Shear stress contributes to t-PA mRNA expression in human endothelial progenitor cells and nonthrombogenic potential of small diameter artificial vessels.

Seeding endothelial progenitor cells (EPCs) onto the surface of vascular grafts has been proved to be a promising strategy to improve nonthrombogenic potentials of small diameter artificial vessels. Here, we investigated whether in vitro shear stress modulates the tissue-type plasminogen activator (t-PA) secretion and mRNA expression in human EPCs and improves patency of the EPC-seeded polyurethane small diameter vascular grafts implanted in the canine carotid artery in vivo. In vitro shear stress, in a dose-dependent manner, increased t-PA secretion and mRNA expression of human EPCs. The in vivo implantation of EPC-seeded vascular grafts remained highly patent in shear stress pretreatment compared with stationary condition. The present findings demonstrate for the first time that in vitro shear stress can enhance t-PA secretion and gene expression in human EPCs, which contributes to improvement in nonthrombogenic potentials of EPC-seeded small diameter artificial vessels with maintenance of in vivo highly patency rate.