Biology Reference
In-Depth Information
regeneration-promoting effect after 10 mm autotransplantation in the rat
femoral nerve model has been described (
Huang et al., 2009
).
Highlighting the importance of a defined stimulation protocol, low-
frequency stimulation for 1 h has been demonstrated to be as effective as
continuous stimulation over 2 weeks for motoneurons (
Al-Majed,
Neumann, et al., 2000
), but for sensory neurons, the positive effect of accel-
erated axonal regeneration across a nerve repair site is abolished when the
stimulation period is extended over 1 h (
Geremia, Gordon, Brushart,
Al-Majed, & Verge, 2007
). Furthermore, chronic electrical stimulation
(1 h daily) was described to be less effective than brief acute electrical stim-
ulation with regard to muscle reinnervation and axonal regeneration
(
Asensio-Pinilla, Udina, Jaramillo, & Navarro, 2009
).
The regeneration-promoting effects of the acute direct electrical stimu-
lation paradigm has also been successfully tested in animal models for
long-gap repair. Our own studies clearly demonstrated that the brief,
low-frequency direct stimulation protocol is sufficient to accelerate long-
distance regeneration of motor and sensory axons resulting in an increase
of functional regeneration especially after nerve autotransplantation
(13-mm gap lengths) in rats (
Haastert-Talini et al., 2011
).
But also for 15-mm rat sciatic nerve gap reconstruction with longitudi-
nally oriented microchannels, it has been shown that axonal and motor
regeneration rates after electrical stimulation reach levels comparable to
the gold standard nerve autotransplantation without stimulation (
Huang,
Lu, et al., 2010
).
Tissue engineering of peripheral nerves is an attempt of high actuality
(
Grothe et al., 2012
) and electrical stimulation may provide a valuable
cotreatment to it.
2.3. Electrical stimulation via the synthetic nerve graft
Besides the transcutaneous/percutaneous or direct application of electrical
stimuli to the reconstructed nerve also induction of an electrical field along
the nerve gaps bridged with synthetic tubes has been already tested decades
ago. Electric fields along nerve guidance tubes can be elicited by the use of
piezoelectric tube material. This material generates transient electrical char-
ges upon deformation (
Aebischer, Valentini, Dario, Domenici, Guenard,
et al., 1987
). Bridging 4-mm nerve gaps in the mouse with electrically poled
piezoelectric tubes significantly increased regeneration of myelinated axons
in comparison to bridging the defects with electrically inert unpoled tubes
