Biomedical Engineering Reference
In-Depth Information
year, Vacanti et al. [776] reported the case of a man who had a
traumatic avulsion of the distal phalanx of a thumb. The phalanx was
replaced with a specially treated natural coral (porous HA; 500-pore
ProOsteon (see Table 4.2)) implant that was previously seeded with
in vitro
expanded autologous periosteal cells. The procedure resulted
in the functional restoration of a stable and biomechanically sound
thumb of normal length, without the pain and complications that are
usually associated with harvesting a bone graft.
Morishita et al. [777] treated a defect resulting from surgery
of benign bone tumors in three patients using HA scaffolds seeded
with
expanded autologous bone marrow stromal cells after
osteogenic differentiation of the cells. Two bone defects in a tibia
and one defect in a femur were treated. Although ectopic implants
in nude mice were mentioned to show the osteogenicity of the cells,
details such as the percentage of the implants containing bone and at
what quantities were not reported. Furthermore, cell-seeded calcium
orthophosphate scaffolds were found to be superior to autograft,
allograft or cell-seeded allograft in terms of bone formation at
ectopic implantation sites [778]. Besides, it has been hypothesized
that dental follicle cells combined with β-TCP bioceramics might
become a novel therapeutic strategy to restore periodontal defects
[779].
in vitro
4.8
Conclusions and Outlook
The available chronology of seeking for a suitable bioceramics for
bone substitutes is as follows: since the 1950s, the first aim was
to use bioinert [592] bioceramics, which had no reaction with
living tissues. They included inert and tolerant compounds, which
were designed to withstand physiological stress without, however,
stimulating any specific cellular responses. Later on, in the 1980s,
the trend changed towards exactly the opposite: the idea was to
implant bioceramics that reacted with the surrounding tissues
by producing newly formed bone (a “responsive” bioceramics
because it was able to elicit biological responses). These two stages
have been referred to as the first and the second generations of
bioceramics, respectively [780] and, currently, both of them are
extensively commercialized. Thus, the majority of the marketable
products listed in Table 4.2 belong to the first and the second
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