Abstract: Objective: To investigate the effect of PM2.5 on the survival rate, the migration ability and the invasion ability of human chorionic trophoblast cell line, HTR8-SVneo, and to explore the possible mechanism of the adverse pregnancy outcome induced by PM2.5. Methods：The in vitro cultured HTR8-SVneo cells were treated with PM2.5. The cell proliferation was analysed by CCK8. Five concentrations of 0, 30, 60, 120 and 200 μg/mL were selected. The cell migration was detected by Laser holographic cell analysis and imaging system, while the cell invasion by the Transwell experiment. The mRNA and protein expressions of MMP2, MMP9, TIMP1 and TIMP2 were measured by qPCR and Western Blot, while the activities of MMP2 and MMP9 by a gelatin zymography. Results：The proliferation of HTR8-SVneo cells was significantly inhibited by PM2.5 treatment (P＜0.05), while the migration distance and the number of cells penetrating the membrane were decreased (P＜0.05). The mRNA and protein expressions of MMP2, MMP9, TIMP1 and TIMP2 were significantly increased in PM2.5 exposed groups(P＜0.05), and the increased degree of MMPs was lower than TIMPs. The activities of MMP9 in all PM2.5 treatment groups were significantly increased when compared with the control group (P＜0.05). Conclusions：PM2.5 can induce the cellular damage of HTR8-SVneo cells, while PM2.5 can decrease the cell migration and invasion by inducing the imbalance between MMPs and TIMPs. These pathophysiological changes are related with the adverse pregnancy outcomes.

Key words: Air pollutants, Trophoblasts, Cell migration assays, Matrix metalloproteinase 2, Matrix metalloproteinase 9, Tissue inhibitor of metalloproteinase-1, Tissue inhibitor of metalloproteinase-2