Lamellar orientation in human cornea in relation to mechanical properties

Boote, Craig; Dennis, Sally; Huang, Yifei; Quantock, Andrew J.; Meek, Keith Michael Andrew

doi:10.1016/j.jsb.2004.08.009

Cited by 156 publications

(160 citation statements)

References 17 publications

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“…Tendons exhibit viscoelastic and plastic properties, both essential in transmitting muscle-contraction-induced tensile strains into movements, whilst maintaining structural integrity [245][246][247]. The collagenous network is considered to be the main load-bearing structure, through intra-and inter-molecular cross-links between the adjacent helical molecules [248][249][250][251][252]. Non-collagenous macromolecules are also important, but to a lesser extent [253,254].…”

Section: Mechanical Properties Of Tendon Tissuementioning

confidence: 99%

The past, present and future in scaffold-based tendon treatments

Lomas

Ryan

Sorushanova

et al. 2015

Advanced Drug Delivery Reviews

177

188

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Section: Mechanical Properties Of Tendon Tissuementioning

confidence: 99%

The past, present and future in scaffold-based tendon treatments

Lomas

Ryan

Sorushanova

et al. 2015

Advanced Drug Delivery Reviews

177

188

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“…The unique transparent quality of the cornea arises from its remarkably ordered architecture of aligned and regularly spaced fibrils with a small, consistent diameter (∼30 nm), which are arranged, not into fibers or fascicles as in most other tissues but in superimposed, flattened layers, or lamellae. Lamellae and their component collagen fibrils exhibit preferential orientations throughout the corneal thickness (3), which appear to be closely related to the biomechanical loads to which the tissue is subjected. In adult vertebrates, lamellae traverse the full diameter of the cornea for most of its thickness, and in the avian eye-the subject of most developmental studies-undergo a gradual rotation in their orientation with depth (4).…”

mentioning

confidence: 99%

Three-dimensional aspects of matrix assembly by cells in the developing cornea

Young

Knupp

Pinali

et al. 2014

Proc. Natl. Acad. Sci. U.S.A.

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Cell-directed deposition of aligned collagen fibrils during corneal embryogenesis is poorly understood, despite the fact that it is the basis for the formation of a corneal stroma that must be transparent to visible light and biomechanically stable. Previous studies of the structural development of the specialized matrix in the cornea have been restricted to examinations of tissue sections by conventional light or electron microscopy. Here, we use volume scanning electron microscopy, with sequential removal of ultrathin surface tissue sections achieved either by ablation with a focused ion beam or by serial block face diamond knife microtomy, to examine the microanatomy of the cornea in three dimensions and in large tissue volumes. The results show that corneal keratocytes occupy a significantly greater tissue volume than was previously thought, and there is a clear orthogonality in cell and matrix organization, quantifiable by Fourier analysis. Three-dimensional reconstructions reveal actin-associated tubular cell protrusions, reminiscent of filopodia, but extending more than 30 μm into the extracellular space. The highly extended network of these membrane-bound structures mirrors the alignment of collagen bundles and emergent lamellae and, we propose, plays a fundamental role in dictating the orientation of collagen in the developing cornea.C onnective tissues fulfill diverse functions but conform to a general structural plan of cells surrounded by an extracellular matrix in which collagen is the main structural element (1, 2). Composition and tissue-specific organization of the component collagen fibrils are considered to be critically important for the functional properties of any particular tissue. The unique transparent quality of the cornea arises from its remarkably ordered architecture of aligned and regularly spaced fibrils with a small, consistent diameter (∼30 nm), which are arranged, not into fibers or fascicles as in most other tissues but in superimposed, flattened layers, or lamellae. Lamellae and their component collagen fibrils exhibit preferential orientations throughout the corneal thickness (3), which appear to be closely related to the biomechanical loads to which the tissue is subjected. In adult vertebrates, lamellae traverse the full diameter of the cornea for most of its thickness, and in the avian eye-the subject of most developmental studies-undergo a gradual rotation in their orientation with depth (4). Individual collagen fibrils within midstromal lamellae also appear to traverse the entire diameter of the cornea, a distance of ∼11 mm in adult human eyes. The extraordinary level of order in matrix organization within a hierarchy of fibril, lamella, and stroma overall appears to reflect a considerable level of regulatory influence presumably involving both cell activity and intermolecular interactions.Collagen fibrils exhibit a microfibrillar substructure (5-7), undergoing self-assembly spontaneously in vitro from soluble monomeric collagen in a process largely dependent upon the phy...

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“…• sector about the NT axis were recruited then the stiffness parameter α could be corrected for the fact that about a third of the total distribution [11] were being loaded. With these assumptions, 6 free parameters {α, β, µ, τ 1 , τ 2 , c} were left.…”

Section: Resultsmentioning

confidence: 99%

“…Each layer of (nearly) parallel fibrils lies obliquely to the neighboring layers, see, e.g., [69, Figure 1]. Within the central cornea, fibrils tend to run from limbus to limbus, and are preferentially aligned along inferior-superior (IS) and nasal-temporal (NT) axes [58,11]. Near the edge of the cornea, fibrils tend to be aligned circumferentially.…”

Section: Introductionmentioning

confidence: 99%

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The mechanics of soft biological composites.

Nguyen

Grazier²,

Boyce³

et al. 2007

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Biological tissues are uniquely structured materials with technologically appealing properties. Soft tissues such as skin, are constructed from a composite of strong fibrils and fluid-like matrix components. This was the first coordinated experimental/modeling project at Sandia or in the open literature to consider the mechanics of micromechanically-based anisotropy and viscoelasticity of soft biological tissues. We have exploited and applied Sandia's expertise in experimentation and mechanics modeling to better elucidate the behavior of collagen fibril-reinforced soft tissues.The purpose of this project was to provide a detailed understanding of the deformation of ocular tissues, specifically the highly structured skin-like tissue in the cornea. This discovery improved our knowledge of soft/complex materials testing and modeling. It also provided insight into the way that cornea tissue is bio-engineered such that under physiologically-relevant conditions it has a unique set of properties which enhance functionality. These results also provide insight into how non-phsyiologic loading conditions, such as corrective surgeries, may push the cornea outside of its natural design window, resulting in unexpected non-linear responses. Furthermore, this project created a clearer understanding of the mechanics of soft tissues that could lead to bio-inspired materials, such as highly supple and impact resistant body armor, and improve our design of human-machine interfaces, such as micro-electricalmechanical (MEMS) based prosthetics. Through this study,

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Lamellar orientation in human cornea in relation to mechanical properties

Cited by 156 publications

References 17 publications

The past, present and future in scaffold-based tendon treatments

The past, present and future in scaffold-based tendon treatments

Three-dimensional aspects of matrix assembly by cells in the developing cornea

The mechanics of soft biological composites.

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