Enhanced neurite alignment on micro-patterned poly-L-lactic acid films.

The ability of the damaged central nervous system and peripheral nervous system to properly recover hinges on the regenerative mechanisms and functional reconnection to appropriate targets. Successful pathfinding of axons is controlled by a complex interplay of diffusible or substrate-bound biochemical and electrical cues. Physical guidance has also been shown to occur in vivo and in vitro, either via cell-cell or cell-extracellular matrix mediated contact. In the current study, we probe the role of contact guidance in facilitating neural regeneration and pathfinding. Using soft lithographic techniques, we have created thin films of poly-L-lactic acid polymer (PLLA) possessing periodic features approaching the nanometer regime. Rat PC-12 cells and chick sympathetic neurons were subsequently cultured onto these substrates and parameters, such as neurite emergence and orientation angle, neurite length, and neuronal architecture are characterized. Our results reveal that both PC-12 and chick sympathetic neurites can be effectively guided by unidirectional grooves as small as 100 nm in height and 1 microm in width. Moreover, sympathetic cells produced neurites that were longer on patterned substrata than on controls. The development of novel degradable micro/nanopatterned substrates for cell study will permit more in-depth analysis of contact mediated guidance mechanisms in addition to having applications in neural and tissue engineering.