Electrospinning of PELA/PPY Fibrous Conduits: Promoting Peripheral Nerve Regeneration in Rats by Self-Originated Electrical Stimulation

Abstract

Peripheral nerve injuries represent a great challenge for surgeons. The conductive neural scaffold has experienced increasing interest because of its good biocompatibility and similar electrical properties as compared to those of a normal nerve. Herein, nerve conduits made from poly­(d,l-lactide)-co-poly­(ethylene glycol) and polypyrrole (20%, 30%, and 50%) (PELA–PPY) were prepared by electrospinning, and used in regeneration of peripheral nerve defects. The results of an in vitro experiment indicated a high biocompatibility for the as-prepared materials, supporting the attachment and proliferation of a rat pheochromocytoma PC-12 cell. Furthermore, the PELA–PPY nerve conduit implanted in the sciatic nerve defects (10 mm) of the Spraguee–Dawley rats for 12 weeks showed similar results with the autograft, while it demonstrated a better outcome than the PELA nerve conduit in electrophysiological examination, sciatic function index, total amount of regenerated myelinated nerve fibers, axon diameter, myelin thickness, and several immunohistochemistry indices (S-100, laminin, neurofilament, bromodeoxyuridine, and glial fibrillary acidic portein). We supposed that the bioactivity is mainly generated by the PPY in composite nanofibers which could transmit self-originated electrical stimulation between cells. Due to the facile preparation and excellent in vivo performance, the PPY–PELA nerve conduit is promising for use as a bioengineered biomaterial for peripheral nerve regeneration.

Intact polyaniline coating as a conductive guidance is beneficial to repairing sciatic nerve injury

“…In our study, the similar results were obtained, which demonstrated that the recovery of nerve conduction and nerve function were structurally based on the regeneration of myelinated axons . Liu et al considered that the incorporation of conducting polymers can promote the neurite outgrowth owing to their effect on modifying the living microenvironment of neurons through transmitting the self‐originated electrical stimulation to regenerated nerve cells . Ho et al found that conductive polymer such as poly(3,4‐ethylenedioxythiophene)‐poly(styrenesulfonate) nanoparticles could increase the surface area of the conduit and enhance neurite outgrowth and spreading on substrate when used as a coating material at the form of film .…”

“…The better repairing effect of conduits may be obtained further by designing a three‐dimensional conductive conduit. In recent years, conducting polymers such as polypyrrole, polythiophene, and PANi have been reported to repair nerve injuries . The challenge is that PANi cannot be degraded.…”

“…The regenerated vessels in both the conduit groups with and without PANi coating had achieved the similar level as in the autograft group, which can also provide enough nutrient support for nerve regeneration. The conductivity and functional recovery of nerve are depended on the total number of the regenerated nerves, the axon diameter, myelin sheath thickness, and internode length . The structural analysis of regenerated nerve revealed that the autograft achieved the best recovery in the number of regenerated nerve fibers and the myelin sheath thickness at both the second month and the fourth month [Figure (B,C)].…”

“…Recent studies have been focused on improving the repairing effect of conduits through different methods such as filling guiding cues into conduits, 1,2 developing multichannel conduits or preparing the conduits with nanotopography and conductivity. [3][4][5] The neurons have the character of transducing electrical signals. The conductivity has been considered as an important parameter when designing an ideal nerve conduit.…”

Optimal electrical stimulation boosts stem cell therapy in nerve regeneration

“…While conductive conduits have shown the ability to induce neuronal differentiation of PC12 cells in vivo [52] and promoting sciatic nerve regeneration in rat models by transmitting self- originated electrical stimulation between cells [53], in our study, we used external electrical stimulation on transplanted NCSCs to promote the Schwann cell differentiation and nerve regeneration. The polycaprolactone nanofiber we used is not a conductive material; however, the hydrogel + PBS filling is.…”