Hydrogel mediated delivery of trophic factors for neural repair

Neurotrophins have been implicated in a variety of diseases and their delivery to sites of disease and injury has therapeutic potential in applications including spinal cord injury, Alzheimer's disease, and Parkinson's disease. Biodegradable polymers, and specifically, biodegradable water-swollen hydrogels, may be advantageous as delivery vehicles for neurotrophins because of tissue-like properties, tailorability with respect to degradation and release behavior, and a history of biocompatibility. These materials may be designed to degrade via hydrolytic or enzymatic mechanisms and can be used for the sustained delivery of trophic factors in vivo. Hydrogels investigated to date include purely synthetic to purely natural, depending on the application and intended release profiles. Also, flexibility in material processing has allowed for the investigation of injectable materials, the development of scaffolding and porous conduits, and the use of composites for tailored molecule delivery profiles. It is the objective of this review to describe what has been accomplished in this area thus far and to remark on potential future directions in this field. Ultimately, the goal is to engineer optimal biomaterials to deliver molecules in a controlled and dictated manner that can promote regeneration and healing for numerous neural applications.