The cellular response of nerve cells on poly-l-lysine coated PLGA-MWCNTs aligned nanofibers under electrical stimulation

Abstract

Tissue engineering scaffold provide an effective alternative for peripheral nerve repair. Nanofibrous nerve conduits fabricated with various synthetic and natural materials have great potential to support nerve regeneration as a bridge between adjacent ends. The physical, chemical and electrical properties of the scaffolds affect the outcome of nerve regeneration and recovery of function. In this paper, a surface modified, electrically conductive, aligned nanofibrous scaffold composed of poly(lactic-co-glycolic acid) (PLGA) and multi-walled carbon nanotubes (MWCNTs), referred to as L-PC_A was fabricated for nerve regeneration. The morphology, surface chemistry and hydrophilicity of nanofibers were characterized by Scanning Electron Microscopy (SEM), Energy-dispersive X-ray (EDX) and water contact angle, respectively. The mechanical property of the nanofibrous scaffold was also evaluated using a universal materials tester. The effects of these scaffolds on PC12 cell adhesion, proliferation and neuronal differentiation were all evaluated. A hydrophilic surface was created by poly-l-lysine coating, which was able to provide a better environment for cell attachment. Furthermore aligned fibers were proved to be able to guide PC12 cells and DRG neurons growing along the fiber direction and be beneficial for neurite outgrowth. The cellular responses of PC12 cells and DRG neurons on L-PC_A scaffold under electrical stimulation were evaluated by neurofilament proteins expression. As a result, the PC12 cells and DRG neurons stimulated with electrical shock showed longer neurite length, indicating that electrical stimulation with a voltage of 40 mV based on the scaffold with MWCNTs could enhance the neurite extension. Moreover, the cellular response of Schwann cells including cell attachment, proliferation and MBP expression were also enhanced with the synergistic effect of aligned nanofibers and electrical stimulation. In summary, the L-PC_A nanofibrous scaffold supported the cellular response of nerve cells in terms of cell proliferation, differentiation, neurite outgrowth, and myelination in the presence of electrical stimulation, which could be a potential candidate for nerve regeneration application.

Keywords: Aligned nanofibers; Electrical stimulation; MWCNTs; Nerve cells; Surface modification.