Biology Reference
In-Depth Information
While axons in the rodent peripheral nervous system regenerate at a
speed of 2-3 mm/day, so that relatively short distances are rapidly bridged
by growing axons, human peripheral nerve injuries are followed by a
slower rate of regeneration (1 mm/day). Given the fact that some motor
and sensory axons projecting into the lower limb may reach or exceed a
length of 1 m, the regeneration and reinnervation of peripheral targets
may clearly be an extremely slow process. The slow regeneration in human
peripheral nerves is further hampered by the predegenerative process occur-
ring in the distal parts of the nerve to be occupied by regenerating fibers
(
Gordon, 2010; Gordon et al., 2009
).
In view of the long recovery and rehabilitation process after injuries to
peripheral nerves, there is a great need for the development of procedures
that promote peripheral nerve regeneration in humans and thereby decrease
the related social and health-care costs. While the effects of shock waves on
wound healing, (
Schaden et al., 2007
), bone regeneration (
Ogden, Alvarez,
Levitt, Cross, &Marlow, 2001
), and the integration of skin grafts (
Kuo et al.,
2009; Stojadinovic et al., 2008
) have been extensively studied, very little is
known as concerns its effects on peripheral nerve regeneration (
Hausner
et al., 2012; Wu, Lun, Chen, & Chong, 2007
).
3. PRESUMED BIOLOGICAL EFFECTS OF ESWT
Shock waves are mechanical events that can stimulate tissues and espe-
cially cells. The conversion of physical forces into biochemical signals is a
fundamental process required for the development and the physiology of
organisms. This process is referred to as mechanotransduction. Physical
forces exert a direct influence on protein folding, and force-induced effects
on the three-dimensional structures of proteins are therefore involved in a
general mechanism through which the activities of enzymes or the interac-
tions between proteins may lead to signal modification (
Orr, Helmke,
Blackmann, & Schwartz, 2006
). The manner in which ESWT-induced
mechanotransduction is manifested in target cells and tissues is still not clear.
There are a number of proved facts or theories concerning the cascade of
actions stemming from shock wave treatment and resulting in angiogenesis
or neovascularization (
Sadoun and Reed, 2003; Stojadinovic et al., 2008;
Wang et al., 2004
), anti-inflammatory effects (
Davis et al., 2009
), the release
of growth factors (
Hausdorf et al., 2011
), and the activation of progenitor
cells and stem cells (
Mittermayer et al., 2012; Sadoun and Reed, 2003
).
