Qualitative Platelet Disorders Research Articles

Utility of thromboelastography with platelet mapping for monitoring platelet transfusion in qualitative platelet disorders

BackgroundPatients with pathogenic variants in RASGRP2 (inherited platelet disorder (IPD)-18) exhibit normal platelet counts but impaired platelet aggregation and αIIbβ3 activation. Moderate-to-severe bleeding episodes require patients to be transfused with platelets and/or pro-hemostatic agents. We recently demonstrated that hemostatic efficacy of transfused platelets is limited by dysfunctional endogenous platelets in a mouse model of IPD-18 (Rasgrp2−/− mice), as dysfunctional platelets were recruited to the forming hemostatic plug but did not participate in clot contraction. Thus, higher amounts of transfused platelets were required to outcompete these dysfunctional cells and to reverse bleeding. ObjectiveWe here studied the usefulness of thromboelastography with platelet mapping (TEG-PM) for ex vivo monitoring of the hemostatic potential in Rasgrp2−/− mice transfused with various amounts of wild-type (WT) platelets. MethodsWhole blood (WB) samples from WT and Rasgrp2−/− mice were tested in TEG-PM and parameters for clot formation and contraction (K time, α-angle, maximum amplitude [MA]) were measured. ResultsRasgrp2−/− WB samples did not contract in TEG-PM, consistent with a critical role of this protein in αIIbβ3 activation. Addition of WT platelets improved TEG parameters in a ratio-dependent manner, consistent with our recent in vivo studies showing impaired hemostasis at a 5:1, but not at a 2:1 ratio of mutant to WT platelets. K and α values were identified as better predictors of transfusion efficacy than MA, the most platelet-dependent TEG parameter. ConclusionThis proof-of-concept study supports the use of TEG-PM to monitor platelet transfusion ratios and hemostatic potential in IPD-18 and potentially other platelet disorders.

Athn Transcends Natural History Cohort Study of Bleeding Symptoms and Treatment Outcomes in Patients with Glanzmann Thrombasthenia

Background Glanzmann thrombasthenia (GT) is a rare, inherited, qualitative platelet disorder caused by a deficiency of one or both platelet surface proteins alpha IIb beta 3. This protein on the platelet functions as the fibrinogen receptor and is essential for hemostasis. Individuals with GT have lifelong bleeding episodes that can be frequent and severe often involving the muco-cutaneous membranes. GT is an autosomal recessive disorder with variations of the ITGA2B or ITGB3 genes. The prevalence of GT is estimated to be 1:1,000,000 in the general population. In populations with high consanguinity, the prevalence is higher. Reports of the impact of living with GT are lacking. Platelets have previously been the mainstay of treatment for severe bleeding and to manage surgical bleeding in people with GT. However, platelet transfusions carry a number of risks including allergic reactions (anaphylaxis, acute lung injury), pathogen transmission, and the formation of allo-antibodies. Primary bleeding prophylaxis is currently not available and all treatment for bleeding is reactive and on-demand. As potential new therapies emerge, clinicians require unbiased, long-term data on the safety and effectiveness of both current and new therapies. Therefore, we designed a registry of people with GT with the aims of assessing the bleeding rate and phenotype for people with this condition, as well as describing their lived experience. Rationale Due to the rare nature of GT, data within individual center registries are naturally limited. There is variation in the data held and method of collection. The aim of the study is to collect biospecimens, phenotypic characteristics, bleeding patterns, and treatment utilization, from people who have been diagnosed with GT. To achieve this, a comprehensive, multi-institutional, observational cohort study will be conducted to: Allow collection of longitudinal safety and clinical practice data for treatments in patients with GT, allowing monitoring of recently approved and well-established therapies; Aid new discovery, through the collection of biospecimens and phenotype data; Provide sufficient, unified data capture in participants with this rare disorder across the United States. Objectives To describe the bleeding phenotype in GT, including the frequency of bleeds, the Site of bleeds, and to describe real-world effectiveness of therapies used in GT, by evaluating; the frequency of bleeds, Patient reported outcomes, Healthcare and treatment utilization, To create a database for future research. Methods ATHN Transcends (NCT04398628) assesses the safety and effectiveness of contemporary therapies for people with inherited bleeding and clotting disorders. The primary aim of ATHN Transcends is to collect specific adverse events harmonized with the European Haemophilia Safety Surveillance (EUHASS). The study is constructed to allow the addition of specific modules. We have designed the GT module in ATHN Transcends to assess the safety and effectiveness of current therapy for GT. In addition, we will be collecting data around the actual bleeding rate in those who live with GT as well as more fully describing the lived experience of being impacted by GT. The study will be conducted through ATHN-affiliated centers who care for those impacted by GT. Study Design This study is a longitudinal, natural history, observational cohort study of approximately 50 participants with GT at 16 ATHN-affiliated treatment centers across the United States and a sub-cohort from one international ATHN Affiliate. The minimum planned duration of study participation for participants is approximately 18 months. Up to 10 pediatric subjects aged 2 years to <10 years, up to 10 aged 10 to <18 years, and a minimum of 30 adults >18 years with GT are expected to be enrolled. Each subject will complete a daily record for three months of bleeding event details, and any treatments. Summary ATHN Transcends has received central IRB approval and is currently being rolled out across participating American Thrombosis and Hemostasis Network (ATHN) Affiliates in the United States. Enrollment in the GT Module can begin as soon as a site opens ATHN Transcends to enrollment. Conclusion ATHN Transcends provides a real-world mechanism in which to collect safety and effectiveness data of contemporary therapies for people with GT. The GT Module of ATHN Transcends will allow collection of Good Clinical Practice-grade data.

Multimodality Platelet Evaluation By Mass Cytometry and Genetic Analysis in Patients with Bleeding Disorders

Introduction: Bleeding disorders are a diverse group of conditions characterized by abnormal bleeding tendencies. Platelet dysfunction is a common underlying cause and although traditional platelet aggregometry is important in the clinical work-up, platelet functional assays often provide limited diagnostic insights, prompting the need for more advanced techniques and approaches. This study aims to explore the utility of mass cytometry combined with genetic analysis in assessing platelet function in patients with otherwise unspecified bleeding tendencies. Methods: In a single-center prospective study, enrolled patients with clinical and laboratory suspicion of platelet-related bleeding disorders were subjected to multimodality evaluation. Mass cytometry (CyTOF) allows for simultaneous evaluation of multiple platelet markers on single cells, including those involved in platelet activation, aggregation, and adhesion, through a panel of heavy metal-conjugated antibodies. Whole genome sequencing with targeted analysis was utilized to identify potential genetic variants associated with quantitative and qualitative platelet disorders and correlated with CyTOF findings. Results: CyTOF revealed altered platelet markers associated with activation, aggregation, and adhesion in 40% (n=14) of total participants (n=35) with suspected platelet-related bleeding disorders ( Table 1). CyTOF showed significant concordance with platelet aggregometry in 74% of participants (data not shown). Alterations in specific CyTOF markers (e.g., PAC-1, CD40L) correlated with bleeding risk by univariate analysis of patients stratified to high vs low risk groups based on ISTH bleeding assessment tool (ISTH-BAT) ( Table 1). Multivariate analysis using a random forest machine learning algorithm identified variables most predictive of bleeding risk, including CD40L, PAC-1, P-selectin, and mean platelet volume. Genetic analysis identified one or more variants in genes implicated in qualitative and quantitative platelet disorders in 61% (n=19) of total patients analyzed ( Figure 1). Abnormal CyTOF findings were associated with greater proportion of variants detected (79% with abnormal CyTOF vs 53% with normal CyTOF) ( Figure 1). Direct associations between specific mass cytometry findings and genetic variants (i.e., GPIIb, GPIIIa, GPIb, GPIX, etc.) were discovered for several patients, providing important information in evaluating variant pathogenicity and diagnostic validation. Conclusion: This study highlights the potential of integrating mass cytometry and genetic analysis to assist in the diagnosis of otherwise unspecified bleeding tendencies, bleeding risk stratification, and patient management. Our findings enhance the understanding of platelet function in patients with bleeding disorders and provide valuable insights into the complex relationship between platelet phenotypes and genetic determinants. Further investigations with a larger patient cohort are warranted to validate and expand upon these initial correlations and explore their clinical implications in diagnosis and management of bleeding disorders.

Role of MicroRNA-326 and its Target Genes Bcl-xL and Bak as Potential Markers in Platelet Storage Lesion in Blood Banks

Platelet transfusion is crucial in the management of various conditions such as quantitative and qualitative platelet disorders. A serious problem that impacts public health is the shortage of Platelet concentrates (PCs) that frequently affect few blood donors’ countries, such as Egypt. This has necessitated the need to establish novel standards for determining the quality of PC during storage. It was found that microRNAs (miRNA) differential expression profile is a helpful tool for recognition of physiological platelet changes during storage. The aim of the current study was to highlight the role of platelet miRNA-326 and its putative target apoptotic genes, Bcl-xL and Bak, and their role in platelet storage lesion (PSL). Differential expression of miRNA-326 and its target genes in the apoptotic pathway, Bcl-xL and Bak was done using quantitative real time PCR (QR-PCR) on different storage points at day 0, day 3 and day 5 in blood bank. The results of the current study revealed over expression of miRNA-326 throughout days of storage resulted in down regulation of Bcl-xL gene and subsequently up regulation of Bak gene. MiRNA-326 contributes to platelet apoptosis and PSL through inhibition of anti-apoptotic Bcl-xL expression and enhancing pro-apoptotic Bak expression. Differential miRNA-326 and its target gene, Bcl-xL and Bak, expression levels at different points of platelets storage are promising tools as biomarkers for platelets undergoing PSL in blood banks.

Iron deficiency anemia and bleeding management in pediatric patients with Bernard-Soulier syndrome and Glanzmann Thrombasthenia: A single-institution analysis.

Frequent and severe bleeding events (SBE) in patients with inherited qualitative platelet disorders Bernard-Soulier Syndrome (BSS) and Glanzmann Thrombasthenia (GT) can lead to secondary iron deficiency anemia (IDA). SBE are primarily treated with platelet transfusions or recombinant activated factor VII (rFVIIa) infusions. The impact of IDA on bleeding management and disease outcomes is understudied. To evaluate bleeding management, outcomes, and any association with IDA in pediatric patients with BSS and GT. Retrospective chart-review of pediatric patients with BSS or GT followed at a single hemophilia treatment center between 2007 and 2019. We identified 14 patients with BSS (n = 2) or GT (n = 12). Patients received rFVIIa (7%), platelet transfusions (7%), or a combination of both (57%) for SBE. Eleven patients (79%) had IDA requiring oral and/or intravenous iron replacement and 50% required red blood cell transfusions. Due to recurrent SBE and refractory IDA, three patients (21%) received rFVIIa prophylaxis at 90μg/kilogram 2-3times/week for ≥15months. Patients initiated on rFVIIa prophylaxis had a median baseline hemoglobin of 9.8 g/dL (min-max: 8.0-10.7 g/dL) compared to 11.7 g/dL (8.4-13.8 g/dL) for patients treated on-demand. Following initiation of rFVIIa prophylaxis, median hemoglobin and ferritin increased by 1.3 g/dL (0.7-2.5 g/dL) and 14.6 ng/mL (0.2-42.9ng/mL), respectively, and bleeding rates were reduced by 7-78%. IDA is a known complication of recurrent bleeding events in individuals with inherited bleeding disorders. Routine monitoring for IDA may help improve bleeding management and reduce bleed burden in BSS/GT.

Thromboxane A2 Deficit Diagnosis in a Patient with Suspicion of Von Willebrand Disease

Thromboxane A2 receptor deficiency is a qualitative platelet disorder that partially impedes adequate platelet signaling and aggregation. Generally, these patients have mild hemorrhagic manifestations in basal conditions, but may show severe bleeding when faced with a hemostatic challenge. We present the case of a 30-year-old female patient that arrives at the Hematology service with an undiagnosed bleeding disorder. She presented hemorrhagic complications during an augmentation mammoplasty and during an exodontia procedure, yet, during a C-section she presented none. At the first consultation she had normal coagulation factor levels by coagulometry, and normal platelet aggregation test for ADP, ristocetin, collagen and epinephrine. A platelet aggregation test for arachidonic acid confirmed thromboxane A2 deficit disorder. Thromboxane A2 deficit disorder is a rare qualitative platelet disorder that requires an extensive knowledge of coagulation and platelet function and tests, and a high level of clinical suspicion. These tests are especially difficult to interpret during pregnancy due to normal modifications to bodily function during this process.

Outcomes after Intrauterine Device Insertion for Heavy Menstrual Bleeding in Young Women with and without Inherited Bleeding Disorders

Introduction: Data on hormonal intrauterine device (IUD) related adverse events in young women with inherited bleeding disorders (IBDs) are limited. Our primary objectives were to 1) examine adverse outcomes following IUD insertion in adolescents with heavy menstrual bleeding (HMB) and 2) compare IUD event-free survival in patients with and without IBDs. Methods: We performed a multi-center retrospective study of adolescents presenting to Young Women's Hematology Clinics at Nationwide Children's Hospital and Children's Medical Center, Dallas. All new patients with HMB at both clinics were enrolled in a HMB registry. We included registry participants who presented for evaluation of HMB between February 2014-February 2020 and had a levonorgestrel IUD placed. Electronic medical records were reviewed for clinical history, patient demographics, IBD diagnosis, IUD insertion, and post-IUD insertion follow up. We determined a priori IUD expulsion, removal due to malposition, or removal due to excessive pain or bleeding as clinically relevant adverse outcomes. Results: We identified 78 patients with IUD placement, of which 43 patients were diagnosed with IBDs. Of patients with IBD, the most common diagnoses were von Willebrand's disease/low von Willebrand factor (n=15), joint hypermobility syndrome/Ehlers-Danlos (n=15), and qualitative platelet disorder (n=9). The majority of patients were white (78%); 15% identified as Black. Nine percent of patients were Hispanic. Ninety percent of patients had failed at least one other method prior to IUD placement with the most common being combined estrogen/progestin oral contraceptive pills (79%), followed by progestin-only pills (37%), non-hormonal medications (DDAVP or anti-fibrinolytics) (26%), and depot medroxyprogesterone acetate (22%). Approximately half of the patients had an IUD inserted under general anesthesia (58%), with the remainder undergoing insertion in an outpatient clinic setting. Patients with IBDs were younger at time of IUD insertion (mean age 14 years, range 11-18) as compared to those without bleeding disorders (mean age 15 years, range 12-19, p=0.048). One-third (32%) of patients were sexually active prior to IUD insertion; this was not significantly different between groups. IUDs were found to be malpositioned or expelled on recheck in 21% of patients with IBD and 19% of patients without IBD (p=.87). Following IUD insertion, there was no significant difference in breakthrough bleeding that required treatment between the two groups, which occurred in 42% of patients with IBD and 26% in patients without IBD (p=.18). Patients with IBD were less likely than patients without IBD to request their IUD be removed prematurely (2% vs 20%, p<0.05). Overall, we found an annual rate of 0.25 adverse IUD events per 1 year of IUD insertion, with all adverse events occurring in the first 20 months after placement. Conclusions and future directions: While rates of expulsion and malposition were not higher in adolescents with IBD when compared to those without, they were higher than that of the general population (20% in our adolescent population with HMB vs 10% in the general population of nulliparous women <20 years of age, Madden et al, Obstetrics & Gynecology, 2015). Our study suggests that breakthrough menstrual bleeding after IUD insertion is equally likely in teens with HMB regardless of the diagnosis of IBD, with over a third of all patients requiring adjunctive therapy for breakthrough bleeding after IUD insertion. These findings highlight the need for appropriate counseling in this unique population as hormonal IUDs constitute an important treatment option for HMB in adolescents with and without IBD. Our work can inform shared decision making and patient counseling for the use of IUDs in young women with HMB and emphasizes the need for close follow-up after insertion to monitor for break through bleeding or malposition. Further research is needed to prospectively measure clinical outcomes and patient-reported outcomes after IUD insertion in young women with IBDs. Disclosures O'Brien: Bristol Myers Squibb: Consultancy, Membership on an entity's Board of Directors or advisory committees.

Platelet transfusion for patients with platelet dysfunction: effectiveness, mechanisms, and unanswered questions.

In this review, we discuss current clinical guidelines and potential underlying mechanisms regarding platelet transfusion therapy in patients at risk of bleeding, comparing management of patients with thrombocytopenia versus those with qualitative platelet disorders. Platelet transfusion therapy is highly effective in managing bleeding in patients with hypoproliferative thrombocytopenia. Clinical trials have demonstrated that platelet transfusion can be used at a lower trigger threshold and reduced platelet doses, and may be used therapeutically rather than prophylactically in some situations, although additional data are needed. In patients with inherited platelet disorders such as Glanzmann's Thrombasthenia or those with RASGRP2 mutations, platelet transfusion may be ineffective because of competition between transfused and endogenous platelets at the site of vascular injury. Successful management of these patients may require transfusion of additional platelet units, or mechanism-driven combination therapy with other pro-hemostatic agents. In patients on antiplatelet therapy, timing of transfusion and inhibitor mechanism-of-action are key in determining therapeutic success. Expanding our understanding of the mechanisms by which transfused platelets exert their pro-hemostatic function in various bleeding disorders will improve the appropriate use of platelet transfusion.

Characterizing female patients with haemophilia A: Administrative claims analysis and medical chart review.

Haemophilia A (HA) is a male-predominant disorder, yet women and girls can have factor VIII (FVIII) deficiency with bleeding events requiring treatment. This study aimed to identify and characterize female patients with HA. Administrative claims dated 01 January 2012-31 July 2016 were accessed for patients with 18months' coverage by commercial or Medicare Advantage with Part D insurance. Patients were included by HA diagnoses or treatments and/or bleeding-related diagnoses or procedures, and excluded by haemophilia B or qualitative platelet disorder diagnoses. A sample of charts was examined for bleeding history, HA therapies and bleeding treatments. All-cause healthcare utilization and costs were also described. Among 353 patients meeting initial inclusion criteria, 86 charts were procured, with 8 patients identified as having HA. Their mean age was 60±17years and most were Medicare-insured. The mean Charlson Comorbidity Index score was 2.50±2.56; the most prevalent comorbid conditions involved coagulation/haemorrhage, fluid/electrolyte balance and non-traumatic joint disorders. Over 18months, a mean of 54 ambulatory visits and 120 pharmacy fills were observed; mean medical costs were $86694 and pharmacy costs were $25396. Identifying females with HA is challenging using healthcare claims, because diagnostic nomenclature is unclear for female patients treated for bleeding events. Although chart abstraction enhanced claims data, very few female patients were identified with HA. Nevertheless, even in a small sample, sizeable burden in comorbidity and healthcare use was observed. Improved nomenclature and coding for HA diagnoses for women and girls is key to improving research and treatment.

Successful Management of Endometriosis, In Vitro Fertilization, Pregnancy, and Postpartum Recovery in a Woman with Glanzmann's Thrombasthenia

Abstract Background: Glanzmann's thrombasthenia (GT) is an autosomal, qualitative platelet disorder that is genetically recessive. This report is about a patient with GT, complicated by infertility...

Sticky Platelet Syndrome: 35 Years of Growing Evidence.

Since the identification of antithrombin deficiency by Egeberg in 1956, ongoing research in prothrombotic defects continues to progress. Interestingly, past research has predominantly focused on coagulation factors and not on other components of the hemostatic system. The possible role of platelet function defects in the development of thrombotic events was suggested for the first time in the late 1970s, when an increased platelet adhesiveness and aggregation after epinephrine (EPI) and adenosine diphosphate (ADP) was found in a group of patients with unexplained transient ischemic attack. Clinical evidence for other types of thrombotic events (e. g. myocardial infarction, ischemic stroke, optic neuropathy, and pregnancy-related complications) with similar laboratory findings was provided by several authors in the 1980s and 1990s, with Drs. Mammen and Bick undertaking key research. The familial occurrence was noted as well, and the term sticky platelet syndrome was introduced by Holliday in 1983 to describe the defect. The term in our present understanding describes a thrombophilic qualitative platelet disorder characterized by increased in vitro platelet aggregation after the addition of very low concentrations of ADP and/or EPI and an increased risk of thromboembolic (predominantly arterial) events. Although now recognized for 35 years, significant issues, namely its etiology, inheritance, epidemiology, and diagnostics, remain a matter of vigorous debate. The aim of this review is to summarize the history, key works, and present understanding of the syndrome and to outline present-day diagnostic and clinical problems and controversies.

Trombosis venosa subclavia asociada a electrodo de marcapasos y síndrome de la plaqueta pegajosa

Sticky platelet syndrome is a qualitative platelet disorder in which low concentrations of adrenaline and adenosine diphosphate produce considerable platelet hyperaggregability. There has been much speculation on the origin of this disorder as its pathophysiological mechanisms of action are not yet clear. From a clinical point of view, it is associated with recurrent arterial and venous thrombosis in young patients, miscarriages, other obstetric complications and recurrent headaches.Its familial presentation has been described in the literature, suspecting that it is of a dominant autosomal hereditary nature. An acquired phenotype of the disease has also been reported in some particular patients, such as patients with chronic kidney disease on renal replacement therapy or after a kidney transplant, as well as in patients with inflammatory processes or immunosuppression. The case is presented of a patient with a history of difficult to manage headaches, a hypertensive syndrome associated with the pregnancy, and a foetal death. She also had sick sinus node syndrome and dysautonomia managed with a definitive dual-chamber pacemaker with a CLS sensor. There was then a thrombosis in the subclavian vein associated with the pacemaker electrode, being recurrent despite anticoagulation with warfarin and rivaroxaban, and even despite anti-aggregation treatment with acetyl salicylic acid. She was subsequently diagnosed with sticky platelet syndrome.

Pilot study of novel lab methodology and testing of platelet function in adolescent women with heavy menstrual bleeding.

IntroductionApproximately 40% of adolescent women experience heavy menstrual bleeding (HMB), and 10–62% of them have an underlying bleeding disorder (BD). Diagnosing BD remains challenging due to limitations of available clinical platelet function assays.AimTo characterize platelet function in a population of adolescent women with HMB using small-volume whole blood assays.MethodsAnticoagulated whole blood was used to assess platelet GPIIbIIIa activation, α-granule secretion, and aggregation in response to multiple agonists. Platelet adhesion on collagen or von Willebrand Factor (VWF) under static and shear flow was also assessed.ResultsFifteen participants with HMB were included in the study, of which eight were diagnosed with a clinically-identifiable BD. Platelet activation was blunted in response to calcium ionophore in participants without a BD diagnosis compared to all other participants. Impaired GPIIbIIIa activation was observed in response to all GPCR agonists, except ADP, in participants with qualitative platelet disorders. Our assays detected platelet aggregation in the majority of participants with a BD in response to ADP, CRP, TRAP-6, or U46619. Platelet adhesion and aggregation on collagen and VWF was decreased for participants with VWD.ConclusionParticipants with and without BD exhibited aberrant platelet function in several assays in response to select agonists.

Recognition and management of platelet-refractory bleeding in patients with Glanzmann's thrombasthenia and other severe platelet function disorders.

Patients with rare qualitative platelet disorders or platelet function disorders (PFDs) may present to the hospital physician with severe bleeding episodes or excessive surgical bleeding. Although standard treatment consists of platelet transfusions, repeated transfusions may result in the development of antiplatelet antibodies (APA) or clinical refractoriness, rendering further platelet therapy ineffective. In such settings, an approved treatment option for patients with Glanzmann’s thrombasthenia (GT), one of the well-known rare PFDs, is recombinant activated coagulation factor VII (rFVIIa). Data regarding the efficacy of rFVIIa in patients with GT and platelet refractoriness are available from a large patient registry, an international survey, and multiple case reports and demonstrate efficacy in patients with and without refractoriness or APA. This article reviews the rFVIIa clinical data in patients with GT and platelet refractoriness and discusses clinical implications relevant to the hospital-based physician. Because uncontrolled bleeding can be life-threatening, hospital physicians should be alert to the signs of platelet refractoriness, be able to recognize continued internal or external bleeding, and know how to adapt treatment regimens for the effective management of bleeding. The management of patients who receive rFVIIa should occur in consultation with a hematologist with experience in PFDs, and patients with suspected platelet refractoriness should be referred to such a hematologist as early as possible. A critical unmet need is the development of a definition of an adequate response to platelet transfusion, which would facilitate early recognition of platelet refractoriness in patients with PFDs who exhibit a normal platelet count.

Cardiovascular and Hemostatic Disorders: SOCE and Ca2+ Handling in Platelet Dysfunction.

Among the Ca2+ entry mechanisms in platelets, store-operated Ca2+ entry (SOCE) plays a prominent role as it is necessary to achieve full activation of platelet functions and replenish intracellular Ca2+ stores. In platelets, as in other non-excitable cells, SOCE has been reported to involve the activation of plasma membrane channels by the ER Ca2+ sensor STIM1. Despite electrophysiological studies are not possible in human platelets, indirect analyses have revealed that the Ca2+-permeable channels involve Orai1 and, most likely, TRPC1 subunits. A relevant role for the latter has not been found in mouse platelets. There is a body of evidence revealing a number of abnormalities in SOCE or in its molecular regulators that result in qualitative platelet disorders and, as a consequence, altered platelet responsiveness upon stimulation with multiple physiological agonists. Platelet SOCE abnormalities include STIM1 and Orai1 mutations. This chapter summarizes the current knowledge in this field, as well as the disorders associated to platelet SOCE dysfunction.

Improving Our Ability to Treat Patients with Qualitative and Quantitative Platelet Disorders

Improving Our Ability to Treat Patients with Qualitative and Quantitative Platelet Disorders

Inherited Platelet Function Disorders (IPFDs).

Inherited platelet function disorders (IPFDs) are a wide spectrum of qualitative platelet disorders with variable bleeding tendency, ranging from mild bleeding to severe life-threatening episodes. Diagnosis and classification of IPFDs is a challenge worldwide. The present study aims to present a proper classification, describe the molecular basis and clinical presentations as well as some diagnostic clues for these disorders. All relevant publications were searched using appropriate keywords. IPFDs can be divided into four major groups including defects of platelet surface glycoproteins, platelet granules and secretion disorders, platelet signaling defects, and transcription-related platelet disorders. Some of these disorders, such as Glanzman thrombasthenia, are more common, with severe bleeding, while most of these disorders are extremely rare with mild bleeding. A proper classification, accompanied by familiarity with diagnostic clinical and laboratory features of IPFDs, can be helpful in in-time and exact diagnosis of these complicated bleeding disorders.

Identification of Qualitative Platelet Disorders in Adolescent Women with Heavy Menstrual Bleeding

Introduction: Nearly 40% of adolescent women experience heavy menstrual bleeding (HMB), and identifiable bleeding disorders are diagnosed in only 20-60% of these patients. We suspect that qualitative platelet disorders contribute to HMB, but are under-diagnosed. A pilot study was conducted to evaluate platelet function in adolescent women with HMB employing four novel, small-volume, whole blood platelet function assays. In addition, primary and secondary hemostasis, bleeding phenotype, and quality of life were assessed.Methods: Patients referred to the Young Women’s Hematology Clinic at Oregon Health & Science University for evaluation of HMB were offered participation in the study. Participants underwent standard review of their medical and family history and physical exam. Standard lab evaluation included CBC, PT, PTT, fibrinogen, thrombin time, Von Willebrand Panel, PFA-100, and iron studies with platelet aggregation or phenotyping performed if clinically indicated. Using less than 0.5 mL of whole blood, platelet function was assessed with four novel platelet function assays: assessment of platelet activation, secretion, and aggregation was assessed by flow cytometry analysis, while platelet adhesion and aggregation was assessed under shear in a capillary tube. Quality of life (QOL) was assessed using the PedsQL tool. Bleeding phenotype was assessed with the ISTH Bleeding Assessment Tool (ISTH BAT). Menorrhagia was assessed with the Pictorial Bleeding Assessment Chart (PBAC), the Philipp Tool and the clinical history.Results: Nine participants have enrolled on study to date, with 2 completing the 3-month visit. The median age of the cohort was 16 years (14-18 years). Eight out of nine categorized their period as heavy, 6 also had epistaxis, and 7 reported excessive bruising. The median ISTH BAT score was 4 (3-7). Of the 7 patients who had a Philipp Score obtained, 5 were positive. Median PBAC score was 161 (64-196). Median ferritin was 13 ng/mL (4-65 ng/mL). Median QOL psychosocial score was 70 (68.36-88.25), comparable to that of pediatric patients with cancer. Of the 9 participants, 6 had platelet aggregation and phenotyping. Four participants did not receive a bleeding disorder diagnosis, 1 was diagnosed with Type 1 VWD, 1 was diagnosed with bleeding disorder, NOS, and 1 was diagnosed with Ehlers Danlos Syndrome. Two participants were diagnosed with a qualitative platelet disorder (QPD): one based on platelet aggregation and one based on thromboelastography. The four novel platelet function assays confirmed platelet function abnormalities in the participants diagnosed with QPD’s (Figure 1&2). Impaired platelet response to agonist stimulation was also observed in participants with non-platelet disorder bleeding disorder diagnoses and in participants without a bleeding disorder diagnosis.Conclusions: In this pilot study, the etiology of HMB in adolescent women was evaluated with four novel platelet assays in addition to standard assays of hemostasis. A bleeding disorder diagnosis was not made with standard evaluations in 4 out of 9 participants. The novel assays detected platelet abnormalities not observed using currently available clinical labs, and confirmed the presence of abnormal platelet function in participants with abnormal platelet function testing. These assays require significantly less blood volume than currently available assays and expand investigation of platelet function to platelet adhesion and platelet interactions in whole and flowing blood. Further work is needed to determine the sensitivity and specificity of the novel assays in detecting platelet dysfunction. Continued investigation into the impact of HMB on the adolescent female population is needed. [Display omitted] [Display omitted] DisclosuresHaley:CSL Behring: Honoraria; Baxalta: Membership on an entity's Board of Directors or advisory committees. Recht:Biogen: Membership on an entity's Board of Directors or advisory committees; CSL Behring: Membership on an entity's Board of Directors or advisory committees; Biogen: Research Funding; Genentech: Research Funding; Novo Nordisk: Research Funding; Baxalta: Research Funding; Novo Nordisk: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees.

Rapid Evaluation of Platelet Function With T2 Magnetic Resonance.

Objectives: The clinical diagnosis of qualitative platelet disorders (QPDs) based on light transmission aggregometry (LTA) requires significant blood volume, time, and expertise, all of which can be barriers to utilization in some populations and settings. Our objective was to develop a more rapid assay of platelet function by measuring platelet-mediated clot contraction in small volumes (35 µL) of whole blood using T2 magnetic resonance (T2MR).Methods: We established normal ranges for platelet-mediated clot contraction using T2MR, used these ranges to study patients with known platelet dysfunction, and then evaluated agreement between T2MR and LTA with arachidonic acid, adenosine diphosphate, epinephrine, and thrombin receptor activator peptide.Results: Blood from 21 healthy donors was studied. T2MR showed 100% agreement with LTA with each of the four agonists and their cognate inhibitors tested. T2MR successfully detected abnormalities in each of seven patients with known QPDs, with the exception of one patient with a novel mutation leading to Hermansky-Pudlak syndrome. T2MR appeared to detect platelet function at similar or lower platelet counts than LTA.Conclusions: T2MR may provide a clinically useful approach to diagnose QPDs using small volumes of whole blood, while also providing new insight into platelet biology not evident using plasma-based platelet aggregation tests.

Platelet concentrates: Balancing between efficacy and safety?

Platelet transfusions continue to be the mainstay to treat patients with quantitative and qualitative platelet disorders. Each year, about 10millions of platelet transfusions are administered to patients worldwide with marked differences in usage between regions depending on socioeconomic development of the countries. Unfortunately, its use is associated to immune and non-immune side effects. Among the non-immune, bacterial contamination is still the major infectious risk. When bacterial culture methods are introduced for preventing bacterial septic reactions it has been found that this strategy reduce to one half the septic reactions, but do not eliminate completely that risk. To remove completely the risk, a new bacteria detection test at the time of issuance in the case of platelets stored for four or five days would be needed. Pathogen inactivation (PI) methods already in the market (based in the addition of amotosalen (A-L) or riboflavin (R-L) and the illumination with ultraviolet light) or under development (ultraviolet light C and agitation) have shown to be efficacious in the inactivation of bacteria and no cases of septic reactions associated to a pathogen-reduced product has been identified. However, it has been shown that PI technologies have measurable effects on platelet in vitro parameters and reduce the recovery and survival of treated platelets in vivo. Although these effects do not hamper the hemostatic capacity of treated platelets, an increased usage associated with PI technologies has been reported. This increase in utilization seems to be the toll to be paid if we want to completely eliminate the risk of bacterial sepsis in the recipients of platelet transfusion.