Biomedical Engineering Reference
In-Depth Information
Stricture of engineered tissue
Porous scaffold
Tubular tissue
Implantation
Engineered tissue
Bioabsorbable stent
Implantation
(Stent resorbed)
Figure 14.6
Protection of a tubular tissue by a biodegradable stent.
benefi cial surface of Scaffold type II for tissue engineering. Moreover, stenting is
very effective in preventing a tubular scaffold from stenosis (narrowing), as dem-
onstrated in Figure 14.6 .
14.4.4
Barrier and Guidance Structure
Any scaffolds for tissue engineering should retain and protect the environment
where the tissue regeneration proceeds. The protection is generally performed by
placing a barrier membrane around the permissive environment for the tissue
regeneration. Well-known examples are the barrier membrane clinically used as
a sheet for the guided tissue regeneration of periodontal tissues and as a tube for
the regeneration of peripheral nerves. A long tube will guide the end of the extend-
ing peripheral nerve to reach the destination. The protection against invading cells
and overloading from the outside will be also achieved by bulky 3D scaffolds to a
certain extent.
In addition, a barrier membrane will act as a container for the bone marrow
harvested from patients. The MSCs present in the bone marrow will initiate tissue
regeneration in the protected environment where the bone marrow has been fi lled.
14.5
Biodegradable Polymers for Tissue Engineering
To fulfi ll the diverse needs in tissue engineering, various biodegradable materials
have been exploited as scaffolds for tissue regeneration. Strictly speaking, biode-
gradable polymers are not identical to bioabsorbable (absorbable or resorbable)
polymers, because the mechanism of polymer disappearance from the implanted
site varies. Biodegradation is defi ned as chain scission of polymers constructing
a biomaterial to shorter chains, fi nally to the monomer or oligomers in biological
