Influence of Touch-Spun Fibers Diameter on Neurite Outgrowth and Schwann Cell Migration

Introduction: Peripheral nerve repair across large gaps represents a clinical challenge. One solution is the development of implantable polymeric scaffolds as alternatives to autografts. Nanofibrous scaffolds are ideal for tissue engineering applications because their dimensions are similar to the components in the extracellular matrix and they can be seeded with cells to facilitate regeneration. We will investigate the effects of nanofiber diameter on a Dorsal root ganglia (DRG) whole tissue system and on a Schwann cell (SC) single cell system.

Materials and Methods: Fiber preparation: Aligned touch-spun PCL fibers of four different fiber diameter groups ranging from 300 nm to 900 nm were fabricated. The touch-spun samples were characterized using a field emission scanning electron microscope (SEM). Cell Culture: DRG were obtained from Sprague Dawley rats and cultured on surfaces for 7 days. The effect of fiber diameter on SC emigration and neurite length was examined using immunohistochemistry. Lastly, primary SCs were used to examine single cell migration behaviors on the nanofiber and control groups including cell alignment, velocity (µm/min) and diffusivity. Statistical differences between groups were determined using ANOVA, with p<0.05. Data are presented as the mean ± standard deviation.

Results and Discussion: Analysis of neurite length showed 700 nm fibers had significantly longer neurites than the plastic control. SC emigration was significantly more elongated along the all fiber groups compared to the controls. Single SC migration showed that cell alignment increased with fiber diameter. Also, fiber samples showed diffusive results regardless of diameter. Lastly, 900 nm fibers had significantly higher Instantaneous Velocity (µm/min) compared to the other fiber groups. Thus, fibers enhanced alignment of SC migration but did not produce a directional effect. Overall, larger fibers promote regeneration but, more work is needed for further examination of the mechanisms involved.