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. 2014:2014:189197.
doi: 10.1155/2014/189197. Epub 2014 Sep 14.

Age dependent differences in collagen alignment of glutaraldehyde fixed bovine pericardium

Katie H Sizeland  1 , Hannah C Wells  1 , John Higgins  2 , Crystal M Cunanan  3 , Nigel Kirby  4 , Adrian Hawley  4 , Stephen T Mudie  4 , Richard G Haverkamp  1
Affiliations

Age dependent differences in collagen alignment of glutaraldehyde fixed bovine pericardium

Katie H Sizeland et al. Biomed Res Int. 2014.

Abstract

Bovine pericardium is used for heart valve leaflet replacement where the strength and thinness are critical properties. Pericardium from neonatal animals (4-7 days old) is advantageously thinner and is considered as an alternative to that from adult animals. Here, the structures of adult and neonatal bovine pericardium tissues fixed with glutaraldehyde are characterized by synchrotron-based small angle X-ray scattering (SAXS) and compared with the mechanical properties of these materials. Significant differences are observed between adult and neonatal tissue. The glutaraldehyde fixed neonatal tissue has a higher modulus of elasticity (83.7 MPa) than adult pericardium (33.5 MPa) and a higher normalised ultimate tensile strength (32.9 MPa) than adult pericardium (19.1 MPa). Measured edge on to the tissue, the collagen in neonatal pericardium is significantly more aligned (orientation index (OI) 0.78) than that in adult pericardium (OI 0.62). There is no difference in the fibril diameter between neonatal and adult pericardium. It is shown that high alignment in the plane of the tissue provides the mechanism for the increased strength of the neonatal material. The superior strength of neonatal compared with adult tissue supports the use of neonatal bovine pericardium in heterografts.

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Figures

Figure 1
Figure 1
Flattened pericardium, after cutting, held with weights around the edge.
Figure 2
Figure 2
Directions of X-ray analysis of samples.
Figure 3
Figure 3
Pericardium stained with picrosirius red and imaged through cross-polarized light to highlight collagen: (a) adult pericardium; (b) neonatal pericardium. The parietal side is toward the left and the fibrous side toward the right of each image. Scale bar is 0.1 mm.
Figure 4
Figure 4
SAXS spectra of pericardium. (a) A poorly oriented tissue; (b) a highly oriented tissue.
Figure 5
Figure 5
SAXS profile of an example bovine pericardium integrated around all azimuthal angles. The sharp peaks due to collagen D-spacing of various orders are visible (order 5 is just below 0.05 Å−1, order 6 at just below 0.06 Å−1, etc.).
Figure 6
Figure 6
Plots of the intensity of a selected collagen peak at varying azimuthal angles for bovine pericardium samples. (a) A poorly aligned tissue; (b) a highly aligned tissue. The central peak at 180° (and other peaks at 0 and 360°) is the variation in intensity of collagen D-spacing whereas the lower peaks at 90° and 270° are due to the scattering from the thickness of the fibrils and fibril bundles.
Figure 7
Figure 7
Variation of orientation index through the thickness of glutaraldehyde fixed pericardium: (a) adult; (b) neonatal. Each figure shows two profiles for each of the two samples.
See this image and copyright information in PMC

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