Sutures or fibrin glue for divided rat nerves: Schwann cell and muscle metabolism

Nerve Regeneration after a Nerve Graft in a Rat Model: The Effectiveness of Fibrin Glue

BACKGROUND

Simulating the post-traumatic continuity defect of small human peripheral nerves, we compared the effectiveness of fibrin glue with neurorrhaphy for nerve gap restoration.

METHODS

In twenty-four male Wistar rats, a fifteen mm defect in one sciatic nerve only was made and immediately repaired with an inverted polarity autograft. According to the used technique, rats were divided into Group A (Control), using traditional neurorrhaphy, and Group B (Study), using fibrine glue sealing; in total, 50% of rats were sacrificed at 16 weeks and 50% at 21 weeks. Before sacrifice, an assessment of motor function was done through Walking Track Analysis and an electroneurophysiological evaluation. After sacrifice, selected muscle mass indexes and the histology of the regenerated nerves were assessed. All data were evaluated by Student's t test for unpaired data.

RESULTS

No significant differences were found between the two groups, with only the exception of a relative improvement in the tibialis anterior muscle's number of motor units in the study group.

CONCLUSION

Despite the fact that the use of fibrin glue as a nerve sealant is not superior in terms of functional recovery, its effectiveness is comparable to that of microsurgical repair. Hence, the faster and technically easier glueing technique could deserve broader clinical application.

Autologous Fibrin Glue Versus Microsuture in the Surgical Reconstruction of Peripheral Nerves: A Randomized Clinical Trial

PURPOSE

This study compared the motor and sensory recovery and the operative time of autologous fibrin glue application with conventional microsuturing technique in repairing peripheral nerves at the forearm and wrist levels METHODS: Eighty-five patients with injuries of the median, ulnar, or both nerves at the wrist and forearm levels underwent nerve repair between September 2014 and June 2018. Patients were randomly assigned at the time of diagnosis to a microsuture group (42 patients), in which standard epineurial microsurgical suturing was performed, or a fibrin glue group (43 patients), in which nerve repair was performed using autologous fibrin glue. The primary outcome measure was motor and sensory recovery. Operative time was the secondary outcome measure. Other outcome measures that were added post hoc, after trial initiation, included time to motor and sensory recovery; grip strength; pinch strength; Michigan hand outcome score; amplitude, latency, and duration of the compound motor unit action potential; and complications. All patients were followed up a minimum of 1 year.

RESULTS

At the final follow-up, both groups had regained similar motor and sensory function. The mean operative time was shorter in the fibrin glue group. Both groups had similar amplitude, latency, and duration of the compound motor unit action potential. Michigan Hand Outcome scores and mean percent recovery of grip strength and pinch strength were also similar. Six of 43 patients in the fibrin glue group compared with 8 of 42 patients in the microsuture group developed postoperative complications.

CONCLUSIONS

The use of fibrin glue to repair peripheral nerves is as effective as microsuturing in regaining motor and sensory functions and is associated with shorter operative time.

TYPE OF STUDY/LEVEL OF EVIDENCE

Therapeutic II.

Dose-effect relationship and molecular mechanism by which BMSC-derived exosomes promote peripheral nerve regeneration after crush injury

Background

The development of new treatment strategies to improve peripheral nerve repair after injury, especially those that accelerate axonal nerve regeneration, is very important. The aim of this study is to elucidate the molecular mechanisms of how bone marrow stromal cell (BMSC)-derived exosomes (EXOs) participate in peripheral nerve regeneration and whether the regenerative effect of EXOs is correlated with dose.

Method

BMSCs were transfected with or without an siRNA targeting Ago2 (SiAgo2). EXOs extracted from the BMSCs were administered to dorsal root ganglion (DRG) neurons in vitro. After 48 h of culture, the neurite length was measured. Moreover, EXOs at four different doses were injected into the gastrocnemius muscles of rats with sciatic nerve crush injury. The sciatic nerve functional index (SFI) and latency of thermal pain (LTP) of the hind leg sciatic nerve were measured before the operation and at 7, 14, 21, and 28 days after the operation. Then, the number and diameter of the regenerated fibers in the injured distal sciatic nerve were quantified. Seven genes associated with nerve regeneration were investigated by qRT-PCR in DRG neurons extracted from rats 7 days after the sciatic nerve crush.

Results

We showed that after 48 h of culture, the mean number of neurites and the length of cultured DRG neurons in the SiAgo2-BMSC-EXO and SiAgo2-BMSC groups were smaller than that in the untreated and siRNA control groups. The average number and diameter of regenerated axons, LTP, and SFI in the group with 0.9 × 10¹⁰ particles/ml EXOs were better than those in other groups, while the group that received a minimum EXO dose (0.4 × 10¹⁰ particles/ml) was not significantly different from the PBS group. The expression of PMP22, VEGFA, NGFr, and S100b in DRGs from the EXO-treated group was significantly higher than that in the PBS control group. No significant difference was observed in the expression of HGF and Akt1 among the groups.

Conclusions

These results showed that BMSC-derived EXOs can promote the regeneration of peripheral nerves and that the mechanism may involve miRNA-mediated regulation of regeneration-related genes, such as VEGFA. Finally, a dose-effect relationship between EXO treatment and nerve regeneration was shown.

Multiple uses of fibrin sealant for nervous system treatment following injury and disease

Lesions to the nervous system often produce hemorrhage and tissue loss that are difficult, if not impossible, to repair. Therefore, scar formation, inflammation and cavitation take place, expanding the lesion epicenter. This significantly worsens the patient conditions and impairment, increasing neuronal loss and glial reaction, which in turn further decreases the chances of a positive outcome. The possibility of using hemostatic substances that also function as a scaffold, such as the fibrin sealant, reduces surgical time and improve postoperative recovery. To date, several studies have demonstrated that human blood derived fibrin sealant produces positive effects in different interventions, becoming an efficient alternative to suturing. To provide an alternative to homologous fibrin sealants, the Center for the Study of Venoms and Venomous Animals (CEVAP, Brazil) has proposed a new bioproduct composed of certified animal components, including a thrombin-like enzyme obtained from snake venom and bubaline fibrinogen. Thus, the present review brings up to date literature assessment on the use of fibrin sealant for nervous system repair and positions the new heterologous bioproduct from CEVAP as an alternative to the commercial counterparts. In this way, clinical and pre-clinical data are discussed in different topics, ranging from central nervous system to peripheral nervous system applications, specifying positive results as well as future enhancements that are necessary for improving the use of fibrin sealant therapy.

Nerve glue for upper extremity reconstruction

Nerve glue is an attractive alternative to sutures to improve the results of nerve repair. Improved axon alignment, reduced scar and inflammation, greater and faster reinnervation, and better functional results have been reported with the use of nerve glue. The different types of nerve glue and the evidence to support or oppose their use are reviewed. Although the ideal nerve glue has yet to be developed, fibrin sealants can be used as nerve glue in select clinical situations. Technology to allow suture-free nerve repair is one development that can potentially improve functional nerve recovery and the outcomes of upper extremity reconstruction.

Anal sphincter reconstruction using a transposed gracilis muscle with a pudendal nerve anastomosis: a preliminary anatomic study

PURPOSE

Few studies have demonstrated the feasibility of cross innervating a skeletal muscle neosphincter with the pudendal nerve in an animal model. This study was designed to evaluate in humans the technical feasibility of anastomosing the nerve of the gracilis muscle and the pudendal nerve when the gracilis muscle is transposed around the anus.

METHODS

Anatomic assessment was made in 30 cases. The gracilis muscle and its principal neurovascular pedicle were dissected and the nerve to the gracilis divided at its origin. The gracilis muscle, accompanied by its nerve, was then transposed around the anus. The pudendal nerve was dissected in its extrapelvic portion and divided at its termination. Gracilis reinnervation was considered feasible when the proximal end of the nerve to the gracilis muscle and the distal end of the pudendal nerve were able to be placed into tension-free contact.

RESULTS

The mean lengths of the nerve to the gracilis and the pudendal nerve were 126.5 +/- 20.6 mm and 57.5 +/- 16.3 mm. Anastomosing the nerve of the gracilis muscle and the pudendal nerve was possible in 28 cases. There was a total mean surplus nerve length of 25.1 +/- 20.9 mm. In 26 cases, the distal end of the pudendal nerve (mean, 3.3 +/- 1.1 mm) was similar or larger than the end of the nerve to the gracilis (mean, 3 +/- 0.8 mm).

CONCLUSIONS

Anal sphincter reconstruction using transposed gracilis muscle with pudendal nerve anastomosis is anatomically achievable in cadavers, and supports the potential applications of this technique for perineal reconstruction in clinical practice.

Overall assessment of regeneration in peripheral nerve lesion repair using fibrin glue, suture, or a combination of the 2 techniques in a rat model. Which is the ideal choice?

BACKGROUND

Nerve repair with fibrin glue is an alternative to conventional suture technique, although there is no definitive experimental evaluation of the 2 techniques. This experimental study was undertaken to evaluate nerve regeneration after sciatic nerve repair with fibrin glue and to compare it with repair performed with suture and a combination of both techniques.

METHODS

Eighty-six male Wistar rats were subjected to right sciatic nerve transection and immediate repair with 4-stitch nylon suture (group A), fibrin glue (group B), or a combination of both techniques (group C). Walking track analysis to access functional recovery was performed preoperatively and 12 weeks postoperatively. Before nerve section and after a 24-week interval, the nerve and motor action potentials (MAPs) were evaluated. Histomorphometric evaluation was carried out 24 weeks after nerve section. Differences between groups were evaluated for significance using the Kruskal-Wallis or analysis of variance methods.

RESULTS

Animals of group B presented better results than those of group A when the functional evaluation was applied (P < .05). When nerve conduction velocity was evaluated at reoperation and the ratio between conduction velocity at reoperation and before the nerve section in MAP evaluation were measured and compared in the 3 groups, the rats of group B presented better results than those of group A (P < .05). Animals of group C presented better results than those of group A when the ratio between nerve conduction velocities was considered. There was no difference between the nerve repair methods when histomorphometric evaluation was performed.

CONCLUSION

In a rat model, nerve repair using fibrin glue provided better conditions for regeneration than suture after sciatic nerve transection.

[Reconstruction of the anus by the gracilis muscle reinnervated by the pudendal nerve. A preliminary anatomical study]

The aim of this study is to evaluate the possibilities of reinnervation of the gracilis muscle, transposed around the anus, by the pudendal nerve with an end-to-side nerve anastomosis.

METHODS

This study was carried out in 10 cases. The gracilis muscle and its vascular-nervous pedicle have been dissected. The nerve of the gracilis muscle has been cut at its origin. The gracilis muscle was transposed around the anus. The nerve of the gracilis muscle was transposed in the gluteal area. The pudendal nerve has been dissected from its extra-pelvic part. The reinnervation with an end-to-side nerve anastomosis has been considered as feasible when the proximal ending of the nerve of the gracilis was put into a tension free contact with the extra-pelvic part of the pudendal nerve.

RESULTS

The reinnervation of the gracilis muscle by the pudendal nerve has been possible in all cases. The extra-pelvic part of the pudendal nerve has a common trunk in 8 cases. The width of the extra-pelvic part of the pudendal nerve was 2.8 +/- 0.8 mm (1-3.5). The width of the proximal endings of the nerve innervating the gracilis muscle was 2.5 +/- 0.5 mm (2-3). After transposition of the nerve of the gracilis muscle in the gluteal area an average supplementary length of 20.9 +/- 16.8 mm was available (range 5-52).

CONCLUSIONS

These results suggest that a reconstruction of the anal sphincter with a gracilis muscle transposed around the anus and reinnervated by the pudendal nerve with end-to-side nerve anastomosis is possible.

Primary sciatic nerve repair using titanium staples

The primary epineural repair of human peripheral nerves is most often achieved using non-absorbable microsutures, which can elicit a foreign-body reaction. We describe a new system for neural-tissue approximation, consisting of non-penetrating vascular closure staples (VCS) applied to the epineurium. These clips were initially developed for use in microvascular anastomosis, with no knowledge of their effectiveness in neural-tissue approximation. We compare the efficacies of VCS clips and monofilament nylon microsutures in the repair of transected sciatic nerves in 36 adult Sprague Dawley rats (18 treated with 9/0 sutures and 18 treated with VCS clips). In the rat, regeneration starts by day 5, and is well advanced by 4 weeks. To assess the overall repair success, the site of injury, after perfusion fixation, was harvested at 5, 7 and 30 days. The two methods were compared in terms of operative time, the degree of self-mutilation (autotomy), the macroscopic specimens in vivo and the microanatomical continuity through the repair site. Continuity was studied by using PGP-9.5-labelled cryosections and fluorescent secondary antibodies to visualise axonal regeneration. Clip repair was significantly faster in the VCS group (mean +/- s.e.m. = 7.09 +/- 0.36 min versus mean +/- s.e.m. 11.56 +/- 0.51 min in the sutured group) and an equal and minimal degree of autotomy was observed. Macroscopically, all 36 nerves were in continuity and free from neuroma. The use of VCS clips resulted in equivalent visualised regeneration across the repair site at each time point. We believe the use of VCS clips to be a faster and comparable alternative to non-absorbable sutures in primary nerve repair in this experimental model.

Functional perineal colostomy with pudendal nerve anastomosis following anorectal resection: a cadaver operation study on a new procedure

BACKGROUND

We have previously studied functional perineal colostomy that used skeletal muscle with pudendal nerve anastomosis (PNA) following anorectal resection in an animal model. In that study the neosphincter reconstructed with PNA achieved the proper functions of the external anal sphincter resulting in a satisfactory defecatory condition. This study was a preliminary step before applying this procedure to human beings.

METHODS

We reconstructed a new anal sphincter by using the lower part of the gluteus maximus muscle (lower GMM) with PNA in a total of six sides of four human cadavers and investigated the anatomic problems associated with this procedure.

RESULTS

We classified the branching patterns of the inferior gluteal nerve into three types. The length of the branches of the inferior gluteal nerve to the lower GMM varied from 32 to 76 mm (median, 57 mm). The length of the pudendal nerve (PN) passing out below the sacrotuberous ligament varied from 21 to 44 mm (median, 29.5 mm). The PN was anastomosed to the nerve innervating the lower GMM with the redundancy of 17 to 36 mm (median, 24.5 mm). In all cases the anal sphincter reconstruction with a PNA maneuver was anatomically feasible by using the lower GMM. The length of the new anal canal was 65 to 80 mm (median, 67.5 mm).

CONCLUSIONS

The PNA maneuver was an anatomically applicable method to make a neoanus in human beings. Preparation for the application of this method to human beings was accomplished.

A comparison of glue and a tube as an anastomotic agent to repair the divided buccal branch of the rat facial nerve

The best anastomotic agent to join nerve ends is controversial. This paper describes a controlled trial between a collagen tube wrap and a tissue glue to anastomose the rat facial nerve. There was no difference in the results using photographic, histological and electrophysiological techniques.

Anastomosis of the Intratemporal Facial Nerve Using Fibrin Tissue Adhesive

This work aimed at studying the results obtained by the repair of complete lesions of the facial nerve in its intratemporal portions. Clinical, electrophysiological and surgical techniques were studied. Twenty-three patients with traumatic facial nerve lesions were operated. Nerve grafts were made in 10, and end-to-end anastomosis in thirteen. The surgical technique performed was the coaptation of the stumps and stabilization with fibrin tissue adhesive. Sixteen months after surgery, a clinical and electrophysiological evaluation was made. The use of fibrin tissue adhesive to stabilize intratemporal anastomosis of facial nerve showed clinical and electrophysiological evidence of axonal growth and reinnervation of mimical muscles of the face. These results were similar to that obtained by other authors that used other methods of microanastomosis. The use of fibrin tissue adhesive is an effective technique to utilize in intratemporal anastomosis of the facial nerve.

Increased muscle regeneration after repair of divided motor nerve with neuronotrophic factors containing glue

Neuronotrophic factors (NTFs) directed to spinal cord motor neurons were collected in rats within silicone nerve regeneration chambers according to LONGO et al. (1983b). Unilateral addition of NTFs to the fibrin glue used for the repair of divided sciatic nerves improved locally nerve regeneration without affecting the controlateral side. Nerve regeneration was assessed by weight gain of the reinnervated muscles and by radioactive labelling of the acid-soluble phosphate fractions of both nerve Schwann cells and reinnervated muscle cells. Fast gastrocnemius and slow soleus muscles, the motor nerve of which had been repaired with added NTFs, were significantly heavier (21 and 28%) than their controlateral controls, and the metabolic dedifferentiation attendant on post-division nerve repair was less marked. It is suggested that this experimental nerve regeneration model is suitable to test potential nerve-active agents in vivo, under conditions close to the usual clinical setting, with, as ultimate goal, the improvement of the end-results of microsurgical repair of peripheral nerve in man.

Fibrin seal adhesive versus nonabsorbable microsuture in peripheral nerve repair

Although nonabsorbable microsuture is the material most often used in human peripheral nerve repair, it is capable of eliciting a foreign body reaction, impairing vascularity, and potentially disrupting axonal regeneration. Sutureless methods, including fibrin seal adhesive, may offer an alternative to traditional suture techniques. This study compared the efficacy of fibrin seal with nylon microsuture in tibial microneurorrhaphy on 28 adult New Zealand white rabbits (14 with 10-0 monofilament nylon suture and 14 with fibrin seal). Each rabbit was reexplored at 1, 6, 12, and 18 weeks. The criteria used to compare the two methods were operative time, clinical function, electrophysiologic measures, and histologic findings. Fibrin seal repairs required less time to execute (p less than 0.01) but were inferior in mean conduction amplitude (p less than 0.01) and with respect to histologic criteria. Fibrin seal also appeared less effective in maintaining nerve approximation. We do not believe that fibrin seal provides a superior alternative to nonabsorbable suture in primary nerve repair in this experimental model.

[Peripheral nerve repair: value of biological glues and epiperineural suture in late interventions. Experimental study in rats]

In order to approximate as close as possible genuine clinical conditions, the sciatic nerve of the rat was divided and then repaired after a delay of one or seven days either by application of a biological glue or by an epiperineural suture technique. The metabolic activity of the sciatic nerve Schwann cells - whether located in the distal or the proximal ends - and that of the (fast acting) white gastrocnemius and (slow acting) red soleus muscle were assessed using 32P-radiolabeled acid-soluble phosphates. Delayed repair, as judged by our biochemical criteria, was equivalent whatever method, biological glue or suture, was used. The frozen and lyophilized forms of the biological glue provided similar results.