Hemocompatibility of treated polystyrene substrates: Contact activation, platelet adhesion, and procoagulant activity of adherent platelets

Abstract

Platelet adhesion to biomaterials is often used as an index of blood compatibility, but a more clinically relevant issue is whether the adherent platelets are able to promote clot formation (i.e., if they are in the procoagulant state). Platelets rapidly generate thrombin when they are in the procoagulant state and the VA/Xa complex is present. We found that adherent platelets are procoagulant by three different methods: binding of FITC-Annexin V, acceleration of thrombin generation in the presence of Xa, Va, and prothrombin; and clotting of recalcified plasma. In the clotting times studies, the effect of adherent platelets on TCPS was completely eliminated by the addition of Annexin V, which is known to bind tightly to procoagulant platelets. The degree of procoagulant activity of adherent platelets was determined by measuring thrombin generation rates in the presence of the clotting factors Va, Xa, and prothrombin and normalizing to the number of adherent platelets. Two key observations were made in these studies. First, the procoagulant activity of platelets adherent to untreated and to several types of treated polystyrenes, as well as to glass and PET, was much greater than the procoagulant activity of unstimulated bulk phase platelets. Little difference in the procoagulant activity of adherent platelets was observed among the materials tested, however. Second, the procoagulant activity of platelets prestimulated with ionophore and subsequently allowed to adhere to Plastek M was much greater than when adherent platelets were stimulated by the adhesion event only. Measured values for platelet adhesion, platelet activation, and contact activation of blood plasma are discussed in the context of their potential combined impact on blood clotting.

Cytological and Subcellular Response of Cells Exposed to the Type-1 RIP Curcin and its Hemocompatibility Analysis

“…Platelet rich plasma (PRP) were isolated as previously described 55 . PRP was dropped onto bare polystyrene culture plates or curcin coated culture plates and was incubated for 1 h at 37uC under static conditions.…”

Toward Engineering a Human Neoendothelium with Circulating Progenitor Cells

“…The blood was centrifuged at 250 g for 15 minutes to obtain platelet-rich-plasma (PRP) supernatant. The PRP preparation and platelet suspension buffer (PSB) used for this experiment was described previously [24]. PRP, diluted 1:10 in PSB, was incubated at 37 C for 30 minutes with monolayers of HAEC, HUVEC, HE-like, and HFF cells cultured on POC.…”

Putting polyphosphates to the test: evidence against platelet-induced activation of factor XII

“…21 Although the exact mechanisms of FXIIa generation in the Amelung assay were not identified, it is, in this context, worth reiterating the well-known fact that in every conventional in vitro assay used to monitor coagulation, small, but not negligible, amounts of FXII will eventually be generated by plastic or metal surfaces in contact with plasma. [22][23][24][25] In the absence of strong activators of coagulation, such artifactual sources of FXIIa will become the predominant procoagulant mechanism. Thus, the identity of the "foreign surface" triggering generation of FXIIa, as referred to in the above quote, is far more likely to have been the moving metal ball used to monitor coagulation in the Amelung instrument than platelet-derived polyphosphates.…”

“…[22][23][24][25] In the absence of strong activators of coagulation, such artifactual sources of FXIIa will become the predominant procoagulant mechanism. Thus, the identity of the "foreign surface" triggering generation of FXIIa, as referred to in the above quote, is far more likely to have been the moving metal ball used to monitor coagulation in the Amelung instrument than platelet-derived polyphosphates.…”