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AimTo purify the platelet aggregation inhibitor from Echis multisquamatis snake venom (PAIEM) and characterize its effect on platelet aggregation and HeLa cell proliferation.MethodsSodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) and matrix assisted laser desorption/ionization time-of-flight (MALDI-TOF) were used for PAIEM identification. Platelet aggregation in the presence of PAIEM was studied on aggregometer Solar-AP2110. The changes of shape and granularity of platelets in the presence of PAIEM were studied on flow cytometer COULTER EPICS XL, and degranulation of platelets was estimated using spectrofluorimetry. Indirect enzyme-linked immunosorbent assay was used for the determination of target of PAIEM on platelet surface. An assay based on 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide was used to evaluate the effect of PAIEM on the proliferation of HeLa cells in cell culture.ResultsThe molecular weight of the protein purified from Echis multisquamatis venom was 14.9 kDa. Half-maximal inhibitory concentration (IC50) of PAIEM needed to inhibit adenosine diphosphate (ADP)-induced platelet aggregation was 7 μM. PAIEM did not affect thrombin- or ADP-induced platelet activation, but it did prevent binding of the anti-IIb antibody to glycoprotein IIb/IIIa (GPIIbIIIa)-receptor of adhered platelets and inhibited the viability of HeLa cells by 54%.ConclusionAs a member of the disintegrin family, PAIEM inhibited platelet aggregation and cell proliferation possibly by blocking integrin-mediated interactions. However, it did not impair cellular signaling causing any changes in platelet shape and granularity and did not affect ADP-induced platelet degranulation. This disintegrin was shown to be a potent inhibitor of integrin-mediated cellular interactions including platelet aggregation or cancer cell proliferation.

Coagulation potential (CP), overall hemostasis potential (OHP) and fibrinolysis potential (FP) in plasma of donors and patients with myocardial infarction (MI), stroke (St) and hip joint diseases (HJD) have been investigated using M. Blomback’s global hemostasis assay. Plasma samples of the patients were analyzed with APTT reagent in the presence or absence of t-PA. It was found that the ratio of values of СP, OHP and FP in plasma of patients to those of donors plasma were 78, 60 and 123% at MI; 157, 155 and 162% at St; 128, 131 and 124% at HJD. CP to FP ratio that indicated balance between coagulation and fibrinolytic systems activities were 4.13, 2.5, 4.0 and 4.26 in plasma of donors and MI, St and HJD patients, respectively. These results are evidence of increased fibrinolytic activity in plasma of MI patients. Lag-periods of plasma clotting of MI, St and HJD patients were prolonged by 2.3, 7.2 and 1.5-fold, respectively. Pearson’s correlation analysis between parameters, obtained in vitro studies using global hemostasis assay, and concentrations of the molecular markers (soluble fibrin and D-dimer), which formed in vivo in plasma of MI, St and HJD patients, did not reveal any relationship between them.

Meizothrombin (MT) is one of prothrombin derivatives which appears in haemostasis activation area. However, its role in haemostasis regulation isn't clear. We studied the role of MT in fibrin formation, platelet activation and aggregation. A new effective method of obtaining MT from native human prothrombin was developed using immobilised prothrombin activator from Echis multisquamatis venom. The protein was stable and electrophoretically pure. Platelet-rich plasma for aggregation study and gel-sieved platelets for flow-cytometry were separated from blood of healthy donors. It was shown that MT transformed fibrinogen to fibrin and activated clotting factor XIII. MT didn't activate gel-sieved intact platelets, but in platelet-rich plasma, increased platelet aggregation induced by ADP, collagen and adrenalin.

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