Injectable multifunctional scaffold for spinal cord repair

Spinal cord injury (SCI) affects thousands of Americans each year. The injury results in local cell loss in the spinal cord, interrupting the connections between brain and periphery. Current treatment options for SCI are limited due to the inability of adult neurons to regenerate in the inhibitory environment of the injured central nervous system (CNS). The primary goal of this work is to design a multifunctional, injectable hydrogel that supports neural repair following SCI. This project proposes the use of a branched copolymer based on poly(N-isopropylacryalmide) (PNIPAAm) and poly(ethylene glycol) (PEG). The thermosensitive nature of the hydrogel allows for easy implantation together with cellular grafts, and the controlled delivery of therapeutic factors. In this study, we investigated the cytocompatibility of the scaffold in vitro and also report its performance in vivo, with and without brain derived neurotrophic factor (BDNF) in a rodent model of SCI. Our results show that the injectable PNIPAAm-PEG scaffold completely fills the injury site, and does not elicit a larger host inflammatory response than a commercially available gelatin sponge. In addition, we have shown that the scaffold loaded with BDNF is permissive to host axon growth. With these promising results, we suggest that an injectable PNIPAAm-PEG hydrogel can serve as a multifunctional device that will result in an effective platform technology for the treatment of SCI.