Notch signaling stimulates osteogenic differentiation of human bone marrow-derived mesenchymal stem cells

Notch signaling is one of the most important pathways mediating cell determination and differentiation. In this study, the roles of Notch signal in the regulation of osteogenic differentiation of human bone marrow mesenchymal stem cells (hMSCs) were investigated. The expression of Notchl, Jaggedl and DTX1 detected by reverse transcription polymerase chain reaction (RT-PCR) suggested that Notch signal might exhibit a physiological regulatory role in the differentiation of MSCs. Constitutive expression of the intracellular domain of Notchl (ICN), the active form of Notchl protein, can activate Notch signal in cells without ligands’ binding. hMSCs were isolated, expanded, and infected with retrovirus carrying green fluorescent protein (GFP) gene orICN. Overexpression of ICN in hMSCs resulted in enhanced osteogenic differentiation induced by dexamethasone (Dex), which was characterized by an increase of cellular alkaline phosphatase (ALP) activity and calcium deposition. These results indicate that Notch stimulates differentiation of MSCs into osteoblasts.