A macrofluidic model to investigate the intrinsic thrombogenicity of clinically used stents and develop less thrombogenic stents.

Microfluidic blood flow models have been instrumental to study the functions of blood platelets in hemostasis and arterial thrombosis. However, they are not suited to investigate the interactions of platelets with the foreign surfaces of medical devices such as stents, mainly because of the dimensions and geometry of the microfluidic channels. Indeed, the channels of microfluidic chips are usually rectangular and rarely exceed 50 to 100 μm in height, impairing the insertion of clinically used stents. To fill this gap, we have developed an original macrofluidic flow system, which precisely reproduces the size and geometry of human vessels and therefore represents a biomimetic perfectly suited to insert a clinical stent and study its interplay with blood cells. The system is a circular closed loop incorporating a macrofluidic flow chamber made of silicone elastomer, which can mimic the exact dimensions of any human vessel, including the coronary, carotid or femoral artery. These flow chambers allow the perfect insertion of stents as they are implanted in patients. Perfusion of whole blood anticoagulated with hirudin through the device at relevant flow rates allows one to observe the specific accumulation of fluorescently labeled platelets on the stent surface using video-microscopy. Scanning electron microscopy revealed the formation of very large thrombi composed of tightly packed activated platelets on the stents.