Polypyrrole-coated poly(l-lactic acid-co-ε-caprolactone)/silk fibroin nanofibrous nerve guidance conduit induced nerve regeneration in rat

According to our previous study, polypyrrole (Ppy) possessed good conductivity and non-cytotoxicity. In this study, the surface of electrospun poly(l-lactic-acid-co-epsilon-caprolactone)/silk fibroin (PLCL/SF) was coated with Ppy to fabricate Ppy-coated nerve guidance conduit (NGC). Firstly, the presence of Ppy on the prepared NGC was characterized and confirmed by scanning electron microscopy (SEM), X-ray photoelectron spectroscopic spectra (XPS) and Fourier transforms infrared spectroscopy (FTIR). Subsequently, Ppy-coated NGC was used to repair a 10 mm sciatic nerve gap in vivo. 4 and 12 weeks after implantation, the regenerated nerve tissues on defect sites were removed and sectioned for further evaluation. Histological analysis with hematoxylin-eosin (HE), toluidine blue (TB), and luxol fast blue (LFB) staining indicated that the coated Ppy could promote SCs proliferation in early post-surgery, and enhance myelin formation in later post-surgery. In consideration of immunofluorescence and morphology observation with SEM and TEM, it showed that the nerve regeneration of Ppy-coated NGC group was close to autograft group, which was better than PLCL/SF NGC. In addition, walking track analysis indicated that Ppy-coated NGC group showed a similar performance compared with the autograft group, and significantly better than PLCL/SF NGC group. These promising results showed the potential of Ppy-coated NGC in peripheral nerve regeneration.