CURRENT OPINION IN HEMATOLOGY

Editorial introductions
Platelets come together, in sweet harmony?!
van der Wal DE
Platelets and circulating (tumor) cells: partners in promoting metastatic cancer
Gautam D, Clarke EM, Roweth HG, Smith MR and Battinelli EM
Despite being discovered decades ago, metastasis remains a formidable challenge in cancer treatment. During the intermediate phase of metastasis, tumor cells detach from primary tumor or metastatic sites and travel through the bloodstream and lymphatic system to distant tissues. These tumor cells in the circulation are known as circulating tumor cells (CTCs), and a higher number of CTCs has been linked to poor prognoses in various cancers. The blood is an inhospitable environment for any foreign cells, including CTCs, as they face numerous challenges, such as the shear stress within blood vessels and their interactions with blood and immune cells. However, the exact mechanisms by which CTCs survive the hostile conditions of the bloodstream remain enigmatic. Platelets have been studied for their interactions with tumor cells, promoting their survival, growth, and metastasis. This review explores the latest clinical methods for enumerating CTCs, recent findings on platelet-CTC crosstalk, and current research on antiplatelet therapy as a potential strategy to inhibit metastasis, offering new therapeutic insights.
The role of germline and somatic mutations in predicting cancer-associated thrombosis: a narrative review
Lanting V, Oskam M, Wilmink H, Kamphuisen PW and van Es N
Patients with cancer have an increased risk of venous thromboembolism (VTE). Guidelines suggest to use risk assessment tools to guide decisions about thromboprophylaxis, but current tools have modest discriminatory ability. Genetic information from the germline or tumor has the potential to improve VTE prediction. Here, we provide a clinical overview of the current role of genetics in cancer-associated VTE.
Platelet transfusion
Mo A, Wood E and McQuilten Z
Platelet transfusions, used as prophylaxis or treatment for bleeding, are potentially life-saving. In many countries, demand for platelet transfusion is rising. Platelets are a limited and costly resource, and it is vital that they are used appropriately. This study will explore the evidence behind platelet transfusions in different contexts, in particular recent and important research in this area.
Platelet-derived extracellular vesicles in cardiovascular disease and treatment - from maintaining homeostasis to targeted drug delivery
Weiss L, Macleod H and Maguire PB
Cardiovascular disease (CVD) remains a major global health burden. Rising incidences necessitate improved understanding of the pathophysiological processes underlying disease progression to foster the development of novel therapeutic strategies. Besides their well recognized role in CVD, platelet-derived extracellular vesicles (PEVs) mediate inter-organ cross talk and contribute to various inflammatory diseases.
PROTACs in platelets: emerging antithrombotic strategies and future perspectives
Trory JS, Vautrinot J, May CJ and Hers I
Proteolysis-targeted chimeras (PROTACs) are heterobifunctional compounds that selectively target proteins for degradation and are an emerging therapeutic modality to treat diseases such as cancer and neurodegenerative disorders. This review will widen the area of application by highlighting the ability of PROTACs to remove proteins from the anucleate platelets and evaluate their antithrombotic potential.
Effects of selective serotonin reuptake inhibitors on platelet functions: a literature review
Mokhtarian A, Siguret V and Jourdi G
Many epidemiological studies have evidenced an increased bleeding risk associated with selective serotonin reuptake inhibitors (SSRIs), yet the underlying mechanisms remain unclear. This review summarizes data on SSRIs' effects on platelet functions assessed with assays used in clinical practice and highlights the areas that deserve further investigation.
HCT in the widening spectrum of congenital immunodeficiencies
Muratori R and Bonfim C
Hematopoietic stem cell transplantation (HSCT) and inborn errors of immunity (IEI) have been closely linked since transplantation was first used to cure severe combined immunodeficiency (SCID) in 1968. Since then, novel genes and diseases have been continually added to the ongoing list of IEI, and new data on indications and outcomes have emerged. We review recent data and progress in the field of hematopoietic cell transplantation (HCT) for IEI including new diseases and complications.
Red blood cell changes due to cancer and cancer treatments: a narrative review
Finnigan D, Hajjaj OI and Othman M
To date, there is relatively limited research investigating changes in red blood cells (RBCs), particularly qualitative changes, in cancer patients and cancer patients receiving treatment. These changes may be important in better understanding cancer-associated anemia, which is the most prevalent hematological disorder in cancer patients with wide-ranging implications on patient care and quality of life. This review aims to summarize available evidence regarding qualitative and quantitative changes in RBCs in individuals with cancer prior to treatment and in patients undergoing treatment.
Splenic filtration of red blood cells in physiology, malaria and sickle cell disease
Sissoko A, Othmene YB and Buffet P
The human spleen clears the blood from circulating microorganisms and red blood cells (RBCs) displaying alterations. This review analyzes how generic mechanisms by which the spleen senses RBC, such pitting, trapping and erythrophagocytosis, impact the pathogenesis of two major spleen-related diseases, malaria and sickle cell disease (SCD).
Tissue factor pathway inhibitor - cofactor-dependent regulation of the initiation of coagulation
Ahnström J, Petri A and Crawley JTB
In humans, tissue factor pathway inhibitor (TFPI) exists in two alternatively spliced isoforms, TFPIα and TFPIβ. TFPIα consists of three Kunitz domains (K1, K2 and K3) and a highly basic C-terminal tail. K1 inhibits the tissue factor-activated factor VII complex, K2 specifically inhibits activated factor X, K3 is essential for interaction with its cofactor, protein S, and the basic C-terminus is binds factor V-short (FV-short) with high affinity. TFPIβ consists of K1 and K2 that is glycosylphosphatidylinositol anchored directly to cell surfaces. This review explores the structure/function of TFPI and its cofactors (protein S and FV-short), and the relative contributions that different TFPI isoforms may play in haemostatic control.
Viral infection after hematopoietic stem cell transplantation
Ljungman P
Viral infections are important complications after allogeneic hematopoietic stem cell transplantation. New infections develop such as SARS-CoV-2 with the potential for severe consequences. In this review, newly published information regarding management of viral infections is discussed.
Prophylactic red cell transfusions for sickle cell disease pregnancy: increased use of therapy could transform outcomes
Alan S, Sharma D and Pecker LH
Pregnancy for people with sickle cell disease (SCD) is high risk with persistently high rates of severe maternal and fetal mortality and morbidity. Transfusion therapy is the best-studied treatment for SCD in pregnancy; hydroxyurea is not usually used because of teratogenicity concerns. In high-resource settings, red cell transfusions are likely underutilized, while in low-resource settings, they may be altogether unavailable.
Germline DDX41 mutations in myeloid neoplasms: the current clinical and molecular understanding
Kida J and Chlon TM
DDX41 mutations are the most common cause of germline predisposition to adult-onset myeloid neoplasms. The unique mutational landscape and clinical features indicate a distinct molecular pathogenesis, but the precise mechanism by which DDX41 mutations cause disease is poorly understood, owing to the multitude of DDX41 functions. In this review, we will update DDX41's known functions, present unique clinical features and treatment considerations, and summarize the current understanding of the molecular pathogenesis of the disease.
Posttransplant cyclophosphamide: a universal graft versus host disease prophylaxis
Bacigalupo A
The purpose of this review is to outline current graft versus host disease (GvHD) prophylaxis, in the era of posttransplant cyclophosphamide (PTCY), in patients with malignant and nonmalignant hematologic disorders. The original combination of PTCY with a calcineurin inhibitor (CNI) and mycophenolate (MMF), reported from the Johns Hopkins University in Baltimore, was designed for patients receiving a graft from a donor mismatched at one haplotype, so called haploidentical donor (HAPLO). In the past decade, PTCY has been widely used in HAPLO transplants worldwide, confirming the amazing efficacy of PTCY in preventing GvHD in mismatched grafts.
Unraveling lipid metabolism for acute myeloid leukemia therapy
O'Brien C and Jones CL
The aim of this review is to highlight the importance of lipids' intricate and interwoven role in mediating diverse acute myeloid leukemia (AML) processes, as well as potentially novel lipid targeting strategies. This review will focus on new studies of lipid metabolism in human leukemia, particularly highlighting work in leukemic stem cells (LSCs), where lipids were assessed directly as a metabolite.
Models to study myelodysplastic syndrome and acute myeloid leukaemia
Chao C, Martinez IG and Wagenblast E
Myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) are hematological malignancies characterized by complex genetic alterations, leading to poor clinical outcomes. Despite advances in treatment, there is an urgent need for novel therapeutic approaches. This review outlines recent progress in humanized models of MDS and AML and highlight their role in advancing our understanding of these diseases.
Unrelated hematopoietic stem cell donor registries: present reality and future prospects
Schmidt AH
Stem cell donor registries play an important role in providing stem cell products from unrelated donors to patients with severe blood diseases. In this review, important aspects of donor registry work, current challenges and possible future developments are discussed.
Control of inflammatory lung injury and repair by metabolic signaling in endothelial cells
Gould S, Herron A, Davis J, Phillips M, Chakrabarti M and Evans CE
Sepsis-induced inflammatory lung injury includes acute lung injury (ALI) and acute respiratory distress syndrome (ARDS). There are currently no effective treatments for ALI/ARDS, but clinical outcomes could be improved by inhibiting lung injury and/or promoting post-sepsis vascular repair. In this review, we describe studies of endothelial cell metabolic pathways in sepsis-induced ALI/ARDS and vascular repair and identify areas of research that deserve attention in future studies. We also describe studies of metabolic interventions that aim to inhibit ALI/ARDS and/or promote post-sepsis vascular repair, including those that target endothelial cell metabolites, endothelial cell metabolic signaling pathways, and endothelial cell metabolism.
Histon activities in the extracellular environment: regulation and prothrombotic implications
Keulen GM, Huckriede J, Wichapong K and Nicolaes GAF
Thromboembolic complications are a major contributor to global mortality. The relationship between inflammation and coagulation pathways has become an emerging research topic where the role of the innate immune response, and specifically neutrophils in "immunothrombosis" are receiving much attention. This review aims to dissect the intricate interplay between histones (from neutrophils or cellular damage) and the haemostatic pathway, and to explore mechanisms that may counteract the potentially procoagulant effects of those histones that have escaped their nuclear localization.