〔Abstract〕 Objective To study the protective effect of mesenchymal stem cells(iPSC-MSCs) derived from pluripotent induced stem cells on the articular cartilage tissue of patients with knee osteoarthritis(KOA) in vitro and its partial mechanism.Methods With informed consent, the articular cartilage of KOA patients was collected, shredded and treated with IL-1β(10 ng/ml) to stimulate 96 h, and then different numbers of iPSC-MSCs(1 × 104, 1 ×105, 1 × 106) cells were added and cultured for 3 d in a 37 ℃, 5% CO2incubator. In addition, IL-1β(10 ng/ml) induction group and culture medium control group were set up. Chondroitin sulfate assay method was used to detect glycosaminoglycan content in cartilage tissue, immunohistochemical method was used to detect the expression of type Ⅰ collagen and type Ⅱ collagen in the tissue, and ELISA method was used to detect the level of MMP13,IL-6 and IL-10 in the co-culture supernatant, HE staining was used to detect the pathological changes of cartilage tissuein vitro.Results Compared with the control group, IL-1β could induce swelling and death of chondrocytes in the cartilage tissue of KOA, increase the proportion of inflammatory cells, increase the level of type I collagen,decrease the level of type Ⅱ collagen, and the level of MMP-13 and IL-6 in the culture supernatant significantly increased(P<0. 05), and the content of IL-10 and glycosaminoglycan was significantly reduced(P<0. 05); compared with the IL-1β induction group, the co-culture of iPSC-MSCs with different cell numbers could reduce the MMP-13, IL-6 level and type I collagen level in the supernatant, promote the expression of type Ⅱ collagen, increase glycosaminoglycan content and IL-10 level in cartilage tissue.Conclusion iPSC-MSCs can regulate the level of inflammatory factorsin vitro, inhibit the degradation of chondrocyte matrix, and have a protective effect on articular cartilage tissue.