Biomedical Engineering Reference
In-Depth Information
d
n
3
r
4
n
g
|
1
Figure 9.4
(a) Homogeneous PCL-TCP scaffold. (b) Functionally graded PCL-TCP
scaffold. Note the different amounts of TCP in each layer.
34
osteoblast-like cells (MG63). It was found that a 30% increase in water
absorption was induced by functional grading, although the mechanical
properties of this design were lower than that of the homogeneous control;
this was thought to be caused by non-uniform stress distribution. Further-
more, an increase in cell attachment, proliferation and calcium deposition
were recorded in the functionally graded groups after 14 days. However, cell
viability in the functionally graded groups was lower than in the control
groups.
34
Functional grading is a promising and cutting edge technique sure
to be the focus of further research.
Zhou et al.
35
undertook a study comparing the osteogenic potential of
FDM fabricated PCL with PCL-TCP (80 : 20 wt%) scaffolds (RA: 0/60/1201).
The study confirmed that PCL-TCP scaffolds had improved hydrophilicity
and mechanical properties over the control group.
35
Similarly, in vitro
studies conducted using human alveolar osteoblasts also indicated that cells
on PCL-TCP scaffolds demonstrate better proliferation, formation of denser
multilayered cell sheets and earlier expression of bone matrix-related pro-
teins than on PCL-only scaffolds.
35
It was found, however, that the bone
specific proteins were mostly found at the border region of the constructs,
with only a few in the interior. This uneven distribution of the matrix pro-
teins was attributed to the potentially limited supply of nutrients available in
static culture, as well as the formation of mineralised tissue initially occur-
ring on the outer surface of the constructs, thereby possibly hindering the
exchange of nutrients and waste to the interior part of the scaffolds. Authors
suggested that the uneven tissue formation may be prevented by the use
of a perfusion system which could assist the exchange of nutrients or via
incorporation of osteoinductive factors into the central part of the scaffolds
to promote tissue mineralisation.
35
The same research group next combined FDM engineered PCL-TCP
scaffolds with cell sheets (cells that had been grown to confluency and de-
tached as a single sheet containing cells and extracellular matrix).
36
Studies
in vitro revealed cells within the constructs had undergone osteogenic
differentiation as indicated by elevated alkaline phosphatase levels and
.
Search WWH ::
Custom Search