Hierarchical hydrogel scaffolds with a clustered and oriented structure.

Hydrogel scaffolds play a critical role in tissue engineering due to their hydrophilic network structure and good biocompatibility. Constructing anisotropic scaffolds geometrically similar to injured tissues is conducive to promoting the generation of tissue and organ equivalents, or to guiding and enhancing the regeneration of injured tissues. In this study, we developed polyvinyl alcohol (PVA)/alginate hierarchical hydrogel scaffolds with a clustered and oriented structure using a method that combines directional freezing and drying under stretching. Our hydrogel scaffolds with an adjustable modulus (50 kPa-20 MPa) can match different types of injured tissues. The clustered and oriented structure successfully guided the alignment and orientation of fibroblasts and chondrocytes. This work provides a new idea for constructing hydrogels with hierarchical and anisotropic microstructures, which have promising applications in tissue regeneration.