Electron Density of Adipose Tissues Determined by Phase-Contrast Computed Tomography Provides a Measure for Mitochondrial Density and Fat Content
Phase-contrast computed tomography (PCCT) is an X-ray-based imaging method measuring differences in the refractive index during tissue passage. While conventional X-ray techniques rely on the absorption of radiation due to differing tissue-specific attenuation coefficients, PCCT enables the determin...
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| Format: | Article |
| Language: | English |
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Frontiers Media S.A.
2018-06-01
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| Series: | Frontiers in Physiology |
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| Online Access: | https://www.frontiersin.org/article/10.3389/fphys.2018.00707/full |
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| author | Lorenz Birnbacher Stefanie Maurer Stefanie Maurer Katharina Scheidt Julia Herzen Franz Pfeiffer Franz Pfeiffer Franz Pfeiffer Tobias Fromme Tobias Fromme |
| author_facet | Lorenz Birnbacher Stefanie Maurer Stefanie Maurer Katharina Scheidt Julia Herzen Franz Pfeiffer Franz Pfeiffer Franz Pfeiffer Tobias Fromme Tobias Fromme |
| author_sort | Lorenz Birnbacher |
| collection | DOAJ |
| description | Phase-contrast computed tomography (PCCT) is an X-ray-based imaging method measuring differences in the refractive index during tissue passage. While conventional X-ray techniques rely on the absorption of radiation due to differing tissue-specific attenuation coefficients, PCCT enables the determination of the electron density (ED). By the analysis of respective phantoms and ex vivo specimens, we identified the components responsible for different electron densities in murine adipose tissue depots to be cellular fat and mitochondrial content, two parameters typically different between white adipose tissue (WAT) and brown adipose tissue (BAT). Brown adipocytes provide mammals with a means of non-shivering thermogenesis to defend normothermia in a cold environment. Brown adipocytes are found in dedicated BAT depots and interspersed within white fat depots, a cell type referred to as brite (brown in white) adipocyte. Localization and quantification of brown and brite adipocytes in situ allows an estimate of depot thermogenic capacity and potential contribution to maximal metabolic rate in the cold. We utilized PCCT to infer the composition of white, brite, and brown adipose tissue from ED of individual depots. As proof of principle, we imaged mice 10, 20, and 30 days of age. During this period, several WAT depots are known to undergo transient browning. Based on ED, classical WAT and BAT could be clearly distinguished. Retroperitoneal and inguinal WAT depots increased transiently in ED during the known remodeling from white to brite/brown and back to white. We systematically analyzed 18 anatomically defined adipose tissue locations and identified changes in fat content and mitochondrial density that imply an orchestrated pattern of simultaneous browning and whitening on the organismic level. Taken together, PCCT provides a three-dimensional imaging technique to visualize ED of tissues in situ. Within the adipose organ, ED provides a measure of mitochondrial density and fat content. Depending on experimental setting, these constitute surrogate markers of cellular distribution of white, brite, and brown adipocytes and thereby an estimate of thermogenic capacity. |
| first_indexed | 2024-12-23T06:17:04Z |
| format | Article |
| id | doaj.art-4276207af61a404a92cfcf38f41b1a62 |
| institution | Directory Open Access Journal |
| issn | 1664-042X |
| language | English |
| last_indexed | 2024-12-23T06:17:04Z |
| publishDate | 2018-06-01 |
| publisher | Frontiers Media S.A. |
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| spelling | doaj.art-4276207af61a404a92cfcf38f41b1a622022-12-21T17:57:16ZengFrontiers Media S.A.Frontiers in Physiology1664-042X2018-06-01910.3389/fphys.2018.00707347289Electron Density of Adipose Tissues Determined by Phase-Contrast Computed Tomography Provides a Measure for Mitochondrial Density and Fat ContentLorenz Birnbacher0Stefanie Maurer1Stefanie Maurer2Katharina Scheidt3Julia Herzen4Franz Pfeiffer5Franz Pfeiffer6Franz Pfeiffer7Tobias Fromme8Tobias Fromme9Biomedical Physics, Department of Physics and Munich School of BioEngineering, Technical University of Munich, Munich, GermanyChair of Molecular Nutritional Medicine, TUM School of Life Sciences, Technical University of Munich, Munich, GermanyElse Kröner-Fresenius Center for Nutritional Medicine, Technical University of Munich, Freising, GermanyBiomedical Physics, Department of Physics and Munich School of BioEngineering, Technical University of Munich, Munich, GermanyBiomedical Physics, Department of Physics and Munich School of BioEngineering, Technical University of Munich, Munich, GermanyBiomedical Physics, Department of Physics and Munich School of BioEngineering, Technical University of Munich, Munich, GermanyDepartment of Diagnostic and Interventional Radiology, Klinikum rechts der Isar, Technical University of Munich, Munich, GermanyInstitute for Advanced Study, Technical University of Munich, Munich, GermanyChair of Molecular Nutritional Medicine, TUM School of Life Sciences, Technical University of Munich, Munich, GermanyElse Kröner-Fresenius Center for Nutritional Medicine, Technical University of Munich, Freising, GermanyPhase-contrast computed tomography (PCCT) is an X-ray-based imaging method measuring differences in the refractive index during tissue passage. While conventional X-ray techniques rely on the absorption of radiation due to differing tissue-specific attenuation coefficients, PCCT enables the determination of the electron density (ED). By the analysis of respective phantoms and ex vivo specimens, we identified the components responsible for different electron densities in murine adipose tissue depots to be cellular fat and mitochondrial content, two parameters typically different between white adipose tissue (WAT) and brown adipose tissue (BAT). Brown adipocytes provide mammals with a means of non-shivering thermogenesis to defend normothermia in a cold environment. Brown adipocytes are found in dedicated BAT depots and interspersed within white fat depots, a cell type referred to as brite (brown in white) adipocyte. Localization and quantification of brown and brite adipocytes in situ allows an estimate of depot thermogenic capacity and potential contribution to maximal metabolic rate in the cold. We utilized PCCT to infer the composition of white, brite, and brown adipose tissue from ED of individual depots. As proof of principle, we imaged mice 10, 20, and 30 days of age. During this period, several WAT depots are known to undergo transient browning. Based on ED, classical WAT and BAT could be clearly distinguished. Retroperitoneal and inguinal WAT depots increased transiently in ED during the known remodeling from white to brite/brown and back to white. We systematically analyzed 18 anatomically defined adipose tissue locations and identified changes in fat content and mitochondrial density that imply an orchestrated pattern of simultaneous browning and whitening on the organismic level. Taken together, PCCT provides a three-dimensional imaging technique to visualize ED of tissues in situ. Within the adipose organ, ED provides a measure of mitochondrial density and fat content. Depending on experimental setting, these constitute surrogate markers of cellular distribution of white, brite, and brown adipocytes and thereby an estimate of thermogenic capacity.https://www.frontiersin.org/article/10.3389/fphys.2018.00707/fullphase-contrast computed tomographybrown adipose tissuewhite adipose tissuebrite adipocytebeige adipocyteelectron density |
| spellingShingle | Lorenz Birnbacher Stefanie Maurer Stefanie Maurer Katharina Scheidt Julia Herzen Franz Pfeiffer Franz Pfeiffer Franz Pfeiffer Tobias Fromme Tobias Fromme Electron Density of Adipose Tissues Determined by Phase-Contrast Computed Tomography Provides a Measure for Mitochondrial Density and Fat Content Frontiers in Physiology phase-contrast computed tomography brown adipose tissue white adipose tissue brite adipocyte beige adipocyte electron density |
| title | Electron Density of Adipose Tissues Determined by Phase-Contrast Computed Tomography Provides a Measure for Mitochondrial Density and Fat Content |
| title_full | Electron Density of Adipose Tissues Determined by Phase-Contrast Computed Tomography Provides a Measure for Mitochondrial Density and Fat Content |
| title_fullStr | Electron Density of Adipose Tissues Determined by Phase-Contrast Computed Tomography Provides a Measure for Mitochondrial Density and Fat Content |
| title_full_unstemmed | Electron Density of Adipose Tissues Determined by Phase-Contrast Computed Tomography Provides a Measure for Mitochondrial Density and Fat Content |
| title_short | Electron Density of Adipose Tissues Determined by Phase-Contrast Computed Tomography Provides a Measure for Mitochondrial Density and Fat Content |
| title_sort | electron density of adipose tissues determined by phase contrast computed tomography provides a measure for mitochondrial density and fat content |
| topic | phase-contrast computed tomography brown adipose tissue white adipose tissue brite adipocyte beige adipocyte electron density |
| url | https://www.frontiersin.org/article/10.3389/fphys.2018.00707/full |
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