Calcium Orthophosphates as Bioceramics - Calcium Orthophosphates: Applications in Nature, Biology and Medicine - page 390

vitro using patient or donor cells and a bioresorbable scaffold and

then is implanted into the patients to replace diseased or damaged
tissues. For regeneration, a scaffold implanted directly into the

injured tissue stimulates the body's own cells to promote local tissue
repair [657, 759]. In any case, simply trapping cells at the particular
point on a surface is not enough: the cells must be encouraged to
differentiate, which is impossible without the presence of suitable
biochemical factors [760]. All previously mentioned clearly indicates
that for the purposes of tissue engineering, calcium orthophosphate
bioceramics plays an auxiliary role; namely, it acts as a suitable
material to manufacture the appropriate 3D templates, substrates
or scaffolds to be colonized by living cells before the successive
implantation [761, 762]. The

in situ

evaluation of potential calcium
orthophosphate scaffolds for tissue engineering has been described
elsewhere [763], while the data on the mechanical properties of
calcium orthophosphate bioceramics for use in tissue engineering
are also available [764, 765]. The effect of a HA-based biomaterial on
gene expression in osteoblast-like cells was reported as well [766].
To conclude this part, the excellent biocompatibility of calcium
orthophosphate bioceramics, its possible osteoinductivity [177,
459, 504, 608-621] and a high affinity for drugs [767], proteins
and cells make them very functional for the tissue engineering
applications. The feasible production of scaffolds with tailored
structures and properties opens up a spectacular future for calcium
orthophosphates [766-774].

in vitro

4.7.4 A Clinical Experience

During the last decade, several groups have made steps towards
a clinical application of cell-seeded calcium orthophosphate
bioceramics for bone tissue engineering of humans. For example,
Quarto et al. [775] were the first to report a treatment of large (4-7
cm) bone defects of the tibia, ulna and humerus in three patients
from 16 to 41 years old, where the conventional surgical therapies
had failed. The authors implanted a custom-made unresorbable
porous HA scaffolds seeded with expanded autologous

bone marrow stromal cells. In all three patients, radiographs and
computed tomographic scans revealed abundant callus formation
along the implants and good integration at the interfaces with the
host bones by the second month after surgery [775]. In the same

in vitro