Stem Cell-derived Matrix Enhances Anti-inflammatory Properties Of Articular Chondrocytes Through Activation Of SIRT1

[Objective]:Autologous chondrocyte implantation(ACI)is a promising approach to repair cartilage defects;however,the inflammatory environment of joints compromises clinical outcomes.Stem cell-derived decellularized extracellular matrix(DECM)has been used as a culture substrate for mesenchymal stem cells that improves cell proliferation and lineage-specific differentiation.In this study,we used DECM as an in vitro expansion system for articular chondrocytes and evaluated the response of DECM-expanded chondrocytes to an inflammatory environment induced by interleukin-1β(IL-1β)or tumor necrosis factor-α(TNF-α).[Methods]:We treated the knee joint articular chondrocytes of New Zealand white rabbits using decellularized extracellular matrix(DECM)and conventional tissue culture polystyrene(TCPS).The cell proliferation ability was measured by the CCK-8 method and photographed.The synthesis of cartilage matrix and the expression of related genes were determined by culturing high-density pellet cultures made of chondrocytes expanded with DECM and TCPS in chondrogenic medium.High-density cell pellets produced by chondrocytes proliferating from DECM and TCPS were cultured by adding IL-1β or TNF-a into chondrogenic medium throughout the whole time.To compare the ability of both to protect chondrocytes to form a specific cartilage matrix in an inflammatory environment.Chondrocyte pellets were treated with IL-1β or TNF-α for 7 days to evaluate pro-inflammatory cytokine-induced cartilage degradation.Finally,the role of the SIRT1 gene is demonstrated by the use of the SIRT1 inhibitor NAM.[Results]:Compared with chondrocytes grown on conventional tissue culture polystyrene(TCPS),the cell proliferation rate was significantly higher in DECM-expanded cells.Chondrocytes were induced to chondrogenic differentiation in high-density pellet cultures,and both groups showed comparable chondrogenic potentials.When exposed to IL-1β or TNF-a at a low concentration(1 ng/mL)for 21 days,DECM-expanded chondrocytes showed higher levels of cartilage matrix synthesis than those from the TCPS group;however,a high concentration(5 ng/mL)of IL-1β inhibited differentiation in both groups.Chondrocyte pellets were treated with IL-1β or TNF-α for 7 days,and we found that gene expression of matrix degradation-related enzymes was significantly lower in DECM-expanded chondrocytes than those cultured on TCPS.We also found that SIRT1 inhibition by nicotinamide completely counteracted the protective effect of DECM on chondrocytes in the presence of IL-1β or TNF-α,indicative of activation of the SIRT1 signaling pathway in chondrocytes.[Conclusion]:Taken together,this work suggests that stem cell-derived DECM is a superior culture substrate for in vitro chondrocyte expansion as it improves resistance to an arthritic inflammatory environment.Stem cell-derived DECM holds great potential in clinically ACI-based cartilage tissue engineering.