Neurol India Home 
 

ORIGINAL ARTICLE
Year : 2021  |  Volume : 69  |  Issue : 2  |  Page : 318--325

Efficacy of Silicone Conduit in the Rat Sciatic Nerve Repair Model: Journey of a Thousand Miles

Suyash Singh1, Arun Kumar Srivastava2, Atul K Baranwal3, Ankur Bhatnagar4, Kuntal Kanti Das2, Sushila Jaiswal5, Sanjay Behari2,  
1 Department of Neurosurgery, All India Institute of Medical Sciences, Raebareli, Uttar Pradesh, India
2 Department of Neurosurgery, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
3 Veterinary Scientist, Animal House, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
4 Department of Plastic and Reconstruction Surgery, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India
5 Department of Pathology, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, Uttar Pradesh, India

Correspondence Address:
Arun Kumar Srivastava
Department of Neurosurgery, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow, Uttar Pradesh
India

Abstract

Background: A lot of options have been tried for bridging the two ends of the injured nerves. Researchers have used decellularized nerve grafts, artificial materials and even nerve growth factors to augment functional recovery. These materials are either costly or inaccessible in developing world. Objective: The study aimed to evaluate the efficacy of the silicone conduit in a rat sciatic nerve injury model. Materials and Methods: 24 healthy Sprague–Dawley (SD) rats (250-300 grams; 8-10 weeks) were used and right sciatic nerve was exposed; transected and re-anastomosed by two different methods in 16 rats. In control group, n = 8 (Group I) the sciatic nerve was untouched; Group II (reverse nerve anastomosis, n = 8): 1-centimeter of nerve was cut and re-anastomosed by using 10-0 monofilament suture; Group III (silicone conduit, n = 8) 1-centimeter nerve segment was cut, replaced by silicone conduit and supplemented by fibrin glue]. Evaluation of nerve recovery was done functionally (pain threshold and sciatic functional index) over 3 months and histologically and electron microscopically. Results: Functional results showed a trend of clinical improvement in Group III and II but recovery was poor and never reached up to normal. Histopathological and electron microscopic results showed an incomplete axonal regeneration in Groups II and III. Psychological analyses showed that no outwards signs of stress were present and none of the rats showed paw biting and teeth chattering. Conclusion: The silicone conduit graft may be an economical and effective alternative to presently available interposition grafts, however for short segments only.



How to cite this article:
Singh S, Srivastava AK, Baranwal AK, Bhatnagar A, Das KK, Jaiswal S, Behari S. Efficacy of Silicone Conduit in the Rat Sciatic Nerve Repair Model: Journey of a Thousand Miles.Neurol India 2021;69:318-325


How to cite this URL:
Singh S, Srivastava AK, Baranwal AK, Bhatnagar A, Das KK, Jaiswal S, Behari S. Efficacy of Silicone Conduit in the Rat Sciatic Nerve Repair Model: Journey of a Thousand Miles. Neurol India [serial online] 2021 [cited 2021 Jun 16 ];69:318-325
Available from: https://www.neurologyindia.com/text.asp?2021/69/2/318/314576


Full Text



Traumatic peripheral nerve injury is a devastating event having a significant neurological, economical, psychological and functional impact. A lot of options, both autografts or isografts, have been tried to bridge the two ends of injured nerves.[1] Researchers have used decellularized nerve grafts, artificial materials and even nerve growth factors to augment functional recovery of damaged nerve.[2] Most of these materials are either costly or inaccessible in a developing country. The aim of our study was to provide an immunological safe, cost-effective, neuro-effective, and readily available alternative for the use of interposition graft. Silicone sheets are cheap, readily available and can be transformed into tubes easily.[3] In this article, we showed a comparative analysis of clinical, psychological and histopathological outcomes in a rat sciatic nerve injury model.

 Methodology



Study design

We did a single-center, prospective study to analyze the efficacy of silicone conduit in rat nerve model (2018–2019). This animal experiment was approved by the Institute Animal Ethics Committee with Ethical number PGI/IMP/IAEC/17/27.08.2015. All the animals were kept in the institute vivarium (maintained at standard room temperature and humidity). Pellet feed and Reverse Osmosed (R. O.) treated water was offered ad libitum to animals.

Study design and rationale

Rats were operated in small animal operation theater of vivarium and observed for the next 15 weeks. The timeline of 15 weeks was taken from work of Waitayawinyu et al.[4] He proposed that the rodents' nerve have a higher regenerative capacity, and so, observations beyond 15-weeks may be confounded. Moreover, the macrophages and Schwann cells require nearly 3–6 weeks to reach the injury site and clear the debris.[5] Once the Schwann cells reach to their target, they organize and provide a scaffold for regenerating axons.

Study parameters

Mechanical pain threshold, Sciatic function test, and open field analyses were performed by a two-blinded observers (AKB, SS) unaware of animal grouping details. The efficacy of nerve regeneration was evaluated using the following standardized parameters

Mechanical pain threshold testing [Von Frey hair (VFH) sensitivity test] - Rat's paw was stimulated by a stiff nylon monofilament and 'paw withdrawal' or 'flinch' was observed for. The intensity of pain threshold in incremented by using filaments of different thickness sequentiallyBodyweight gain: Body weight of rats was recorded weekly. It as an indirect marker of altered feeding habits due to pain. As such, a rat in more pain or agony do not prefer to explore and eats less and thereby either do not gain weight or gain less weight as compared to normal age-matched ratSciatic functional index (SFI): It was analyzed using footprint score method. Ipsilateral paw was dabbed gently on in-house made ink-pad and then rat was allowed to walk over open field with white paper floor [Figure 1]. The maximum score was 11, when foot-print strokes of paw was normal and score was zero in case of hind-limb paralysis. The SFI comprises values between –11 (normal functionality) to 0 (complete loss of functionality)Open field analyses and Toe spread pattern: Rats were allowed to walk in guarded open field to analyze animals' gait and development of any behavioral signs. The impression of rat's paw, smeared in ink, was taken in white sheet. The distorted prints were allowed to dry and then analyzed subsequently [Figure 2]Histopathological and Electron microscopy study by single-blinded pathologist (SJ).{Figure 1}{Figure 2}

Surgical technique

The rats were operated under general anesthesia with intraperitoneal injection of xylazine 7 mg/kg and ketamine 70 mg/kg. Operation site was prepared by shaving of lateral side of hind limb and mid back area. Post shaving cetrimide solution and betadine scrub were applied to make site sterile. Rats were positioned in prone. The sciatic nerve was exposed at the dorso-caudal region. We give an incision was 0.5 cm lateral to midline, extending 3-centimeters towards the tibio-femoral joint. The incision was deepened to muscle and fascia and fascio-muscular layers were dissected bluntly in order to expose sciatic nerve. Once the sciatic nerve is isolated, further procedure depends on the group-wise predefined manipulations. In Group I, nothing further was done and surgical wound was closed. In Group II, sciatic nerve transection was performed at two sites 1-centimeters apart. The cut segment was reversed and re-sutured by epineural microsutures using 10-0 nylon. The sutured segment was supplemented by fibrin glue. In Group, III the nerve segment was discarded and a silicone conduit (made from autoclaved silicone sheet) was used as interposition graft, with two remaining ends of nerve being inserted inside the conduit and thereafter fibrin glue was applied for approximately 30-seconds [Figure 3]. In all the rats, the wound was closed in single layer using silk 2-0. The skin was painted with povidone iodine antiseptic solution. The rats were kept in recovery chambers till complete anesthetic reversal and finally shifted to their home cages over soft bedding with free access to water and food until complete recovery. Postoperative analgesia and antibiotic were given for four days.{Figure 3}

Euthanization

Rats were euthanized at 15 weeks using carbon dioxide asphyxiation. The sutured nerve (groups II and III) and intact nerve (group I) were harvested and preserved for histopathological and electron microscopy studies, respectively.

 Results



Surgical outcome

A total of 24 rats were operated in three groups [8 rats each], and were observed for neurological, psychological for the next 15 weeks and histopathological changes (after euthanization). None of rats had surgical site infection or death.

Functional outcome

We found a poor recovery among rats of Group III and II both, and functional recovery in Group III was even poorer. Between 8th to 11th week, the rate of change in body weight remained similar in all three groups. After 11th–12th week, the rats in Group II catch-up weight to reach normal level at the end of 14th week, but rats in Group III showed a decline in growth curve [Figure 4]. The pain threshold response was better in Group II in comparison to group III but overall mechanical allodynia was present in Group II and III. A similar outcome was found for the sciatic function index.{Figure 4}

Psychological outcome

We found a unique pattern of behavioral changes among two groups, that, no outwards signs of stress were present and none of the rats showed teeth chattering and paw biting. This means rats were not considering the operated limb as 'Alien' and at-least rats were not irritated or depressed.

Toe pattern study (Out-field analysis)

We observed an interesting pattern of toe-print among rats of Group II and III. The toe print of operated limb in group II resembles a contracture posture, with fingermarks more prominent than center (we call it 'hollow paw sign') and there was a decrease stance stage, and limb dragging in a circumferential manner [Figure 5]. Contrarily, in the group III, the paw was a little outwardly placed, with medial finger marks more prominent than lateral fingermarks. The electrophysiological study would have added more insight but still, gross inference can be obtained that the regeneration in conduit group (group II) was complete, while that in group III was selective.{Figure 5}

Histopathological pattern

Histological results showed that after three months there was incomplete axonal regeneration in groups II and III [Figure 6]. The axonal regeneration in group III was less than that in group II with a mild degree of fibrosis.{Figure 6}

 Discussion



The estimated incidence of traumatic peripheral nerve injury is nearly one million per year worldwide. The peripheral nerve injury has a poor impact on patient's quality of life and economic burden.[6] The sensory and motor functional defects may result in complete paralysis of the affected limb, partial paralysis with functionally ineffective limb or neuropathic pain. Peripheral nerves have ability to regenerate, but the physiological process is often unsatisfactory or inadequate. There is an utmost need to find innovative therapies to supplement or augment the physiological process of repair. With the availability of new biomaterials and synthetic conduits materials, researchers are focusing on innovative cheaper alternatives.[1],[2]

The functional recovery or nerve regeneration depends on many factors like (a) age of the patient, (b) level of injury, (c) mechanism of injury, (d) duration from injury to repair, and (e) patient's compliance. Other physiological factors include the speed of axonal regeneration, amount of re-innervation and plasticity.[7],[8],[9] This regeneration process is often misaligned due to positional mismatch between regenerating axons and target.[10] The misalignment is prevented by using a conduit as it prevents the multi-directional growth of regenerating axons and ameliorates ill-effects of chronic flexure contracture. Therefore, we explored an economical, cost-effective conduit for interposition graft.

We used silicone sheets and made conduits in our own laboratory. For this study, we used the healthy Sprague–Dawley (SD) rats (250–300 g; 8–10 weeks) because rat nerves are comparatively larger and more resilient. The functional assessment and psychological tests is universally standardized for rat models and these tests can be performed easily. We used fibrin glue in both Groups II and III, and propose to use glue for nerve repair as reinforcement over suture anastomosis. Although the epineural suturing is the most popular method for peripheral nerve anastomosis, still the technique has inherent disadvantages of excessive handling, leading to trauma and inflammation.[11],[12] Some authors believe that the suture material, for endoneural anastomosis, may also cause hindrance in regeneration by hampering blood supply of fascicles. On the other hand, a fibrin glue is biocompatible, biodegradable, promotes angiogenesis and tissue growth and has less foreign body reactions. The fibrin glue induces less inflammation, tissue necrosis and fibrosis.[13],[14] We followed a middle path and suture nerve ends at two ends and then reinforced the anastomosis by fibrin glue. For making conduits, we used pre-autoclaved silicone sheets and roll the sheet to make silicon tube of desired size. The silicone conduits are cheap, easily available, easy to prepare tubes from silicone sheets, have no risk of viral transmission. Our results revealed that there was a decrease in the values of SFI and VHF intensity postoperatively in group III and then increased gradually but not reach to the preoperative values and this coincides with observations made by Haapaniemi et al. and Suri et al.[15],[16] However, it was observed that the axonal regeneration was more better in group III when compared with group II and also, group II showed more deposition of collagen fibers. There was no correlation between the morphological findings and the functional outcomes between group II and group III. Similar results has been shown in other studies.[17],[18],[19] Meng et al. used human amniotic membrane, as a conduit, wrapped over 10-mL transected defect but did not found any significant results.[20] We also transected same length of nerve and found similar results. We believe that the transected nerve segment, especially in rat model, should have been smaller (5–8 mL). The poor recovery pattern in Group III may be explained by (a) dissected length was more in proportionate to size of animal, (b) period of observation was less, (c) sample size was less, and (d) a possibility of technical failure. Herein, we want to highlight an interesting post-euthanization morphological finding, that majority of nerves among Group III showed good recovery [Figure 7]. It was encouraging to see morphologically aligned regenerating nerve, and a longer follow-up may provide better results. Similarly, other authors have found that subjects showed a less cold intolerance, in a median nerve injury models, using silicone conduits.[21] The digital nerves repaired by similar biodegradable polyglycolic acid tubes show good sensory recovery.[22] Other studies show less aberrant motor regeneration and good functional recovery after conduit repait.[23],[24],[25] A similar silicone conduit was described by Liang et al. and Merolli et al.[26],[27] None of our rats in group II or III showed any signs of stress and the surgical wound was satisfactory in all of them These facts, indirectly suggests that rats were in healing stage and they could still sense their hind limb (even when not responding to sensory tests). Rats with complete sensory and motor weakness usually show autophagy or at least surgical-site bite-marks. The proportional weight gain in all three groups, further adds to our inference.{Figure 7}

'Flexion contracture' or a 'unique pattern' suggesting recovery

The toe print of operated limb in group II resemble a contracture posture, with fingermarks more prominent than center (we call it 'hollow paw sign') and there was decrease stance stage, and limb dragging in a circumferential manner. Contrarily, in Group III, the paw was little outwardly placed, with medial finger marks more prominent than lateral fingermarks. The electrophysiological study would have added more insight but still gross inference can be obtained that the regeneration in conduit group (group II) was complete, while that in group III was selective.

Lack of autotomy of their fingers as a psychological sign of 'stress-relieved' or 'recovering sensory afferents'

There was no sign of infection or inflammatory reaction at the surgical site in any of the rats included. We found a unique pattern of behavioral changes among two groups, that, no outwards signs of stress were present and none of the rats showed paw biting or teeth chattering.[28] This means rats were not considering the operated limb as 'Alien' and at least rats were not irritated or depressed.

Translation of rat nerve research from desk to table

Although the rat model is most popular in 'PubMed' search for peripheral repair, some authors believe that the translation is notoriously unreliable. In Group II, we could have used suture alone or glue alone.[29] The ramp-loaded test showed inferiority of 'glue alone' with presence of more inflammation, slow absorption, and toxicity.[30] However, the issue remained under-discussed is that whether rat-nerve injury model is ideal and really translated to human periphery nerve injury surgery. It is believed that a transection of short gap may take 1–2 weeks to heal, and do better with empty conduits, compared to those conduits filled with fillers (due to viscosity of filler substance); whereas long gap takes nearly 6-weeks to heal, and may do better with a filler (axon regenerate better in Schwann cell-friendly atmosphere).[29],[30]

A 'critical nerve gap' is defined as a defect of size more than which functional recovery is not possible without an interposition graft. In rats, the critical nerve gap is nearly 1.5 cm, in rabbits it is 3 cm, and in pigs and humans, the critical nerve gap is 4-centimeters.[31],[32] [Table 1] shows a review of the literature of similar studies where conduits were used in rat regeneration models.[33],[34],[35],[36],[37],[38],[39],[40],[41] Majority of authors have used Wistar rats,[16],[34],[36],[37],[39] while Zhou et al. used SD rats.[40] In these studies, authors have shown promising electron microscopy and electrophysiological tests in the rats where conduits were used. The authors have used various growth factors; for example, seeded with Schwann cells, human bone marrow cells-seeded muscle-stuffing, brain-derived neurotrophic factor bone marrow stromal cells or even autologous nerve grafts inside the conduits. In our study, we did not use such growth factors and this may be a responsible factor for poor functional outcome. In the future, we have planned to conduct a study using growth factors stuffed silicone conduit in our animal laboratory. We are working on a larger-sized Rat model study and have planned to use several cost-effective materials as well. Our animal laboratory shall be upgraded with advanced armamentarium and readout methods such as ACTI-meter and nerve conduction study.{Table 1}

 Conclusion



In conclusion, this study showed that silicone conduit is an inferior alternative to autologous nerve graft, but has good functional recovery in the late stages. Although the result did not show a significant improvement in outcome, but an improving clinical trend was seen. These effects could have therapeutic importance in clinical settings and silicone conduits may be used as economical and effective alternative for short segment gap. Further studies, with larger sample size and longer follow-up, are warranted to justify our results statistically.

Acknowledgements

I want to acknowledge Mr. Satish Kumar Gautam, Assistant Technician, Animal House, Sanjay Gandhi Post Graduate Institute of Medical Sciences, Lucknow for his invaluable contribution and help in animal handling.

Financial support and sponsorship

Intramural project funding number A-01-PGI/IMP/69/2016.

Conflicts of interest

There are no conflicts of interest.

References

1Ray WZ, Mackinnon SE. Management of nerve gaps: Autografts, allografts, nerve transfers, and end-to-side neurorrhaphy. Exp Neurol 2010;223:77-85.
2de Ruiter GC, Malessy MJ, Yaszemski MJ, Windebank AJ, Spinner RJ. Designing ideal conduits for peripheral nerve repair. Neurosurg Focus 2009;26:E5.
3Muheremu A, Ao Q. Past, present, and future of nerve conduits in the treatment of peripheral nerve injury. Biomed Res Int 2015;2015:237507. doi: 10.1155/2015/237507.
4Waitayawinyu T, Parisi DM, Miller B, Luria S, Morton HJ, Chin SH, et al. A comparison of polyglycolic acid versus type 1 collagen bioabsorbable nerve conduits in a rat model: An alternative to autografting. J Hand Surg Am 2007;32:1521-9.
5Jessen KR, Mirsky R, Lloyd AC. Schwann cells: Development and role in nerve repair. Cold Spring Harb Perspect Biol 2015;7:a020487.
6Garozzo D. Peripheral nerve injuries and their surgical treatment: New perspectives on a changing scenario. Neurol India 2019;67(Suppl):S20-2.
7Kamble N, Shukla D, Bhat D. Peripheral nerve injuries: Electrophysiology for the neurosurgeon. Neurol India 2019;67:1419-22.
8Bhandari PS. Management of peripheral nerve injury. J Clin Orthop Trauma 2019;10:862-6.
9Midha R, Grochmal J. Surgery for nerve injury: Current and future perspectives. J Neurosurg 2019;130:675-85.
10Hamilton SK, Hinkle ML, Nicolini J, Rambo LN, Rexwinkle AM, Rose SJ, et al. Misdirection of regenerating axons and functional recovery following sciatic nerve injury in rats. J Comp Neurol 2011;519:21-33.
11Tountas CP, Bergman RA, Lewis TW, Stone HE, Pyrek JD, Mendenhall HV. A comparison of peripheral nerve repair using an absorbable tubulization device and conventional suture in primates. J Appl Biomater 1993;4:261-8.
12Hentz VR, Rosen JM, Xiao SJ, McGill KC, Abraham G. A comparison of suture and tubulization nerve repair techniques in a primate. J Hand Surg Am 1991;16:251-61.
13Koulaxouzidis G, Reim G, Witzel C. Fibrin glue repair leads to enhanced axonal elongation during early peripheral nerve regeneration in an in vivo mouse model. Neural Regen Res 2015;10:1166-71.
14Sameem M, Wood TJ, Bain JR. A systematic review on the use of fibrin glue for peripheral nerve repair. Plast Reconstr Surg 2011;127:2381-90.
15Haapaniemi T, Nishiura Y, Dahlin LB. Functional evaluation after rat sciatic nerve injury followed by hyperbaric oxygen treatment. J Peripher Nerv Syst 2002;7:149-54.
16Suri A, Mehta VS, Sarkar C. Microneural anastomosis with fibrin glue: An experimental study. Neurol India 2002;50:23-6.
17Weber RA, Breidenbach WC, Brown RE, Jabaley ME, Mass DP. A randomized prospective study of polyglycolic acid conduits for digital nerve reconstruction in humans. Plast Reconstr Surg 2000;106:1036–45.
18Chen YS, Hsieh CL, Tsai CC, Chen TH, Chen WC, Hu CL, et al. Peripheral nerve regeneration using silicone rubber chambers filled with collagen, laminin and fibronectin. Biomaterials 2000;21:1541-7.
19Nan J, Hu X, Li H, Zhang X, Piao R. Use of nerve conduits for peripheral nerve injury repair: A web of science-based literature analysis. Neural Regen Res 2012;7:2826-33.
20Meng H, Li M, You F, Du J, Luo Z. Assessment of processed human amniotic membrane as a protective barrier in rat model of sciatic nerve injury. Neurosci Lett 2011;496:48-53.
21Lundborg G, Rosen B, Dahlin L, Holmberg J, Rosen I. Tubular repair of the median or ulnar nerve in the human forearm: A 5-year follow-up. J Hand Surg Br 2004;29:100–7.
22Meek MF. A randomized prospective study of polyglycolic acid conduits for digital nerve reconstruction in humans. Plast Reconstr Surg 2001;108:1087-8.
23Tomita K, Kubo T, Matsuda K, Hattori R, Fujiwara T, Yano K, et al. Effect of conduit repair on aberrant motor axon growth within the nerve graft in rats. Microsurgery 2007;27:500-9.
24Jiang B, Zhang P, Jiang B. Advances in small gap sleeve bridging peripheral nerve injury. Artif Cells Blood Substit Immobil Biotechnol 2010;38:1-4.
25Zhang P, Han N, Wang T, Xue F, Kou Y, Wang Y, et al. Biodegradable conduit small gap tubulization for peripheral nerve mutilation: A substitute for traditional epineurial neurorrhaphy. Int J Med Sci 2013;10:171-5.
26Liang X, Cai H, Hao Y, Sun G, Song Y, Chen W. Sciatic nerve repair using adhesive bonding and a modified conduit. Neural Regen Res 2014;9:594-601.
27Merolli A, Rocchi L, Wang XM, Cui FZ. Peripheral nerve regeneration inside collagen-based artificial nerve guides in humans. J Appl Biomater Funct Mater 2015;13:61–5.
28Abuduhadeer T. Neuropathic pain intensity depends on the degree of peripheral nerve injury in the rat. J Nippon Med Sch 2004;71:399-407.
29Elgazzar RF, Abdulmajeed I, Mutabbakani M. Cyanoacrylate glue versus suture in peripheral nerve reanastomosis. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2007;104:465-72.
30Menovsky T, Beek JF. Laser, fibrin glue, or suture repair of peripheral nerves: A comparative functional, histological, and morphometric study in the rat sciatic nerve. J Neurosurg 2001;95:694-9.
31Kaplan HM, Mishra P, Kohn J. The overwhelming use of rat models in nerve regeneration research may compromise designs of nerve guidance conduits for humans. J Mater Sci Mater Med 2015;26:226.
32Sinis N, Schaller HE, Becker ST, Schlosshauer B, Doser M, Roesner H, et al. Long nerve gaps limit the regenerative potential of bioartificial nerve conduits filled with Schwann cells. Restor Neurol Neurosci 2007;25:131-41.
33Francel PC, Francel TJ, Mackinnon SE, Hertl C. Enhancing nerve regeneration across a silicone tube conduit by using interposed short-segment nerve grafts. J Neurosurg 1997;87:887-92.
34Biazar E, Keshel SH, Pouya M, Rad H, Nava MO, Azarbakhsh M, et al. Nanofibrous nerve conduits for repair of 30-mm-long sciatic nerve defects. Neural Regen Res 2013;8:2266-74.
35Choi J, Kim JH, Jang JW, Kim HJ, Choi SH, Kwon SW. Decellularized sciatic nerve matrix as a biodegradable conduit for peripheral nerve regeneration. Neural Regen Res 2018;13:1796-803
36Li BB, Yin YX, Yan QJ, Wang XY, Li SP. A novel bioactive nerve conduit for the repair of peripheral nerve injury. Neural Regen Res 2016;11:150-5.
37Ganga MV, Coutinho-Netto J, Colli BO, Marques Junior W, Catalão CH, Santana RT, et al. Sciatic nerve regeneration in rats by a nerve conduit engineering with a membrane derived from natural latex. Acta Cir Bras 2012;27:885-91.
38Ramli K, Gasim AI, Ahmad AA, Htwe O, Mohamed Haflah NH, Law ZK, et al. Efficacy of human cell-seeded muscle-stuffed vein conduit in rat sciatic nerve repair. Tissue Eng Part A 2019;25:1438-55.
39Sun XH, Che YQ, Tong XJ, Zhang LX, Feng Y, Xu AH, et al. Improving nerve regeneration of acellular nerve allografts seeded with SCs bridging the sciatic nerve defects of rat. Cell Mol Neurobiol 2009;29:347-53.
40Zhou LN, Zhang JW, Liu XL, Zhou LH. Co-graft of bone marrow stromal cells and schwann cells into acellular nerve scaffold for sciatic nerve regeneration in rats. J Oral Maxillofac Surg 2015;73:1651-60.
41Akbari H, Farrokhi B, Emami SA, Akhoondinasab MR, Akbari P, Karimi H. Comparison of the never repair with fibrin glue and perineural micro-suture in rat model. World J Plast Surg 2020;9:44-7.