| Well-defined neurotrophic factor concentration gradients were prepared using a compartmented diffusion chamber. This model system was employed to study the chemotactic effect of neurotrophic factors to guide neurite outgrowth. The information obtained from this model system may provide insights into the designs of a biomimetic device to enhance nerve regeneration after spinal cord injuries.; Specifically, by maintaining the concentrations in both the source and sink compartments constant (and different), a linear NGF concentration profile was achieved within the agarose membrane through which a steady state diffusion was established. The well-defined linear NGF concentration profile enabled the quantification of the minimum concentration gradient required to guide neurite outgrowth using PC12 cells as a model cell line for neurons.; Furthermore, multiple concentration gradients of different neurotrophic factors were prepared using similar compartmented diffusion chambers. The synergistic guidance effect of multiple factors observed in this model system suggests that peripheral dorsal root ganglion cell neurite outgrowth can be guided over an extended distance. This result could warrant the incorporation of neurotrophic factor concentration gradient into a nerve regeneration device to guide and augment nerve fiber regeneration.; Finally, in an attempt to translate the neurotrophic concentration gradient guidance into an artificial device that may enhance CNS regeneration, efforts were also made immobilize biomolecules in a three-dimensional agarose hydrogel using photoimmobilization. The improved photoimmobilization yield using the photoactive agarose gel approach, as a result of the enhanced interactions between the photoactive moieties and the agarose gel, represented a viable approach to immobilize biomolecules in 3D hydrogel matrices. This approach could also be further advanced to photoimmobilize biomolecule concentration gradients in situ. |
