Flow Cytometric Investigation

All stents of the BioDiamond Company have been examined at the Universitaetsklinik Eppendorf (UKE), Hamburg.


The investigation was conducted by Kai Gutensohn, M.D.

In order to test the thrombogenicity in-vitro, three different stents were tested.

1. Stainless steel stents uncoated 2. Stainless steel stents with diamond-like coating 3. Stainless steel stents with diamond-like and additional Heparin coating

The stents were compared to each other in a flow-cytometric evaluation.

The relevant thrombocytes antigens CD 41a, CD 42b, CD 62p and CD 63 were examined (see figure).

The first two antigens correspond to structural epitopes of the thrombocytes and are involved in the process of coagulation like adhesion (CD 42b) and aggregation (CD 41b). CD 62p and CD 63 are neo-antigens and are involved during the process of thrombocytes activation. It was shown recently that CD 62p (P-Selektin) has a thrombogenic potential.

The results show, that in none of the control systems (systems without stents) a change in glycoprotein expression (i.e. all antigens) could be detected. With the exception of one measurement also the structural epitopes (CD 41a, CD 42b) show no significant changes during the test period. The reason is most probably that the shearing strengths of the system was too weak or the expression of the antigens was too strong. Whereas for the thrombocyte activation, remarkable difference in the expression of CD 62p and CD 63 could be detected

  The thrombocyte activity marker CD 62p is reduced in diamond-like coated stents and diamond-like coated stents with heparin compared with uncoated stents.

There are no differences between the diamond-like coated and diamond-like coated heparin stents relating the expression of CD 62p and CD 63.

The strongest thrombocyte activation occurred with the uncoated stainless steel stents. The diamond-like stainless steel stents or the diamond-like steel stents coated with heparin proved to be a significant lower activation of thrombocytes.

The experiments also demonstrated that there is a remarkable reduction of thrombogenic potential by the DLC-stents which is reduced further for the DLC-stents with a heparin coating. The TSO (time until stent occlusion) with coated stents is significantly extended compared with the uncoated stainless steel stents.

TSO of uncoated stainless steel stents, diamond-like coated stents and diamond-like coated stents plus Heparin.

It is clearly shown that the TSO of diamond-like coated stents is enhanced compared to uncoated stents and the TSO of the diamond-like coated stent with additional coating of heparin was even prolonged.

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