FIG. 1.
Rheumatoid arthritis synovial fluid (RASF) suppressed osteogenic activity of mesenchymal stem cells (MSCs) by inducing the expression of intercellular adhesion molecule-1 (ICAM-1). The osteogenic induction medium (OI) contained 10−7 M dexamethasone, 10 mM β-glycerol phosphate, and 50 μM ascorbate-2-phosphate in a base medium of α-MEM supplemented with 10% FBS. In the presence of OI, cell-free RASF incubation suppressed ALP activity and matrix mineralization in MSCs in a dose-dependent manner (A). The mRNA of Runx2 and OCN were downregulated with the incubation of RASF (B, C). In addition, the mRNA and protein expression of ICAM-1 in MSCs was upregulated in a time- and dose-dependent manner after incubation with RASF (D–F). Moreover, the ALP and von Kossa staining results showed that MSCs incubated with RASF partially recovered their osteogenic differentiation capacity after ICAM-1 expression was knocked down (G). In addition, the mRNA of Runx2 and OCN was upregulated when ICAM-1 was silenced (H, I). Scale bars represent 100 μm (A). (*p<0.05; **p<0.01). ALP, alkaline phosphatase; OCN, osteocalcin. Color images available online at www.liebertpub.com/tea