Reduced thrombus formation by hyaluronic acid coating of endovascular devices

Biocompatible stent coatings may alleviate problems of increased (sub)acute thrombosis after stent implantation. Hyaluronic acid (HA), a ubiquitous, n onsulfated glycosaminoglycan, inhibits platelet adhesion and aggregation an d prolongs bleeding when administered systemically. However, the effects of immobilized far reducing stent platelet deposition in vivo are unknown. We therefore quantified the antithrombotic effects of coating stainless steel stents and tubes with HA using an established baboon thrombosis model unde r physiologically relevant blood flow conditions, HA-coated and uncoated (c ontrol) stents (3.5 mm in diameter, n=32) and stainless steel tubes (4.0 mm in diameter, 18) were deployed into exteriorized arteriovenous shunts of c onscious, nonanticoagulated baboons. Accumulation of In-111-radiolabeled pl atelets was quantified by continuous gamma-camera imaging during a 2-hour b lood exposure period. HA coating resulted in a significant reduction in pla telet deposition in long (4 cm) tubes (0.24+/-0.15 x 10(9) versus 6.12+/-0. 49X10(9) platelets; P<0.03), short (2 cm) stainless steel tubes (0.18+/-0.0 6X10(9) versus 3.03+/-0.56X10(9) platelets; P<0.008), and stents (0.82+/-0. 20X10(9) versus 1.83+/-0.23x10(9) platelets; P<0.02) compared with uncoated control devices; Thus, HA coating reduces platelet thrombus formation on s tainless steel stents and tubes in primate thrombosis models. These results indicate that immobilized HA may represent an attractive strategy for impr oving the thromboresistance of endovascular devices.