Objective To investigate the effects of celecoxib,a kind of nonsteroidal anti-inflammatory drugs,on the proliferation of human bone mesenchymal stem cells (hBMSCs) and their differentiation into osteoblasts.Methods The bone marrow was harvested from a healthy male volunteer.hBMSCs were isolated by density gradient centrifugation with Ficoll-Paque and expanded in vitro.Celecoxib was added at the concentrations ranging from 10 μmol/L to 100 μmol/L in the process of cellular proliferation and induction.The effect of celecoxib on the proliferation of hBMSCs was evaluated by CCK8 assay.hBMSCs were induced to differentiate into osteoblasts by dexamethasone ascorbic acid and β-glycerophosphate.hBMSCs were treated with 100 μmol/L of celecoxib in the process of osteogenesis before alkaline phosphatase (ALP) activities and calcium deposition were analyzed to determine the effect of celecoxib on the differentiation into osteoblasts.The expression of Runx2,a critical transcription factor of osteogenesis,was analyzed by Western blot.Results Celecoxib inhibited the hBMSCs proliferation in a dose-dependent manner.Such an inhibiting effect of celecoxib was observed at concentrations of 12.5 μmol/L to 100 μmol/L,intensified with the increased concentration.The ALP activities and calcium deposition were reduced by a high dose of Celecoxib and the expression level of Runx2 was also suppressed.Conclusions Celecoxib can suppress the proliferation and osteogenesis of hBMSCs in a dose-dependent manner.Long term administration of celecoxib,particularly high dose usage,should arouse concerns from both the patients and medical staff about the effect of celecoxib on the osteogenesis of hBMSCs. Key words: Bone marrow cells; Mesenchymal stem cells; Osteoblasts; Transcription factors; Celecoxib