STIMULATION OF NEURITE OUTGROWTH USING AN ELECTRICALLY CONDUCTING POLYMER

Damage to peripheral nerves often cannot be repaired by the juxtaposit ion of the severed nerve ends, Surgeons have typically used autologous nerve grafts, which have several drawbacks including the need for mul tiple surgical procedures and loss of function at the donor site. As a n alternative, the use of nerve guidance channels to bridge the gap be tween severed nerve ends is being explored. In this paper, the electri cally conductive polymer-oxidized polypyrrole (PP)-has been Evaluated for use as a substrate to enhance nerve cell interactions in culture a s a first step toward potentially using such polymers to stimulate iir who nerve regeneration, Image analysis demonstrates that PC-12 cells and primary chicken sciatic nerve explants attached and extended neuri tes equally well on both PP firms and tissue culture polystyrene in th e absence of electrical stimulation, In contrast, PC-12 cells interact ed poorly with indium tin oxide (ITO), poly(L-lactic acid) (PLA), and poly(lactic acid-co-glycolic acid) surfaces, However, PC-12 cells cult ured on PP films and subjected to an electrical stimulus through the f ilm showed a significant increase in neurite lengths compared with one s that were not subjected to electrical stimulation through the film a nd tissue culture polystyrene controls, The median neurite length for PC-12 cells grown on PP and subjected to an electrical stimulus was 18 .14 mu m (n = 5643) compared with 9.5 mu m (n = 4440) for controls, Fu rthermore, animal implantation studies reveal that PP invokes little a dverse tissue response compared with poly(lactic acid-co-glycolic acid ).