Local Administration of Insulin-like Growth Factor I into Silicon Rubber Chamber Improves Peripheral Nerve Repair in Rats

Abstract

p> Introduction: Organ reinnervation and functional recovery following peripheral nerve injury still remains a major challenge and return of functional recovery to the preinjured level rarely occurs.The aim was to evaluate the effect of locally administered insulin-like growth factor (IGF I) on nerve regeneration.

Methods: Eighty male white Wistar rats were divided into four groups (n = 20), randomly: Intransected group (TC), left sciatic nerve was transected and stumps were fixed in the adjacent muscle.In treatment group defect was bridged using a silicone conduit (SIL/IGF) and filled with 10 μL IGF I (100 ng/kg). In silicone graft group (SIL), the graft was filled with phosphate-buffered saline alone. In shamoperated group (SHAM), sciatic nerve was exposed and manipulated. Each group was subdivided into three subgroups of five animals each and studied 4, 8 and 12 weeks after surgery.

Results: Behavioral testing, sciatic nerve functional study, gastrocnemius muscle mass and morphometric indices confirmed faster recovery of regenerated axons in SIL/IGF than in SIL group (p< 0.05). In immunohistochemistry, location of reactions to S-100 in SIL/IGF was clearly more positive than that in SIL group.

Conclusion: When loaded in a silicone graft, IGF I accelerated and improved functional recovery and morphometric indices of sciatic nerve. Thus, dose–response studies should be conducted for IGF I to determine the combination of the graft and the compound that achieve maximal efficacy in nerve transection models.</p

Full text

Journal of Surgery and Surgical Research
Citation: Mohammadi R, Masoumi-Verki M, Ahsan S, Amini K (2015) Local Administration of Insulin-like Growth Factor I into Silicon Rubber Chamber
Improves Peripheral Nerve Repair in Rats. J Surg Surgical Res 1(1): 004-010. DOI: 10.17352/2454-2968.000002 004
Abstract
Introduction: Organ reinnervation and functional recovery following peripheral nerve injury still
remains a major challenge and return of functional recovery to the preinjured level rarely occurs.
The aim was to evaluate the effect of locally administered insulin-like growth factor (IGF I) on nerve
regeneration.
Methods: Eighty male white Wistar rats were divided into four groups (n = 20), randomly: In
transected group (TC), left sciatic nerve was transected and stumps were xed in the adjacent muscle.
In treatment group defect was bridged using a silicone conduit (SIL/IGF) and lled with 10 µL IGF I (100
ng/kg). In silicone graft group (SIL), the graft was lled with phosphate-buffered saline alone. In sham-
operated group (SHAM), sciatic nerve was exposed and manipulated. Each group was subdivided into
three subgroups of ve animals each and studied 4, 8 and 12 weeks after surgery.
Results: Behavioral testing, sciatic nerve functional study, gastrocnemius muscle mass and
morphometric indices conrmed faster recovery of regenerated axons in SIL/IGF than in SIL group (p
< 0.05). In immunohistochemistry, location of reactions to S-100 in SIL/IGF was clearly more positive
than that in SIL group.
Conclusion: When loaded in a silicone graft, IGF I accelerated and improved functional recovery
and morphometric indices of sciatic nerve. Thus, dose–response studies should be conducted for IGF
I to determine the combination of the graft and the compound that achieve maximal efcacy in nerve
transection models.
It has been reported that using silicone tubes in bridging of
nerve defects could be promising because it is inert and does not
induce extensive scarring or degeneration aer implantation [6].
e advantages like no donor morbidity, availability, aordability
and no foreign reactions make silicone rubber chamber an attractive
alternative compared to other standard gras [7]. It has been
demonstrated that silicone rubber tubes are well tolerated in humans
even aer 3 years of implantation [8]. Silicone chambers are used as
standard experimental model to study the nerve regeneration process
[9].
Neurotrophic factors are a family of growth factors that support
and inuence the growth and regenerative capacity of neurons. ese
substances are produced by tissues during development and direct the
formation of the brain and spinal cord and their connections to target
organs such as muscle [10-12]. In adults IGF-I immunoreactivity is
detectable in the ventral horn, sympathetic and dorsal root ganglia
in the adult rat, and axons and Schwann cells of the sciatic nerve
[13,14]. During development, both motor and sensory neurons also
respond to IGF-I and -II with increased neurite outgrowth [14,15-18].
Schwann cell is an essential cellular component of peripheral nerve
and a source of IGF aer nerve injury. IGFs are also important factors
in Schwann cell biology. IGF-I is a potent mitogen for Schwann
cells in culture [19-21]. IGF-I promotes not only the expression of
Abbreviations
IGF: Insulin-Like Growth Factor
Introduction
Organ reinnervation and functional recovery following peripheral
nerve injury still remains a major challenge and return of functional
recovery to the preinjured level rarely occurs [1]. Peripheral nerve
contains both dendrites and axons which conduct information to
(aerent) or from (eerent) the CNS, respectively. Although the
smallest axons are unmyelinated, most axons in a peripheral nerve
are myelinated with the multiple concentric layers of lipid-rich with
biochemically modifying plasma membrane produced by Schwann
cells. Schwann cells and their endoneurial extracellular matrix play
pivotal roles in the selective promotion of motor and sensory axon
regeneration [2]. When an axon is crushed or severed, changes occur
on both sides of the lesion [3]. Where a gap is present between the
severed ends of the nerve, proliferating Schwann cells emerge from
the stumps (mainly the distal stump) and form series of nucleated
cellular cords (the bands of Bungner) which bridge the interval [4].
e conduits act to guide axons sprouting from the regenerating
nerve end, provide a microenvironment for diusion of neurotrophic
and neurotropic factors secreted by the injured nerve stump, as well
as help protect inltration of brous tissue [5].
Research Article
Local Administration of Insulin-like
Growth Factor I into Silicon Rubber
Chamber Improves Peripheral Nerve
Repair in Rats
Rahim Mohammadi1*, Masoume
Masoumi-Verki1, Sima Ahsan1 and
Keyvan Amini2
1Department of Surgery and Diagnostic Imaging,
Faculty of Veterinary Medicine, Urmia University,
Nazloo Road, Urmia, 57153 1177, Iran
2Department of Veterinary Pathology, Western
College of Veterinary Medicine, University of
Saskatchewan, 52 Campus Drive, Saskatoon,
Saskatchewan S7N 5B4, Canada
Dates: Received: 06 March, 2015; Accepted: 11
April, 2015; Published: 13 April, 2015
*Corresponding author: Rahim Mohammadi,
Department of Surgery and Diagnostic Imaging,
Faculty of Veterinary Medicine, Urmia University,
Nazloo Road, Urmia, 57153 1177, Iran, Tel: +98
443 2770508; Fax: +98 443 277 1926; E-mail:
www.peertechz.com
ISSN: 2454-2968
Keywords: Peripheral nerve repair; Sciatic; Insulin-
like growth factor I; Local

Citation: Mohammadi R, Masoumi-Verki M, Ahsan S, Amini K (2015) Local Administration of Insulin-like Growth Factor I into Silicon Rubber Chamber
Improves Peripheral Nerve Repair in Rats. J Surg Surgical Res 1(1): 004-010. DOI: 10.17352/2454-2968.000002
Mohammadi et al. (2015)
005
myelin proteins such as Protein zero but also segmental myelination
of dorsal root ganglia axons in culture, including the formation of
nodes of Ranvier [22]. Promising results regarding benecial eect of
IGF I on peripheral nerve regeneration is not supported by functional
tests, to the best knowledge of the authors, which play a crucial role in
assessment of functional nerve recovery.
Aimed to study local eects of IGF I on peripheral nerve
regeneration, the present study was designed to determine if local
IGF could in fact reduce dysfunction aer nerve injury in the rat
sciatic nerve transection model. Assessment of the nerve regeneration
was based on behavioral, functional, histomorphometric and
immuohistochemical (Schwann cell detection by S-100 expression)
criteria 4, 8 and 12 weeks aer surgery.
Materials and Methods
Study design and animals
Eighty male Wistar rats weighing approximately 300g were
divided into four experimental groups (n = 15), randomly: sham-
operation group as normal control (SHAM), transected control (TC),
silicone conduit (SIL) and IGF treated group (SIL/IGF). Each group
was further subdivided into three subgroups of ve animals each
and surveyed 4, 8 and 12 weeks aer surgery. Two weeks before and
during the experiments, the animals were housed in individual plastic
cages with an ambient temperature of (23±3) °C, stable air humidity
and a natural day/night cycle. e rats had free access to standard
rodent laboratory food and tap water. All measurements were made
by two blinded observers unaware of the analyzed groups.
Surgical procedure
Animals were anesthetized by intraperitoneal administration of
ketamine-xylazine (ketamine 5%, 90mg/kg and xylazine 2%, 5mg/
kg). e procedure was carried out based on the guidelines of the
Ethics Committee of the International Association for the Study of
Pain [23]. e University Research Council approved all experiments.
Following surgical preparation in the sham-operation group, the
le sciatic nerve was exposed through a gluteal muscle incision and
aer careful homeostasis the muscle was sutured with resorbable 4/0
sutures, and the skin with 3/0 nylon. In TC group, the le sciatic nerve
was transected proximal to the tibio-peroneal bifurcation where a
7mm segment was excised, leaving a 10mm gap due to retraction of
nerve ends. Proximal and distal stumps were xed in the adjacent
muscle with 10/0 nylon epineurial suture. No gra was interposed
between the stumps. In control group (SIL), the le sciatic nerve was
exposed the same way, transected proximal to the tibio-peroneal
bifurcation where a 7 mm segment was excised, leaving a gap about
10 mm due to retraction of the nerve ends. e proximal and distal
stumps were each inserted 2 mm into the conduit and two 10/0 nylon
sutures were placed at each end of the cu to x the tube in place and
leave a 10-mm gap between the stumps. e silicone tube was lled
with 10 µL phosphate buered solution. Sterile Vaseline was used
to seal the ends of the tubes to avoid leakage. In IGF treated group
(SIL/IGF) the silicone gra was lled with 10 μl IGF I (100ng/kg).
All surgical procedures were carried out by the same surgeon, using a
sterile microsurgical technique. Aer surgery had carried out animals
were housed in groups of ve per cage under the same conditions
mentioned above. e animals were anesthetized and euthanized with
transcardiac perfusion of a xative containing 2% paraformaldehyde
and 1%glutaraldehyde buer (pH 7.4) 4, 8 and 12 weeks aer surgery.
Behavioral Testing
Functional recovery of the nerve was assessed using the Basso,
Beattie, and Bresnahan (BBB) locomotor rating scale for rat hind
limb motor function [24]. Although BBB is widely used to assess
functional recovery in spinal cord injured animals, however, it has
been demonstrated that it could be most useful in assessment of never
repair processes in peripheral nerve injuries [1]. Scores of 0 and 21
were given when there were no spontaneous movement and normal
movement, respectively. A score of 14 shows full weight support and
complete limbs coordination. BBB recordings were performed by a
trained observer who was blinded to the experimental design. e
testing was performed in a serene environment. e animals were
observed and assessed within a course of a 4-minute exposure to an
open area of a mental circular enclosure. BBB scores were recorded
once before surgery in order to establish a baseline control and again
weekly thereaer to assess functional recovery during 12 weeks.
Functional assessment of reinnervation
Sciatic functional index (SFI): Walking track analysis was
performed 4, 8 and 12 weeks aer surgery based on the method
of others [16]. e lengths of the third toe to its heel (PL), the rst
to the h toe (TS), and the second toe to the fourth toe (IT) were
measured on the experimental side (E) and the contralateral normal
side (N) in each rat. e sciatic function index (SFI) of each animal
was calculated by the following formula:
SFI = -38.3× (EPL-NPL)/NPL+109.5× (ETS-NTS)/NTS +13.3×
(EIT-NIT)/NIT-8.8
In general, SFI oscillates around 0 for normal nerve function,
whereas around -100 SFI represents total dysfunction. SFI was
assessed in the NC group and the normal level was considered as 0.
SFI was a negative value and a higher SFI meant the better function
of the sciatic nerve.
Static sciatic index (SSI): SSI is a time-saving digitized static
footprint analysis described by others [25]. A good correlation
between the traditional SFI and the newly developed static sciatic
index (SSI) and static toe spread factor (TSF), respectively, has been
reported by others [25]. e SSI is a time-saving and easy technique
for accurate functional assessment of peripheral nerve regeneration
in rats and is calculated using the static factors, not considering the
print length factor (PL), according to the equation:
SSI = [(108.44 × TSF) + (31.85 × ITSF)] − 5.49
Where:
TSF = (ETS-NTS)/NTS
ITSF = (EIT-NIT)/NIT
Like SFI, an index score of 0 was considered normal and an
index of −100 indicated total impairment. When no footprints were
measurable, the index score of −100 was given.

Citation: Mohammadi R, Masoumi-Verki M, Ahsan S, Amini K (2015) Local Administration of Insulin-like Growth Factor I into Silicon Rubber Chamber
Improves Peripheral Nerve Repair in Rats. J Surg Surgical Res 1(1): 004-010. DOI: 10.17352/2454-2968.000002
Mohammadi et al. (2015)
006
Muscle mass
Recovery assessment was also indexed using the weight ratio of
the gastrocnemius muscles 12 weeks aer surgery. Immediately aer
sacricing of animals, gastrocnemius muscles were dissected and
harvested carefully from intact and injured sides and weighed while
still wet, using an electronic balance.
Histological preparation and morphometric studies
Nerve mid-substance in SIL group, nerve mid-substance in
IGF I treated group, midpoint of normal sciatic nerve (Sham) and
regenerated mid substance of TC group were harvested and xed
with glutaraldehyde 2.5%. ey were post xed in OsO4 (2%, 2 h),
dehydrated through an ethanol series and embedded in Epon. e
nerves were cut in 5 μm in the middle, stained with toluidine blue
and examined under light microscopy. Morphometric analysis was
carried out using an image analyzing soware (Image-Pro Express,
version 6.0.0.319, Media Cybernetics, Silver Springs, MD, USA). Equal
opportunity, systematic random sampling and two-dimensional
dissector rules were followed in order to cope with sampling-related,
ber-location-related and ber-size related biases [26].
Immunohistochemical analysis
In this study, anti-S-100 (1:200, DAKO, USA) was used as
marker for myelin sheath. Specimens were post xed with 4%
paraformaldehyde for 2h and embedded in paran. Prior to
immunohistochemistry nerve sections were dewaxed and rehydrated
in PBS (pH 7.4). en the nerve sections were incubated with
0.6% hydrogen peroxide for 30 minutes. To block non-specic
immunoreactions the sections were incubated with normal swine
serum (1:50, DAKO, USA). Sections were then incubated in S-100
protein antibody solution for 1h at room temperature. ey were
washed three times with PBS and incubated in biotynilated anti-
mouse rabbit IgG solution for 1h. Horseradish peroxidase-labelled
secondary antibody was applied for 1 h. Aer that all sections
were incubated with 3,3’- diaminobenzidine tetrahydrochloride
chromogene substrate solution (DAB, DAKO, USA) for 10 min.
e results of immunohistochemistry were examined under a light
microscope.
Statistical Analysis
e results were expressed as means ± SD. Statistical analyses
were performed using PASW 18.0 (SPSS Inc., Chicago, IL, USA).
Model assumptions were evaluated by examining the residual plot.
Results were analyzed using a factorial ANOVA with two between-
subjects factors. Bonferroni test for pairwise comparisons was used
to examine the eect of time and treatments. e dierences were set
at P< 0.05.
Results
Behavioral Testing
BBB recovery: In order to assess hind limb recovery the open
eld locomotor was used. Figure 1 shows BBB scores compared to
the baseline. All experimental groups, except for sham, showed the
greatest degree of functional decit one week aer surgery. e IGF I
treated group showed signicant improvement in locomotion of the
operated limb compared to the SIL group during the study period
(P< 0.05).
Recovery of sciatic nerve function
SFI outcome: Figure 2 shows sciatic function index (SFI) values
in all four experimental groups. Prior to surgery, SFI values in all
groups were near zero. Aer the nerve transection, the mean SFI
decreased to -100 due to the complete loss of sciatic nerve function
in all animals. At the end of the study period, animals of IGF I group
achieved a mean value for SFI of -45. 8 ± -2.36 where as in group
SIL a mean value of -63.3 ± -3.14 was found. e statistical analyses
revealed that the recovery of nerve function was signicantly (P <
0.05) dierent between SIL/IGF and SIL groups and application
of the IGF I in silicone conduit signicantly accelerated functional
recovery in the course of time.
SSI outcome: Changes in SSI were similar to those observed
in SFI, indicating signicant decit following the sciatic nerve
transection (Figure 3). Changes in SSI were signicant at weeks 4,
8 and 12 of recovery (P < 0.05). e contrasts indicate SSI values in
group SIL/IGF at week 12 to dier signicantly from those obtained
from SIL, a trend also noticed for SFI (P < 0.05).
Muscle mass measurement
e mean ratios of gastrocnemius muscle weight were measured
at the end of the study period. ere was a statistically signicant
dierence between the muscle weight ratios of the SIL/IGF and SIL
groups (P < 0.05). e results showed that in the IGF I treated group,
the muscle weight ratio was larger than in the SIL group, and weight
loss in the gastrocnemius muscle was ameliorated by IGF I local
administration (Figure 4).
Histological and Morphometric ndings
e IGF I treated group presented signicantly greater nerve ber,
axon diameter, and myelin sheath thickness during study period,
compared to SIL animals (P < 0.05). Sham-operation group presented
signicantly greater nerve ber and axon diameter, and myelin sheath
thickness compared to SIL/IGF and SIL groups animals (Figures
5-8). In case of myelin thickness there was no signicant dierence
between SIL/IGF and SIL groups, morphometrically (P>0.05).
Figure 1: BBB score for all experimental groups. Local administration of IGF
I with artery grafting gave better scores than in SIL group. Standard error at
each data point is shown with bars.

Citation: Mohammadi R, Masoumi-Verki M, Ahsan S, Amini K (2015) Local Administration of Insulin-like Growth Factor I into Silicon Rubber Chamber
Improves Peripheral Nerve Repair in Rats. J Surg Surgical Res 1(1): 004-010. DOI: 10.17352/2454-2968.000002
Mohammadi et al. (2015)
007
nerve during the study period. Le gastrocnemius muscle weight
was signicantly greater in the SIL/IGF group than in the SIL group,
indicating indirect evidence of successful end organ reinnervation in
the IGF I treated animals. At week 12 quantitative morphometrical
indices of regenerated nerve bers showed signicant dierences
between the SIL and SIL/IGF groups, indicating a benecial eect of
local application of IGF I on the nerve regeneration.
Although both morphological and functional data have been
used to assess neural regeneration aer induced crush injuries,
the correlation between these two types of assessment is usually
poor [27-29]. Classical and newly developed methods of assessing
nerve recovery, including histomorphometry, retrograde transport
of horseradish peroxidase and retrograde uorescent labeling
[29] do not necessarily predict the reestablishment of motor and
sensory functions [28,30-32]. Although such techniques are useful
Sciatic nerve function index
Experimental groups
SH AM TC SI L SIL/IGF
-100
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
Figure 2: Box-and-whisker plots of sciatic nerve function index values in each
experimental group during the study period. Local administration of IGF I with
artery grafting gave better results in functional recovery of the sciatic nerve
than in SIL group.
Figure 3: Bar graph indicating static sciatic index (SSI) values in each
experimental group during the study period. Local administration of IGF I
with inside-out artery grafting gave better results in functional recovery of
the sciatic nerve than in SIL group. Data are presented as mean ± SD. * P <
0.05 vs SIL group.
Immunohistochemistry
Immunoreactivity to S-100 protein was extensively observed in
the cross sections of regenerated nerve segments. e expression of
S-100 protein signal was located mainly in the myelin sheath. e
axon also showed a weak expression indicating that Schwann cell-like
phenotype existed around the myelinated axons (Figure 8). In both
SIL/IGF and SIL groups, the expression of S-100 and the ndings
resembled those of the histological evaluations.
Discussion
e results of the present study showed that application of IGF I
in a silicone gra resulted in faster functional recovery of the sciatic
Figure 4: Gastrocnemius muscle weight measurement. The gastrocnemius
muscles of both sides (operated left and unoperated right) were excised and
weighed in the experimental groups at 12 weeks after surgery. Data are
presented as mean ± SE. * P < 0.05 vs SIL group.
Figure 5: The graph shows the quantitative results of ber counting. The
mean number of nerve bers in SHAM group was nearly 8267 ± 234 (mean ±
SE). Both groups of SIL and SIL/IGF showed the lower number of bers than
the sham-operated group even at the end of the study period.

Citation: Mohammadi R, Masoumi-Verki M, Ahsan S, Amini K (2015) Local Administration of Insulin-like Growth Factor I into Silicon Rubber Chamber
Improves Peripheral Nerve Repair in Rats. J Surg Surgical Res 1(1): 004-010. DOI: 10.17352/2454-2968.000002
Mohammadi et al. (2015)
008
Figure 6: The graph shows the quantitative results of mean diameter of
nerves bers. The mean diameter of nerve bers in SHAM group was nearly
12.4 ± 0.14 (mean ± SE). Both groups of SIL and SIL/IGF showed the lower
mean diameter of nerve bers than the sham-operated group even at the end
of the study.
Figure 7: The graph shows the quantitative results of mean thickness of
myelin sheath. The mean thickness of myelin sheath in SHAM group was
nearly 2.5 ± 0.03 (mean ± SE). Both groups of SIL and SIL/IGF showed the
lower mean diameter of axons than the sham-operated group even at the end
of the study period.
Figure 8: Immunohistochemical analysis of the regenerated nerves 16 weeks
after surgery from (A) middle cable TC, (B) SIL, (C) SIL/IGF and (D) SHAM.
There is clearly more positive staining of the myelin sheath-associated protein
S- 100 (arrows) within the periphery of nerve, indicating well organized
structural nerve reconstruction in IGF I treated nerve compared to that of the
SIL. Scale bar: 10μm.
in studying the nerve regeneration process, they generally fail in
assessing functional recovery [28]. erefore, research on peripheral
nerve injury needs to combine both functional and morphological
assessment. Castaneda et al. [32] suggested that arrival of sprouts from
the proximal stump at the distal nerve stump does not necessarily
imply recovery of nerve function. Information taken from BBB scale
may be invaluable in evaluation of peripheral nerve process. Results
of the present study showed that the IGF treated animals had been
improved in locomotion of the operated limb compared to the SIL
group during the study period. Walking track analysis has frequently
been used to reliably determine functional recovery following nerve
repair in rat models [16,30].
A wide variety of materials have been used to produce nerve
guides, including non-biodegradable and biodegradable materials.
Because of its inert and elastic properties, the silicon tube was one
of the rst and most frequently used to bridge the transected nerves
[33].
e accumulation of IGF-I aer peripheral nerve damage could
be the result of disrupted axonal transport or a local therapeutic
response. e relevance of post injury up-regulation of IGF has
been addressed in multiple studies. Others in an experimental
study without being supported by functional tests concluded that
local infusion of IGF-I at appropriate concentration promotes
regeneration of a peripheral nerve [34]. Kanje et al. [35] reported
that IGF-I signicantly increased axonal regeneration by 49% in a
rat sciatic nerve crush/ transection model. is eect was unique to
IGF-I because nerve growth factor treatment had no eect. e in
vivo mechanisms of IGF action are assumed to be similar to those
activated in primary neuronal cultures. Studies applying pathway-
specic inhibitors are not available, however, antibodies to IGF-I
but not nerve growth factor or insulin have completely blocked the
ability of IGF-I to promote axonal regrowth [35,36]. Further work
by others has examined the eects of a preconditioning transection
that was performed before nerve crush [37]. Under these conditions,
regeneration was more robust than crush alone. is augmented
regeneration was blocked by inhibitors of protein or RNA synthesis
or retrograde axonal transport [37]. Perfusion of IGF-I is able to
overcome the eects of cycloheximide (protein synthesis inhibitor),
indicating that locally produced IGF-I is retrogradely transported to
the cell body in which it exerts its positive eects [37].

Citation: Mohammadi R, Masoumi-Verki M, Ahsan S, Amini K (2015) Local Administration of Insulin-like Growth Factor I into Silicon Rubber Chamber
Improves Peripheral Nerve Repair in Rats. J Surg Surgical Res 1(1): 004-010. DOI: 10.17352/2454-2968.000002
Mohammadi et al. (2015)
009
Even though our preliminary study shows the neuroprotective
action of local IGF I in peripheral nerve injuries, determining the
molecular mechanisms leading to the neuroprotective action remains
needs to be investigated. We have not given the histological and
molecular evidence for neuroprotective action of IGF I. is may
be considered as a limitation to our study. erefore, the authors
stress that the aim of the current investigation was to evaluate a
single local dose and clinical treatment potential of IGF I on nerve
regeneration including functional assessments of the nerve repair,
a case not considered in previous studies. e results of the present
study indicated that a single Local administration of IGF I at the site
of transected nerve could be of benet aer artery gra tubulization.
Detailed mechanism of neuroprotective action remains to be
investigated.
Conclusion
e present study demonstrated that a single local application of
IGF I could accelerated functional recovery aer transection of sciatic
nerve. us, dose–response studies should be conducted for IGF I
to determine the combination of the gra and the compound that
achieve maximal ecacy in nerve transection models.
Acknowledgement
e authors would like to thank Mr Matin and Valinezhad for
their technical expertise.
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Citation: Mohammadi R, Masoumi-Verki M, Ahsan S, Amini K (2015) Local Administration of Insulin-like Growth Factor I into Silicon Rubber Chamber
Improves Peripheral Nerve Repair in Rats. J Surg Surgical Res 1(1): 004-010.
Mohammadi et al. (2015)
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unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
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