Evaluation of thermoresponsive biopolymers-based composite bioinks for cartilage engineering

• Carboxylated agarose (CA) and gelatin-A blends (CAGelA) form homogenous blends, that show shear-thinning and can be extrusion printed. • CAGelA printed constructs are mechanically robust and can be handled. • CAGelA supports the printing of high volumetric density of human septum-derive chondrocytes (hNCs). • Gel-A functions as a porogen and promotes cell distribution. • CAGelA printed constructs support chondrogenesis in hNCs and promote extracellular matrix deposition. Due to the low regenerative capacity of damaged cartilage, strategies to promote cartilage repair remain an evolving but unmet clinical need. 3D bioprinting (3DBP) offers a way to refine the principles of tissue engineering and generate bespoke cell-laden constructs better aligned with the biological aspects of the cartilage trauma and the anatomical site. Therefore, bioinks that possess attributes for extrusion-printing and support the cartilage matrix deposition are essential. In this study, bioinks comprising a double network of thermogelling biopolymers, namely carboxylated agarose and gelatin, were developed and characterized extensively for their rheological properties and printability. Formulations that combine printability and printed object stability were identified using an optimization strategy, and their ability to support matrix production in human nasal chondrocytes (hNCs) was investigated. In general, printed constructs with lower solid content favored ECM deposition, and the incorporation of gelatin improved hNCs distribution, homogeneity of type-II collagen expression, and biosynthesis of glycosaminoglycans. These findings offer valuable insights into the development of bioinks that can be translated into practical applications for cartilage engineering.