Scaffold-free Tracheal Engineering via a Modular Strategy Based on Cartilage and Epithelium Sheets.

Tracheal defects lead to devastating problems, and practical clinical substitutes that have complex functional structures and can avoid adverse influences from exogenous bioscaffolds are lacking. Herein, a modular strategy for scaffold-free tracheal engineering was developed. A cartilage sheet (Cart-S) prepared by high-density culture was laminated and reshaped to construct a cartilage tube as the main load-bearing structure in which the chondrocytes exhibited a stable phenotype and secreted considerable cartilage-specific matrix, presenting a native-like grid arrangement. To further build a tracheal epithelial barrier, a temperature-sensitive technique was used to construct the monolayer epithelium sheet (Epi-S), in which the airway epithelial cells presented integrated tight junctions, good transepithelial electrical resistance, and favorable ciliary differentiation capability. Epi-S could be integrally transferred to inner wall of cartilage tube, forming a scaffold-free complex tracheal substitute (SC-trachea). Interestingly, when Epi-S was attached to the cartilage surface, epithelium-specific gene expression was significantly enhanced. SC-trachea established abundant blood supply via heterotopic vascularization and then was pedicle transplanted for tracheal reconstruction, achieving 83.3% survival outcomes in rabbit models. Notably, the scaffold-free engineered trachea simultaneously satisfied sufficient mechanical properties and barrier function due to its matrix-rich cartilage structure and well-differentiated ciliated epithelium, demonstrating great clinical potential for long-segmental tracheal reconstruction. This article is protected by copyright. All rights reserved.