Aligned electrospun nanofibers direct neurite growth and may prove effective for repair throughout the nervous system. Applying nanofiber scaffolds to different nervous system regions will require prior in vitro testing of scaffold designs with specific neuronal and glial cell types. This would be best accomplished using primary neurons in serum-free media; however, such growth on nanofiber substrates has not yet been achieved. Here we report the development of poly(L-lactic acid) (PLLA) nanofiber substrates that support serum-free growth of primary motor and sensory neurons at low plating densities. In our study, we first compared materials used to anchor fibers to glass to keep cells submerged and maintain fiber alignment. We found that poly(lactic-co-glycolic acid) (PLGA) anchors fibers to glass and is less toxic to primary neurons than bandage and glue used in other studies. We then designed a substrate produced by electrospinning PLLA nanofibers directly on cover slips pre-coated with PLGA. This substrate retains fiber alignment even when the fiber bundle detaches from the cover slip and keeps cells in the same focal plane. To see if increasing wettability improves motor neuron survival, some fibers were plasma etched before cell plating. Survival on etched fibers was reduced at the lower plating density. Finally, the alignment of neurons grown on this substrate was equal to nanofiber alignment and surpassed the alignment of neurites from explants tested in a previous study. This substrate should facilitate investigating the behavior of many neuronal types on electrospun fibers in serum-free conditions.

Neuritogenesis, neuronal polarity formation, and maturation of axons and dendrites are strongly influenced by both biochemical and topographical extracellular components. The aim of this study was to elucidate the effects of polylactic acid (PLLA) electrospun fiber topography on primary motor neuron development, since regeneration of motor axons is extremely limited in the central nervous system and could potentially benefit from the implementation of a synthetic scaffold to encourage re-growth. In this analysis, we found that both aligned and randomly-oriented submicron fibers significantly accelerated the processes of neuritogenesis and polarity formation of individual cultured motor neurons compared to flat polymer films and glass controls, likely due to restricted lamellipodia formation observed on fibers. In contrast, dendritic maturation and soma spreading were inhibited on fiber substrates after 2 days in vitro. This study is the first to examine the effects of electrospun fiber topography on motor neuron neuritogenesis and polarity formation. Aligned nanofibers were shown to affect the directionality and timing of motor neuron development, providing further evidence for the effective use of electrospun scaffolds in neural regeneration applications.

No abstract

No abstract