel, Switzerland
| | - L Vinet
- Department of Genetic Medicine and Development, University of Geneva, Geneva, Switzerland
| | - S Lamprianou
- Department of Genetic Medicine and Development, University of Geneva, Geneva, Switzerland
| | - M Daval
- Metabolic Diseases Department, Servier Research Institute, Suresnes, France
| | - G Filhoulaud
- Metabolic Diseases Department, Servier Research Institute, Suresnes, France
| | - A Ktorza
- Metabolic Diseases Department, Servier Research Institute, Suresnes, France
| | - H Wang
- Roche Pharma Research and Early Development, Innovation Center Basel, Basel, Switzerland
| | - S Sewing
- Roche Pharma Research and Early Development, Innovation Center Basel, Basel, Switzerland
| | - H-P Juretschke
- Sanofi-Aventis Deutschland GmbH, Frankfurt am Main, Germany
| | - H Glombik
- Sanofi-Aventis Deutschland GmbH, Frankfurt am Main, Germany
| | - P Meda
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - R Boisgard
- Commissariat à l'Energie Atomique, Equipe d'Imagerie Moléculaire Expérimentale, Orsay, France
| | - D L Nguyen
- Commissariat à l'Energie Atomique, Equipe d'Imagerie Moléculaire Expérimentale, Orsay, France
| | - G J Stasiuk
- Department of Chemistry, Imperial College London, London, UK
| | - N J Long
- Department of Chemistry, Imperial College London, London, UK
| | - X Montet
- Department of Radiology, Geneva University Hospital, Geneva, Switzerland
| | - P Hecht
- IMIDIA Project Office, Graz, Austria
| | - W Kramer
- Scientific Consultant for Sanofi Deutschland GmbH, Frankfurt am Main, Germany
| | - G A Rutter
- Section of Cell Biology and Functional Genomics, Department of Medicine, Imperial Centre for Translational and Experimental Medicine, Imperial College London, Hammersmith Hospital, London, UK
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15
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Meyer A, Stolz K, Dreher W, Bergemann J, Holebasavanahalli Thimmashetty V, Lueschen N, Azizi Z, Khobragade V, Maedler K, Kuestermann E. Manganese-mediated MRI signals correlate with functional β-cell mass during diabetes progression. Diabetes 2015; 64:2138-47. [PMID: 25804940 DOI: 10.2337/db14-0864] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/30/2014] [Accepted: 01/13/2015] [Indexed: 11/13/2022]
Abstract
Diabetes diagnostic therapy and research would strongly benefit from noninvasive accurate imaging of the functional β-cells in the pancreas. Here, we developed an analysis of functional β-cell mass (BCM) by measuring manganese (Mn(2+)) uptake kinetics into glucose-stimulated β-cells by T1-weighted in vivo Mn(2+)-mediated MRI (MnMRI) in C57Bl/6J mice. Weekly MRI analysis during the diabetes progression in mice fed a high-fat/high-sucrose diet (HFD) showed increased Mn(2+)-signals in the pancreas of the HFD-fed mice during the compensation phase, when glucose tolerance and glucose-stimulated insulin secretion (GSIS) were improved and BCM was increased compared with normal diet-fed mice. The increased signal was only transient; from the 4th week on, MRI signals decreased significantly in the HFD group, and the reduced MRI signal in HFD mice persisted over the whole 12-week experimental period, which again correlated with both impaired glucose tolerance and GSIS, although BCM remained unchanged. Rapid and significantly decreased MRI signals were confirmed in diabetic mice after streptozotocin (STZ) injection. No long-term effects of Mn(2+) on glucose tolerance were observed. Our optimized MnMRI protocol fulfills the requirements of noninvasive MRI analysis and detects already small changes in the functional BCM.
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Affiliation(s)
- Anke Meyer
- Centre for Biomolecular Interactions Bremen, University of Bremen, Bremen, Germany
| | - Katharina Stolz
- Centre for Biomolecular Interactions Bremen, University of Bremen, Bremen, Germany
| | | | - Jennifer Bergemann
- Centre for Biomolecular Interactions Bremen, University of Bremen, Bremen, Germany
| | | | - Navina Lueschen
- Centre for Biomolecular Interactions Bremen, University of Bremen, Bremen, Germany
| | - Zahra Azizi
- Centre for Biomolecular Interactions Bremen, University of Bremen, Bremen, Germany
| | - Vrushali Khobragade
- Centre for Biomolecular Interactions Bremen, University of Bremen, Bremen, Germany
| | - Kathrin Maedler
- Centre for Biomolecular Interactions Bremen, University of Bremen, Bremen, Germany
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16
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Gao X, Sandberg M, Quach M, Bodin B, Johansson L, Jansson L. Effects of Mn-DPDP and manganese chloride on hemodynamics and glucose tolerance in anesthetized rats. Acta Radiol 2014; 55:328-34. [PMID: 23963152 DOI: 10.1177/0284185113499327] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
BACKGROUND Previous studies have demonstrated that magnetic resonance imaging may be a method of choice to visualize transplanted pancreatic islets. However, contrast agents may interfere with microcirculation and affect graft function. PURPOSE To evaluate the effects manganese-containing contrast media on regional blood flow and glucose tolerance. MATERIAL AND METHODS Anesthetized rats were injected intravenously with MnCl2 (10 µM/kg body weight) or Mn-DPDP (Teslascan™; 5 µM/kg body weight). Blood flow measurements were made with a microsphere technique 10 min later. In separate animals vascular arteriolar reactivity in isolated, perfused islets was examined. Furthermore, an intraperitoneal glucose tolerance test was performed in separate rats. RESULTS Glucose tolerance was unaffected by both agents. No changes in regional blood flow were seen after administration of Mn-DPDP, except for an increase in arterial liver blood flow. MnCl2 increased all blood flow values except that of the kidney. MnCl2, but not Mn-DPDP, caused a vasoconstriction in isolated rat islet arterioles but only at very high doses. CONCLUSION Mn-DPDP administration does not affect glucose tolerance or regional blood flow, besides an increase in arterial hepatic blood flow, and may therefore be suitable for visualization of islets.
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Affiliation(s)
- Xiang Gao
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Monica Sandberg
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - My Quach
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Birgitta Bodin
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
| | - Lars Johansson
- Department of Radiology, Uppsala University Hospital, Uppsala, Sweden
| | - Leif Jansson
- Department of Medical Cell Biology, Uppsala University, Uppsala, Sweden
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17
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18
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Antkowiak PF, Stevens BK, Nunemaker CS, McDuffie M, Epstein FH. Manganese-enhanced magnetic resonance imaging detects declining pancreatic β-cell mass in a cyclophosphamide-accelerated mouse model of type 1 diabetes. Diabetes 2013; 62:44-8. [PMID: 22933107 PMCID: PMC3526033 DOI: 10.2337/db12-0153] [Citation(s) in RCA: 25] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Currently, there is no ideal noninvasive method to quantify the progressive loss of pancreatic β-cell mass (BCM) that occurs in type 1 diabetes. Magnetic resonance imaging has detected gross differences in BCM between healthy and diabetic mice using the contrast agent manganese, which labels functional β-cells and increases the water proton relaxation rate (R1), but its ability to measure gradations in BCM during disease progression is unknown. Our objective was to test the hypothesis that measurements of the manganese-enhanced pancreatic R1 could detect decreasing BCM in a mouse model of type 1 diabetes. We used cyclophosphamide-accelerated BDC2.5 T-cell receptor transgenic nonobese diabetic mice, which experience development of type 1 diabetes during a 7-day time period after cyclophosphamide injection, whereas transgene-negative mice do not. We measured the manganese-enhanced pancreatic R1 before cyclophosphamide injection (day 0) and on days 3, 4, 5, and 7 afterward. Pancreatic R1 remained constant in transgene-negative mice and decreased stepwise day-to-day in transgene-positive mice, mirroring their loss of BCM, confirmed by pancreatic insulin measurements and histology. Changes in R1 in transgene-positive mice occurred before elevations in blood glucose, a clinical indicator of diabetes, suggesting potential for early noninvasive detection of changes in functional BCM.
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Affiliation(s)
- Patrick F. Antkowiak
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia
| | - Brian K. Stevens
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia
| | - Craig S. Nunemaker
- Department of Medicine, University of Virginia, Charlottesville, Virginia
| | - Marcia McDuffie
- Department of Microbiology, Immunology, and Cancer Biology, University of Virginia, Charlottesville, Virginia
- Department of Medicine, University of Virginia, Charlottesville, Virginia
| | - Frederick H. Epstein
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia
- Department of Radiology, University of Virginia, Charlottesville, Virginia
- Corresponding author: Frederick H. Epstein,
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19
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Di Gialleonardo V, de Vries EFJ, Di Girolamo M, Quintero AM, Dierckx RAJO, Signore A. Imaging of β-cell mass and insulitis in insulin-dependent (Type 1) diabetes mellitus. Endocr Rev 2012; 33:892-919. [PMID: 22889646 DOI: 10.1210/er.2011-1041] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
Insulin-dependent (type 1) diabetes mellitus is a metabolic disease with a complex multifactorial etiology and a poorly understood pathogenesis. Genetic and environmental factors cause an autoimmune reaction against pancreatic β-cells, called insulitis, confirmed in pancreatic samples obtained at autopsy. The possibility to noninvasively quantify β-cell mass in vivo would provide important biological insights and facilitate aspects of diagnosis and therapy, including follow-up of islet cell transplantation. Moreover, the availability of a noninvasive tool to quantify the extent and severity of pancreatic insulitis could be useful for understanding the natural history of human insulin-dependent (type 1) diabetes mellitus, to early diagnose children at risk to develop overt diabetes, and to select patients to be treated with immunotherapies aimed at blocking the insulitis and monitoring the efficacy of these therapies. In this review, we outline the imaging techniques currently available for in vivo, noninvasive detection of β-cell mass and insulitis. These imaging techniques include magnetic resonance imaging, ultrasound, computed tomography, bioluminescence and fluorescence imaging, and the nuclear medicine techniques positron emission tomography and single-photon emission computed tomography. Several approaches and radiopharmaceuticals for imaging β-cells and lymphocytic insulitis are reviewed in detail.
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Affiliation(s)
- Valentina Di Gialleonardo
- Department of Nuclear Medicine and Molecular Imaging, University Medical Center Groningen, University of Groningen, 9700 AB, Groningen, The Netherlands
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20
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Dhyani AH, Fan X, Leoni L, Haque M, Roman BB. Empirical mathematical model for dynamic manganese-enhanced MRI of the murine pancreas for assessment of β-cell function. Magn Reson Imaging 2012; 31:508-14. [PMID: 23102946 DOI: 10.1016/j.mri.2012.09.003] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/11/2012] [Revised: 09/11/2012] [Accepted: 09/12/2012] [Indexed: 12/25/2022]
Abstract
Autoimmune ablation of pancreatic β-cells and alteration of its microvasculature may be a predictor of Type I diabetes development. A dynamic manganese-enhanced MRI (MEMRI) approach and an empirical mathematical model were developed to monitor whole pancreatic β-cell function and vasculature modifications in mice. Normal and streptozotocin-induced diabetic FVB/N mice were imaged on a 9.4T MRI system using a 3D magnetization prepared rapid acquisition gradient echo pulse sequence to characterize low dose manganese kinetics in the pancreas head, body and tail. Average signal enhancement in the pancreas (head, body, and tail) as a function of time was fit by a novel empirical mathematical model characterizing contrast uptake/washout rates and yielding parameters describing peak signal, initial slope, and initial area under the curve. Signal enhancement from glucose-induced manganese uptake was fit by a linear function. The results demonstrated that the diabetic pancreatic tail had a significantly lower contrast uptake rate, smaller initial slope/initial area under the curve, and a smaller rate of Mn uptake following glucose activation (p<0.05) compared to the normal pancreatic tail. These observations parallel known patterns of β-cell loss and alteration in supportive vasculature associated with diabetes. Dynamic MEMRI is a promising technique for assessing β-cell functionality and vascular perfusion with potential applications for monitoring diabetes progression and/or therapy.
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Affiliation(s)
- Anita H Dhyani
- Department of Radiology, MC2026, University of Chicago, Chicago, IL 60637, USA
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21
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Malaisse WJ, Maedler K. Imaging of the β-cells of the islets of Langerhans. Diabetes Res Clin Pract 2012; 98:11-8. [PMID: 22854107 DOI: 10.1016/j.diabres.2012.07.001] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/10/2012] [Accepted: 07/10/2012] [Indexed: 01/09/2023]
Abstract
The major aim of this paper is to review the present status of the techniques for the non-invasive imaging and quantification of insulin-producing pancreatic islet β-cells. Emphasis is placed on both the expansion of prior work already considered in a prior review and novel achievements. Thus, the use of d-mannoheptulose analogs, hypoglycemic sulfonylureas and glinides, neural imaging agents, neuro-hormonal receptor ligands and nanoparticles is first dealt with. Thereafter, consideration is given on optical imaging technologies, the identification of new β-cells specific binding and target proteins, the functional imaging of islets transplanted into the eye anterior chamber and in vivo manganese-enhanced magnetic resonance imaging.
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Affiliation(s)
- Willy J Malaisse
- Laboratory of Experimental Hormonology, Université Libre de Bruxelles, Brussels, Belgium.
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22
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Botsikas D, Terraz S, Vinet L, Lamprianou S, Becker C, Bosco D, Meda P, Montet X. Pancreatic magnetic resonance imaging after manganese injection distinguishes type 2 diabetic and normoglycemic patients. Islets 2012; 4:243-8. [PMID: 22722479 PMCID: PMC3442822 DOI: 10.4161/isl.20857] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
A non-invasive method to image the mass and/or function of human pancreatic islets is needed to monitor the progression of diabetes, and the effect of therapeutic interventions. As yet, no method is available for this purpose, which could be applied to in situ human islets. Animal and in vitro studies have documented that manganese infusion could improve the magnetic resonance imaging (MRI) of the endocrine pancreas. Here, we have tested whether a similar approach could discriminate diabetic and non-diabetic patients. In vitro, human isolated islets readily incorporated manganese. In vivo, 243 manganese-enhanced magnetic resonance imaging (MEMRI) examinations were reviewed, including 41 examinations which were run on 24 patients with type 2 diabetes and 202 examinations which were run on 119 normoglycemic patients. The results show that MEMRI discriminates type 2 diabetics from non-diabetic patients, based on the signal enhancement of pancreas.
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Affiliation(s)
- Diomidis Botsikas
- Department of Radiology; Geneva University Hospital; Geneva, Switzerland
| | - Sylvain Terraz
- Department of Radiology; Geneva University Hospital; Geneva, Switzerland
| | - Laurent Vinet
- Department of Cell Physiology and Metabolism; Geneva University; Geneva, Switzerland
| | - Smaragda Lamprianou
- Department of Cell Physiology and Metabolism; Geneva University; Geneva, Switzerland
| | - Christoph Becker
- Department of Radiology; Geneva University Hospital; Geneva, Switzerland
| | - Domenico Bosco
- Department of Surgery; Geneva University Hospital; Geneva, Switzerland
| | - Paolo Meda
- Department of Cell Physiology and Metabolism; Geneva University; Geneva, Switzerland
| | - Xavier Montet
- Department of Radiology; Geneva University Hospital; Geneva, Switzerland
- Correspondence to: Xavier Montet,
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23
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Andralojc K, Srinivas M, Brom M, Joosten L, de Vries IJM, Eizirik DL, Boerman OC, Meda P, Gotthardt M. Obstacles on the way to the clinical visualisation of beta cells: looking for the Aeneas of molecular imaging to navigate between Scylla and Charybdis. Diabetologia 2012; 55:1247-57. [PMID: 22358499 PMCID: PMC3328679 DOI: 10.1007/s00125-012-2491-7] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 09/21/2011] [Accepted: 01/09/2012] [Indexed: 12/25/2022]
Abstract
For more than a decade, researchers have been trying to develop non-invasive imaging techniques for the in vivo measurement of viable pancreatic beta cells. However, in spite of intense research efforts, only one tracer for positron emission tomography (PET) imaging is currently under clinical evaluation. To many diabetologists it may remain unclear why the imaging world struggles to develop an effective method for non-invasive beta cell imaging (BCI), which could be useful for both research and clinical purposes. Here, we provide a concise overview of the obstacles and challenges encountered on the way to such BCI, in both native and transplanted islets. We discuss the major difficulties posed by the anatomical and cell biological features of pancreatic islets, as well as the chemical and physical limits of the main imaging modalities, with special focus on PET, SPECT and MRI. We conclude by indicating new avenues for future research in the field, based on several remarkable recent results.
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Affiliation(s)
- K. Andralojc
- Department of Nuclear Medicine, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, the Netherlands
| | - M. Srinivas
- Department of Tumour Immunology, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands
| | - M. Brom
- Department of Nuclear Medicine, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, the Netherlands
| | - L. Joosten
- Department of Nuclear Medicine, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, the Netherlands
| | - I. J. M. de Vries
- Department of Tumour Immunology, Radboud University Nijmegen Medical Centre, Nijmegen, the Netherlands
| | - D. L. Eizirik
- Laboratory of Experimental Medicine, Université Libre de Bruxelles, Brussels, Belgium
| | - O. C. Boerman
- Department of Nuclear Medicine, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, the Netherlands
| | - P. Meda
- Deparment of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland
| | - M. Gotthardt
- Department of Nuclear Medicine, Radboud University Nijmegen Medical Centre, PO Box 9101, 6500 HB Nijmegen, the Netherlands
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24
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Leoni L, Dhyani A, La Riviere P, Vogt S, Lai B, Roman BB. β-Cell subcellular localization of glucose-stimulated Mn uptake by X-ray fluorescence microscopy: implications for pancreatic MRI. CONTRAST MEDIA & MOLECULAR IMAGING 2012; 6:474-81. [PMID: 22144025 DOI: 10.1002/cmmi.447] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Manganese (Mn) is a calcium (Ca) analog that has long been used as a magnetic resonance imaging (MRI) contrast agent for investigating cardiac tissue functionality, for brain mapping and for neuronal tract tracing studies. Recently, we have extended its use to investigate pancreatic β-cells and showed that, in the presence of MnCl(2), glucose-activated pancreatic islets yield significant signal enhancement in T(1)-weigheted MR images. In this study, we exploited for the first time the unique capabilities of X-ray fluorescence microscopy (XFM) to both visualize and quantify the metal in pancreatic β-cells at cellular and subcellular levels. MIN-6 insulinoma cells grown in standard tissue culture conditions had only a trace amount of Mn, 1.14 ± 0.03 × 10(-11)µg/µm(2), homogenously distributed across the cell. Exposure to 2 mM glucose and 50 µM MnCl(2) for 20 min resulted in nonglucose-dependent Mn uptake and the overall cell concentration increased to 8.99 ± 2.69 × 10(-11) µg/µm(2). When cells were activated by incubation in 16 mM glucose in the presence of 50 µM MnCl(2), a significant increase in cytoplasmic Mn was measured, reaching 2.57 ± 1.34 × 10(-10) µg/µm(2). A further rise in intracellular concentration was measured following KCl-induced depolarization, with concentrations totaling 1.25 ± 0.33 × 10(-9) and 4.02 ± 0.71 × 10(-10) µg/µm(2) in the cytoplasm and nuclei, respectively. In both activated conditions Mn was prevalent in the cytoplasm and localized primarily in a perinuclear region, possibly corresponding to the Golgi apparatus and involving the secretory pathway. These data are consistent with our previous MRI findings, confirming that Mn can be used as a functional imaging reporter of pancreatic β-cell activation and also provide a basis for understanding how subcellular localization of Mn will impact MRI contrast.
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Affiliation(s)
- Lara Leoni
- Department of Radiology, Committee on Medical Physics, University of Chicago, Chicago, IL 60637, USA
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25
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Baxan N, Kahlert U, Maciaczyk J, Nikkhah G, Hennig J, von Elverfeldt D. Microcoil-based MR phase imaging and manganese enhanced microscopy of glial tumor neurospheres with direct optical correlation. Magn Reson Med 2011; 68:86-97. [PMID: 22127877 DOI: 10.1002/mrm.23208] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2010] [Revised: 07/06/2011] [Accepted: 08/16/2011] [Indexed: 12/22/2022]
Abstract
Susceptibility differences among tissues were recently used for highlighting complementary contrast in MRI different from the conventional T(1), T(2), or spin density contrasts. This method, based on the signal phase, previously showed improved image contrast of human or rodent neuroarchitecture in vivo, although direct MR phase imaging of cellular architecture was not available until recently. In this study, we present for the first time the ability of microcoil-based phase MRI to resolve the structure of human glioma neurospheres at significantly improved resolutions (10 × 10 μm(2)) with direct optical image correlation. The manganese chloride property to function as a T(1) contrast agent enabled a closer examination of cell physiology with MRI. Specifically the temporal changes of manganese chloride uptake, retention and release time within and from individual clusters were assessed. The optimal manganese chloride concentration for improved MR signal enhancement was determined while keeping the cellular viability unaffected. The presented results demonstrate the possibilities to reveal structural and functional observation of living glioblastoma human-derived cells. This was achieved through the combination of highly sensitive microcoils, high magnetic field, and methods designed to maximize contrast to noise ratio. The presented approach may provide a powerful multimodal tool that merges structural and functional information of submilimeter biological samples.
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Affiliation(s)
- Nicoleta Baxan
- Department of Radiology, Medical Physics, University Medical Center, Freiburg, Germany.
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26
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Lamprianou S, Immonen R, Nabuurs C, Gjinovci A, Vinet L, Montet XCR, Gruetter R, Meda P. High-resolution magnetic resonance imaging quantitatively detects individual pancreatic islets. Diabetes 2011; 60:2853-60. [PMID: 21926272 PMCID: PMC3198086 DOI: 10.2337/db11-0726] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
OBJECTIVE We studied whether manganese-enhanced high-field magnetic resonance (MR) imaging (MEHFMRI) could quantitatively detect individual islets in situ and in vivo and evaluate changes in a model of experimental diabetes. RESEARCH DESIGN AND METHODS Whole pancreata from untreated (n = 3), MnCl(2) and glucose-injected mice (n = 6), and mice injected with either streptozotocin (STZ; n = 4) or citrate buffer (n = 4) were imaged ex vivo for unambiguous evaluation of islets. Exteriorized pancreata of MnCl(2) and glucose-injected mice (n = 6) were imaged in vivo to directly visualize the gland and minimize movements. In all cases, MR images were acquired in a 14.1 Tesla scanner and correlated with the corresponding (immuno)histological sections. RESULTS In ex vivo experiments, MEHFMRI distinguished different pancreatic tissues and evaluated the relative abundance of islets in the pancreata of normoglycemic mice. MEHFMRI also detected a significant decrease in the numerical and volume density of islets in STZ-injected mice. However, in the latter measurements the loss of β-cells was undervalued under the conditions tested. The experiments on the externalized pancreata confirmed that MEHFMRI could visualize native individual islets in living, anesthetized mice. CONCLUSIONS Data show that MEHFMRI quantitatively visualizes individual islets in the intact mouse pancreas, both ex vivo and in vivo.
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Affiliation(s)
- Smaragda Lamprianou
- Department of Cell Physiology and Metabolism, University of Geneva, Geneva, Switzerland.
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27
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Molecular imaging: a promising tool to monitor islet transplantation. J Transplant 2011; 2011:202915. [PMID: 22013504 PMCID: PMC3195545 DOI: 10.1155/2011/202915] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2011] [Accepted: 07/29/2011] [Indexed: 12/18/2022] Open
Abstract
Replacement of insulin production by pancreatic islet transplantation has great potential as a therapy for type 1 diabetes mellitus. At present, the lack of an effective approach to islet grafts assessment limits the success of this treatment. The development of molecular imaging techniques has the potential to fulfill the goal of real-time noninvasive monitoring of the functional status and viability of the islet grafts. We review the application of a variety of imaging modalities for detecting endogenous and transplanted beta-cell mass. The review also explores the various molecular imaging strategies for assessing islet delivery, the metabolic effects on the islet grafts as well as detection of immunorejection. Here, we highlight the use of combined imaging and therapeutic interventions in islet transplantation and the in vivo monitoring of stem cells differentiation into insulin-producing cells.
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28
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Jahansouz C, Jahansouz C, Kumer SC, Brayman KL. Evolution of β-Cell Replacement Therapy in Diabetes Mellitus: Islet Cell Transplantation. J Transplant 2011; 2011:247959. [PMID: 22013505 PMCID: PMC3195999 DOI: 10.1155/2011/247959] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2011] [Accepted: 08/08/2011] [Indexed: 12/12/2022] Open
Abstract
Diabetes mellitus remains one of the leading causes of morbidity and mortality worldwide. According to the Centers for Disease Control and Prevention, approximately 23.6 million people in the United States are affected. Of these individuals, 5 to 10% have been diagnosed with Type 1 diabetes mellitus (T1DM), an autoimmune disease. Although it often appears in childhood, T1DM may manifest at any age, leading to significant morbidity and decreased quality of life. Since the 1960s, the surgical treatment for diabetes mellitus has evolved to become a viable alternative to insulin administration, beginning with pancreatic transplantation. While islet cell transplantation has emerged as another potential alternative, its role in the treatment of T1DM remains to be solidified as research continues to establish it as a truly viable alternative for achieving insulin independence. In this paper, the historical evolution, procurement, current status, benefits, risks, and ongoing research of islet cell transplantation are explored.
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Affiliation(s)
- Cyrus Jahansouz
- School of Medicine, University of Virginia, Charlottesville, VA 22102, USA
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Antkowiak PF, Vandsburger MH, Epstein FH. Quantitative pancreatic β cell MRI using manganese-enhanced Look-Locker imaging and two-site water exchange analysis. Magn Reson Med 2011; 67:1730-9. [PMID: 22189705 DOI: 10.1002/mrm.23139] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2010] [Revised: 06/16/2011] [Accepted: 07/14/2011] [Indexed: 12/20/2022]
Abstract
Pancreatic β-cell imaging would be useful in monitoring the progression of and therapies for diabetes. The purpose of this study was to develop and evaluate quantitative β-cell MRI using manganese (Mn(2+)) labeling of β cells, T1 mapping, and a two-site water exchange model. Normal, pharmacologically-treated, and severely diabetic mice underwent injection of MnCl(2). Pancreatic water proton T1 relaxation was measured using Look-Locker MRI, and two-site water exchange analysis was used to estimate model parameters including the intracellular water proton relaxation rate constant (R1(ic)) and the intracellular fraction as indicators of β-cell function and mass, respectively. Logarithmic plots of T1 relaxation revealed two distinct proton pools relaxing with different T1s, and the two-site water exchange model fit the measured T1 relaxation data better than a monoexponential model. The intracellular R1(ic) time course revealed the kinetics of β-cell Mn(2+) labeling. Pharmacological treatments with nifedipine, tolbutamide, and diazoxide altered R1(ic), indicating that beta cell function was a determinant of Mn(2+) uptake. Intracellular fraction was significantly higher in mice with normal β cell mass than in diabetic mice (14.9% vs. 14.4%, P < 0.05). Two-site water exchange analysis of T1 relaxation of the Mn(2+)-enhanced pancreas is a promising method for quantifying β cell volume fraction and function.
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Affiliation(s)
- Patrick F Antkowiak
- Department of Biomedical Engineering, University of Virginia, Charlottesville, Virginia 22908, USA
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Chesnick IE, Centeno JA, Todorov TI, Koenig AE, Potter K. Spatial mapping of mineralization with manganese-enhanced magnetic resonance imaging. Bone 2011; 48:1194-201. [PMID: 21352960 PMCID: PMC3113632 DOI: 10.1016/j.bone.2011.02.014] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 10/22/2010] [Revised: 02/03/2011] [Accepted: 02/16/2011] [Indexed: 10/18/2022]
Abstract
Paramagnetic manganese can be employed as a calcium surrogate to sensitize the magnetic resonance imaging (MRI) technique to the processing of calcium during the bone formation process. At low doses, after just 48h of exposure, osteoblasts take up sufficient quantities of manganese to cause marked reductions in the water proton T1 values compared with untreated cells. After just 24h of exposure, 25μM MnCl(2) had no significant effect on cell viability. However, for mineralization studies 100μM MnCl(2) was used to avoid issues of manganese depletion in calvarial organ cultures and a post-treatment delay of 48h was implemented to ensure that manganese ions taken up by osteoblasts is deposited as mineral. All specimens were identified by their days in vitro (DIV). Using inductively coupled plasma optical emission spectroscopy (ICP-OES), we confirmed that Mn-treated calvariae continued to deposit mineral in culture and that the mineral composition was similar to that of age-matched controls. Notably there was a significant decrease in the manganese content of DIV18 compared with DIV11 specimens, possibly relating to less manganese sequestration as a result of mineral maturation. More importantly, quantitative T1 maps of Mn-treated calvariae showed localized reductions in T1 values over the calvarial surface, indicative of local variations in the surface manganese content. This result was verified with laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS). We also found that ΔR1 values, calculated by subtracting the relaxation rate of Mn-treated specimens from the relaxation rate of age-matched controls, were proportional to the surface manganese content and thus mineralizing activity. From this analysis, we established that mineralization of DIV4 and DIV11 specimens occurred in all tissue zones, but was reduced for DIV18 specimens because of mineral maturation with less manganese sequestration. In DIV25 specimens, active mineralization was observed for the expanding superficial surface and ΔR1 values were increased due to the mineralization of small, previously unmineralized areas. Our findings support the use of manganese-enhanced MRI (MEMRI) to study well-orchestrated mineralizing events that occur during embryonic development. In conclusion, MEMRI is more sensitive to the study of mineralization than traditional imaging approaches.
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Affiliation(s)
- Ingrid E. Chesnick
- Magnetic Resonance Microscopy Facility, Department of Biophysics, Armed Forces Institute of Pathology Annex, Rockville, MD, USA
| | - Jose A. Centeno
- Department of Environmental and Infectious Disease Sciences, Armed Forces Institute of Pathology, Washington, DC, USA
| | - Todor I. Todorov
- Crustal Imaging and Characterization Team, United States Geological Survey, Denver, CO, USA
| | - Alan E. Koenig
- Crustal Imaging and Characterization Team, United States Geological Survey, Denver, CO, USA
| | - Kimberlee Potter
- Magnetic Resonance Microscopy Facility, Department of Biophysics, Armed Forces Institute of Pathology Annex, Rockville, MD, USA
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Leoni L, Serai SD, Haque ME, Magin RL, Roman BB. Functional MRI characterization of isolated human islet activation. NMR IN BIOMEDICINE 2010; 23:1158-1165. [PMID: 21162143 DOI: 10.1002/nbm.1542] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/13/2009] [Revised: 02/05/2010] [Accepted: 03/05/2010] [Indexed: 05/30/2023]
Abstract
The noninvasive assessment of pancreatic islets would be an invaluable tool in advancing the treatment of type I diabetes and in understanding its pathophysiology. As shown previously in rodents, manganese-enhanced MRI (MEMRI) can be successfully used to quantify β-cell function. In this study, we successfully applied this technique to isolated human pancreatic islets in both a static and, more significantly, MRI-compatible perfusion set-up. Unlike rodent islets, which produced a significant increase in the signal-to-noise ratio (SNR) when treated with 25 µM MnCl(2) or less, human islets demonstrated significant manganese uptake when exposed to an extracellular concentration of 50 µM MnCl(2). Nonspecific passive manganese uptake was present and quantified in a 15% SNR increase over the control group. However, glucose-induced manganese uptake caused an SNR increase equal to 45% over nonactivated islets. This corresponds to a statistically significant decrease in the T(1) relaxation time from 1501 ms for untreated islets to 1362 ms following passive uptake, and to 861 ms following glucose stimulation. As expected, no manganese cytotoxicity was measured, as shown by normal insulin secretion profiles. These data confirm the viability of MEMRI to assess isolated human islet functionality in vitro, and this technique shows promise for the monitoring of their performance in vivo following transplantation.
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Affiliation(s)
- Lara Leoni
- University of Chicago, Department of Radiology, Chicago, IL, USA
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Sever D, Eldor R, Sadoun G, Amior L, Dubois D, Boitard C, Aflalo C, Melloul D. Evaluation of impaired beta-cell function in nonobese-diabetic (NOD) mouse model using bioluminescence imaging. FASEB J 2010; 25:676-84. [PMID: 21118902 DOI: 10.1096/fj.10-158121] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Abstract
Insulin-producing pancreatic β cells are functionally impaired or destroyed in diabetes mellitus. The onset of type 1 diabetes (T1D) represents the culmination of a prolonged prediabetic phase of immune-mediated β-cell destruction. To assess the in vivo metabolic status of these cells, we used the ATP-sensitive firefly luciferase bioluminescence imaging approach, as a noninvasive probe to monitor pathological alterations in β-cell function in the nonobese-diabetic (NOD) mouse model of T1D. Hence, we generated the ToIβ-NOD transgenic mice in which doxycycline-inducible luciferase gene is selectively expressed in β cells. A sharp reduction in bioluminescence emitted in vivo from β cells at the early stages, preceded by several weeks of a limited reduction in β-cell mass. Since this decline could be due to the ongoing inflammatory process occurring in vivo, we exposed control islets to inflammatory cytokines and observed a dramatic decrease in luciferase luminescence, which appears to be due in part to a decrease in protein levels and a drop in intracellular ATP levels. This is the first evidence that selective expression of the luciferase gene represents a sensitive method for noninvasive in vivo monitoring of early β-cell dysfunction, subtle metabolic changes, such as endogenous ATP levels, indicative of a pathological condition in a tissue at the cellular level.
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Affiliation(s)
- Dror Sever
- Department of Endocrinology, Hadassah University Hospital, P.O. Box 12000, 91120 Jerusalem, Israel
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Lee LW, So PW, Price AN, Parkinson JRC, Larkman DJ, Halliday J, Poucher SM, Pugh JAT, Cox AG, McLeod CW, Bell JD. Manganese enhancement in non-CNS organs. NMR IN BIOMEDICINE 2010; 23:931-938. [PMID: 20878971 DOI: 10.1002/nbm.1513] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Manganese-enhanced magnetic resonance imaging (MEMRI) is a novel imaging technique capable of monitoring calcium influx, in vivo. Manganese (Mn2+) ions, similar to calcium ions (Ca2+), are taken up by activated cells where their paramagnetic properties afford signal enhancement in T(1)-weighted MRI methodologies. In this study we have assessed Mn2+ distribution in mice using magnetization-prepared rapid gradient echo (MP-RAGE) based MRI, by measuring changes in T(1)-effective relaxation times (T(1)-eff), effective R(1)-relaxation rates (R(1)-eff) and signal intensity (SI) profiles over time. The manganese concentration in the tissue was also determined using inductively coupled plasma atomic emission spectrometry (ICP-AES). Our results show a strong positive correlation between infused dose of MnCl2 and the tissue manganese concentration. Furthermore, we demonstrate a linear relationship between R(1)-eff and tissue manganese concentration and tissue-specific Mn2+ distribution in murine tissues following dose-dependent Mn2+ administration. This data provides an optimized MnCl2 dose regimen for an MP-RAGE based sequence protocol for specific target organs and presents a potential 3D MRI technique for in vivo imaging of Ca2+ entry during Ca2+-dependent processes in a wide range of tissues.
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Affiliation(s)
- Li-Wen Lee
- Metabolic and Molecular Imaging Group, MRC Clinical Sciences Centre, Hammersmith Hospital Campus, Imperial College London, London, UK
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Han W, Chuang KH, Chang YT, Olivo M, Velan SS, Bhakoo K, Townsend D, Radda GK. Imaging metabolic syndrome. EMBO Mol Med 2010; 2:196-210. [PMID: 20533426 PMCID: PMC3377322 DOI: 10.1002/emmm.201000074] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Metabolic syndrome is a fast growing public health burden for almost all the developed countries and many developing nations. Despite intense efforts from both biomedical and clinical scientists, many fundamental questions regarding its aetiology and development remain unclear, partly due to the lack of suitable imaging technologies to visualize lipid composition and distribution, insulin secretion, β-cell mass and functions in vivo. Such technologies would not only impact on our understanding of the complexity of metabolic disorders such as obesity and diabetes, but also aid in their diagnosis, drug development and assessment of treatment efficacy. In this article we discuss and propose several strategies for visualization of physiological and pathological changes that affect pancreas and adipose tissue as a result of the development of metabolic diseases.
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Affiliation(s)
- Weiping Han
- Singapore Bioimaging Consortium, Agency for Science Technology and Research (A*STAR), Singapore, Singapore
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Nagata M, Kagawa T, Koutou D, Matsushita T, Yamazaki Y, Murase K. Measurement of manganese content in various organs in rats with or without glucose stimulation. Radiol Phys Technol 2010; 4:7-12. [PMID: 20820965 DOI: 10.1007/s12194-010-0098-6] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/28/2010] [Revised: 07/15/2010] [Accepted: 07/20/2010] [Indexed: 12/27/2022]
Abstract
Our purpose in this study was to assess the manganese (Mn) content in various organs in rats with or without glucose stimulation in vivo and in vitro by using magnetic resonance imaging (MRI) and polarized Zeeman atomic absorption spectrophotometry (PZAAS), respectively. MRI studies were performed in 12 rats using a 1.5-T MRI system. The rats were injected intravenously with saline (6 ml/kg) (saline-stimulated group, n = 6) or glucose (2.34 g/kg) (glucose-stimulated group, n = 6). Ten minutes after saline or glucose administration, MnCl₂ (0.02 mmol/kg) was injected intravenously, followed by 6 MRI studies at 8-min intervals. After the last MRI study, rats were killed, and the Mn concentrations in various organs were measured using PZAAS. There was a discrepancy between in vivo and in vitro measurements, which appeared to be due to the partial volume effect and/or the contribution of extracellular Mn. The Mn concentration in the pancreas, normalized to that in the liver in the glucose-stimulated group, increased significantly compared to that in the saline-stimulated group, suggesting that the influx of Mn into β cells in the pancreas increased in response to glucose stimulation. This study suggested that the measurement of the change in the Mn concentration due to glucose stimulation using PZAAS was effective for evaluating β-cell function in the pancreas.
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Affiliation(s)
- Mamoru Nagata
- Division of Medical Technology and Science, Department of Medical Physics and Engineering, Faculty of Health Science, Graduate School of Medicine, Osaka University, 1-7 Yamadaoka, Suita, Osaka, 565-0871, Japan
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Adewola AF, Lee D, Harvat T, Mohammed J, Eddington DT, Oberholzer J, Wang Y. Microfluidic perifusion and imaging device for multi-parametric islet function assessment. Biomed Microdevices 2010; 12:409-17. [PMID: 20300858 DOI: 10.1007/s10544-010-9398-1] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Abstract
A microfluidic islet perifusion device was developed for the assessment of dynamic insulin secretion of multiple pancreatic islets and simultaneous fluorescence imaging of calcium influx and mitochondrial potential changes. The fanned out design of the second generation device optimized the efficient mixing and uniform distribution of rapid alternating solutions in the perifusion chamber and allowed for the generation of reproducible glucose gradients. Simultaneous imaging of calcium influx and mitochondrial potential changes in response to glucose stimulation showed high signal-noise ratio and spatial-temporal resolution. These results suggest that this system can be used for detailed study of the endocrine function of pancreatic islets with simultaneous imaging of intracellular ion fluxes and mitochondrial membrane potential changes. This tool can be used for quality assessment of islets preparation before transplantation and for in vitro studies of islet function.
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Affiliation(s)
- Adeola F Adewola
- Department of Transplant/Surgery, University of Illinois, Chicago, IL, USA
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Riviere PJL, Vargas P, Fu G, Meng LJ. Accelerating X-ray fluorescence computed tomography. ANNUAL INTERNATIONAL CONFERENCE OF THE IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. IEEE ENGINEERING IN MEDICINE AND BIOLOGY SOCIETY. ANNUAL INTERNATIONAL CONFERENCE 2010; 2009:1000-3. [PMID: 19964256 DOI: 10.1109/iembs.2009.5333568] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/07/2022]
Abstract
This paper presents new approaches to accelerating X-ray fluorescence tomography (XFCT) that are grounded in both novel image acquisition strategies that improve the quality of the data acquired and in image reconstruction strategies that reduce the amount of data acquired. First, we introduce an alternative imaging scheme that uses an emission tomography (ET) system to collect the fluorescence photons representing an entire 2D slice or volumetric projection of the object at one time. Preliminary results indicate that this could achieve a ten to hundredfold improvement in imaging speed. Secondly, novel image reconstruction algorithms are introduced that allow for improved quantitative accuracy as well as for imaging of regions of interest, which will lead to further reduction in data-acquisition time.
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Affiliation(s)
- P J La Riviere
- Department of Radiology, University of Chicago, Chicago, IL, USA
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Abstract
The development of new methods for noninvasive imaging is an area of biotechnology that is of great relevance for the diagnosis and characterization of diabetes mellitus. Noninvasive imaging can be used to study the dynamics of beta-cell mass and function; beta-cell death; vascularity, innervation and autoimmune attack of pancreatic islets; and the efficacy of islet transplantation to remedy beta-cell loss in patients with diabetes mellitus. In this Review, we focus on the application of MRI for monitoring islet transplantation and on the potential causes of islet graft failure, which are still poorly understood. Questions that have been addressed by MRI studies encompass graft longevity, and the effects of immune rejection, glucose toxic effects, and the transplanted islets' purity on graft fate. We also highlight novel technologies for simultaneous imaging and delivery of experimental therapies that aim to extend the lifespan and functionality of islet grafts. On the basis of this evidence, MRI represents a valuable platform for a thorough investigation of beta-cell function in the context of islet transplantation. State-of-the-art multimodality approaches, such as PET-MRI, can extend our current capabilities and help answer the critical questions that currently inhibit the prevention and cure of diabetes mellitus.
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Affiliation(s)
- Zdravka Medarova
- Molecular Imaging Laboratory, Massachusetts General Hospital-Massachusetts Institute of Technology-Harvard Medical School, Athinoula A. Martinos Center for Biomedical Imaging, 13th Street, Charlestown, MA 02129, USA
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Bioluminescence imaging in mouse models quantifies beta cell mass in the pancreas and after islet transplantation. Mol Imaging Biol 2009; 12:42-53. [PMID: 19548035 DOI: 10.1007/s11307-009-0240-1] [Citation(s) in RCA: 53] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/16/2008] [Revised: 02/28/2009] [Accepted: 04/28/2009] [Indexed: 12/26/2022]
Abstract
PURPOSE We developed a mouse model that enables non-invasive assessment of changes in beta cell mass. PROCEDURES We generated a transgenic mouse expressing luciferase under control of the mouse insulin I promoter [mouse insulin promoter-luciferase-Vanderbilt University (MIP-Luc-VU)] and characterized this model in mice with increased or decreased beta cell mass and after islet transplantation. RESULTS Streptozotocin-induced, diabetic MIP-Luc-VU mice had a progressive decline in bioluminescence that correlated with a decrease in beta cell mass. MIP-Luc-VU animals fed a high-fat diet displayed a progressive increase in bioluminescence that reflected an increase in beta cell mass. MIP-Luc-VU islets transplanted beneath the renal capsule or into the liver emitted bioluminescence proportional to the number of islets transplanted and could be imaged for more than a year. CONCLUSIONS Bioluminescence in the MIP-Luc-VU mouse model is proportional to beta cell mass in the setting of increased and decreased beta cell mass and after transplantation.
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Abstract
Diabetes mellitus results in impaired insulin production by pancreatic beta-cells due to their death and/or dysfunction. There is a growing unmet need among diabetes researches and clinicians to assess the level of surviving beta-cells non-invasively. This review will focus on employment of state-of-the-art in vivo imaging methods to estimate and evaluate beta-cell mass in animal models of diabetes.
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Affiliation(s)
- Anna Moore
- Molecular Imaging Laboratory, MGH/MIT/HMS Athinoula A Martinos Center for Biomedical Imaging, Massachusetts General Hospital/Harvard Medical School, Charlestown, MA 02129, USA.
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Gimi B, Kwon J, Kuznetsov A, Vachha B, Magin RL, Philipson LH, Lee JB. A nanoporous, transparent microcontainer for encapsulated islet therapy. J Diabetes Sci Technol 2009; 3:297-303. [PMID: 19746206 PMCID: PMC2739746 DOI: 10.1177/193229680900300210] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
Present-day islet encapsulation techniques such as polymer microcapsules and microelectromechanical system (MEMS)-based biocapsules have shown promise in insulin replacement therapy, but they each have limitations-the permeability characteristics of existing polymeric capsules cannot be strictly controlled because of tortuosity and the large size of present-day MEMS biocapsules leads to necrotic regions within the encapsulation volume. We report on a new microcontainer to encapsulate and immunoprotect islets/beta cells that may be used for allo- or xenotransplantation in cell-based therapy. The microcontainers have membranes containing nanoslots to permit the bidirectional transport of nutrients, secretagogues, and cellular products while immunoprotecting the encapsulated cells. The 300-microm microcontainers were fabricated from an epoxy-based polymer, SU-8, with 50-microm-thick walls. Arrays of 25-nm wide slots were created in the SU-8 microcontainer lid. Isolated mouse islets were encapsulated in the microcontainer, and their physiological response to glucose was studied with fluorescence and two-photon imaging over 48 hours. The physiological response of the encapsulated islets was indistinguishable from controls. An agarose-filled microcontainer was imaged with magnetic resonance imaging to demonstrate the feasibility of future noninvasive, in vivo imaging. The SU-8 microcontainers maintained mechanical integrity upon islet loading and mechanical manipulation. Islet encapsulation, as well as the ability to visualize islet function within these transparent microcontainers, was demonstrated.
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Affiliation(s)
- Barjor Gimi
- The University of Texas Southwestern Medical Center, Dallas, Texas
- University of Texas at Dallas, Dallas, Texas
- University of Illinois at Chicago, Chicago, Illinois
| | | | | | - Behroze Vachha
- The University of Texas Southwestern Medical Center, Dallas, Texas
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Antkowiak PF, Tersey SA, Carter JD, Vandsburger MH, Nadler JL, Epstein FH, Mirmira RG. Noninvasive assessment of pancreatic beta-cell function in vivo with manganese-enhanced magnetic resonance imaging. Am J Physiol Endocrinol Metab 2009; 296:E573-8. [PMID: 19116376 PMCID: PMC2660140 DOI: 10.1152/ajpendo.90336.2008] [Citation(s) in RCA: 57] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Loss of beta-cell function in type 1 and type 2 diabetes leads to metabolic dysregulation and inability to maintain normoglycemia. Noninvasive imaging of beta-cell function in vivo would therefore provide a valuable diagnostic and research tool for quantifying progression to diabetes and response to therapeutic intervention. Because manganese (Mn(2+)) is a longitudinal relaxation time (T1)-shortening magnetic resonance imaging (MRI) contrast agent that enters cells such as pancreatic beta-cells through voltage-gated calcium channels, we hypothesized that Mn(2+)-enhanced MRI of the pancreas after glucose infusion would allow for noninvasive detection of beta-cell function in vivo. To test this hypothesis, we administered glucose and saline challenges intravenously to normal mice and mice given high or low doses of streptozotocin (STZ) to induce diabetes. Serial inversion recovery MRI was subsequently performed after Mn(2+) injection to probe Mn(2+) accumulation in the pancreas. Time-intensity curves of the pancreas (normalized to the liver) fit to a sigmoid function showed a 51% increase in signal plateau height after glucose stimulation relative to saline (P < 0.01) in normal mice. In diabetic mice given a high dose of STZ, only a 9% increase in plateau signal intensity was observed after glucose challenge (P = not significant); in mice given a low dose of STZ, a 20% increase in plateau signal intensity was seen after glucose challenge (P = 0.02). Consistent with these imaging findings, the pancreatic insulin content of high- and low-dose STZ diabetic mice was reduced about 20-fold and 10-fold, respectively, compared with normal mice. We conclude that Mn(2+)-enhanced MRI demonstrates excellent potential as a means for noninvasively monitoring beta-cell function in vivo and may have the sensitivity to detect progressive decreases in function that occur in the diabetic disease process.
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Affiliation(s)
- Patrick F Antkowiak
- Department of Biomedical Engineering, University of Virginia, Charlottesville, VA 22908, USA
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Waghorn B, Edwards T, Yang Y, Chuang KH, Yanasak N, Hu TCC. Monitoring dynamic alterations in calcium homeostasis by T (1)-weighted and T (1)-mapping cardiac manganese-enhanced MRI in a murine myocardial infarction model. NMR IN BIOMEDICINE 2008; 21:1102-1111. [PMID: 18780285 DOI: 10.1002/nbm.1287] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
Manganese has been used as a T(1)-weighted MRI contrast agent in a variety of applications. Because manganese ions (Mn(2+)) enter viable myocardial cells via voltage-gated Ca(2+) channels, manganese-enhanced MRI is sensitive to the viability and inotropic state of the heart. In spite of the established importance of Ca(2+) regulation in the heart both before and after myocardial injury, monitoring strategies to assess Ca(2+) homeostasis in affected cardiac tissues are limited. This study implements a T(1)-mapping method to obtain quantitative information both dynamically and over a range of MnCl(2) infusion doses. To optimize the current Mn(2+) infusion protocols, we performed both dose-dependent and temporal washout studies. A non-linear relationship between infused MnCl(2) solution dose and increase in left ventricular wall relaxation rate (DeltaR(1)) was observed. Control mice also exhibited significant Mn(2+) clearance over time, with a decrease in DeltaR(1) of approximately 50% occurring in just 2.5 h. The complicated efflux time dependence possibly suggests multiple efflux mechanisms. With the use of the measured relationship between infused Mn(2+) dose, DeltaR(1), and inductively coupled plasma mass spectrometry data analysis provided a means of estimating the absolute heart Mn concentration in vivo. We show that this technique has the sensitivity to observe or monitor potential alterations in Ca(2+) handling in vivo because of the physiological remodeling after myocardial infarction. Left ventricular free wall DeltaR(1) values were significantly lower (P = 0.005) in the adjacent zone, surrounding the injured myocardial tissue, than in healthy tissue. This inferred reduction in Mn concentration can be used to estimate potentially salvageable myocardium in vivo for future treatment or evaluation of disease progression.
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Affiliation(s)
- Ben Waghorn
- Small Animal Imaging, Department of Radiology, Medical College of Georgia, Augusta, GA 30912, USA
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Huang X, Moore DJ, Ketchum RJ, Nunemaker CS, Kovatchev B, McCall AL, Brayman KL. Resolving the conundrum of islet transplantation by linking metabolic dysregulation, inflammation, and immune regulation. Endocr Rev 2008; 29:603-30. [PMID: 18664617 PMCID: PMC2819735 DOI: 10.1210/er.2008-0006] [Citation(s) in RCA: 42] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Abstract
Although type 1 diabetes cannot be prevented or reversed, replacement of insulin production by transplantation of the pancreas or pancreatic islets represents a definitive solution. At present, transplantation can restore euglycemia, but this restoration is short-lived, requires islets from multiple donors, and necessitates lifelong immunosuppression. An emerging paradigm in transplantation and autoimmunity indicates that systemic inflammation contributes to tissue injury while disrupting immune tolerance. We identify multiple barriers to successful islet transplantation, each of which either contributes to the inflammatory state or is augmented by it. To optimize islet transplantation for diabetes reversal, we suggest that targeting these interacting barriers and the accompanying inflammation may represent an improved approach to achieve successful clinical islet transplantation by enhancing islet survival, regeneration or neogenesis potential, and tolerance induction. Overall, we consider the proinflammatory effects of important technical, immunological, and metabolic barriers including: 1) islet isolation and transplantation, including selection of implantation site; 2) recurrent autoimmunity, alloimmune rejection, and unique features of the autoimmune-prone immune system; and 3) the deranged metabolism of the islet transplant recipient. Consideration of these themes reveals that each is interrelated to and exacerbated by the other and that this connection is mediated by a systemic inflammatory state. This inflammatory state may form the central barrier to successful islet transplantation. Overall, there remains substantial promise in islet transplantation with several avenues of ongoing promising research. This review focuses on interactions between the technical, immunological, and metabolic barriers that must be overcome to optimize the success of this important therapeutic approach.
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Affiliation(s)
- Xiaolun Huang
- Department of Surgery, University of Virginia, Charlottesville, Virginia 22908, USA
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Lin M, Lubag A, McGuire MJ, Seliounine SY, Tsyganov EN, Antich PP, Sherry AD, Brown KC, Sun X. Advances in molecular imaging of pancreatic beta cells. FRONTIERS IN BIOSCIENCE : A JOURNAL AND VIRTUAL LIBRARY 2008; 13:4558-75. [PMID: 18508529 PMCID: PMC2790725 DOI: 10.2741/3023] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
The development of non-invasive imaging methods for early diagnosis of beta cell associated metabolic diseases, including type 1 and type 2 diabetes (T1D and T2D), has recently drawn interest from the molecular imaging community and clinical investigators. Due to the challenges imposed by the location of the pancreas, the sparsely dispersed beta cell population within the pancreas, and the poor understanding of the pathogenesis of the diseases, clinical diagnosis of beta cell abnormalities is still limited. Current diagnostic methods are invasive, often inaccurate, and usually performed post-onset of the disease. Advances in imaging techniques for probing beta cell mass and function are needed to address this critical health care problem. A variety of imaging techniques have been tested for the assessment of pancreatic beta cell islets. Here we discuss current advances in magnetic resonance imaging (MRI), bioluminescence imaging (BLI), and nuclear imaging for the study of beta cell diseases. Spurred by early successes in nuclear imaging techniques for beta cells, especially positron emission tomography (PET), the need for beta cell specific ligands has expanded. Progress for obtaining such ligands is presented. We report our preliminary efforts of developing such a peptidic ligand for PET imaging of pancreatic beta cells.
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Affiliation(s)
- Mai Lin
- Department of Radiology, University of Texas Southwestern Medical Center, 5323 Harry Hines Blvd., Dallas, Texas 75390, USA
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Sotak CH, Sharer K, Koretsky AP. Manganese cell labeling of murine hepatocytes using manganese(III)-transferrin. CONTRAST MEDIA & MOLECULAR IMAGING 2008; 3:95-105. [PMID: 18546093 PMCID: PMC3197774 DOI: 10.1002/cmmi.235] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Manganese(III)-transferrin [Mn(III)-Tf] was investigated as a way to accomplish manganese-labeling of murine hepatocytes for MRI contrast. It is postulated that Mn(III)-Tf can exploit the same transferrin-receptor-dependent and -independent metabolic pathways used by hepatocytes to transport the iron analog Fe(III)-Tf. More specifically, it was investigated whether manganese delivered by transferrin could give MRI contrast in hepatocytes. Comparison of the T1 and T2 relaxation times of Mn(III)-Tf and Fe(III)-Tf over the same concentration range showed that the r1 relaxivities of the two metalloproteins are the same in vitro, with little contribution from paramagnetic enhancement. The degree of manganese cell labeling following incubation for 2-7 h in 31.5 microm Mn(III)-Tf was comparable to that of hepatocytes incubated in 500 microm Mn2+ for 1 h. The intrinsic manganese tissue relaxivity between Mn(III)-Tf-labeled and Mn2+-labeled cells was found to be the same, consistent with Mn(III) being released from transferrin and reduced to Mn2+. For both treatment regimens, manganese uptake by hepatocytes appeared to saturate in the first 1-2 h of the incubation period and may explain why the efficiency of hepatocyte cell labeling by the two methods appeared to be comparable in spite of the approximately 16-fold difference in effective manganese concentration. Hepatocytes continuously released manganese, as detected by MRI, and this was the same for both Mn2+- and Mn(III)-Tf-labeled cells. Manganese release may be the result of normal hepatocyte function, much in the same way that hepatocytes excrete manganese into the bile in vivo. This approach exploits a biological process-namely receptor binding, endocytosis and endosomal acidification-to initiate the release of an MRI contrast agent, potentially conferring more specificity to the labeling process. The ubiquitous expression of transferrin receptors by eukaryotic cells should make Mn(III)-Tf particularly useful for manganese labeling of a wide variety of cells both in culture and in vivo.
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Affiliation(s)
- Christopher H Sotak
- Department of Biomedical Engineering, Worcester Polytechnic Institute, Worcester, MA 01609, USA.
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Imaging of islet grafts. Curr Opin Organ Transplant 2007. [DOI: 10.1097/mot.0b013e3282f19f31] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Braun RD, Gradianu M, Vistisen KS, Roberts RL, Berkowitz BA. Manganese-enhanced MRI of human choroidal melanoma xenografts. Invest Ophthalmol Vis Sci 2007; 48:963-7. [PMID: 17325133 PMCID: PMC3760708 DOI: 10.1167/iovs.06-1156] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
PURPOSE To test the hypothesis that the structure and function of an experimental human choroidal melanoma xenograft and neighboring non-tumor-bearing retina can be simultaneously assessed by using manganese-enhanced MRI (MEMRI). METHODS Spheroids grown from the human choroidal melanoma cell line C918 were implanted in the superior suprachoroidal space of 11 WAG/Nij-rnu nude rats. Two weeks later, MRI data were collected 4 hours after intraperitoneal injection of saline or MnCl(2), an MRI contrast agent that can act as a biomarker of cellular demand for ions, such as calcium. The following parameters were measured: (1) tumor signal intensity, (2) inner and outer retinal signal intensity in non-tumor-bearing inferior retina, and (3) whole and inner retinal thickness of inferior retina. Separate MEMRI experiments were performed on spheroids in vitro after MnCl(2) exposure and washing. RESULTS In vitro, spheroids exposed to MnCl(2) retained sufficient Mn(2+) to demonstrate contrast enhancement during MEMRI. In vivo, injection of MnCl(2) resulted in a 30% increase in tumor signal intensity compared with tumors in rats injected with saline (P < 0.05). In inferior retina of tumor-bearing eyes, outer retinal signal intensity increased by 17% relative to a similar region in control eyes (P < 0.05), but there was no change in the inferior inner retinal intensity. Total retinal thickness of the inferior retina in the tumor-bearing eyes increased by 8%, compared with that in the non-tumor-bearing eyes (P < 0.05). CONCLUSIONS The present identification of regions of enhanced Mn(2+) uptake in choroidal melanoma and a somewhat unexpected edema and increased outer retinal ion demand in neighboring non-tumor-bearing retina highlights MEMRI as a potentially powerful method for noninvasively monitoring tumor progression and treatment response and efficacy.
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Affiliation(s)
- Rod D Braun
- Department of Anatomy and Cell Biology, Wayne State University School of Medicine, Detroit, MI, USA.
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Abstract
The Edmonton trials have brought about a marked improvement in the short-term rate of success of islet transplantation with rates of insulin-independence of 80% at 1-year being reported by several institutions worldwide. Unfortunately, this rate consistently decreases to 10-15% by 5 years post-transplantation. Several mechanisms have been proposed to explain this apparent 'islet exhaustion', but are difficult to pinpoint in a given patient. Understanding the reasons for islet graft exhaustion and its kinetics is a prerequisite for the improvement of islet transplantation outcome. In this regard, efficient monitoring tools for the islet graft have been conspicuously lacking and are required to detect islet damage and diagnose its mechanisms in a timely fashion, so as to initiate salvage therapy such as antirejection treatment. Tools for the monitoring of the islet graft include follow-up of metabolic function but mostly indicate dysfunction when it is too late to take action. Progress is likely to arise in the fields of immune monitoring, molecular monitoring and islet imaging, notably thanks to magnetic resonance (MR) or positron emission tomography (PET) technologies.
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Affiliation(s)
- T Berney
- Cell Isolation and Transplantation Center, Division of Visceral and Transplant Surgery, Geneva University Hospitals, Geneva, Switzerland.
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