Mechanical behavior and collagen structure of degenerative mitral valve leaflets and a finite element model of primary mitral regurgitation

Sadeghinia, Mohammad; Aguilera, Hans Martin; Holzapfel, Gerhard; Urheim, Stig; Persson, Robert Matongo; Ellensen, Vegard Skalstad; Haaverstad, Rune; Skallerud, Bjørn; Prot, Victorien

doi:10.1016/j.actbio.2023.03.029

Cited by 12 publications

(11 citation statements)

References 41 publications

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“…Following this, the representative distribution is modeled using a mixture of two von Mises distribution, which is defined as Sadeghinia et al. ( 2023 ): where b is a constant, is the weight factor, and a are the mean fiber angle and concentration parameter, respectively, and the subscript indicates the first or second fiber family and is first kind modified Bessel function of zero order.…”

Section: Methodsmentioning

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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Section: Methodsmentioning

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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“…Specifically, the samples were incubated for 4h each in a , , w/v solution, then for 12h each in a , w/v solution and finally for 24h in a w/w solution (SeeDB solution). All steps took place at C. This technique allows biological tissues to be cleared without significant morphological changes, even in the case of fibrous tissue 64 . After completing the clearing process, the samples were placed in a press-to-seal silicone isolator (CoverWell™ Imaging Chambers, Grace BIO-Labs, Oregon, USA) filled with SeeDBp solution and sealed with two rectangular glass coverslips at the top and bottom.…”

Section: Methodsmentioning

confidence: 99%

Fourier transform-based method for quantifying the three-dimensional orientation distribution of fibrous units

Alberini,

Spagnoli,

Sadeghinia

et al. 2024

Sci Rep

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Several materials and tissues are characterized by a microstructure composed of fibrous units embedded in a ground matrix. In this paper, a novel three-dimensional (3D) Fourier transform-based method for quantifying the distribution of fiber orientations is presented. The method allows for an accurate identification of individual fiber families, their in-plane and out-of-plane dispersion, and showed fast computation times. We validated the method using artificially generated 3D images, in terms of fiber dispersion by considering the error between the standard deviation of the reconstructed and the prescribed distributions of the artificial fibers. In addition, we considered the measured mean orientation angles of the fibers and validated the robustness using a measure of fiber density. Finally, the method is employed to reconstruct a full 3D view of the distribution of collagen fiber orientations based on in vitro second harmonic generation microscopy of collagen fibers in human and mouse skin. The dispersion parameters of the reconstructed fiber network can be used to inform mechanical models of soft fiber-reinforced materials and biological tissues that account for non-symmetrical fiber dispersion.

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“…A customised MATLAB (The MathWorks, Natick, MA, USA) script was developed to assess the dispersion of the collagen fibres in the SHG images, following a previously described method [27]. It employed Fourier transformation and wedge filters to generate a probability density function reflecting the distribution of the collagen fibres.…”

Section: Collagen Anisotropy Analysismentioning

confidence: 99%

“…The relative amplitude of the fibre distribution was determined by this filter. To smooth the data, a moving average filter with a 7 • range was applied to the angle θ [27]. The distribution was fitted by two families of fibres using a von Mises distribution.…”

Section: Collagen Anisotropy Analysismentioning

confidence: 99%

A Comparative Analysis of Orthotopic and Subcutaneous Pancreatic Tumour Models: Tumour Microenvironment and Drug Delivery

Fernandez,

Årbogen,

Sadeghinia

et al. 2023

Cancers

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Pancreatic ductal adenocarcinoma (PDAC) remains a challenging malignancy, mainly due to its resistance to chemotherapy and its complex tumour microenvironment characterised by stromal desmoplasia. There is a need for new strategies to improve the delivery of drugs and therapeutic response. Relevant preclinical tumour models are needed to test potential treatments. This paper compared orthotopic and subcutaneous PDAC tumour models and their suitability for drug delivery studies. A novel aspect was the broad range of tumour properties that were studied, including tumour growth, histopathology, functional vasculature, perfusion, immune cell infiltration, biomechanical characteristics, and especially the extensive analysis of the structure and the orientation of the collagen fibres in the two tumour models. The study unveiled new insights into how these factors impact the uptake of a fluorescent model drug, the macromolecule called 800CW. While the orthotopic model offered a more clinically relevant microenvironment, the subcutaneous model offered advantages for drug delivery studies, primarily due to its reproducibility, and it was characterised by a more efficient drug uptake facilitated by its collagen organisation and well-perfused vasculature. The tumour uptake seemed to be influenced mainly by the structural organisation and the alignment of the collagen fibres and perfusion. Recognising the diverse characteristics of these models and their multifaceted impacts on drug delivery is crucial for designing clinically relevant experiments and improving our understanding of pancreatic cancer biology.

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Mechanical behavior and collagen structure of degenerative mitral valve leaflets and a finite element model of primary mitral regurgitation

Cited by 12 publications

References 41 publications

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

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

Fourier transform-based method for quantifying the three-dimensional orientation distribution of fibrous units

A Comparative Analysis of Orthotopic and Subcutaneous Pancreatic Tumour Models: Tumour Microenvironment and Drug Delivery

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