Glycoprotein Ibα signalling in platelet apoptosis and clearance Dianne E. van der Wal 2010 ISBN: 978-90-393-5422-3 Title: Glycoprotein Ibα signalling in platelet apoptosis and clearance Author: D.E. van der Wal Cover design and Lay-out: Visser Visuals, Amsterdam Printing: Ridderprint b.v., Ridderkerk Copyright © 2010 Dianne van der Wal, Utrecht, The Netherlands Glycoprotein Ibα signalling in platelet apoptosis and clearance Glycoproteine Ibα signallering in apoptose en klaring van bloedplaatjes (met een samenvatting in het Nederlands) Proefschrift ter verkrijging van de graad van doctor aan de Universiteit Utrecht op gezag van de rector magnificus, prof.dr. J.C. Stoof, ingevolge het besluit van het college voor promoties in het openbaar te verdedigen op vrijdag 26 november 2010 des middags te 12.45 uur door Evertdina van der Wal geboren op 12 december 1978 te Delfzijl Promotor: Prof. dr. J.W.N. Akkerman The study described in this thesis was supported by a grant from the from the Landsteiner Foundation of Blood transfusion Research (LSBR grant nr. 0510). Financial support by the Netherlands Heart Foundation and the J.E. Jurriaanse Stichting for the publication of this thesis is gratefully acknowledged. Financial support by Harry and Willy van der Wal is gratefully acknowledged. Additional financial support for the publication of this thesis by Fresenius Kabi Nederland BV, Eli Lilly Nederland BV, Boehringer Ingelheim BV, Merck Sharp & Dohme BV, Amgen BV, Greiner Bio-One is also gratefully acknowledged. Ter ere van mijn allerliefste oma For the life of a creature is in the blood (Lev 17:11) Contents Chapter 1 General introduction 13 Chapter 2 Role of glycoprotein Ibα mobility in platelet function. 51 Van der Wal DE, Verhoef S, Schutgens REG, Peters M, Wu Y, Akkerman JW. Thrombosis Haemostasis, 2010, 103: 1033-1043 Chapter 3 Platelet apoptosis by cold-induced glycoprotein Ibα clustering. 77 Van der Wal DE, Du XV, Lo KSL,Verhoef S, Rasmussen JT, Akkerman JW. Journal of Thrombosis and Haemostasis, 2010 (Epub ahead of print) Chapter 4 Arachidonate-induced platelet apoptosis. 105 Van der Wal DE, Gitz E, Du XV, Lo KSL, Versteeg S, Akkerman JW. (Submitted) Chapter 5 A patient with enhanced platelet apoptosis. 133 Van der Wal DE, Schutgens REG, Huisman A, Lo KSL, Akkerman JW. (In preparation) Chapter 6 General Discussion 157 Nederlandse samenvatting 179 Curriculum Vitae 185 Acknowledgements 188 List of Publications 195 Abbreviations 203 8 I see genius in everybody, perceive it in yourself is the difficulty (Faithless) Chapter 1 General introduction 12 Chapter 1 General Introduction Chapter 1 General Introduction 13 1.1 Platelet transfusion 1.1.1 History and clinical studies The role of platelets in haemostasis was for the first time demonstrated by Dr. William W. Duke in 1910 in a study published in JAMA. His report is now considered as an outstanding contribution to medical science. He demonstrated in a patient that the bleeding time was increased in proportion to the severity of the thrombocytopenia and showed that both bleeding time and thrombocytopenia were corrected after transfusion of fresh blood. (Figure 1 [1]). Figure 1: Transfusion of blood platelets relieves hemorrhagic disease A follow-up study with more than 400 acute leukaemia patients included over a period of 10 years (1954-1963) showed that fatal haemorrhages were reduced by 30% by regular blood transfusions compared with the period before 1954 [2]. In another study, 57 patients were examined post-mortem between 1963 and 1965 which led to the conclusion that after the introduction of platelet transfusion in 1964 about 50% less patients had died of bleeding than before [3]. Today, the transfusion of platelets is a life-saving procedure, especially for haemato- oncology patients, patients with immune thrombocytopenia and patients undergoing invasive surgery procedures. Platelet transfusions are applied as prophylaxis and for the treatment of bleeding. The threshold for platelet transfusion is a platelet count of < 10x109/L, but this number varies strongly depending on clinical criteria. 14 Chapter 1 General Introduction There is debate about the effectiveness of platelet transfusions. The question has been raised whether platelet prophylaxis in haematology patients is really effective in reducing bleeding. This question is not easy to answer. A study addressing this question would involve administration of potentially harmful and certainly costly platelet transfusions to a large number of patients, many of whom might not bleed without transfusions. Nevertheless, a few clinical trials have been performed, measuring platelet transfusion requirements, duration of the thrombocytopenia and clinical bleeding as clinical outcomes. The PLADO (Prophylactic PLAtelet DOse) [4] study was designed to determine the optimal prophylactic platelet dose. The outcome was somewhat surprising: there was no effect of the number of platelets transfused (1.1-4.4x1011 platelets per square meter of body surface area) on the incidence of bleeding. In contrast, administration of low dose platelet transfusion regimen as a prophylactically transfusion, led to significantly more transfusion episodes and a shorter interval between transfusions [4]. In the SToP study (Strategies for the Transfusion of Platelets), the effects of low (150-299x109/L) versus standard (300-600x109/L) platelet doses were compared. The StoP-study was stopped by the Data Safety Monitoring Board because of higher bleeding incidence in the group which received the low dose platelet transfusion regime [5]. The TOPPs study (Trial of Prophylactic Platelets Study) was designed to determine whether no prophylaxis is as clinically effective and safe as prophylaxis. Unfortunately, the study is not completed and conclusions cannot yet be drawn [6]. The effectiveness of the platelet transfusion is generally evaluated by determining platelet number before, 1 hour and 24 hours after the transfusion. From these follow-up values, the ‘corrected count increment’ (CCI) is calculated according to the equation: Post-transfusion – pre-transfusion platelet number CCI = -------------------------------------------------------------------------- x body surface (m2) Number of transfused platelets (x1011) A platelet transfusion is considered to be effective when the CCI ≥ 7.5 at 1 hour after transfusion and when the CCI ≥ 2.5 at 24 hours after transfusion. A low 1-hour follow-up value is seen with sepsis, serious Graft Versus Host Disease, splenomegaly and obvious haemorrhages. 1.1.2 Quality Before platelet concentrates are administered, pH, lactate production, the presence of large aggregates and “swirling” have to be determined. During the storage of platelet concentrates (PCs), pH decreases due to accumulation of lactate produced in anaerobic metabolism of glucose and free fatty acids. When the pH falls to 6.0, platelets change their shape from disc to sphere; at a pH below 6.0 shape change is irreversible [7]. The swirling phenomenon can be observed when platelets are manually resuspended and held up to a strong light and reflects the presence of discoid platelets [8]. Chapter 1 General Introduction 15 1.1.3 Platelet concentrates Today, there are three methods to prepare PCs. First, the platelet-rich plasma (PRP) method which is mainly used in the United States. Whole blood is collected in disposable plastic bags, centrifuged at slow speed to sediment red and white cells and to concentrate most platelets in the supernatant plasma. The PRP is centrifuged at a higher speed to sediment the platelets. Most plasma is removed and platelets are resuspended in a small volume of plasma or synthetic medium and stored at room temperature with mild rotation [9, 10]. Second, the buffy coat method, which is mainly used in Europe and Canada. Whole blood is centrifuged at a high speed and separated in red blood cells (RBCs), plasma and a buffy coat using an automated blood component extractor. Buffy coats are stored overnight at 22°C. Then, 4 units are pooled with 4 units of ABO-matched plasma and centrifuged. Third, the aphaeresis method is used when patients are at risk for transfusion-related infectious diseases. Blood from the donor is processed with a cell separator with an in-line centrifuge for platelet collection. Platelets are collected in citrate in plastic bags, while the other blood cells and most of the plasma are returned to the donor. Aphaeresis machines apply leukocyte reduction during the donation [9]. There is a continuing debate about the best source of PCs and the relative benefits and risks of whole blood-derived versus aphaeresis-derived PCs. The lower donor exposure associated with aphaeresis is an important advantage of this method. In contrast, whole blood-derived PCs are much cheaper than aphaeresis-derived PCs. Platelets, obtained from PRP or buffy coat method, from whole blood withdrawn from 4-8 donors, need to be pooled to PCs before transfusion to achieve the desired platelet number. For adults the standard administration dose is a total of 300-600x109 platelets or 50x109 platelets/kg body weight [8]. 1.1.4 Platelet dose Guidelines have been developed for the threshold level of the minimal platelet count in patients for transfusion of PCs: 5x109/L for patients without fever of bleeding, 10x109/L for patients with such signs and 20x109/L for patients on heparin-treatment, before bone marrow biopsy or for patients with coagulation disorders [11]. In general, increasing platelet numbers to 40-50x109/L is sufficient to stop major bleeding episodes. 1.1.5 Transfusion-related acute lung injury In about 20-30% of platelet transfusions, adverse febrile and allergic reactions occur caused by cytokine-producing leukocytes and plasma proteins [8]. Most of these reactions are mild and consist of fever, chills, rigor and allergic reactions. Febrile reactions are more likely to occur following transfusion with stored than with fresh platelets, suggesting that bioactive lipids and interleukins-1β and -6 are produced during storage. About 1 in 1500 to 1 in 10 000 transfusions of plasma containing blood products causes severe pulmonary reactions, known as transfusion related acute lung injury (TRALI).