In vitro and in vivo chondrogenic performance of κ-carrageenan/silk fibroin bioinks containing ADMSCs-seeded microcarriers for auricular cartilage regeneration.

Elastic cartilage is essential for preserving the structural integrity and functional flexibility of tissues such as the auricle and epiglottis. However, its limited capacity for self-repair poses significant challenges in the treatment of injuries resulting from trauma, congenital defects, or disease. This study investigates the in vitro and in vivo regenerative potential of a bioink designed for auricular cartilage repair. The primary polymeric components of the bioink were κ-carrageenan and silk fibroin (κ-CA/SF), while the cellular component consisted of adipose-derived stem cells (ADMSCs) isolated from rabbits, which were subsequently seeded onto poly(butylene adipate-co-terephthalate) (PBAT) microcarriers. These components were successfully printed utilizing an extrusion-based bioprinter. In vitro analyses demonstrated that ADMSCs were effectively encapsulated within the bioink, maintaining their viability for a duration of 21 days. Quantitative RT-qPCR analyses confirmed the expression of COL2A1, the major structural protein of cartilage and a critical indicator of the chondrocyte phenotype; its expression was observed to be approximately 35-fold higher in the κ-CA/SF+PBAT group compared to the κ-CA/SF group (***p < 0.001). Additionally, the presence of collagen II and aggrecan within the constructs was confirmed through immunostaining. For in vivo experiments, a circular defect in auricular cartilage, encompassing the perichondrium on both sides, was created in New Zealand rabbits to facilitate the implantation of tissue scaffolds. Cartilage regeneration was evaluated through histological staining at 4 and 8 weeks post-implantation. In the κ-CA/SF+PBAT group, distinct microcircular structures were identified within the connective tissue, and at later time points, the defect area was predominantly populated with mature cartilage cells, indicating advanced tissue development.