Hydrogel Biomaterial in Bone Tissue Engineering

The repair of critical-sized bone defect caused by trauma or disease poses a remarkable clinical challenge. Even though conventional methods such as autografts and allografts have been commonly used, they each have corresponding shortcomings limiting their clinical application. Generally, existing biomaterials such as metals and cements cannot meet the clinical needs. Therefore, there is a critical need for the development of biomimetic and bioactive three-dimensional (3D) scaffolds for bone regeneration. The use of hydrogels is considered a promising strategy in bone tissue engineering due to their highly aqueous 3D network structure and functional characteristics. This chapter focuses on use of natural and synthetic hydrogel scaffolds inspired by extracellular matrix (ECM) biology and structure for bone tissue engineering. Firstly, we discuss the requirements of hydrogel substitutes, the type of hydrogels used and their properties, as well as the combination of hydrogels with growth factors, cells, drugs, and inorganic components. Afterwards, current fabrication strategies are presented, with the emphasis on the implantable hydrogels and injectable hydrogels. Finally, the current challenges, considerations, and future directions are discussed in order to provide new directions for the design and clinical use of hydrogel scaffolds in bone regeneration. We believe that recent advances in the multifunctional bioactive hydrogels offer important information to researchers in the field and clinicians to generate new perspectives on bone repair.