(489j) In Vivo Analysis of Pnipaam-PEG, An Injectable Scaffold for Spinal Cord Repair

Spinal cord injury affects thousands of Americans each year. These injuries are typically life altering, due to the death of nervous tissue in the spinal cord, which creates a void where the electrochemical signal can no longer pass. Current treatment options for such injuries are limited, due to the body's inability to regenerate neurons and the difficulty in stabilizing the defect created by the injury. This project proposes the use of a non-biodegradable hydrogel as a mechanical support to fill the injury site and provide a protected environment for the regenerating neurons. A multifunctional tissue-engineering scaffold will be used that supports neuronal regeneration following spinal cord injury. The scaffold will have mechanical properties similar to the host tissue and allows easy implantation. It will also have the ability to support host axon growth as well as survival of cells seeded into the matrix. The scaffold also will allow for the gradual release of bioactive therapeutic factors. The thermally responsive, injectable polymer that will be used is a PNIPAAm-PEG branched copolymer. It allows for a minimally invasive surgical technique. The scaffold does not result in further damage to the injured spinal cord upon implantation. Goals of this work include characterization of the material properties of the injectable scaffold in vitro and in an in vivo rodent model. Work is also being completed to determine the bioactivity and release rate of neurotrophins from the drug-loaded scaffold to determine the dose-response relationships and optimal doses using in vitro biological assays.