Biomedical Engineering Reference
In-Depth Information
the cells of choice next only to autologous primary cells [217] that have been
used to engineer mesenchymal tissues such as bone and cartilage. Under appro-
priate culture conditions, MSCs can be caused to differentiate into more
mature cell types of mesenchymal origin such as osteoblasts, chondrocytes and
myoblasts. Petite et al. demonstrated that MSCs seeded on coral scaffolds led
to complete bone reconstitution in large bone defects of a sheep model [218].
Bone marrow fi broblasts of human and mouse origin have been demonstrated
as potential sources in bone regeneration [219]. The usage of progenitor cells
from other lineages, including mesodermal origin, has also been explored for
bone tissue engineering applications [220-222]. Other sources like subcutaneous
adipose tissue have been explored as additional sources for bone-tissue engineer-
ing [223,224]. In addition to these, pulp tissue of human teeth has also been
exploited for the generation of MSCs for potential use in bone-tissue engineering
[225] .
13.5.2.1.2 SCAFFOLDS FOR BONE TISSUE ENGINEERING. The scaffold for bone
tissue engineering should possess critical properties like porosity (pore size
ranging from 200 - 900
m), appropriate mechanical properties, and surface prop-
erties that facilitate cell adhesion and proliferation [215]. Since the ECM of bone
is mostly composed of type I collagen fi brous network with hydroxyapatite (HA)
well distributed in it, the mimic of ECM must resemble the properties of type I
collagen and HA in combination. The approach of mimicking the ECM through
scaffold designing has led the researchers to explore nanofi brous scaffolds
synthesized using the electrospinning technique. Materials that mimic both the
organic and the inorganic components of bone tissues have been electrospun.
The inorganic component HA together with its fl uoridates, fl uor - hydroxyapatite
(FHA), have shown potential as biomaterial for dental applications. Apart from
possessing requisite mechanical strength, HA and FHA also stimulate positive
osteoblast response. Kim et al. [226] demonstrated electrospinning of HA and
FHA and synthesized nanofi bers ranging from hundreds of nanometers to several
micrometers (236 nm - 1.55
μ
m) by modulating processing parameters (mainly the
concentration of polymer solution). Further, FHA nanofi bers demonstrated effi -
cient fl uorine release profi le, thereby making them potential candidates for dental
applications.
Natural polymers like silk have also been explored for bone tissue engineer-
ing primarily due to its inherent biocompatibility, slow-degradability and high
mechanical properties. In a recent study, Li et al. demonstrated the synthesis of
silk - PEO nanofi bers using the electrospinning technique [102]. Highest calcium
levels with improved bone formation were observed following 31 days of static
culture of human bone marrow derived mesenchymal stem cells (hMSCs) on
silk-PEO scaffolds containing bone morphogenetic protein-2 (BMP-2) and HA
nanoparticles. The authors underscored the importance of the combination of
nano-scale features offered by electrospun fi bers and functional features pro-
vided by BMP-2 and hydroxyapatite, thereby demonstrating the potential of silk-
PEO nanofi brous scaffolds in bone tissue engineering.
μ
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