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  • 1.
    Basabe-Desmonts, L.
    et al.
    Biomedical Diagnostics Institute (BDI), Dublin.
    Ramstrom, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences. Royal College of Surgeons in Ireland, Dublin.
    Lopez-Alonso, A.
    Royal College of Surgeons in Ireland, Dublin.
    Somers, M.
    Biomedical Diagnostics Institute (BDI), Dublin.
    Ricco, A.J.
    Biomedical Diagnostics Institute (BDI), Dublin.
    Kenny, D.
    Royal College of Surgeons in Ireland, Dublin.
    DISPOSABLE BIOANALYTICAL MICRODEVICE FOR MONITORING THE EFFECT OF ANTI-PLATELET DRUGS2010Conference paper (Other academic)
    Abstract [en]

    We report a disposable self-powered integrated microfluidic chip that enables a rapid and simple plateletfunction assay from small samples of whole blood. The chip integrates a single-cell adhesion assay with a microfluidic platform; it enables accurate quantification of platelet adhesion, and it controls whole blood flow rate, shear stress, volume of sample, and assay time.

  • 2.
    Basabe-Desmonts, L
    et al.
    Dublin City University.
    Ramstrom, Sofia
    Royal College of Surgeons in Ireland, Dublin.
    Meade, G
    Royal College of Surgeons in Ireland (RCSI), Dublin.
    O'Neill, S
    Royal College of Surgeons in Ireland (RCSI), Dublin.
    Riaz, A
    Dublin City University.
    Lee, L P
    Dublin City University.
    Ricco, A J
    Dublin City University.
    Kenny, D
    Royal College of Surgeons in Ireland (RCSI), Dublin.
    Single-step separation of platelets from whole blood coupled with digital quantification by interfacial platelet cytometry (iPC)2010In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 26, no 18, p. 14700-14706Article in journal (Refereed)
    Abstract [en]

    We report the efficient single-step separation of individual platelets from unprocessed whole blood, enabling digital quantification of platelet function using interfacial platelet cytometry (iPC) on a chip. iPC is accomplished by the precision micropatterning of platelet-specific protein surfaces on solid substrates. By separating platelets from whole blood using specific binding to protein spots of a defined size, iPC implements a simple incubate-and-rinse approach, without sample preparation, that enables (1) the study of platelets in the physiological situation of interaction with a protein surface, (2) the choice of the number of platelets bound on each protein spot, from one to many, (3) control of the platelet-platelet distance, including the possibility to study noninteracting single platelets, (4) digital quantification (counting) of platelet adhesion to selected protein matrices, enabling statistical characterization of platelet subpopulations from meaningfully large numbers of single platelets, (5) the study of platelet receptor expression and spatial distribution, and (6) a detailed study of the morphology of isolated single platelets at activation levels that can be manipulated. To date, we have demonstrated 1-4 of the above list. Platelets were separated from whole blood using iPC with fibrinogen, von Willebrand factor (VWF), and anti-CD42b antibody printed "spots" ranging from a fraction of one to several platelet diameters (2-24 μm). The number of platelets captured per spot depends strongly on the protein matrix and the surface area of the spot, together with the platelet volume, morphology, and activation state. Blood samples from healthy donors, a May-Hegglin-anomaly patient, and a Glanzmann's Thrombasthenia patient were analyzed via iPC to confirm the specificity of the interaction between protein matrices and platelets. For example, the results indicate that platelets interact with fibrinogen spots only through the fibrinogen receptor (αIIbβ3) and, relevant to diagnostic applications, platelet adhesion correlates strongly with normal versus abnormal platelet function. A critical function of platelets is to adhere to regions of damage on blood vessel walls; in contrast to conventional flow cytometry, where platelets are suspended in solution, iPC enables physiologically relevant platelet bioassays based on platelet/protein-matrix interactions on surfaces. This technology should be inexpensive to implement in clinical assay format, is readily integrable into fluidic microdevices, and paves the way for high-throughput platelet assays from microliter volumes of whole blood.

  • 3.
    Boknäs, Niklas
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Faxälv, Lars
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Chemistry.
    Lindahl, Tomas L
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Chemistry.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Contact activation: important to consider when measuring the contribution of tissue factor-bearing microparticles to thrombin generation using phospholipid-containing reagents2014In: Journal of Thrombosis and Haemostasis, ISSN 1538-7933, E-ISSN 1538-7836, Vol. 12, no 4, p. 515-518Article in journal (Refereed)
    Abstract [en]

    Background A commercial MP reagent containing phospholipids is used for thrombin generation (TG) measurements to estimate the procoagulant activity of microparticles (MPs). Previous reports have shown that contact activation affects TG when TF levels are low, and that addition of phospholipids might augment this effect. Objectives To quantify the impact of contact activation on TG in the presence of phospholipids and low/no TF, as is the case using a commercially available MP-reagent. Methods Thrombin generation was analyzed using MP- or platelet-rich plasma (PRP)-reagent in the presence and absence of corn trypsin inhibitor and anti-TF antibodies, respectively. To quantify the impact of different experimental parameters on contact activation, microparticle-depleted plasma was analyzed in the presence of different concentrations of phospholipids, TF and/or contact activating agents (kaolin). Results Even with low contact activating blood collection tubes, substantial thrombin generation was observed with the MP-reagent, but this was completely inhibited by addition of corn trypsin inhibitor. Control experiments illustrate that the phospholipids in the reagent play a major role in enhancing TG initiated by FXIIa. Even with the PRP-reagent, which is recommended for determining the content of phospholipids from MPs, TG was partly dependent on contact activation. Conclusions Contact activation plays a major role in TG when using reagents/samples containing phospholipids but little or no tissue factor. This needs to be considered and accounted for in future clinical studies using TG to assess the procoagulant activity of MPs.

  • 4.
    Boknäs, Niklas
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Faxälv, Lars
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Chemistry.
    Sanchez Centellas, Daniel
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Wallstedt, Maria
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Grenegård, Magnus
    University of Örebro, Sweden.
    Lindahl, Tomas
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Chemistry.
    Thrombin-induced platelet activation via PAR4: pivotal role for exosite II2014In: Thrombosis and Haemostasis, ISSN 0340-6245, Vol. 112, no 3, p. 558-565Article in journal (Refereed)
    Abstract [en]

    Thrombin-induced platelet activation via PAR1 and PAR4 is an important event in haemostasis. Although the underlying mechanisms responsible for ensuring efficient PAR1 activation by thrombin have been extensively studied, the potential involvement of recognitions sites outside the active site of the protease in thrombin-induced PAR4 activation is largely unknown. In this study, we developed a new assay to assess the importance of exosite I and II for PAR4 activation with alpha- and gamma-thrombin. Surprisingly, we found that exosite II is critical for activation of PAR4. We also show that this dependency on exosite II likely represents a new mechanism, as it is unaffected by blockage of the previously known interaction between thrombin and glycoprotein Ib alpha.

  • 5.
    Boknäs, Niklas
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Faxälv, Lars
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Chemistry.
    Ström, Jakob O
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Tengvall, Pentti
    Sahlgrenska Academy, University of Gothenburg, Sweden.
    Theodorsson, Elvar
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Chemistry.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Lindahl, Tomas L
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Chemistry.
    Response: platelets do not generate activated factor XII--how inappropriate experimental models have led to misleading conclusions2014In: Blood, ISSN 0006-4971, E-ISSN 1528-0020, Vol. 124, no 10, p. 1692-1694Article in journal (Other academic)
  • 6.
    Boknäs, Niklas
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Haematology.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Chemistry. Orebro Univ, Sweden.
    Faxälv, Lars
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Chemistry.
    Lindahl, Tomas
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Chemistry.
    Flow cytometry-based platelet function testing is predictive of symptom burden in a cohort of bleeders2018In: Platelets, ISSN 0953-7104, E-ISSN 1369-1635, Vol. 29, no 5, p. 512-519Article in journal (Refereed)
    Abstract [en]

    Platelet function disorders (PFDs) are common in patients with mild bleeding disorders (MBDs), yet the significance of laboratory findings suggestive of a PFD remain unclear due to the lack of evidence for a clinical correlation between the test results and the patient phenotype. Herein, we present the results from a study evaluating the potential utility of platelet function testing using whole-blood flow cytometry in a cohort of 105 patients undergoing investigation for MBD. Subjects were evaluated with a test panel comprising two different activation markers (fibrinogen binding and P-selectin exposure) and four physiologically relevant platelet agonists (ADP, PAR1-AP, PAR4-AP, and CRP-XL). Abnormal test results were identified by comparison with reference ranges constructed from 24 healthy controls or with the fifth percentile of the entire patient cohort. We found that the abnormal test results are predictive of bleeding symptom severity, and that the greatest predictive strength was achieved using a subset of the panel, comparing measurements of fibrinogen binding after activation with all four agonists with the fifth percentile of the patient cohort (p=0.00008, hazard ratio 8.7; 95% CI 2.5-40). Our results suggest that whole-blood flow cytometry-based platelet function testing could become a feasible alternative for the investigation of MBDs. We also show that platelet function testing using whole-blood flow cytometry could provide a clinically relevant quantitative assessment of platelet-related hemostasis.

  • 7.
    Börgeson, Emma
    et al.
    Linköping University, Department of Medical and Health Sciences, Pharmacology. Linköping University, Faculty of Health Sciences.
    Lönn, Johanna
    Linköping University, Department of Medical and Health Sciences, Pharmacology. Linköping University, Faculty of Health Sciences.
    Bergström, Ida
    Linköping University, Department of Medical and Health Sciences, Cardiology. Linköping University, Faculty of Health Sciences.
    Brodin Patcha, Veronika
    Linköping University, Department of Clinical and Experimental Medicine, Medical Microbiology. Linköping University, Faculty of Health Sciences.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Nayeri, Fariba
    Linköping University, Department of Clinical and Experimental Medicine, Infectious Diseases. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Medicine, Department of Infectious Diseases in Östergötland.
    Sarndahl, Eva
    University Orebro.
    Bengtsson, Torbjörn
    Linköping University, Department of Medical and Health Sciences, Pharmacology. Linköping University, Faculty of Health Sciences.
    Lipoxin A(4) Inhibits Porphyromonas gingivalis-Induced Aggregation and Reactive Oxygen Species Production by Modulating Neutrophil-Platelet Interaction and CD11b Expression2011In: INFECTION AND IMMUNITY, ISSN 0019-9567, Vol. 79, no 4, p. 1489-1497Article in journal (Refereed)
    Abstract [en]

    Porphyromonas gingivalis is an etiological agent that is strongly associated with periodontal disease, and it correlates with numerous inflammatory disorders, such as cardiovascular disease. Circulating bacteria may contribute to atherogenesis by promoting CD11b/CD18-mediated interactions between neutrophils and platelets, causing reactive oxygen species (ROS) production and aggregation. Lipoxin A(4) (LXA(4)) is an endogenous anti-inflammatory and proresolving mediator that is protective of inflammatory disorders. The aim of this study was to investigate the effect of LXA(4) on the P. gingivalis-induced activation of neutrophils and platelets and the possible involvement of Rho GTPases and CD11b/CD18 integrins. Platelet/leukocyte aggregation and ROS production was examined by lumiaggregometry and fluorescence microscopy. Integrin activity was studied by flow cytometry, detecting the surface expression of CD11b/CD18 as well as the exposure of the high-affinity integrin epitope, whereas the activation of Rac2/Cdc42 was examined using a glutathione S-transferase pulldown assay. The study shows that P. gingivalis activates Rac2 and Cdc42 and upregulates CD11b/CD18 and its high-affinity epitope on neutrophils, and that these effects are diminished by LXA(4). Furthermore, we found that LXA(4) significantly inhibits P. gingivalis-induced aggregation and ROS generation in whole blood. However, in platelet-depleted blood and in isolated neutrophils and platelets, LXA(4) was unable to inhibit either aggregation or ROS production, respectively. In conclusion, this study suggests that LXA(4) antagonizes P. gingivalis-induced cell activation in a manner that is dependent on leukocyte-platelet interaction, likely via the inhibition of Rho GTPase signaling and the downregulation of CD11b/CD18. These findings may contribute to new strategies in the prevention and treatment of periodontitis-induced inflammatory disorders, such as atherosclerosis.

  • 8.
    Connolly-Andersen, Anne-Marie
    et al.
    Umeå University, Sweden.
    Sundberg, Erik
    Umeå University, Sweden.
    Ahlm, Clas
    Umeå University, Sweden.
    Hultdin, Johan
    Umeå University, Sweden.
    Baudin, Maria
    Umeå University, Sweden.
    Larsson, Johanna
    Umeå University, Sweden.
    Dunne, Eimear
    Royal Coll Surgeons Ireland, Ireland.
    Kenny, Dermot
    Royal Coll Surgeons Ireland, Ireland.
    Lindahl, Tomas
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Chemistry.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Nilsson, Sofie
    Umeå University, Sweden.
    Increased Thrombopoiesis and Platelet Activation in Hantavirus-Infected Patients2015In: Journal of Infectious Diseases, ISSN 0022-1899, E-ISSN 1537-6613, Vol. 212, no 7, p. 1061-1069Article in journal (Refereed)
    Abstract [en]

    Background. Thrombocytopenia is a common finding during viral hemorrhagic fever, which includes hemorrhagic fever with renal syndrome (HFRS). The 2 main causes for thrombocytopenia are impaired thrombopoiesis and/or increased peripheral destruction of platelets. In addition, there is an increased intravascular coagulation risk during HFRS, which could be due to platelet activation. Methods. Thrombopoiesis was determined by quantification of platelet counts, thrombopoietin, immature platelet fraction, and mean platelet volume during HFRS. The in vivo platelet activation was determined by quantification of soluble P-selectin (sP-selectin) and glycoprotein VI (sGPVI). The function of circulating platelets was determined by ex vivo stimulation followed by flow cytometry analysis of platelet surface-bound fibrinogen and P-selectin exposure. Intravascular coagulation during disease was determined by scoring for disseminated intravascular coagulation (DIC) and recording thromboembolic complications. Results. The levels of thrombopoietin, immature platelet fraction, and mean platelet volume all indicate increased thrombopoiesis during HFRS. Circulating platelets had reduced ex vivo function during disease compared to follow-up. Most interestingly, we observed significantly increased in vivo platelet activation in HFRS patients with intravascular coagulation (DIC and thromboembolic complications) as shown by sP-selectin and sGPVI levels. Conclusions. HFRS patients have increased thrombopoiesis and platelet activation, which contributes to intravascular coagulation.

  • 9.
    Faxälv, Lars
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Chemistry.
    Boknäs, Niklas
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Ström, Jakob
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Tengvall, Pentti
    University of Gothenburg, Gothenburg, Sweden .
    Theodorsson, Elvar
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Chemistry.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Lindahl, Tomas
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Chemistry.
    Putting polyphosphates to the test: evidence against platelet-induced activation of factor XII2013In: Blood, ISSN 0006-4971, E-ISSN 1528-0020, Vol. 122, no 23, p. 3818-3824Article in journal (Refereed)
    Abstract [en]

    The recent claim that stimulated platelets activate the intrinsic pathway of coagulation by the release of polyphosphates has been considered a breakthrough in hemostasis research. In little more than 3 years, the original publication by Muller et al has been cited greater than100 times. However, none of the citing articles has sought to independently validate this potentially paradigm-shifting concept. To this end, we performed extensive experimentation in vitro and in vivo in an attempt to verify the claim that factor XII (FXII) is primarily activated by stimulated platelets. In contrast to the original assertion, platelet-derived polyphosphates were found to be weak activators of FXII, with a FXIIa-generating activity of less than10% compared with equivalent concentrations of kaolin. Using different coagulation assays, it was shown that platelet contribution to whole blood coagulation was unrelated to the generation of activated FXII in vitro. Additionally, key results used to verify the hypothesis in the original study in vivo were found to be irreproducible. We conclude that platelet-derived polyphosphates are not physiologically relevant activators of FXII.

  • 10.
    Faxälv, Lars
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Chemistry.
    Ramström, Sofia
    Molecular and Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland.
    Soutukorva, Kristina
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
    Tengvall, Pentti
    Linköping University, Department of Physics, Chemistry and Biology, Applied Physics. Linköping University, The Institute of Technology.
    Lindahl, Tomas L.
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Chemistry.
    The role of coagulation factor XII in propagation of coagulationManuscript (preprint) (Other academic)
    Abstract [en]

    The physiological relevance and function of coagulation factor XII (FXII), the first zymogen in the intrinsic pathway, has for a long time been a matter of debate. The aim of this study was to shed some light on the role of factor XII in thrombus formation with a focus on its effect during the propagation phase of coagulation. In order to study propagation of coagulation we utilized a new imaging method to measure propagation rates from an activating surface in both platelet-free plasma and platelet-rich plasma. The most essential results revealed that both FXII and its substrate FXI are located on the surface of activated platelets. The surface of preexisting clots does not support coagulation in a FXII dependent manner. However, we found strong evidence for an accelerated propagation of tissue factor initiated coagulation when contact activation of FXII simultaneously occurred in the proximity. In vivo sources for contact activation may be exposed subendothelial collagen as well as soluble and cell derived poly-anions. If such in vivo contact activation of FXII occurs, even though moderate, it could contribute to in vivo thrombus growth rate and thus be of pathophysiological importance.

  • 11.
    Grenegård, Magnus
    et al.
    Linköping University, Department of Medicine and Health Sciences, Pharmacology . Linköping University, Faculty of Health Sciences.
    Vretenbrant-Öberg, Karin
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Nylander, Martina
    Linköping University, Department of Medicine and Health Sciences, Pharmacology . Linköping University, Faculty of Health Sciences.
    Désilets, Stéphanie
    Linköping University, Department of Medicine and Health Sciences, Pharmacology . Linköping University, Faculty of Health Sciences.
    Lindström, Eva G
    Linköping University, Department of Medicine and Health Sciences, Pharmacology . Linköping University, Faculty of Health Sciences.
    Larsson, Anders
    Department of Medical Sciences, University Hospital, Uppsala SE-75105, Sweden.
    Ramström, Ida
    Linköping University, Department of Medicine and Health Sciences, Pharmacology . Linköping University, Faculty of Health Sciences.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Lindahl, Tomas L
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Chemistry.
    The ATP-gated P2X1 receptor plays a pivotal role in activation of aspirin-treated platelets by thrombin and epinephrine2008In: Journal of Biological Chemistry, ISSN 0021-9258, E-ISSN 1083-351X, Vol. 283, no 27, p. 18493-18504Article in journal (Refereed)
    Abstract [en]

    Human platelets express protease-activated receptor 1 (PAR1) and PAR4 but limited data indicate for differences in signal transduction. We studied the involvement of PAR1 and PAR4 in the cross-talk between thrombin and epinephrine. The results show that epinephrine acted via alpha(2A)-adrenergic receptors to provoke aggregation, secretion, and Ca(2+) mobilization in aspirin-treated platelets pre-stimulated with subthreshold concentrations of thrombin. Incubating platelets with antibodies against PAR4 or the PAR4-specific inhibitor pepducin P4pal-i1 abolished the aggregation. Furthermore, platelets pre-exposed to the PAR4-activating peptide AYPGKF, but not to the PAR1-activating peptide SFLLRN, were aggregated by epinephrine, whereas both AYPGKF and SFLLRN synergized with epinephrine in the absence of aspirin. The roles of released ATP and ADP were elucidated by using antagonists of the purinergic receptors P2X(1), P2Y(1), and P2Y(12) (i.e. NF449, MRS2159, MRS2179, and cangrelor). Intriguingly, ATP, but not ADP, was required for the epinephrine/thrombin-induced aggregation. In Western blot analysis, a low concentration of AYPGKF, but not SFLLRN, stimulated phosphorylation of Akt on serine 473. Moreover, the phosphatidyl inositide 3-kinase inhibitor LY294002 antagonized the effect of epinephrine combined with thrombin or AYPGKF. Thus, in aspirin-treated platelets, PAR4, but not PAR1, interacts synergistically with alpha(2A)-adrenergic receptors, and the PI3-kinase/Akt pathway is involved in this cross-talk. Furthermore, in PAR4-pretreated platelets, epinephrine caused dense granule secretion, and subsequent signaling from the ATP-gated P2X(1)-receptor and the alpha(2A)-adrenergic receptor induced aggregation. These results suggest a new mechanism that has ATP as a key element and circumvents the action of aspirin on epinephrine-facilitated PAR4-mediated platelet activation.

  • 12.
    Lindahl, Tomas L
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Chemistry.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences. Royal College of Surgeons in Ireland, Irland.
    Methods for evaluation of platelet function.2009In: Transfusion and apheresis science, ISSN 1473-0502, E-ISSN 1878-1683, Vol. 41, no 2, p. 121-125Article in journal (Refereed)
    Abstract [en]

    There are a multitude of platelet function tests available, reflecting the complex nature of the platelet in haemostasis. No simple single test will ever cover all aspects of platelet function. Some tests focus on the aggregation of platelets, for example aggregometry, other on the swelling in response to hypotonic solutions, i.e. the well-known hypotonic shock response, or adhesion or coagulation and clot retraction, for example thromboelastography. In general there is a lack of clinical studies showing a predictive value of analysis of platelet concentrates.

  • 13.
    Lindahl, Tomas
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Chemistry.
    Macwan, Ankit
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Protease-activated receptor 4 is more important than protease-activated receptor 1 for the thrombin-induced procoagulant effect on platelets in JOURNAL OF THROMBOSIS AND HAEMOSTASIS, vol 14, issue 8, pp 1639-16412016In: Journal of Thrombosis and Haemostasis, ISSN 1538-7933, E-ISSN 1538-7836, Vol. 14, no 8, p. 1639-1641Article in journal (Other academic)
    Abstract [en]

    n/a

  • 14.
    Lindahl, Tomas
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Chemistry.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Boknäs, Niklas
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Faxälv, Lars
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Chemistry.
    Caveats in studies of the physiological role of polyphosphates in coagulation2016In: Biochemical Society Transactions, ISSN 0300-5127, E-ISSN 1470-8752, Vol. 44, p. 35-39Article, review/survey (Refereed)
    Abstract [en]

    Platelet-derived polyphosphates (polyP), stored in dense granule and released upon platelet activation, have been claimed to enhance thrombin activation of coagulation factor XI (FXI) and to activate FXII directly. The latter claim is controversial and principal results leading to these conclusions are probably influenced by methodological problems. It is important to consider that low-grade contact activation is initiated by all surfaces and is greatly amplified by the presence of phospholipids simulating the procoagulant membranes of activated platelets. Thus, proper use of inhibitors of the contact pathway and a careful choice of materials for plates and tubes is important to avoid artefacts. The use of phosphatases used to degrade polyP has an important drawback as it also degrades the secondary activators ADP and ATP, which are released from activated platelets. In addition, the use of positively charged inhibitors, such as polymyxin B, to inhibit polyP in platelet-rich plasma and blood is problematic, as polymyxin B also slows coagulation in the absence of polyP. In conclusion we hope awareness of the above caveats may improve research on the physiological roles of polyP in coagulation. © 2016 Authors; published by Portland Press Limited.

  • 15.
    Lopez-Alonso, Ana
    et al.
    Royal Coll Surgeons Ireland, Ireland .
    Jose, Bincy
    Dublin City University, Ireland .
    Somers, Martin
    Dublin City University, Ireland .
    Egan, Karl
    Royal Coll Surgeons Ireland, Ireland .
    Foley, David P.
    Beaumont Hospital, Ireland .
    Ricco, Antonio J.
    Dublin City University, Ireland .
    Ramstrom, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences. Royal Coll Surgeons Ireland, Ireland .
    Basabe-Desmonts, Lourdes
    Dublin City University, Ireland .
    Kenny, Dermot
    Royal Coll Surgeons Ireland, Ireland .
    Individual Platelet Adhesion Assay: Measuring Platelet Function and Antiplatelet Therapies in Whole Blood via Digital Quantification of Cell Adhesion2013In: Analytical Chemistry, ISSN 0003-2700, E-ISSN 1520-6882, Vol. 85, no 13, p. 6497-6504Article in journal (Refereed)
    Abstract [en]

    Widespread monitoring of platelet function and the effect of antiplatelet drugs will improve outcomes in cardiovascular patients, but platelet function testing is not routine in clinical practice. We report a rapid, accurate methodology to quantify platelet-protein interactions: a microarray of contact-printed 6-mu m fibrinogen dots on a transparent substrate binds platelets from whole blood, one platelet per dot. The fractional occupancy of an array of fibrinogen dots after a predefined incubation time quantitatively assays platelet adhesion to the protein matrix. We demonstrate this technique by measurement of platelet adhesion to fibrinogen as a means to quantify the effect of the P2Y(12) and alpha IIb beta 3 receptor inhibitors cangrelor and abciximab, respectively, both in vitro-by incubating the drug with a freshly drawn blood sample-and in blood from patients treated with antiplatelet agents. The effects of single- and dual-antiplatelet therapy are also assessed. Results from this platelet-binding assay are well correlated with standard techniques including flow cytometry and light transmission aggregometry. This assay technology, readily integrated with microfluidic platforms, is generally applicable to the assay of cell-protein interactions and promises more effective, rapid assay of drug effects in cardiovascular disease patients.

  • 16.
    Macwan, Ankit
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Chemistry. Linköping University, Faculty of Medicine and Health Sciences.
    Boknäs, Niklas
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Chemistry. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Surgery, Orthopaedics and Cancer Treatment, Department of Haematology.
    Ntzouni, Maria
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Chemistry. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Chemistry. Orebro Univ, Sweden.
    Gibbins, Jonathan M.
    Univ Reading, England.
    Faxälv, Lars
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Chemistry. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Chemistry.
    Lindahl, Tomas
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Chemistry. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Chemistry.
    Gradient-dependent inhibition of stimulatory signaling from platelet G protein-coupled receptors2019In: Haematologica, ISSN 0390-6078, E-ISSN 1592-8721, Vol. 104, no 7Article in journal (Refereed)
    Abstract [en]

    As platelet activation is an irreversible and potentially harmful event, platelet stimulatory signaling must be tightly regulated to ensure the filtering-out of inconsequential fluctuations of agonist concentrations in the vascular milieu. Herein, we show that platelet activation via G protein-coupled receptors is gradient-dependent, i.e., determined not only by agonist concentrations per se but also by how rapidly concentrations change over time. We demonstrate that gradient-dependent inhibition is a common feature of all major platelet stimulatory G protein-coupled receptors, while platelet activation via the non-G protein-coupled receptor glycoprotein VI is strictly concentration-dependent. By systematically characterizing the effects of variations in temporal agonist concentration gradients on different aspects of platelet activation, we demonstrate that gradient-dependent inhibition of protease-activated receptors exhibits different kinetics, with platelet activation occurring at lower agonist gradients for protease-activated receptor 4 than for protease-activated receptor 1, but shares a characteristic bimodal effect distribution, as gradient-dependent inhibition increases over a narrow range of gradients, below which aggregation and granule secretion is effectively shut off. In contrast, the effects of gradient-dependent inhibition on platelet activation via adenosine diphosphate and thromboxane receptors increase incrementally over a large range of gradients. Furthermore, depending on the affected activation pathway, gradient-dependent inhibition results in different degrees of refractoriness to subsequent autologous agonist stimulation. Mechanistically, our study identifies an important role for the cyclic adenosine monophosphate-dependent pathway in gradient-dependent inhibition. Together, our findings suggest that gradient-dependent inhibition may represent a new general mechanism for hemostatic regulation in platelets.

  • 17.
    Milovanovic, Micha
    et al.
    Linköping University, Department of Social and Welfare Studies, Health, Activity, Care. Linköping University, Faculty of Health Sciences.
    Lysen, J.
    Linköping University, Department of Medicine and Health Sciences, Cardiology . Linköping University, Faculty of Health Sciences.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Lindahl, Tomas
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry.
    Richter, Arina
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Cardiology . Östergötlands Läns Landsting, Heart Centre, Department of Cardiology.
    Järemo, Petter
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Medicine and Health Sciences, Cardiology . Östergötlands Läns Landsting, Local Health Care Services in the East of Östergötland, Department of Internal Medicine VHN.
    Identification of low-density plate and elevated let populations with increased reactivity alpha-granule content2003In: Thrombosis Research, ISSN 0049-3848, E-ISSN 1879-2472, Vol. 111, no 01-Feb, p. 75-80Article in journal (Refereed)
    Abstract [en]

    The present study examines biochemical and functional characteristics of platelet density subpopulations together with their ability to mobilise intracellular fibrinogen when activated. Platelets from three healthy volunteers were investigated. The total platelet population was separated according to density in a linear Percoll(TM) gradient in a plasma-free milieu containing EDTA that binds soluble Ca2+. Subsequently, platelets from each individual were divided according to density into 11 or 12 aliquots. In all fractions, we determined platelet count, intracellular P-selectin and the ADP-evoked platelet fibrinogen binding as a measure of platelet reactivity together with the platelet dense body content. The work demonstrates that platelets use stored intracellular fibrinogen when activated. It also shows that the platelet-fibrinogen binding can be initiated in a surrounding depleted of Ca2+ and fibrinogen. Moreover, the study demonstrates subpopulations of light platelets having increased reactivity and more alpha-granules but less dense bodies. The biological significance of the findings needs to be elucidated. (C) 2003 Elsevier Ltd. All rights reserved.

  • 18.
    Nylander, Martina
    et al.
    Linköping University, Department of Medical and Health Sciences, Pharmacology. Linköping University, Faculty of Health Sciences.
    Fälker, Knut
    Linköping University, Department of Clinical and Experimental Medicine. Linköping University, Faculty of Health Sciences.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Grenegård, Magnus
    Linköping University, Department of Medical and Health Sciences, Pharmacology. Linköping University, Faculty of Health Sciences.
    Lindahl, Tomas
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Diagnostics, Department of Clinical Chemistry.
    Release of ADP or PAR4 Activation is Required to Sustain Thrombin-induced Platelet AggregationManuscript (preprint) (Other academic)
    Abstract [en]

    Thrombin activates human platelets through cleavage of two G-protein-coupled proteaseactivatedreceptors (PARs) denoted PAR1 and PAR4. The aim of this study was to investigatedifferences in PAR1 and PAR4 signaling regarding formation and stability of plateletaggregates. We show that weak PAR1-mediated aggregation is reversible, whereas PAR4-mediated aggregation, weak or strong, is always sustained. PAR1-induced plateletaggregation is decreased and more reversible in the presence of the P2Y12 antagonistcangrelor. However, the effects by cangrelor can be concentration-dependently reversed byconcomitant PAR4 activation in a PI3-kinase-dependent manner. In contrast; in PAR4-APstimulated platelets, aggregation is reduced by cangrelor or inhibition of PI3-kinase byLY294002 but remains irreversible. However, a combined inhibition of PI3-K and P2Y12results in reduced and reversible aggregation. In the light of recently published data on PAR1desensitization, we suggest that the physiological role of the differences between PAR1 andPAR4 activation on aggregate and clot stability could be to fine-tune the response tothrombin. A repeated or continuous very low thrombin generation will desensitize PAR1 andeven if small platelet aggregates are formed they will dissolve, preventing inappropriatethrombus formation. At higher concentrations of thrombin, PAR4 will become activatedabrogating desensitization of PAR1 and enforcing stability of platelet aggregates.

  • 19.
    Nylander, Martina
    et al.
    Linköping University, Department of Medical and Health Sciences, Pharmacology. Linköping University, Faculty of Health Sciences.
    Osman, Abdimajid
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Chemistry.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Åklint, Emma
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Larsson, Anders
    Department of Medical Sciences, University Hospital, Uppsala, Sweden.
    Lindahl, Tomas
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Chemistry.
    The role of thrombin receptors PAR1 and PAR4 for PAI-1 storage, synthesis and secretion by human platelets2012In: Thrombosis Research, ISSN 0049-3848, E-ISSN 1879-2472, Vol. 129, no 4, p. E51-E58Article in journal (Refereed)
    Abstract [en]

    INTRODUCTION:

    Arterial thrombi contain more platelets than venous thrombi and are more resistant to fibrinolysis. This resistance could partly be due to plasminogen activator inhibitor 1 (PAI-1) secreted by platelets. The aim of this study was to elucidate differences between thrombin receptors protease-activated receptor (PAR) 1 and 4 and platelet storage, secretion and synthesis of platelet PAI-1, as compared to other platelet α-granule proteins such as VEGF and endostatin.

    MATERIALS AND METHODS:

    Human isolated platelets were incubated with thrombin (0.5U/ml), PAR1-activating peptide (AP) (0.4-30μM) or PAR4-AP (1.5-300μM) for up to 24hours. ELISA, western blot and fluorescence microscopy were used to measure secretion, contents and localization of PAI-1, VEGF and endostatin.

    RESULTS:

    Our results show that PAI-1 and VEGF might be co-localized and that endostatin does not co-localize with either PAI-1 or VEGF. PAI-1 and VEGF show a similar secretion pattern, being more sensitive to low grade PAR1 activation, but secretion was also observed with higher concentrations of PAR4-APs. PAI-1 is secreted in an active form. PAI-1 mRNA was found in platelets, and elevated levels of PAI-1 were detected after 24hours incubation of platelets.

    CONCLUSIONS:

    PAI-1 and VEGF, but not endostatin, might be stored in the same α-granule in human platelets. PAI-1 and VEGF also show a similar secretion pattern, being more sensitive to PAR1 than to PAR4 activation, but the secretion is not exclusively selective. Our results also show that platelet PAI-1 is increased if incubated for 24hours, both with addition of PAR1-activating peptide and without activation, which could indicate de novo synthesis.

  • 20.
    Nylander, Sven
    et al.
    Department of Molecular Pharmacology, Preclinical R and D, AstraZeneca R and D, Mölndal, Sweden.
    Mattsson, Christer
    Department of Molecular Pharmacology, Preclinical R and D, AstraZeneca R and D, Mölndal, Sweden.
    Ramström, Sofia
    Linköping University, Department of Biomedicine and Surgery, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Lindahl, Tomas
    Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Synergistic action between inhibition of P2Y12/P2Y1 and P2Y12/thrombin in ADP- and thrombin-induced human platelet activation2004In: British Journal of Pharmacology, ISSN 0007-1188, E-ISSN 1476-5381, Vol. 142, no 8, p. 1325-1331Article in journal (Refereed)
    Abstract [en]
    • The objective of this study was to investigate if there is a synergistic effect of a combination of P2Y12 and P2Y1 inhibition and P2Y12 and thrombin inhibition, on ADP- and thrombin-induced platelet activation, respectively. The rationale being that these combinations will cause a concurrent inhibition of both Gαq and Gαi signalling.

    • Blood from healthy volunteers was preincubated with AR-C69931MX, a reversible P2Y12 antagonist; MRS2179, a reversible P2Y1 antagonist; or melagatran, a direct reversible thrombin inhibitor; alone or in various combinations prior to activation with ADP or thrombin. Platelet function in whole blood was assessed by flow cytometry using the antibody PAC-1 to estimate the expression of active αIIbβ3 (the fibrinogen receptor GPIIb/IIIa). A synergistic effect was evaluated by comparing the concentrations in the different combinations with those of corresponding equipotent concentrations of each single inhibitor alone. The equipotent single concentrations were experimentally obtained from concentration response curves performed in parallel.

    • A synergistic effect regarding inhibition of ADP-induced platelet activation (10 μM) was obtained with different combinations of AR-C69931MX and MRS2179.

    • Inhibition of thrombin-induced platelet activation (2 nM) with combinations of AR-C69931MX and the thrombin inhibitor melagatran did also result in a strong synergistic effect.

    • To our knowledge, this is the first time that data supporting a synergistic effect has been published for the inhibitor combinations described.

    • Whether this synergistic effect in vitro also results in an improved antithrombotic effect in vivo with or without an increased risk of bleeding remains to be studied in well-conducted clinical studies.

  • 21.
    Nylander, Sven
    et al.
    Preclinical R&D, Department of Molecular Pharmacology, AstraZeneca R&D Mölndal, Sweden.
    Mattsson, Christer
    Preclinical R&D, Department of Molecular Pharmacology, AstraZeneca R&D Mölndal, Sweden.
    Ramström, Sofia
    Linköping University, Department of Biomedicine and Surgery, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Lindahl, Tomas
    Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    The relative importance of the ADP receptors, P2Y12 and P2Y1, in thrombin-induced platelet activation2003In: Thrombosis Research, ISSN 0049-3848, E-ISSN 1879-2472, Vol. 111, no 1-2, p. 65-73Article in journal (Refereed)
    Abstract [en]

    The objective of this study was to test the relative importance of the two adenosine diphosphate (ADP) receptors P2Y1 and P2Y12 in thrombin-induced platelet activation using specific receptor antagonists. Blood from healthy volunteers was incubated with MRS2179, a reversible P2Y1 antagonist, or AR-C69931, a reversible P2Y12 antagonist prior to activation with different concentrations of ADP or thrombin. Platelet function in whole blood was assayed by flow cytometry using the antibody PAC-1 to estimate the expression of conformational active αIIbβ3, the fibrinogen receptor. Complete inhibition of P2Y12 or P2Y1 abolished the ADP response, but only inhibition of P2Y12 reduced the thrombin-induced response. The relative inhibition of the thrombin response by complete inhibition of P2Y12 was most pronounced at thrombin concentrations just enough for complete PAR1 cleavage, which is sufficient to release all ADP, giving 70–86% inhibition. Above this concentration, the relative importance of P2Y12 inhibition decreased due to activation of ADP independent pathways. This study supports P2Y12 as a drug target compared with P2Y1.

  • 22.
    Olsson, Anki
    et al.
    Linköping University, Department of Medical and Health Sciences. Linköping University, Faculty of Medicine and Health Sciences. Department of Health Science, Karlskrona, Blekinge Hospital, Karlskrona, Sweden.
    Alfredsson, Joakim
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Cardiology in Linköping.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Chemistry.
    Svedjeholm, Rolf
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Thoracic and Vascular Surgery.
    Kenny, Dermot
    Clinical Research Centre, Royal College of Surgeons in Ireland, Dublin, Ireland.
    Håkansson, Eric
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Thoracic and Vascular Surgery.
    Berglund, Johan Sanmartin
    Department of Health Science, Karlskrona, Sweden.
    Berg, Sören
    Linköping University, Department of Medical and Health Sciences, Division of Cardiovascular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Heart and Medicine Center, Department of Thoracic and Vascular Surgery.
    Better platelet function, less fibrinolysis and less hemolysis in re-transfused residual pump blood with the Ringer's chase technique: a randomized pilot study2018In: Perfusion, ISSN 0267-6591, E-ISSN 1477-111X, Vol. 33, no 3, p. 185-193Article in journal (Refereed)
    Abstract [en]

    INTRODUCTION: Residual pump blood from the cardiopulmonary bypass (CPB) circuit is often collected into an infusion bag (IB) and re-transfused. An alternative is to chase the residual blood into the circulation through the arterial cannula with Ringer's acetate. Our aim was to assess possible differences in hemostatic blood quality between these two techniques.

    METHODS: Forty adult patients undergoing elective coronary artery bypass graft surgery with CPB were randomized to receive the residual pump blood by either an IB or through the Ringer's chase (RC) technique. Platelet activation and function (impedance aggregometry), coagulation and hemolysis variables were assessed in the re-transfused blood and in the patients before, during and after surgery. Results are presented as median (25-75 quartiles).

    RESULTS: Total hemoglobin and platelet levels in the re-transfused blood were comparable with the two methods, as were soluble platelet activation markers P-selectin and soluble glycoprotein VI (GPVI). Platelet aggregation (U) in the IB blood was significantly lower compared to the RC blood, with the agonists adenosine diphosphate (ADP) 24 (10-32) vs 46 (33-65), p<0.01, thrombin receptor activating peptide (TRAP) 50 (29-73) vs 69 (51-92), p=0.04 and collagen 24 (17-28) vs 34 (26-59), p<0.01. The IB blood had higher amounts of free hemoglobin (mg/L) (1086 (891-1717) vs 591(517-646), p<0.01) and D-dimer 0.60 (0.33-0.98) vs 0.3 (0.3-0.48), p<0.01. Other coagulation variables showed no difference between the groups.

    CONCLUSIONS: The handling of blood after CPB increases hemolysis, impairs platelet function and activates coagulation and fibrinolysis. The RC technique preserved the blood better than the commonly used IB technique.

  • 23.
    Peng, Xiang
    et al.
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences. Jinan University, Guangdong, China.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Kurz, Tino
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences.
    Grenegård, Magnus
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences. University of Örebro, Sweden.
    Segelmark, Mårten
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Heart and Medicine Center, Department of Nephrology.
    The neutrophil serine protease PR3 induces shape change of platelets via the Rho/Rho kinase and Ca2+ signaling pathways2014In: Thrombosis Research, ISSN 0049-3848, E-ISSN 1879-2472, Vol. 134, no 2, p. 418-425Article in journal (Refereed)
    Abstract [en]

    Introduction: Proteinase 3 (PR3) is released from neutrophil azurophilic granules and exerts complex effects on the inflammatory process. PR3 catalyzes the degradation of a number of macromolecules, but the consequences on blood cells are less well defined. In the present study, the effect of PR3 on human platelets was thoroughly investigated. Methods: The experiments were performed on washed platelets freshly isolated from blood donated by healthy human volunteers. Platelets shape change and aggregation was measured on a Chrono-Log aggregometer. The phosphorylated form of MYPT1 was visualized by immunostaining. Platelet activation was further evaluated by flow cytometry. Results: PR3 induced platelet shape change but not aggregation. Flow cytometry analysis showed that PR3 induced no P-selectin expression or binding of fibrinogen to the platelets, and it did not change the activation in response to PAR1- or PAR4-activating peptides or to thrombin. Furthermore, Fura-2 measurement and immuno-blotting analysis, respectively, revealed that PR3 stimulated small intracellular Ca2+ mobilization and Thr696-specific phosphorylation of the myosin phosphatase target subunit 1 (MYPT1). Separate treatment of platelets with the Rho/Rho kinase inhibitor Y-27632 and the intracellular Ca2+ chelator BAPTA/AM reduced the shape change induced by PR3 whereas concurrent treatment completely inhibited it. Conclusion: The data shows that the neutrophil protease PR3 is a direct modulator of human platelets and causes shape change through activation of the Rho/Rho kinase and Ca2+ signaling pathways. This finding highlights an additional mechanism in the complex interplay between neutrophils and platelets.

  • 24.
    Ramström, A Sofia
    et al.
    Linköping University, Department of Biomedicine and Surgery, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Fagerberg, I.
    Linköping University, Department of Biomedicine and Surgery, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Lindahl, Tomas
    Linköping University, Department of Biomedicine and Surgery, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    A flow cytometric assay for the study of dense granule storage and release in human platelets1999In: Platelets, ISSN 0953-7104, E-ISSN 1369-1635, Vol. 10, no 2-3, p. 153-158Article in journal (Refereed)
    Abstract [en]

    The clinical manifestations of platelet dense (δ) granule defects are easy bruising, as well as epistaxis and bleeding after delivery, tooth extractions and surgical procedures. The observed symptoms may be explained either by a decreased number of granules or by a defect in the uptake/release of granule contents. We have developed a method to study platelet dense granule storage and release. The uptake of the fluorescent marker, mepacrine, into the platelet dense granule was measured using flow cytometry. The platelet population was identified by the size and binding of a phycoerythrin-conjugated antibody against GPIb. Cells within the discrimination frame were analysed for green (mepacrine) fluorescence. Both resting platelets and platelets previously stimulated with collagen and the thrombin receptor agonist peptide SFLLRN was analysed for mepacrine uptake. By subtracting the value for mepacrine uptake after stimulation from the value for uptake without stimulation for each individual, the platelet dense granule release capacity could be estimated. Whole blood samples from 22 healthy individuals were analysed. Mepacrine incubation without previous stimulation gave mean fluorescence intensity (MFI) values of 83±6 (mean ± 1 SD, range 69–91). The difference in MFI between resting and stimulated platelets was 28±7 (range 17–40). Six members of a family, of whom one had a known δ-storage pool disease, were analysed. The two members (mother and son) who had prolonged bleeding times also had MFI values disparate from the normal population in this analysis. The values of one daughter with mild bleeding problems but a normal bleeding time were in the lower part of the reference interval.

  • 25.
    Ramström, Sofia
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of clinical chemistry.
    Clotting time analysis of citrated blood samples is strongly affected by the tube used for blood sampling2005In: Blood Coagulation and Fibrinolysis, ISSN 0957-5235, E-ISSN 1473-5733, Vol. 16, no 6, p. 447-452Article in journal (Refereed)
    Abstract [en]

    Our aim was to establish whether differences in clotting times for recalcified blood and plasma samples might be explained by the use of different blood collection tubes. Samples obtained from different plastic vacuum tubes were recalcified and clotting times determined by free oscillation rheometry. The clotting times for blood collected in Vacutainer (Becton Dickinson, Rutherford, New Jersey, USA) or Vacuette (Greiner Bio-One, Kremsmünster, Austria) tubes decreased with time, with maximal effect after 30 min. Blood from Monovette (Sarstedt, Nümbrecht, Germany) tubes displayed longer clotting times, which did not decrease with time. Clotting times for plasma prepared after 1 h storage in Vacutainer or Vacuette tubes were unaffected by subsequent addition of corn trypsin inhibitor to inhibit factor XIIa, although an antibody against factor XI prolonged the clotting time markedly. In Monovette plasma, both corn trypsin inhibitor and anti-factor XI effectively prolonged the clotting time. When corn trypsin inhibitor or anti-factor XI was added to the tubes before blood collection, but both additions clearly prolonged the clotting times in all types of tubes, even though corn trypsin inhibitor was less effective in whole blood. Antibodies against human tissue factor did not affect the clotting times. The amounts of platelet or leukocyte microparticles in plasma were low and similar in all tubes. This indicates that blood collection in Vacutainer or Vacuette tubes induces a rapid activation of factor XII and factor XI.

  • 26.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Point-of-Care coagulation testing2008In: Klinisk Biokemi i Norden, ISSN 1101-2013, no Special issue on Coagulation, p. 76-83Article, review/survey (Refereed)
  • 27.
    Ramström, Sofia
    Linköping University, Department of Biomedicine and Surgery, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    The role of platelets in whole blood coagulation2003Doctoral thesis, comprehensive summary (Other academic)
    Abstract [en]

    The body's first line of defence against bleeding is the platelets, small cell fragments with multiple roles in the coagulation process. The platelets are patrolling our blood vessels, looking for damage in the endothelial cell layer, to which they attach and transform, recruit more platelets and assemble the plasma coagulation proteases on their surfaces. Cleavage of the plasma coagulation factors then leads to the formation of a fibrin network sealing the damage.

    This thesis present studies of the role of platelets in whole blood coagulation, using methods which enable studies in a whole blood environment, flow cytometry and free oscillation rheometry (FOR). FOR proved to be equivalent in accuracy to visual inspection in detecting clotting, but allowing for simultaneous analysis of a large number of blood samples. A flow cytometry method for measuring the contents and release capacity of platelet dense granules was also developed.

    FOR was used to study platelets in coagulation. A quick removal of all blood cells was shown to be enough to keep the plasma anticoagulated. Activation of platelets by addition of collagen or a thrombin receptor agonist peptide (TRAP-6) shortened the whole blood clotting time, indicating the importance of platelets for the acceleration of coagulation. Inhibitors of the platelet fibrinogen receptor prevented clot retraction and prolonged the clotting time with TRAP-6. In collagen-stimulated samples, however, MK-852 accelerated clotting but delayed completion of clotting, while abciximab prolonged both clotting time and completion of clotting. Inhibitors to the platelet ADP receptors prolonged the clotting time, but did not affect the coagulum elasticity or the resistance against fibrinolysis. The same results were seen in a patient with a defective release of dense granule contents (which normally includes ADP). When comparing the platelet surface exposure of phosphatidylserine (PS) with the actual shortening of the clotting time, we found that despite the large decrease in clotting times seen with collagen or TRAP-6, only low numbers of PS-exposing platelets were detected. Induction of a similar PS exposure by the calcium ionophore A23187 could not decrease the clotting times to the same extent, indicating that PS exposure is only one of the mechanisms involved in platelet binding of plasma coagulation factors. Addition of annexin V, a substance that binds to PS, hampered, but could not abolish, coagulation. Artificial PS-containing lipid vesicles could not replace platelets, as they did not affect the coagulation of blood or plasma. To see which coagulation pathway that was involved in platelet dependent blood coagulation, inhibitors to factor XII or tissue factor (TF) were added to the blood prior to the platelet agonist Inhibition of factor xn increased the clotting time from about 10 to 15 minutes. Inhibition of TF was without effect. The results harmonised with the coagulation behaviour of blood congenitally deficient in factor XII or VII. Inhibition of factor XI caused a two to three fold increase in clotting time.

    We conclude that plasma does not necessarily coagulate if all blood cells are quickly removed. Activated platelets accelerate the coagulation of native whole blood ex vivo in a process which is independent of TF. Platelet PS, factor XI and factor XII all promote this coagulation, but are not essential This suggests that there might exist a platelet dependent blood coagulation pathway differing from the established pathways. Drugs affecting the platelet fibrinogen and ADP receptors affect the coagulation of the blood samples which might be detected by FOR. Our studies suggest the possibility of using FOR to measure the "platelet reactivity potential".

    List of papers
    1. A flow cytometric assay for the study of dense granule storage and release in human platelets
    Open this publication in new window or tab >>A flow cytometric assay for the study of dense granule storage and release in human platelets
    1999 (English)In: Platelets, ISSN 0953-7104, E-ISSN 1369-1635, Vol. 10, no 2-3, p. 153-158Article in journal (Refereed) Published
    Abstract [en]

    The clinical manifestations of platelet dense (δ) granule defects are easy bruising, as well as epistaxis and bleeding after delivery, tooth extractions and surgical procedures. The observed symptoms may be explained either by a decreased number of granules or by a defect in the uptake/release of granule contents. We have developed a method to study platelet dense granule storage and release. The uptake of the fluorescent marker, mepacrine, into the platelet dense granule was measured using flow cytometry. The platelet population was identified by the size and binding of a phycoerythrin-conjugated antibody against GPIb. Cells within the discrimination frame were analysed for green (mepacrine) fluorescence. Both resting platelets and platelets previously stimulated with collagen and the thrombin receptor agonist peptide SFLLRN was analysed for mepacrine uptake. By subtracting the value for mepacrine uptake after stimulation from the value for uptake without stimulation for each individual, the platelet dense granule release capacity could be estimated. Whole blood samples from 22 healthy individuals were analysed. Mepacrine incubation without previous stimulation gave mean fluorescence intensity (MFI) values of 83±6 (mean ± 1 SD, range 69–91). The difference in MFI between resting and stimulated platelets was 28±7 (range 17–40). Six members of a family, of whom one had a known δ-storage pool disease, were analysed. The two members (mother and son) who had prolonged bleeding times also had MFI values disparate from the normal population in this analysis. The values of one daughter with mild bleeding problems but a normal bleeding time were in the lower part of the reference interval.

    Place, publisher, year, edition, pages
    Informa Healthcare, 1999
    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-25010 (URN)10.1080/09537109909169179 (DOI)9431 (Local ID)9431 (Archive number)9431 (OAI)
    Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2017-12-13
    2. Clotting time by free oscillation rheometry and visual inspection and a viscoelastic description of the clotting phenomenon
    Open this publication in new window or tab >>Clotting time by free oscillation rheometry and visual inspection and a viscoelastic description of the clotting phenomenon
    2003 (English)In: Scandinavian Journal of Clinical and Laboratory Investigation, ISSN 0036-5513, E-ISSN 1502-7686, Vol. 63, no 6, p. 397-406Article in journal (Refereed) Published
    Abstract [en]

    An automated procedure for determination of clotting time in whole blood was validated by direct comparison with the reference method, visual clotting time determination. The procedure was based on a 10 Hz free oscillation rheometer (FOR) of our design, the ReoRox®4. Recalcified citrated blood samples (n=30), clotting in the range 4 to 20 min, were used in the validation. Every 30 s of the analysis, as the change in stiffness (ΔG*) of the sample was monitored by FOR, the sample cup was shortly removed from the FOR and its contents inspected for first signs of clotting, i.e. visual clotting time determination. Various FOR clotting criteria were attempted. Best correlation to visual clotting time was found when ΔG* reached 0.01 Pa, which yielded linear regression slope, intercept and r2 of 0.98, 0.09 min and 0.98, respectively. For comparison, six plasma samples were analyzed in the same way and gave almost the same results. The accuracy of the FOR determinations was checked by also analyzing, in parallel, portions of the sample with a conventional oscillation rheometer, a Bohlin VOR. The rationale is given for preferring ΔG* over G* as a FOR monitoring function in coagulation tests and for including median filtration of the primary FOR data. An extension of the FOR theory to include ΔG* and evidence in support of inhomogeneous blood clotting are also given.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-25243 (URN)10.1080/00365510310002095 (DOI)9682 (Local ID)9682 (Archive number)9682 (OAI)
    Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2017-12-13
    3. The role of platelets in blood coagulation: effects of platelet agonists and GPIIb/IIIa inhibitors studied by free oscillation rheometry
    Open this publication in new window or tab >>The role of platelets in blood coagulation: effects of platelet agonists and GPIIb/IIIa inhibitors studied by free oscillation rheometry
    2002 (English)In: Thrombosis Research, ISSN 0049-3848, E-ISSN 1879-2472, Vol. 105, no 2, p. 165-172Article in journal (Refereed) Published
    Abstract [en]

    We have studied the contribution of platelets to the coagulation of plasma and the effects of activation or inhibition of platelets on the coagulation process in unanticoagulated fresh whole blood (subsequently termed native blood). For this purpose, we have used a free oscillation rheometer (FOR), the ReoRox4, a new instrument that enables noninvasive viscoelastic measurements of clot formation in plasma and whole blood. Platelets appear essential for the initiation of coagulation if no activating surface is present. We prepared platelet-free plasma by quick centrifugation and filtration of native blood, which did not coagulate if stored in plastic containers at 37 °C but clotted if transferred to glass containers. Addition of platelet agonists, such as collagen or the thrombin receptor agonist peptide, SFLLRN, significantly accelerated the clotting of native blood and also changed the rheometer curve appearance, accelerating both onset and completion of clot formation (i.e. fibrin gel formation). Inhibition of platelet glycoprotein (GP) IIb/IIIa with the peptide-derived compound MK-852 or the antibody-derived abciximab (Reopro) prevented clot retraction and prolonged the clotting time with SFLLRN. In collagen-stimulated samples, MK-852 accelerated clotting but delayed completion of clotting while abciximab prolonged both clotting time and completion of clotting. To our knowledge, this is the first report showing that activation of platelets in native whole blood shortens the coagulation time ex vivo. It also describes a new instrument that enables studies of the viscoelastic properties of a forming whole blood clot.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-25238 (URN)10.1016/S0049-3848(02)00005-1 (DOI)9677 (Local ID)9677 (Archive number)9677 (OAI)
    Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2017-12-13
    4. Platelet phosphatidylserine exposure and procoagulant activity in clotting whole blood: different effects of collagen,TRAP and calcium ionophore A23187
    Open this publication in new window or tab >>Platelet phosphatidylserine exposure and procoagulant activity in clotting whole blood: different effects of collagen,TRAP and calcium ionophore A23187
    2003 (English)In: Thrombosis and Haemostasis, ISSN 0340-6245, Vol. 89, no 1, p. 132-141Article in journal (Refereed) Published
    Abstract [en]

    We have studied the effects of different platelet agonists onphosphatidylserine (PS) exposure and clotting times in bloodwithout anticoagulants. Similar reductions in clotting time wereobtained for collagen, TRAP-6 or calcium ionophore A23187(50 µmol/L), in spite of huge differences in PS expression[6.7 ± 2.4%, 2.3 ± 0.5% and 99.9 ± 0.1%, respectively (mean ±SD, n = 5)]. Furthermore, the clotting times were much longerfor samples with A23187 exposing the same amounts of PS assamples with collagen or TRAP-6. Annexin V reversed theclotting time reduction, but could not prevent coagulation.Addition of phospholipid vesicles containing 20% PS neitheraffected the clotting times nor induced clotting in recalcified,platelet-free plasma.We conclude that platelet PS exposure is necessary, but notsufficient, for the coagulation amplification observed whenplatelets are stimulated via physiological receptors in a wholeblood environment.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-25245 (URN)9684 (Local ID)9684 (Archive number)9684 (OAI)
    Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2017-12-13
    5. Coagulation of whole blood ex vivo: role of tissue factor, factor XI and factor XII for platelet-dependent coagulation amplification
    Open this publication in new window or tab >>Coagulation of whole blood ex vivo: role of tissue factor, factor XI and factor XII for platelet-dependent coagulation amplification
    (English)Manuscript (preprint) (Other academic)
    Abstract [en]

    Activated platelets play an important part both in the formation of the platelet plug aud as a catalytic surface for the plasma coagulation factors. We have earlier shown that activation of platelets in whole blood collected without anticoagulauts shortens the clotting time by approximately 50%. Here, we examine the involvement of TF, factor XII and factor XI in this platelet-dependent coagulation acceleration.

    Addition of an antibody against tissue factor did not prolong the clotting times for blood samples with platelet activators such as TRAP-6 or a collagen related peptide (CRP), nor for samples with only buffer added. Addition of com trypsin inhibitor (CTI) to inhibit fXIIa prolonged the clotting times by 21% for samples with eRP added. In samples with only buffer or with TRAP-6, en prolonged the clotting times by around 50%. Simultaneous addition of en and anti-TF did not cause any fnrther prolongation.

    Addition of a polyclonal antibody against factor XI caused a more marked prolongation of the clotting times, especially for TRAP-6 and buffer containing samples, but also for CRP.

    Only small amounts of thrombin-anti-thrombin (TAT) complexes were found in fresh blood samples directly after blood sampling, same amounts as described for blood down directly into tubes with anticoagulants. We cannot exclude the possibility that these small amounts could activate factor XI on the platelet surface, but that cannot explain the shortened clotting times and increased amounts of TAT found in samples with CRP added. The nature of this platelet-dependent coagulation amplification will be addressed in coming studies.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-84568 (URN)
    Available from: 2012-10-12 Created: 2012-10-12 Last updated: 2015-03-13Bibliographically approved
    6. Effects of inhibition of P2Y1 and P2Y12 on whole blood clotting, coagulum elasticity and fibrinolysis resistance studied with free oscillation rheometry
    Open this publication in new window or tab >>Effects of inhibition of P2Y1 and P2Y12 on whole blood clotting, coagulum elasticity and fibrinolysis resistance studied with free oscillation rheometry
    2003 (English)In: Thrombosis Research, ISSN 0049-3848, E-ISSN 1879-2472, Vol. 109, no 5-6, p. 315-322Article in journal (Refereed) Published
    Abstract [en]

    Introduction: In vivo, initial platelet activation is likely caused by platelet contacts with collagen in the subendothelium or from the small amounts of thrombin formed by the tissue factor/factor VIIa complex. Our aim was to study the coagulative role of ADP released by the platelets after activation with strong stimuli such as collagen and/or thrombin, and the relative importance of the platelet ADP receptors P2Y1 and P2Y12.

    Materials and methods: We used 10 Hz free oscillation rheometry to measure clotting time, clot elasticity and fibrinolysis resistance of non-anticoagulated whole blood. The platelets were activated with a collagen-related peptide (CRP), with the PAR1 thrombin receptor activating peptide TRAP-6 or by thrombin, the latter generated by small amounts of thromboplastin. To inhibit the platelet ADP receptors, we used the P2Y1 antagonist MRS2179 and the P2Y12 antagonist AR-C69931MX.

    Results: Both antagonists significantly retarded the clotting induced by CRP. The effects were most pronounced with AR-C69931MX. For TRAP-6, the same trend was seen, but the retardation was only significant with AR-C69931MX. Clotting induced by small amounts of thromboplastin was not affected by any ADP-receptor antagonist. Addition of both antagonists did not change the results as compared to samples with AR-C69931MX alone. Nor did the antagonists, one at a time or in concert, effect fibrinolysis or the elastic properties of the clot.

    Conclusion: We conclude that ADP-receptor inhibition prolongs the clotting time for whole blood activated by CRP, but that it does not affect the properties of the subsequently formed coagulum.

    National Category
    Medical and Health Sciences
    Identifiers
    urn:nbn:se:liu:diva-25244 (URN)10.1016/S0049-3848(03)00254-8 (DOI)9683 (Local ID)9683 (Archive number)9683 (OAI)
    Available from: 2009-10-07 Created: 2009-10-07 Last updated: 2017-12-13
  • 28.
    Ramström, Sofia
    et al.
    Linköping University, Department of Biomedicine and Surgery, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Lindahl, Tomas L.
    Linköping University, Department of Biomedicine and Surgery, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Coagulation of whole blood ex vivo: role of tissue factor, factor XI and factor XII for platelet-dependent coagulation amplificationManuscript (preprint) (Other academic)
    Abstract [en]

    Activated platelets play an important part both in the formation of the platelet plug aud as a catalytic surface for the plasma coagulation factors. We have earlier shown that activation of platelets in whole blood collected without anticoagulauts shortens the clotting time by approximately 50%. Here, we examine the involvement of TF, factor XII and factor XI in this platelet-dependent coagulation acceleration.

    Addition of an antibody against tissue factor did not prolong the clotting times for blood samples with platelet activators such as TRAP-6 or a collagen related peptide (CRP), nor for samples with only buffer added. Addition of com trypsin inhibitor (CTI) to inhibit fXIIa prolonged the clotting times by 21% for samples with eRP added. In samples with only buffer or with TRAP-6, en prolonged the clotting times by around 50%. Simultaneous addition of en and anti-TF did not cause any fnrther prolongation.

    Addition of a polyclonal antibody against factor XI caused a more marked prolongation of the clotting times, especially for TRAP-6 and buffer containing samples, but also for CRP.

    Only small amounts of thrombin-anti-thrombin (TAT) complexes were found in fresh blood samples directly after blood sampling, same amounts as described for blood down directly into tubes with anticoagulants. We cannot exclude the possibility that these small amounts could activate factor XI on the platelet surface, but that cannot explain the shortened clotting times and increased amounts of TAT found in samples with CRP added. The nature of this platelet-dependent coagulation amplification will be addressed in coming studies.

  • 29.
    Ramström, Sofia
    et al.
    Royal College of Surgeons in Ireland, Dublin.
    O'Neill, Sarah
    Royal College of Surgeons in Ireland.
    Dunne, Eimear
    Royal College of Surgeons in Ireland.
    Kenny, Dermot
    Royal College of Surgeons in Ireland.
    Annexin V binding to platelets is agonist, time and temperature dependent2010In: Platelets, ISSN 0953-7104, E-ISSN 1369-1635, Vol. 21, no 4, p. 289-296Article in journal (Refereed)
    Abstract [en]

    Platelets bind annexin V when stimulated with combinations of platelet agonists such as collagen and thrombin. Previous studies have demonstrated significant heterogeneity of platelets binding annexin V. The relative role of the thrombin protease-activated receptors (PARs), PAR1 and PAR4, together with different methods of platelet preparation on annexin V binding to platelets is unclear. We therefore investigated the role of PAR1- and PAR4-activating peptides in combination with collagen-related peptide on annexin V binding. In diluted whole blood, PAR1- and PAR4-activating peptides were as effective as thrombin in inducing annexin V binding. However, in washed platelets, PAR-activating peptides were less potent than thrombin at inducing annexin V binding. This difference was more pronounced when experiments were performed at 37 degrees C compared to room temperature. In studies of diluted whole blood, platelet rich plasma and washed platelets, platelets incubated at room temperature bound more annexin V than platelets incubated at 37 degrees C. We also saw a significant effect of time on annexin V binding, in that more annexin V bound to platelets with longer incubation times. In conclusion, PAR1 and PAR4-activating peptides were as effective as thrombin in inducing annexin V binding in combination with collagen-related peptide in diluted whole blood and platelet rich plasma, but not in washed platelets. In addition, incubation temperature and time has a strong influence on annexin V binding to platelets. Thus variations in these conditions may explain the differences observed between previous studies.

  • 30.
    Ramström, Sofia
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Ranby, M
    Linkoping Univ Hosp, Dept Clin Chem, S-58185 Linkoping, Sweden Linkoping Univ, Forum Scientum Grad Sch, S-58185 Linkoping, Sweden.
    Lindahl, Tomas
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    ISO-citrate is a more gentle anticoagulant than citrate1999Conference paper (Other academic)
  • 31.
    Ramström, Sofia
    et al.
    Linköping University, Department of Biomedicine and Surgery, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Rånby, Mats
    Linköping University, Department of Biomedicine and Surgery, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Lindahl, Tomas
    Linköping University, Department of Biomedicine and Surgery, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Effects of inhibition of P2Y1 and P2Y12 on whole blood clotting, coagulum elasticity and fibrinolysis resistance studied with free oscillation rheometry2003In: Thrombosis Research, ISSN 0049-3848, E-ISSN 1879-2472, Vol. 109, no 5-6, p. 315-322Article in journal (Refereed)
    Abstract [en]

    Introduction: In vivo, initial platelet activation is likely caused by platelet contacts with collagen in the subendothelium or from the small amounts of thrombin formed by the tissue factor/factor VIIa complex. Our aim was to study the coagulative role of ADP released by the platelets after activation with strong stimuli such as collagen and/or thrombin, and the relative importance of the platelet ADP receptors P2Y1 and P2Y12.

    Materials and methods: We used 10 Hz free oscillation rheometry to measure clotting time, clot elasticity and fibrinolysis resistance of non-anticoagulated whole blood. The platelets were activated with a collagen-related peptide (CRP), with the PAR1 thrombin receptor activating peptide TRAP-6 or by thrombin, the latter generated by small amounts of thromboplastin. To inhibit the platelet ADP receptors, we used the P2Y1 antagonist MRS2179 and the P2Y12 antagonist AR-C69931MX.

    Results: Both antagonists significantly retarded the clotting induced by CRP. The effects were most pronounced with AR-C69931MX. For TRAP-6, the same trend was seen, but the retardation was only significant with AR-C69931MX. Clotting induced by small amounts of thromboplastin was not affected by any ADP-receptor antagonist. Addition of both antagonists did not change the results as compared to samples with AR-C69931MX alone. Nor did the antagonists, one at a time or in concert, effect fibrinolysis or the elastic properties of the clot.

    Conclusion: We conclude that ADP-receptor inhibition prolongs the clotting time for whole blood activated by CRP, but that it does not affect the properties of the subsequently formed coagulum.

  • 32.
    Ramström, Sofia
    et al.
    Linköping University, Department of Biomedicine and Surgery, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Rånby, Mats
    Linköping University, Department of Biomedicine and Surgery, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Lindahl, Tomas
    Linköping University, Department of Biomedicine and Surgery, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Platelet phosphatidylserine exposure and procoagulant activity in clotting whole blood: different effects of collagen,TRAP and calcium ionophore A231872003In: Thrombosis and Haemostasis, ISSN 0340-6245, Vol. 89, no 1, p. 132-141Article in journal (Refereed)
    Abstract [en]

    We have studied the effects of different platelet agonists onphosphatidylserine (PS) exposure and clotting times in bloodwithout anticoagulants. Similar reductions in clotting time wereobtained for collagen, TRAP-6 or calcium ionophore A23187(50 µmol/L), in spite of huge differences in PS expression[6.7 ± 2.4%, 2.3 ± 0.5% and 99.9 ± 0.1%, respectively (mean ±SD, n = 5)]. Furthermore, the clotting times were much longerfor samples with A23187 exposing the same amounts of PS assamples with collagen or TRAP-6. Annexin V reversed theclotting time reduction, but could not prevent coagulation.Addition of phospholipid vesicles containing 20% PS neitheraffected the clotting times nor induced clotting in recalcified,platelet-free plasma.We conclude that platelet PS exposure is necessary, but notsufficient, for the coagulation amplification observed whenplatelets are stimulated via physiological receptors in a wholeblood environment.

  • 33.
    Ramström, Sofia
    et al.
    Linköping University, Department of Biomedicine and Surgery, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Rånby, Mats
    Linköping University, Department of Biomedicine and Surgery, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Lindahl, Tomas
    Linköping University, Department of Biomedicine and Surgery, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    The role of platelets in blood coagulation: effects of platelet agonists and GPIIb/IIIa inhibitors studied by free oscillation rheometry2002In: Thrombosis Research, ISSN 0049-3848, E-ISSN 1879-2472, Vol. 105, no 2, p. 165-172Article in journal (Refereed)
    Abstract [en]

    We have studied the contribution of platelets to the coagulation of plasma and the effects of activation or inhibition of platelets on the coagulation process in unanticoagulated fresh whole blood (subsequently termed native blood). For this purpose, we have used a free oscillation rheometer (FOR), the ReoRox4, a new instrument that enables noninvasive viscoelastic measurements of clot formation in plasma and whole blood. Platelets appear essential for the initiation of coagulation if no activating surface is present. We prepared platelet-free plasma by quick centrifugation and filtration of native blood, which did not coagulate if stored in plastic containers at 37 °C but clotted if transferred to glass containers. Addition of platelet agonists, such as collagen or the thrombin receptor agonist peptide, SFLLRN, significantly accelerated the clotting of native blood and also changed the rheometer curve appearance, accelerating both onset and completion of clot formation (i.e. fibrin gel formation). Inhibition of platelet glycoprotein (GP) IIb/IIIa with the peptide-derived compound MK-852 or the antibody-derived abciximab (Reopro) prevented clot retraction and prolonged the clotting time with SFLLRN. In collagen-stimulated samples, MK-852 accelerated clotting but delayed completion of clotting while abciximab prolonged both clotting time and completion of clotting. To our knowledge, this is the first report showing that activation of platelets in native whole blood shortens the coagulation time ex vivo. It also describes a new instrument that enables studies of the viscoelastic properties of a forming whole blood clot.

  • 34.
    Ramström, Sofia
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Södergren, Anna
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Tynngård, Nahreen
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Chemistry. Region Östergötland, Center for Diagnostics, Department of Clinical Immunology and Transfusion Medicine.
    Lindahl, Tomas
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Chemistry.
    Platelet Function Determined by Flow Cytometry: New Perspectives?2016In: Seminars in Thrombosis and Hemostasis, ISSN 0094-6176, E-ISSN 1098-9064, Vol. 42, no 3, p. 268-281Article in journal (Refereed)
    Abstract [en]

    Flow cytometry enables studies of several different aspects of platelet function in response to a variety of platelet agonists. This can be done using only a small volume of whole blood, and also in blood with low platelet counts. These properties, together with the increasing number of flow cytometers available in hospitals worldwide, make flow cytometry an interesting option for laboratories interested in studies of platelet function in different clinical settings. This review focuses on practical issues regarding the use of flow cytometry for platelet function testing. It provides an overview of available activation markers, platelet agonists, and experimental setup issues. The review summarizes previous experience and factors important to consider to perform high-quality platelet function testing by flow cytometry. It also discusses its current use and possibilities and challenges for future use of flow cytometry in clinical settings

  • 35.
    Ramström, Sofia
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Vretenbrant-Öberg, Karin
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Åkerström, Finn
    Leicester Medical School University of Leicester, UK.
    Enström, Camilla
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Lindahl, Tomas
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Chemistry.
    Platelet PAR1 receptor density-Correlation to platelet activation response and changes in exposure after platelet activation2008In: Thrombosis Research, ISSN 0049-3848, E-ISSN 1879-2472, Vol. 121, no 5, p. 681-688Article in journal (Refereed)
    Abstract [en]

    Introduction: A polymorphism (-14 A/T) affecting PAR1 expression on the platelet surface has recently been identified. A two-fold variation in receptor density, which correlated with the platelet response to PAR1-activating peptide (PAR1-AP), has been reported. Materials and methods: We used flow cytometry to measure the correlation between the number of PAR1 receptors and platelet activation. We also measured the changes in receptor exposure after platelet activation with PAR1-AP, ADP, PAR4-AP or a collagen-related peptide (CRP). Results: In our study, the PAR1 receptor number varied almost four-fold, from 547 to 2063 copies/platelet (mean ± S.D. 1276 ± 320, n = 70). The number of PAR1 receptors on resting platelets correlated to platelet fibrinogen binding and P-selectin expression following platelet activation with PAR1-AP (r2 = 0.30, p < 0.01 and r2 = 0.15, p < 0.05, respectively, n = 36). The correlation was not improved by exclusion of the ADP-component from the PAR1-AP-induced response. We found a trend, but no statistically significant differences in PAR1 receptor number and platelet reactivity between A/A individuals and T/A or T/T individuals. Ex vivo activation with PAR1-AP decreased PAR1 surface exposure to 71 ± 19% of the exposure on resting platelets (mean ± S.D., p < 0.01, n = 19), while activation by ADP, PAR4-AP or CRP significantly increased the exposure, to 151 ± 27%, 120 ± 21% and 138 ± 25%, respectively (n = 11, 11 and 10). Conclusions: This study shows a large variation in PAR1 receptor number in healthy individuals, a variation correlated to the platelet activation response. We found a significant reduction in PAR1 surface exposure after adding PAR1-AP, while activation with ADP, PAR4-AP or CRP increased the exposure.

  • 36.
    Rånby, Mats
    et al.
    Linköping University, Department of Biomedicine and Surgery, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Ramström, Sofia
    Linköping University, Department of Biomedicine and Surgery, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Svensson, P-O
    Linköping University, Department of Biomedicine and Surgery, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Lindahl, Tomas
    Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Clotting time by free oscillation rheometry and visual inspection and a viscoelastic description of the clotting phenomenon2003In: Scandinavian Journal of Clinical and Laboratory Investigation, ISSN 0036-5513, E-ISSN 1502-7686, Vol. 63, no 6, p. 397-406Article in journal (Refereed)
    Abstract [en]

    An automated procedure for determination of clotting time in whole blood was validated by direct comparison with the reference method, visual clotting time determination. The procedure was based on a 10 Hz free oscillation rheometer (FOR) of our design, the ReoRox®4. Recalcified citrated blood samples (n=30), clotting in the range 4 to 20 min, were used in the validation. Every 30 s of the analysis, as the change in stiffness (ΔG*) of the sample was monitored by FOR, the sample cup was shortly removed from the FOR and its contents inspected for first signs of clotting, i.e. visual clotting time determination. Various FOR clotting criteria were attempted. Best correlation to visual clotting time was found when ΔG* reached 0.01 Pa, which yielded linear regression slope, intercept and r2 of 0.98, 0.09 min and 0.98, respectively. For comparison, six plasma samples were analyzed in the same way and gave almost the same results. The accuracy of the FOR determinations was checked by also analyzing, in parallel, portions of the sample with a conventional oscillation rheometer, a Bohlin VOR. The rationale is given for preferring ΔG* over G* as a FOR monitoring function in coagulation tests and for including median filtration of the primary FOR data. An extension of the FOR theory to include ΔG* and evidence in support of inhomogeneous blood clotting are also given.

  • 37.
    Sanchez Centellas, Daniel
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Gudlur, Sushanth
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Nanyang Technology University, Singapore.
    Vicente Carrillo, Alejandro
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Sciences. Linköping University, Faculty of Medicine and Health Sciences.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Lindahl, Tomas
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Chemistry.
    A cluster of aspartic residues in the extracellular loop II of PAR 4 is important for thrombin interaction and activation of platelets2017In: Thrombosis Research, ISSN 0049-3848, E-ISSN 1879-2472, Vol. 154, p. 98-106Article in journal (Refereed)
    Abstract [en]

    Thrombin activates platelets via proteolytic cleavage of protease-activated receptors (PARs) 1 and 4. The two PARs have distinct but complementary roles. The mechanisms responsible for PAR1 activation by thrombin have been extensively studied. However, much less is known regarding thrombin activation of PAR4, especially the potential involvement of regions of PAR4 other than the N-terminal, which is bound to the catalytic site of thrombin. We have studied PAR4 in S. cerevisiae strainMMY12, an expression system in which the GPCR receptors are connected to a Lac Z reporter gene resulting in increased beta-galactosidase activity. This approach was used to assess PAR4 mutants to evaluate the contribution of different aspartic residues in facilitating PAR4 activation. Furthermore, peptides mimicking parts of the PAR4 N-terminal and the second extracellular loop (ECLII) were tested for their ability to inhibit platelet activation by thrombin. Binding of these peptides to gamma-thrombin was studied by monitoring the decrease in tryptophan fluorescence intensity of thrombin. We conclude that not only the N-terminal but also the electronegative aspartic residues D224, D230 and D235 (located in ECLII) are be important for PAR4 binding to thrombin. We further suggest that they play a role for the tethered ligand binding to the receptor, as mutations also affected activation in response to a PAR4-activating peptide mimicking the new N-terminal formed after cleavage. This agrees with previous results on PAR1 and thrombin binding. We suggest that the ECLII of PAR4 could be a potential target for antithrombotic drug development. (C) 2017 Elsevier Ltd. All rights reserved.

  • 38.
    Singh, Sukhi
    et al.
    Univ Gothenburg, Sweden.
    Damen, Tor
    Univ Gothenburg, Sweden; Sahlgrens Univ Hosp, Sweden.
    Nygren, Andreas
    Univ Gothenburg, Sweden; Sahlgrens Univ Hosp, Sweden.
    Hakimi, Caroline Shams
    Univ Gothenburg, Sweden.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Chemistry. Linköping University, Faculty of Medicine and Health Sciences. Orebro Univ, Sweden.
    Dellborgl, Mikael
    Univ Gothenburg, Sweden.
    Lindahl, Tomas
    Linköping University, Department of Clinical and Experimental Medicine, Division of Clinical Chemistry. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Chemistry.
    Hesse, Camilla
    Univ Gothenburg, Sweden; Sahlgrens Univ Hosp, Sweden.
    Jeppsson, Anders
    Univ Gothenburg, Sweden; Sahlgrens Univ Hosp, Sweden.
    Adrenaline Improves Platelet Reactivity in Ticagrelor-Treated Healthy Volunteers2019In: Thrombosis and Haemostasis, ISSN 0340-6245, Vol. 119, no 5, p. 735-743Article in journal (Refereed)
    Abstract [en]

    Background Administration of agents that enhance platelet reactivity may reduce the perioperative bleeding risk in patients treated with the adenosine diphosphate (ADP)-receptor antagonist ticagrelor. Adrenaline potentiates ADP-induced aggregation and activation in blood samples from ticagrelor-treated patients, but it has not previously been evaluated in vivo. Methods Ten healthy male subjects were included in an interventional study. A loading dose of ticagrelor (180 mg) was administered, followed 2 hours later by a gradually increased intravenous adrenaline infusion (0.01, 0.05, 0.10 and 0.15 mu g/kg/min; 15 minutes at each step). Blood pressure, heart rate, platelet aggregation (impedance aggregometry), platelet activation (flow cytometry), clot formation (rotational thromboelastometry) and adrenaline plasma concentration were determined before and after ticagrelor administration and at the end of each adrenaline step. Results Infusion of adrenaline increased ADP-induced aggregation at all doses above 0.01 mu g/kg/min. The aggregation increased from median 17 (25-75th percentiles: 14-31) to 25 (21-34) aggregation units (p = 0.012) at 0.10 mu g/kg/min. Adrenaline infusion also increased ADP-induced fibrinogen receptor activation (from 29 [22-35] to 46 [38-57%]) and P-selectin expression (from 3.7 [3.0-4.3] to 7.7 [4.7-8.6%]), both p=0.012. Adrenaline infusion reduced clot formation time (97 [89-110] to 83 [76-90] seconds, p = 0.008) and increased maximum clot firmness (59 [57-60] to 62 [61-64] mm, p = 0.007). Conclusion Infusion of adrenaline at clinically relevant doses improves in vivo platelet reactivity and clot formation in ticagrelor-treated subjects. Adrenaline could thus potentially be used to prevent perioperative bleeding complications in ticagrelor-treated patients. Studies in patients are necessary to determine the clinical importance of our observations.

  • 39.
    Singh, Sukhi
    et al.
    Department of Molecular and Clinical Medicine Institute of Medicine Sahlgrenska Academy University of Gothenburg Gothenburg Sweden.
    Malm, Carl Johan
    Department of Molecular and Clinical Medicine Institute of Medicine Sahlgrenska Academy University of Gothenburg Gothenburg, Sweden.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Chemistry. School of Medical Sciences Örebro University Örebro,Sweden.
    Hesse, Camilla
    Department of Clinical Chemistry and Transfusion Medicine Institute of Biomedicine Sahlgrenska Academy University of Gothenburg Gothenburg Sweden; Regional Blood Bank Sahlgrenska University Hospital Gothenburg, Sweden.
    Jeppsson, Anders
    Department of Molecular and Clinical Medicine Institute of Medicine Sahlgrenska Academy University of Gothenburg Gothenburg, Sweden.
    Adrenaline enhances in vitro platelet activation and aggregation in blood samples from ticagrelor-treated patients2018In: Research and practice in thrombosis and haemostasis, ISSN 2475-0379, Vol. 2, no 4, p. 718-725Article in journal (Refereed)
    Abstract [en]

    Temporarily improved platelet reactivity may reduce the bleeding in patients on antiplatelet therapy who have ongoing bleeding or who are in need of acute surgery. Adrenaline can bind to adrenergic a2A-receptors on platelets and potentially enhance platelet reactivity.

  • 40.
    Södergren, Anna
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Department of Clinical Medicine, Örebro University, Örebro, Sweden.
    Detection of Lysosomal Exocytosis in Platelets by Flow Cytometry2017In: Lysosomes: Methods and Protocols / [ed] Karin Öllinger; Hanna Appelqvist, Humana Press, 2017, Vol. 1594, p. 191-203Chapter in book (Refereed)
    Abstract [en]

    Flow cytometry is a method that allows high throughput analysis of individual cells in suspension. By inclusion of fluorescently labelled antibodies, it is possible to analyze the abundance of one or more surface antigens, such as LAMP-1, without prior lysis of cells. Here we describe the special considerations required for the investigation of lysosomal exocytosis from platelets analyzed with flow cytometry.

  • 41.
    Södergren, Anna
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Chemistry. Orebro Univ, Sweden.
    Platelet subpopulations remain despite strong dual agonist stimulation and can be characterised using a novel six-colour flow cytometry protocol2018In: Scientific Reports, ISSN 2045-2322, E-ISSN 2045-2322, Vol. 8, article id 1441Article in journal (Refereed)
    Abstract [en]

    It is recognised that platelets respond differently to activation, where a subpopulation of platelets adopt a procoagulant phenotype while others are aggregatory. However, it has not been thoroughly tested whether these subpopulations will remain in maximally activated samples, or if they are merely a result of different platelet sensitivities to agonist activation. Here platelets were activated with gradually increasing concentrations of thrombin and/or the GPVI agonist cross-linked collagen-related peptide (CRP-XL). Platelet activation was investigated using a novel six-colour flow cytometry protocol evaluating exposure of phosphatidylserine, active conformation of the fibrinogen receptor alpha(IIb)beta(3), alpha-granule and lysosomal release (P-selectin and LAMP-1 exposure), mitochondrial membrane integrity and platelet fragmentation. Upon activation by CRP-XL or thrombin+CRP-XL, platelets formed three differently sized subpopulations. Normal-sized platelets showed high exposure of aggregatory active alpha(IIb)beta(3) and intact mitochondria, while the smaller platelets and platelet fragments showed high exposure of procoagulant phosphatidylserine. The distribution of platelets between the differently sized subpopulations remained stable despite high agonist concentrations. All three were still present after 30 and 60 min of activation, showing that all platelets will not have the same characteristics even after maximal stimulation. This suggests that platelet subpopulations with distinct activation patterns exist within the total platelet population.

  • 42.
    Södergren, Anna
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Svensson Holm, Ann-Charlotte
    Linköping University, Department of Physics, Chemistry and Biology, Biology. Linköping University, Faculty of Science & Engineering.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Lindström, Eva
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences.
    Grenegård, Magnus
    Linköping University, Department of Medical and Health Sciences, Division of Drug Research. Linköping University, Faculty of Medicine and Health Sciences. University of Örebro, Sweden.
    Öllinger, Karin
    Linköping University, Department of Clinical and Experimental Medicine, Division of Cell Biology. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Pathology and Clinical Genetics.
    Thrombin-induced lysosomal exocytosis in human platelets is dependent on secondary activation by ADP and regulated by endothelial-derived substances2016In: Platelets, ISSN 0953-7104, E-ISSN 1369-1635, Vol. 27, no 1, p. 86-92Article in journal (Refereed)
    Abstract [en]

    Exocytosis of lysosomal contents from platelets has been speculated to participate in clearance of thrombi and vessel wall remodelling. The mechanisms that regulate lysosomal exocytosis in platelets are, however, still unclear. The aim of this study was to identify the pathways underlying platelet lysosomal secretion and elucidate how this process is controlled by platelet inhibitors. We found that high concentrations of thrombin induced partial lysosomal exocytosis as assessed by analysis of the activity of released N-acetyl--glucosaminidase (NAG) and by identifying the fraction of platelets exposing the lysosomal-associated membrane protein (LAMP)-1 on the cell surface by flow cytometry. Stimulation of thrombin receptors PAR1 or PAR4 with specific peptides was equally effective in inducing LAMP-1 surface expression. Notably, lysosomal exocytosis in response to thrombin was significantly reduced if the secondary activation by ADP was inhibited by the P2Y(12) antagonist cangrelor, while inhibition of thromboxane A(2) formation by treatment with acetylsalicylic acid was of minor importance in this regard. Moreover, the NO-releasing drug S-nitroso-N-acetyl penicillamine (SNAP) or the cyclic AMP-elevating eicosanoid prostaglandin I-2 (PGI(2)) significantly suppressed lysosomal exocytosis. We conclude that platelet inhibitors that mimic functional endothelium such as PGI(2) or NO efficiently counteract lysosomal exocytosis. Furthermore, we suggest that secondary release of ADP and concomitant signaling via PAR1/4- and P2Y(12) receptors is important for efficient platelet lysosomal exocytosis by thrombin.

  • 43.
    Södergren, Anna
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Tynngård, Nahreen
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Chemistry. Region Östergötland, Center for Diagnostics, Department of Clinical Immunology and Transfusion Medicine.
    Berlin, Gösta
    Linköping University, Department of Clinical and Experimental Medicine, Division of Neuro and Inflammation Science. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Immunology and Transfusion Medicine.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Responsiveness of platelets during storage studied with flow cytometry - formation of platelet subpopulations and LAMP-1 as new markers for the platelet storage lesion2016In: Vox Sanguinis, ISSN 0042-9007, E-ISSN 1423-0410, Vol. 110, no 2, p. 116-125Article in journal (Refereed)
    Abstract [en]

    Background and ObjectivesStorage lesions may prevent transfused platelets to respond to agonists and arrest bleeding. The aim of this study was to evaluate and quantify the capacity of platelet activation during storage using flow cytometry and new markers of platelet activation. Materials and MethodsActivation responses of platelets prepared by apheresis were measured on days 1, 5, 7 and 12. In addition, comparisons were made for platelet concentrates stored until swirling was affected. Lysosome-associated membrane protein-1 (LAMP-1), P-selectin and phosphatidylserine (PS) exposure were assessed by flow cytometry on platelets in different subpopulations in resting state or following stimulation with platelet agonists (cross-linked collagen-related peptide (CRP-XL), PAR1- and PAR4-activating peptides). ResultsThe ability to form subpopulations upon activation was significantly decreased already at day 5 for some agonist combinations. The agonist-induced exposure of PS and LAMP-1 also gradually decreased with time. Spontaneous exposure of P-selectin and PS increased with time, while spontaneous LAMP-1 exposure was unchanged. In addition, agonist-induced LAMP-1 expression clearly discriminated platelet concentrates with reduced swirling from those with retained swirling. This suggests that LAMP-1 could be a good marker to capture changes in activation capacity in stored platelets. ConclusionThe platelet activation potential seen as LAMP-1 exposure and fragmentation into platelet subpopulations is potential sensitive markers for the platelet storage lesion.

  • 44.
    Tynngård, Nahreen
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Transfusion Medicine . Linköping University, Faculty of Health Sciences.
    Lindahl, Tomas L
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Berlin, Gösta
    Linköping University, Department of Clinical and Experimental Medicine, Transfusion Medicine . Linköping University, Faculty of Health Sciences.
    Effects of different blood components on clot retraction analysed by measuring elasticity with a free oscillating rheometer2006In: Platelets, ISSN 0953-7104, Vol. 17, no 8, p. 545-554Article in journal (Refereed)
    Abstract [en]

    Free oscillation rheometry (FOR) using the ReoRox® 4 instrument makes it possible, at bedside, to study the coagulation process in blood over time and gives information on clotting time and coagulum elastic properties. In order to find out how various factors influence the FOR analysis we studied the coagulation process and change of elasticity over time in non-anticoagulated and citrated blood samples, plasma samples with various platelet concentrations (0-200 109/l) and blood samples with various haematocrit (0-40%). Blood samples supplemented with fibrinogen were analysed to elucidate the importance of fibrinogen on elasticity. The importance of the GPIIb/IIIa receptor on platelets was investigated by comparing the elasticity development in blood samples in presence and absence of a GPIIb/IIIa receptor inhibitor, abciximab. Anticoagulation with citrate did not have major influence on the viscoelastic properties of the coagulum. Increasing number of platelets and increasing fibrinogen concentration resulted in higher elasticity while increasing haematocrit gave lower elasticity. Blood samples with GPIIb/IIIa receptor inhibitor had very low elasticity indicating the importance of functional GPIIb/IIIa receptors. In conclusion we consider FOR to be a useful method to study the elastic properties of the coagulum. Various factors such as the number of red blood cells and platelets as well as the fibrinogen concentration should be taken into consideration when evaluating the results. The ReoRox® 4 instrument had excellent measuring range and unusually small artefactual effects on clot elasticity induced by the instrument in comparison with published results on other instruments.

  • 45.
    Tynngård, Nahreen
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Transfusion Medicine. Linköping University, Faculty of Health Sciences.
    Lindahl, Tomas L
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Räf, Tuulia
    Östergötlands Läns Landsting, Center for Diagnostics, Department of Clinical Chemistry.
    Rugarn, Olof
    Linköping University, Department of Clinical and Experimental Medicine, Obstetrics and gynecology. Linköping University, Faculty of Health Sciences.
    Berlin, Gösta
    Linköping University, Department of Clinical and Experimental Medicine, Transfusion Medicine. Linköping University, Faculty of Health Sciences.
    Free oscillation rheometry detects changes in clot properties in pregnancy and thrombocytopaenia2008In: Platelets, ISSN 0953-7104, Vol. 19, no 5, p. 373-378Article in journal (Refereed)
    Abstract [en]

    Improved methods are needed to identify patients at risk for thrombotic or bleeding events. Free oscillation rheometry (FOR) is a technique that offers information on coagulation, based on contributions of all blood components, by measurement of clotting time and changes in clot elasticity. This is the first study that evaluates FOR parameters in subjects likely to represent hypercoagulability (pregnant women) and hypocoagulability (thrombocytopenic patients). Clotting time and blood clot elasticity were measured by FOR in blood samples obtained from women in different pregnancy trimesters (n = 58), in thrombocytopenic patients before and after a platelet transfusion (n = 20) and in healthy blood donors (n = 60). The clotting time was shorter and the clot elasticity higher in pregnant women compared to the non-pregnant female blood donors. The elasticity was higher in late pregnancy compared to early pregnancy. Compared to the blood donors, the thrombocytopenic patients had lower elasticity, which was increased by a platelet transfusion, but there was no difference in clotting time. The results suggest that FOR can provide new information on the haemostatic status of patients at risk of thrombotic or bleeding events as well as information on the haemostatic effect of a platelet transfusion.

  • 46.
    Tynngård, Nahreen
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Immunology and Transfusion Medicine. Region Östergötland, Center for Diagnostics, Department of Clinical Chemistry.
    Wallstedt, Maria
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Södergren, Anna L
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Faxälv, Lars
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences. Region Östergötland, Center for Diagnostics, Department of Clinical Chemistry.
    Ramström, Sofia
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Medicine and Health Sciences.
    Platelet adhesion changes during storage studied with a novel method using flow cytometry and protein-coated beads2015In: Platelets, ISSN 0953-7104, E-ISSN 1369-1635, Vol. 26, no 2, p. 177-185Article in journal (Refereed)
    Abstract [en]

    The aim of the present study was to set up and evaluate a novel method for studies of platelet adhesion and activation in blood and platelet suspensions such as platelet concentrate (PC) samples using protein-coated polystyrene beads and flow cytometry. To demonstrate its usefulness, we studied PCs during storage. PCs were prepared by aphaeresis technique (n = 7). Metabolic variables and platelet function was measured on day 1, 5, 7 and 12 of storage. Spontaneous and TRAP-6-induced adhesion to fibrinogen- and collagen-coated beads was analyzed by flow cytometry. P-selectin and phosphatidyl serine (PS) expression was assessed on platelets bound to beads as well as on non-adherent platelets. Platelet adhesion to fibrinogen beads had increased by day 12 and adhesion to collagen beads at day 7 of storage (p < 0.05). TRAP-6 stimulation significantly increased the platelet adhesion to fibrinogen beads (p < 0.05) as well as the P-selectin and PS exposure on platelets bound to beads (p < 0.01) during the first 7 days of storage, but by day 12, significant changes were no longer induced by TRAP-6 stimulation. We demonstrate that our adhesion assay using protein-coated polystyrene beads can be used to assess the adhesion properties of platelets during storage without the addition of red blood cells. Therefore it may offer a useful tool for future studies of platelet adhesive capacity in transfusion medicine and other settings.

  • 47.
    Vretenbrant, Karin
    et al.
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of clinical chemistry.
    Ramström, Sofia
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of clinical chemistry.
    Bjerke, Maria
    Lindahl, Tomas
    Linköping University, Faculty of Health Sciences. Linköping University, Department of Biomedicine and Surgery, Division of clinical chemistry. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Chemistry.
    Platelet activation via PAR4 is involved in the initiation of thrombin generation and in clot elasticity development2007In: Thrombosis and Haemostasis, ISSN 0340-6245, Vol. 97, no 3, p. 417-424Article in journal (Refereed)
    Abstract [en]

    Thrombin is a pivotal enzyme formed in the coagulation cascade and an important and potent platelet activator. The two protease-activated thrombin receptors on human platelets are denoted PARI and PAR4. The physiological relevance of PAR4 is still unclear, as both aggregation and secretion can be accomplished by PAR1 activation alone. In the present study we have investigated the role of PARS in platelet activation, blood coagulation, clot elasticity and fibrinolysis. Flow cytometry, free oscillation rheometry and thrombin generation measurements were used to analyze blood or platelet-rich plasma from healthy individuals. Maximum PAR1 activation with the peptide SFLLRN gave fewer fibrinogen-binding platelets with lower mean fluorescent intensity than maximum PAR4 activation with AYPGKF. Inhibition of any of the receptors prolonged clotting times. However, PAR1 is more important for fibrinolysis, inhibition of this receptor prolonged all the steps in the fibrinolytic process. Clot elasticity decreased significantly when the PAR4 receptor was inhibited. In the thrombin generation measurements, PAR4 inhibition delayed the thrombin generation start and peak, but did not affect the total amount of thrombin generated. PAR1 inhibition had no significant impact on thrombin generation. We found that PAR4 is most likely activated by low concentrations of thrombin during the initial phase of thrombin generation and is of importance to the clotting time. Furthermore, we suggest that the PAR4 receptor may have a physiological role in the stabilisation of the coagulum.

  • 48.
    Vretenbrant Öberg, Karin
    et al.
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Boknäs, Niklas
    Linköping University, Department of Clinical and Experimental Medicine, Division of Microbiology and Molecular Medicine. Linköping University, Faculty of Health Sciences.
    Kalsum, Sadaf
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences.
    Ramström, Sofia
    Molecular & Cellular Therapeutics, Royal College of Surgeons in Ireland, Dublin, Ireland.
    Lindahl, Tomas
    Linköping University, Department of Clinical and Experimental Medicine, Clinical Chemistry. Linköping University, Faculty of Health Sciences. Östergötlands Läns Landsting, Centre for Laboratory Medicine, Department of Clinical Chemistry.
    Platelet thrombin receptors PAR1 and PAR4 act in a synergistic mannerManuscript (preprint) (Other academic)
    Abstract [en]

    n/a

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