Sacrificial Crystal Templated Hyaluronic Acid Hydrogels As Biomimetic 3D Tissue Scaffolds for Nerve Tissue Regeneration

Pores are key features of natural tissues and the development of tissues scaffolds with biomimetic properties (pore structures and chemical/mechanical properties) offers a route to engineer implantable biomaterials for specific niches in the body. Here we report the use of sacrificial crystals (potassium dihydrogen phosphate or urea) that act as templates to impart pores to hyaluronic acid-based hydrogels. The mechanical properties of the hydrogels were analogous to the nervous system (in the Pascal regime), and we investigated the use of the potassium dihydrogen phosphate crystal-templated hydrogels as scaffolds for neural progenitor cells (NPCs), and the use of urea crystal-templated hydrogels as scaffolds for Schwann cells. For NPCs cultured inside the porous hydrogels, assays for the expression of Nestin are inconclusive, and assays for GFAP and BIII-tubulin expression suggest that the NPCs maintain their undifferentiated phenotype more effectively than the controls (with glial fibrillary acidic protein (GFAP) and Billtubulin expression at ca. 50% relative to the chemically/mechanically equivalent not templated control hydrogels). For Schwann cells cultured within these hydrogels, assays for the expression of S100 protein or Myelin basic protein confirm the expression of both proteins, albeit at lower levels on the templated hydrogels (ca. 50%) than on the chemically/mechanically equivalent not templated control hydrogels. Such sacrificial crystal templated hydrogels represent platforms for biomimetic 3D tissue scaffolds for the nervous system.