**5. Conclusions**

In the last decade, two groundbreaking discoveries, i.e., somatic cell reprogramming into iPSCs and 3D bioprinting, changed the way to modeling diseases, in particular for those pathologies which are hard to study in simple cell cultures, such as neurodegenerative diseases. The first one is permitted to obtain neural cell cultures in few months starting from adult somatic cells, like fibroblasts and PBMCs, while 3D bioprinting consists in the print of hydrogel and cells, to generate models that imitate tissue characteristics. While iPSCs are differentiated into neurons in many papers for disease modeling, 3D bioprinting is actually used for few tissues, like the cartilage, bone, and heart. Neural 3D cell cultures are still in development, there are no target bioinks, and the studies that combine neuronal cells and 3D bioprinting are more complicated than other tissues because of the fragility of such cells. Despite this hurdle, the possibility to create an in vitro neural tissue would open many fields of research that today are unreachable, first of all the opportunity to study the 3D spatial connection between different neuronal populations and how they communicate with each other. In combination with iPSC technology, we can create a physiological model to understand physiological and pathological mechanisms and to better understand mechanisms underlying neurodegenerative diseases.

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Finally, the combination between 3D bioprinting and iPSC technology will open not only new possibilities in many fields, drug screening, replacing expensive in vivo experiments, and overcoming animal models' issues, but also personalized medicine thanks to the use of cells derived from patients. More intriguingly, the generation of a 3D neural tissue composed of patient's cell will allow the so-called neuro-regeneration, opening the possibility to replace a degenerated tissue.
