Delivery of neurotrophin-3 by RVG-Lamp2b-modified mesenchymal stem cell-derived exosomes alleviates facial nerve injury.

We aim to investigate the effect of RVG-Lamp2b-modified exosomes (exos) loaded with neurotrophin-3 (NT-3) on facial nerve injury. Exos were collected from control cells (Ctrl Exo) or bone marrow mesenchymal stem cells co-transfected with RVG-Lamp2b and NT-3 plasmids (RVG-NT-3 Exo) by gradient centrifugation and identified by western blotting, transmission electron microscopy, and nanoparticle tracking analysis. Effect of RVG-NT-3 Exo on oxidative stress damage was determined by analysis of the morphology, viability, and ROS production of neurons. Effect of RVG-NT-3 Exo on facial nerve axotomy (FNA) was determined by detecting ROS production, neuroinflammatory reaction, microglia activation, facial motor neuron (FMN) death, and myelin sheath repair. Loading NT-3 and modifying with RVG-Lamp2b did not alter the properties of the exos. Moreover, RVG-NT-3 Exo could effectively target neurons to deliver NT-3. Treatment with RVG-NT-3 Exo lowered H2O2-induced oxidative stress damage in primary neurons and Nsc-34 cells. RVG-NT-3 Exo treatment significantly decreased ROS production, neuroinflammatory response, FMN death, and elevated microglia activation and myelin sheath repair in FNA rat models. Our findings suggested that RVG-NT-3 Exo-mediated delivery of NT-3 is effective for the treatment of facial nerve injury.

Genetic association of hypertension and several other metabolic disorders with Bell's palsy.

Background: Effects of hypertension, type 2 diabetes and obesity on Bell's palsy risk remains unclear. The aim of the study was to explore whether hypertension and these metabolic disorders promoted Bell's palsy at the genetic level. Methods: Genetic variants from genome-wide association studies for hypertension, type 2 diabetes, body mass index and several lipid metabolites were adopted as instrumental variables. Two-sample Mendelian randomization including IVW and MR-Egger was used to measure the genetic relationship between the exposures and Bell's palsy. Sensitivity analyses (i.e., Cochran's Q test, MR-Egger intercept test, "leave-one-SNP-out" analysis and funnel plot) were carried out to assess heterogeneity and horizontal pleiotropy. All statistical analyses were performed using R software. Results: Hypertension was significantly associated with the increased risk of Bell's palsy (IVW: OR = 2.291, 95%CI = 1.025-5.122, p = 0.043; MR-Egger: OR = 16.445, 95%CI = 1.377-196.414, p = 0.029). Increased level of LDL cholesterol might upexpectedly decrease the risk of the disease (IVW: OR = 0.805, 95%CI = 0.649-0.998, p = 0.048; MR-Egger: OR = 0.784, 95%CI = 0.573-1.074, p = 0.132). In addition, type 2 diabetes, body mass index and other lipid metabolites were not related to the risk of Bell's palsy. No heterogeneity and horizontal pleiotropy had been found. Conclusion: Hypertension might be a risk factor for Bell's palsy at the genetic level, and LDL cholesterol might reduce the risk of the disease. These findings (especially for LDL cholesterol) need to be validated by further studies.

Mitophagy protects SH-SY5Y neuroblastoma cells against the TNFα-induced inflammatory injury: Involvement of microRNA-145 and Bnip3.

Inflammatory response is involved in the development of facial neuritis. The aim of our study is to explore the role of mitophagy in facial nerve damage induced by tumor necrosis factor α (TNFα). Our results indicated that TNFα induced SH-SY5Y cell apoptosis in a dose-dependent manner. Besides, TNFα treatment also suppressed mitophagy by reducing the expression of BCL2 interacting protein 3 (Bnip3). Overexpression of Bnip3 under sustained SH-SY5Y cell viability in the setting of TNFα-mediated inflammation injury. At the molecular levels, Bnip3 overexpression maintained mitochondrial function via preserving mitochondrial membrane potential, reducing cytochrome-c leakage and inhibiting mitochondrial permeability transition pore opening. Functional studies have suggested that microRNA-145 (miR-145) was an upstream regulator of Bnip3-dependent mitophagy. MiR-145 inhibited Bnip3 transcription and expression, leading to mitophagy inhibition. In contrast, inhibition of miR-145 reversed mitophagy activity and subsequently promoted SH-SY5Y cell survival in the context of TNFα-mediated inflammation injury. Altogether, our data identified Bnip3-dependent mitophagy as one of the defensive mechanisms to sustain mitochondrial homeostasis and SH-SY5Y cell survival. Besides, miR-145/Bnip3/mitophagy axis may be considered as a potential target for the treatment of facial neuritis in clinical practice.

Effect of chitosan combined with hyaluronate on promoting the recovery of postoperative facial nerve regeneration and function in rabbits.

To determine better solutions for postoperative nerve functional recovery, the effects of chitosan and hyaluronate on perineural scar formation and neural function recovery were investigated in 40 rabbits. Rabbits were randomized into 4 groups: A (chitosan), B (chitosan + hyaluronate), C (hyaluronate) and D (control). The rabbits underwent the same parotidectomy surgery, but different materials were used to cover the operated nerves. By evaluating specific indicators, including vibrissae motion tests, neural electrophysiological examinations and extraneural examinations, it was revealed that the amplitude of vibrissae motion of all groups had increased 6 weeks after surgery. The recovery of Group B was superior compared with all other groups at 4 and 12 weeks post-surgery; however no significant differences were detected. Group B exhibited a great number of nerve fibers, thicker myelin sheath and greater nerve conduction velocity. In summary, the use of a chitosan conduit combined with sodium hyaluronate gel may prevent perineural scar formation in facial nerves and promote nerve functional recovery.

Chitosan conduit combined with hyaluronic acid prevent sciatic nerve scar in a rat model of peripheral nerve crush injury.

In the present study, the effects of hyaluronic acid (HA) combined with chitosan conduit on peripheral nerve scarring and regeneration were investigated in a rat model of peripheral nerve crush injury. A total of 60 Sprague-Dawley rats were randomly distributed into four groups (15 rats in each group), in which the nerve was either not treated (control group) or treated with chitosan conduit, hyaluronic acid, or chitosan conduit coupled with hyaluronic acid following clamp injury to the sciatic nerve. The surgical sites were evaluated by assessing the sciatic functional index, the degree of scar adhesions, the numbers of myelinated nerve fibers, the average diameter of myelinated nerve fibers and the myelin sheath thickness. Larger epineurial scar thickness was observed in the control groups compared with the treatment groups at 4, 8 and 12 weeks following surgery. There was no significant difference in scar adhesion among the four groups at 4 weeks following surgery. However, animals receiving chitosan coupled with HA demonstrated better neural recovery, as measured by reduced nerve adherence to surrounding tissues, less scar adhesion, increased number of axons, nerve fiber diameter and myelin thickness. In conclusion, the application of chitosan conduit combined with HA, to a certain extent, inhibited sciatic nerve extraneural scaring and adhesion, and promoted neural regeneration and recovery.

Chitosan conduits combined with nerve growth factor microspheres repair facial nerve defects.

Microspheres containing nerve growth factor for sustained release were prepared by a compound method, and implanted into chitosan conduits to repair 10-mm defects on the right buccal branches of the facial nerve in rabbits. In addition, chitosan conduits combined with nerve growth factor or normal saline, as well as autologous nerve, were used as controls. At 90 days post-surgery, the muscular atrophy on the right upper lip was more evident in the nerve growth factor and normal sa-line groups than in the nerve growth factor-microspheres and autologous nerve groups. physiological analysis revealed that the nerve conduction velocity and amplitude were significantly higher in the nerve growth factor-microspheres and autologous nerve groups than in the nerve growth factor and normal saline groups. Moreover, histological observation illustrated that the di-ameter, number, alignment and myelin sheath thickness of myelinated nerves derived from rabbits were higher in the nerve growth factor-microspheres and autologous nerve groups than in the nerve growth factor and normal saline groups. These findings indicate that chitosan nerve conduits bined with microspheres for sustained release of nerve growth factor can significantly improve facial nerve defect repair in rabbits.