Biostampa 3D di costrutti cellularizzati in vitro

Nowadays, developing new in vitro models is becoming crucial to better mimic the physiological microenvironment and recapitulate the macroscopic architecture of the desired tissues. To achieve the former, refined materials are essential, since their internal structure can have a profound impact on encapsulated cells behavior; to achieve the latter, always more sophisticated engineering techniques are pivotal to pattern materials exactly as it is needed. 3D bioprinting has risen as one of the most promising techniques to manufacture in vitro tissues: while it requires a very fine setting of several parameters, it has paved the way to the creation of thick cell-laden constructs. Howbeit, with thickness comes a new hurdle: the need to provide nutrients to the cells in the bulk. The aims of my work were the study and characterize materials to then design and fabricate thick in vitro constructs to better mimic cancer tissue. To tackle the problem of sustaining cell viability in the bulk of the material, two approaches were followed: the development of a bioprintable material with enhanced internal porosity, and the design and fabrication of vascularized constructs using bioprinting methods crafted ad hoc. The material developed in this study achieved a peculiar internal pore distribution, with both microscale and mesoscale pores (tens of μm and hundreds of μm in diameter, respectively). Its increased porosity can facilitate nutrients delivery and allow for cells reorganization, while its printability with extrusion bioprinting proved it can effectively be used to create precise geometries. Fabricating vascularized constructs required well-crafted protocols to yield 3D cancer models with perfusable, endothelialized, channels. Perfusability, capacity to sustain cell viability in the whole construct, and endothelialization of the channels were all investigated to assess the versatility and robustness of the protocols, which proved effective in creating constructs with both planar and branched vascular networks. The obtained results demonstrate the in-depth control over extrusion bioprinting that was achieved, granting the ability to modify the designs and pattern geometries easily and flexibly. Furthermore, they highlight the important role that bioengineers have in creating more physiologically relevant in vitro model to push research forward.