Development of hyaluronic acid-based scaffolds for brain tissue engineering

Three-dimensional biodegradable porous scaffolds play vital roles in tissue engineering. In this study, a hyaluronic acid-collagen (HA-Coll) sponge with an open porous structure and mechanical behavior comparable to brain tissue was developed. HA-Coll scaffolds with different mixing ratios were prepared by a freeze-drying technique and crosslinked with water-soluble carbodiimide to improve mechanical stability. The pore structure of the samples was evaluated by light and scanning electron microscopy, and the mechanical behavior was analyzed by mechanical compression and tension testing. The degree of crosslinking was determined by the water absorption and trinitrobenzene sulfonic assay, and the HA content was determined by a carbazole assay. The results showed that HA-Coll scaffolds containing an open porous structure with a homogeneous pore size distribution could be fabricated. Certain features of the mechanical properties of HA-Coll scaffolds prepared with a Coll:HA mixing ratio of 1:2, and pure HA sponges, were comparable with brain tissue. Neural stem cells (NSCs) were expanded in number in monolayer culture and then seeded onto the three-dimensional scaffolds in order to investigate the effects of the different types of scaffolds on neurogenic induction of the cells. This study contributes to the understanding of the effects of HA content and crosslink treatment on pore characteristics, and mechanical behavior essential for the design of HA-Coll scaffolds suitable for NSC growth and differentiation for brain tissue engineering.