Injectable, magnetically-orienting electrospun fiber conduits for neuron guidance.

Magnetic electrospun fibers are of interest to biomaterial applications that strive to provide cell guidance that can be delivered using minimally invasive techniques. Magnetic electrospun fibers can be injected then magnetically positioned in situ, and the aligned fiber scaffolds provide consistent topographical guidance to cells. We developed and tested magnetically-responsive aligned poly-L-lactic acid (PLLA) electrospun fiber scaffolds for neural applications. Incorporating oleic-acid-coated iron oxide nanoparticles significantly increased neurite outgrowth, reduced the fiber alignment, and increased the surface nanotopography of the electrospun fibers. After verifying neuron viability on two-dimensional scaffolds, the system was tested as an injectable three-dimensional scaffold. Small conduits of aligned magnetic fibers were easily injected in a collagen or fibrinogen hydrogel solution and repositioned using an external magnetic field. The aligned magnetic fibers provided internal directional guidance to neurites within a three-dimensional collagen or fibrin model hydrogel, supplemented with Matrigel. Neurites growing from a dorsal root ganglia explant extended 1.4-3x farther on the aligned fibers compared to neurites extending in the hydrogel alone. Overall, these results show that magnetic electrospun fiber scaffolds can be injected and manipulated with a magnetic field in situ to provide directional guidance to neurons inside an injectable hydrogel. Most importantly, this injectable guidance system increased both neurite alignment and neurite length within the hydrogel scaffold.