Design and fabrication of scaffold-based tissue engineering

Scaffold-based tissue engineering approaches have been under investigation for more than 30 years now and many different techniques have been developed in order to engineer various tissues of the body. Some of them have been translated from bench to bedside, yet many are still under intensive examination. Biodegradable scaffolds applied in tissue engineering aim to temporarily substitute for the extracellular matrix and its complex biological functions during the regeneration and/or remodelling period, and are subsequently degraded and replaced by new tissue. We herein discuss how knowledge from developmental biology and collective tissue healing biology can be applied to optimise the design of scaffolds that promote fundamental steps in tissue regeneration by creating a suitable microenvironment. The review focuses on the design and fabrication of scaffolds for bone tissue engineering, yet also highlights general considerations which apply to scaffolds used in any tissue engineering strategy. We then turn to scaffold manufacturing where a plethora of design and fabrication technologies have been applied to process biomaterials into scaffolds for bone tissue engineering and other applications. Each manufacturing technology has its advantages and disadvantages from a processing, material science and biological point of view. We herein review several additive manufacturing technologies, which in the authors' opinion currently are most relevant for scaffold-based bone tissue engineering. We also provide a future outlook on Image-guided Tissue Engineering, Additive Tissue Manufacturing and Guided Tissue Regeneration with respect to tissue engineering in general and bone tissue engineering in particular.