Objective: In order to investigate the role of shear stress in the regulation of endothelial function, we assessed here effects of shear stress on tissue-type plasminogen activator in human endothelial progenitor cells (EPCs).
Methods: The peripheral blood mononuclear cells were separated from healthy adult and inducted into EPCs, which were identified by double staining for the fluorescent labeled acetylated-LDL and lectin. EPCs were seeded on the small diameter artificial vessels, and then divided into four different experimental groups including stationary group, low-flow shear stress group (5 dyn/cm(2)), medium-flow shear stress group (15 dyn/cm(2)) and high-flow shear stress group (25 dyn/cm(2)). The levels of t-PA in EPC culture medium at 0 hour, 5 hours, 10 hours, 15 hours, 20 hours and 25 hours after culture were measured by enzyme-linked immunosorbent assay.
Results: The peripheral blood mononuclear cells differentiated into EPCs after induction, which were positively labeled by fluorescent acetylated-LDL and lectin. Shear stress enhanced production of the t-PA by EPCs, which was paralleled to levels and times of shear stress.
Conclusions: Shear stress increases t-PA secretion by human EPCs, suggesting that shear stress not only regulates vascular endothelial function but also participates in the pathogenesis of arteriosclerosis.