Stimulation of neurite outgrowth using an electrically conducting polymer

Abstract

Damage to peripheral nerves often cannot be repaired by the juxtaposition of the severed nerve ends. Surgeons have typically used autologous nerve grafts, which have several drawbacks including the need for multiple surgical procedures and loss of function at the donor site. As an alternative, the use of nerve guidance channels to bridge the gap between severed nerve ends is being explored. In this paper, the electrically conductive polymer-oxidized polypyrrole (PP)-has been evaluated for use as a substrate to enhance nerve cell interactions in culture as a first step toward potentially using such polymers to stimulate in vivo nerve regeneration. Image analysis demonstrates that PC-12 cells and primary chicken sciatic nerve explants attached and extended neurites equally well on both PP films and tissue culture polystyrene in the absence of electrical stimulation. In contrast, PC-12 cells interacted poorly with indium tin oxide (ITO), poly(L-lactic acid) (PLA), and poly(lactic acid-coglycolic acid) surfaces. However, PC-12 cells cultured on PP films and subjected to an electrical stimulus through the film showed a significant increase in neurite lengths compared with ones that were not subjected to electrical stimulation through the film and tissue culture polystyrene controls. The median neurite length for PC-12 cells grown on PP and subjected to an electrical stimulus was 18.14 m (n ‫؍‬ 5643) compared with 9.5 m (n ‫؍‬ 4440) for controls. Furthermore, animal implantation studies reveal that PP invokes little adverse tissue response compared with poly(lactic acid-coglycolic acid).

Conducting polymer-hydrogels for medical electrode applications

“…Many CPs have demonstrated negligible toxicity across a wide range of cell types and explants, including clonal neural cells [1,2,11,140], primary neuroblastomas [59], cardiomyocytes [141], glial cells [59] and spiral ganglion explants [20]. It has also been shown that CPs provide a more conducive environment for cell attachment and growth than bare metal electrodes [1,13], and that CPs loaded with neurotrophins can stimulate neurite growth of target cells [2,6,69].…”

Electrochemically controlled release of dexamethasone from conducting polymer polypyrrole coated electrode

“…Polypyrrole and its derivatives are the most widely used conducting polymers in biomedical applications due to their biocompatibility and customizability [31][32][33][34][35][36]. Polypyrrole has been electrically deposited onto the electrode site of the neural recording arrays together with CDPGYIGSR, a peptide fragment from laminin [9,37], to improve the neuron-electrode connection in vivo.…”

Tunable conjugated polymers for bacterial differentiation

“…They have been used for bio-sensing [5][6][7], as electrodes for stimulation or recording [8,9], for controlling cell adhesion, proliferation [10][11][12] and stem-cell differentiation [13], for controlled drug release [14,15] and even to mechanically stimulate cells [16]. They can be fabricated electrochemically using various counter ions [17,18] and modified with a variety of biomolecules [5,6,19].…”