Biomedical Engineering Reference
In-Depth Information
seeded them with porcine chondrocytes and then implanted them in the
dorsal subcutaneous site of SCID mice and demonstrated the formation
of cartilage-like structures 4 weeks after implantation. Chalain et al. [92]
reported on a reconstruction of elastic cartilages using isolated chondro-
cytes harvested from human and porcine ears. Authors established an in
vitro aggregation of isolated chondrocytes followed by the embedding of
these aggregates in hydrogel synthesized by combination of alginate, col-
lagen type I and k-elastin, and claimed the most effi cient reconstruction
of elastic cartilage after transplantation in athymic mice. Results of in vivo
studies indicated that after four weeks of implantation the chondrocytes
had produced ECM proteins consistent with cartilage [89-92].
1.4.4 Starch-basedMaterials
Starch is the major polysaccharide constituent of plant tissues. It is com-
prised of a mixture of a linear poly(1,4- a -D-glucopyranose) (amylose)
and a branched poly(1,4- a -D-glucopyranose) with branches of (1,6- a -D-
glucopyranose) (amylopectin) occurring nearly every 25 glucosidic moi-
eties [93]. Starch is produced in the form of semicrystalline granules with
different size and composition depending upon the source [93]. This poly-
mer can easily be processed using a variety of techniques to give shape
as required, for example, by 3D porous scaffolds, microparticles and gels.
The starch-based products are totally biodegradable and cost-effective,
and thus facilitate an enormous potential for a wide range of applications
in the biomedical fi eld [94, 95].
Starch-based polymeric systems are commonly blended with other
polymers to provide good mechanical properties. Blends of starch with
ethylene vinyl alcohol (SEVA-C), cellulose acetate (SCA), polycaprolac-
tone (SPCL) and poly(lactic acid) (SPLA) have been proposed as poten-
tial alternative biodegradable materials for a wide range of biomedical
applications [96]. The structure and functional properties of starch-based
blended materials depend on blend components, material processing
technique, incorporation and nature of additives, and reinforcement fi ll-
ers [97-102].
Starch and polycaprolactone blend (SPCL) scaffolds had been fabricated
by melt spinning, followed by fi ber bonding. The processing technique
involves fi ber packing in an appropriate mold with posterior heating below
the melting temperature (T m ) for a determined residence period that will
allow the fi bers to form a stable mesh structure. The material used was a
30/70 (wt.%) blend of corn starch with polycaprolactone (SPCL). These
scaffolds were tested for cartilage tissue engineering. After 6 weeks of
cell culture, bovine articular chondrocytes, seeded on the scaffolds under
dynamic conditions, presented normal morphological features with an
extensive presence of cells at the surface of the support structures, and
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