Indirect Rapid Prototyping for Tissue Engineering

Tissue engineering (TE) aims at producing patient-specific bio- logical substitutes in an attempt to repair, replace and regener- ate damaged tissues or organs in order to improve the current state of clinical treatments. A three-dimensional substrate, the scaffold, is a key aspect to promote cell organization to form a tissue. Recently, rapid prototyping (RP) technologies have been successfully used to fabricate complex scaffolds, thanks to the ability to create highly reproducible architecture and composi- tional variation across the entire structure, due to their precise controlled computer driven fabrication. The drawback of most of the fabrication principles applied in the RP processes is the requirement of particular conditions (e.g., pressure or tempera- ture) that limit the material choice. Natural polymers, such as collagen, have underlined their superiority for TE solutions but they are challenging to be processed with RP techniques. As al- ternative, scaffold made of natural biomaterial can be produced by indirect fabrication techniques, casting a biomaterial into sacrificial mold realized by RP processes. So far, the indirect rapid prototyping (iRP) has emerged in a number of different ap- proaches with promising results. The present chapter is focused on iRP multistep methods, highlighting strength and weakness and indicating possible future perspectives.