Decellularization, Stabilization and Functionalization of Collagenous Tissues Used as Cardiovascular Biomaterials - Biomaterials: Physics and Chemistry - page 162

2.2 Properties of collagenous tissues
Collagen-rich tissues are composed of 75% of collagen, 20% of mucopolysaccharides and
water, although elastin can be found in less than 5% (Cauich-Rodríguez, 2008). All these
tissue components maintain the structural and functional integrity of the composite tissue.
Some mechanical properties of collagenous tissues are shown in table 1.

Tissue Property Value Reference

Bovine perichardium Tensile

strength

10.9
MPa

Lee at el., 1989

Strain at
rupture

33.0 %

Tissue
modulus

58.2
MPa

Canine perichardium Tensile

strength

18.4
MPa

Lee & Boughner, 1981; Wiegner & Bing,
1981

Strain at
rupture

21.4 %

Tissue
modulus

198 MPa

Human perichardium Tensile

strength

2.51
MPa

Lee & Boughner, 1985

Strain at
rupture

34.9 %

Tissue
modulus

20.4
MPa

Porcine aortic valve
leaflet

Tensile
strength

6.25
MPa

Lee at el., 1984

Strain at
rupture

30.8 %

54.6
MPa
Table 1. Mechanical properties of some collagenous tissue

Tissue
modulus

The thermal transitions experienced by materials with amorphous and/or crystalline
regions are also observed in the collagenous tissue. When the biomaterial is heated, its
specific volume increases, exhibiting the glass transition of amorphous regions and the
fusion of crystalline collagen fibers to a temperature higher than the glass transition
temperature (Li, 2007). The melting temperature of collagen fibers is an irreversible process
and is often referred in the literature as the denaturation temperature (T d ) or shrinkage
temperature (T s ). In fact, the denaturation temperature is widely used as an indicator of the
tissue stabilization.
The collagenous tissues require chemical or physical treatments in order to be preserved or
stabilized. In fact, the introduction of cardiovascular bioprostheses in 1960s was linked to
the chemical fixation of porcine aortic valves or bovine perichardial tissue with
glutaraldehyde. This process produces a non-living material without the capability of
intrinsic repair as native tissue does after some structural injury (Flanagan & Pandit, 2003).
The processed tissue tends to fail in modes related to the remnant immunogenicity,