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Abbas H, Broche LM, Ezdoglian A, Li D, Yuecel R, Ross PJ, Lurie DJ, Wilson HM, Dawson DK. 4324Fast-field cycling magnetic resonance detection of intracellular iron in the nanomolar range - A pre-requisite for in-vivo study of inflammation. Eur Heart J 2019. [DOI: 10.1093/eurheartj/ehz745.0161] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
Abstract
Background
Ultra-small superparamagnetic iron oxide (USPIO) nanoparticles are phagocytosed by macrophages and when subjected to magnetic resonance imaging (MRI) detect inflammation. We describe a novel MR technique where the magnetic field is rapidly cycled (Fast field-cycling MR, FFC-MR), assessing T1 dispersion over a range of low (100μT-0.2T) fields and offering superior T1-based iron quantification.
AIM
To quantify iron using the FFC-MR R1 (1/T1) dispersion profile and flow cytometry features of USPIO-laden cells, in comparison to colorimetric assays.
Methods
Murine J774 macrophage-like cells were incubated with 0–200μg/ml Fe as USPIO (ferumoxytol) for 16 hours, washed and suspended in 500μl PBS/2mM EDTA. Prussian blue staining confirmed USPIO phagocytosis. Relaxation was measured using a clinical, in-house built prototype 0.2T FFC-MR system with a custom test tube coil. R1 dispersion was derived from a saturation recovery sequence (Fig. 1A). R1 (s–1) values were calculated with a monoexponential curve fitting algorithm, R2 of fits were ≥0.999. R1 dispersion profiles were generated plotting R1 against the magnetic field (T). Quantification of side scatter (SCC) intensity and the USPIO-occupied fraction of total cell area was performed with imaging flow cytometry. A colorimetric assay provided validation of cell iron content. All data are mean±SEM, analysed with t-tests, Pearson correlation and linear regression; statistical significance set at p<0.05.
Results
Table 1 shows quantitative data derived by all 3 modalities with increasing USPIO exposure. FFC-MR detection of intracellular iron was excellent (p≤0.001 vs. control for all), with separation of average R1 dispersion profiles (Fig. 1B), strong correlation with colorimetry (r=0.993 p<0.001) and good fit on linear regression model (R2=0.9222, Fig 1C). Flow cytometry quantification of SCC was comparable (p≤0.001 for all), whereas USPIO-occupied area was only sensitive at exposures ≥10μg/ml USPIO (r=0.967 p<0.001 & r=0.983 p<0.001 vs. colorimetric respectively). FFC-MR detected iron at ≥1.12ng/μg protein.
USPIO exposure (μg/ml medium) 0 5 10 40 80 100 200 FFC-MR Mean R1 1x106 cell suspension (s–1) 0.308±0.014 0.356±0.013** 0.432±0.016** 0.706±0.021** 1.174±0.031** 1.239±0.033** 1.599±0.041** Flow cytometry USPIO area/cell area 0.034±0.001 0.036±0.001 0.037±0.001* 0.069±0.001** 0.085±0.001** 0.090±0.001** 0.097±0.001** Flow cytometry SSC intensity 26860 32815** 39573** 69285** 80967** 82693** 86373** Colorimetric assay Iron concentration 1x106 cells (ng/μg protein) 0.115±0.118 1.121±0.045** 2.074±0.084** 5.496±0.134** 8.421±0.269** 9.771±0.100** 12.398±0.233** SSC = side-scattered light; *p<0.05 vs. control; **p<0.001 vs. control.
Conclusion
Field-cycling MR is capable of highly accurate intracellular USPIO quantification, which has potential to non-invasively detect clinically relevant amounts of iron in inflammatory cardiovascular diseases.
Acknowledgement/Funding
NHS Grampian Endowment Fund
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Affiliation(s)
- H Abbas
- University of Aberdeen, Aberdeen Cardiovascular and Diabetes Centre, Aberdeen, United Kingdom
| | - L M Broche
- University of Aberdeen, Dept. of Bio-medical Physical, Aberdeen, United Kingdom
| | - A Ezdoglian
- University of Aberdeen, Iain Fraser Cytometry Centre, Institute of Medical Sciences, Aberdeen, United Kingdom
| | - D Li
- University of Aberdeen, Iain Fraser Cytometry Centre, Institute of Medical Sciences, Aberdeen, United Kingdom
| | - R Yuecel
- University of Aberdeen, Iain Fraser Cytometry Centre, Institute of Medical Sciences, Aberdeen, United Kingdom
| | - P J Ross
- University of Aberdeen, Dept. of Bio-medical Physical, Aberdeen, United Kingdom
| | - D J Lurie
- University of Aberdeen, Dept. of Bio-medical Physical, Aberdeen, United Kingdom
| | - H M Wilson
- University of Aberdeen, Aberdeen Cardiovascular and Diabetes Centre, Aberdeen, United Kingdom
| | - D K Dawson
- University of Aberdeen, Aberdeen Cardiovascular and Diabetes Centre, Aberdeen, United Kingdom
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Collins C, Hall M, Bruno D, Sokolowska J, Duncan L, Yuecel R, McCarthy U, Fordyce MJ, Pert CC, McIntosh R, MacKay Z. Generation of Paramoeba perurans clonal cultures using flow cytometry and confirmation of virulence. J Fish Dis 2017; 40:351-365. [PMID: 27524425 DOI: 10.1111/jfd.12517] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/22/2016] [Revised: 05/18/2016] [Accepted: 05/24/2016] [Indexed: 06/06/2023]
Abstract
Amoebic gill disease (AGD) in farmed Atlantic salmon is caused by the amoeba Paramoeba perurans. The recent establishment of in vitro culture techniques for P. perurans has provided a valuable tool for studying the parasite in detail. In this study, flow cytometry was used to generate clonal cultures from single-sorted amoeba, and these were used to successfully establish AGD in experimental Atlantic salmon. The clonal cultures displayed differences in virulence, based on gill scores. The P. perurans load on gills, determined by qPCR analysis, showed a positive relationship with gill score, and with clonal virulence, indicating that the ability of amoebae to proliferate and/or remain attached on gills may play a role in virulence. Gill scores based on gross signs and histopathological analysis were in agreement. No association between level of gill score and specific gill arch was observed. It was found that for fish with lower gill scores based on histopathological examination, gross examination and qPCR analysis of gills from the same fish were less successful in detecting lesions and amoebae, respectively.
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Affiliation(s)
- C Collins
- Marine Laboratory, Marine Scotland, Aberdeen, UK
| | - M Hall
- Marine Laboratory, Marine Scotland, Aberdeen, UK
| | - D Bruno
- Marine Laboratory, Marine Scotland, Aberdeen, UK
| | - J Sokolowska
- Marine Laboratory, Marine Scotland, Aberdeen, UK
| | - L Duncan
- Iain Fraser Cytometry Centre, Institute of Medical Sciences, School of Medicine & Dentistry, University of Aberdeen, Aberdeen, UK
| | - R Yuecel
- Iain Fraser Cytometry Centre, Institute of Medical Sciences, School of Medicine & Dentistry, University of Aberdeen, Aberdeen, UK
| | - U McCarthy
- Marine Laboratory, Marine Scotland, Aberdeen, UK
| | - M J Fordyce
- Marine Laboratory, Marine Scotland, Aberdeen, UK
| | - C C Pert
- Marine Laboratory, Marine Scotland, Aberdeen, UK
| | - R McIntosh
- Marine Laboratory, Marine Scotland, Aberdeen, UK
| | - Z MacKay
- Marine Laboratory, Marine Scotland, Aberdeen, UK
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