TUNABLE PECTIN/COLLAGEN-BASED BIOINKS FOR 3D MODELS OF NEURAL TISSUES

Due to the complexity of the central nervous system and the various pathologies involving this area, many studies are focused on the development of new models to simulate the mechanical, chemical, and physical properties of the nervous tissue. New materials are being explored to develop a suitable hydrogel as a bioink able to embed cells and with the same viscoelastic properties as target tissues, taking advantage of blending, a common choice to create composite materials with the required properties, and 3D printing technology to create complex structures. In this work (funded by Fondazione Cariplo, G.A. 2019-4615. DOI: 10.3389/fbioe.2022.1032542), pectin, an anionic polysaccharide from plant cells, was chosen as a support material due to its capability of crosslinking with CaCO3 by internal gelation to get homogeneous networks. Pectin also presents several bioactive and conductive properties that could be applied to neural tissue engineering. Due to the absence of cell-adhesion sites in pectin, collagen was added to the pectin-based gel. Moreover, this study introduced a new 3D printing approach in which pH is fundamental to determine the viscoelastic properties of the bioink and printing parameters, giving predictable information about the crosslinking speed, printing time, and the final printed structure. Finally, different models of neural cells were embedded in the bioink, obtaining a scaffold that can maintain cell viability and proliferation, without additives or post-printing treatments. The control of pH over viscoelastic properties and printing parameters makes this new bioink an ideal candidate for clinical applications, such as filling up defects by tuning the crosslinking kinetics. Furthermore, our work opens the doors to new cell delivery therapies.