Skip to main page content
U.S. flag

An official website of the United States government

Dot gov

The .gov means it’s official.
Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

Https

The site is secure.
The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

Access keys NCBI Homepage MyNCBI Homepage Main Content Main Navigation
. 2018 Nov 15;8(21):6038-6052.
doi: 10.7150/thno.26598. eCollection 2018.

MicroCT imaging reveals differential 3D micro-scale remodelling of the murine aorta in ageing and Marfan syndrome

Júlia López-Guimet  1 , Lucía Peña-Pérez  2   3 , Robert S Bradley  4   5 , Patricia García-Canadilla  2 , Catherine Disney  6 , Hua Geng  6 , Andrew J Bodey  7 , Philip J Withers  4 , Bart Bijnens  2   8 , Michael J Sherratt  6 , Gustavo Egea  1   9   10
Affiliations

MicroCT imaging reveals differential 3D micro-scale remodelling of the murine aorta in ageing and Marfan syndrome

Júlia López-Guimet et al. Theranostics. .

Abstract

Aortic wall remodelling is a key feature of both ageing and genetic connective tissue diseases, which are associated with vasculopathies such as Marfan syndrome (MFS). Although the aorta is a 3D structure, little attention has been paid to volumetric assessment, primarily due to the limitations of conventional imaging techniques. Phase-contrast microCT is an emerging imaging technique, which is able to resolve the 3D micro-scale structure of large samples without the need for staining or sectioning. Methods: Here, we have used synchrotron-based phase-contrast microCT to image aortae of wild type (WT) and MFS Fbn1C1039G/+ mice aged 3, 6 and 9 months old (n=5). We have also developed a new computational approach to automatically measure key histological parameters. Results: This analysis revealed that WT mice undergo age-dependent aortic remodelling characterised by increases in ascending aorta diameter, tunica media thickness and cross-sectional area. The MFS aortic wall was subject to comparable remodelling, but the magnitudes of the changes were significantly exacerbated, particularly in 9 month-old MFS mice with ascending aorta wall dilations. Moreover, this morphological remodelling in MFS aorta included internal elastic lamina surface breaks that extended throughout the MFS ascending aorta and were already evident in animals who had not yet developed aneurysms. Conclusions: Our 3D microCT study of the sub-micron wall structure of whole, intact aorta reveals that histological remodelling of the tunica media in MFS could be viewed as an accelerated ageing process, and that phase-contrast microCT combined with computational image analysis allows the visualisation and quantification of 3D morphological remodelling in large volumes of unstained vascular tissues.

Keywords: Marfan syndrome; ageing; aorta; elastic lamella; microCT.

PubMed Disclaimer

Conflict of interest statement

Competing Interests: The authors have declared that no competing interest exists.

Figures

Figure 1
Figure 1
Image processing steps for aorta microCT scans. (A) Volumetric rendering of aorta scan from the aortic root to descending thoracic aorta. The blue box includes a slice stack of the ascending aorta indicated in B. (B) Representation of the stack made of 200 transverse slices from the ascending aortic wall. Red line traces the luminal surface and green line the media-adventitia limit. (C) Volumetric rendering of the 200 slices from the ascending aorta stack (blue box in (A)). Scissors represent the virtual opening process performed by the code. (D) IEL luminal surface example obtained after the virtual opening of the ascending aorta. (E) Display of the histological parameters quantified in the transverse aortic slices. Scale bars in (D-E), 100 µm.
Figure 2
Figure 2
Synchrotron-based microCT scan examples of wild type and Marfan syndrome mice aortae. (A) Wild-type aorta volumetric rendering. (B) Transverse slice of wild-type aorta corresponding to the yellow line in (A). (C) Volumetric rendering of a Marfan aorta with a non-dilated (yellow line) and a dilated (purple line) zones. (D) Transverse slice of the Marfan aorta at the non-dilated zone (yellow line in (C)). (E) Transverse slice of the Marfan aorta at the dilated zone (purple line in (C)). (F-H) Representative transverse sections from microCT scans of 9 month-old wild type and Marfan mice aortae (dilated and non-dilated zones). Scale bars in (B, D-E, H), 100 µm.
Figure 3
Figure 3
Transverse histological parameters in aged wild type and Marfan syndrome mice. (A) Ascending aorta luminal diameter (unpressurised). (B) Tunica media thickness mean values of each aorta. (C) Frequency distribution of the 200 thickness values per aorta. (D) Tunica media cross-sectional area. (E) Tunica media area occupied by lamellae. (F) Tunica media area occupied by the interlamellar space. (G) Tunica media percentage composition. WT: wild-type mice; MFS: Marfan syndrome mice. Results are mean ± SD. Continuous line corresponds to a mean statistical test, and dashed line to a dispersion statistical test.
Figure 4
Figure 4
Representative transverse sections from microCT scans of wild-type and Marfan syndrome mice aortae at 3, 6 and 9 months old. IEL: internal elastic lamina. Scale bar, 100 µm.
Figure 5
Figure 5
Transverse histological parameters in dilated and non-dilated aged Marfan syndrome mice aortae. Anatomically evident MFS dilated aortic zones were categorized separately (purple data here, and purple line in Figure 2), resulting in MFS 9 mo with n=2, and therefore no statistical comparisons were performed with this group. (A) Ascending aorta luminal diameter (unpressurised). (B) Tunica media thickness mean values. (C) Tunica media cross-sectional area. (D) Tunica media area occupied by lamellae. (E) Tunica media area occupied by the interlamellar space. (F) Tunica media percentage composition. WT: wild-type mice; MFS: Marfan syndrome mice. Results are mean ± SD.
Figure 6
Figure 6
2D and 3D visualisation of lamellae breaks progression in the tunica media of a Marfan syndrome aorta. (A) Transverse slices sequence of Marfan mice aortic wall. The yellow box marks the same break progressing both axially and laterally. In the beginning, there is a break in one or two lamellae, whose damage gradually worsens, affecting several neighbouring lamellae (slice 140) and the IEL (slices 240 to 300). (B-C) Volumetric rendering of the same aortic wall piece shown in (A) viewed laterally (B) or en-face (C). Here, only lamellae of the tunica media are rendered. Notice the extension and depth of the break, and the impact to multiple lamellae to different extents. Scale bar, 50 µm.
Figure 7
Figure 7
Ascending aorta IEL luminal surface analysis of aged wild type and Marfan syndrome mice aortae. (A) Representative images of the ascending aorta IEL surface. (B) Percentage of IEL surface occupied by breaks. (C) Percentage of the IEL surface occupied by breaks once Marfan 9 mo aortae were categorised into dilated (MFS dilated) or non-dilated (MFS 9 mo). WT: wild-type mice; MFS: Marfan syndrome mice. Results are mean ± SD. Continuous line corresponds to a mean statistical test, and dashed line to a dispersion statistical test. Scale bar, 200 µm.
See this image and copyright information in PMC

Similar articles

See all similar articles

Cited by

References

    1. Cheng JK, Wagenseil JE. Extracellular matrix and the mechanics of large artery development. Biomech Model Mechanobiol. 2012;11:1169–86. - PMC - PubMed
    1. Robertson AM, Watton PN. Mechanobiology of the arterial wall. In: Becker S, Kuznetsov A, editors. Transport in Biological Media. 1st ed. Elsevier; 2013. pp. 275–7.
    1. Wagenseil JE, Mecham RP. Vascular extracellular matrix and arterial mechanics. Physiol Rev. 2009;89:957–89. - PMC - PubMed
    1. Dietz HC, Loeys B, Carta L, Ramirez F. Recent progress towards a molecular understanding of Marfan syndrome. Am J Genet Part C Sem Med Gent. 2005;139C:4–9. - PubMed
    1. Wu D, Shen YH, Rusell L, Coselli JS, LeMaire SA. Molecular mechanisms of thoracic aortic dissection. J Surg Res. 2013;184:907–24. - PMC - PubMed

Publication types