Introduction: Preeclampsia is a severe pregnancy complication mostly due to inadequate vascular dilation and remodeling of spiral arteries. VEGF, the major factor for angiogenesis, is necessary for modulating angiogenic processes in the placenta. Hence reduction of VEGF in gestational hypertension may also lead to hypoperfusion and subsequent hypoxia of the fetus in hypertensive pregnancy. Methods: This study aimed at elucidating the mechanism of action of VEGF in preeclampsia. Small activating RNAs (saRNA) were used to upregulate VEGF expression in human trophoblast cells (HTR-8/SVneo). The VEGF expression level was analyzed by real-time quantitative PCR and western blot, while its transfection efficiency was measured by flow cytometer assay. Cell migration was analyzed by a wound scratch assay. NO secretion was detected by determining NO metabolites. eNOS expression was analyzed by western blot. Tube formation function of cells was then analyzed by matrigel migration assay. Results: VEGF expression significantly increased after saRNA transfection (all p < 0.05). NO secretion and eNOS expression significantly increased by saRNA in HTR-8/SVneo cells (p = 0.0003 and 0.032 respectively). The migration ability and tube formation function of HTR-8/SVneo cells were enhanced by saRNA (p = 0.024 and 0.013 respectively). TNIF-alpha inhibited VEGF-downstream eNOS-NO pathway activity as well as cell migration and tubulogenesis, while enforcing the expression of VEGF attenuated all the insults induced by TNF-alpha. Conclusions: Utilizing an RNA activation strategy to increase endogenous VEGF expression could be an emerging and effective approach for the treatment of preeclampsia. (C) 2016 Elsevier Ltd. All rights reserved.