Biomedical Engineering Reference
In-Depth Information
several questions regarding donor site, isolation and expansion methods, and
stem cell behaviour. Moreover, such demanding protocols are less likely to be
reproducible in tumoral surgery owing to waiting times and high costs. The ex-
perimental results indicated successful bone ingrowth of the composite associat-
ing MBCP® + collagen membrane+ post radiation total BM graft in a critical size
defect in rabbit femurs. Bridging of the defect with lamellar and well-organised
bone was achieved in all animals. These observations are consistent with a biome-
chanical stimulated implant due to chosen osteosynthesis. The quantities of bone
and ceramic were identical at the different levels of the implant, which is unusual
in macroporous calcium phosphate bioceramics where centripetal bone colonisa-
tion is classic. These observations suggest that bone marrow grafts in the centre of
a defect may have osteoinductive properties. Although the whole axial plane of
the defect was not completely fi lled with newly-formed bone, a tendency for peri-
osteum-like formation was observed in most animals. The collagen membrane is
a biocompatible barrier that also acts as a resorbable healing scaffold that can
lead to periosteum-like tissue formation on the external bony surface [87].
This study allowed the authors to better defi ne bone tissue engineering
models by determining the most favorable donor site—which is the humeral site
in both dog and rabbit models—and to achieve optimal outcomes in further ir-
radiated bone regeneration studies. These fi ndings show that a composite associ-
ating a collagen membrane fi lled with MBCP® granules with a total autologous
bone marrow graft injection can successfully repair a critical segmental defect in
irradiated bone. This has signifi cant implications for the bone tissue engineering
approach to patients with cancer-related segmental bone defects.
Tissue engineering for bone regeneration involves the seeding of osteogenic
cells (that is, mesynchymal stem cells, MSC) on to appropriate scaffolds and sub-
sequent implantation of the seeded scaffolds into the bone defect. Bone marrow-
derived mesenchymal stem cells (MSCs) are multipotential cells that are capable
of differentiating into, at the very least, osteoblasts, chondrocytes, adipocytes,
tenocytes, and myoblasts [88-90]. From a small volume of bone marrow, MSCs
can be isolated and culture-expanded into large numbers due to their prolifera-
tive capacity, and they maintain their functionality after culture expansion and
cryopreservation [91]. MSCs are thus thought to be a readily available and abun-
dant source of cells for tissue engineering applications. Several reports have
shown the effi ciency of BCP scaffolds of different HA/
β
- TCP ratios [92,93] .
4.4.6 BCP Scaffolds with Mesenchymal Stem Cells (MSC)
Arinzeh et al. [93] reported a comparative study of BCP with different HA/
β
-TCP ratios as scaffolds for human mesenchymal stem cells (hMSC) used to in-
duce bone formation. The study was designed to determine the optimum HA/
β
-TCP ratio in BCP in combination with MSCs that would promote rapid and
uniform bone formation
in
vivo
. Their study demonstrated that the BCP scaffold
with the lower HA/
-TCP ratio (20/80) loaded with hMSCs promoted the great-
est amount of bone and the new bone formed was uniformly distributed through-
β
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