Advances in Collagen-based Tissue Engineering - Natural Polymers, Biopolymers, Biomaterials, and Their Composites, Blends, and IPNs - page 206

to use it in medical application. One major advantage of collagen from aquatic organ-
ism sources in comparison to land animals is that they are not associated with the risk
of outbreak of bovine spongiform encephalopathy. Unfortunately, the great differences
exist between fish collagen and bovine collagen. The relatively fast biodegradation
rate and low thermo-stability of fish collagen in comparison to bovine collagen has
been one of the crucial factors that limit the usage of fish collagen in tissue engineer-
ing. There have been few reports on the modification of fish collagen by chemical and
physical methods (Nalinanon et al. 2011; Pietrucha and Banas, 2010; Yunoki et al.,
2007). The attention has been particularly paid to the cross-linking efficiency, hydro-
thermal stability and porosity of the new class of matrix.
Glycosaminoglycans
In creation of functional scaffolds for tissue engineering the role of both collagen
and GAG such as HA and CS are important (O'Brien et al., 2005; Pieper et al., 2000;
Zhong et al., 2007) HA and CS belong to the connective-tissue mucopolysaccharide
group of substances that are present mainly in articular cartilage, vitreous humour and
synovial fluid but they are widely distributed in other tissues and most body liquids.
They have unique physicochemical properties and distinctive biological functions.
Composites collagen-GAG has been used for a wide variety of in vitro studies of cel-
lular migration, contraction, and tissue growth.
Other Components for Scaffolds
Cellulose is a linear homopolymer of glucose and is the most widespread polymeric
material in nature. It is degradable by enzymes and its solubility in water depends on
its chain length. The biocompatibility of cellulose and good match of their mechani-
cal properties with those of hard and soft tissue accounts for its medical applications
(Czaja et al., 2007; Fatimi et al., 2008). It has been used in research in both bone
and cartilage tissue engineering. Cellulose derivatives such as carboxymethylcellu-
lose (CMC), hydroxypropylmethylcellulose (HPMC) and oxidized cellulose are also
known to have good biocompatibility. The biocompatibility of methylcellulose (MC)
in the peritoneum is not known, but the mixture of MC and HA has been reported to
be biocompatible in intrathecal injection. Many work has been done on application of
poly(lactic acid) (PLA) and poly(lactic-co-glycolic acid) (PLGA) in medical applica-
tion (Kuo and Yeh, 2011).
To summarize, the materials for tissue engineering are based on optimized com-
position of several types of natural/synthetic, biocompatible, and biodegradable com-
ponents:
• Collagen: low mechanical strength, relative rapid biodegradation, good cell ad-
hesion, migration, and proliferation;
• Cellulose, or a cellulose derivative: good mechanical strength, slow degrada-
tion, poor cell adhesion;
• Glycosaminoglycans: The HA and CS: special function in assisting cell migra-
tion and cell differentiation during the healing process. Through its high water
absorption, resists forces of compression, while collagen and cellulose with-
stand tensile forces;