Biomedical Engineering Reference
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inhibitory effects and promoting axonal regeneration [45]. Tian
and co-workers were the first to study the controlled release of
anti-NgR in HA hydrogels by regulating the pH [46], and their
further
in vitro
and
in vivo
experiments both demonstrated that the
controlled delivery of anti-NgR enhanced adhesion, viability and
neurite extension of dorsal root ganglion on HA hydrogels [47].
The
in vivo
experimental
results showed that anti-NgR-HA hydrogel
could inhibit the formation of glial scarring, support angiogenesis,
and simultaneously promote axonal extension after being implanted
into the lesion region [48, 49].
6.4.3 Delivery of Neural Cells using Hyaluronic Acid-based
Scaffolds
Stem cell therapy is a promising approach for CNS injury. However,
this strategy of transplanting stem cells is currently limited by the
poor cell survival, unwanted cell diffusion and uncontrolled cell
differentiation. Bioactive biomaterial scaffolds have been applied as
cell delivery vehicles to overcome the limitations. The biocompatibility
of HA hydrogels with different neural cells, such as neural progenitor
cells hippocampal neurons and neural stem cells (NSC), was widely
investigated, which indicates their promising ability to deliver neural
cells to lesion sites of brain tissue to facilitate axonal regeneration
and functional recovery.
The adhesion and proliferation of NSC could be promoted by
the incorporation of PLGA microspheres encapsulating vascular
endothelial growth factor and BDNF into HA hydrogels [50]. After
5 days of culture, neurites extended along the scaffold and formed an
extensive network, along with their promoted proliferation compared
with the negative controls. The NSC-HA-PLL-anti-NgR complex
was implanted into infarction lesions of rat brain to induce neural
regeneration. It is quite impressive and inspiring that the results
demonstrated that NSC within the HA scaffolds were able to survive
for up to 24 weeks after implantation.
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