An Analysis of Time-Dependent Changes of Neurotrophic Factors (BDNF, CNTF) in Traumatic Facial Nerve Injury of a Nerve-Cut and Nerve-Crush Model in Rats

Combining acellular nerve allografts with brain-derived neurotrophic factor transfected bone marrow mesenchymal stem cells restores sciatic nerve injury better than either intervention alone

In this study, we chemically extracted acellular nerve allografts from bilateral sciatic nerves, and repaired 10-mm sciatic nerve defects in rats using these grafts and brain-derived neurotrophic factor transfected bone marrow mesenchymal stem cells. Experiments were performed in three groups: the acellular nerve allograft bridging group, acellular nerve allograft + bone marrow mesenchymal stem cells group, and the acellular nerve allograft + brain-derived neurotrophic factor transfected bone marrow mesenchymal stem cells group. Results showed that at 8 weeks after bridging, sciatic functional index, triceps wet weight recovery rate, myelin thickness, and number of myelinated nerve fibers were significantly changed in the three groups. Variations were the largest in the acellular nerve allograft + brain-derived neurotrophic factor transfected bone marrow mesenchymal stem cells group compared with the other two groups. Experimental findings suggest that chemically extracted acellular nerve allograft combined nerve factor and mesenchymal stem cells can promote the restoration of sciatic nerve defects. The repair effect seen is better than the single application of acellular nerve allograft or acellular nerve allograft combined mesenchymal stem cell transplantation.

Chemically extracted acellular allogeneic nerve graft combined with ciliary neurotrophic factor promotes sciatic nerve repair

A chemically extracted acellular allogeneic nerve graft can reduce postoperative immune rejection, similar to an autologous nerve graft, and can guide neural regeneration. However, it remains poorly understood whether a chemically extracted acellular allogeneic nerve graft combined with neurotrophic factors provides a good local environment for neural regeneration. This study investigated the repair of injured rat sciatic nerve using a chemically extracted acellular allogeneic nerve graft combined with ciliary neurotrophic factor. An autologous nerve anastomosis group and a chemical acellular allogeneic nerve bridging group were prepared as controls. At 8 weeks after repair, sciatic functional index, evoked potential amplitude of the soleus muscle, triceps wet weight recovery rate, total number of myelinated nerve fibers and myelin sheath thickness were measured. For these indices, values in the three groups showed the autologous nerve anastomosis group > chemically extracted acellular nerve graft + ciliary neurotrophic factor group > chemical acellular allogeneic nerve bridging group. These results suggest that chemically extracted acellular nerve grafts combined with ciliary neurotrophic factor can repair sciatic nerve defects, and that this repair is inferior to autologous nerve anastomosis, but superior to chemically extracted acellular allogeneic nerve bridging alone.

Induction of rat facial nerve regeneration by functional collagen scaffolds

Nerve conduit provides a promising strategy for nerve regeneration, and the proper microenvironment in the lumen could improve the regeneration. Our previous work had demonstrated that linear ordered collagen scaffold (LOCS) could effectively guide the oriented growth of axons. Laminin is known as an important nerve growth promoting factor and can facilitate the growth cone formation. In addition, ciliary neurotrophic factor (CNTF) and brain-derived neurotrophic factor (BDNF) can effectively improve the nerve regeneration after nerve injuries. However, in practice, diffusion caused by the body fluids is the major obstacle in their applications. To retain CNTF or BDNF on the scaffolds, we produced collagen binding CNTF (CBD-CNTF), collagen binding BDNF (CBD-BDNF) and laminin binding CNTF (LBD-CNTF), laminin binding BDNF (LBD-BDNF) respectively. In this work, we developed laminin modified LOCS fibers (L × LOCS) by chemical cross-linking LOCS fibers with laminin. Collagen binding or laminin binding neurotrophic factors were combined with LOCS or L × LOCS, and then filled them into the collagen nerve conduit. They were found to guide the ordered growth of axons, and improve the nerve functional recovery in the rat facial nerve transection model. The combination of CNTF and BDNF greatly enhanced the facial nerve regeneration and functional recovery.

Differences in sensitivity to rocuronium among orbicularis oris muscles innervated by normal or damaged facial nerves and gastrocnemius muscle innervated by somatic nerve in rats: combined morphological and functional analyses

OBJECTIVES/HYPOTHESIS

To evaluate mechanisms of discrepant responses to the nondepolarizing muscle relaxant rocuronium among normal and injured facial nerve-innervated orbicularis oris and tibial nerve-innervated gastrocnemius, and to provide information for the proper use of muscle relaxants to balance evoked electromyography (EEMG) monitoring and immobility in general anesthesia.

STUDY DESIGN

Randomized controlled study.

METHODS

Right-sided facial nerve injury was induced by crush axotomy in 18 Sprague-Dawley rats. At different rocuronium concentrations, muscular tension amplitude (MTA) was determined in vitro for normal and injured facial nerve-innervated orbicularis oris and gastrocnemius; the number of unsaturated acetylcholine receptors (AChRs) at end plates was determined by (125) I-α-bungarotoxin staining followed with gamma spectroscopy. The morphological composition of muscle fibers was determined by histological examination.

RESULTS

Following rocuronium incubation, the percentage of MTA inhibition (MTAI%) of gastrocnemius was significantly higher than the corresponding values of orbicularis oris (P < .05), and the degree of saturation of AChR in gastrocnemius was significantly greater than that in orbicularis oris (P < .05). The baseline MTA and AChR density of injured-side orbicularis oris was significantly smaller than those of the normal side, whereas no significant difference was found regarding MTAI% and the degree of AChR saturation between the normal and injured side.

CONCLUSIONS

The affinity of AChR at end plates and different number of AChR per unit fiber cross-sectional area may be the mechanisms for differential sensitivities to neuromuscular blockers between facial nerve-innervated muscles and somatic nerve-innervated muscles. The lower EEMG responses in the impaired facial nerve-innervated muscles may result from the lower AChR density at end plates compared with the normal facial nerve-innervated muscles.