Advances in Collagen-based Tissue Engineering - Natural Polymers, Biopolymers, Biomaterials, and Their Composites, Blends, and IPNs - page 205

agents to enhance and direct it ( Jagur-Grodzinski, 2006). There are several approaches
to creating tissue constructs. A well known one is to isolate specific cells through a
small biopsy from the patient, to grow them on a three dimensional (3D) biomimetic
scaffold, under precisely controlled culture conditions and to deliver the construct to
the appropriate site in the patient's body, and to direct new tissue formation into the
scaffold that would itself disappear, in due course, through biodegradation.
strateGy For CoNstruCtioN oF Biomaterials/sCaFFolds
In this way, biomaterials or scaffolds play a pivotal role in tissue engineering (Ma,
2008). They serve matrices for cell migration, spreading, in growth, proliferation, and
stereo formation of new tissue. An ideal artificial scaffold should resemble the struc-
tural and functional profile of the natural ECM (Wen et al., 2005; Williams, 2006).
selection of Polymer for scaffold
The strategy for the tissue engineering is to select a polymer with the best biocompat-
ibility, extend its time-scale of biodegradation, increase its mechanical strength and
convert it into nano-fiber structure resembling the structure and properties of natural
tissue.
Collagen
Many natural and synthetic polymers have been extensively studied for preparation
of biomaterials/scaffolds for tissue engineering applications but collagen occupies a
unique place in the way it interactions with body tissues. Collagen is an essential
component of ECM in many tissues such as skin, bone, cartilage tendon, and so on.
General reviews of this natural polymer for biomedical applications, with references
to numerous review papers dealing with various specific aspects of this subject have
been published (Kolacna et al., 2007; Wess, 2008). Collagen is the primary structural
material of vertebrates and is the most abundant mammalian protein accounting for ~
30% of total body proteins. Reconstituted collagen from xenogeneic sources due to it
is the excellent biocompatibility and due to its biological characteristic, is regarded as
one of the most useful biomaterials. Collagen has a unique structure and amino acid
sequence. Among the 29 isotypes of collagen, type I is composed of two α 1 chains and
one α 2 chain. The underlying α chains that form these natural polymers are arranged
into repeating motif exhibits a 67 nm interval that forms a coiled structure. The col-
lagen molecule consists of three polypeptide chains twined around one another as in
a three-stranded rope. The specific complement of α subunit present within the fibril
defines the material properties of the polymer. Besides, in native ECM, collagen exists
in a 3D network structure composed of multi-fibrils in the nano-fiber scale of 50-500
nm. The fibrillar structure of Type I collagen has been known for a long time to play
an important part in cell attachment, proliferation, and differentiated function in tissue
culture.
Collagens from different species and living environments have various properties.
An alternative to mammalian collagen is fish collagen. Production of fish collagen is
actually not new it has been produced for many years (Zhang et al., 2009). Nowadays,
the importance of fish collagen is growing and there is growing number of possibilities