Testing of platelet deposition on polystyrene surface under flow conditions by the cone and plate(let) analyzer: Role of platelet activation, fibrinogen and von Willebrand factor

Recently, we described a method of testing platelet deposition on extracell ular matrix under flow conditions. The method was used for assessment of pl atelet function in various platelet disorders, for monitoring of replacemen t and anti-platelet therapy. In the present study, we investigated platelet deposition on a polystyrene surface compared with that on extracellular ma trix, under defined shear rates, using the original Cone and Plate(let) Ana lyzer. A correlation of adhesion rate (surface coverage) and aggregate form ation (average size) of platelets from normal citrated blood between polyst yrene and extracellular matrix was observed. Blocking of von Willebrand fac tor binding to glycoprotein Ib by a recombinant von Willebrand factor fragm ent substantially decreased platelet adhesion to both surfaces. Blocking of GPIIb-IIIa by Arg-Gly-Asp-Ser peptide prevented platelet adhesion to the p olystyrene while an extensive adhesion of single platelets to extracellular matrix was observed. Furthermore, platelet adhesion to polystyrene but not to extracellular matrix was completely inhibited by platelet inactivation with prostaglandin Fl. Platelets from patients with severe von Willebrand d isease yielded very low adhesion to both polystyrene and extracellular matr ix. The addition of von Willebrand factor to the blood of these patients or pre-coating of polystyrene surface with von Willebrand factor restored the ability of platelets to adhere and aggregate on the surface. Platelets fro m patients with Glanzmann's thrombasthenia and afibrinogenemia adhered to e xtracellular matrix (with defective aggregate formation)? while they failed to adhere to the polystyrene. Fibrinogen added to afibrinogenemia blood or precoating of the polystyrene with fibrinogen restored the ability of plat elets to adhere and aggregate on the surface. In conclusion, the polystyren e surface, like extracellular matrix, can be used to assess platelet functi on disorders taking in account that platelet deposition on polystyrene unde r flow is absolutely dependent on platelet activation and on the presence o f fibrinogen, von Willebrand factor, and their receptors. (C) 2000 Elsevier Science Ltd. All rights reserved.