Kartogenin preconditioning commits mesenchymal stem cells to a precartilaginous stage with enhanced chondrogenic potential by modulating JNK and β-catenin−related pathways

Cartilage engineering strategies using mesenchymal stem cells (MSCs) could provide preferable solutions to resolve long-segment tracheal defects. However, the drawbacks of widely used chondrogenic protocols containing TGF-β3, such as inefficiency and unstable cellular phenotype, are problematic. In our research, to optimize the chondrogenic differentiation of human umbilical cord MSCs (hUCMSCs), kartogenin (KGN) preconditioning was performed prior to TGF-β3 induction. hUCMSCs were preconditioned with 1 μM of KGN for 3 d, sequentially pelleted, and incubated with TGF-β3 for 28 d. Then, the expression of chondrogenesis- and ossification-related genes was evaluated by immunohistochemistry and RT-PCR. The underlying mechanism governing the beneficial effects of KGN preconditioning was explored by phosphorylated kinase screening and validated in vitro and in vivo using JNK inhibitor (SP600125) and β-catenin activator (SKL2001). After KGN preconditioning, expression of fibroblast growth factor receptor 3, a mar...