Electrically Conductive Biodegradable Polymer Composite for Nerve Regeneration: Electricity‐Stimulated Neurite Outgrowth and Axon Regeneration

TLDR

The study evaluated newly developed electrically conductive biodegradable polymer composites using PC12 cell cultures and nerve guidance channel implantation. They cultured PC12 cells on conductive membranes, applied direct current at various intensities, and implanted conductive composite nerve guidance channels into rats, harvesting after two months for histological analysis. PPy doped with butane sulfonic acid supported higher cell viability, and electrical stimulation at 1.7–8.4 µA/cm promoted maximal neurite outgrowth; in rats, the conductive composite guided channels regenerated myelinated axons and Schwann cells comparable to native nerve, demonstrating current‑dependent neurite outgrowth and successful sciatic nerve regeneration.

Abstract

Normal and electrically stimulated PC12 cell cultures and the implantation of nerve guidance channels were performed to evaluate newly developed electrically conductive biodegradable polymer composites. Polypyrrole (PPy) doped by butane sulfonic acid showed a significantly higher number of viable cells compared with PPy doped by polystyrenesulfonate after a 6-day culture. The PC12 cells were left to proliferate for 6 days, and the PPy-coated membranes, showing less initial cell adherence, recorded the same proliferation rate as did the noncoated membranes. Direct current electricity at various intensities was applied to the PC12 cell-cultured conductive membranes. After 7 days, the greatest number of neurites appeared on the membranes with a current intensity approximating 1.7-8.4 microA/cm. Nerve guidance channels made of conductive biodegradable composite were implanted into rats to replace 8 mm of sciatic nerve. The implants were harvested after 2 months and analyzed with immunohistochemistry and transmission electron microscopy. The regenerated nerve tissue displayed myelinated axons and Schwann cells that were similar to those in the native nerve. Electrical stimulation applied through the electrically conductive biodegradable polymers therefore enhanced neurite outgrowth in a current-dependent fashion. The conductive polymers also supported sciatic nerve regeneration in rats.