Biomedical Engineering Reference
In-Depth Information
Cellular biodegradation of calcium orthophosphate bioceramics
is known to depend on its phases. For example, a higher solubility of
β-TCP was shown to prevent L-929 fibroblast cell adhesion, thereby
leading to damage and rupture of the cells [646]. A mouse ectopic
model study indicated the maximal bone growth for the 80 : 20 β-TCP
: HA biphasic formulations preloaded with human mesenchymal
stem cells when compared to other calcium orthophosphates
[647]. The effects of substrate microstructure and crystallinity have
been corroborated with an
rabbit femur model, where rod-
like crystalline β-TCP was reported to enhance osteogenesis when
compared to non-rod like crystalline β-TCP [634]. Additionally, using
a dog mandibular defect model, a higher bone formation on a scaffold
surface coated by nanodimensional HA was observed when compared
to that coated by a micro-dimensional HA [648]. Furthermore, recent
studies revealed a stronger stress signaling response by osteoblast
precursor cells in 3D scaffolds when compared to 2D surfaces [649].
Besides, variations in the physical properties of a bone substitute
material (in that case, β-TCP was studied) were found to influence
the inflammatory reaction and its consequences [650].
Mesenchymal stem cells are one of the most attractive cellular
lines for application as bone grafts [651]. Early investigations
by Okumura et al. indicated an adhesion, proliferation and
differentiation, which ultimately became new bone and integrated
with porous HA bioceramics [652]. Recently, Unger et al. showed
a sustained co-culture of endothelial cells and osteoblasts on
HA scaffolds for up to 6 weeks [653]. Furthermore, a release of
factors by endothelial and osteoblast cells in co-culture supported
proliferation and differentiation was suggested to ultimately result
in microcapillary-like vessel formation and supported a neo-tissue
growth within the scaffold [408]. More to the point, investigation
of rat calvaria osteoblasts cultured on transparent HA bioceramics,
as well as the analysis of osteogenic-induced human bone marrow
stromal cells at different time points of culturing indicated to a good
cytocompatibility of HA bioceramics and revealed favorable cell
proliferation [368]. Positive results for other types of cells have been
obtained in other studies [206, 363, 364, 367].
Interestingly, but HA scaffolds with marrow stromal cells in a
perfused environment were reported to result in ~85% increase
in mean core strength, a ~130% increase in failure energy and a
~355% increase in post-failure strength. The increase in mineral
in vivo
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