COVID-19 and Extracellular Vesicles: An Intriguing Interplay

INDUCED PLURIPOTENT STEM CELL-DERIVED MESENCHYMAL STEM CELLS-DERIVED EXTRACELLULAR VESICLES ATTENUATE LPS-INDUCED LUNG INJURY AND ENDOTOXEMIA IN MICE

ABSTRACT

Introduction: We hypothesized extracellular vesicles (EVs) from preconditioned human-induced pluripotent stem cell-derived mesenchymal stem cells (iMSCs) attenuate LPS-induced acute lung injury (ALI) and endotoxemia. Methods: iMSCs were incubated with cell stimulation cocktail (CSC) and EVs were isolated. iMSC-EVs were characterized by size and EV markers. Biodistribution of intratracheal (IT), intravenous, and intraperitoneal injection of iMSC-EVs in mice was examined using IVIS. Uptake of iMSC-EVs in lung tissue, alveolar macrophages, and RAW264.7 cells was also assessed. C57BL/6 mice were treated with IT/IP iMSC-EVs or vehicle ± IT/IP LPS to induce ALI/acute respiratory distress syndrome and endotoxemia. Lung tissues, plasma, and bronchoalveolar lavage fluid (BALF) were harvested at 24 h. Lung histology, BALF neutrophil/macrophage, cytokine levels, and total protein concentration were measured to assess ALI and inflammation. Survival studies were performed using IP LPS in mice for 3 days. Results: iMSC-EV route of administration resulted in differential tissue distribution. iMSC-EVs were taken up by alveolar macrophages in mouse lung and cultured RAW264.7 cells. IT LPS-treated mice demonstrated marked histologic ALI, increased BALF neutrophils/macrophages and protein, and increased BALF and plasma TNF-α/IL-6 levels. These parameters were attenuated by 2 h before or 2 h after treatment with IT iMSC-EVs in ALI mice. Interestingly, the IT LPS-induced increase in IL-10 was augmented by iMSC-EVs. Mice treated with IP LPS showed increases in TNF-α and IL-6 that were downregulated by iMSC-EVs and LPS-induced mortality was ameliorated by iMSC-EVs. Administration of IT iMSC-EVs 2 h after LPS downregulated the increase in proinflammatory cytokines (TNF-α/IL-6) by LPS and further increased IL-10 levels. Conclusions: iMSC-EVs attenuate the inflammatory effects of LPS on cytokine levels in ALI and IP LPS in mice. LPS-induced mortality was improved with administration of iMSC-EVs.

Exosomes, and the potential for exosome-based interventions against COVID-19

Since late 2019, the world has been devastated by the coronavirus disease 2019 (COVID-19) induced by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), with more than 760 million people affected and ∼seven million deaths reported. Although effective treatments for COVID-19 are currently limited, there has been a strong focus on developing new therapeutic approaches to address the morbidity and mortality linked to this disease. An approach that is currently being investigated is the use of exosome-based therapies. Exosomes are small, extracellular vesicles that play a role in many clinical diseases, including viral infections, infected cells release exosomes that can transmit viral components, such as miRNAs and proteins, and can also include receptors for viruses that facilitate viral entry into recipient cells. SARS-CoV-2 has the ability to impact the formation, secretion, and release of exosomes, thereby potentially facilitating or intensifying the transmission of the virus among cells, tissues and individuals. Therefore, designing synthetic exosomes that carry immunomodulatory cargo and antiviral compounds are proposed to be a promising strategy for the treatment of COVID-19 and other viral diseases. Moreover, exosomes generated from mesenchymal stem cells (MSC) might be employed as cell-free therapeutic agents, as MSC-derived exosomes can diminish the cytokine storm and reverse the suppression of host anti-viral defences associated with COVID-19, and boost the repair of lung damage linked to mitochondrial activity. The present article discusses the significance and roles of exosomes in COVID-19, and explores potential future applications of exosomes in combating this disease. Despite the challenges posed by COVID-19, exosome-based therapies could represent a promising avenue for improving patient outcomes and reducing the impact of this disease.

MicroRNA Nano-Shuttles: Engineering Extracellular Vesicles as a Cutting-Edge Biotechnology Platform for Clinical Use in Therapeutics

Extracellular vesicles (EVs) are nano-sized, membranous transporters of various active biomolecules with inflicting phenotypic capabilities, that are naturally secreted by almost all cells with a promising vantage point as a potential leading drug delivery platform. The intrinsic characteristics of their low toxicity, superior structural stability, and cargo loading capacity continue to fuel a multitude of research avenues dedicated to loading EVs with therapeutic and diagnostic cargos (pharmaceutical compounds, nucleic acids, proteins, and nanomaterials) in attempts to generate superior natural nanoscale delivery systems for clinical application in therapeutics. In addition to their well-known role in intercellular communication, EVs harbor microRNAs (miRNAs), which can alter the translational potential of receiving cells and thus act as important mediators in numerous biological and pathological processes. To leverage this potential, EVs can be structurally engineered to shuttle therapeutic miRNAs to diseased recipient cells as a potential targeted 'treatment' or 'therapy'. Herein, this review focuses on the therapeutic potential of EV-coupled miRNAs; summarizing the biogenesis, contents, and function of EVs, as well as providing both a comprehensive discussion of current EV loading techniques and an update on miRNA-engineered EVs as a next-generation platform piloting benchtop studies to propel potential clinical translation on the forefront of nanomedicine.

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.

Lipid Metabolism Modulation during SARS-CoV-2 Infection: A Spotlight on Extracellular Vesicles and Therapeutic Prospects

Extracellular vesicles (EVs) have a significant impact on the pathophysiological processes associated with various diseases such as tumors, inflammation, and infection. They exhibit molecular, biochemical, and entry control characteristics similar to viral infections. Viruses, on the other hand, depend on host metabolic machineries to fulfill their biosynthetic requirements. Due to potential advantages such as biocompatibility, biodegradation, and efficient immune activation, EVs have emerged as potential therapeutic targets against the SARS-CoV-2 infection. Studies on COVID-19 patients have shown that they frequently have dysregulated lipid profiles, which are associated with an increased risk of severe repercussions. Lipid droplets (LDs) serve as organelles with significant roles in lipid metabolism and energy homeostasis as well as having a wide range of functions in infections. The down-modulation of lipids, such as sphingolipid ceramide and eicosanoids, or of the transcriptional factors involved in lipogenesis seem to inhibit the viral multiplication, suggesting their involvement in the virus replication and pathogenesis as well as highlighting their potential as targets for drug development. Hence, this review focuses on the role of modulation of lipid metabolism and EVs in the mechanism of immune system evasion during SARS-CoV-2 infection and explores the therapeutic potential of EVs as well as application for delivering therapeutic substances to mitigate viral infections.

CEA vaccines

Carcinoembryonic antigen (CEA) is a glycosylated cell surface oncofetal protein involved in adhesion, proliferation, and migration that is highly upregulated in multiple carcinomas and has long been a promising target for cancer vaccination. This review summarizes the progress to date in the development of CEA vaccines, examining both pre-clinical and clinical studies across a variety of vaccine platforms that in aggregate, begin to reveal some critical insights. These studies demonstrate the ability of CEA vaccines to break immunologic tolerance and elicit CEA-specific immunity, which associates with improved clinical outcomes in select individuals. Approaches that have combined replicating viral vectors, with heterologous boosting and different adjuvant strategies have been particularly promising but, these early clinical trial results will require confirmatory studies. Collectively, these studies suggest that clinical efficacy likely depends upon harnessing a potent vaccine combination in an appropriate clinical setting to fully realize the potential of CEA vaccination.

Exosomes: Promising Delivery Tools for Overcoming Blood-Brain Barrier and Glioblastoma Therapy

Gliomas make up virtually 80% of all lethal primary brain tumors and are categorized based on their cell of origin. Glioblastoma is an astrocytic tumor that has an inferior prognosis despite the ongoing advances in treatment modalities. One of the main reasons for this shortcoming is the presence of the blood-brain barrier and blood-brain tumor barrier. Novel invasive and non-invasive drug delivery strategies for glioblastoma have been developed to overcome both the intact blood-brain barrier and leverage the disrupted nature of the blood-brain tumor barrier to target cancer cells after resection-the first treatment stage of glioblastoma. Exosomes are among non-invasive drug delivery methods and have emerged as a natural drug delivery vehicle with high biological barrier penetrability. There are various exosome isolation methods from different origins, and the intended use of the exosomes and starting materials defines the choice of isolation technique. In the present review, we have given an overview of the structure of the blood-brain barrier and its disruption in glioblastoma. This review provided a comprehensive insight into novel passive and active drug delivery techniques to overcome the blood-brain barrier, emphasizing exosomes as an excellent emerging drug, gene, and effective molecule delivery vehicle used in glioblastoma therapy.

Circulating microRNAs as emerging regulators of COVID-19

Coronavirus disease 2019 (COVID-19), an infectious disease caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), is a global pandemic that has high incidence rates, spreads rapidly, and has caused more than 6.5 million deaths globally to date. Currently, several drugs have been used in the clinical treatment of COVID-19, including antivirals (e.g., molnupiravir, baricitinib, and remdesivir), monoclonal antibodies (e.g., etesevimab and tocilizumab), protease inhibitors (e.g., paxlovid), and glucocorticoids (e.g., dexamethasone). Increasing evidence suggests that circulating microRNAs (miRNAs) are important regulators of viral infection and antiviral immune responses, including the biological processes involved in regulating COVID-19 infection and subsequent complications. During viral infection, both viral genes and host cytokines regulate transcriptional and posttranscriptional steps affecting viral replication. Virus-encoded miRNAs are a component of the immune evasion repertoire and function by directly targeting immune functions. Moreover, several host circulating miRNAs can contribute to viral immune escape and play an antiviral role by not only promoting nonstructural protein (nsp) 10 expression in SARS coronavirus, but among others inhibiting NOD-like receptor pyrin domain-containing (NLRP) 3 and IL-1β transcription. Consequently, understanding the expression and mechanism of action of circulating miRNAs during SARS-CoV-2 infection will provide unexpected insights into circulating miRNA-based studies. In this review, we examined the recent progress of circulating miRNAs in the regulation of severe inflammatory response, immune dysfunction, and thrombosis caused by SARS-CoV-2 infection, discussed the mechanisms of action, and highlighted the therapeutic challenges involving miRNA and future research directions in the treatment of COVID-19.

COVID-19-Induced Stroke and the Potential of Using Mesenchymal Stem Cells-Derived Extracellular Vesicles in the Regulation of Neuroinflammation

Ischemic stroke (IS) is a known neurological complication of COVID-19 infection, which is associated with high mortality and disability. Following IS, secondary neuroinflammation that occurs can play both harmful and beneficial roles and lead to further injury or repair of damaged neuronal tissue, respectively. Since inflammation plays a pivotal role in the pathogenesis of COVID-19-induced stroke, targeting neuroinflammation could be an effective strategy for modulating the immune responses following ischemic events. Numerous investigations have indicated that the application of mesenchymal stem cells-derived extracellular vesicles (MSC-EVs) improves functional recovery following stroke, mainly through reducing neuroinflammation as well as promoting neurogenesis and angiogenesis. Therefore, MSC-EVs can be applied for the regulation of SARS-CoV-2-mediated inflammation and the management of COVID-19- related ischemic events. In this study, we have first described the advantages and disadvantages of neuroinflammation in the pathological evolution after IS and summarized the characteristics of neuroinflammation in COVID-19-related stroke. Then, we have discussed the potential benefit of MSC-EVs in the regulation of inflammatory responses after COVID-19-induced ischemic events.

Caveolae-Mediated Extracellular Vesicle (CMEV) Signaling of Polyvalent Polysaccharide Vaccination: A Host-Pathogen Interface Hypothesis

We published a study showing that improvement in response to splenectomy associated defective, in regards to the antibody response to Pneumovax^® 23 (23-valent polysaccharides, PPSV23), can be achieved by splenocyte reinfusion. This study triggered a debate on whether and how primary and secondary immune responses occur based on humoral antibody responses to the initial vaccination and revaccination. The anti-SARS-CoV-2 vaccine sheds new light on the interpretation of our previous data. Here, we offer an opinion on the administration of the polyvalent polysaccharide vaccine (PPSV23), which appears to be highly relevant to the primary vaccine against SARS-CoV-2 and its booster dose. Thus, we do not insist this is a secondary immune response but an antibody response, nonetheless, as measured through IgG titers after revaccination. However, we contend that we are not sure if these lower but present IgG levels against pneumococcal antigens are clinically protective or are equally common in all groups because of the phenomenon of "hyporesponsiveness" seen after repeated polysaccharide vaccine challenge. We review the literature and propose a new mechanism-caveolae memory extracellular vesicles (CMEVs)-by which polysaccharides mediate prolonged and sustained immune response post-vaccination. We further delineate and explain the data sets to suggest that the dual targets on both Cav-1 and SARS-CoV-2 spike proteins may block the viral entrance and neutralize viral load, which minimizes the immune reaction against viral attacks and inflammatory responses. Thus, while presenting our immunological opinion, we answer queries and responses made by readers to our original statements published in our previous work and propose a hypothesis for all vaccination strategies, i.e., caveolae-mediated extracellular vesicle-mediated vaccine memory.

Nanoparticle-Based Delivery Systems for Vaccines

Vaccination is still the most cost-effective way to combat infectious illnesses. Conventional vaccinations may have low immunogenicity and, in most situations, only provide partial protection. A new class of nanoparticle-based vaccinations has shown considerable promise in addressing the majority of the shortcomings of traditional and subunit vaccines. This is due to recent breakthroughs in chemical and biological engineering, which allow for the exact regulation of nanoparticle size, shape, functionality, and surface characteristics, resulting in improved antigen presentation and robust immunogenicity. A blend of physicochemical, immunological, and toxicological experiments can be used to accurately characterize nanovaccines. This narrative review will provide an overview of the current scenario of the nanovaccine.

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.

Potential Cell-Based and Cell-Free Therapy for Patients with COVID-19

Since it was first reported, the novel coronavirus disease 2019 (COVID-19) remains an unresolved puzzle for biomedical researchers in different fields. Various treatments, drugs, and interventions were explored as treatments for COVID. Nevertheless, there are no standard and effective therapeutic measures. Meanwhile, mesenchymal stem cell (MSC) therapy offers a new approach with minimal side effects. MSCs and MSC-based products possess several biological properties that potentially alleviate COVID-19 symptoms. Generally, there are three classifications of stem cell therapy: cell-based therapy, tissue engineering, and cell-free therapy. This review discusses the MSC-based and cell-free therapies for patients with COVID-19, their potential mechanisms of action, and clinical trials related to these therapies. Cell-based therapies involve the direct use and injection of MSCs into the target tissue or organ. On the other hand, cell-free therapy uses secreted products from cells as the primary material. Cell-free therapy materials can comprise cell secretomes and extracellular vesicles. Each therapeutic approach possesses different benefits and various risks. A better understanding of MSC-based and cell-free therapies is essential for supporting the development of safe and effective COVID-19 therapy.

Early but reversible haemostatic changes in a-symptomatic females expressing COVID-19 antibodies

The coronavirus, COVID-19 pandemic spread across the globe in 2020, with an initial high case mortality in those requiring intensive care treatment due to serious complication. A vaccine programme was quickly developed and currently the UK is one of highest double vaccinated and boosted countries in the world. Despite tremendous efforts by the UK, new cases of COVID-19 are still occurring, due to viral mutation. A major problem associated with COVID-19 is the large a-symptomatic spread within the population. Little investigation into the a-symptomatic population has been carried out and therefore we pose that the residual effects of a-symptomatic infection is still largely unknown. Prior to mass vaccination, a multi-phased single cohort study of IgM and IgG COVID-19 antibody prevalence and the associated haemostatic changes were assessed in a Welsh cohort of 739 participants, at three time points. Positive antibody participants with age and gender matched negative antibody controls were assessed at 0, 3 and 6 months. Antibody positive females appeared to have lower antibody responses in comparison to their a-symptomatic male counterparts. Despite this initial testing showed a unique significant increase in TRAP-6-induced platelet aggregation, prothrombin time (PT) and clot initiation time. Despite coagulation parameters beginning to return to normal at 3 months, significant decreases are observed in both haemoglobin and haematocrit levels. The production of extracellular vesicles (EV) was also determined in this study. Although the overall number of EV does not change throughout the study, at the initial 0 months' time point a significant increase in the percentage of circulating pro-coagulant platelet derived EV is seen, which does not appear to be related to the extent of platelet activation in the subject. We conclude that early, but reversible changes in haemostatic pathways within the a-symptomatic, female, antibody positive COVID-19 individuals are present. These changes may be key in identifying a period of pro-coagulative risk for a-symptomatic female patients.

Proteomic Profile of Procoagulant Extracellular Vesicles Reflects Complement System Activation and Platelet Hyperreactivity of Patients with Severe COVID-19

Background

Extracellular vesicles (EVs) are a valuable source of biomarkers and display the pathophysiological status of various diseases. In COVID-19, EVs have been explored in several studies for their ability to reflect molecular changes caused by SARS-CoV-2. Here we provide insights into the roles of EVs in pathological processes associated with the progression and severity of COVID-19.

Methods

In this study, we used a label-free shotgun proteomic approach to identify and quantify alterations in EV protein abundance in severe COVID-19 patients. We isolated plasma extracellular vesicles from healthy donors and patients with severe COVID-19 by size exclusion chromatography (SEC). Then, flow cytometry was performed to assess the origin of EVs and to investigate the presence of circulating procoagulant EVs in COVID-19 patients. A total protein extraction was performed, and samples were analyzed by nLC-MS/MS in a Q-Exactive HF-X. Finally, computational analysis was applied to signify biological processes related to disease pathogenesis.

Results

We report significant changes in the proteome of EVs from patients with severe COVID-19. Flow cytometry experiments indicated an increase in total circulating EVs and with tissue factor (TF) dependent procoagulant activity. Differentially expressed proteins in the disease groups were associated with complement and coagulation cascades, platelet degranulation, and acute inflammatory response.

Conclusions

The proteomic data reinforce the changes in the proteome of extracellular vesicles from patients infected with SARS-CoV-2 and suggest a role for EVs in severe COVID-19.

Preclinical Studies on Convalescent Human Immune Plasma-Derived Exosome: Omics and Antiviral Properties to SARS-CoV-2

The scale of the COVID-19 pandemic forced urgent measures for the development of new therapeutics. One of these strategies is the use of convalescent plasma (CP) as a conventional source for passive immunity. Recently, there has been interest in CP-derived exosomes. In this report, we present a structural, biochemical, and biological characterization of our proprietary product, convalescent human immune plasma-derived exosome (ChipEXO), following the guidelines set forth by the Turkish Ministry of Health and the Turkish Red Crescent, the Good Manufacturing Practice, the International Society for Extracellular Vesicles, and the Gene Ontology Consortium. The data support the safety and efficacy of this product against SARS-CoV-2 infections in preclinical models.

Regenerative therapy by using Mesenchymal Stem Cells-derived exosomes in COVID-19 treatment. The potential role and underlying mechanisms

COVID-19 disease caused by the Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2), started in December 2019 in Wuhan, China, and quickly became the global pandemic. The high spread rate, relatively high mortality rate, and the lack of specific medicine have led researchers and clinicians worldwide to find new treatment strategies. Unfortunately, evidence shows that the virus-specific receptor Angiotensin-Converting Enzyme 2 (ACE-2) is present on the surface of most cells in the body, leading to immune system dysfunction and multi-organ failure in critically ill patients. In this context, the use of Mesenchymal Stem Cells (MSCs) and their secret has opened new therapeutic horizons for patients due to the lack of ACE2 receptor expression. MSCs exert their beneficial therapeutic actions, particularly anti-inflammatory and immunomodulatory properties, mainly through paracrine effects which are mediated by exosomes. Exosomes are bilayer nanovesicles that carry a unique cargo of proteins, lipids and functional nucleic acids based on their cell origin. This review article aims to investigate the possible role of exosomes and the underlying mechanism involved in treating COVID-19 disease based on recent findings.

Unraveling the Proteomic Landscape of Intestinal Epithelial Cell-Derived Exosomes in Mice

Purpose

This study aimed to identify the biological functions of small intestine intestinal epithelial cell derived exosomes (IEC-Exos) and further distinguished the difference proteins in IEC-Exos between ileum and jejunum related to function of the digestive system and occurrence of several diseases.

Materials and Methods

IECs of Male C57BL/6J mice were isolated. IEC-Exos were extracted from jejunum and ileum epithelial cell culture fluid by ultracentrifugation. In addition, isobaric tags for relative and absolute quantitation (iTRAQ) combined with liquid chromatography-tandem mass spectrometry (LC-MS/MS) were used to detect IEC-Exo proteins and conduct biological information analysis.

Results

The results showed that compared with jejunum IEC-Exos from ileum IEC-Exos, there were 393 up-regulated proteins and 346 down-regulated proteins. IECs-Exos, especially derived from jejunum, were rich in angiotensin-converting enzyme 2 (ACE2). The highly expressed proteins from ileum IEC-Exos were mostly enriched in genetic information processing pathways, which mainly mediate the processes of bile acid transport, protein synthesis and processing modification. In contrast, the highly expressed proteins from jejunum IEC-Exos were mainly enriched in metabolic pathways involved in sugar, fatty acid, amino acid, drug, and bone metabolism, etc. The differentially expressed proteins between ileum and jejunum IEC-Exos were not only related to the function of the digestive system but also closely related to the occurrence of infectious diseases, endocrine diseases and osteoarthritis, etc.

Conclusion

IEC-Exos there were many differentially expressed proteins between ileum and jejunum, which played different roles in regulating intestinal biological functions. ACE2, the main host cell receptor of SARS-CoV-2, was highly expressed in IEC-Exos, which indicated that IEC-Exos may be a potential route of SARS-CoV-2 infection.

Isolation of Extracellular Vesicles From Microalgae: A Renewable and Scalable Bioprocess

Extracellular vesicles (EVs) play a crucial role as potent signal transducers among cells, with the potential to operate cross-species and cross-kingdom communication. Nanoalgosomes are a subtype of EVs recently identified and isolated from microalgae. Microalgae represent a natural bioresource with the capacity to produce several secondary metabolites with a broad range of biological activities and commercial applications. The present study highlights the upstream and downstream processes required for the scalable production of nanoalgosomes from cultures of the marine microalgae Tetraselmis chuii. Different technical parameters, protocols, and conditions were assessed to improve EVs isolation by tangential flow filtration (TFF), aiming to enhance sample purity and yield. The optimization of the overall bioprocess was enhanced by quality control checks operated through robust biophysical and biochemical characterizations. Further, we showed the possibility of recycling by TFF microalgae cells post-EVs isolation for multiple EV production cycles. The present results highlight the potential of nanoalgosome production as a scalable, cost-effective bioprocess suitable for diverse scientific and industrial exploitations.

Generation of Spike-Extracellular Vesicles (S-EVs) as a Tool to Mimic SARS-CoV-2 Interaction with Host Cells

Extracellular vesicles (EVs) and viruses share common features: size, structure, biogenesis and uptake. In order to generate EVs expressing the SARS-CoV-2 spike protein on their surface (S-EVs), we collected EVs from SARS-CoV-2 spike expressing human embryonic kidney (HEK-293T) cells by stable transfection with a vector coding for the S1 and S2 subunits. S-EVs were characterized using nanoparticle tracking analysis, ExoView and super-resolution microscopy. We obtained a population of EVs of 50 to 200 nm in size. Spike expressing EVs represented around 40% of the total EV population and co-expressed spike protein with tetraspanins on the surfaces of EVs. We subsequently used ACE2-positive endothelial and bronchial epithelial cells for assessing the internalization of labeled S-EVs using a cytofluorimetric analysis. Internalization of S-EVs was higher than that of control EVs from non-transfected cells. Moreover, S-EV uptake was significantly decreased by anti-ACE2 antibody pre-treatment. Furthermore, colchicine, a drug currently used in clinical trials, significantly reduced S-EV entry into the cells. S-EVs represent a simple, safe, and scalable model to study host-virus interactions and the mechanisms of novel therapeutic drugs.

Small Extracellular Vesicles and COVID19-Using the "Trojan Horse" to Tackle the Giant

The COVID-19 pandemic is a global challenge, demanding researchers address different approaches in relation to prevention, diagnostics and therapeutics. Amongst the many tactics of tackling these therapeutic challenges, small extracellular vesicles (sEVs) or exosomes are emerging as a new frontier in the field of ameliorating viral infections. Exosomes are part of extracellular vesicles (EVs)-spherical biological structures with a lipid bilayer of a diameter of up to 5000 nm, which are released into the intercellular space by most types of eukaryotic cells, both in physiological and pathological states. EVs share structural similarities to viruses, such as small size, common mechanisms of biogenesis and mechanisms for cell entry. The role of EVs in promoting the viral spread by evading the immune response of the host, which is exhibited by retroviruses, indicates the potential for further investigation and possible manipulation of these processes when tackling the spread and treatment of COVID-19. The following paper introduces the topic of the use of exosomes in the treatment of viral infections, and presents the future prospects for the use of these EVs.

Racial Health Disparity and COVID-19

The infection by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) and resultant coronavirus diseases-19 (COVID-19) disproportionally affects minorities, especially African Americans (AA) compared to the Caucasian population. The AA population is disproportionally affected by COVID-19, in part, because they have high prevalence of underlying conditions such as obesity, diabetes, and hypertension, which are known to exacerbate not only kidney diseases, but also COVID-19. Further, a decreased adherence to COVID-19 guidelines among tobacco smokers could result in increased infection, inflammation, reduced immune response, and lungs damage, leading to more severe form of COVID-19. As a result of high prevalence of underlying conditions that cause kidney diseases in the AA population coupled with tobacco smoking make the AA population vulnerable to severe form of both COVID-19 and kidney diseases. In this review, we describe how tobacco smoking interact with SARS-CoV-2 and exacerbates SARS-CoV-2-induced kidney diseases including renal failure, especially in the AA population. We also explore the role of extracellular vesicles (EVs) in COVID-19 patients who smoke tobacco. EVs, which play important role in tobacco-mediated pathogenesis in infectious diseases, have also shown to be important in COVID-19 pathogenesis and organ injuries including kidney. Further, we explore the potential role of EVs in biomarker discovery and therapeutics, which may help to develop early diagnosis and treatment of tobacco-induced renal injury in COVID-19 patients, respectively.

Mesenchymal stromal cell-derived extracellular vesicles reduce lung inflammation and damage in nonclinical acute lung injury: Implications for COVID-19

Mesenchymal stem cell derived extracellular vesicles (MSC-EVs) are bioactive particles that evoke beneficial responses in recipient cells. We identified a role for MSC-EV in immune modulation and cellular salvage in a model of SARS-CoV-2 induced acute lung injury (ALI) using pulmonary epithelial cells and exposure to cytokines or the SARS-CoV-2 receptor binding domain (RBD). Whereas RBD or cytokine exposure caused a pro-inflammatory cellular environment and injurious signaling, impairing alveolar-capillary barrier function, and inducing cell death, MSC-EVs reduced inflammation and reestablished target cell health. Importantly, MSC-EV treatment increased active ACE2 surface protein compared to RBD injury, identifying a previously unknown role for MSC-EV treatment in COVID-19 signaling and pathogenesis. The beneficial effect of MSC-EV treatment was confirmed in an LPS-induced rat model of ALI wherein MSC-EVs reduced pro-inflammatory cytokine secretion and respiratory dysfunction associated with disease. MSC-EV administration was dose-responsive, demonstrating a large effective dose range for clinical translation. These data provide direct evidence of an MSC-EV-mediated improvement in ALI and contribute new insights into the therapeutic potential of MSC-EVs in COVID-19 or similar pathologies of respiratory distress.

Extracellular Vesicles: A New Paradigm for Cellular Communication in Perioperative Medicine, Critical Care, and Pain Management

Extracellular vesicles (EVs) play critical roles in many health and disease states, including ischemia, inflammation, and pain, which are major concerns in the perioperative period and in critically ill patients. EVs are functionally active, nanometer-sized, membrane-bound vesicles actively secreted by all cells. Cell signaling is essential to physiological and pathological processes, and EVs have recently emerged as key players in intercellular communication. Recent studies in EV biology have improved our mechanistic knowledge of the pathophysiological processes in perioperative and critical care patients. Studies also show promise in using EVs in novel diagnostic and therapeutic clinical applications. This review considers the current advances and gaps in knowledge of EVs in the areas of ischemia, inflammation, pain, and in organ systems that are most relevant to anesthesiology, perioperative medicine, critical care, and pain management. We expect the reader will better understand the relationship between EVs and perioperative and critical care pathophysiological states and their potential use as novel diagnostic and therapeutic modalities.

Nanomaterials Upscaling Cell Production and Advancing Exosome-Based Stem Cell Therapies

The COVID-19 pandemic underlined that by investing in both basic and clinical life science research and if there are enough volunteers, it is feasible to have -validated by Phase III clinical trials- vaccines in less than a year. Regarding the treatment options for the people who were infected by COVID-19, we know that it was the large clinical trials - like SOLIDARITY (WHO) and RECOVERY (UK)- that gave the most valid results, and that although hundreds of drugs were repurposed, sadly, most proved to be unsuccessful. Repurposing drugs and compassionate use, were the only options for the first half of 2020. The same applied to the convalescent plasma (CP) approach; however, apart from CP, other cell derived therapeutics were deployed, such as synthetic monoclonal antibodies, which were also tested and given provisional licences by health authorities. Unfortunately, synthetic antibody production comes with problems related to low and slow yield that were not overcome, while SARS-CoV-2 viral mutations may possibly render them less effective. One approach that works and is currently assessed in several clinical trials, is mesenchymal stromal cell (MSCs) and extracellular vesicle (EV) administration for therapy. Interdisciplinarity may prove key here. Easy to produce nanomaterials and biomaterials should be further investigated to increase bioproduction of MSCs, both at the level of therapeutics, as the base substrate for EV production and to upscale synthetic antibody production for therapy.

Role of Extracellular Vesicles in Cell Death and Inflammation

Extracellular vesicles (EVs) have been identified as novel mediators of intercellular communication. They work via delivering the sequestered cargo to cells in the close vicinity, as well as distant sites in the body, regulating pathophysiological processes. Cell death and inflammation are biologically crucial processes in both normal physiology and pathology. These processes are indistinguishably linked with their effectors modulating the other process. For instance, during an unresolvable infection, the upregulation of specific immune mediators leads to inflammation causing cell death and tissue damage. EVs have gained considerable interest as mediators of both cell death and inflammation during conditions, such as sepsis. This review summarizes the types of extracellular vesicles known to date and their roles in mediating immune responses leading to cell death and inflammation with specific focus on sepsis and lung inflammation.

Extracellular Vesicle-Based Therapy for COVID-19: Promises, Challenges and Future Prospects

The COVID-19 pandemic has become a serious concern and has negatively impacted public health and the economy. It primarily targets the lungs, causing acute respiratory distress syndrome (ARDS); however, it may also lead to multiple organ failure (MOF) and enhanced mortality rates. Hence, there is an urgent need to develop potential effective therapeutic strategies for COVID-19 patients. Extracellular vesicles (EVs) are released from various types of cells that participate in intercellular communication to maintain physiological and pathological processes. EVs derived from various cellular origins have revealed suppressive effects on the cytokine storm during systemic hyper-inflammatory states of severe COVID-19, leading to enhanced alveolar fluid clearance, promoted epithelial and endothelial recovery, and cell proliferation. Being the smallest subclass of EVs, exosomes offer striking characteristics such as cell targeting, being nano-carriers for drug delivery, high biocompatibility, safety, and low-immunogenicity, thus rendering them a potential cell-free therapeutic candidate against the pathogeneses of various diseases. Due to these properties, numerous studies and clinical trials have been performed to assess their safety and therapeutic efficacy against COVID-19. Hence, in this review, we have comprehensively described current updates on progress and challenges for EVs as a potential therapeutic agent for the management of COVID-19.

Challenges and opportunities in the study of extracellular vesicles: Global institutional context and national state of the art

In the last decade, the number of studies and publications on extracellular vesicles (EV) and exosomes has boomed. Colombia has displayed interest and progress in their study as shown in the increase of research project publications and products. However, this research field is still developing and has its own analytical challenges and technical limitations. For planning research projects and developing EV studies it is necessary to consider what is the state of the scientific field worldwide concerning EV nomenclature and classification, available techniques, resources, requirements and quality specifications, and the institutions that regulate the field. Answering this question will elicit EV studies that comply with international standards and respond to institutional demands and recommendations. However, the scientific information available is scattered and not all the aspects are considered in full. In this update, the available information is condensed and the official terms and currently defined nomenclature is presented, as well as the evolution of the field, the homogenization of the experimental parameters, the establishment of scientific authorities, institutions, and resources, and the recommendations generated worldwide for their development and research including their isolation, characterization, and functional studies. Finally, I analyzed the national context in a critical way, considering institutional strengths, common mistakes, and available analytical techniques and technologies.

Potential Therapeutic Effect of Micrornas in Extracellular Vesicles from Mesenchymal Stem Cells against SARS-CoV-2

Extracellular vesicles (EVs) are cell-released, nanometer-scaled, membrane-bound materials and contain diverse contents including proteins, small peptides, and nucleic acids. Once released, EVs can alter the microenvironment and regulate a myriad of cellular physiology components, including cell–cell communication, proliferation, differentiation, and immune responses against viral infection. Among the cargoes in the vesicles, small non-coding micro-RNAs (miRNAs) have received attention in that they can regulate the expression of a variety of human genes as well as external viral genes via binding to the complementary mRNAs. In this study, we tested the potential of EVs as therapeutic agents for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection. First, we found that the mesenchymal stem-cell-derived EVs (MSC-EVs) enabled the rescue of the cytopathic effect of SARS-CoV-2 virus and the suppression of proinflammatory responses in the infected cells by inhibiting the viral replication. We found that these anti-viral responses were mediated by 17 miRNAs matching the rarely mutated, conserved 3′-untranslated regions (UTR) of the viral genome. The top five miRNAs highly expressed in the MSC-EVs, miR-92a-3p, miR-26a-5p, miR-23a-3p, miR-103a-3p, and miR-181a-5p, were tested. They were bound to the complemented sequence which led to the recovery of the cytopathic effects. These findings suggest that the MSC-EVs are a potential candidate for multiple variants of anti-SARS-CoV-2.

Revealed pathophysiological mechanisms of crosslinking interaction of affected vital organs in COVID-19

SARS-CoV-2 is one of the main serious challenges of human societies, which emerged in December 2019 from China and quickly extends to all parts of the world. The virus was previously believed to only affect the lungs and respiratory system, but subsequent research has revealed that it affects a variety of organs. For this reason, this disease is known as a multiorgan disease. Current article aimed to highlight latest information and updates about molecular studies regarding pathogenesis of SARS-CoV-2 in kidney, liver, and cardiovascular and respiratory systems, as well as the mechanisms of interaction of these organs with each other to cause clinical manifestations in patients.

A Comprehensive Insight into the Role of Exosomes in Viral Infection: Dual Faces Bearing Different Functions

Extracellular vesicles (EVs) subtype, exosome is an extracellular nano-vesicle that sheds from cells’ surface and originates as intraluminal vesicles during endocytosis. Firstly, it was thought to be a way for the cell to get rid of unwanted materials as it loaded selectively with a variety of cellular molecules, including RNAs, proteins, and lipids. However, it has been found to play a crucial role in several biological processes such as immune modulation, cellular communication, and their role as vehicles to transport biologically active molecules. The latest discoveries have revealed that many viruses export their viral elements within cellular factors using exosomes. Hijacking the exosomal pathway by viruses influences downstream processes such as viral propagation and cellular immunity and modulates the cellular microenvironment. In this manuscript, we reviewed exosomes biogenesis and their role in the immune response to viral infection. In addition, we provided a summary of how some pathogenic viruses hijacked this normal physiological process. Viral components are harbored in exosomes and the role of these exosomes in viral infection is discussed. Understanding the nature of exosomes and their role in viral infections is fundamental for future development for them to be used as a vaccine or as a non-classical therapeutic strategy to control several viral infections.

Mesenchymal stem cells and their derived exosomes to combat Covid-19

Severe acute respiratory syndrome coronavirus 2 (SARS‐CoV‐2) is causing an ongoing pandemic of coronavirus disease 2019 (Covid‐19). Effective therapies are required for the treatment of patients with severe stages of the disease. Mesenchymal stem cells (MSCs) have been evaluated in numerous clinical trials, but present challenges, such as carcinogenic risk and special storage conditions, coupled with insufficient data about their mechanism of action. The majority of unique properties of MSCs are related to their paracrine activity and especially to their exosomes. The impact of MSCs‐derived exosomes (MSC‐Es) on complications of Covid‐19 has been investigated in several studies. MSC‐Es may improve some complications of Covid‐19 such as cytokine storm, acute respiratory distress syndrome (ARDS) and acute lung injury (ALI). Additionally, these exosomes can be evaluated as an applicable nano‐size carrier for antiviral therapeutic agents. Herein, we consider several potential applications of MSCs and their derived exosomes in the treatment of Covid‐19.

The Role of Exosomes in the Treatment, Prevention, Diagnosis, and Pathogenesis of COVID-19

The novel coronavirus disease 2019 (COVID-19) pandemic, caused by the severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2), continues to be a major health concern. In search for novel treatment strategies against COVID-19, exosomes have attracted the attention of scientists and pharmaceutical companies worldwide. Exosomes are small extracellular vesicles, secreted by all types of cells, and considered as key mediators of intercellular communication and stem-cell paracrine signaling. Herein, we reviewed the most recent literature about the role of exosomes as potential agents for treatment, prevention, diagnosis, and pathogenesis of COVID-19. Several studies and ongoing clinical trials have been investigating the anti-inflammatory, immunomodulatory, and reparative effects of exosomes derived from mesenchymal stem/stromal cells for COVID-19-related acute lung injury. Other studies reported that exosomes play a key role in convalescent plasma therapy for COVID-19, and that they could be of use for the treatment of COVID-19 Kawasaki's-like multisystem inflammatory syndrome and as drug delivery nanocarriers for antiviral therapy. Harnessing some advantageous aspects of exosome biology, such as their endogenous origin, capability of crossing biological barriers, high stability in circulation, and low toxicity and immunogenicity, several companies have been testing exosome-based vaccines against SARS-CoV-2. As they carry cargos that mimic the status of parent cells, exosomes can be isolated from a variety of sources, including plasma, and employed as biomarkers of COVID-19. Lastly, there is growing evidence supporting the role of exosomes in COVID-19 infection, spread, reactivation, and reinfection. The lessons learned using exosomes for COVID-19 will help determine their efficacy and applicability in other clinical conditions.

Cell therapy strategies for COVID-19: Current approaches and potential applications

Coronavirus disease 2019 (COVID-19) continues to burden society worldwide. Despite most patients having a mild course, severe presentations have limited treatment options. COVID-19 manifestations extend beyond the lungs and may affect the cardiovascular, nervous, and other organ systems. Current treatments are nonspecific and do not address potential long-term consequences such as pulmonary fibrosis, demyelination, and ischemic organ damage. Cell therapies offer great potential in treating severe COVID-19 presentations due to their customizability and regenerative function. This review summarizes COVID-19 pathogenesis, respective areas where cell therapies have potential, and the ongoing 89 cell therapy trials in COVID-19 as of 1 January 2021.

Diverse Effects of Exosomes on COVID-19: A Perspective of Progress From Transmission to Therapeutic Developments

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a new strain of coronavirus and the causative agent of the current global pandemic of coronavirus disease 2019 (COVID-19). There are currently no FDA-approved antiviral drugs for COVID-19 and there is an urgent need to develop treatment strategies that can effectively suppress SARS-CoV-2 infection. Numerous approaches have been researched so far, with one of them being the emerging exosome-based therapies. Exosomes are nano-sized, lipid bilayer-enclosed structures, share structural similarities with viruses secreted from all types of cells, including those lining the respiratory tract. Importantly, the interplay between exosomes and viruses could be potentially exploited for antiviral drug and vaccine development. Exosomes are produced by virus-infected cells and play crucial roles in mediating communication between infected and uninfected cells. SARS-CoV-2 modulates the production and composition of exosomes, and can exploit exosome formation, secretion, and release pathways to promote infection, transmission, and intercellular spread. Exosomes have been exploited for therapeutic benefits in patients afflicted with various diseases including COVID-19. Furthermore, the administration of exosomes loaded with immunomodulatory cargo in combination with antiviral drugs represents a novel intervention for the treatment of diseases such as COVID-19. In particular, exosomes derived from mesenchymal stem cells (MSCs) are used as cell-free therapeutic agents. Mesenchymal stem cell derived exosomes reduces the cytokine storm and reverse the inhibition of host anti-viral defenses associated with COVID-19 and also enhances mitochondrial function repair lung injuries. We discuss the role of exosomes in relation to transmission, infection, diagnosis, treatment, therapeutics, drug delivery, and vaccines, and present some future perspectives regarding their use for combating COVID-19.

Identification of Tomato Infecting Viruses That Co-Isolate with Nanovesicles Using a Combined Proteomics and Electron-Microscopic Approach

Plant-derived nanovesicles (NVs) have attracted interest due to their anti-inflammatory, anticancer and antioxidative properties and their efficient uptake by human intestinal epithelial cells. Previously we showed that tomato (Solanum lycopersicum L.) fruit is one of the interesting plant resources from which NVs can be obtained at a high yield. In the course of the isolation of NVs from different batches of tomatoes, using the established differential ultracentrifugation or size-exclusion chromatography methods, we occasionally observed the co-isolation of viral particles. Density gradient ultracentrifugation (gUC), using sucrose or iodixanol gradient materials, turned out to be efficient in the separation of NVs from the viral particles. We applied cryogenic transmission electron microscopy (cryo-TEM), scanning electron microscopy (SEM) for the morphological assessment and LC-MS/MS-based proteomics for the protein identification of the gradient fractions. Cryo-TEM showed that a low-density gUC fraction was enriched in membrane-enclosed NVs, while the high-density fractions were rich in rod-shaped objects. Mass spectrometry-based proteomic analysis identified capsid proteins of tomato brown rugose fruit virus, tomato mosaic virus and tomato mottle mosaic virus. In another batch of tomatoes, we isolated tomato spotted wilt virus, potato virus Y and southern tomato virus in the vesicle sample. Our results show the frequent co-isolation of plant viruses with NVs and the utility of the combination of cryo-TEM, SEM and proteomics in the detection of possible viral contamination.

Mesenchymal Stem Cell-Based Therapy as an Alternative to the Treatment of Acute Respiratory Distress Syndrome: Current Evidence and Future Perspectives

Acute respiratory distress syndrome (ARDS) represents a current challenge for medicine due to its incidence, morbidity and mortality and, also, the absence of an optimal treatment. The COVID-19 outbreak only increased the urgent demand for an affordable, safe and effective treatment for this process. Early clinical trials suggest the therapeutic usefulness of mesenchymal stem cells (MSCs) in acute lung injury (ALI) and ARDS. MSC-based therapies show antimicrobial, anti-inflammatory, regenerative, angiogenic, antifibrotic, anti-oxidative stress and anti-apoptotic actions, which can thwart the physiopathological mechanisms engaged in ARDS. In addition, MSC secretome and their derived products, especially exosomes, may reproduce the therapeutic effects of MSC in lung injury. This last strategy of treatment could avoid several safety issues potentially associated with the transplantation of living and proliferative cell populations and may be formulated in different forms. However, the following diverse limitations must be addressed: (i) selection of the optimal MSC, bearing in mind both the heterogeneity among donors and across different histological origins, (ii) massive obtention of these biological products through genetic manipulations of the most appropriate MSC, (iii) bioreactors that allow their growth in 3D, (iv) ideal culture conditions and (v) adequate functional testing of these obtaining biological products before their clinical application.

Exosome-Based Vaccines: History, Current State, and Clinical Trials

Extracellular vesicles (EVs) are released by most cell types as part of an intracellular communication system in crucial processes such as inflammation, cell proliferation, and immune response. However, EVs have also been implicated in the pathogenesis of several diseases, such as cancer and numerous infectious diseases. An important feature of EVs is their ability to deliver a wide range of molecules to nearby targets or over long distances, which allows the mediation of different biological functions. This delivery mechanism can be utilized for the development of therapeutic strategies, such as vaccination. Here, we have highlighted several studies from a historical perspective, with respect to current investigations on EV-based vaccines. For example, vaccines based on exosomes derived from dendritic cells proved to be simpler in terms of management and cost-effectiveness than dendritic cell vaccines. Recent evidence suggests that EVs derived from cancer cells can be leveraged for therapeutics to induce strong anti-tumor immune responses. Moreover, EV-based vaccines have shown exciting and promising results against different types of infectious diseases. We have also summarized the results obtained from completed clinical trials conducted on the usage of exosome-based vaccines in the treatment of cancer, and more recently, coronavirus disease.

A Role for Extracellular Vesicles in SARS-CoV-2 Therapeutics and Prevention

Extracellular vesicles (EVs) are the common designation for ectosomes, microparticles and microvesicles serving dominant roles in intercellular communication. Both viable and dying cells release EVs to the extracellular environment for transfer of cell, immune and infectious materials. Defined morphologically as lipid bi-layered structures EVs show molecular, biochemical, distribution, and entry mechanisms similar to viruses within cells and tissues. In recent years their functional capacities have been harnessed to deliver biomolecules and drugs and immunological agents to specific cells and organs of interest or disease. Interest in EVs as putative vaccines or drug delivery vehicles are substantial. The vesicles have properties of receptors nanoassembly on their surface. EVs can interact with specific immunocytes that include antigen presenting cells (dendritic cells and other mononuclear phagocytes) to elicit immune responses or affect tissue and cellular homeostasis or disease. Due to potential advantages like biocompatibility, biodegradation and efficient immune activation, EVs have gained attraction for the development of treatment or a vaccine system against the severe acute respiratory syndrome coronavirus 2 (SARS CoV-2) infection. In this review efforts to use EVs to contain SARS CoV-2 and affect the current viral pandemic are discussed. An emphasis is made on mesenchymal stem cell derived EVs' as a vaccine candidate delivery system.

Different kinds of stem cells in the development of SARS-CoV-2 treatments

On February 11, 2020, the World Health Organization officially announced the coronavirus disease 2019 (COVID-19) caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), as an emerging recent pandemic illness, which currently has approximately taken the life of two million persons in more than 200 countries. Medical, clinical, and scientific efforts have focused on searching for new prevention and treatment strategies. Regenerative medicine and tissue engineering focused on using stem cells (SCs) have become a promising tool, and the regenerative and immunoregulatory capabilities of mesenchymal SCs (MSCs) and their exosomes have been demonstrated. Moreover, it has been essential to establishing models to reproduce the viral life cycle and mimic the pathology of COVID-19 to understand the virus's behavior. The fields of pluripotent SCs (PSCs), induced PSCs (iPSCs), and artificial iPSCs have been used for this purpose in the development of infection models or organoids. Nevertheless, some inconveniences have been declared in SC use; for example, it has been reported that SARS-CoV-2 enters human cells through the angiotensin-converting enzyme 2 receptor, which is highly expressed in MSCs, so it is important to continue investigating the employment of SCs in COVID-19, taking into consideration their advantages and disadvantages. In this review, we expose the use of different kinds of SCs and their derivatives for studying the SARS-CoV-2 behavior and develop treatments to counter COVID-19.

Endothelial Extracellular Vesicles: From Keepers of Health to Messengers of Disease

Endothelium has a rich vesicular network that allows the exchange of macromolecules between blood and parenchymal cells. This feature of endothelial cells, along with their polarized secretory machinery, makes them the second major contributor, after platelets, to the particulate secretome in circulation. Extracellular vesicles (EVs) produced by the endothelial cells mirror the remarkable molecular heterogeneity of their parent cells. Cargo molecules carried by EVs were shown to contribute to the physiological functions of endothelium and may support the plasticity and adaptation of endothelial cells in a paracrine manner. Endothelium-derived vesicles can also contribute to the pathogenesis of cardiovascular disease or can serve as prognostic or diagnostic biomarkers. Finally, endothelium-derived EVs can be used as therapeutic tools to target endothelium for drug delivery or target stromal cells via the endothelial cells. In this review we revisit the recent evidence on the heterogeneity and plasticity of endothelial cells and their EVs. We discuss the role of endothelial EVs in the maintenance of vascular homeostasis along with their contributions to endothelial adaptation and dysfunction. Finally, we evaluate the potential of endothelial EVs as disease biomarkers and their leverage as therapeutic tools.

Mechanistic and Therapeutic Implications of Extracellular Vesicles as a Potential Link Between Covid-19 and Cardiovascular Disease Manifestations

Extracellular vesicles (EVs), which are cell released double layered membrane particles, have been found in every circulating body fluid, and provide a tool for conveying diverse information between cells, influencing both physiological and pathological conditions. Viruses can hijack the EVs secretory pathway to exit infected cells and use EVs endocytic routes to enter uninfected cells, suggesting that EVs and viruses can share common cell entry and biogenesis mechanisms. SARS-CoV-2 is responsible of the coronavirus disease 2019 (Covid-19), which may be accompanied by severe multi-organ manifestations. EVs may contribute to virus spreading via transfer of virus docking receptors such as CD9 and ACE2. Covid-19 is known to affect the renin angiotensin system (RAS), and could promote secretion of harmful EVs. In this scenario EVs might be linked to cardiovascular manifestations of the Covid-19 disease through unbalance in RAS. In contrast EVs derived from mesenchymal stem cells or cardiosphere derived cells, may promote cardiovascular function due to their beneficial effect on angiogenesis, fibrosis, contractility and immuno-modulation. In this article we assessed the potential impact of EVs in cardiovascular manifestations of Covid-19 and highlight potential strategies to control the extracellular signaling for future therapies.

Therapeutic Potential of Mesenchymal Stem Cells and Their Products in Lung Diseases-Intravenous Administration versus Inhalation

The number of publications studying the therapeutic use of stem cells has steadily increased since 2000. Compared to other applications, there has been little interest in the evaluation of mesenchymal stem cells (MSCs) and MSC-derived products (mostly extracellular vesicles) for the treatment of respiratory diseases. Due to the lack of efficient treatments for acute respiratory distress syndrome caused by infections with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), the action of MSCs has also been studied. This review describes mode of action and use of MSCs and MSC-derived products in the treatment of lung diseases including the respective advantages and limitations of the products. Further, issues related to standardized production are addressed. Administration by inhalation of MSCs, compared to intravenous injection, could decrease cell damage by shear stress, eliminate the barrier to reach target cells in the alveoli, prevent thrombus formation in the pulmonary vasculature and retention in filter for extracorporeal membrane oxygenation. There is more feasible to deliver extracellular vesicles than MSCs with inhalers, offering the advantage of non-invasive and repeated administration by the patient. Major obstacles for comparison of results are heterogeneity of the products, differences in the treatment protocols and small study cohorts.