Chapter 12. 3D Bioprinting Hydrogel for Hard Tissue Regeneration

Hard tissue defects have always been a major problem in clinical practices that plague humans because of population aging or injury. In the meantime, 3D bioprinting has increasingly gained tremendous progresses over the past decade in the field of biomedical engineering because of the ability to fabricate rapidly individualized tissue constructs and precise geometry designability. With the development of solvent-free, water-based systems, biomaterials, especially hydrogel-based bioink, could be directly bioprinted into scaffolds or tissue constructs utilizing 3D bioprinting, and cells could be cultivated and proliferated on the bioprinted scaffolds, further for the subsequent transplantation in clinical practice. And, the foremost biocompatible materials employed in existing 3D bioprinting method are hydrogels, which could be laden with different cell types and easily synthesized from natural polymers. In this chapter, the properties, structures and applications of 3D bioprinted hydrogel scaffolds for hard tissue including cartilage and bone are reviewed in conjunction with recent advances. And the current limitations such as low mechanical properties, poor stabilities and printability are presented, as well as the corresponding improved methods. We finally conclude with prospects about 3D bioprinting in hard tissue regeneration.