Genipin-Cross-Linked Chitosan Nerve Conduits Containing TNF-a
Inhibitors for Peripheral Nerve Repair
Key Laboratory of Neuroregeneration of Jiangsu and Ministry of Education, Co-Innovation Center of Neuroregeneration,
Nantong University, Nantong 226001, China;
Department of Life Sciences of Medical School, Nantong University,
Nantong 226001, China; and
Department of Pathophysiology of Medical School, Nantong University, Nantong 226001, China
(Received 23 November 2017; accepted 21 March 2018; published online 30 March 2018)
Associate Editor Michael Gower oversaw the review of this article.
Abstract—Tissue engineered nerve grafts (TENGs) are con-
sidered a promising alternative to autologous nerve grafting,
which is considered the ‘‘gold standard’’ clinical strategy for
peripheral nerve repair. Here, we immobilized tumor necrosis
factor-a (TNF-a) inhibitors onto a nerve conduit, which was
introduced into a chitosan (CS) matrix scaffold utilizing
genipin (GP) as the crosslinking agent, to fabricate CS-GP-
TNF-a inhibitor nerve conduits. The in vitro release kinetics
of TNF-a inhibitors from the CS-GP-TNF-a inhibitor nerve
conduits were investigated using high-performance liquid
chromatography. The in vivo continuous release proﬁle of the
TNF-a inhibitors released from the CS-GP-TNF-a inhibitor
nerve conduits was measured using an enzyme-linked
immunosorbent assay over 14 days. We found that the
amount of TNF-a inhibitors released decreased with time
after the bridging of the sciatic nerve defects in rats.
Moreover, 4 and 12 weeks after surgery, histological analyses
and functional evaluations were carried out to assess the
inﬂuence of the TENG on regeneration. Immunochemistry
performed 4 weeks after grafting to assess early regeneration
outcomes revealed that the TENG strikingly promoted
axonal outgrowth. Twelve weeks after grafting, the TENG
accelerated myelin sheath formation, as well as functional
restoration. In general, the regenerative outcomes following
TENG more closely paralleled ﬁndings observed with autol-
ogous grafting than the use of the CS matrix scaffold.
Collectively, our data indicate that the CS-GP-TNF-a
inhibitor nerve conduits comprised an elaborate system for
sustained release of TNF-a inhibitors in vitro, while studies
in vivo demonstrated that the TENG could accelerate
regenerating axonal outgrowth and functional restoration.
The introduction of CS-GP-TNF-a-inhibitor nerve conduits
into a scaffold may contribute to an efﬁcient and adaptive
immune microenvironment that can be used to facilitate
peripheral nerve repair.
Keywords—Tissue engineered nerve grafts (TENGs), Tumor
necrosis factor-a (TNF-a), Peripheral nerve regeneration,
Genipin, Schwann cells.
Due to current economic growth and lifestyle
changes, there is a huge unmet medical need, both
globally and in China, for treating chronic degenera-
tive diseases and acute traumas. Approximately 5% of
wounds in the extremities may be associated with
peripheral nerve injury.
Peripheral nerve injury has a
profound impact on daily life, as it can lead to im-
paired sensory and motor function, which often
necessitate surgical intervention,especially in cases
where the defects are greater than a few millimeters in
For short nerve gaps in small-diameter nerves,
end-to-end suturing (nerve coaptation) is the preferred
strategy to repair the defect. Autologous nerve grafting
is recognized as the ‘‘gold standard’’ clinical strategy
for peripheral nerve injuries larger than 3 cm, although
it is commonly associated with donor site morbidity
and is not widely available.
The peripheral nervous
system (PNS) is typically considered to have a greater
capacity for axonal functional recovery after injury
than the central nervous system (CNS).
complete axonal transections with relatively larger gap
distances, surgical interventions in patients are rou-
tinely needed for desirable functional recovery.
Address correspondence to Yumin Yang and Xin Tang, Key
Laboratory of Neuroregeneration of Jiangsu and Ministry of
Education, Co-Innovation Center of Neuroregeneration,
Nantong University, Nantong 226001, China. Electronic mails:
Li Zhang and Weijia Zhao have contributed equally to this work.
Annals of Biomedical Engineering, Vol. 46, No. 7, July 2018 (
2018) pp. 1013–1025
2018 Biomedical Engineering Society