Vascular smooth muscle cell (VSMC) phenotypic modulation plays a pivotal role in atherothrombotic diseases. Thrombin generation at the surface of VSMCs and activation of integrin mechanotransduction pathways represent potential mechanisms. Here, we examine whether mechanical stretch increases thrombin generation on cultured rat aortic VSMCs.

We used a model of cultured rat aortic VSMCs submitted to cyclic stretch (Flexcell, 10% at 1 Hz). Cyclic stretch during 60 and 360 minutes induced a differentiated contractile VSMC phenotype without apoptosis and up-regulated integrin α_vβ₃ expression 1.3 fold. Cyclic stretch stimulated binding of prothrombin to VSMCs and increased the subsequent thrombin generation by 67% and 30% respectively. It also produced time-dependent phosphorylation of Src, FAK and Akt as well as increased ILK phosphorylation at 15 minutes. Talin cleavage was increased between 5 and 60 minutes. The α_vβ₃ antagonist cRGDPV and α_v-siRNA blocked these responses. A talin-siRNA decreased stretch-induced α_v expression and the phosphorylation of Src, FAK, Akt and ILK. ILK-siRNA had no effect on α_v expression but inhibited phosphorylation of Akt and talin at 360 minutes.

These results demonstrate that cyclic stretch stimulates the generation of thrombin on rat VSMCs via activation of integrin α_vβ₃ pathways. They further suggest that intravascular generation of thrombin may be regulated by integrin α_vβ₃ antagonists in patients with high pulse pressure.