Tag Archives: platelets

Plasminogen influence on the PAI-1 release by human platelets

O. I. Yusova*, T. V. Grinenko, T. F. Drobot’ko, A. O. Tykhomyrov

Department of Enzyme Chemistry and Biochemistry, Palladin Institute of Biochemistry,
National Academy of Sciences of Ukraine, Kyiv;
*e-mail: yusova07@gmail.com

Received: 06 February 2024; Revised: 27 March 2024;
Accepted: 31 May 2024; Available on-line: 17 June 2024

РАІ-1 (plasminogen activator inhibitor type 1), as a major physiological inhibitor of tissue plasminogen activator and urokinase, plays a key role in the regulation of fibrinolysis in vivo. Besides, PAI-1 suppresses plasmin formation and affects cell migration through interaction with vitronectin. РАІ-1 is secreted from α-granules of platelets upon stimulation of cells by agonists. The aim of our study was to explore the effects of Glu- and Lys-forms of plasminogen on PAI-1 secretion by platelets and to evaluate the possible role of plasminogen in modulation of agonist-induced PAI-1 release. The secretion of PAI-1 by platelets was investigated by the Western blot analysis. It has been established that depending on the agonist, PAI-1 can be released from platelets in a free form, in a complex with a tissue plasminogen activator, as well as in the form of high-molecular complexes that contain a tissue activator and vitronectin molecules. The revealed induction of PAI-1 secretion under the action of Gly- and Lys-forms of plasminogen indicates their ability to activate intracellular signaling pathways that regulate the release of platelet α-granules. Our findings may be of importance for elucidating the pathogenetic mechanisms of many diseases associated with abnormally enhanced platelet function and PAI-1-related disorders.

Antioxidants as supplements during drug-induced thrombocytopenia: a comparative analysis of Vanillic acid, L-carnitine and Caripill™

M. Mithun, V. Rajashekaraiah*

Department of Biotechnology, School of Sciences,
JAIN (Deemed-to-be University), Bengaluru, Karnataka, India;
*e-mail: vani.rs@jainuniversity.ac.in

Received: 20 September 2023; Revised: 07 November 2023;
Accepted: 01 February 2024; Available on-line: 26 February 2024

Drug-induced thrombocytopenia (DIT) is a disorder where platelet count declines as an adverse effect of therapeutic drugs. Plant extract of C. papaya Caripill™ is known to elevate platelet count under thrombocytopenic conditions. To evaluate the contribution of supplements with antioxidant potential to treat DIT, the comparative study of Caripill™, vanillic acid L-carnitine effect on platelet count and indices of oxidative stress in a model of rat thrombocytopenia induced through oral administration of hydroxyurea was performed. Wistar rats were grouped into four categories with five animals in each group: control (without any treatment); control + antioxidants; thrombocytopenia; thrombocytopenia + antioxidants. The above-mentioned antioxidants were supplemented orally at 50 mg/kg for 7 days. The level of lipid peroxidation products­, superoxides, protein carbonyls and sulfhydryls, SOD and CAT activity in isolated platelets as oxidative stress markers, and indices of platelets aggregation and ATP secretion as functional markers were used. Vanillic acid was shown to be beneficial, similar to Caripill™, during hydroxyurea-induced thrombocytopenia by maintaining platelet functions, enhancing both the antioxidant capacity of platelets and its number. L-carnitine efficiently up-regulated the enzymatic antioxidants, maintained platelet functions and protected lipids and proteins from oxidation in thrombocytopenic rats, however, it could not improve the platelet count. These findings open new avenues for employing the studied antioxidants as supplements for therapeutic purposes.

Validation of the diagnostics algorithm to monitor coagulation parameters in pregnant women

D. S. Korolova1, A. O. Pavlenko1, A. Altorjay2, S. I. Zhuk3,
I. V. Us3, Y. Tsaryk1, A. Suranyi2, V. O. Chernyshenko1*

1Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
2Albert Szent-Györgyi Medical School, University of Szeged, Hungary;
3P. L. Shupyk National Medical Academy of Postgraduate Education, Kyiv, Ukraine;
*e-mail: bio.cherv@gmail.com

Received: 19 May 2023; Revised: 05 June 2023;
Accepted: 07 June 2023; Available on-line: 11 July 2023

Thrombotic events are among the most dangerous complications of pregnancy. Therefore, selection of appropriate tests and standardization of techniques used for accurate diagnostics of blood coagulation system state is of great importance. In this present study, we monitored several molecular markers of the dangers of intravascular thrombus formation and estimated the platelet function in pregnant women during­ gestation. We performed independent measurements using the same methodology for different cohorts of patients recruited in Kyiv (Ukraine) and in Szeged (Hungary). D-dimer and soluble fibrin were measured using ELISA. Protein C (PC) level was estimated using chromogenic substrate assay. Fibrinogen concentration was measured by spectrophotometry using thrombin-like enzyme. Platelet function was estimated by aggregometry­. Statistical data analysis was performed using the Kruskal-Wallis test. Statistically significant increases of fibrinogen concentration from first to third gestational trimester was shown for both studied cohorts of patients (5-6 mg/ml at third trimester on average). Applied methods allowed us to detect the same tendencies of decreases in PC level as well as the appearance of moderate amounts of D-dimer (up to 300 ng/ml) and SF (up to 10-15 ug/ml). Platelet function was increased on the first trimester of pregnancy and decreased during­ following trimesters slightly. Results indicated the changes in the blood coagulation system of pregnant women during gestation with the same effectiveness independently of the selected cohorts, time and place of measurements. The application of the proposed diagnostics algorithm may allow estimating the risk of thrombotic complications during pregnancy.

Purification and characterization of platelet aggregation inhibitor from the venom of Bitis arietans

O. Platonov1*, V. Nikulina1, Y. Kucheryavyi1,
V. Gryshchuk1, Y. Stohniy1, V. Chernyshenko1, O. Slominskyi1,
A. Rebriev1, K. Savchenko1,2, L. Garmanchuk2

1Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
2ESC “Institute of Biology and Medicine”,
Taras Shevchenko National University of Kyiv, Ukraine;
*e-mail: chaosplaton@gmail.com

Received: 28 January 2022; Revised: 03 October 2022;
Accepted: 20 September 2022; Available on-line: 19 December 2022

Disintegrins are the antagonists of integrin receptors that can be found mostly in snakes’ venom. They can inhibit platelet aggregation, thus preventing the formation of blood clots. By blocking the integrin receptors of cancer cells, disintegrins can inhibit proliferation and metastasis. Thus, the search for new sources of disintegrins and development of methods of their purification is an important task of modern biotechnolo­gy. This work was dedicated to the purification and characterization of inhibiting polypeptides from Bitis arietans­ venom. Crude venom of B. arietans was fractionated using ion-exchange chromatography on Q Sepharose followed by size-exclusion chromatography on Superdex 75 using FPLC method. Analysis of molecular weight of protein components was performed using SDS-PAGE and MALDI-TOF analysis on Voyager-DE. Aggregation of platelet-rich plasma (PRP) in the presence of platelet aggregation inhibitor was investigated using aggregometry on the AR2110. MTT test was used for measuring HeLa cells proliferation and survival in vitro. Two-step chromatography allowed us to obtain fraction that contained polypeptides possessing the dose-dependent inhibitory action on adenosine diphosphate (ADP)-induced platelet aggregation in PRP. SDS-PAGE showed that obtained fraction contained two polypeptides with molecular weight 9.0 and 13.67 kDa according­ to MALDI-TOF analysis. Purified polypeptides inhibited ADP-induced platelet aggregation with IC50 0.09 mg/ml. However, 0.005 mg/ml of fraction suppressed viability of HeLa cells according to MTT test on 20%. Discovered biological effects of fractions allowed us to conclude the possible use of these polypeptides as anti-aggregatory or anti-proliferative agents.

Aggregation of platelets, proliferation of endothelial cells and motility of cancer cells are mediated by the Bβ1(15)-42 residue of fibrin(ogen)

Y. M. Stohnii1, M. V. Ryzhykova1, A. V. Rebriev1,
M. D. Kuchma2, R. Y. Marunych1, V. O. Chernyshenko1*,
V. A. Shablii2, N. M. Lypova3, O. Yu. Slominskyi1,
L. V. Garmanchuk4, T. M. Platonova1, S. V. Komisarenko1

1Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv, Ukraine;
2Institute of Cell Therapy, Kyiv, Ukraine;
3University of Louisville, USA;
4ESC “Institute of Biology and Medicine”, Taras Shevchenko National University of Kyiv, Ukraine;
*e-mail: bio.cherv@gmail.com

Received: 23 December 2019; Accepted: 27 March 2020

The fibrinogen molecule contains multiple binding motifs for different types of cellular receptors, acting as a molecular link between coagulation and cell adhesion. In this study we generated a truncated form of the fibrinogen molecule lacking the Bβ1-42 sequence by site-specific proteolysis and evaluated the role of the fragment in adhesive capabilities of platelets, endothelial and cancer cells. Fibrinogen with the removed Bβ1-42 sequence and fibrin without the Bβ15-42 fragment (desβ1-42 fibrinogen and desABβ15-42 fibrin) were obtained by proteolysis using the specific protease from the venom of Echis multisquamatis. The cleaved fragment was purified by HPLC and was identified using MALDI-TOF. ADP- and collagen-induced aggregation of washed platelets in the presence of fibrinogen desBβ1-42 was studied using an aggregometer. Proliferation of mice aortic endothelial cells (MAEC) and human umbilical vein endothelial cells (HUVEC) was studied using the fibrin desABβ15-42 as the scaffold. Cell viability was quantified by the MTT test (MAEC). Generation time was calculated for the estimation of proliferative activity of HUVEC. Lung cancer cell line Н1299 was used to evaluate cancer cell motility in vitro using the scratch assay. Direct comparison of cellular behavior in the presence of truncated vs native forms demonstrated attenuated cell adhesion in the presence of fibrinogen desBβ1-42 and fibrin desBβ15-42. The platelet aggregation rate was only slightly decreased in the presence of fibrinogen desBβ1-42 but resulted in 15-20% disaggregation of adhered platelets. We also observed the substantial decrease of generation time of HUVEC and inhibition of viability of MAEC cells grown on scaffolds of a desABβ15-42 matrix. Finally, desBβ1-42 modulated the motility of H1299 cells in vitro and suppressed the wound healing by 20% compared to the full-length fibrinogen. We postulate that fragment 1-42 of the BβN-domain of fibrinogen is not sufficient for platelet aggregation, however it may contribute to platelet clot formation in later stages. At the same time, this fragment may be important for establishing proper cell-to-cell contacts and cell viability of endothelial cells. Also, 1-42 amino acid fragment of the BβN-domain supported the migration of cancer cells suggesting that interactions of fibrinogen with cancer cells could be a target for anticancer therapy. The Bβ1-42 fragment of fibrinogen contributes to efficient intracellular interactions of different types of cells, including platelets, endothelial cells and cancer cells.

Plasminogen modulates formation and release of platelet angiogenic regulators

A. A. Tykhomyrov, D. D. Zhernosekov, T. V. Grinenko

Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: artem_tykhomyrov@ukr.net

Received: 19 July 2019; Accepted: 29 November 2019

Platelets store, produce and release a variety of angiogenesis regulators, which can contribute to both normal tissue repair and angiopathy-associated pathologies. Plasminogen has been earlier shown to regulate some platelet functions, but if it is able to modulate angiogenic capacities of platelets is still poorly studied. Thus, the aim of the present study was to evaluate the effects of different plasminogen forms on the formation and secretion of angiogenic protein regulators by platelets. Human washed platelets were obtained by gel-filtration on Sepharose-2B. The levels of P-selectin (CD-62P) exposed on the plasma membrane of untreated and activated platelets was monitored by flow cytometry. Secretion of platelet-derived vascular endothelial growth factor (VEGF) as well as plasminogen fragmentation and angiostatin formation by intact platelets and platelet plasma membranes were analyzed by immunoblotting. It was shown that thrombin or collagen exposure resulted in enhanced P-selectin surface expression by platelets, while Lys-form of plasminogen reduced agonist-induced platelet secretion. Lys-plasminogen, but not Glu-form, inhibited agonist-induced VEGF release from platelets. Activation of platelets significantly accelerated plasminogen cleavage and angiostatin formation. Anti-actin antibodies inhibited plasminogen fragmentation during incubation with platelet plasma membranes indicating surface-exposed actin participation  in plasminogen conversion to angiostatins. The present study uncovers a novel function of plasminogen to limit angiogenic potential of platelets via angiostatin formation and inhibition of VEGF secretion.

Fibrinolysis regulation by platelets retaining plasminogen and tissue-type plasminogen activator on their surface

T. Grinenko, О. Yusova, O. Revka, I. Patalakh, T. Yatsenko

Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: sedrickedel@gmail.com

Received: 22 July 2019; Accepted: 18 October 2019

Platelets play a key role in hemostasis as cofactors of thrombin generation, fibrin polymerization centers­, and initiators of clot retraction, while their ability to modulate clot dissolution remains less understood. The aim of this study was to investigate the interaction of plasminogen and tissue plasminogen activator with native and activated platelets, to determine the amount of plasmin generated by various activators in the presence of platelets, and the ability of platelets to modulate the rate of polymer fibrin hydrolysis. Spectrometric and immunofluorometric methods were used in the study. It was shown that intact circulating platelets carry a small amount of plasminogen on their surface, whereas thrombin-induced activation led to the exposure of plasminogen-binding sites on their plasma membrane. Activated platelets stimulated plasminogen activation by tissue plasminogen activator, urokinase, and streptokinase. Components of prothrombin complex enhanced plasminogen activation by tissue plasminogen activator on the surface of activated platelets. Model system with desAB-fibrin revealed the ability of platelets to stimulate fibrinolysis. These results suggest that the regulation of fibrinolysis by platelets is provided by the binding of plasminogen and plasminogen activators on their surface, acceleration of plasmin generation and, consequently, acceleration of the onset of fibrin lysis and reducing of the clot lifetime, which is important to maintain hemostatic balance.

Blood coagulation parameters in rats with acute radiation syndrome receiving activated carbon as a preventive remedy

V. Chernyshenko1, E. Snezhkova2, M. Mazur2, T. Chernyshenko1,
T. Platonova1, O. Sydorenko2, E. Lugovskoy1, V. Nikolaev2

1Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: bio.cherv@gmail.com;
2RE Kavetsky Institute of Experimental Pathology, Oncology and Radiobiology, National Academy of Sciences of Ukraine, Kyiv

Received: 13 December 2018; Accepted: 20 March 2019

Radiation-induced coagulopathy (RIC) is one of the major causes of death during acute radiation syndrome (ARS). The aim of this study was to characterize the responses of the hemostasis system to ARS of a moderate level on the 1st and 9th days after irradiation. We aimed to identify molecular markers of the blood coagulation system that are most affected by ARS and to estimate the enterosorption effect on the development of irradiation-induced changes. Platelet aggregation rate, activated partial thromboplastin time (APTT) and fibrinogen concentration were determined by standard methods. Level of protein C (PC) was measured using­ chromogenic substrate S2366 (p-Glu-Pro-Arg-pNa) and Agkistrodon halys halys snake venom activa­ting enzyme. Functionally inactive forms of prothrombin (FIFPs) were determined using two activators in parallel – thromboplastin or prothrombin activator from Echis multisqumatis venom. Rats of both irradia­ted groups had a higher risk of intravascular clotting in comparison to both control groups. Statistically significant shortening of clotting time in the APTT test (24 ± 4 s vs. 33 ± 5 s) and increased fibrinogen concentration (4.2 ± 0.6 mg/ml vs. 3.2 ± 0.3 mg/ml) were detected. Both parameters were normalized on the 9th day after irradiation. However the platelet count was decreased (0.3∙106 ± 0.05∙106 1/μl vs. 0.145∙106 ± 0.04∙106 1/μl) due to the impaired megakaryocytic function. The level of PC was decreased after X-ray irradiation (70 ± 10%) and partly restored on the 9th day after irradiation (87 ± 10%). Administration of activated carbon (AC) inhibited the drop in the PC concentration after X-ray irradiation (86 ± 15%) and accelerated its restoration on the 9th day (103 ± 14%). The statistically significant accumulation of FIFPs was detected in blood plasma of irradia­ted rats at the 1st and 9th days after irradiation. No FIFPs were found in any irradiated rat treated with AC. Characterization of the hemostasis system of rats that were exposed to a semilethal dose of X-rays allowed us to select parameters that can be used for monitoring of ARS development. Apart of from basic coagulation tests (APTT) and the measurement of platelet aggregation, fibrinogen and protein C level we can recommend the determination of FIFPs as a useful tool for estimation of the hemostasis response after irradiation with X-rays. This test indicates the intravascular thrombin generation and can help predict thrombotic complication or disseminated intravascular coagulation. Determination of FIFPs in blood plasma of irradia­ted rats allowed us to study the enterosorption effect on the development of irradiation-induced changes. It was shown that enterosorption with AC prevented accumulation of FIFPs which appears to be a newly discovered anti-thrombotic effect of therapy with AC. ARS influenced hemostasis by inducing thrombin generation (indicated by FIFPs generation), low-grade inflammation (indicated by PC concentration decrease) and thrombocytopenia. Enterosorption with AC minimizes inflammation and pro-coagulant processes caused by a moderate dose of X-ray irradiation. Accumulation of FIFPs can be assumed to be one of the most sensitive markers of the blood coagulation response to X-ray irradiation.

Preparation of highly-concentrated autologous platelet-rich plasma for biomedical use

V. Chernyshenko1, K. Shteinberg2, N. Lugovska1, M. Ryzhykova1,
T. Platonova1, D. Korolova1, E. Lugovskoy1

1Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: bio.cherv@gmail.com;
2‘Dr. Zapolska Clinic’, Kyiv, Ukraine

Received: 21 December 2018; Accepted: 20 March 2019

Cell therapy with platelets is a widely accepted approach for wound healing and tissue regeneration in medicine. However, with most available methods poorly concentrated platelet suspensions (up to 0.3∙106 1/µl) or suspensions of mostly inactivated or lost platelets are obtained. In this study, we aimed to develop a simple and effective method for preparing a suspension of native and resting platelets with over 1∙106 1/µl. Platelet-rich plasma (PRP) was obtained from fresh blood of healthy donors (n = 5) collected using different amounts of heparin as the anticoagulant. Samples of PRP were spun down and re-suspended in auto­logous blood plasma. Count and vitality of platelets in each sample were determined by aggregation study on the Solar AP2110 aggregometer. Platelet shape and cytoplasmic granularity that indicate the nativity of platelets were monitored on the COULTER EPICS XL Flow Cytometer. This study of aggregation of platelets in PRP obtained using various amounts of heparin allowed us to reduce final concentrations to the amount that effectively prevented clotting and did not affect platelet reactivi­ty (5 U/ml). PRP concentrated 5 times with a total concentration of cells of 1∙106 1/µl was able to be activated by adenosine diphosphate (ADP) (aggregation rate 54 ± 7%). The amount of cells with altered shape and granularity in concentrated suspension was not higher than 20%. This finding means that the platelets would still be able to release a number of growth factors and other biologically active compounds after stimulation or injection into tissue during cell therapy. The decrease in heparin concentrations also minimizes haemorrhage in the injection site supporting biomedical use of the suspension. A simple and effective method for preparation of highly-concentrated PRP (1.2∙106 1/µl) for biomedical use was developed. Aggregometry and flow cytometry proved that obtained platelets were resting and able to be activated. Being autologous, the preparation can be widely used for cell therapy without additional precautions.

Plasminogen modulates formation of reactive oxygen species in human platelets

A. A. Tykhomyrov, D. D. Zhernosekov, M. M. Guzyk, V. V. Korsa, T. V. Grinenko

Palladin Institute of Biochemistry, National Academy of Sciences of Ukraine, Kyiv;
e-mail: artem_tykhomyrov@ukr.net

Reactive oxygen species (ROS) are considered to be important signalling molecules controlling many platelet functions. ROS production has been shown to be augmented by platelet activation, however, plasminogen (Pg) has not been studied in the context of modulating intraplatelet ROS levels. The aim of this study was to investigate the ability of different Pg forms to affect platelet metabolic activity/survival and intracellular ROS production in resting and activated platelets. Platelets isolated from donor plasma were pre-treated with Glu- or Lys-Pg (1.2 µM) and activated by thrombin (1.0 NIH unit/ml) or collagen (1.25 mg/ml). MTT assay was adapted to estimate total mitochondrial dehydrogenase activity, while intracellular ROS levels were monitored with the use of H2DCF-DA probe by flow cytometry. Lys-Pg was shown to slightly, but significantly, mitigate MTT reduction (P < 0.05 vs. control platelets). Two-fold elevation in metabolic activity of platelets stimulated by thrombin as compared to untreated cells was observed. However, this activation was less exhibi­ted in the case of platelets pre-incubated with either Glu- of Lys-Pg, with a predominant effect of Lys-Pg. Unlike thrombin, collagen treatment dramatically suppressed metabolic activity of platelets by 60% compared to control (P < 0.05). Glu- or Lys-Pg pre-incubation had no effects on the activity of collagen-stimulated platelets. Two subpopulations of platelets were observed with distinct characteristics of intracellular ROS formation. Elevated ROS production was demonstrated in these populations of both thrombin- and collagen-treated platelets. Pg (Lys-form to greater extent) enhanced intracellular ROS generation in thrombin-stimulated platelets. These findings suggest that augmented ROS generation within platelets pre-treated with Pg followed by their stimulation may result in down-regulation of their survival and functional activity. This study adds to our understanding one more possible mechanism of Pg impact on the platelet function.