In both the peripheral nervous system (PNS) and the central nervous system (CNS), damage due to traumatic injury can be devastating to quality of life. Some inherent regeneration occurs in the PNS, but large nerve defects require surgical intervention to restore function. Unfortunately, in the CNS, the body contains almost no natural regenerative properties. To make matters worse, cellular destruction is exacerbated due to the intrinsic response, expanding the damaged zone to encompass otherwise healthy tissue far from the original injury site. The resulting biological environment is effectively totally impermissive to surviving nerves. Advances in regeneration strategies have been forthcoming, but more work is necessary to encourage recovery on a functional level. Tissue engineered nerve guidance channels and/or surrogate permissive growth environments are thought to represent alternatives to current treatment options.

The task of designing, engineering, testing and incorporating artificial scaffolds represents an immense challenge to the tissue engineering community. Developmental guidance cues are critical to the proper mapping of the nervous system, and a growing body of evidence suggests that these signals influence adult regeneration. Therefore, an increased understanding of the underlying influences guidance molecules exert on growing axons should lead to improved regeneration strategies. A critical need exists for tunable culture environments in which structural and molecular variables can be studied for advances in understanding axonal response to environmental factors.

The focus of this dissertation encompasses the design and implementation of a novel engineered in vitro system capable of elucidating the complexities underlying neural guidance. Using a dual hydrogel approach, we demonstrated the fabrication of a choice point model capable of robust biomimetic neurite growth in a spatially defined manner that minimized inherent limitations in 3D culture models. Geometric specificity of structural and molecular patterning was possible through our use of dynamic mask photolithography. Lastly, individual and combinatorial guidance cues were examined in an easily quantifiable manner, allowing us to further the understanding of at least some factors limiting recovery following damage to the nervous system. By advancing the understanding axon outgrowth in response external stimuli, we hope to illuminate strategies for regeneration.