Bionic materials for neuromuscular restoration and maintenance
Effective engineering of skeletal muscle requires platforms that facilitate the proliferation and maintenance of primary muscle stem cells (myoblasts) and muscle fibre maturation in a manner that reflects native muscle structure. In addition, the supporting scaffold needs to accommodate the correct innervation of the re-engineered muscle tissue by promoting axonal connection and neuromuscular junction formation. We have been investigating the use of micro and nano-structured conducting polymer surfaces for ex vivo muscle and nerve growth, differentiation and trophic electrical stimulation. Micro-structured platforms were created by localization of wet-spun PLA:PLGA fibers onto polypyrrole substrate, whilst nano-structured platforms were created by orientation of carbon nanotube fibres on a conducting gold mylar surface, over which a layers of polypyrrole were deposited. Human and murine myoblasts and rat dorsal root ganglion explants (sensory nerve) were grown and/or differentiated on these platforms. A significant effect on myotube orientation was seen on both micro and nano-structured surfaces whilst surface topography similarly influenced the direction in which elements of the DRG cellular components grew. Growth of muscle cells as well as sensory nerve components (Scwhann cells and axons) on both nano and micro-structured polypyrrole was increased by electrical stimulation, providing a novel model system by which the effective innervation of regenerating muscle can be explored.