Biology Reference
In-Depth Information
ΒΌ
(DD
70%) is fully degradable (
Kofuji, Ito, Murata, & Kawashima, 2001;
Tomihata & Ikada, 1997
). In recent years, chitosan, either alone or in com-
bination with other biomaterials (
Table 1.1
), adhesion peptides (
Table 1.2
),
supportive cells (
Table 1.3
), or growth factors (
Table 1.4
), has been widely
used for spinal cord repair.
Ex vivo
and
in vivo
SCI models demonstrate that chitosan is able to restore
compromised membrane integrity following spinal cord trauma, reduces
injury-mediated production of reactive oxygen species (ROS), and restricts
continuing lipid peroxidation, displaying a potent neuroprotective role even
though it did not show any ROS, or acrolein, scavenging ability (
Cho et al.,
2010
). Yet, the use of chitosan has therapeutic potential through site-specific
delivery following traumatic spinal cord and head injury (
Cho et al., 2010
).
To increase the potential for axonal regeneration and functional recovery,
implantation of autograft combined with biomaterials appears to be a prom-
ising strategy too.
Nomura, Baladie, et al. (2008)
have shown that intracavitary
implantation of chitosan guidance channels containing peripheral nerve grafts
after subacute SCI resulted in a thicker bridge containing a larger number of
myelinated axons compared with chitosan channels alone. Peripheral nerve-
filled chitosan conduits showed an excellent biocompatibility with the adja-
cent neural tissue with no signs of degradation and minimal tissue reaction at
14 weeks after implantation (
Nomura, Baladie, et al., 2008
).
3.1. Surface modification of chitosan conduits for CNS repair
A promising strategy for facilitating nerve regeneration is the combination of
biomaterials with adhesion molecules (
Table 1.2
), such as laminin (
Cheng
et al., 2007; Lemmon, Burden, Payne, Elmslie, & Hlavin, 1992
), L1
(
Lemmon et al., 1992
), N-cadherin (
Lemmon et al., 1992
), and collagen
(
Li et al., 2009
). These molecules may be positioned in the inner portion
of the tube device in order to guide neurite growth. Chitosan conduits
enriched with adhesion molecules have been already used
in vivo
with the
goal of better directing the repair of damaged axons following SCI. Biode-
gradable porous chitosan nerve conduits, filled with semifluid type
I collagen, have been developed using lyophilizing and wire-heating process
(
Li et al., 2009
) and implanted into the injured spinal cord of a rat model.
Results showed that collagen serves as a directional guide to facilitate cor-
rectly aligned axon regrowth and enhances nerve regeneration across a
gap. Yet, the chitosan tube blocked the invasion of glial scar tissue into
the lesion site (
Li et al., 2009
).
