Fig. 3: PM exposure markedly suppresses the multilineage differentiation potential and induces the apoptosis of endometrial stem cells in vitro.

Endometrial stem cells were cultured in adipocyte or osteoblast differentiation medium with or without PM (25 μg/ml). The inhibitory effects of PM exposure on adipocyte (a) and osteoblast (b) differentiation were evaluated by oil red O and alizarin red staining, respectively. The relative quantification of calcium mineral content and lipid droplet formation in differentiated cells was performed by measuring the absorbance at 500 nm and 570 nm, respectively. Endometrial stem cells were cultured with or without PM (25 μg/ml) for 72 h, and the increase in the level of cleaved caspase-3 following PM exposure was then analyzed by western blotting (c). PM-induced apoptotic DNA condensation and fragmentation after incubation in the absence of PM (25 μg/ml) for 72 h were analyzed using DAPI staining (d). The decrease in cell viability following PM exposure (5 and 10 μg/ml) for 72 h was detected via an MTT assay in both endometrial stem cells and terminally differentiated cells (fibroblasts and vascular endothelial cells). Cell viability (%) was calculated as the percent of the viability of cells treated with the vehicle control (e). DAPI was used to label nuclei. β-Actin was used as the internal control. The bar graphs show the average of three independent experiments. Significant differences are presented. *p < 0.05, **p < 0.005, and ***p < 0.001 (two-sample t-test).