Platelet and extracellular vesicles in COVID-19 infection and its vaccines

Platelet-derived extracellular vesicles: emerging players in hemostasis and thrombosis

Platelets, long recognized for their role in hemostasis and thrombosis, have emerged as key players in a wide array of physiological and pathological processes through the release of platelet-derived extracellular vesicles (PEVs). These nanoscale vesicles, rich in bioactive molecules such as proteins, lipids, and nucleic acids, facilitate intercellular communication and influence processes ranging from angiogenesis and inflammation to immune modulation and tissue repair. PEVs, the most abundant extracellular vesicles in circulation, display procoagulant activity 50-100 times greater than activated platelets, underscoring their pivotal role in hemostasis and thrombosis. Recent research has unveiled their dual role in health and disease, highlighting their potential as diagnostic biomarkers and therapeutic vehicles. PEVs are implicated in cancer progression, autoimmune diseases, and infectious diseases, where they modulate tumor microenvironments, immune responses, and inflammatory pathways. Moreover, their ability to deliver therapeutic agents with high specificity and biocompatibility positions them as promising tools in regenerative medicine, drug delivery, and targeted therapies. This review comprehensively explores PEV biogenesis, cargo composition, and their multifaceted roles in hemostasis and thrombosis, as well as their broader implications in disease. It also explores the potential of PEVs as diagnostic markers and innovative therapeutic strategies, offering insights into their application in treating thrombotic disorders, cancer, and inflammatory diseases. Despite significant advancements, challenges remain in standardizing isolation protocols and translating preclinical findings into clinical applications. Unlocking the full potential of PEVs promises to revolutionize diagnostics and therapeutics, paving the way for novel approaches to managing complex diseases.

Bioprocessing of human platelet concentrates to generate lysates and extracellular vesicles for therapeutic applications

This work describes protocols for preparing specific forms of human platelet lysates from pooled platelet concentrates (PCs) and the isolation of platelet-derived extracellular vesicles (p-EVs). Clinical-grade PCs can be sourced from blood establishments immediately following expiration for transfusion use. Here, we describe methods to process PCs into specific lysates from which p-EVs can be isolated. Each lysate type is prepared using platelet activation and processing methods which produce distinct products that may be useful in different applications. For example, serum-converted platelet lysate (SCPL)-EVs were recently shown to have powerful therapeutic properties following myocardial infarction in mice. EVs can be isolated from all products using size exclusion chromatography, producing pure and consistent p-EVs from multiple batches. Together, these methods allow isolation of p-EVs with excellent potential for clinical and preclinical applications.•Platelet concentrates (PCs) obtained from local blood establishments are reliable and sustainable sources to generate biomaterials.•We outline five distinct methods of platelet lysate generation and one method for extracellular vesicle isolation.•Each platelet lysate form has different biological properties which may be suitable for certain applications.

COVID-19 vaccine adverse events: Evaluating the pathophysiology with an emphasis on sulfur metabolism and endotheliopathy

In this narrative review, we assess the pathophysiology of severe adverse events that presented after vaccination with DNA and mRNA vaccines against COVID-19. The focus is on the perspective of an undersulfated and degraded glycocalyx, considering its impact on immunomodulation, inflammatory responses, coagulation and oxidative stress. The paper explores various factors that lead to glutathione and inorganic sulfate depletion and their subsequent effect on glycocalyx sulfation and other metabolites, including hormones. Components of COVID-19 vaccines, such as DNA and mRNA material, spike protein antigen and lipid nanoparticles, are involved in possible cytotoxic effects. The common thread connecting these adverse events is endotheliopathy or glycocalyx degradation, caused by depleted glutathione and inorganic sulfate levels, shear stress from circulating nanoparticles, aggregation and formation of protein coronas; leading to imbalanced immune responses and chronic release of pro-inflammatory cytokines, ultimately resulting in oxidative stress and systemic inflammatory response syndrome. By understanding the underlying pathophysiology of severe adverse events, better treatment options can be explored.

Immunothrombosis: A bibliometric analysis from 2003 to 2023

BACKGROUND

Immunothrombosis is a physiological process that constitutes an intravascular innate immune response. Abnormal immunothrombosis can lead to thrombotic disorders. With the outbreak of COVID-19, there is increasing attention to the mechanisms of immunothrombosis and its critical role in thrombotic events, and a growing number of relevant research papers are emerging. This article employs bibliometrics to discuss the current status, hotspots, and trends in research of this field.

METHODS

Research papers relevant to immunothrombosis published from January 1, 2003, to May 29, 2023, were collected from the Web of Science Core Collection database. VOSviewer and the R package "Bibliometrix" were employed to analyze publication metrics, including the number of publications, authors, countries, institutions, journals, and keywords. The analysis generated visual results, and trends in research topics and hotspots were examined.

RESULTS

A total of 495 target papers were identified, originating from 58 countries and involving 3287 authors from 1011 research institutions. Eighty high-frequency keywords were classified into 5 clusters. The current key research topics in the field of immunothrombosis include platelets, inflammation, neutrophil extracellular traps, Von Willebrand factor, and the complement system. Research hotspots focus on the mechanisms and manifestations of immunothrombosis in COVID-19, as well as the discovery of novel treatment strategies targeting immunothrombosis in cardiovascular and cerebrovascular diseases.

CONCLUSION

Bibliometric analysis summarizes the main achievements and development trends in research on immunothrombosis, offering readers a comprehensive understanding of the field and guiding future research directions.

Flow cytometry for extracellular vesicle characterization in COVID-19 and post-acute sequelae of SARS-CoV-2 infection

Infection with SARS-CoV-2, the virus responsible for COVID-19 diseases, can impact different tissues and induce significant cellular alterations. The production of extracellular vesicles (EVs), which are physiologically involved in cell communication, is also altered during COVID-19, along with the dysfunction of cytoplasmic organelles. Since circulating EVs reflect the state of their cells of origin, they represent valuable tools for monitoring pathological conditions. Despite challenges in detecting EVs due to their size and specific cellular compartment origin using different methodologies, flow cytometry has proven to be an effective method for assessing the role of EVs in COVID-19. This review summarizes the involvement of plasmatic EVs in COVID-19 patients and individuals with Long COVID (LC) affected by post-acute sequelae of SARS-CoV-2 infection (PASC), highlighting their dual role in exerting both pro- and antiviral effects. We also emphasize how flow cytometry, with its multiparametric approach, can be employed to characterize circulating EVs, particularly in infectious diseases such as COVID-19, and suggest their potential role in chronic impairments during post-infection.

Extracellular Vesicles: The Invisible Heroes and Villains of COVID-19 Central Neuropathology

Acknowledging the neurological symptoms of COVID-19 and the long-lasting neurological damage even after the epidemic ends are common, necessitating ongoing vigilance. Initial investigations suggest that extracellular vesicles (EVs), which assist in the evasion of the host's immune response and achieve immune evasion in SARS-CoV-2 systemic spreading, contribute to the virus's attack on the central nervous system (CNS). The pro-inflammatory, pro-coagulant, and immunomodulatory properties of EVs contents may directly drive neuroinflammation and cerebral thrombosis in COVID-19. Additionally, EVs have attracted attention as potential candidates for targeted therapy in COVID-19 due to their innate homing properties, low immunogenicity, and ability to cross the blood-brain barrier (BBB) freely. Mesenchymal stromal/stem cell (MSCs) secreted EVs are widely applied and evaluated in patients with COVID-19 for their therapeutic effect, considering the limited antiviral treatment. This review summarizes the involvement of EVs in COVID-19 neuropathology as carriers of SARS-CoV-2 or other pathogenic contents, as predictors of COVID-19 neuropathology by transporting brain-derived substances, and as therapeutic agents by delivering biotherapeutic substances or drugs. Understanding the diverse roles of EVs in the neuropathological aspects of COVID-19 provides a comprehensive framework for developing, treating, and preventing central neuropathology and the severe consequences associated with the disease.

Platelet-derived extracellular vesicles for drug delivery

Platelet-derived extracellular vesicles (PEVs) are a subset of EVs that are released from platelets, which are small nuclear cell fragments that play a critical role in hemostasis and thrombosis. PEVs have been shown to have important roles in a variety of physiological and pathological processes, including inflammation, angiogenesis, and cancer. Recently, researchers, including our group have utilized PEVs as drug delivery platforms as PEVs could target inflammatory sites both passively and actively. This review summarizes the biological function of PEVs, introduces recent applications of PEVs in targeted drug delivery, and provides an outlook for the further development of utilizing PEVs for drug delivery.

Advances in Purification, Modification, and Application of Extracellular Vesicles for Novel Clinical Treatments

Extracellular vesicles (EV) are membrane vesicles surrounded by a lipid bilayer membrane and include microvesicles, apoptotic bodies, exosomes, and exomeres. Exosome-encapsulated microRNAs (miRNAs) released from cancer cells are involved in the proliferation and metastasis of tumor cells via angiogenesis. On the other hand, mesenchymal stem cell (MSC) therapy, which is being employed in regenerative medicine owing to the ability of MSCs to differentiate into various cells, is due to humoral factors, including messenger RNA (mRNA), miRNAs, proteins, and lipids, which are encapsulated in exosomes derived from transplanted cells. New treatments that advocate cell-free therapy using MSC-derived exosomes will significantly improve clinical practice. Therefore, using highly purified exosomes that perform their original functions is desirable. In this review, we summarized advances in the purification, modification, and application of EVs as novel strategies to treat some diseases.

The Role of Extracellular Vesicles in COVID-19 Pathology

Extracellular vesicles (EVs) have become a trending topic in recent years; they constitute a new intercellular communication paradigm. Extracellular vesicles are 30–4000 nanometers in diameter particles that are limited by a phospholipid bilayer and contain functional biomolecules, such as proteins, lipids, and nucleic acids. They are released by virtually all types of eukaryotic cells; through their cargoes, EVs are capable of triggering signaling in recipient cells. In addition to their functions in the homeostatic state, EVs have gained attention because of their roles in pathological contexts, eventually contributing to disease progression. In the Coronavirus disease 2019 (COVID-19) pandemic, aside from the scientific race for the development of preventive and therapeutic interventions, it is critical to understand the pathological mechanisms involved in SARS-CoV-2 infection. In this sense, EVs are key players in the main processes of COVID-19. Thus, in this review, we highlight the role of EVs in the establishment of the viral infection and in the procoagulant state, cytokine storm, and immunoregulation of innate and adaptive immune responses.

SARS-CoV-2 and cancer: the intriguing and informative cross-talk

The COVID-19 pandemic caused by the SARS-CoV-2 virus has significantly disrupted and burdened the diagnostic workup and delivery of care, including transfusion, to cancer patients across the globe. Furthermore, cancer patients suffering from solid tumors or hematologic malignancies were more prone to the infection and had higher morbidity and mortality than the rest of the population. Major signaling pathways have been identified at the intersection of SARS-CoV-2 and cancer cells, often leading to tumor progression or alteration of the tumor response to therapy. The reactivation of oncogenic viruses has also been alluded to in the context and following COVID-19. Paradoxically, certain tumors responded better following the profound infection-induced immune modulation. Unveiling the mechanisms of the virus-tumor cell interactions will lead to a better understanding of the pathophysiology of both cancer progression and virus propagation. It would be challenging to monitor, through the different cancer registries, retrospectively, the response of patients who have been previously exposed to the virus in contrast to those who have not contracted the infection.

The Role of Platelet-Derived Extracellular Vesicles in Immune-Mediated Thrombosis

Platelet-derived extracellular vesicles (PEVs) play important roles in hemostasis and thrombosis. There are three major types of PEVs described based on their size and characteristics, but newer types may continue to emerge owing to the ongoing improvement in the methodologies and terms used to define various types of EVs. As the literature on EVs is growing, there are continuing attempts to standardize protocols for EV isolation and reach consensus in the field. This review provides information on mechanisms of PEV production, characteristics, cellular interaction, and their pathological role, especially in autoimmune and infectious diseases. We also highlight the mechanisms through which PEVs can activate parent cells in a feedback loop.