Biomedical Engineering Reference
In-Depth Information
A
Blood Vessels
Biodegradable Polymer Scaffold
Implantation
Interconnected Pore Network
Host Tissue
Defect
B
Blood Vessels
Biodegradable Polymer Scaffold
Implantation
Pre-cultured Cells
Host Tissue
Defect
Fig. 7.1.4-1 Applications of bioresorbable polymers as porous scaffolds in tissue engineering. (A) Tissue induction. (B) Cell transplantation.
(C) Prevascularization. (D) In situ polymerization. In all cases, the porous scaffolds allow tissue ingrowth as they degrade gradually.
encapsulated within microparticles that are degraded
through enzymatic actions, such as gelatin (
Holland
et al.
,
2003
), the concentration and activity of these enzymes
may also affect the release profile of the factors from
composite scaffolds.
organic solvents; and/or (3) incorporating and leaching of
porogens (gelatin microspheres, salt crystals, etc.) in water
(
Temenoff and Mikos, 2000
).
These processes usually result in decrease in molecular
weight and have profound effects on the biocompatibility,
mechanical properties, and other characteristics of the
formed scaffold. Incorporation of large bioactive mole-
cules such as proteins into the scaffolds and retention of
their activity have been a major challenge.
Scaffold processing techniques
The technique used to manufacture synthetic bioresorb-
able polymers into suitable scaffolds for tissue regeneration
depends on the properties of the polymer and its intended
application (
Table 7.1.4-3
). Scaffold processing usually
involves (1) heating the polymers above their glass transi-
tion or melting temperatures; (2) dissolving them in
Fiber bonding
Fibers provide a large surface-area-to-volume ratio and
are therefore desirable as scaffold materials. PGA fibers
in the form of tassels and felts have been utilized as
