Following vein grafting or balloon angioplasty, endothelial damage initiates vascular smooth muscle cell (VSMC) migration to the intima leading to neointimal hyperplasia. Inhibition of VSMC migration is therefore a therapeutic target in vascular disease. Cyclic adenosine monophosphate (cAMP) inhibits VSMC migration and activation of this pathway could be used to prevent neointimal hyperplasia. Prostacyclin analogues, such as beraprost, bind to prostanoid receptors and induce cAMP production. This project aims to characterise the effects of beraprost in VSMC migration and determine the cAMP downstream molecules involved, specifically examining the role of protein kinase A (PKA) and exchange protein activated by cAMP (Epac). Saphenous veins were obtained from patients undergoing coronary artery bypass. VSMCs were primary cultured and migration measured using a chemotaxis chamber. Cells were seeded onto membranes with 8 µm pores and platelet-derived growth factor-BB (PDGF) (10 ng/ml) was added to the lower well of the chemotaxis chamber. Chemotactic cell migration after 4 hours at 37°C was significantly increased with PDGF in comparison to the migration towards the vehicle (PDGF 496 ± 103 as a % of the vehicle, mean ± S.E.M, n=5, p<0.001, ANOVA). Cell migration stimulated by PDGF was significantly inhibited in the presence of beraprost (1 nM) (292% ±17, n=6) in comparison to PDGF alone (450% ± 33, n=6, p<0.001). To examine potential mechanisms of beraprost inhibition of PDGF-induced migration, selective activators for direct activation of PKA (N6-Phenyl-cAMP, 5µM) and Epac (8-CPT-2′-O-Me-cAMP, 2µM) were added to the chemotaxis chamber. Both the Epac and PKA activator significantly reversed migration towards PDGF (PDGF 496% ± 103; PDGF & Epac activator 293% ± 41; PDGF & PKA activator 281% ± 36, n=8 each group, p<0.05). Furthermore, fluorescence resonance energy transfer reveals that therapeutically relevant concentrations of beraprost (1 nM) activates Epac (28% ± 1.2 change in protein activation) in VSMCs but not PKA (-4% ± 0.95, n=3, p<0.05). Following knockdown of PKA with siRNA (70%), beraprost-induced inhibition of migration still occurred through the Epac pathway (negative siRNA, beraprost and PDGF 307% ± 16 versus PDGF 421% ± 25, PKA siRNA, beraprost with PDGF 267% ± 16 versus PDGF 403% ± 25, n=4, p<0.01). Rap1 siRNA (84%) was also used and beraprost-induced inhibition of migration was reversed (negative siRNA, beraprost and PDGF 375% ± 42 versus PDGF 485% ± 23, n=3, p<0.05, Rap1 siRNA, beraprost with PDGF 460% ± 40 versus PDGF 438% ± 23, n=3). Epac protein localisation was examined in VSMCs, and found at the leading edge of the cells, the initial stage of migration. In conclusion beraprost inhibits VSMC migration through activation of Epac; this may provide a new therapeutic target to prevent neointimal hyperplasia.