Influence of synthesis parameters on hyaluronic acid hydrogels intended as nerve conduits

Hydrogels have widely been proposed lately as strategies for neural tissue regeneration, but there are still some issues to be solved before their efficient use in tissue engineering of trauma, stroke or the idiopathic degeneration of the nervous system. In a previous work of the authors a novel Schwann-cell structure with the shape of a hollow cylinder was obtained using a three-dimensional conduit based in crosslinked hyaluronic acid as template. This original engineered tissue of tightly joined Schwann cells obtained in a conduit lumen having 400 μm in diameter is a consequence of specific cell-material interactions. In the present work we analyze the influence of the hydrogel concentration and of the drying process on the physicochemical and biological performance of the resulting tubular scaffolds, and prove that the cylinder-like cell sheath obtains also in scaffolds of a larger inner diameter. The diffusion of glucose and of the protein BSA through the scaffolds is studied and characterized, as well as the enzymatic degradation kinetics of the lyophilized conduits. This can be modulated from a couple of weeks to several months by varying the concentration of hyaluronic acid in the starting solution. These findings allow to improve the performance of hyaluronan intended for neural conduits, and open the way to scaffolds with tunable degradation rate adapted to the site and severity of the injury.