Promotion of osteogenesis through beta-catenin signaling by desferrioxamine

Desferrioxamine, an iron chelator with "hypoxia-mimetic" activity, promotes bone mineralization when used in aluminum-overloaded dialysis patients. However, the effect of desferrioxamine on osteoblastic differentiation from pluripotent mesenchymal stem cells (MSCs) has not been reported. In this study, pluripotent human MSCs and murine mesenchymal C3H10T1/2 cells were simultaneously treated with desferrioxamine and bone morphogenetic protein-2 (BMP2). In BMP2-treated MSCs, desferrioxamine levels of 15 microMu were found to increase alkaline phosphatase (ALP) activity and calcium deposition, which were the markers of osteoblastic differentiation. These effects of desferrioxamine were accompanied by promoted phosphorylation of glycogen synthase kinase 3beta (GSK-3beta) and increased beta-catenin protein content, a direct GSK-3beta substrate. Knockdown of beta-catenin by RNA interference eliminates this positive effect of desferrioxamine on ALP activity. Taken together, these data demonstrate that desferrioxamine plays a direct role in the differentiation of mesenchymal stem cells by activating beta-catenin signaling cascades.