Injectable and self-healing sulfated hyaluronic acid/gelatin hydrogel as dual drug delivery system for circumferential tracheal repair.

Stem cell-based therapies show promise for clinically addressing circumferential tracheal defects (CTD) through tissue engineering. However, creating a tissue-engineered tracheal tube possesses a healthy cartilage matrix and intact tube structure remains a challenge. A solution lies in the use of an injectable hydrogel with shape adaptability and chondrogenic capacity, serving as a practical and dependable platform for tubular tracheal cartilage regeneration. In this study, we developed an injectable hydrogel using modified natural polymers-hydrazide-grafted gelatin (Gelatin-ADH) and aldehyde-modified hyaluronic acid with sulfated groups (HA-CHO-SO) via Schiff Base interaction. Additionally, aldehyde-modified β-cyclodextrin (β-CD-CHO) was introduced into the network during hydrogel formation. The negative sulfated groups and hydrophobic cavities of β-cyclodextrin facilitated the efficient encapsulation and sustained release of transforming growth factor-β1 (TGF-β1) and kartogenin (KGN) within our hydrogel. This synergistically promoted the chondrogenesis of loaded bone marrow stem cells (BMSCs). Subsequently, we employed this TGF-β1, KGN, and BMSCs loaded hydrogel to form a cartilage ring. This ring was then assembled into an engineered tracheal cartilage tube using our previously reported ring-to-tube strategy. Our results demonstrated that the engineered tracheal cartilage tube effectively repaired CTD in a rabbit model. Hence, this study introduces a novel hydrogel with significant clinical application potential for tracheal tissue engineering.