12-Epi-Napelline regulated TGF-β/BMP signaling pathway mediated by BMSCs paracrine acceleration against osteoarthritis

Background: This study is to investigate the role of 12-Epi-Napelline, a new alkaloid isolated from aconitum, in promoting the paracrine of Bone Mesenchymal Stem Cells (BMSCs) and the synergistic therapeutic effects on osteoarthritis.

Method: We tested the cytotoxicity and optimization of 12-Epi-Napelline, and then simulated the osteoarthritis model in vitro damaging the chondrocytes by lipopolysaccharide (LPS) and RT-qPCR, Western blot and Immunofluorescence were used to detect the inflammatory factor IL-1β, COX-2, TNF-α, MMP-13 and anabolic cytokines of Col-2, BMP-2, TGF-β1 and Sox9 expression in chondrocytes after 12-Epi-Napelline treatment. Under the treatment of different time, Col-2, BMP-2, TGF-β1 and Sox9 expression in BMSCs were detected by RT-qPCR, Western blot, and Immunofluorescence. By establishing an osteoarthritis model in vivo, the anti-osteoarthritis effect of 12-Epi-Napelline or BMSCs was evaluated.

Results: The results showed the expressions of IL-1β, COX-2, TNF-α, and MMP-13 were down-regulated in chondrocytes after 12-Epi-Napelline treatment, while the expression of Col-2, BMP-2, TGF-β1 and Sox9 were increased to normal chondrocytes. These increased expression also occurred in BMSCs. BMSCs had the trend of transforming into chondrocytes by regulating TGF-β signaling pathway under the treatment of 12-Epi-Napelline.

Conclusion: This study could confirm that 12-Epi-Napelline is not only effective in the treatment of osteoarthritis, but also can induce BMSCs to secrete growth factors that promote chondrocyte repair to help repair the damage caused by osteoarthritis.