The effects of 4-aminopyridine and methylprednisolone on recovery of the facial nerve crush injury

Efficacy and mechanisms of concentrated growth factor on facial nerve rehabilitation in a rabbit model

Accelerated rehabilitation following facial nerve injury presents unique clinical challenges. This study evaluates the therapeutic effects of concentrated growth factor (CGF) on facial nerve recovery in a rabbit model and on RSC96 Schwann cells. Characterization of the CGF membrane (CGFM) revealed a three-dimensional fibrin network with embedded platelets, and representative growth factors, including TGF-β1, PDGF-BB, IGF-1, bFGF, and VEGF, were detected. In vivo, the Crush + CGFM group exhibited enhanced axon and myelin regeneration, increased Schwann cell proliferation, and improved facial nerve function compared to the Crush group. In vitro, CGF treatment significantly promoted the proliferation and migration of RSC96 cells and facilitated axon elongation in NG108-15 cells compared to controls. Mechanistically, CGF treatment led to a significant increase in PDGFRβ phosphorylation. Inhibition of this pathway with SU16f decreased Schwann cell activity and hindered overall nerve rehabilitation. These results underscore CGF's potential to accelerate nerve repair by promoting axon and myelin regeneration and enhancing Schwann cell biological activity, with the PDGFRβ pathway playing a crucial regulatory role. This study highlights CGF as a promising therapeutic strategy for improving facial nerve rehabilitation.

The effect of caffeic acid phenethyl ester on facial nerve regeneration

BACKGROUND

Caffeic acid phenethyl ester (CAPE), an active component of honey bee propolis, has been demonstrated in animal models and studies to have anti-inflammatory, antioxidant, immunomodulatory, neuroprotective, and cytoprotective properties.

OBJECTIVE

We investigated the efficacy of CAPE, which we believe may be therapeutically useful in facial nerve restoration due to its neuroprotective and antioxidant properties.

MATERIAL AND METHODS

20 Sprague Dawley rats were divided randomly into 4 primary and 2 secondary groups and assigned as control, methylprednisolone, CAPE, CAPE+methylprednisolone groups and the sham and the trauma groups. Except for the sham group, all groups had the left facial nerve crushed. Three weeks after surgery, prospective functional, electrophysiologic, and histologic recovery was assessed.

RESULTS

The CAPE and CAPE+methylprednisolone group had similar and more significant recovery at Nerve Excitability Thresholds and achieved a significantly faster improvement in histopathological evaluation at the end of three weeks.

CONCLUSIONS AND SIGNIFICANCE

The combination of CAPE and methylprednisolone was found to be efficient in nerve regeneration in an experimental rat facial nerve crush model. Given the strong systemic adverse effects of methylprednisolone, the combination of CAPE may be a good alternative for lowering the dose of methylprednisolone and thereby reducing its negative effects.

The potential role of SCF combined with DPCs in facial nerve repair

Facial nerve injuries lead to significant functional impairments and psychological distress for affected patients. Effective repair of these injuries remains a challenge. For longer nerve gaps, the regeneration outcomes after nerve grafting remain suboptimal due to limited sources and postoperative immune responses. Tissue engineering techniques are conventional methods for repairing peripheral nerve defects. This study explores the potential of dental pulp cells (DPCs) combined with stem cell factor (SCF) to enhance neurogenic differentiation and improve facial nerve regeneration. DPCs were isolated from rabbit dental pulp, the pluripotency of the cells was identified from three perspectives: osteogenic differentiation, adipogenic differentiation, and neurogenic differentiation. In vivo experiments involved injuring the buccal branch of the facial nerve in New Zealand white rabbits, followed by treatment with PBS, DPCs, SCF, or SCF + DPCs. Functional recovery was assessed over 12 weeks, with SCF + DPCs demonstrating the most significant improvement in whisker movement scores. Histomorphological evaluations revealed enhanced myelinated fiber density and axonal morphology in the SCF + DPCs group. RNA sequencing identified 608 differentially expressed genes, with enrichment in the TGF-β signaling pathway. In in vitro experiments, we demonstrated from multiple angles using Western blot analysis, Real-time quantitative polymerase chain reaction (QPCR) analysis, and immunofluorescence staining that SCF can promote the neurogenic differentiation of DPCs through the TGF-β1 signaling pathway. Our findings indicate that the combination of SCF and DPCs offers a promising strategy for enhancing facial nerve repair.

Facial nerve regeneration via body-brain crosstalk: The role of stem cells and biomaterials

The human body is a complex, integral whole, and disruptions in one organ can lead to dysfunctions in other parts of the organ network. The facial nerve, as the seventh cranial nerve, arises from the brainstem, controls facial expression muscles and plays a crucial role in brain-body communication. This vulnerable nerve can be damaged by trauma, inflammation, tumors, and congenital diseases, often impairing facial expression. Stem cells have gained significant attention for repairing peripheral nerve injuries due to their multidirectional differentiation potential. Additionally, various biomaterials have been used in tissue engineering for regeneration and repair. However, the therapeutic potential of stem cells and biomaterials in treating facial nerve injuries requires further exploration. In this review, we summarize the roles of stem cells and biomaterials in the regeneration and repair of damaged facial nerves, providing a theoretical basis for the recovery and reconstruction of body-brain crosstalk between the brain and facial expression muscles.

Protective vs. Therapeutic Effects of Mitochondria-Targeted Antioxidant MitoTEMPO on Rat Sciatic Nerve Crush Injury: A Comprehensive Electrophysiological Analysis

Protective vs. Therapeutic Effects of Mitochondria-Targeted Antioxidant MitoTEMPO on Rat Sciatic Nerve Crush Injury: A Comprehensive Electrophysiological Analysis. Peripheral nerve injuries often result in long-lasting functional deficits, prompting the need for effective interventions. MitoTEMPO (2-(2,2,6,6-tetramethylpiperidin-1-oxyl-4-ylamino)-2-oxoethyl) triphenylphosphonium chloride) is a mitochondria-targeted antioxidant that has shown protective and therapeutic effects against pathologies associated with reactive oxygen species. This study explores the utilization of MitoTEMPO as a therapeutic and protective agent for sciatic nerve crush injuries. By employing advanced mathematical approaches, the study seeks to comprehensively analyze nerve conduction parameters, nerve excitability, and the distribution of nerve conduction velocities to gauge the potential. Forty Wistar-Albino rats were randomly divided into following groups: (I) SHAM-animals subjected to sham operation and treated intraperitoneally (i.p.) with vehicle (bidistilled water) for 14 days; (II) CI (crush injury)-animals subjected to CI and treated with vehicle 14 days; (III) MiP-animals subjected to 7 days i.p. MitoTEMPO treatment before CI (0.7 mg/kg/day dissolved in vehicle) and, only vehicle for 7 days after CI, protective MitoTEMPO; and (IV) MiT-animals i.p. treated with only vehicle for 7 days before CI and 7 days with MitoTEMPO (0.7 mg/kg/day dissolved in vehicle) after CI, therapeutic MitoTEMPO. Nerve excitability parameters were measured, including rheobase and chronaxie, along with compound action potential (CAP) recordings. Advanced mathematical analyses were applied to CAP recordings to determine nerve conduction velocities and distribution patterns. The study revealed significant differences in nerve excitability parameters between groups. Nerve conduction velocity was notably reduced in the MiP and CI groups, whereas CAP area values were diminished in the MiP and CI groups compared to the MiT group. Furthermore, CAP velocity was lower in the MiP and CI groups, and maximum depolarization values were markedly lower in the MiP and CI groups compared to the SHAM group. The distribution of nerve conduction velocities indicated alterations in the composition of nerve fiber groups following crush injuries. In conclusion, postoperative MitoTEMPO administration demonstrated promising results in mitigating the detrimental effects of nerve crush injuries.

Establishment of a facial nerve trunk crush injury model and evaluation of facial nerve self-healing in rats

INTRODUCTION/AIMS

To facilitate further investigation into the mechanisms of facial nerve regeneration, a simple and reliable model of facial nerve crush injury is essential. Nevertheless, the establishment of such models lacks standardization and repeatability, while the healing capacity of the nerve is often overlooked, potentially affecting future studies.

METHODS

We made facial nerve trunk crush injury models with different pressing times and detected the changes from the distal nerves to the motoneurons via behavior analysis, electrophysiological test, and histomorphometry analysis.

RESULTS

It revealed a particular capacity for self-healing following facial nerve crush damage because there was almost no facial motoneuron apoptosis in the MC group during the observation period, and rats in MC group had total facial paralysis in behavioral tests following surgery and varying degrees of recovery 28 days postoperatively with no treatments. As the pressing time increased, the latency, wave amplitude, nerve fiber damage degree, nerve axon ratio, myelin thickness, electroneurograph (ENoG) value, ultrastructural damage, abnormal morphological changes, and the buccal muscle atrophy of each MC group gradually increased or got worse during the observation period. However, after 28 postoperative days, only the ENoG values of the M10min and M12min groups were beyond 90%, indicating no self-healing.

DISCUSSION

It suggests that a stable model of peripheral facial palsy may be created by applying a 12.5 cm mosquito clamped to the facial nerve trunk for at least 10 min, which laid the foundation for the subsequent research to objectively evaluate facial nerve regeneration.

Effects of 4-Aminopyridine on Combined Nerve and Muscle Injury and Bone Loss

PURPOSE

Musculoskeletal injuries are common, and peripheral nerve injury (PNI) causes significant muscle and bone loss within weeks. After PNI, 4-aminopyridine (4-AP) improves functional recovery and muscle atrophy. However, it is unknown whether 4-AP has any effect on isolated traumatic muscle injury and PNI-induced bone loss.

METHODS

A standardized crush injury was performed on the sciatic nerve and muscles in mice, and the mice were assigned to receive normal saline or 4-AP treatment daily for 21 days. The postinjury motor and sensory function recovery was assessed, injured muscles were processed for histomorphometry, and the tibial bone was scanned for bone density.

RESULTS

4-Aminopyridine significantly accelerated the postinjury motor and sensory function recovery, improved muscle histomorphometry, increased muscle satellite cell numbers, and shifted muscle fiber types after combined nerve and muscle injury. Importantly, the 4-AP treatment significantly reduced PNI-induced bone loss. In contrast, in the case of isolated muscle injury, 4-AP had no effect on functional recovery and bone density, but it improved muscle-specific histomorphometry to a limited extent.

CONCLUSIONS

These findings demonstrate the potential beneficial effects of 4-AP on the recovery of muscle morphology and bone density after combined muscle and nerve injury.

CLINICAL RELEVANCE

Nerve injuries frequently involve muscle and result in rapid muscle and bone atrophy. In this scenario, 4-AP, in addition to accelerating nerve functional recovery, might work as an adjunctive agent to improve the recovery of injured muscle and attenuate PNI-induced bone loss.