Daniela P Pacheco and Paola Petrini
Polytechnic University of Milan, Italy
Posters & Accepted Abstracts: J Material Sci Eng
Three-dimensional bioprinting is the process of extruding cells with or without the addition of materials in a precise spatial arrangement towards tissue substitutes. Yet bioprinting bears some limitations, mainly the selection of materials to be used as bioinks. Among others, bioinks must be able to mimic native tissue microenvironment and protect cells from the shear-stress to which they are submitted during printing process, without compromising the resolution, shape and stability of the tissue construct. These features are common for injectable hydrogels, which are 3D hydrophilic networks that facilitate oxygen, nutrients and growth factors diffusion and partially mimic tissue physical characteristics. Some examples of natural-derived materials include decellularized tissue, gelatin, fibrin, collagen and alginate. Nevertheless, the gelification kinetic of current proposed bioinks is impairing the printability of tissue constructs. Pectin can be considered a novel and versatile biomaterial as its favorable properties, including swelling, degradation, cell immobilization, and binding or release of bioactive molecules can be tailored by the crosslinking mechanisms and agent. Herein, an innovative injectable pectin hydrogel encapsulating human adipose stem cells is proposed. Gelation kinetics, viscosity and shear-thinning properties could be finely tailored by controlling pH, pectin concentration and gelifying methods. Gelification time of the developed hydrogels ranged from seconds to 20 minutes, accordingly with the adopted conditions, therefore offering a suitable time window to prevent the collapse of the gel post-printing. Additionally, the obtained viscosity is within the range of the different bioprinting techniques, namely inkjet, orifice-free and extrusion. Their injectable potential was confirmed through rheological analyses. Upon extrusion through 20G and 25G needles, cells encapsulated within pectin hydrogels were viable and kept their stemness capability up to 7 days after extrusion, indicating that the presence of 3D pectin hydrogels protects cells from damaging during the printing process. In this sense, a ready-to-use and inexpensive pectin hydrogel is herein proposed as a bioink for 3D bioprinting tissues.