Assessment of the aortic wall histological changes with ageing

Abstract

Aim: The authors aimed to quantitatively assess the variation with age of three of the main components of the aortic wall, namely elastic fibers (FE) and collagen fibers [FC(COL)], and smooth muscle cells (SMCs).

Materials and methods: Four aortic cross sections (base, cross, thoracic, abdominal) were collected during autopsy from 90 cases of all ages, processed using the classical histopathological (HP) technique (formalin fixation and paraffin embedding) and stained with Orcein and Goldner's trichrome. The obtained histological slides were transformed into virtual slides. Quantitative measurements of the three components were made on identical regions of interest (ROIs) selected from two-paired slides stained with the above-mentioned techniques using custom-made software, developed in MATLAB (MathWorks, USA).

Results and discussions: FE revealed an obvious decreasing general trend with age, present at all four levels of investigation. Smooth muscle fibers (FM) density showed almost no variation with age regardless of the level at which the measurement was made. FC(COL) density had an obvious increasing trend with age, expressed in all four aortic regions FE densities and FM densities were higher in men than in women, while FC(COL) densities were higher in women than in men in three of the aortic regions excepting, in all cases, the cross region.

Conclusions: There were differences between men and women concerning the composition of aortic wall cellular and extracellular compartments. FE and FC(COL) dominated the age-related remodeling process of the aortic wall. The process evolved in the same way in all regions of the aorta. Studies need to be continued to define more clearly this complex process of vascular wall remodeling with aging.

Figure 1

Sites of sampling. Modified after [23,24]

Figure 2

Windows of Aperio ImageScope program: (a) Selection of areas for measurement of different fibrillary components of aortic wall: HE (up), Orcein (middle) and Goldner’s trichrome (bottom) staining, ×0.6; (b) Detail – areas selected for elastic fibers measurement (left) stained with Orcein and smooth muscle fibers and collagen fibers stained with Goldner’s trichrome (right), ×20. HE: Hematoxylin–Eosin

Figure 3

Image processing of Orcein staining regions of interest (ROIs): (a) Original image; (b) Pre-processed image; (c) Background selection; (d) Saturation; (e) Resulted percentage of Orcein-stained material (dark blue) – 0.6 (60%)

Figure 4

Image processing for Goldner’s trichrome staining regions of interest (ROIs): (a) Original image; (b) Pre-processed image; (c) Background selection; (d) Saturation; (e) Resulted percentage of smooth muscle fibers (red stained material) – 0.13 (13%)

Figure 5

Age distribution related to sex. AV: Mean value; MAX: Highest value; MIN: Lowest value; STDEV: Standard deviation

Figure 6

Distribution on age periods (APs) related to sex. F: Female; M: Male; WG: Whole group

Figure 7

Correlation between different types of fibers and age at the four aortic topographical levels. 01_B: Cross section at the aortic base level; 02_C: Cross section at the aortic cross level; 03_T: Cross section at the thoracic aorta level; 04_Ab: Cross section at the abdominal aorta level; COL: Collagen fibers; FE: Elastic fibers; FM: Smooth muscle fibers; V: Age

Figure 8

Correlation between different types of fibers and sex at the four aortic topographical levels. 1_B: Cross section at the aortic base level; 2_C: Cross section at the aortic cross level; 3_T: Cross section at the thoracic aorta level; 4_Ab: Cross section at the abdominal aorta level; F: Female; FC: Collagen fibers; FE: Elastic fibers; FM: Smooth muscle fibers; M: Male

Figure 9

Distribution with age of whole values and mean values of elastic fibers (FE) percentages at the four aortic topographical levels. 01_B: Cross section at the aortic base level; 02_C: Cross section at the aortic cross level; 03_T: Cross section at the thoracic aorta level; 04_Ab: Cross section at the abdominal aorta level; AP: Age period

Figure 10

Distribution with age of whole values and mean values of smooth muscle fibers (FM) percentages at the four aortic topographical levels. 01_B: Cross section at the aortic base level; 02_C: Cross section at the aortic cross level; 03_T: Cross section at the thoracic aorta level; 04_Ab: Cross section at the abdominal aorta level; AP: Age period

Figure 11

Distribution with age of whole values and mean values of collagen fibers (FC) percentages at the four aortic topographical levels. 01_B: Cross section at the aortic base level; 02_C: Cross section at the aortic cross level; 03_T: Cross section at the thoracic aorta level; 04_Ab: Cross section at the abdominal aorta level; AP: Age period

Figure 12

Correlation with age of the FE/COL ratio at the four aortic topographical levels. 01_B: Cross section at the aortic base level; 02_C: Cross section at the aortic cross level; 03_T: Cross section at the thoracic aorta level; 04_Ab: Cross section at the abdominal aorta level; COL: Collagen fibers; FE: Elastic fibers; V: Age

Figure 13

Correlation with age of the FM/COL ratio at the four aortic topographical levels. 01_B: Cross section at the aortic base level; 02_C: Cross section at the aortic cross level; 03_T: Cross section at the thoracic aorta level; 04_Ab: Cross section at the abdominal aorta level; COL: Collagen fibers; FM: Smooth muscle fibers; V: Age

Figure 14

Correlation with age of the FE/FM ratio at the four aortic topographical levels. 01_B: Cross section at the aortic base level; 02_C: Cross section at the aortic cross level; 03_T: Cross section at the thoracic aorta level; 04_Ab: Cross section at the abdominal aorta level; FE: Elastic fibers; FM: Smooth muscle fibers; V: Age