BACKGROUND:Trauma,inflammation,tumors,and other factors commonly result in tissue defects,including damage to bones,joints,skeletal muscles,and associated blood vessels and nerves.Clinically,it is often challenging to repair all the functional injuries involving these tissues,posing great challenges for clinical treatment. OBJECTIVE:To elucidate the application of 3D-printed hydrogel biomimetic structures in motor system tissue injuries. METHODS:Relevant literature published from 2003 to 2023 was retrieved from the CNKI,Wanfang Data,and PubMed databases.The Chinese and English search terms were"3D printing,hydrogel,bone,cartilage,muscle,nerve,vasculature,tissue engineering,biomimetics".After screening,induction and summary,63 relevant articles were finally included for review. RESULTS AND CONCLUSION:(1)3D-printed hydrogels can be achieved in several different ways,such as direct 3D printing,hybrid mode 3D printing,or manufacturing 3D bio-inspired structures in hydrogels by printing intermediate molds.Among these manufacturing processes,extrusion-based printing is currently the most widely used for 3D printing hydrogels with bio-inspired structures.(2)Bioprinting hydrogels enables the production of biovascular structures with complex perfusion patterns,and it can induce the formation of biologically relevant,highly organized,and intact blood vessels.(3)By utilizing bioprinting technology,it is possible to mimic the hierarchical structure and function of natural bone,combining hydrogels with different types of cells and growth factors to create tissue engineering scaffolds that closely resemble the composition and structure of natural bone,thereby facilitating better bone regeneration.(4)Neural fiber structure can be bio-inspired by incorporating different fiber materials into the 3D-printed hydrogel conduit structure.(5)Utilizing specific hydrogel formulations,it is possible to simulate muscle bundle structures or engineer muscle tissues integrating blood vessels and nerves,which can enhance the repair of volumetric muscle injuries in vivo.(6)Based on current related research,methacrylated gelatin,which closely resembles the characteristics of the extracellular matrix,is often considered as a raw material for 3D printing various tissue bio-inspired structures.Researchers also incorporate different growth factors or cells into the hydrogels for bioprinting to achieve the desired tissue repair outcomes.(7)Although there is a lack of clinical trial reports on 3D-printed hydrogel bio-inspired structures,this indicates that the clinical translation of such materials still requires a long-term process.Further improvements are needed in terms of clinical applications,as well as comprehensive in vivo safety assessments.