Biomedical Engineering Reference
In-Depth Information
based on the premise that the large numbers of platelets found in
PRP release significant quantities of mitogenic polypeptides, such
as platelet-derived growth factors (PDGF), transforming growth
factor-
β
(TGF-
β
), and insulin-like growth factor-I (IGF-I). The
potential effects of PDGF include the stimulation of mitogenesis
of marrow stem cells and the stimulation of angiogenesis.
22
TGF-
β
has been shown to stimulate chemotaxis and mitogenesis of
osteoblast precursors, stimulate the deposition of a collagen matrix
for connective tissue healing and bone formation, and inhibit
osteoclast formation and boneresorption.
23
Before clinical application, we investigated the ability of bone
regeneration by using the dog mandible model. The implanted
regions were collected at two, four, and eight weeks and processed
and decalcified for histology. The result showed that the cortical
continuity was never restored and the cavities were invaded
by a fibrous tissue and less new bone formation was seen
in the PRP group (scaffold only). On the other hand, cavi-
ties filled with the TEB resulted in new bone formation even
after two weeks, with a tubular pattern at eight weeks and
abundant vascularization. This pattern reflected a normal bone
macrostructure with a well-differentiated marrow cavity compared
with cavities filled with autogenous particulate cancellous bone
and marrow (PCBM), which showed space by PCBM resorption
(Fig. 40.6).
18
So the TEB-implanted group vascularized well. Ideally, the
scaffold should be resorbed at a rate commensurate with new
bone formation, within a few weeks. This makes it very different
from most hydroxyapatite,
-TCP ceramics,
8
or coral scaffolds
24
that virtually do not degrade during the first few weeks of
implantation. Presumably, the disappearance of the TEB left in
place induced bone tissue formation, which then self-organized
according to the surrounding environment. And the TEB per-
formed better, suggesting a positive influence of PRP for the
MSCs.
After the confirmation based on this series of experimental
studies,itwasperformedonahumanwiththeTEBforalveolarbone
augmentation and simultaneousimplant installation.
19
,
20
,
25
β
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