ABSTRACT
AIM: To explore whether strontium ranelate ( Sr ) promotes osteogenic differentiation of rat bone mesenchymal stem cells (BMSCs) through the Hedgehog/Gli1 signaling pathway.METHODS:BMSCs were isolated from 4-week-old rats by adherent culture and induced to differentiate into osteoblasts .According to the experimental purposes , the cells were exposed to different concentrations of Sr , cyclopamine ( Cy, an inhibitor of Hedgehog receptor ) or Gli1-siR-NA.The expression of Gli1 and Runx2 in the cells was detected by Western blotting .The activity of alkaline phosphatase ( ALP) was measured by the method of colorimetry , and the mineralized nodules were observed under microscope with aliz-arin red staining .RESULTS:Exposure to Sr at concentrations of 0.1 to 5 mmol/L for 7 d markedly increased the expres-sion of Gli1 in the BMSCs , and the increase in Gli1 expression was the most obvious following Sr exposure at concentration of 3 mmol/L.Cy at concentration of 10 μmol/L inhibited Sr-induced up-regulation of Gli1 expression.Transfection of the BMSCs with Gli1-siRNA not only obviously inhibited Sr-induced up-regulation of Gli1 and Runx2 ( a downstream protein of Gli1) expression, but also antagonized Sr-induced enhancement of ALP activity and the formation of mineralized nodules . CONCLUSION:The Hedgehog/Gli1 pathway is involved in Sr-induced osteogenic differentiation of rat BMSCs .