P-selectin glycoprotein ligand-1 positive microparticles in allogeneic stem cell transplantation of hematologic malignancies

An update on recent studies of extracellular vesicles and their role in hypercoagulability in thalassemia (Review)

Thromboembolic events are a significant clinical concern in thalassemia and hemoglobinopathies, highlighting the need for new strategies to treat and detect these specific hematologic complications. In recent years, extracellular vesicles (EVs) have garnered interest due to their role in cell-to-cell communication, including angiogenesis, immune responses and coagulation activation. Their multifaceted role depends on the cellular origin and cargo, making them potential diagnostic biomarkers and therapeutic agents. The present review highlights recent advances in understanding the involvement of EVs in hypercoagulability in thalassemia, the characterization of circulating EVs and the potential for using EVs as predictive biomarkers. β-Thalassemia intermedia exhibits a high incidence of thromboembolic events, contributing to significant morbidity and mortality. Advanced technologies have enabled the profiling and characterization of circulating EVs in patients with β-thalassemia through various techniques, including flow cytometry, proteomic studies, reverse transcription-quantitative PCR, transmission electron microscopy, nanoparticle tracking analysis and western blot analysis. Microparticles from splenectomized β-thalassemia/hemoglobin E patients induce platelet activation and aggregation, potentially contributing to thrombus formation. The abundance of these microparticles, primarily released from platelets and damaged red cells, may have a role in thromboembolic events and other clinical complications in thalassemia. This suggests a promising future for EVs as diagnostic and predictive biomarkers in thalassemia management.

Circulating extracellular vesicles as a predictive biomarker for acute graft-versus-host disease

The diagnosis and management of graft-versus-host disease (GVHD) have remained important challenges in allogeneic stem cell transplantation (allo-SCT). Novel diagnostic methods and therapeutic interventions are needed to further improve on patient outcomes. Extracellular vesicles (EV) are microvesicles formed by the inversion of the phospholipid bilayer of different cellular subtypes and have been described as biomarkers of cellular damage, activation, and intercellular signaling in numerous clinical scenarios. We studied the association between the levels of EV and the incidence of acute GVHD (aGVHD). Forty patients undergoing allo-SCT for hematological malignancies had their plasma collected at neutrophil engraftment. Using flow cytometry combined with fluorescent beads, the total circulating EV count (TEV) was established with annexin V positivity; CD61 positivity was used for platelet-derived EV (PEV), and CD235 positivity, for erythrocyte-derived EV (EryEV). TEV counts greater than 516/μL were associated with a higher cumulative incidence (CI) of grade II to IV aGVHD (54% vs. 21%; p = 0.02), as were EryEV counts above 357 /μL (CI of aGVHD: 59% vs. 26%; p = 0.04). In patients who are exposed to reduced intensity conditioning (RIC), stronger associations of both high TEV and EryEV counts with aGVHD were observed (77% vs. 22%; p = 0.003 and 89% vs. 27%; p = 0.002, respectively). PEV levels were not associated with the risk of aGVHD. Our data suggest that the measurement of cell-derived EV at engraftment can be used as a preemptive biomarker for acute GVHD.

Multiple Roles of Glycans in Hematological Malignancies

The three types of blood cells (red blood cells for carrying oxygen, white blood cells for immune protection, and platelets for wound clotting) arise from hematopoietic stem/progenitor cells in the adult bone marrow, and function in physiological regulation and communication with local microenvironments to maintain systemic homeostasis. Hematological malignancies are relatively uncommon malignant disorders derived from the two major blood cell lineages: myeloid (leukemia) and lymphoid (lymphoma). Malignant clones lose their regulatory mechanisms, resulting in production of a large number of dysfunctional cells and destruction of normal hematopoiesis. Glycans are one of the four major types of essential biological macromolecules, along with nucleic acids, proteins, and lipids. Major glycan subgroups are N-glycans, O-glycans, glycosaminoglycans, and glycosphingolipids. Aberrant expression of glycan structures, resulting from dysregulation of glycan-related genes, is associated with cancer development and progression in terms of cell signaling and communication, tumor cell dissociation and invasion, cell-matrix interactions, tumor angiogenesis, immune modulation, and metastasis formation. Aberrant glycan expression occurs in most hematological malignancies, notably acute myeloid leukemia, myeloproliferative neoplasms, and multiple myeloma, etc. Here, we review recent research advances regarding aberrant glycans, their related genes, and their roles in hematological malignancies. Our improved understanding of the mechanisms that underlie aberrant patterns of glycosylation will lead to development of novel, more effective therapeutic approaches targeted to hematological malignancies.

Microparticles in Hematological Malignancies: Role in Coagulopathy and Tumor Pathogenesis

Microparticles (MP) are submicron vesicles released from various cells in response to activation, injury or apoptosis. They contain different structural and functional proteins and RNAs, which contribute to physiological intercellular "crosstalk" and to the pathogenesis of various diseases including cancer. In hematological malignancies, these MPs participate in the initiation and propagation of thrombosis through different pathways. They have a role in the angiogenesis, malignant cell survival and metastasis. MPs act as a mediator of resistance of leukemic cells to chemotherapy. The number of MPs is one of the prognostic factors following stem cell transplant, and studies have also found they contribute to the pathogenesis of graft versus host disease. MPs are being tested as therapeutic options in leukemias and graft versus host disease. Future studies should help us understand the interactions between MPs and cancer cells better, thereby opening new approaches for treatment of hematological malignancies.

Deciphering the role of ectosomes in cancer development and progression: focus on the proteome

Ectosomes are small heterogeneous membrane vesicles generated by budding from the plasma membrane in a variety of cell types and, more frequently, in tumor cells. They are shed into the extracellular space and are proposed as a novel form of intracellular communication in which information is transmitted from the originating cell to recipient cells without direct cell-to-cell contact. This review focuses on a single population of extracellular vesicles-ectosomes. We summarize recent studies of tumor-derived ectosomes which examine their biogenesis and protein cargo, and their influence on different aspects of cancer progression. We discuss possible clinical implications involving ectosomes as potential biomarkers, diagnostic tools and treatment targets in oncology. The unique composition of the molecules (cargo) that ectosomes carry, and their functional role, depends largely on the state of their originating cell. Through horizontal transfer of a variety of biologically active molecules (including proteins, lipids and nucleic acids) between donor and recipient cells, tumor-derived ectosomes may play functional roles in oncogenic transformation, tumor progression, invasion, metastasis, angiogenesis promotion, escape from immune surveillance, and drug resistance, thereby facilitating disease progression. The presence of tumor-derived ectosomes in body fluids such as the blood and urine of cancer patients makes them potentially useful prognostic and predictive biomarkers. Tumor-derived ectosomes also offer possible targets for multiple therapeutic strategies.