Platelet-derived microvesicles drive vascular smooth muscle cell migration via forming podosomes and promoting matrix metalloproteinase-9 activity

We have shown that platelet-derived microvesicles (PMVs) induce abnormal proliferation, migration, and energy metabolism of vascular smooth muscle cells (VSMCs) after vascular intimal injury. Here, we examined a novel role of podosome in mediating matrix metalloproteinase-9 (MMP-9) dependent VSMC migration induced by platelet-derived microvesicles (PMVs). VSMCs were isolated from the thoracic aortas of male Sprague Dawley (SD) rats and identified with immunofluorescent staining. Blood samples were collected from SD Rats, the platelets were isolated with density gradient centrifugation from the blood samples and activated by collagen I. Intriguingly, proteins expressed in platelets were found to participate in the positive regulation of podosome assembly using GO analysis by DAVID, and most of the proteins were found in extracellular exosomes. Of note, activated platelets indirectly induced VSMC migration via releasing PMVs which was verified using platelets and VSMCs transwell co-culture system. Besides, podosome, an invasive protrusion to mediate extracellular matrix (ECM) remodeling, was formed in VSMCs to induce cell migration. Furthermore, MMP-9 activity detected by gelatin zymography was used to verify the function of the podosome in ECM remodeling. The result indicated that MMP-9 activity was robustly activated in VSMCs to implement the function of the podosome. In addition, gelatin degradation was detected in intact VSMCs using a gelatin degradation assay after co-culture with platelets. Taken together, our data reveal a novel mechanism that PMVs promote VSMC migration via forming podosomes and inducing MMP-9 activity.