Suppression Of Runx2 Potentiates BMP2-induced Chondrogenic Differentiation And Inhibits BMP2-induced Osteogenic Differentiation

Objective: To investigate the potentiation effect of RNA silenced Runx2 on bone morphogenetic protein 2(BMP2) induced chondrogenic differentiation and osteogenic differentiation of mesenchymal stem cells(MSCs).Method: C3H10T1/2 cells were treated with adenovirus: Ad-BMP2,Ad-SiRunx2 or Ad-GFP. The sulfated glycosaminoglycan of cellular matrix was detected by Alcian Blue Staining. The early osteogenic marker ALP activity was detected by quantitative chemiluminiscence assay. The later osteogenic marker calcium deposition was detected by Alizarin Red S staining.The mRNA level of Runx2, Col2a1, aggrecan, Col10a1,ALP and Col1a1 were detected by RT-PCR,and the protein level of BMP2, Col2a1,Col10a1 and OCN were detected by Western blot.Results: The BMP2+SiRunx2 group(C3H10T1/2 cells were treated with AdBMP2 and AdSiRunx2) group was more blue than the BMP2 groupon day 10 proven by Alcian blue staining.And the BMP2+SiRunx2 group of ALP and calcium deposition was less than the BMP2 group.The BMP2+SiRunx2 group showed a higher mRNA level of Col2a1 and aggrecan(P<0.05) and a lower level of Col10a1 、ALP and Col1a1(P<0.05)than the BMP2 group on day 7 and 14. The BMP2+SiRunx2 group showed a higher protein level of Col2a1(P<0.05) and a lower protein level of Col10a1(P<0.05) than the BMP2 group on day 10. The BMP2+SiRunx2group showed a lower protein level of OCN(P<0.05) than the BMP2 group on day 14.Conclusion: The siRNA targeting Runx2 promotes BMP2-induced stem cell chondrogenic differentiation and supresses BMP2-induced stem cell osteogenic differentiation and keep the chondrocyte stype.