| Currently, there is no satisfactory treatment for peripheral nerve injury. Despite the plethora of research conducted in this field, there is still no clinically available nerve guidance conduit, which has surpassed the efficacy of the field's gold standard, the autologous nerve graft. The autologous nerve graft, however, is plagued with a variety of clinical complications, such as donor site morbidity, limited availability, nerve site mismatch, and the formation of neuromas. Thus, the development of a nerve guidance conduit (NGC), which could match the effectiveness of the autologous nerve graft, would be beneficial to the field of peripheral nerve surgery. Design strategies have recently included the development of biopolymers and synthetic polymers as primary scaffolds with tailored mechanical and physical properties, luminal "fillers" such as laminin and fibronectin as secondary internal scaffolds, surface micropatterning, and controlled release of neurotrophic factors. Peripheral nerve regeneration is a complex process. Recent research has suggested that a combination of the above strategies will yield successful treatments for peripheral nerve injury.;To encourage directional neurite outgrowth in vitro, anisotropic silk fibroin films of varying dimensions were created and screened for optimized alignment, using the P19 cell line. After determining the optimal micropattern dimensions, the silk fibroin films were then seeded with neuronally differentiated PC-12 cells and assessed for cellular alignment in an automated process.;Cellular alignment is traditionally assessed using manually drawn vectors connecting the neurite's end to the source on the soma. We wanted to develop an automated process, which would assess the orientation of the neuron soma, which has eccentricity in the direction of neurite outgrowth. In order to objectively assess PC-12 cellular alignment on the silk films, the Gauss-Newton algorithm was used to solve a nonlinear least squares problem, which approximates the neuron's soma and the proximal portions of the neurites as an ellipse. We found that this algorithm could accurately assess cellular alignment in the earlier stages of differentiation for the PC-12 cell line.;After developing anisotropic films for nerve regeneration applications, we were interested in controlled drug release for optimized peripheral nerve response. In vitro bioassays investigated the efficacy of different release profiles of glial cell line-derived neurotrophic factor (GDNF). We found that this neurotrophic factor can have long-term, controlled release profiles and that the neurotrophic factors retain their bioactivity throughout this process.;The goal of peripheral nerve repair is to promote the robust regenerative response of the proximal nerve cable, so that it may eventually grow through its distal end, and recover functionality through synapsing with its original output. Nerve regeneration is a complex process that requires the presence of numerous factors, signaling cues, and design parameters to be successful. The above developments are a step forward in the development of a comprehensive nerve guidance conduit, which could provide an alternative solution to the autologous nerve graft. |
