Mesenchymal stem cells (MSCs) are multipotent stem cells which are able to differentiate into various lineages including osteoblasts, adipocytes and chondrocytes. They can be isolated from several tissues including bone marrow, adipose tissue, placenta and umbilical cord. Although MSCs could be differentiated into osteoblasts under appropriate culture
condition, their osteogenic differentiation capacity is still not very efficient. Previous studies reported that TNF-α could promote osteogenic differentiation of bone marrow derived MSCs by triggering NF-κB signaling pathway. However, the effect of TNF-α on the osteogenic differentiation ability of umbilical cord derived MSCs has not been investigated. This study aimed to examine the effect of TNF-α on osteogenic differentiation of umbilical cord derived MSCs (UC-MSCs). The results demonstrated that TNF-α has osteopromotive effect for umbilical cord derived MSCs as evidenced by more matrix
mineralization and alkaline phosphatase staining. Interestingly, UC-MSCs cultured in osteogenic differentiation medium supplemented with TNF-α had significantly increase expression of Osteocalcin, the marker of mature osteoblasts,when it was compared to UC-MSCs cultured in osteogenic differentiation medium without TNF-α (p<0.05). On the contrary, the UCMSCs cultured in osteogenic differentiation medium supplemented with TNF-α had significantly lower levels of Runx2 and Osterix (the markers of immature osteoblasts) than UC-MSCs cultured with osteogenic differentiation medium without TNF-α. The present study suggested that TNF-α promotes osteogenic differentiation of UC-MSCs. The data add a possibility for the use of UC-MSCs as an alternative source for cell replacement therapy in bone defect.

Keywords: Mesenchymal stem cell, Umbilical cord, TNF-α, Osteogenesis