The bovine pericardial xenograft: II. Effect of tethering or pressurization during fixation on the tensile viscoelastic properties of bovine pericardium

Lee, Jang-Ming; Corrente, R; Sa, Haberer

doi:10.1002/jbm.820230503

Cited by 19 publications

(1 citation statement)

References 15 publications

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“…Further, six of the 13 fibrils showed linear behaviour. At the tissue level, our findings are also consistent with the findings of Lee et al [65][66][67], who found no change in MTM in cross-linked pericardial tissues as in our study (table 2). It is interesting to note that, when using the native tissue fibre-ensemble model (equation (4.4)) on both the native and cross-linked data (figure 5), one can increase the fibre modulus determined from the native state to match the post-EXL data (figure 11a).…”

Section: Major Findingssupporting

confidence: 93%

A novel fibre-ensemble level constitutive model for exogenous cross-linked collagenous tissues

2016

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Exogenous cross-linking of soft collagenous tissues is a common method for biomaterial development and medical therapies. To enable improved applications through computational methods, physically realistic constitutive models are required. Yet, despite decades of research, development and clinical use, no such model exists. In this study, we develop the first rigorous full structural model (i.e. explicitly incorporating various features of the collagen fibre architecture) for exogenously cross-linked soft tissues. This was made possible, in-part, with the use of native to cross-linked matched experimental datasets and an extension to the collagenous structural constitutive model so that the uncross-linked collagen fibre responses could be mapped to the cross-linked configuration. This allowed us to separate the effects of cross-linking from kinematic changes induced in the cross-linking process, which in turn allowed the non-fibrous tissue matrix component and the interaction effects to be identified. It was determined that the matrix could be modelled as an isotropic material using a modified Yeoh model. The most novel findings of this study were that: (i) the effective collagen fibre modulus was unaffected by cross-linking and (ii) fibre-ensemble interactions played a large role in stress development, often dominating the total tissue response (depending on the stress component and loading path considered). An important utility of the present model is its ability to separate the effects of exogenous cross-linking on the fibres from changes due to the matrix. Applications of this approach include the utilization in the design of novel chemical treatments to produce specific mechanical responses and the study of fatigue damage in bioprosthetic heart valve biomaterials.

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Section: Major Findingssupporting

confidence: 93%

A novel fibre-ensemble level constitutive model for exogenous cross-linked collagenous tissues

2016

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Optic Nerve Tissue Shrinkage During Pathologic Processing After Enucleation for Retinoblastoma

Abramson

Schefler²,

Almeida

et al. 2003

Arch Ophthalmol

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Objectives: To quantify and analyze the differences between the length of the optic nerve as measured by the ophthalmologist in the operating room after enucleation and the length as measured by the pathologist after fixation. Methods: The authors performed a retrospective review of patients who underwent either primary or secondary enucleation for retinoblastoma at the Ophthalmic Oncology Center of the New York-Presbyterian Hospital-Cornell campus between November 1979 and August 2001. Intraoperative notes and pathologic reports were reviewed to determine the length of the resected optic nerve as recorded by both the surgeon and pathologist. Results: Sufficient data for inclusion in the study were available from 100 enucleation specimens belonging to 96 patients. A significant degree of shrinkage of the optic nerve

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Solvent environment modulates effects of glutaraldehyde crosslinking on tissue-derived biomaterials

Gratzer

Lee

1996

J. Biomed. Mater. Res.

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Bioprosthetic materials utilized in the construction of heart valves and vascular grafts possess limited performance and viability in vivo. This is due (in part) to the failure of these materials to mimic the mechanical properties of the host tissue they replace. If bioprosthetic materials could be engineered to meet the mechanical performance required in vivo, the functional lifetime of implants would be increased. In this study, glutaraldehyde/solvent solutions of decreasing dielectric constant (polarity) were utilized to modify the properties of crosslinked collagen in whole bovine pericardial tissue. Solvents included phosphate buffer, methanol, 95% (w/w) ethanol, n-propanol, and n-butanol. Exogenous crosslinking was verified in collagen by thermal denaturation tests and amino acid analyses. Tensile mechanical behavior of collagenous pericardial samples was found to depend upon the dielectric constant (polarity) of the glutaraldehyde/solvent solutions employed; however, treatment in the solvents alone had little, if any, effect. As the dielectric constant of the solvents decreased, three mechanical properties were systematically altered: plastic strain fell from a mean of 8.9 +/- 1.5% (buffer) to 1.6 +/- 0.4% (n-butanol); strain at fracture increased from 32.2 +/- 2.6% (buffer) to 55.6 +/- 4.6% (n-butanol); and percent stress remaining after 1000-s stress relaxation from an 80-g initial load fell from 86.3 +/- 1.1% (buffer) to 76.9 +/- 1.0% (n-butanol). Crosslinking using a glutaraldehyde/n-butanol solution produced materials with tensile mechanical behavior that was very close to that of fresh tissue; however, the flexural properties of the treated tissue were different from those of fresh tissue. This decoupling of the flexural and tensile mechanical behaviors of crosslinked bioprosthetic materials is unique to this form of treatment. The observed phenomena may be the results of conformational changes in collagen facilitated by polar/nonpolar interactions with the solvent that are "locked in" by the action of glutaraldehyde. This technique may aid in the "customized" design of mechanical properties in tissue-derived biomaterials.

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The bovine pericardial xenograft: II. Effect of tethering or pressurization during fixation on the tensile viscoelastic properties of bovine pericardium

Cited by 19 publications

References 15 publications

A novel fibre-ensemble level constitutive model for exogenous cross-linked collagenous tissues

A novel fibre-ensemble level constitutive model for exogenous cross-linked collagenous tissues

Optic Nerve Tissue Shrinkage During Pathologic Processing After Enucleation for Retinoblastoma

Solvent environment modulates effects of glutaraldehyde crosslinking on tissue-derived biomaterials

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