Suppression of MALAT1 promotes human synovial mesenchymal stem cells enhance chondrogenic differentiation and prevent osteoarthritis of the knee in a rat model via regulating miR-212-5p/MyD88 axis.

Osteoarthritis (OA) is one of the most common diseases of the skeleton. Long non-coding RNAs (lncRNAs) are emerging as key players in OA pathogenesis. This work sets out to determine the function of lncRNA MALAT1 in OA and the mechanisms by which it does so. Mesenchymal stem cells isolated from the human synovial membrane are called hSMSCs. The hSMSCs' surface markers were studied using flow cytometry. To determine whether or not hSMSC might differentiate, researchers used a number of different culture settings and labeling techniques. The expression levels of associated genes and proteins were determined using quantitative real-time polymerase chain reaction (RT-qPCR), western blotting (WB), and immunostaining. A dual luciferase reporter experiment and RNA immunoprecipitation (RIP) test demonstrated the direct association between miR-212-5p and MALAT1 or MyD88. MALAT1 was downregulated during the chondrogenic differentiation of hSMSCs, and underexpression of MALAT1 promotes chondrogenesis in hSMSCs. Using dual luciferase reporter and RIP assays facilitated the identification of MALAT1 as a competitive endogenous RNA (ceRNA) that sequesters miR-212-5p. Additionally, the expression of MYD88 was regulated by MALAT1 through direct binding with miR-212-5p. Significantly, the effects of MALAT1 on the chondrogenic differentiation of hSMSCs were counteracted by miR-212-5p/MYD88. Furthermore, our in vivo investigation revealed that the inhibition of MALAT1 mitigated osteoarthritis progression in rat models. In conclusion, the promotion of chondrogenic differentiation in hSMSCs and the protective effect on cartilage tissue in OA can be achieved by suppressing MALAT1, which regulates the miR-212-5p/MyD88 axis.