Restenosis, thrombosis formation and delayed endothelium regeneration continue to be problematic for
coronary artery stent therapy. To improve the hemocompatibility of the cardiovascular implants and
selectively direct vascular cell behavior, a novel kind of heparin/poly-L-lysine (Hep/PLL) nanoparticle
was developed and immobilized on a dopamine-coated surface. The stability and structural characteristics
of the nanoparticles changed with the Hep:PLL concentration ratio. A Hep density gradient was created
on a surface by immobilizing nanoparticles with various Hep:PLL ratios on a dopamine-coated
surface. Antithrombin III binding quantity was significantly enhanced, and in plasma the APTT and TT
times as coagulation tests were prolonged, depending on the Hep density. A low Hep density is sufficient
to prevent platelet adhesion and activation. The sensitivity of vascular cells to the Hep density is very different:
high Hep density inhibits the growth of all vascular cells, while low Hep density could selectively
inhibit smooth muscle cell hyperplasia but promote endothelial progenitor cells and endothelial cell proliferation.
These observations provide important guidance for modification of surface heparinization. We
suggest that this method will provide a potential means to construct a suitable platform on a stent surface
for selective direction of vascular cell behavior with low side effects.