Clinically adaptable size cartilage grafts generated from human embryonic stem cells enable tracheal repair in a porcine model

Autologous costal cartilage grafting is commonly used for pediatric tracheal reconstruction; however, it has several limitations, including restricted availability and surgical invasiveness. In this study, we investigated the feasibility of a novel tracheal reconstruction approach using human embryonic stem cell–derived cartilage tissue (ESCaT). ESCaT was differentiated from human embryonic stem cells (SEES2), and large-scale cartilage constructs were generated by integrating tissues derived from multiple culture dishes within a nylon mesh scaffold. Decellularized ESCaT (dESCaT) was subsequently produced using a high hydrostatic pressure method. These constructs were transplanted into a porcine tracheal defect model, and airway patency, histological changes, and immune responses were evaluated. In addition, similar analyses were performed in operational immunodeficient pigs (OIDPs) treated with immunosuppressive regimens. ESCaT was reproducibly generated as plate-shaped constructs with an average size of 18.2 × 14.2 × 4.4 mm, exhibiting sufficient mechanical strength to withstand suturing and airway pressure. In non-treated pigs, both ESCaT and dESCaT induced strong inflammatory responses after transplantation, resulting in loss or replacement of cartilage tissue. In contrast, in the OIDP model, dESCaT grafts were maintained, and airway patency ranged from 84.7% to 100.8%. Histological analysis revealed only mild inflammatory cell infiltration, along with evidence of epithelial regeneration. ESCaT demonstrates clinically relevant size and mechanical strength, indicating its potential as a graft material for tracheal reconstruction. However, immune responses in xenogeneic transplantation remain a major challenge, and the combination of decellularization and immunomodulation is critical for graft survival. Further studies are required to reduce immunogenicity and optimize tissue maturation for future clinical applications.