DESIGNING NANOFIBROUS SCAFFOLDS FOR TISSUE ENGINEERING - Advanced Biomaterials: Fundamentals, Processing, and Applications - page 433

natural polymers for more details)[14]. In order for the cells to experience a
native environment, the synthetic scaffold must comply with specifi c require-
ments in terms of physical (including 3D architecture), chemical, mechanical and
surface properties. Some of the desirable characteristics of a scaffold include
[15,16] :
1. The material used to synthesize scaffolds should be biodegradable and the
rate of degradation should be coupled to rate of tissue regeneration.
2. Both the bulk biomaterial and its degradation products should be non-
toxic (biocompatible) and the degradation products should preferably be
metabolized in the body.
3. The scaffold should have high surface area - to - volume ratio to enable max-
imal cell seeding.
4. The scaffold should be porous so as to permit the migration of cells in all
three dimensions.
5. The pores should be interconnected, with a pore network that enables
appropriate transport of nutrients, metabolites and regulatory molecules
to and from the cells within the matrix.
6. The material must meet the mechanical requirements of the tissue at the
site of implantation.
7. The 3D scaffold should be physically and chemically stable and easy to
sterilize.
8. The scaffold should possess the ability to carry bioactive molecules such
as growth factors and deliver the same at an appropriate rate at the site of
interest.
9. The scaffold should have a physicochemical structure that promotes cell
fate processes such as cell adhesion and migration.
Practically, it would be very diffi cult to meet all the aforementioned criteria
for scaffold design. Therefore, the approach most often followed is to achieve as
many criteria as is essential/detrimental for a specifi c application. The choice of
technique for scaffold fabrication depends on the application, the type of bioma-
terial used for scaffold synthesis, and the environment in which the scaffold would
be implanted.
The behavior of cells seeded on a scaffold is infl uenced by the chemical [17]
as well as the physical properties of a scaffold [18,19,20]. The chemical properties
of the scaffold majorly control the biocompatibility and biodegradability of the
scaffold. Chemical properties and hence biodegradation/biocompatibility can be
modulated by using a combination of synthetic and natural polymers [21]. On the
other hand, the infl uence of physical properties of scaffold on cell behavior has
not been extensively studied. Several studies evaluating the importance of geom-
etry of a scaffold in the regulation of cell fate behavior have been reported
recently [22,23,24]. Cells behave differently when cultured on a 3D scaffold than
on a 2D (two dimensional) substrate. For example, chondrocytes maintain their