Effects of Schwann cell alignment along the oriented electrospun chitosan nanofibers on nerve regeneration.

We have constructed a chitosan nonwoven nanofiber mesh tube consisting of oriented fibers by the electrospinning method. The efficacy of oriented nanofibers on Schwann cell alignment and positive effect of this tube on peripheral nerve regeneration were confirmed. The physical properties of the chitosan nanofiber mesh sheets prepared by electrospinning with or without fiber orientation were characterized. Then, immortalized Schwann cells were cultured on these sheets. Furthermore, the chitosan nanofiber mesh tubes with or without orientation, and bilayered chitosan mesh tube with an inner layer of oriented nanofibers and an outer layer of randomized nanofibers were bridgegrafted into rat sciatic nerve defect. As a result of fiber orientation, the tensile strength along the axis of the sheet increased. Because Schwann cells aligned along the nanofibers, oriented fibrous sheets could exhibit a Schwann cell column. Functional recovery and electrophysiological recovery occurred in time in the oriented group as well as in the bilayered group, and approximately matched those in the isograft. Furthermore, histological analysis revealed that the sprouting of myelinated axons occurred vigorously followed by axonal maturation in the isograft, oriented, and bilayered group in the order. The oriented chitosan nanofiber mesh tube may be a promising substitute for autogenous nerve graft.