Increased elastin content and decreased elastin concentration may be predisposing factors in dissecting aneurysms of human thoracic aorta

Ma, Cattell; Ps, Hasleton; Jc, Anderson

doi:10.1093/cvr/27.2.176

Cited by 26 publications

(18 citation statements)

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“…16–19,31,33 We also discovered altered AAU for elastin, which implies altered percentage of RAD-oriented elastin in regions N and R among patients with BAV-ATAA and TAV-ATAA. The decreased AAU and subsequently decreased percentage of RAD-oriented elastin in regions N and R of BAV-ATAA could be due to remodeling of elastin fiber microarchitecture despite a total elastin content in ATAA tissue that is unchanged irrespective of age or aortic valve morphology 4,34 and given the extremely low turnover rate of elastin in adults.…”

Section: Discussionmentioning

confidence: 75%

Extracellular matrix fiber microarchitecture is region-specific in bicuspid aortic valve-associated ascending aortopathy

Tsamis

Phillippi

Koch

et al. 2016

The Journal of Thoracic and Cardiovascular Surgery

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Objective Ascending thoracic aortic aneurysm (ATAA) in patients with bicuspid aortic valve (BAV) commonly dilate asymmetrically compared with patients with tricuspid aortic valve (TAV). This discrepancy in aneurysm geometry led us to hypothesize that microarchitectural differences underlie the observed asymmetric dilatation pattern. The purpose of this study was to characterize the microarchitectural distinctions of the extracellular matrix of the 2 phenotypes with a focus on the proportion of radially oriented elastin and collagen fibers in different circumferential aortic regions. Methods Aortic tissue rings were obtained just distal to the sinotubular junction from patients with BAV or TAV undergoing elective aneurysm repair. They were sectioned into three circumferentially based regions according to adjacent aortic sinus segment (left coronary sinus [L], right coronary sinus [R], or noncoronary sinus [N]). Multiphoton microscopy was used to quantify and characterize the number of radially oriented elastin and collagen fibers. Results There were fewer radially oriented fibers in medial region N and medial-intimal region R of BAV-ATAAs when compared with TAV-ATAAs (medial region N, amplitude of angular undulation of elastin = 10.67° ± 1.35° vs 15.58° ± 1.91°; P = .041; medial-intimal region R, amplitude of angular undulation of elastin = 9.83° ± 0.83° vs 14.72° ± 1.64°; P = .015). Conversely, fibers became more radially oriented in the medial-intimal region L of BAV-ATAA when compared with TAV-ATAA (amplitude of angular undulation of collagen = 18.67° ± 0.95° vs 14.56° ± 1.37°; P = .041). Conclusions The differential pattern of fiber orientation noted between L and N-R regions help explain the unique pattern of greater curvature dilatation of BAV-ATAA. The distinctions noted in matrix microarchitecture may form the basis of differing aneurysm geometries and aortic wall integrities in ATAAs arising in these different valve morphologies.

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Section: Discussionmentioning

confidence: 75%

Extracellular matrix fiber microarchitecture is region-specific in bicuspid aortic valve-associated ascending aortopathy

Tsamis

Phillippi

Koch

et al. 2016

The Journal of Thoracic and Cardiovascular Surgery

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“…Also, it has been previously reported that the total elastin content remained unchanged in ATA dissection (Cattell et al, 1993; de Figueiredo Borges et al, 2008; Nakashima et al, 1990a; Nakashima et al, 1990b; Sariola et al, 1986; Wang et al, 2005) and in CTRL-ATA (Andreotti et al, 1985) with increasing age, but elastin concentration has been shown to be decreased in CTRL-ATA with increasing age (Halme et al, 1985; Hosoda et al, 1984; Wang et al, 2005). …”

Section: Discussionmentioning

confidence: 87%

Fiber micro-architecture in the longitudinal-radial and circumferential-radial planes of ascending thoracic aortic aneurysm media

Tsamis

Phillippi

Koch

et al. 2013

Journal of Biomechanics

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It was recently demonstrated by our group that the delamination strength of ascending thoracic aortic aneurysms (ATAA) was lower than that of control (CTRL, non-aneurysmal) ascending thoracic aorta (ATA), and the reduced strength was more pronounced among bicuspid (BAV) vs. tricuspid aortic valve (TAV) patients, suggesting a different risk of aortic dissection for BAV patients. We hypothesized that aortic valve morphologic phenotype predicts fiber micro-architectural anomalies in ATA. To test the hypothesis, we characterized the micro-architecture in the longitudinal-radial (Z-RAD) and circumferential-radial (Θ-RAD) planes of human ATA tissue that was artificially dissected medially. The outer and inner-media of CTRL-ATA, BAV-ATAA and TAV-ATAA were imaged using multi-photon microscopy in the Z-RAD and Θ-RAD planes to observe collagen and elastin. Micrographs were processed using an image-based tool to quantify several micro-architectural characteristics. In the outer-media of BAV-ATAA, elastin was more undulated and less aligned about the Θ-axis when compared with CTRL-ATA, which is consistent with increased tensile stretch at inflection point of Θ-strips of adventitial-medial half of BAV-ATAA (1.28) when compared with CTRL-ATA (1.13). With increasing age, collagen became more undulated about the Z-axis within the outer-media of TAV-ATAA, and elastin became more oriented in the Z-axis and collagen less radially-oriented within the inner-media of TAV-ATAA. This discrepancy in the micro-architecture with fibers in the inner layers being more stretched and with disrupted radially-oriented components than fibers in the outer layers may be associated with the development, progression and vascular remodeling in aneurysms arising in TAV patients.

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“…Smooth muscle cells and a rich extracellular matrix, principally composed of collagen and elastin fibers, are the most important components of this layer. These proteins are directly implicated in the aneurismal development and are modified, structurally and quantitatively, during the advent of this aortic pathology [13][14][15].…”

Section: Resultsmentioning

confidence: 99%

FTIR protein secondary structure analysis of human ascending aortic tissues

Bonnier

Rubin

Debelle

et al. 2008

Journal of Biophotonics

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Journal of BIOPHOTONICSThe advent of moderate dilatations in ascending aortas is often accompanied by structural modifications of the main components of the aortic tissue, elastin and collagen. In this study, we have undertaken an approach based on FTIR microscopy coupled to a curve-fitting procedure to analyze secondary structure modifications in these proteins in human normal and pathological aortic tissues. We found that the outcome of the aortic pathology is strongly influenced by these proteins, which are abundant in the media of the aortic wall, and that the advent of an aortic dilatation is generally accompanied by a decrease of parallel b-sheet structures. Elastin, essentially composed of b-sheet structures, seems to be directly related to these changes and therefore indicative of the elastic alteration of the aortic wall. Conventional microscopy and confocal fluorescence microscopy were used to compare FTIR microscopy results with the organization of the elastic fibers present in the tissues. This in-vitro study on 6 patients (three normal and three pathologic), suggests that such a spectroscopic marker, specific to aneurismal tissue characterization, could be important information for surgeons who face the dilemma of moderate aortic tissue dilatation of the ascending aortas.Infrared spectroscopy and imaging was applied to analyse Human thoracic ascending aortas with the aim to highlight the protein secondary structure reorganisation after an aneurism outcome. We used a curve-fitting procedure to visualise modifications in the protein spectral profile where alteration of b structures in pathological aortas could be detected. Our spectroscopic observations on tissue sections corroborated with confocal fluorescence microscopy clearly demonstrating that elastic fibres of aortic wall are strongly altered. Elastin appears as the privileged target during the pathological process.

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Increased elastin content and decreased elastin concentration may be predisposing factors in dissecting aneurysms of human thoracic aorta

Abstract: Biochemical changes in dissections are localised to the dissected area, with increased deposition of elastin, collagen, and other proteins. The altered matrix composition is likely to change the mechanical properties, possibly increasing the tendency to rupture.

Cited by 26 publications

References 0 publications

Extracellular matrix fiber microarchitecture is region-specific in bicuspid aortic valve-associated ascending aortopathy

Extracellular matrix fiber microarchitecture is region-specific in bicuspid aortic valve-associated ascending aortopathy

Fiber micro-architecture in the longitudinal-radial and circumferential-radial planes of ascending thoracic aortic aneurysm media

FTIR protein secondary structure analysis of human ascending aortic tissues

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