Advancements and Challenges in Tracheal Epithelium Regeneration: Insights into Tissue Engineering Approaches.

Background The trachea, a vital conduit in the lower airway system, can be affected by various disorders, such as tracheal neoplasms and tracheoesophageal fistulas, that often necessitate reconstruction. While short-segment defects can sometimes be addressed with end-to-end anastomosis, larger defects require tracheal reconstruction, a complex procedure with no universally successful replacement strategy. Tissue engineering offers a promising solution for tracheal repair, particularly focusing on regenerating its epithelium, which plays a critical role in protecting the respiratory system and facilitating mucociliary clearance. However, replicating the complex structure and functionality of the tracheal epithelium remains a significant challenge, with key hurdles including proper cell differentiation, functional mucociliary clearance, and addressing the relative lack of vascular supply to the trachea. Summary Current tissue engineering approaches, including biomaterial scaffolds, decellularized tissues, and scaffold-free methods, have shown varying levels of success, while in vitro air-liquid interface (ALI) cultures have provided valuable insights into epithelial modeling. Despite these advances, translating these findings into effective in vivo applications remains difficult due to challenges such as immune responses, inadequate integration with host tissue, and limited longterm functionality of engineered constructs. Overcoming these barriers requires further refinement of cell sources, scaffold materials and bioactive factors that promote vascularization and sustained epithelial function. Key Messages This review evaluates the current strategies and modeling, biomaterial scaffolds, cells, and bioactive factors used in tracheal epithelium regeneration, as well as the methods employed to assess their success through histological, functional, and molecular analyses. While significant progress has been made, the development of a safe, functional, and clinically viable tracheal graft remains elusive, underscoring the need for continued innovation in airway tissue engineering. Future advancements in biomaterial design, stem cell technology, and bioreactor-based tissue maturation hold promise for addressing challenges.