Circumferential variations of mechanical behavior of the porcine thoracic aorta during the inflation test

Kim, Jungsil; Baek, Seungik

doi:10.1016/j.jbiomech.2011.04.022

Cited by 76 publications

(70 citation statements)

References 42 publications

(49 reference statements)

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“…It is emphasized that z depends on the orientation through the collagen orientation vector N, and similar collagen-stretch-based stimuli have been proposed earlier in the literature [6,7,[12][13][14]. In contrast, other stimuli such as stress [8][9][10][11] and the ratio between systolic and diastolic stretches [54] have also been suggested.…”

Section: Sensing Mechanismmentioning

confidence: 77%

Turnover of fibrillar collagen in soft biological tissue with application to the expansion of abdominal aortic aneurysms

Martufi

Gasser

2012

J. R. Soc. Interface.

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A better understanding of the inherent properties of vascular tissue to adapt to its mechanical environment is crucial to improve the predictability of biomechanical simulations. Fibrillar collagen in the vascular wall plays a central role in tissue adaptation owing to its relatively short lifetime. Pathological alterations of collagen turnover may fail to result in homeostasis and could be responsible for abdominal aortic aneurysm (AAA) growth at later stages of the disease. For this reason our previously reported multiscale constitutive framework (Martufi, G. & Gasser, T. C. 2011 J. Biomech . 44 , 2544–2550 ( doi:10.1016/j.jbiomech.2011.07.015 )) has been enriched by a collagen turnover model. Specifically, the framework's collagen fibril level allowed a sound integration of vascular wall biology, and the impact of collagen turnover on the macroscopic properties of AAAs was studied. To this end, model parameters were taken from the literature and/or estimated from clinical follow-up data of AAAs (on average 50.7 mm-large). Likewise, the in vivo stretch of the AAA wall was set, such that 10 per cent of collagen fibres were engaged. Results showed that the stretch spectrum, at which collagen fibrils are deposed, is the most influential parameter, i.e. it determines whether the vascular geometry grows, shrinks or remains stable over time. Most importantly, collagen turnover also had a remarkable impact on the macroscopic stress field. It avoided high stress gradients across the vessel wall, thus predicted a physiologically reasonable stress field. Although the constitutive model could be successfully calibrated to match the growth of small AAAs, a rigorous validation against experimental data is crucial to further explore the model's descriptive and predictive capabilities.

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Section: Sensing Mechanismmentioning

confidence: 77%

Turnover of fibrillar collagen in soft biological tissue with application to the expansion of abdominal aortic aneurysms

Martufi

Gasser

2012

J. R. Soc. Interface.

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“…An elevated blood pressure also creates increased circumferential stretch on the vessel wall perpendicular to the direction of blood flow [21,22] (figure 1). Chronic hypertension imposes higher pressure on the vessel wall and induces compensatory vascular remodelling.…”

Section: Introductionmentioning

confidence: 99%

Role of shear stress and stretch in vascular mechanobiology

Kassab

2011

J. R. Soc. Interface.

257

189

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Blood vessels are under constant mechanical loading from blood pressure and flow which cause internal stresses (endothelial shear stress and circumferential wall stress, respectively). The mechanical forces not only cause morphological changes of endothelium and blood vessel wall, but also trigger biochemical and biological events. There is considerable evidence that physiologic stresses and strains (stretch) exert vasoprotective roles via nitric oxide and provide a homeostatic oxidative balance. A perturbation of tissue stresses and strains can disturb biochemical homeostasis and lead to vascular remodelling and possible dysfunction (e.g. altered vasorelaxation, tone, stiffness, etc.). These distinct biological endpoints are caused by some common biochemical pathways. The focus of this brief review is to point out some possible commonalities in the molecular pathways in response to endothelial shear stress and circumferential wall stretch.

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“…The stress distribution may vary round the circumference of the porcine thoracic aorta, as demonstrated by Kim and Baek (2011). However, the stress distribution and stiffness differ between the circumferential regions only at higher stresses, where the stretched unwoven collagen fibers are mostly responsible for mechanical behavior of the wall.…”

Section: Relevance Of the Results To The Biomechanicsmentioning

confidence: 98%

“…The outer tunica adventitia contains vasa and nervi vasorum embedded within dense or loose collagen connective tissue. The incorporation of extracellular matrix (proteoglycans) and fibers (particularly elastin and collagen) into the network of smooth muscle and connective tissue cells provides nonlinear elasticity and distributes the tensile stresses (Shadwick 1999), as well as the deformation of the aortic wall (Lillie et al 2012;Kim and Baek 2011). Although the aorta shares the basic histological and biomechanical design of other arteries, it is the largest elastic artery of the mammalian body.…”

Section: Introductionmentioning

confidence: 99%

Segmental differences in the orientation of smooth muscle cells in the tunica media of porcine aortae

Tonar

Kochová

Cimrman

et al. 2014

Biomech Model Mechanobiol

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The orientation of vascular smooth muscle cells of porcine aortae was assessed to test the widely accepted assumption that these smooth muscle cells are arranged in two helices. We used tangential histological sections of 82 samples of five anatomical segments of thoracic and abdominal porcine aortae and three age groups in animals ranging in age from 5 to 210 days. The distribution of the orientation of smooth muscle cell nuclei in five proximodistal segments of the porcine aortae was determined using an algorithm that fitted a mixture of one to five von Mises probability distributions of the data retrieved from histological micrographs. Automated tracking of the nuclei was confirmed by and consistent with manual histological analysis. The orientation of the vascular smooth muscle cells was successfully fitted using two von Mises distributions in most of the samples with different ages, wall thicknesses, and anatomical positions, which corresponds to two populations of vascular smooth muscle cells. A minor fraction of samples also required a tertiary von Mises distribution to describe the orientation of the smooth muscle cell nuclei. The distribution of vascular smooth muscle cells in five aortic segments ranging from the thoracic ascending aorta to the abdominal intrarenal aorta exhibited similar main directions but different shapes. These results are consistent with the widely used model of two muscular helices intermingling in the arterial wall. Furthermore, we calculated the central angles of symmetry and the mean value of angles between the two assumed smooth muscle directions. We also successfully approximated the orientation of the smooth muscle cells using a mixture of von Mises distributions and our open-source software named dist_mixtures. This method is openly available to researchers who are interested in mathematically assessing the orientation of cell nuclei in various tissues.

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Circumferential variations of mechanical behavior of the porcine thoracic aorta during the inflation test

Cited by 76 publications

References 42 publications

Turnover of fibrillar collagen in soft biological tissue with application to the expansion of abdominal aortic aneurysms

Turnover of fibrillar collagen in soft biological tissue with application to the expansion of abdominal aortic aneurysms

Role of shear stress and stretch in vascular mechanobiology

Segmental differences in the orientation of smooth muscle cells in the tunica media of porcine aortae

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