Biocompatibility of Tantalum Coronary Stents: Investigations by Flow Cytometry

Abstract

In our study, we applied fluorescence-activated flow cytometry to examine activation-dependent alterations of platelet antigens caused by contact with coronary tantalum stents. In an in vitro model, tantalum wire stents (n = 1O) were placed in a silicon tubing and platelet-rich plasma (PRP) was filled into the system. After recalcification, PRP was gently moved by a roller pump. Over the course of 10 min, aliquots were drawn at fixed time intervals. The sampIes were immediately prepared for flow cytometry and labeled with monoclonal antibodies against CD62p, CD63, CD41a and CD42b. The mean channel fluorescence intensity (MCFI) of GMP140 and gP53 increased within the first minutes and continued to rise over the whole time course. There was a significant difference in MCFI between the tube with a stent and the control tube without a stent (CD62p, P < 0.05; CD63, P < 0.005)· The increase in CD62p and CD63 expression can be explained by the contact of platelets with the artificial surface of the stent and the shear forces of the metallic mesh. Platelets expressing activation-dependent neoantigens on their surface, especially P-selectin, are known to be associated with a higher predisposition for thrombosis. Therefore, additional medical precaution may help to prevent restenosis in these patients.