Abstract:

BACKGROUND: Postmenopausal osteoporosis often results from upregulation of inflammatory factors. Pathogenic bacteria in periodontal tissues can generate some virulence factors destroying host tissues, such as lipopolysaccharide, pilus, and lectin.
OBJECTIVE: To investigate osteogenic differentiation property of bone marrow mesenchymal stem cells under lipopolysaccharide stimulation in ovariectomized mice, and to preliminarily explore the cellular and molecular biological mechanisms underlying estrogen deficiency patients susceptible to periodontitis, which attempting to provide laboratory evidences for periodontitis prevention of postmenopausal women. 
METHODS: Thirty female two-month-aged Kunming mice were randomly divided into ovariectomized group and sham group. Two groups of bone marrow mesenchymal stem cells were subject to osteogenic induction and cultured in media containing different concentrations of lipopolysaccharide (0, 10, 100 μg/L). After osteogenic inductions, alkaline phosphatase staining and alizarin red staining were performed, and expression of Runx2, Ocn, Alp were detected using RT-RCR.
RESULTS AND CONCLUSION: After 7 days of osteogenic differentiation, cells expressed alkaline phosphatase; after 21 days, alizarin red staining was positive and mineralized nodules were visible. mRNA expressions of Ocn, Runx2, and Alp in 100 μg/L lipopolysaccharide group were significantly decreased (P < 0.05). Compared with the control group, the expressions of three target genes were significantly declined after intervention with lipopolysaccharide (P < 0.05). These findings indicate that lipopolysaccharide reduces the osteogenic ability of bone marrow mesenchymal stem cells, especially in ovariectomized mice, which may be one of cellular and molecular mechanisms by which estrogen deficiency leads to increased susceptibility of periodontitis.

Key words: tem cells, mesenchymal stem cells, bone marrow, periodontitis, osteoporosis, lipopolysaccharides