Role of integrin b1 and tenascin C mediate TGF-SMAD2/3 signaling in chondrogenic differentiation of BMSCs induced by type I collagen hydrogel

Cartilage defects may lead to severe degenerative joint diseases.Tissue engineering based on type I collagen hydrogel that has chondrogenic potential is ideal for cartilage repair.However,the underlying mechanisms of chondrogenic differentiation driven by type I collagen hydrogel have not been fully clarified.Herein,we explored potential collagen receptors and chondrogenic signaling pathways through bioinformatical analysis to investigate the mechanism of collagen-induced chondrogenesis.Results showed that the super enhancer-related genes induced by collagen hydrogel were significantly enriched in the TGF-b signaling pathway,and integrin-b1(ITGB1),a receptor of collagen,was highly expressed in bone marrow mesenchymal stem cells(BMSCs).Further analysis showed genes such as COL2A1 and Tenascin C(TNC)that interacted with ITGB1 were significantly enriched in extracellular matrix(ECM)structural constituents in the chondrogenic induction group.Knockdown of ITGB1 led to the downregulation of cartilage-specific genes(SOX9,ACAN,COL2A1),SMAD2 and TNC,as well as the downregulation of phosphorylation of SMAD2/3.Knockdown of TNC also resulted in the decrease of cartilage markers,ITGB1 and the SMAD2/3 phosphorylation but overexpression of TNC showed the opposite trend.Finally,in vitro and in vivo experiments confirmed the involvement of ITGB1 and TNC in collagen-mediated chondrogenic differentiation and cartilage regeneration.In summary,we demonstrated that ITGB1 was a crucial receptor for chondrogenic differentiation of BMSCs induced by collagen hydrogel.It can activate TGF-SMAD2/3 signaling,followed by impacting TNC expression,which in turn promotes the interaction of ITGB1 and TGF-SMAD2/3 signaling to enhance chondrogenesis.These may provide concernful support for cartilage tissue engineering and biomaterials development.