Cellular proliferation and extracellular matrix mineralization of hGMSCs after EMD stimulation. (A) The cellular proliferation of hGMSCs after EMD stimulation for 24 hours and 48 hours, by MTS assay (means ± standard deviations, * and #: significant difference at P <0.05 versus 0 and 25 μg/ml EMD, respectively). (B) The extracellular matrix mineralization, stained with ARS, of hGMSCs after EMD stimulation for up to four weeks. (C) Semi-quantitative measurments of the ARS dye from the cultured cells during the osteogenic differentiation of hGMSCs after the EMD stimulations presented in B (means ± standard deviations, and *: significant difference at P <0.05 versus 0 μg/ml EMD at each observation interval). ARS, Alizarin red S; EMD, enamel matrix derivative; hGMSCs, human gingiva-derived mesenchymal stem cells.