Collagen fibrils are the main structural component of load-bearing tissues such as tendons, ligaments, skin, the cornea of the eye, and the heart. The D-band of collagen fibrils is an axial periodic density modulation that can be easily characterized by tissue-level X-ray scattering. During mechanical testing, D-band strain is often used as a proxy for fibril strain. However, this approach ignores the coupling between strain and molecular tilt. We examine the validity of this approximation using an elastomeric collagen fibril model that includes both the D-band and a molecular tilt field. In the low strain regime, we show that the D-band strain substantially underestimates fibril strain for strongly twisted collagen fibrils - such as fibrils from skin or corneal tissue.
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http://dx.doi.org/10.1016/j.jmbbm.2021.104854 | DOI Listing |
Acta Biomater
January 2025
Department of Materials Science and Engineering, Stanford University, Stanford, CA, USA. Electronic address:
Hydrogels composed of collagen, the most abundant protein in the human body, are widely used as scaffolds for tissue engineering due to their ability to support cellular activity. However, collagen hydrogels with encapsulated cells often experience bulk contraction due to cell-generated forces, and conventional strategies to mitigate this undesired deformation often compromise either the fibrillar microstructure or cytocompatibility of the collagen. To support the spreading of encapsulated cells while preserving the structural integrity of the gels, we present an interpenetrating network (IPN) of two distinct collagen networks with different crosslinking mechanisms and microstructures.
View Article and Find Full Text PDFJ Biomed Mater Res B Appl Biomater
January 2025
The Laboratory of Orthopaedic Tissue Regeneration & Orthobiologics, Department of Bioengineering, Clemson University, Clemson, South Carolina, USA.
The formation of fibrocartilage in microfracture (MFX) severely limits its long-term outlook. There is consensus in the scientific community that the placement of an appropriate scaffold in the MFX defect site can promote hyaline cartilage formation and improve therapeutic benefit. Accordingly, in this work, a novel natural biomaterial-the cartilage analog (CA)-which met criteria favorable for chondrogenesis, was evaluated in vitro to determine its candidacy as a potential MFX scaffold.
View Article and Find Full Text PDFInt J Mol Sci
December 2024
Department of Vascular Surgery, RWTH Aachen University Hospital, 52074 Aachen, Germany.
Thoracoabdominal aortic aneurysms (TAAAs) are rare but serious conditions characterized by dilation of the aorta characterized by remodeling of the vessel wall, with changes in the elastin and collagen content. Individuals with Marfan syndrome have a genetic predisposition for elastic fiber fragmentation and elastin degradation and are prone to early aneurysm formation and progression. Our objective was to analyze the medial collagen characteristics through histological, polarized light microscopy, and electron microscopy methods across the thoracic and abdominal aorta in twenty-five patients undergoing open surgical repair, including nine with Marfan syndrome.
View Article and Find Full Text PDFActa Biomater
January 2025
Department of Biomedical Engineering, University of Connecticut, Storrs, CT, United States; School of Mechanical, Aerospace, and Manufacturing Engineering, University of Connecticut, Storrs, CT, United States. Electronic address:
In this study we investigate the mechanics of type II collagen fibrils, an essential structural component in many load-bearing tissues including cartilage. Although type II collagen plays a crucial role in maintaining tissue integrity, the stress-stretch and failure response of type II collagen fibrils in tension is not established in the current mechanics literature. To address this knowledge gap, we conducted tensile tests on isolated collagen networks from articular cartilage and established a validated constitutive model for type II collagen fibril.
View Article and Find Full Text PDFLaryngoscope Investig Otolaryngol
February 2025
Objectives: This study aimed to investigate the histological and ultrastructural features of the elastic cartilage at the tip of the vocal process in the arytenoid cartilage, which is essential for laryngeal biomechanics.
Methods: Five larynges, including the vocal folds and epiglottis, were examined using transmission electron microscopy. The elastic cartilage at the tip of the vocal process was compared to the epiglottic cartilage within the same larynx to elucidate structural differences.
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