Abstract 14668: Epac1 Deficiency Inhibit Neointima Formation After Vascular Injuryin vivo
Introduction: Vascular remodeling after mechanoinjury largely depends on the migration of smooth muscle cells. We have reported that Exchange protein activated by cyclic AMP 1 (Epac1) promotes vascular smooth muscle cell migration. However, the role of Epac1 in advancing vascular remodeling upon vascular injury,in vivoremains unknown.
Hypothesis: We hypothesized that Epac1 promoted vascular remodeling upon vascular injury.
Methods:Smooth muscle cells in primary culture were obtained from the Epac1+/+ and Epac1-/- mice. Migration patterns were examined by using smooth muscle cells under stimulation with platelet-derived growth factor (PDGF)-BB or basic fibroblast growth factor (bFGF). Expression of phosphorylated cofilin and IQGAP1 were evaluated by Immunocytochemistry to assess the formation of lamellipodia and establishment of cell polarity. The effect of Epac1 on vascular remodeling was examined by using femoral artery injury mouse models of Epac1+/+ and Epac1-/-. Four weeks after injury, the area of intimal thickening, and internal lumen were evaluated by Elastica van Gieson's staing.
Results: Path length of Epac1-/- mice smooth muscle cells migration under stimulation with PDGF for 8 hours was significantly shorter than that of Epac1+/+ (97±3.7 vs. 148±5.4(µm), p<0.0001, n=114,126). Rate of lamellipodia formated cell with dephosphorylated cofilin in Epac1-/- was significantly lower than that in Epac1+/+ under stimulation with PDGF(6±3.5 vs. 41±5.1(%), p<0.0001, total cell count 714, 4 independent experiments).Rate of polarized cells with IQGAP1 localization at cell leading edge in Epac1-/- was significantly lower than that in Epac1+/+ under stimulation with PDGF (5±2.5 vs. 32±4.7(%), p<0.005, total cell count 542, 5 independent experiments). Similar results were obtained with smooth muscle cells stimulated by bFGF. Ratio intimal thickening to smooth muscle layer of Epac1-/- was significantly lower than that of Epac1+/+(2.2±1.0 vs. 3.9±1.3, p<0.05, n=5). Area of internal lumen of Epac1-/- mice were significantly increased compared to that of Epac1+/+ (6.7-fold, p<0.05, n=5)
Conclusion:These results suggest that Epac1 deficiency inhibit neointima formation after vascular injury in vivo.
- © 2011 by American Heart Association, Inc.