A new nerve coaptation technique using a biodegradable honeycomb-patterned film

Effects of 7,8-dihydroxycoumarin on the myelin morphological changes and PSD-95 protein expression in Balb/c mice after sciatic nerve injury

OBJECTIVE

To investigate the effects of 7,8-dihydroxycoumarin on the myelin morphological changes and PSD-95 protein expression in mice with sciatic nerve injury, and to explore the relationship between PSD-95 protein and myelin regeneration after nerve myelin injury.

METHODS

One hundred twenty-seven male adult Balb/c mice were selected and randomly divided into high, medium and low 7,8-dihydroxycoumarin dose groups and blank control group. Anastomosis was then carried out for the amputated right sciatic nerve, and intraperitoneal injection of 7,8-dihydroxycoumarin was applied postoperatively. At weeks 1, 2, 4 and 8 after surgery, nervous tissues from the injury side were taken for immunohistochemical Luxol Fast Blue staining, so as to observe the morphological changes of the locally injured nerve myelin. Meanwhile, PSD-95 mRNA and protein expression were determined using real-time PCR and western blotting.

RESULTS

The nerve myelin recovery in injury side of mice at all time points showed a definite dose-effect relationship with the dose of 7,8-dihydroxycoumarin. Moreover, 7,8-dihydroxycoumarin could inhibit the PSD-95 mRNA level and protein expression. At the same time, there was a dose-effect of the inhibition.

CONCLUSIONS

7,8-Dihydroxycoumarin can affect nerve recovery in mice with sciatic nerve injury, which shows a definite dose-effect relationship with its dose. Besides, PSD-95 protein expression can suppress the regeneration of the injured nerve myelin.

Protective effect of biodegradable nerve conduit against peripheral nerve adhesion after neurolysis

OBJECTIVE Peripheral nerve adhesion caused by extraneural and intraneural scar formation after neurolysis leads to nerve dysfunction. The authors previously developed a novel very flexible biodegradable nerve conduit composed of poly(L-lactide) and poly(ε-caprolactone) for use in peripheral nerve regeneration. In the present study, they investigated the effect of protective nerve wrapping on preventing adhesion in a rat sciatic nerve adhesion model. METHODS Rat sciatic nerves were randomly assigned to one of the following four groups: a no-adhesion group, which involved neurolysis alone without an adhesion procedure; an adhesion group, in which the adhesion procedure was performed after neurolysis, but no treatment was subsequently administered; a nerve wrap group, in which the adhesion procedure was performed after neurolysis and protective nerve wrapping was then performed with the nerve conduit; and a hyaluronic acid (HA) group, in which the adhesion procedure was performed after neurolysis and nerve wrapping was then performed with a 1% sodium HA viscous solution. Six weeks postoperatively, the authors evaluated the extent of scar formation using adhesion scores and biomechanical and histological examinations and assessed nerve function with electrophysiological examination and gastrocnemius muscle weight measurement. RESULTS In the adhesion group, prominent scar tissue surrounded the nerve and strongly adhered to the nerve biomechanically and histologically. The motor nerve conduction velocity and gastrocnemius muscle weight were the lowest in this group. Conversely, the adhesion scores were significantly lower, motor nerve conduction velocity was significantly higher, and gastrocnemius muscle weight was significantly higher in the nerve wrap group than in the adhesion group. Additionally, the biomechanical breaking strength was significantly lower in the nerve wrap group than in the adhesion group and HA group. The morphological properties of axons in the nerve wrap group were preserved. Intraneural macrophage invasion, as assessed by the number of CD68- and CCR7-positive cells, was less severe in the nerve wrap group than in the adhesion group. CONCLUSIONS The nerve conduit prevented post-neurolysis peripheral nerves from developing adhesion and allowed them to maintain their nerve function because it effectively blocked scarring and prevented adhesion-related damage in the peripheral nerves.

Novel Anti-Adhesive CMC-PE Hydrogel Significantly Enhanced Morphological and Physiological Recovery after Surgical Decompression in an Animal Model of Entrapment Neuropathy

We developed a novel hydrogel derived from sodium carboxymethylcellulose (CMC) in which phosphatidylethanolamine (PE) was introduced into the carboxyl groups of CMC to prevent perineural adhesions. This hydrogel has previously shown excellent anti-adhesive effects even after aggressive internal neurolysis in a rat model. Here, we confirmed the effects of the hydrogel on morphological and physiological recovery after nerve decompression. We prepared a rat model of chronic sciatic nerve compression using silicone tubing. Morphological and physiological recovery was confirmed at one, two, and three months after nerve decompression by assessing motor conduction velocity (MCV), the wet weight of the tibialis anterior muscle and morphometric evaluations of nerves. Electrophysiology showed significantly quicker recovery in the CMC-PE group than in the control group (24.0 ± 3.1 vs. 21.0± 2.1 m/s (p < 0.05) at one months and MCV continued to be significantly faster thereafter. Wet muscle weight at one month significantly differed between the CMC-PE (BW) and control groups (0.148 ± 0.020 vs. 0.108 ± 0.019%BW). The mean wet muscle weight was constantly higher in the CMC-PE group than in the control group throughout the experimental period. The axon area at one month was twice as large in the CMC-PE group compared with the control group (24.1 ± 17.3 vs. 12.3 ± 9 μm²) due to the higher ratio of axons with a larger diameter. Although the trend continued throughout the experimental period, the difference decreased after two months and was not statistically significant at three months. Although anti-adhesives can reduce adhesion after nerve injury, their effects on morphological and physiological recovery after surgical decompression of chronic entrapment neuropathy have not been investigated in detail. The present study showed that the new anti-adhesive CMC-PE gel can accelerate morphological and physiological recovery of nerves after decompression surgery.

Differentiation of human amniotic epithelial cells into Schwann‑like cells via indirect co‑culture with Schwann cells in vitro

Human amniotic epithelial cells (hAECs) exhibit multi‑lineage differentiation ability. The present study investigated the possibility that hAECs possess the potential to differentiate into Schwann‑like cells using an in vitro indirect co‑culture approach. hAECs were isolated via enzymatic digestion, and immunocytochemistry and flow cytometry were performed to identify the hAECs. The hAECs were co‑cultured with Schwann cells (SCs) to differentiate the hAECs into Schwann‑like cells via induced proximity. The expression of typical S‑100 SC markers in the co‑cultured hAECs was determined via immunocytochemistry. For the functional experiments, reverse transcription quantitative polymerase chain reaction (RT‑qPCR) was performed to measure the expression levels of nerve growth factor (NGF), brain‑derived neurotrophic factor (BDNF) and glial cell‑derived neurotrophic factor (GDNF) mRNA. In addition, neurite outgrowth was measured in PC12 cells following co‑culture with the differentiated hAECs. Subsequent to co‑culture with SCs for 21 days, the hAECs exhibited spindle‑like morphology. The immunocytochemistry results revealed that the co‑cultured hAECs expressed S‑100, indicating differentiation into Schwann‑like cells. RT‑qPCR revealed that NGF, BDNF and GDNF expression was upregulated upon differentiation. The average axon length of the PC12 cells increased from 21.32±5.45 to 51.32±8.56 µm subsequent to co‑culture with the differentiated hAECs. These results demonstrate that this indirect co‑culture microenvironment induced the hAECs to differentiate into Schwann‑like cells that exhibited the morphological, phenotypic and functional characteristics of SCs. Therefore, the use of differentiated hAECs that exhibit the characteristics of SCs provides a promising alternative to the present techniques used for peripheral nerve regeneration.

Functional and electrophysiological outcome after autogenous vein wrapping of primary repaired ulnar nerves

PURPOSE

This study aimed at assessing the functional and electrophysiological recovery after vein wrapping of primary repaired ulnar nerves

METHODS

From January 2010 till December 2012, 23 patients (diagnosed with distal ulnar nerve injury) were prospectively studied where they were divided into two groups; group one (11 patients) and group two (12 patients). The injury was sharp in all cases but for one. The first group was managed by primary epineurorraphy. The second group was managed by primary epineurorraphy and autogenous vein wrapping. Final outcome was based on sensory recovery, motor recovery, and the presence or absence of electrophysiological response

RESULTS

Clinically, only one case in each group exhibited negative Tinel's sign. The second group achieved statistically significant superiority regarding motor recovery (P = 0.018), sensory recovery (P = 0.042) and electrophysiological recovery (P = 0.044). Group one showed two good, two satisfactory, six moderate, and one bad results while the second group showed five good, six satisfactory, one bad and no moderate results (P = 0.026). The first time to show clinical response in group one was the third month while in the second group it was at 1.5 month (P < 0.001). In addition, the first time to show electromyographic response in group one was at the sixth month while in group two it was at the third month

CONCLUSIONS

Vein wrapping is a simple technique that could be used reliably to augment primary neurorrhaphy particularly in cases with associated vascular or tendon injuries to prevent scarring and enhance functional and electrophysiological recovery.

Techniques and materials for enhancement of peripheral nerve regeneration: a literature review

Peripheral nerve surgery performed under unfavorable conditions results in increased scar formation and suboptimal clinical outcomes. Providing the operated nerve with a protective barrier, reduces fibrosis and adhesion formation and may lead to improved outcomes. The ideal coverage material should prevent scar and adhesion formation, and maintain nerve gliding during motion. Nerve protection using autologous tissues has shown good results, but shortcomings include donor site morbidity and limited availability. Various types of methods and materials have been used to protect nerves. There are both advantages and disadvantages associated with the various materials and techniques. In this report we summarize currently used protective materials applied for nerve coverage under various surgical conditions.