Tissue-engineered soft tissue oriented manufacturing technologies and additive manufacturing

Background: In recent years, many manufacturing techniques have been recently developed for soft tissue engineering scaffolds. Especially additive manufacturing with a unique material accumulated forming principle can be feasible and reliable to manufacture the highly precise scaffolds with gradient structures and multi-materials for large soft tissue defect repairing. Objective: To summarize scaffolds manufacturing technologies in the soft tissue engineering applications developed in recent years and to predict the direction of development. Methods: A retrieval was performed for the literature about the manufacturing methods of soft tissue scaffolds using key words of "additive manufacturing, microfabrication, vascular tissue engineering, muscle tissue engineering, cartilage tissue engineering, stereolithography, 3D printing, biodegradable hydrogel" in English and Chinese, which were published between January 2010 and September 2013 in PubMed Database and China National Knowledge Infrastructure (CNKI) Database. Results And Conclusion: For large soft tissue defects repairing, structure design of the scaffolds has been shifted from a simple planar structure to a more complex three-dimensional structure, and integration of scaffold structure, materials and cells, and growth factors during the manufacturing procedure can be used to obtain the resolution of vascularization. Additive manufacturings become one of the most promising approaches for the ideal soft tissue scaffolds with gradient and complex structure and multi-materials. In particular, the hydrogel/cell composite scaffolds fabrication, a hot but promising approach to develop the soft tissue engineering will be made progress by the accurate principles and processes of the hydrogel additive manufacturing combined with the introduction of living cells and growth factors.