The feasibility of human embryonic stem cell (hESC)-derived cartilage for tracheoplasty

Introduction: Airway reconstruction with autologous costal cartilage often results in long-term complications. On the other hand, implant-type regenerated cartilage using chondrocytes and scaffolds is associated with better biocompatibility and outcomes. Nevertheless, obtaining a substantial amount of chondrocytes remains a challenge. Allogenic cartilage from human embryonic stem cells (hESCs) can be used as an alternative graft for tracheal reconstruction. The aim of this study was to determine the regenerative potential of hESCs-derived cartilage tissue. Methods: The clinical grade hESC line sSEES-2 was cultured in chondrocyte differentiation media for eight weeks. Maturation potential was estimated by subcutaneous transplantation into immunodeficient mice and the mechanical properties were measured with a tactile sensor. For tracheoplasty studies, the matured cartilage constructs were implanted into tracheotomized sites in athymic rats, and were evaluated 1- and 3-months post-implantation through endoscopy and histological analysis. Results: Small cartilage tissues – or “cartilage islets” – were successfully obtained by culturing the SEES2 cells in specialized media. The thickness and strength (Young's modulus) of the grafted cartilage increased one month after implantation, indicating maturation. Furthermore, the cartilage graft successfully restored artificial defects in rat trachea with no structural damage or air leakage. The tracheal mucosa recovered one month after the implantation, and airway patency was maintained for three months. Histological analysis of the tracheal tissues revealed epithelial regeneration, and direct integration between the cartilage graft and native cartilage without the formation of granulation tissue. Conclusions: Cartilage tissue derived from hESCs successfully maintained airway structure and biocompatibility in a rat model for three months, which supports the application of engineered cartilage for clinical airway reconstruction.