Biomedical Engineering Reference
In-Depth Information
Fig. 10
Cotransplantation of osteoblasts and chondrocytes in RGD-modified alginate en-
abled formation of growth plate-like structures similar to those in developing long bones.
The cellular and tissue morphology at the interface between cartilaginous and bony re-
gions demonstrated cartilage (
a
), transition (
b
), and bone and marrow space (
c
)typical
of the corresponding regions in a growth plate (magnification: 200
×
)(ProcNatlAcadSci
USA [171], with permission of National Academy of Sciences)
pate in bone regeneration (e.g., osteoblasts, bone marrow derived stem cells,
chondrocytes) may also be beneficial (Fig. 10) [57, 59, 171].
4.3
Nerve Regeneration
4.3.1
Therapeutic Significance of VEGF
Severe nerve damage, as a consequence of injuries or degenerative disor-
ders such as Alzheimer's or Parkinson's disease, affects millions of people
in the prime of their life, and is often incurable, disabling, and fatal. VEGF
has recently been recognized to play a fundamental role in nerve regen-
eration by both providing growth and survival signals to neural cells, and
enhancing vascularization. Following nerve damage, VEGF is up-regulated
and activates proliferation, migration, and survival of various nerve cells, in-
cluding neurons and glial cells [27, 172-174]. Concomitantly, VEGF promotes
blood vessel ingrowth and ultimately guides the branching, differentiation,
and overall function of nerves. A synergistic interplay of VEGF and other
growth factors, as well as crosstalk between nerve cells and endothelial cells,
arecriticaltothisend.Nervegrowthfactor(NGF)wasthefirstidentifiedand
best characterized neurotrophic factor. Recent evidence suggests that NGF
elicits an angiogenic response from cells, and that its neurotrophic capacity
may at least partly be linked to this ability [175-177]. Despite the therapeutic
potential of NGF, early attempts to develop clinical treatments with this factor
were not successful [178]. The inability of these approaches to mimic biologic
events, such as combined presentation of VEGF and NGF, may be partially
responsible for the failure of the trials.
