Effects of Biodegradable Polymers on the Rat's Damaged Spinal Cord Neural Membranes

     The overall goal of this study was to identify the appropriate biomaterials able to facilitate the regeneration in rat's injured adult spinal cord. Acute damage to axons is manifested as a breach in their membranes, ionexchange distortion across the compromised region, local depolarization and even conduction block. It would be of particular importance to interrupt the progress of events happening after acute injury to the spinal cord. Repair strategies using transplants of cells have shown many attractions in spinal cord repair studies. However, as the processes of purification and growth require time, they cannot be fully implemented in acute injuries. Furthermore, application of cell grafts from other human or animal sources are likely to provoke immune reactions in human patients. Immediate repairing or sealing the regions of compromised membrane with hydrophilic polymers or surfactants could retard or reverse the permeabilization of nerve fiber membranes. Biodegradable polymeric materials used for tissue engineering, made of either peptide or non-peptide components, are considered as potential candidates. Application of the hydrophilic polymer, polyethylene glycol (PEG), has showed to be effective in the repair of nerve membrane damage associated with severe spinal cord injury in adult rat. This class of large hydrophilic molecules can reverse the permeabilization of ruptured cell membranes as well as anatomically reconnect their severed processes. Our preliminary results showed rather rapid partial restoration of the declined magnitude of compound actions potentials (CAPs) in injured spinal cords, varying as a result of the introduction of PEG's with different molecular weights.