Melt-Extrusion Additive Manufacturing for Tissue Engineering: Applications and Limitations.

The application of additive manufacturing techniques has increased over the years in almost all production fields, thanks to the possibility of creating objects from scratch and with the desired shape, with no need for molds or complex machinery typical of subtractive manufacturing. This success has concerned the biomedical world as well, where melt-based methods represent the golden standard to produce scaffolds for hard-tissue engineering. Despite the large number of studies present in the literature on scaffold production, the fabrication process is still affected by drawbacks and limitations, which hinders the standardization and upscaling to the industrial level. In this review, we briefly present the history of additive manufacturing and the reasons of its success, with particular reference to the tissue engineering and regenerative medicine world. We then proceed to highlight the current factors limiting the straightforwardness of the production process and affecting the quality and the performance of the manufactured scaffolds. Eventually, we suggest potential strategies to increase the level of control during manufacturing and to improve the biomimicry of the fabricated constructs, with the goal of obtaining a more optimal workflow.