Changes in the microstructure of the human aortic adventitia under biaxial loading investigated by multi-photon microscopy

Pukaluk, Anna; Wolinski, Heimo; Viertler, Christian; Regitnig, Peter; Holzapfel, Gerhard; Sommer, Gerhard

doi:10.1016/j.actbio.2023.02.027

Cited by 10 publications

(5 citation statements)

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“…Obtaining results similar to those of this study, Pukaluk et al [26,32] recently published two articles in which they analyzed the microstructural changes of the human aortic medial layer and adventitia under biaxial loading and recorded an average stretch ratio at failure of 1.31 (between 1.2 and 1.4), a Cauchy stress between 200-600 kPa for the adventitia, and at an average stretch ratio at failure of 1.35 (between 1.26 and 1.4), a maximum Cauchy stress below 400 kPa for the medial layer. These results highlight the adventitia's biomechanical role as the aortic wall's last structure of mechanical strength relevance.…”

Section: Discussionsupporting

confidence: 90%

“…Given the involvement of enzymolysis in AAA, the selective proteolytic digestion of the main proteins in the arterial wall matrix (elastin, collagen) has been employed to investigate their fate in aneurysmal degeneration [15][16][17][18][19][20][21][22][23][24][25][26]. Although a number of proteinases may be present and/or involved in these degenerative processes, such studies have mostly used elastase and collagenase.…”

Section: Introductionmentioning

confidence: 99%

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Effect of Ultraviolet Radiation on the Enzymolytic and Biomechanical Profiles of Abdominal Aortic Adventitia Tissue

Arbănaşi,

Russu,

Arbănaşi

et al. 2024

JCM

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Background: The abdominal aortic aneurysm (AAA) is defined as an increase in aortic diameter by more than 50% and is associated with a high risk of rupture and mortality without treatment. The aim of this study is to analyze the role of aortic adventitial collagen photocrosslinking by UV-A irradiation on the biomechanical profile of the aortic wall. Methods: This experimental study is structured in two parts: the first part includes in vitro uniaxial biomechanical evaluation of porcine adventitial tissue subjected to either short-term elastolysis or long-term collagenolysis in an attempt to duplicate two extreme situations as putative stages of aneurysmal degeneration. In the second part, we included biaxial biomechanical evaluation of in vitro human abdominal aortic adventitia and human AAA adventitia specimens. Biomechanical profiles were examined for porcine and human aortic tissue before and after irradiation with UV-A light (365 nm wavelength). Results: On the porcine aortic sample, the enhancing effect of irradiation was evident both on the tissue subjected to elastolysis, which had a high collagen-to-elastin ratio, and on the tissue subjected to prolonged collagenolysis despite being considerably depleted in collagen. Further, the effect of irradiation was conclusively demonstrated in the human adventitia samples, where significant post-irradiation increases in Cauchy stress (longitudinal axis: p = 0.001, circumferential axis: p = 0.004) and Young’s modulus (longitudinal axis: p = 0.03, circumferential axis: p = 0.004) were recorded. Moreover, we have a stronger increase in the strengthening of the AAA adventitia samples following the exposure to UV-A irradiation (p = 0.007) and a statistically significant but not very important increase (p = 0.021) regarding the stiffness in the circumferential axis. Conclusions: The favorable effect of UV irradiation on the strength and stiffness of degraded aortic adventitia in experimental situations mimicking early and later stages of aneurysmal degeneration is essential for the development and potential success of procedures to prevent aneurysmal ruptures. The experiments on human normal and aneurysmal adventitial tissue confirmed the validity and potential success of a procedure based on exposure to UV-A radiation.

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Section: Discussionsupporting

confidence: 90%

Section: Introductionmentioning

confidence: 99%

Effect of Ultraviolet Radiation on the Enzymolytic and Biomechanical Profiles of Abdominal Aortic Adventitia Tissue

Arbănaşi,

Russu,

Arbănaşi

et al. 2024

JCM

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“…The dynamic stress–strain curves were affected by relaxation phenomena during the imaging time (Pukaluk et al. 2023 ). Nevertheless, the dynamic imaging under certain regions of strain experiments show that the 3D orientation index of collagen fibers increased continuously with increasing strain, and that the maximal 3DOI of the elastin fibers was reached before that of the collagen fibers.…”

Section: Discussionmentioning

confidence: 99%

Uniaxial mechanical stretch properties correlated with three-dimensional microstructure of human dermal skin

Zhou,

González,

Van Haasterecht

et al. 2024

Biomech Model Mechanobiol

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The intact and healthy skin forms a barrier to the outside world and protects the body from mechanical impact. The skin is a complex structure with unique mechano-elastic properties. To better direct the design of biomimetic materials and induce skin regeneration in wounds with optimal outcome, more insight is required in how the mechano-elastic properties emerge from the skin’s main constituents, collagen and elastin fibers. Here, we employed two-photon excited autofluorescence and second harmonic generation microscopy to characterize collagen and elastin fibers in 3D in 24 human dermis skin samples. Through uniaxial stretching experiments, we derive uni-directional mechanical properties from resultant stress-strain curves, including the initial Young’s modulus, elastic Young’s modulus, maximal stress, and maximal and mid-strain values. The stress-strain curves show a large variation, with an average Young’s modules in the toe and linear regions of 0.1 MPa and 21 MPa. We performed a comprehensive analysis of the correlation between the key mechanical properties with age and with microstructural parameters, e.g., fiber density, thickness, and orientation. Age was found to correlate negatively with Young’s modulus and collagen density. Moreover, real-time monitoring during uniaxial stretching allowed us to observe changes in collagen and elastin alignment. Elastin fibers aligned significantly in both the heel and linear regions, and the collagen bundles engaged and oriented mainly in the linear region. This research advances our understanding of skin biomechanics and yields input for future first principles full modeling of skin tissue.

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“…Studies investigating the relationship between the arterial microstructure and its mechanical response showed that the arterial wall exhibits a nonlinear and anisotropic behavior under loading with the elastic bers being the primary source of elasticity, and collagen ber waviness and gradual recruitment contributing to nonlinearity (52)(53)(54)(55). Previous studies have further investigated the layer-speci c microstructure and its correlation to arterial mechanical properties (31,56,57). These studies showed sequential engagement of elastic and collagen bers under biaxial loading.…”

Section: Discussionmentioning

confidence: 99%

Renal denervation restores biomechanics of carotid arteries in a rat model of hypertension

Gkousioudi,

Razzoli,

Moreira

et al. 2023

Preprint

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The prevalence of hypertension increases with aging and is associated with increased arterial stiffness. Resistant hypertension is presented when drug treatments fail to regulate a sustained increased blood pressure. Given that the mechanisms between the sympathetic nervous system and the kidney play an important role in blood regulation, renal denervation (RDN) has emerged as a therapeutic potential in resistant hypertension. In this study, we investigated the effects of RDN on the biomechanical response and microstructure of elastic arteries. Common carotid arteries (CCA) were excised from 3-, 8- and 8-month-old denervated rats, and subjected to biaxial extension-inflation test. Our results showed that hypertension developed in the 8-month-old rats. The sustained elevated blood pressure resulted in arterial remodeling which was manifested as a significant stress increase in both axial and circumferential directions after 8 months. RDN had a favorable impact on CCAs with a restoration of stresses in values similar to control arteries at 3 months. After biomechanical testing, arteries were imaged under a multi-photon microscope to identify microstructural changes in extracellular matrix (ECM). Quantification of multi-photon images showed no significant alterations of the main ECM components, elastic and collagen fibers, indicating that arteries remained intact after RDN. Regardless of the experimental group, our microstructural analysis of the multi-photon images revealed that reorientation of the collagen fibers might be the main microstructural mechanism taking place during pressurization with their straightening happening during axial stretching.

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Changes in the microstructure of the human aortic adventitia under biaxial loading investigated by multi-photon microscopy

Cited by 10 publications

References 60 publications

Effect of Ultraviolet Radiation on the Enzymolytic and Biomechanical Profiles of Abdominal Aortic Adventitia Tissue

Effect of Ultraviolet Radiation on the Enzymolytic and Biomechanical Profiles of Abdominal Aortic Adventitia Tissue

Uniaxial mechanical stretch properties correlated with three-dimensional microstructure of human dermal skin

Renal denervation restores biomechanics of carotid arteries in a rat model of hypertension

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