Histologic and Functional Outcomes of Conduit Wrapping for Peripheral Nerve Repair: Early Results in a Rat Model

Tensile Strength of Nerve Bridging Models Using Collagen Nerve Conduits

BACKGROUND

 In the treatment of peripheral nerve injuries with nerve defects, second-generation collagen-based conduits, such as Renerve® (Nipro, Osaka, Japan), have shown the potential for promoting nerve regeneration. However, there is concern related to the weak material properties. No previous studies have addressed the strength of the bridging model using collagen conduits. This study aimed to investigate the tensile strength and failure patterns in nerve defect models bridged with Renerve® conduits through biomechanical research.

METHODS

 Using fresh chicken sciatic nerves, we examined the maximum failure load of four groups: bridging models using Renerve® with one suture (group A), with two sutures (group B), with three sutures (group C), and end-to-end neurorrhaphy models with two sutures (group N). Each group had eight specimens. We also evaluated failure patterns of the specimens.

RESULTS

 Group N showed a significantly higher maximum failure load (0.96 ± 0.13 N) compared to groups A (0.23 ± 0.06 N, p < 0.0001), B (0.29 ± 0.05 N, p < 0.0001), and C (0.40 ± 0.10 N, p < 0.0001). Regarding failure patterns, all specimens in group A showed nerve-end dislocation from the conduit. Two specimens in group B and three specimens in group C failed due to circumferential cracks in the conduit. Six specimens in group B and five specimens in group C exhibited cutting out of sutures from the conduit.

CONCLUSION

 This study suggests that the number of sutures in synthetic collagen nerve conduits has little effect on the maximum failure load. To take advantage of its biomaterial benefits, a period of postoperative range of motion restriction may be required.

Full spectrum cannabis oil combined with omega-3 fish oil for neuropathic pain management: a novel therapeutic approach

OBJECTIVES

Current pharmacological treatments for neuropathic pain have limited efficacy and may cause undesirable side effects. Cannabidiol (CBD)-enriched cannabis oil and omega-3 fatty acids (ω-3) have emerged as potential therapeutic options due to their analgesic and anti-inflammatory properties. This study aimed to assess the antinociceptive effects of combining CBD-enriched cannabis oil and ω-3 in rat models of acute and neuropathic pain.

METHODS

Using the hot plate test for acute pain and the chronic constriction injury (CCI) model for neuropathic pain, thermal and mechanical hypersensitivity were evaluated. Additionally, walking track analysis and the rotarod test assessed functional recovery of the sciatic nerve. Beyond that, the histological analysis of sciatic nerves exposed the neuropathological findings of the treatments.

KEY FINDINGS

The combined treatment of CBD-enriched cannabis oil and ω-3 effectively prevented thermal and mechanical hypersensitivity, while also improving motor impairment-induced peripheral neuropathy. Finally, combination treatment showed a protective effect against degeneration resulting from CCI.

CONCLUSIONS

These findings underscore the potential of CBD-enriched cannabis oil and ω-3 as a novel therapeutic approach for neuropathic pain management, offering promising implications for future research and clinical practice.

Nerve Coaptation in 2023: Adjuncts to Nerve Repair Beyond Suture

Effective nerve coaptation entails tensionless repair of healthy fascicles with intact fascicular architecture and a well-vascularized environment, supportive of the regenerative cellular behaviors of neurons, immune cells, and Schwann cells. Suture coaptations have historically been used to ensure that these criteria are met for end-to-end repair, nerve transfers, and allograft or autograft reconstructions; however, unfortunately, overall restoration of function remains poor. As optimal coaptation is required for return of sensorimotor function, adjunct biomaterials are increasingly being enlisted attempting to optimize these suture-based coaptations. The purpose of this review was to discuss the biological, preclinical, and clinical data for the use of fibrin glue and nerve wraps made of type 1 collagen, porcine small intestine submucosa, chitosan, and human amniotic membrane. This study provides available data on each material's ability to optimize the regenerative potential of nerve repair as well as available outcomes data. Although each biomaterial discussed has benefits to nerve regeneration, at large, data remain heterogeneous, and continued investigation is required to fully understand the specific mechanisms involved and the long-term potential clinical impacts each can provide for improvement of sensorimotor outcomes.

Safety and efficacy of an injectable nerve-specific hydrogel in a rodent crush injury model

INTRODUCTION/AIMS

While the peripheral nervous system has the inherent ability to recover following injury, results are often unsatisfactory, resulting in permanent functional deficits and disability. Therefore, methods that enhance regeneration are of significant interest. The present study investigates an injectable nerve-tissue-specific hydrogel as a biomaterial for nerve regeneration in a rat nerve crush model.

METHODS

Nerve-specific hydrogels were injected into the subepineurial space in both uninjured and crushed sciatic nerves of rats to assess safety and efficacy, respectively. The animals were followed longitudinally for 12 wk using sciatic functional index and kinematic measures. At 12 wk, electrophysiologic examination was also performed, followed by nerve and muscle histologic assessment.

RESULTS

When the hydrogel was injected into an uninjured nerve, no differences in sciatic functional index, kinematic function, or axon counts were observed. A slight reduction in muscle fiber diameter was observed in the hydrogel-injected animals, but overall muscle area and kinematic function were not affected. Hydrogel injection following nerve crush injury resulted in multiple modest improvements in sciatic functional index and kinematic function with an earlier return to normal function observed in the hydrogel treated animals as compared to untreated controls. While no improvements in supramaximal compound motor action potential were observed in hydrogel treated animals, increased axon counts were observed on histologic assessment.

DISCUSSION

These improvements in functional and histologic outcomes in a rapidly and fully recovering model suggest that injection of a nerve-specific hydrogel is safe and has the potential to improve outcomes following nerve injury.