Spinal cord injury (SCI) results in permanent motor and sensory deficits, primarily caused by localized cell death. Treatment strategies which focus on guiding cell behavior (exogenous or endogenous) are attractive. Neural stem cells (NSCs) can contribute to recovery indirectly (secreted neurotrophic factors) or directly (by differentiating into functional cell types). Their efficacy is also clearly enhanced with an active biomaterial carrier to keep them within the site of injury and guide their behavior.

Here, a biomaterial-based approach for treating SCI was investigated, consisting of NSCs seeded within a biomimetic scaffold made from methacrylamide chitosan (MAC). The scaffold contained tethered, biotinylated recombinant growth factors to specify the lineage of the encapsulated NSCs. This scaffold showed promising tissuelevel improvements but failed to restore locomotor function. Next, a new approach for covalently immobilizing azide-tagged recombinant proteins was developed. This approach was tested on interferon-γ (IFN-γ, which induces neuronal differentiation from NSCs) and found to enable immobilization to multiple materials while retaining its bioactivity. A new, open-source gait analysis technique was then adapted to include SCI-specific parameters. This technique was tested on a treatment which is known to be effective, intracellular σ peptide (ISP, which reduces inhibitory cues from the microenvironment) and found to sensitively measure benefits. The NSC-seeded scaffolds were tested again, with two major improvements:​ they were primed in subcutaneous tissue prior to transplantation into the spinal cord and ISP was coadministered. This approach was based on a finding that NSC-seeded scaffolds with immobilized IFN-γ increased the expression of developmental markers after subcutaneous maturation. Ultimately, subcutaneous maturation with ISP was found to improve function. The tissue-level analysis suggested that this was due to an indirect pro-regenerative effect of the NSCs within the scaffolds, which is enhanced by both subcutaneous priming and ISP administration. Finally, a method for enabling the controlled release of soluble proteins from this system was developed. Methacrylated heparin was introduced into MAC hydrogel scaffolds with immobilized IFN-γ and observed to slow the release of soluble stromal cell-derived factor-1α (SDF-1α), which enabled NSC recruitment to the scaffold in vitro where they then differentiated into neurons following exposure to immobilized IFN-γ. In general, this work sought to develop and test new approaches to improve NSC-seeded biomaterials for treating SCI.