Advanced strategies in the application of gelatin-based bioink for extrusion bioprinting

The significance of bioink suitability for the extrusion bioprinting of tissue-like constructs cannot be overemphasized. Gelatin, derived from the hydrolysis of collagen, not only can mimic the extracellular matrix to immensely support cell function, but also is suitable for extrusion under certain conditions. Thus, gelatin has been recognized as a promising bioink for extrusion bioprinting. However, the development of a gelatin-based bioink with satisfactory printability and bioactivity to fabricate complex tissue-like constructs with the desired physicochemical properties and biofunctions for a specific biomedical application is still in its infancy. Therefore, in this review, we aim to comprehensively summarize the state-of-the-art methods of gelatin-based bioink application for extrusion bioprinting. We firstly outline the properties and requirements of gelatin-based bioinks for extrusion bioprinting, highlighting the strategies to overcome their main limitations in terms of printability, structural stability and cell viability. Then, the challenges and prospects are further discussed regarding the development of ideal gelatin-based bioinks for extrusion bioprinting to create complex tissue-like constructs with preferable physicochemical properties and biofunctions. Graphic abstract