3D Bioprinting of High Cell Density Bioink for Chondrogenic Differentiation in Replacement Tracheal Rings

Tracheal stenosis represents a complex medical challenge due to its debilitating effects on respiratory function. This condition is characterised by the narrowing or obstruction of the tracheal lumen, often resulting from trauma, prolonged intubation, infection, or congenital abnormalities. Severe cases can be life-threatening, significantly impacting the quality of life and leading to respiratory distress. The limitations of existing treatment methods, especially for long-segment tracheal stenosis, mean that novel solutions are required to improve long-term outcomes in such cases. In this study, tissue engineered constructs aiming to mimic the native tracheal tissue's mechanical, structural, and biological properties were fabricated using a high cell density 3D bioprinting system into a support bath of oxidised, methacrylated alginate (OMA) hydrogel. A comprehensive characterisation of various formulations of the hydrogel was conducted to tabulate rheological and mechanical properties, and identify compositions providing a broad range of stiffness supports. Further analysis was then conducted on the constructs to identify the quality of differentiation, maintenance of geometry, and viability of cells when cultured in the different compositions. Future work involving the incorporation of growth factor loaded microparticles within the bioink was also examined in brief in the form of cell aggregates. In order to treat a difficult-to-manage disease state, this study demonstrated the practical application of a novel 3D bioprinting technique, and characterised in greater detail the biomaterials used. These findings help further the application of this high cell density 3D bioprinting technique towards the treatment of tracheal stenosis, and as part of the broader tissue engineering toolkit.