Promotion of bone morphogenetic protein 9-induced mesenchymal stem cell osteogenesis by transforming growth factor-?茁1

Abstract:

Objective：To investigate the effect of transforming growth factor-β1（TGF-β1） on bone morphogenetic protein 9（BMP9）-induced mesenchymal stem cells（MSCs） osteogenic differentiation. Methods：C3H10T1/2 cell line infected with BMP9 adenovirus and added with TGF-β1 protein was used to create the osteogenic model. The modified SEAP chemoluminescence assay was used for al－kaline phosphatase（ALP） activity. Alizarin red staining was used for mineralization. Real-time PCR and immunocytochemistry were used for bone markers collagen typeⅠa2（COLⅠa2），osteopotin（OPN） and osteocalcin（OCN）. Luciferase reporter assay was used for detecting the Smad expression. Results：BMP9 combined with TGF-β1 induced more ALP activities and mineralization（F=18 782.10，P=0.000） than single BMP9. However，there was no difference between single TGF-β1 group and single GFP group after treating con－secutively for 17 d（F=1.03，P=0.318）. mRNA expression of OPN，OCN and COLⅠa2 was increased in BMP9 combined with TGF-β1 group than in single BMP9 group（FCOLⅠa2=250.30，P=0.000；FOPN=795.64，P=0.000；FOCN=206.55，P=0.000）. BMP9 combined with TGF-β1 increased COLⅠa2 more significantly at earlier stage（F=250.30，P=0.000） and increased the protein expression of OPN and OCN in vitro. BMP9 combined with TGF-β1 stimulated the activity of luciferase reporter of related Smads（?字2=32.84，P=0.000）. Conclu－sions：TGF-β1 promotes BMP9-induced osteogenic differentia－tion in MSCs. TGF-β1 and BMP9 might have synergistic effects.