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Peripheral nerve injury (PNI) is common, with over 5 million global cases annually. Autologous nerve grafting, the gold - standard treatment, has donor - site issues and suboptimal recovery. Thus, researchers aim to develop nerve guidance conduits (NGCs). Traditional hollow NGCs have regenerative potential but are limited in large nerve defects due to lacking biophysical cues and mechanical stability. To address this, NGCs with inner - layer oriented nanofibers were developed to guide cell growth and axonal regeneration.Moreover, adding conductive materials to NGCs is promising as nerve cells respond to electrical stimulation. Poly(3,4 - ethylenedioxythiophene) (PEDOT) is a top - choice conductive material due to its conductivity and stability. However, its insolubility restricts application. So, researchers combined PEDOT with hydroxyethyl cellulose (HEC) to create a stable conductive composite.
This study developed a helical-structured electrospun conductive conduit (F-P/H-P) for peripheral nerve regeneration, which is filled with oriented nanofibers inside. The electrospinning machine was used to fabricate this conduit, and by combining hydroxyethyl cellulose (HEC) and poly(3,4-ethylenedioxythiophene) (PEDOT), the electrical conductivity of the conduit was significantly improved. Experimental results showed that this conductive conduit could significantly enhance the adhesion and proliferation of Schwann cells (SCs) and PC12 cells, and further promote the expression of nerve-related proteins under electrical stimulation (ES). In vivo experiments using a rat model of sciatic nerve defect confirmed that the F-P/H-P conduit could significantly accelerate nerve regeneration, angiogenesis, and functional recovery. This study demonstrates the great potential of this novel conductive NGCs in promoting peripheral nerve regeneration and functional repair, providing an effective alternative for nerve repair.
Schematic diagram of the conductive F-P/H-P NGCs promoting nerve regeneration under electrical stimulation
(1) Synergistic Advantages of NGCs
This study systematically highlighted the synergistic advantages of combining conductive materials with biomimetic structural features. Advanced helical-structured conductive F-P/H-P NGCs were fabricated by using an electrospinning device. These NGCs are filled with oriented nanofibers inside, which can effectively promote the complex process of nerve repair and functional recovery. As can be seen in Figures 1A and B, the P/H and P/H-P nanofibers have uniform and smooth fibers and interconnected pores, and the fiber diameter of the P/H-P group is smaller, indicating that the addition of PEDOT has a significant impact on the formation and properties of the fibers. The mechanical test results in Figures 1G and H show that after the addition of PEDOT, the tensile strength of the conduit is significantly increased, from 5.7 ± 0.6 MPa to 9.3 ± 1.2 MPa, and the tensile strength of the F-P/H-P conduit is better than that of the H-P/H-P conduit, indicating that the helical structure further enhances the mechanical properties of the conduit.
Figure 1. Characterization of NGCs.
(2) Superior Cell Adhesion and Proliferation
In vitro experimental results showed that the excellent electrical conductivity of the F-P/H-P NGCs significantly promoted the adhesion and proliferation of Schwann cells (SCs) and PC12 cells. This cellular response contributes to the improvement of nerve regeneration and functional recovery. As can be seen in Figures 2J and K, the results of the CCK-8 assay showed that the P/H-P membrane significantly promoted the proliferation of SCs and PC12 cells under electrical stimulation (ES). In the ES-P/H-P group, the proliferation rates of SCs and PC12 cells were significantly higher than those in other groups at 3 days and 5 days. The scanning electron microscopy (SEM) observation in Figure 2 showed that SCs and PC12 cells exhibited the best adhesion effect on the P/H-P material, especially in the ES-P/H-P group, where the cells grew along the oriented nanofibers, showing a longer morphology and a larger adhesion area.
Figure 2. Adhesion, proliferation, and migration of SCs and PC12 cells on P/H, ES-P/H, P/H-P, and ES-P/H-P membranes.
(3) Advantages in Nerve Regeneration and Functional Recovery
The results of multiple experiments have demonstrated the advantages of using conductive conduits filled with oriented nanofibers for nerve repair. This design effectively mimics the biophysical cues inherent in the natural peripheral nerve, creating an environment conducive to nerve regeneration. As can be seen in Figure 3, the results of the H&E staining showed that the F-P/H-P conduit exhibited significantly higher nerve tissue regeneration ability at 12 weeks, and the area and quantity of the regenerated nerve tissue were comparable to those of the autologous transplantation group.
Figure 3. Histological morphology evaluation of autologous transplantation, P/H, H-P/H-P, and F-P/H-P conduits.
The results of the immunofluorescence staining in Figure 4 showed that the expression levels of S100 and NF200 in the F-P/H-P group at 12 weeks were comparable to those in the autologous transplantation group, indicating that this conduit could effectively promote myelin formation and axonal extension.
Figure 4. Immunofluorescence staining of autologous transplantation, P/H, H-P/H-P, and F-P/H-P conduits at 12 weeks.
(4) Verification of Functional Recovery
The helical-structured conductive F-P/H-P NGCs can also bridge nerve ruptures and provide a promising alternative for peripheral nerve repair. The electrospinning device was crucial in the fabrication process of these NGCs. The results of the muscle atrophy assessment in Figures 7A-E showed that the weight ratio of the gastrocnemius muscle in the F-P/H-P group was comparable to that in the autologous transplantation group and significantly higher than that in the P/H group, indicating that the F-P/H-P conduit could effectively promote nerve function recovery. The results of the gait analysis (SFI) in Figure 7H showed that at 12 weeks, the SFI value of the F-P/H-P group was comparable to that of the autologous transplantation group and significantly higher than those of the P/H and H-P/H-P groups, further demonstrating its advantages in nerve function recovery. The results of the electrophysiological tests in Figures 7I and J showed that at 12 weeks, the CMAP amplitude and nerve conduction velocity (NCV) of the F-P/H-P group were comparable to those of the autologous transplantation group and significantly better than those of the P/H group, indicating that the F-P/H-P conduit could effectively restore nerve conduction function. See Figure 5.
Figure 5. Functional evaluation and nerve conduction recovery 12 weeks after implantation.
This study demonstrated the synergistic benefits of integrating conductive materials with biomimetic structures. Electrospun helical - structured F - P/H - P NGCs, filled with oriented nanofibers, were developed.In vitro, their high conductivity promoted the adhesion and proliferation of Schwann cells and PC12 cells. In vivo, these NGCs effectively mimicked natural nerve biophysical cues, accelerating nerve repair and functional recovery.Overall, F - P/H - P NGCs can bridge nerve ruptures, offering a promising alternative for peripheral nerve repair.
Electrospinning Nanofibers Article Source: https://doi.org/10.1016/j.cej.2025.160899
