Structurally anisotropic hydrogels for tissue engineering

Many tissues in vivo exhibit structural anisotropy, which endows them with orientation-specific properties and functions. Structurally anisotropic hydrogels have emerged as promising scaffolds for tissue engineering applications, owing to their ability to recapitulate the structure and physical properties of anisotropic tissues in vivo and provide cells with the appropriate cues. This review highlights key progress in the development of biocompatible structurally anisotropic hydrogels for tissue engineering. We provide an overview of tissues with structural anisotropy and different fabrication methods of anisotropic hydrogels, summarize different characterization methods of hydrogel structural anisotropy, and provide insights on the physical properties of anisotropic hydrogels and their impact on cell behavior. We conclude with a critical assessment of future directions of structurally anisotropic hydrogels for tissue engineering applications.