The Impact Of Normal Shear Stress On Migration Of Endotheial Cell Cocultured With Smooth Muscle Cells

Vascular endothelial cells (ECs) are constantly exposed to blood flow-induced shear stress, which behaviors are strongly influenced by the neighboring vascular smooth muscle cells (VSMCs). The adhesion and migration of ECs are essential functions to keep the vascular homeostasis. Thus, the research in the area of EC biology will require considering mechanical factors and cell-to-cell interaction between VSMCs and ECs.In this paper, using a coculture system, we firstly investigated the effect of interaction of ECs and VSMCs on adhesion of ECs. And then the difference of EC migration of VSMC/EC co-culture or cultured alone under static conditions and in response to shear stress was assessed by a parallel-plate co-culture flow chamber system. The results showed that ECs co-cultured with VSMCs exhibited a significant increase in the number of adherent cells, which was correlated with enhanced assembly of FA and increased focal adhesion area. At the same time, VSMCs also prompted ERK and paxillin phosphorylation of ECs and downregulated its microtubule polymerization state. Using Trichostatin A which can reverse microtubule polymerization state, it was demonstrated that the adhesion and activation of ERK and paxilllin were impacted by microtubule polymerization state.With Transwell migration assays, we also demonstrated that VSMCs induced cocultured EC migration; when laminar shear stress (1.5 Pa, 15 dynes/cm2, NSS) applied to ECs cultred alone for 12 h, the EC migration was also significantly elevated; when NSS and VSMCs impacted ECs at the same time, the migration of ECs co-cultured with VSMCs was not prompted more under NSS. The changes in EC migration had a consisitent correlation with the level of acetylated microtubule and HDAC6. While HDAC6 was inhibited by tribytyrin or specific small interference RNA, EC migration was impacted, and followed hyperacetylation of tubulin.These results indicate that NSS and VSMCs regulate EC migration, which may be an atheroprotective function on the vessel wall to keep the vascular homeostatis. Meanwhile, microtubule/ERK/paxillin pathway may play a key role in EC migration modulated by NSS and VSMCs.