Tissue Engineered Elastic Cartilage-Mimetic Auricular Grafts for Microtia Reconstruction

Microtia, the congenital malformation of the external ear, imposes a significant psychosocial burden on affected children1-4. The current gold standard treatment, autologous costal cartilage reconstruction, requires multiple complex surgeries, including the harvest of rib cartilage5-7. Tissue engineering offers a promising alternative, enabling the generation of patient-specific auricular grafts from a small biopsy (~5 mg). However, despite multiple decades of research, clinically viable, tissue engineered auricular grafts remain unavailable8. Key challenges include fibrocartilage formation in vitro, heterogeneous extracellular matrix development, and mechanical inferiority, all resulting in graft deformation and degradation in vivo9-15. Here, we report the successful fabrication of bioprinted auricular grafts that closely resemble native human auricular cartilage. Our grafts demonstrated a uniform distribution of elastin, glycosaminoglycans, and collagen II, lacked collagen I, and achieved a compressive modulus of 803 ± 134 kPa after 9 weeks of maturation in vitro (human auricular cartilage: 1023 ± 101 kPa). In vivo, grafts maintained their structural integrity for 6 weeks in a subcutaneous rat model and showed a transition towards mature elastic fiber. These grafts represent the closest approximation to native elastic cartilage reported to date and lay the foundation for a clinically viable, long-term treatment for children affected by microtia.