Transfer of microRNAs by embryonic stem cell microvesicles

Exosome-mediated communication between T cells and dendritic cells: Implications for therapeutic strategies

Cell communication is crucial for coordinating physiological functions in multicellular organisms, with exosomes playing a significant role. Exosomes mediate intercellular communication by transporting proteins, lipids, and nucleic acids between cells. These small, membrane-bound vesicles, derived from the endosomal pathway, are integral to various biological processes, including signal transmission and cellular behavior modulation. Recent advances highlight the potential of exosomes, especially dendritic cell-derived exosomes (DEXs), for diagnostic and therapeutic applications, particularly in cancer immunotherapy. DEXs are distinguished by their ability to present antigens and stimulate immune responses more effectively than exosomes from other cell types. They carry a cargo rich in immunostimulatory molecules and MHC-peptide complexes, which facilitate robust T-cell activation and enhance tumor-specific immune responses. The unique properties of DEXs, such as their ability to cross biological barriers and resist tumor-induced immunosuppression, position them as promising candidates for therapeutic applications. Here, I review the reports on the bidirectional interaction between dendritic cells and T cells through exosomes and their role in medicine.

Blood-based biomarkers in pancreatic ductal adenocarcinoma: developments over the last decade and what holds for the future- a review

Pancreatic Ductal Adenocarcinoma (PDAC) accounts for a significant burden of global cancer deaths worldwide. The dismal outcomes associated with PDAC can be overcome by detecting the disease early and developing tools that predict response to treatment, allowing the selection of the most optimal treatment. Over the last couple of years, significant progress has been made in the development of novel biomarkers that aid in diagnosis, prognosis, treatment selection, and monitoring response. Blood-based biomarkers offer an alternative to tissue-based diagnosis and offer immense potential in managing PDAC. In this review, we have discussed the advances in blood-based biomarkers in PDAC, such as DNA (mutations and methylations), RNA, protein biomarkers and circulating tumor cells (CTC) over the last decade and also elucidated all aspects of practical implementation of these biomarkers in clinical practice. We have also discussed implementing multiomics utilizing more than one biomarker and targeted therapies that have been developed using these biomarkers.

Urinary and Plasma miRNAs in the Early Detection of Acute Kidney Injury and Their Possible Role as Therapeutic Targets

Acute Kidney Injury (AKI) is a severe clinical condition featured by a rapid decrease in kidney function in a short period of time. AKI, which is often secondary to sepsis, ischemia-reperfusion and drug toxicity, is associated to high morbidity and mortality. Moreover, it contributes to the development of chronic kidney disease (CKD), due to maladaptive or incomplete repair mechanisms, resulting in renal fibrosis. Small non-coding RNA has recently emerged as a novel biomarker for the early detection and treatment of AKI. In particular, microRNAs (miRNAs) are non-coding RNA molecules of 21-25 nucleotides regulating the expression of protein-coding genes through sequence-specific recognition. Due to their high stability in biological fluids, such as urine and plasma, they can be reliably analyzed and quantified, and for this reason they can be considered potential diagnostic and therapeutic biomarkers. Specifically, miRNAs have been demonstrated to predict AKI before the increase in creatinine levels, thus improving the management of this syndrome. In this review, we provide a comprehensive overview of the role of urinary and plasma miRNAs in the early detection and treatment of AKI.

Circulating microRNAs in Body Fluid: "Fingerprint" RNA Snippets Deeply Impact Reproductive Biology

Circulating miRNAs (C-miRNAs) occuring in a cell-free form within body fluids and other extracellular environments have garnered attention in recent times. They offer deeper insight into various physiological and pathological processes which include reproductive health. This review delves into their diagnostic potential across a spectrum of reproductive disorders, including conditions affecting ovarian function, male infertility and post pregnancy issues. Through analysis of C-miRNA profiles in bodily fluids, researchers uncover crucial markers indicative of reproductive challenges. Dysregulated C-miRNAs emerge as important players in the progression of several reproductive disorders which is the main focus of this review. Advancements in technology, facilitate precise detection and quantification of C-miRNAs, paving the way for innovative diagnostic approaches. Challenges in studying C-miRNAs, such as their low abundance and variability in expression levels, underscore the need for standardized protocols and rigorous validation methods. Despite these challenges, ongoing research endeavors aim to unravel the complex regulatory roles of C-miRNAs in reproductive biology, with potential implications for clinical practice and therapeutic interventions.

Nano-Delivery Revolution: Harnessing Mesenchymal Stem Cell-Derived Exosomes' Potential for Wound Healing

Stem cell transplantation has proven effective in treating acute and chronic wounds, but its limitations, such as low cellular viability and the need for specialized transportation, highlight the necessity for alternative approaches. This review explores the potential of engineered exosomes, containing identified miRNAs/peptides, as a more stable and efficient cell-free therapy for regenerative medicine, particularly in wound healing. The discussion emphasizes the benefits of exosomes, including their stability, reduced damage, and consistent biological activity, paving the way for innovative applications like lyophilized exosomes, mist spray delivery, and exosome-based scaffolds. The exploration of cell-free therapy in this review holds promising implications for advancing wound-healing strategies.

Blood-based microRNAs as the potential biomarkers for Alzheimer's disease: evidence from a systematic review

Alzheimer's disease (AD) is a neurodegenerative disorder that progresses over time and is identified by the development of neurofibrillary tangles and amyloid deposits in the brain. Mounting evidence has revealed that microRNAs (miRNAs) are significantly involved in AD progression, and may be used as promising biomarkers for diagnosis and prognosis. Nevertheless, the existing body of data regarding dysregulated circulating miRNAs in AD and their therapeutic applications are characterized by a lack of consistency. A comprehensive search was performed across various databases (PubMed, EMBASE, Web of Science, Scopus, Google Scholar, Cochrane, and ProQuest), starting from its inception and ending in January 2023. The criteria for inclusion consisted of original research studies written in English, which utilized Real-Time PCR to analyze miRNA expression in the blood, serum, or plasma of AD patients and healthy controls. The extracted data included the miRNA(s) investigated, dysregulation status, study type, human sample(s), and major findings. The search produced 608 records, which after careful examination, resulted in 48 suitable articles for data extraction. The research revealed a wide range of sample types used, with whole blood (39.59%) and serum (27.09%, including serum-exosome at 4.17%) emerging as the most prominent. The compiled dataset featured 4001 AD patients and 3886 healthy controls, revealing intricate regulatory patterns among 83 up-regulated (35.78%), 66 down-regulated (28.44%), and 83 not significantly altered (35.78%) miRNAs. Our results demonstrated that specific circulating miRNAs are consistently dysregulated in AD and could serve as non-intrusive biomarkers for the identification, prognosis, and prediction of cognitive decline. Further large-scale prospective studies are required to validate their clinical applications.

Modulation of naïve mesenchymal stromal cells by extracellular vesicles derived from insulin-producing cells: an in vitro study

This study was to determine whether extracellular vesicles (EVs) derived from insulin-producing cells (IPCs) can modulate naïve mesenchymal stromal cells (MSCs) to become insulin-secreting. MSCs were isolated from human adipose tissue. The cells were then differentiated to generate IPCs by achemical-based induction protocol. EVs were retrieved from the conditioned media of undifferentiated (naïve) MSCs (uneducated EVs) and from that of MSC-derived IPCs (educated EVs) by sequential ultracentrifugation. The obtained EVs were co-cultured with naïve MSCs.The cocultured cells were evaluated by immunofluorescence, flow cytometry, C-peptide nanogold silver-enhanced immunostaining, relative gene expression and their response to a glucose challenge.Immunostaining for naïve MSCs cocultured with educated EVs was positive for insulin, C-peptide, and GAD65. By flow cytometry, the median percentages of insulin-andC-peptide-positive cells were 16.1% and 14.2% respectively. C-peptide nanogoldimmunostaining providedevidence for the intrinsic synthesis of C-peptide. These cells released increasing amounts of insulin and C-peptide in response to increasing glucose concentrations. Gene expression of relevant pancreatic endocrine genes, except for insulin, was modest. In contrast, the results of naïve MSCs co-cultured with uneducated exosomes were negative for insulin, C-peptide, and GAD65. These findings suggest that this approach may overcome the limitations of cell therapy.

Fluorescent, phosphorescent, magnetic resonance contrast and radioactive tracer labelling of extracellular vesicles

This review focusses on the significance of fluorescent, phosphorescent labelling and tracking of extracellular vesicles (EVs) for unravelling their biology, pathophysiology, and potential diagnostic and therapeutic uses. Various labeling strategies, such as lipid membrane, surface protein, luminal, nucleic acid, radionuclide, quantum dot labels, and metal complex-based stains, are evaluated for visualizing and characterizing EVs. Direct labelling with fluorescent lipophilic dyes is simple but generally lacks specificity, while surface protein labelling offers selectivity but may affect EV-cell interactions. Luminal and nucleic acid labelling strategies have their own advantages and challenges. Each labelling approach has strengths and weaknesses, which require a suitable probe and technique based on research goals, but new tetranuclear polypyridylruthenium(II) complexes as phosphorescent probes have strong phosphorescence, selective staining, and stability. Future research should prioritize the design of novel fluorescent probes and labelling platforms that can significantly enhance the efficiency, accuracy, and specificity of EV labeling, while preserving their composition and functionality. It is crucial to reduce false positive signals and explore the potential of multimodal imaging techniques to gain comprehensive insights into EVs.

Neutrophil microRNAs

Neutrophils are considered 'first-line defence' cells as they can be rapidly recruited to the site of the immune response. As key components of non-specific immune mechanisms, neutrophils use phagocytosis, degranulation, and formation of neutrophil extracellular traps (NETs) to fight pathogens. Recently, immunoregulatory abilities of neutrophils associated with the secretion of several mediators, including cytokines and extracellular vesicles (EVs) containing, among other components, microRNAs (miRNAs), have also been reported. EVs are small structures released by cells into the extracellular space and are present in all body fluids. Microvesicles show the composition and status of the releasing cell, its physiological state, and pathological changes. Currently, EVs have gained immense scientific interest as they act as transporters of epigenetic information in intercellular communication. This review summarises findings from recent scientific reports that have evaluated the utility of miRNA molecules as biomarkers for effective diagnostics or even as start-points for new therapeutic strategies in neutrophil-mediated immune reactions. In addition, this review describes the current state of knowledge on miRNA molecules, which are endogenous regulators of gene expression besides being involved in the regulation of the immune response.

Human PSC-derived cardiac cells and their products: therapies for cardiac repair

Despite the dramatic improvements in the management of patients with chronic heart failure which have occurred over the last decades, some of them still exhaust conventional drug-based therapies without being eligible for more aggressive options like heart transplantation or implantation of a left ventricular assist device. Cell therapy has thus emerged as a possible means of filling this niche. Multiple cell types have now been tested both in the laboratory but also in the clinics and it is fair to acknowledge that none of the clinical trials have yet conclusively proven the efficacy of cell-based approaches. These clinical studies, however, have entailed the use of cells from various sources but of non-cardiac lineage origins. Although this might not be the main reason for their failures, the discovery of pluripotent stem cells capable of generating cardiomyocytes now raises the hope that such cardiac-committed cells could be therapeutically more effective. In this review, we will first describe where we currently are with regard to the clinical trials using PSC-differentiated cells and discuss the main issues which remain to be addressed. In parallel, because the capacity of cells to stably engraft in the recipient heart has increasingly been questioned, it has been hypothesized that a major mechanism of action could be the cell-triggered release of biomolecules that foster host-associated reparative pathways. Thus, in the second part of this review, we will discuss the rationale, clinically relevant advantages and pitfalls associated with the use of these PSC "products".

Extracellular vesicles throughout development: A potential roadmap for emerging glioblastoma therapies

Extracellular vesicles (EVs) are membrane-delimited vesicular bodies carrying different molecules, classified according to their size, density, cargo, and origin. Research on this topic has been actively growing through the years, as EVs are associated with critical pathological processes such as neurodegenerative diseases and cancer. Despite that, studies exploring the physiological functions of EVs are sparse, with particular emphasis on their role in organismal development, initial cell differentiation, and morphogenesis. In this review, we explore the topic of EVs from a developmental perspective, discussing their role in the earliest cell-fate decisions and neural tissue morphogenesis. We focus on the function of EVs through development to highlight possible conserved or novel processes that can impact disease progression. Specifically, we take advantage of what was learned about their role in development so far to discuss EVs impact on glioblastoma, a particular brain tumor of stem-cell origin and poor prognosis, and how their function can be hijacked to improve current therapies.

Extracellular vesicles in the retina - putative roles in physiology and disease

The retina encompasses a network of neurons, glia and epithelial and vascular endothelia cells, all coordinating visual function. Traditionally, molecular information exchange in this tissue was thought to be orchestrated by synapses and gap junctions. Recent findings have revealed that many cell types are able to package and share molecular information via extracellular vesicles (EVs) and the technological advancements in visualisation and tracking of these delicate nanostructures has shown that the role of EVs in cell communication is pleiotropic. EVs are released under physiological conditions by many cells but they are also released during various disease stages, potentially reflecting the health status of the cells in their cargo. Little is known about the physiological role of EV release in the retina. However, administration of exogenous EVs in vivo after injury suggest a neurotrophic role, whilst photoreceptor transplantation in early stages of retina degeneration, EVs may facilitate interactions between photoreceptors and Müller glia cells. In this review, we consider some of the proposed roles for EVs in retinal physiology and discuss current evidence regarding their potential impact on ocular therapies via gene or cell replacement strategies and direct intraocular administration in the diseased eye.

miR-133a-A Potential Target for Improving Cardiac Mitochondrial Health and Regeneration After Injury

ABSTRACT

The various roles of muscle secretory factors and myokines have been well studied, but in recent decades, the role of myocyte-specific microRNAs (myomiRs) has gained momentum. These myomiRs are known to play regulatory roles in muscle health in general, both skeletal muscle and cardiac muscle. In this review, we have focused on the significance of a myomiR termed miR-133a in cardiovascular health. The available literature supports the claim that miR-133a could be helpful in the healing process of muscle tissue after injury. The protective function could be due to its regulatory effect on muscle or stem cell mitochondrial function. In this review, we have shed light on the protective mechanisms offered by miR-133a. Most of the beneficial effects are due to the presence of miR-133a in circulation or tissue-specific expression. We have also reviewed the potential mechanisms by which miR-133a could interact with cell surface receptors and also transcriptional mechanisms by which they offer cardioprotection and regeneration. Understanding these mechanisms will help in finding an ideal strategy to repair cardiac tissue after injury.

Scalable Production of Extracellular Vesicles and Its Therapeutic Values: A Review

Extracellular vesicles (EVs) are minute vesicles with lipid bilayer membranes. EVs are secreted by cells for intercellular communication. Recently, EVs have received much attention, as they are rich in biological components such as nucleic acids, lipids, and proteins that play essential roles in tissue regeneration and disease modification. In addition, EVs can be developed as vaccines against cancer and infectious diseases, as the vesicle membrane has an abundance of antigenic determinants and virulent factors. EVs for therapeutic applications are typically collected from conditioned media of cultured cells. However, the number of EVs secreted by the cells is limited. Thus, it is critical to devise new strategies for the large-scale production of EVs. Here, we discussed the strategies utilized by researchers for the scalable production of EVs. Techniques such as bioreactors, mechanical stimulation, electrical stimulation, thermal stimulation, magnetic field stimulation, topographic clue, hypoxia, serum deprivation, pH modification, exposure to small molecules, exposure to nanoparticles, increasing the intracellular calcium concentration, and genetic modification have been used to improve the secretion of EVs by cultured cells. In addition, nitrogen cavitation, porous membrane extrusion, and sonication have been utilized to prepare EV-mimetic nanovesicles that share many characteristics with naturally secreted EVs. Apart from inducing EV production, these upscaling interventions have also been reported to modify the EVs' cargo and thus their functionality and therapeutic potential. In summary, it is imperative to identify a reliable upscaling technique that can produce large quantities of EVs consistently. Ideally, the produced EVs should also possess cargo with improved therapeutic potential.

Exosomes as Emerging Drug Delivery and Diagnostic Modality for Breast Cancer: Recent Advances in Isolation and Application

Breast cancer (BC) is the most common type of malignancy which covers almost one-fourth of all the cancers diagnosed in women. Conventionally, chemo-, hormonal-, immune-, surgery, and radiotherapy are the clinically available therapies for BC. However, toxicity and other related adverse effects are still the major challenges. A variety of nano platforms have been reported to overcome these limitations, among them, exosomes provide a versatile platform not only for the diagnosis but also as a delivery vehicle for drugs. Exosomes are biological nanovesicles made up of a lipidic bilayer and known for cell-to-cell communication. Exosomes have been reported to be present in almost all bodily fluids, viz., blood, milk, urine, saliva, pancreatic juice, bile, peritoneal, and cerebrospinal fluid. Such characteristics of exosomes have attracted immense interest in cancer diagnosis and therapy. They can deliver bioactive moieties such as protein, lipids, hydrophilic as well as hydrophobic drugs, various RNAs to both distant and nearby recipient cells as well as have specific biological markers. By considering the growing interest of the scientific community in this field, we comprehensively compiled the information about the biogenesis of exosomes, various isolation methods, the drug loading techniques, and their diverse applications in breast cancer diagnosis and therapy along with ongoing clinical trials which will assist future scientific endeavors in a more organized direction.

The Role of Mesenchymal Stem Cells in the Induction of Cancer-Stem Cell Phenotype

Cancer stem cells (CSCs) modify and form their microenvironment by recruiting and activating specific cell types such as mesenchymal stem cells (MSCs). Tumor-infiltrating MSCs help to establish a suitable tumor microenvironment for the restoration of CSCs and tumor progression. In addition, crosstalk between cancer cells and MSCs in the microenvironment induces a CSC phenotype in cancer cells. Many mechanisms are involved in crosstalk between CSCs/cancer cells and MSCs including cell-cell interaction, secretion of exosomes, and paracrine secretion of several molecules including inflammatory mediators, cytokines, and growth factors. Since this crosstalk may contribute to drug resistance, metastasis, and tumor growth, it is suggested that blockade of the crosstalk between MSCs and CSCs/cancer cells can provide a new avenue to improving the cancer therapeutic tools. In this review, we will discuss the role of MSCs in the induction of cancer stem cell phenotype and the restoration of CSCs. We also discuss targeting the crosstalk between MSCs and CSCs/cancer cells as a therapeutic strategy.

Extracellular Vesicles—New Players in Cell-To-Cell Communication in Gestational Diabetes Mellitus

Research in extracellular vesicles (EVs) has contributed to a better understanding of physiological and pathophysiological conditions. Biologically active cargo, such as miRNAs and proteins, is critical in many different biological processes. In this context, pregnancy is one of the most complex physiological states, which needs a highly regulated system to ensure the correct nourishment and development of the baby. However, pre-existent maternal conditions and habits can modify the EV-cargo and dysregulate the system leading to pregnancy complications, with gestational diabetes mellitus (GDM) being one of the most reported and influential. Calcification and aging of muscle cells, protein modification in vascular control or variations in the levels of specific miRNAs are some of the changes observed or led by EV populations as adaptation to GDM. Interestingly, insulin sensitivity and glucose tolerance changes are not fully understood to date. Nevertheless, the increasing evidence generated has opened new possibilities in the biomarker discovery field but also in the understanding of cellular mechanisms modified and involved in GDM. This brief review aims to discuss some of the findings in GDM and models used for that purpose and their potential roles in the metabolic alterations during pregnancy, with a focus on insulin sensitivity and glucose tolerance.

Stimulatory Effects of Extracellular Vesicles Derived from Leuconostoc holzapfelii That Exists in Human Scalp on Hair Growth in Human Follicle Dermal Papilla Cells

Human hair follicle dermal papilla cells (HFDPCs) located in hair follicles (HFs) play a pivotal role in hair follicle morphogenesis, hair cycling, and hair growth. Over the past few decades, probiotic bacteria (PB) have been reported to have beneficial effects such as improved skin health, anti-obesity, and immuno-modulation for conditions including atopic dermatitis and inflammatory bowel disease (IBD). PB can secrete 50~150 nm sized extracellular vesicles (EVs) containing microbial DNA, miRNA, proteins, lipids, and cell wall components. These EVs can regulate communication between bacteria or between bacteria and their host. Although numerous biological effects of PB-EVs have been reported, the physiological roles of Leuconostoc holzapfelii (hs-Lh), which is isolated from human scalp tissue, and the extracellular vesicles derived from them (hs-LhEVs) are largely unknown. Herein, we investigated the effects of hs-LhEVs on hair growth in HFDPCs. We show that hs-LhEVs increase cell proliferation, migration, and regulate the cell cycle. Furthermore, hs-LhEVs were found to modulate the mRNA expression of hair-growth-related genes in vitro. These data demonstrate that hs-LhEVs can reduce apoptosis by modulating the cell cycle and promote hair growth by regulation via the Wnt/β-catenin signal transduction pathway.

Secretome of Stem Cells: Roles of Extracellular Vesicles in Diseases, Stemness, Differentiation, and Reprogramming

Increasing evidence suggests that stem cells or stem cell-derived cells may contribute to tissue repair, not only by replacing lost tissue but also by delivering complex sets of secretory molecules, called secretomes, into host injured tissues. In recent years, extracellular vesicles (EVs) have gained much attention for their diverse and important roles in a wide range of pathophysiological processes. EVs are released from most types of cells and mediates cell-cell communication by activating receptors on target cells or by being taken up by recipient cells. EVs, including microvesicles and exosomes, encapsulate and carry proteins, nucleic acids, and lipids in the lumen and on the cell surface. Thus, EV-mediated intercellular communication has been extensively studied across various biological processes. While a number of investigations has been conducted in different tissues and body fluids, the field lacks a systematic review on stem cell-derived EVs, especially regarding their roles in stemness and differentiation. Here, we provide an overview of the pathophysiological roles of EVs and summarize recent findings focusing on EVs released from various types of stem cells. We also highlight emerging evidence for the potential implication of EVs in self-renewal, differentiation, and reprograming and discuss the benefits and limitations in translational approaches.

Exosomal microRNAs as Potential Biomarkers and Therapeutic Agents for Acute Ischemic Stroke: New Expectations

The morbidity and mortality rates of ischemic stroke (IS) are very high, and IS constitutes one of the main causes of disability and death worldwide. The pathogenesis of ischemic stroke includes excitotoxicity, calcium overload, oxygen radical injury, inflammatory reactions, necrosis/apoptosis, destruction of the blood-brain barrier (BBB), and other pathologic processes. Recent studies have shown that exosomes are critical to the pathogenesis, diagnosis, and treatment of cerebral infarctions resulting from ischemic stroke; and there is growing interest in the role of exosomes and exosomal miRNAs in the diagnosis and treatment of IS. Exosomes from central nervous system cells can be found in cerebrospinal fluid and peripheral bodily fluids, and exosomal contents have been reported to change with disease occurrence. Exosomes are small membranous extracellular vesicles (EVs), 30–150 nm in diameter, that are released from the cell membrane into the depressions that arise from the membranes of multivesicular bodies. Exosomes carry lipids, proteins, mRNAs, and microRNAs (miRNAs) and transport information to target cells. This exosomal transfer of functional mRNAs/miRNAs and proteins ultimately affects transcription and translation within recipient cells. Exosomes are EVs with a double-membrane structure that protects them from ribonucleases in the blood, allowing exosomal miRNAs to be more stable and to avoid degradation. New evidence shows that exosomes derived from neural cells, endothelial cells, and various stem cells create a fertile environment that supports the proliferation and growth of neural cells and endothelial cells, inhibits apoptosis and inflammatory responses, and promotes angiogenesis. In the present review, we discuss how circulating exosomes—and exosomal miRNAs in particular—may provide novel strategies for the early diagnosis and treatment of ischemic stroke via their potential as non-invasive biomarkers and drug carriers.

The role and therapeutic potential of exosomes in ischemic stroke

Ischemic stroke is a disease caused by insufficient blood and oxygen supply to the brain, which is mainly due to intracranial arterial stenosis and middle cerebral artery occlusion. Exosomes play an important role in cerebral ischemia. Nucleic acid substances such as miRNA, circRNA, lncRNA in exosomes can play communication roles and improve cerebral ischemia by regulating the development and regeneration of the nervous system, remodeling of blood vessels and inhibiting neuroinflammation. Furthermore, exosomes modulate stroke through various mechanisms, including improving neural communication, promoting the development of neuronal cells and myelin synapses, neurovascular unit remodeling and maintaining homeostasis of the nervous system. At the same time, exosomes are also a good carrier of bioactive substances, which can be modified and targeted to the lesion site. Here, we review the roles of exosomes in cerebral ischemia, and discuss the possible mechanisms and potentials of modification of exosomes for targeting stroke, providing a new idea for the prevention and treatment of cerebral ischemia.

Lipids and Lipid Derivatives for RNA Delivery

RNA-based therapeutics have shown great promise in treating a broad spectrum of diseases through various mechanisms including knockdown of pathological genes, expression of therapeutic proteins, and programmed gene editing. Due to the inherent instability and negative-charges of RNA molecules, RNA-based therapeutics can make the most use of delivery systems to overcome biological barriers and to release the RNA payload into the cytosol. Among different types of delivery systems, lipid-based RNA delivery systems, particularly lipid nanoparticles (LNPs), have been extensively studied due to their unique properties, such as simple chemical synthesis of lipid components, scalable manufacturing processes of LNPs, and wide packaging capability. LNPs represent the most widely used delivery systems for RNA-based therapeutics, as evidenced by the clinical approvals of three LNP-RNA formulations, patisiran, BNT162b2, and mRNA-1273. This review covers recent advances of lipids, lipid derivatives, and lipid-derived macromolecules used in RNA delivery over the past several decades. We focus mainly on their chemical structures, synthetic routes, characterization, formulation methods, and structure-activity relationships. We also briefly describe the current status of representative preclinical studies and clinical trials and highlight future opportunities and challenges.

COVID-19 Infection and Circulating Microparticles-Reviewing Evidence as Microthrombogenic Risk Factor for Cerebral Small Vessel Disease

Severe acute respiratory syndrome corona virus-2 (SARS-CoV-2) due to novel coronavirus disease 2019 (COVID-19) has affected the global society in numerous unprecedented ways, with considerable morbidity and mortality. Both direct and indirect consequences from COVID-19 infection are recognized to give rise to cardio- and cerebrovascular complications. Despite current limited knowledge on COVID-19 pathogenesis, inflammation, endothelial dysfunction, and coagulopathy appear to play critical roles in COVID-19-associated cerebrovascular disease (CVD). One of the major subtypes of CVD is cerebral small vessel disease (CSVD) which represents a spectrum of pathological processes of various etiologies affecting the brain microcirculation that can trigger subsequent neuroinflammation and neurodegeneration. Prevalent with aging, CSVD is a recognized risk factor for stroke, vascular dementia, and Alzheimer's disease. In the background of COVID-19 infection, the heightened cellular activations from inflammations and oxidative stress may result in elevated levels of microthrombogenic extracellular-derived circulating microparticles (MPs). Consequently, MPs could act as pro-coagulant risk factor that may serve as microthrombi for the vulnerable microcirculation in the brain leading to CSVD manifestations. This review aims to appraise the accumulating body of evidence on the plausible impact of COVID-19 infection on the formation of microthrombogenic MPs that could lead to microthrombosis in CSVD manifestations, including occult CSVD which may last well beyond the pandemic era.

Isolation and characterization of exosomes from adipose tissue-derived mesenchymal stem cells

Mesenchymal stem cells (MSCs) are the subject of intense research as they are a potential therapeutic tool for several clinical applications. The new MSCs action models are focused on the use of MSC-derived secretome which contains several growth factors, cytokines, microRNAs, and extracellular vesicles such as exosomes. Exosomes have recently emerged as a component with great potential involved as mediators in cellular communication. The isolation and identification of exosomes has made it possible for them to be used in cell-free therapies. The purposes of this study are: (i) to detect exosomes released into adipose-derived MSC conditioned cell culture medium, (ii) to identify exosome morphology, and (iii) to carry out a complete characterization of said exosomes. Moreover, it is aimed at determining which method for exosome isolation would be best to use. Precipitation has been identified as a highly useful method of exosome isolation since it provides higher efficiency and purity values than other methods. A broad characterization of the exosomes present in the MSC-conditioned medium was also carried out. This work fills a gap in the existing literature on bioactive molecules which have attracted a great deal of interest due to their potential use in cellular therapies.

The role of differentially expressed salivary microRNA in oral squamous cell carcinoma. A systematic review

OBJECTIVE

This study aims to systematically review the role of differentially expressed microRNA (miRNA) in saliva as potential biomarkers in oral cancer patients.

DESIGN

PubMed, Scopus and EBSCO online data bases were used as well as manual searching to extract studies from January 2008 up to October 2020.

RESULTS

A total of 14 studies that met the eligibility criteria were included. All selected studies were of case-control type. A total of 25 differentially expressed miRNAs were identified. Thirteen of these miRNAs (Let-7a, miR 27, miR 34, miR 92, miR 124, miR 125a, miR 136, miR139 miR 145, miR 146a, miR 200a, miR 205 and miR 375) were downregulated and other twelve (miR 9, miR 21, miR 31, miR 122, miR 134, miR 184, miR 191, miR 196a, miR 196b, miR 412, miR 512 and miR 8392) were upregulated. Four miRNAs were evaluated in more than one study (miR21, miR31, miR125 and miR 200).

CONCLUSION

According to these results, salivary miRNA can aid in diagnosis and prognosis of oral squamous cell carcinoma (OSCC). However, controlled clinical trials with a large sample size are required to validate the differentially expressed miRNAs of the present review.

Platelet-rich plasma as an effective biological therapy in early-stage knee osteoarthritis: One year follow up

Objective: PRP is produced by centrifugation of whole blood containing highly concentrated platelets, associated growth factors, and other bioactive agents which has been shown to provide some symptomatic relief in early knee osteoarthritis (OA). The principal objective of our study was to evaluate the effectiveness and safety of standardized intra-articular injection of autologous PRP in early osteoarthritis knee. Methods: A total of 98 eligible symptomatic patients received two injections of standardized PRP 3 weeks apart. Clinical outcomes were evaluated using the VAS and Western Ontario and McMaster Universities Arthritis Index (WOMAC) questionnaire before treatment and at 6 weeks, 3 months, 6 months, and 1 year after treatment. Secondary objectives were safety (side effects), and the effect of PRP on the different grades of knee degeneration. Results: There was a statistically significant improvement in mean VAS and WOMAC scores at 6 weeks, 3 months, 6 months, and slight loss of improvement at 1 year follow-up. There was also a correlation between the degree of degeneration and improvement in the mean scores. The decrease in mean pain score is more in grades 1 and 2 (early OA) than in grade 3. The intraarticular injection is safe, with no major complications. Conclusion: PRP is a safe and effective biological regenerative therapy for early OA Knees. It provides a significant clinical improvement in patients with some loss of improvement with time. More studies will be needed to confirm our findings.

Extracellular vesicle cargo of the male reproductive tract and the paternal preconception environment

The molecular composition of extracellular vesicles (EVs) is emerging as a novel biomarker in many areas of research including reproductive health. EVs transport biological molecules such as RNA and protein to facilitate cell-to-cell communication among cells of the male reproductive tract. Human and animal studies have shown that EVs present in seminal plasma or in the male reproductive tract contain important cargo that are important for successful reproductive outcomes. Small non-coding RNAs (sncRNA) have been at the forefront of this research, and as such, they have the potential to serve as novel biomarkers of male infertility diagnosis and reproductive success. This review provides an overview of EV biosynthesis and examines the molecular payloads of seminal plasma EVs on male infertility and reproductive success as well as future research that is warranted to examine how these molecular payloads may be modified by environmental factors.

Diets and Cellular-Derived Microparticles: Weighing a Plausible Link With Cerebral Small Vessel Disease

Cerebral small vessel disease (CSVD) represents a spectrum of pathological processes of various etiologies affecting the brain microcirculation that can trigger neuroinflammation and the subsequent neurodegenerative cascade. Prevalent with aging, CSVD is a recognized risk factor for stroke, vascular dementia, Alzheimer disease, and Parkinson disease. Despite being the most common neurodegenerative condition with cerebrocardiovascular axis, understanding about it remains poor. Interestingly, modifiable risk factors such as unhealthy diet including high intake of processed food, high-fat foods, and animal by-products are known to influence the non-neural peripheral events, such as in the gastrointestinal tract and cardiovascular stress through cellular inflammation and oxidation. One key outcome from such events, among others, includes the cellular activations that lead to elevated levels of endogenous cellular-derived circulating microparticles (MPs). MPs can be produced from various cellular origins including leukocytes, platelets, endothelial cells, microbiota, and microglia. MPs could act as microthrombogenic procoagulant that served as a plausible culprit for the vulnerable end-artery microcirculation in the brain as the end-organ leading to CSVD manifestations. However, little attention has been paid on the potential role of MPs in the onset and progression of CSVD spectrum. Corroboratively, the formation of MPs is known to be influenced by diet-induced cellular stress. Thus, this review aims to appraise the body of evidence on the dietary-related impacts on circulating MPs from non-neural peripheral origins that could serve as a plausible microthrombosis in CSVD manifestation as a precursor of neurodegeneration. Here, we elaborate on the pathomechanical features of MPs in health and disease states; relevance of dietary patterns on MP release; preclinical studies pertaining to diet-based MPs contribution to disease; MP level as putative surrogates for early disease biomarkers; and lastly, the potential of MPs manipulation with diet-based approach as a novel preventive measure for CSVD in an aging society worldwide.

TLR4 signaling induces the release of microparticles by tumor cells that regulate inflammatory cytokine IL-6 of macrophages via microRNA let-7b

Tumor cells expressing TLRs is generally recognized to mediate tumor inflammation. However, whether and how tumor TLR signaling pathways negatively regulate tumor inflammation remains unclear. In this report, we find that TLR4 signaling of H22 hepatocarcinoma tumor cells is transduced through MyD88 pathway to actin cytoskeletons, leading to the release of microparticles (MPs), the cellular membrane-derived vesicles. As a result, tumor macrophages take up MPs and acquire MP-contained microRNA let-7b, which attenuates tumor inflammation by targeting proinflammatory cytokine IL-6. Thus, tumor TLR signaling, contrary to the original promoting effect, may play an opposite role in downregulating tumor inflammation through MP pathways.

Extracellular vesicles from human cardiovascular progenitors trigger a reparative immune response in infarcted hearts

AIMS

The cardioprotective effects of human induced pluripotent stem cell-derived cardiovascular progenitor cells (CPC) are largely mediated by the paracrine release of extracellular vesicles (EV). We aimed to assess the immunological behaviour of EV-CPC, which is a prerequisite for their clinical translation.

METHODS AND RESULTS

Flow cytometry demonstrated that EV-CPC expressed very low levels of immune relevant molecules including HLA Class I, CD80, CD274 (PD-L1), and CD275 (ICOS-L); and moderate levels of ligands of the natural killer (NK) cell activating receptor, NKG2D. In mixed lymphocyte reactions, EV-CPC neither induced nor modulated adaptive allogeneic T cell immune responses. They also failed to induce NK cell degranulation, even at high concentrations. These in vitro effects were confirmed in vivo as repeated injections of EV-CPC did not stimulate production of immunoglobulins or affect the interferon (IFN)-γ responses from primed splenocytes. In a mouse model of chronic heart failure, intra-myocardial injections of EV-CPC, 3 weeks after myocardial infarction, decreased both the number of cardiac pro-inflammatory Ly6Chigh monocytes and circulating levels of pro-inflammatory cytokines (IL-1α, TNF-α, and IFN-γ). In a model of acute infarction, direct cardiac injection of EV-CPC 2 days after infarction reduced pro-inflammatory macrophages, Ly6Chigh monocytes, and neutrophils in heart tissue as compared to controls. EV-CPC also reduced levels of pro-inflammatory cytokines IL-1α, IL-2, and IL-6, and increased levels of the anti-inflammatory cytokine IL-10. These effects on human macrophages and monocytes were reproduced in vitro; EV-CPC reduced the number of pro-inflammatory monocytes and M1 macrophages, while increasing the number of anti-inflammatory M2 macrophages.

CONCLUSIONS

EV-CPC do not trigger an immune response either in in vitro human allogeneic models or in immunocompetent animal models. The capacity for orienting the response of monocyte/macrophages towards resolution of inflammation strengthens the clinical attractiveness of EV-CPC as an acellular therapy for cardiac repair.

Extracellular vesicles for treatment of solid organ ischemia-reperfusion injury

As the incidence of ischemia-reperfusion (I-R) injury has substantially increased, there is a pressing need to develop effective strategies to treat this global health issue. I-R injury can affect all organs and is associated with high morbidity and mortality rates. Pathological settings such as myocardial infarction, stroke, hemorrhagic shock, and solid organ transplant are particularly prone to cause I-R injury. Ischemia (hypoxia) and/or reperfusion (reoxygenation) induces various forms of cellular and structural damage. A major cause of damage is local inflammatory responses, which may spread to produce more advanced systemic inflammation. Management of I-R injury relies primarily on supportive measures, as specific treatment strategies are lacking. Extracellular vesicles (EVs) are cell-secreted nano-scale structures containing various biomolecules involved in cell communication and multiple physiological processes. EVs derived from certain cell types have been shown to exhibit anti-inflammatory, antioxidant, and angiogenic properties. This review provides an overview of EV-based therapeutics for I-R injury in kidneys, liver, heart, lungs, and brain. Additionally, the mechanisms by which EVs protect against I-R injury are discussed. Promising preclinical findings highlight the potential clinical use of EVs for I-R injury.

Cell Therapy With Human ESC-Derived Cardiac Cells: Clinical Perspectives

In the ongoing quest for the “ideal” cell type for heart repair, pluripotent stem cells (PSC) derived from either embryonic or reprogrammed somatic cells have emerged as attractive candidates because of their unique ability to give rise to lineage-specific cells and to transplant them at the desired stage of differentiation. The technical obstacles which have initially hindered their clinical use have now been largely overcome and several trials are under way which encompass several different diseases, including heart failure. So far, there have been no safety warning but it is still too early to draw definite conclusions regarding efficacy. In parallel, mechanistic studies suggest that the primary objective of “remuscularizing” the heart with PSC-derived cardiac cells can be challenged by their alternate use as ex vivo sources of a biologically active extracellular vesicle-enriched secretome equally able to improve heart function through harnessing endogenous repair pathways. The exclusive use of this secretome would combine the advantages of a large-scale production more akin to that of a biological medication, the likely avoidance of cell-associated immune and tumorigenicity risks and the possibility of intravenous infusions compatible with repeated dosing.

Natural Biomaterials for Cardiac Tissue Engineering: A Highly Biocompatible Solution

Cardiovascular diseases (CVD) constitute a major fraction of the current major global diseases and lead to about 30% of the deaths, i.e., 17.9 million deaths per year. CVD include coronary artery disease (CAD), myocardial infarction (MI), arrhythmias, heart failure, heart valve diseases, congenital heart disease, and cardiomyopathy. Cardiac Tissue Engineering (CTE) aims to address these conditions, the overall goal being the efficient regeneration of diseased cardiac tissue using an ideal combination of biomaterials and cells. Various cells have thus far been utilized in pre-clinical studies for CTE. These include adult stem cell populations (mesenchymal stem cells) and pluripotent stem cells (including autologous human induced pluripotent stem cells or allogenic human embryonic stem cells) with the latter undergoing differentiation to form functional cardiac cells. The ideal biomaterial for cardiac tissue engineering needs to have suitable material properties with the ability to support efficient attachment, growth, and differentiation of the cardiac cells, leading to the formation of functional cardiac tissue. In this review, we have focused on the use of biomaterials of natural origin for CTE. Natural biomaterials are generally known to be highly biocompatible and in addition are sustainable in nature. We have focused on those that have been widely explored in CTE and describe the original work and the current state of art. These include fibrinogen (in the context of Engineered Heart Tissue, EHT), collagen, alginate, silk, and Polyhydroxyalkanoates (PHAs). Amongst these, fibrinogen, collagen, alginate, and silk are isolated from natural sources whereas PHAs are produced via bacterial fermentation. Overall, these biomaterials have proven to be highly promising, displaying robust biocompatibility and, when combined with cells, an ability to enhance post-MI cardiac function in pre-clinical models. As such, CTE has great potential for future clinical solutions and hence can lead to a considerable reduction in mortality rates due to CVD.

Differential Expression of microRNA Profiles and Wnt Signals in Stem Cell-Derived Exosomes During Dopaminergic Neuron Differentiation

The role of secreted exosomes during dopaminergic (DA) neuron differentiation is still unknown. To investigate the roles of exosomes in DA neuron fate specification, we profiled exosomal microRNAs (miRNAs) during DA neuron differentiation of epiblast-derived stem cells (EpiSCs). There were 26 miRNAs differentially expressed (relative fold >2, p < 0.05) in EpiSC-derived exosomes at 0, 2, 4, 6, 8, 10, 12, and 14 days of DA epiblast differentiation. Among them, 23 exosomic miRNAs were significantly increased, including miR-124, miR-132, miR-133b, miR-218, miR-9, miR-34b, miR-34c, and miR-135a2, while three exosomic miRNAs (miR-214, miR-7a, and miR-302b) were decreased, when compared with control samples. Bioinformatics analysis by DIANA-mirPath demonstrated that extracellular matrix-receptor interaction, signaling pathways regulating pluripotency of stem cells, FoxO signaling pathway, DA synapse, Wnt signaling pathway, GABAergic synapse, and neurotrophin signaling pathway were significantly enriched in DA differentiation-related miRNA signature (all p-values <0.012). Furthermore, messenger RNAs for nine DA neuronal markers tyrosine hydroxylase (TH), Nr4a2, Pitx3, Drd1a, Lmx1a, Lmx1b, Foxa1, Dmrt5, and Slc18a2 were significantly increased expressed over time in exosomes derived from differentiated EpiSCs. Interestingly, adding with exosomes derived from EpiSC induction experiment resulted in a twofold increase of TH-positive neurons production (35% vs. 17%, p < 0.01) during DA neuronal differentiation from mouse embryonic stem cells (ESCs). In summary, our results suggested exosomal miRNAs are potential regulators of DA neuron differentiation. More importantly, EpiSC-derived exosomes could promote the generation of DA neuron differentiation from ESCs.

Circulating microRNA as a Biomarker for Coronary Artery Disease

Coronary artery disease (CAD) is the leading cause of sudden cardiac death in adults, and new methods of predicting disease and risk-stratifying patients will help guide intervention in order to reduce this burden. Current CAD detection involves multiple modalities, but the consideration of other biomarkers will help improve reliability. The aim of this narrative review is to help researchers and clinicians appreciate the growing relevance of miRNA in CAD and its potential as a biomarker, and also to suggest useful miRNA that may be targets for future study. We sourced information from several databases, namely PubMed, Scopus, and Google Scholar, when collating evidentiary information. MicroRNAs (miRNA) are short, noncoding RNAs that are relevant in cardiovascular physiology and pathophysiology, playing roles in cardiac hypertrophy, maintenance of vascular tone, and responses to vascular injury. CAD is associated with changes in miRNA expression profiles, and so are its risk factors, such as abnormal lipid metabolism and inflammation. Thus, they may potentially be biomarkers of CAD. Nevertheless, there are limitations in using miRNA. These include cost and the presence of several confounding factors that may affect miRNA profiles. Furthermore, there is difficulty in the normalisation of miRNA values between published studies, due to pre-analytical variations in samples.

Clinical Translation of Pluripotent Stem Cell Therapies: Challenges and Considerations

Although the clinical outcomes of cell therapy trials have not met initial expectations, emerging evidence suggests that injury-mediated tissue damage might benefit from the delivery of cells or their secreted products. Pluripotent stem cells (PSCs) are promising cell sources primarily because of their capacity to generate stage- and lineage-specific differentiated derivatives. However, they carry inherent challenges for safe and efficacious clinical translation. This Review describes completed or ongoing trials of PSCs, discusses their potential mechanisms of action, and considers how to address the challenges required for them to become a major therapy, using heart repair as a case study.

Exosomes derived from P2X7 receptor gene-modified cells rescue inflammation-compromised periodontal ligament stem cells from dysfunction

Although cellular therapy has been proposed for inflammation‐related disorders such as periodontitis for decades, clinical application has been unsuccessful. One explanation for these disappointing results is that the functions of stem cells are substantially compromised when they are transplanted into an inflammatory in vivo milieu. Considering the previous finding that P2X7 receptor (P2X7R) gene modification is able to reverse inflammation‐mediated impairment of periodontal ligament stem cells (PDLSCs), we further hypothesized that cells subjected to P2X7R gene transduction also exert influences on other cells within an in vivo milieu via an exosome‐mediated paracrine mechanism. To define the paracrine ability of P2X7R gene‐modified cells, P2X7R gene‐modified stem cell‐derived conditional medium (CM‐Ad‐P2X7) and exosomes (Exs‐Ad‐P2X7) were used to incubate PDLSCs. In an inflammatory osteogenic microenvironment, inflammation‐mediated changes in PDLSCs were substantially reduced, as shown by quantitative real‐time PCR (qRT‐PCR) analysis, Western blot analysis, alkaline phosphatase (ALP) staining/activity assays, and Alizarin red staining. In addition, the Agilent miRNA microarray system combined with qRT‐PCR analysis revealed that miR‐3679‐5p, miR‐6515‐5p, and miR‐6747‐5p were highly expressed in Exs‐Ad‐P2X7. Further functional tests and luciferase reporter assays revealed that miR‐3679‐5p and miR‐6747‐5p bound directly to the GREM‐1 protein, while miR‐6515‐5p bound to the GREM‐1 protein indirectly; these effects combined to rescue inflammation‐compromised PDLSCs from dysfunction. Thus, in addition to maintaining their robust functionality under inflammatory conditions, P2X7R gene‐modified stem cells may exert positive influences on their neighbors via a paracrine mechanism, pointing to a novel strategy for modifying the harsh local microenvironment to accommodate stem cells and promote improved tissue regeneration.

Analysis of Adult Neural Retina Extracellular Vesicle Release, RNA Transport and Proteomic Cargo

Purpose

Extracellular vesicles (EVs) contain RNA and protein cargo reflective of the genotype and phenotype of the releasing cell of origin. Adult neural retina EV release, RNA transfer, and proteomic cargo are the focus of this study.

Methods

Adult wild-type mouse retinae were cultured and released EV diameters and concentrations quantified using Nanosight. Immunogold transmission electron microscopy (TEM) was used to image EV ultrastructure and marker protein localization. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to analyze retinal cell transcripts present in EVs. Super-resolution microscopy was used to image fluorescent (green) RNA and (red) lipid membrane labeled EVs, released by adult retina, and internalized by isolated retinal cells. Mass spectrometry was used to characterize the proteomes of adult retina and EVs.

Results

Adult neural retina released EVs at a rate of 1.42 +/- 0.08 × 108/mL over 5 days, with diameters ranging from 30 to 910 nm. The canonical EV markers CD63 and Tsg101 localized to retinal EVs. Adult retinal and neuronal mRNA species present in both retina and EVs included rhodopsin and the neuronal nuclei marker NeuN. Fluorescently labeled RNA in retinal cells was enclosed in EVs, transported to, and uptaken by co-cultured adult retinal cells. Proteomic analysis revealed 1696 protein species detected only in retinal cells, 957 species shared between retina and EVs, and 82 detected only in EVs.

Conclusions

The adult neural retina constitutively releases EVs with molecular cargo capable of intercellular transport and predicted involvement in biological processes including retinal physiology, mRNA processing, and transcription regulation within the retinal microenvironment.

Regenerative abilities of mesenchymal stem cells via acting as an ideal vehicle for subcellular component delivery in acute kidney injury

Cell‐to‐cell communication and information exchange is one of the most important events in multiple physiological processes, including multicellular organism development, cellular function regulation, external stress response, homeostasis maintenance and tissue regeneration. New findings support the concept that subcellular component delivery may account for the beneficial effects of mesenchymal stem cell (MSC)‐based therapy‐mediated protection against acute kidney injury (AKI). Through the secretion of extracellular vesicles (EVs), formation of tunnelling nanotubes (TNTs) and development of cellular fusions, a broad range of subcellular components, including proteins, nucleic acids (mRNA and miRNA) or even organelles can be transferred from MSCs into injured renal cells, significantly promoting cell survival, favouring tissue repair and accelerating renal recovery. In this review, we outline an extensive and detailed description of the regenerative consequences of subcellular component delivery from MSCs into injured renal cells during AKI, by which the potential mechanism underlying MSC‐based therapies against AKI can be elucidated.

Circulating Small Noncoding RNAs Have Specific Expression Patterns in Plasma and Extracellular Vesicles in Myelodysplastic Syndromes and Are Predictive of Patient Outcome

Myelodysplastic syndromes (MDS) are hematopoietic stem cell disorders with large heterogeneity at the clinical and molecular levels. As diagnostic procedures shift from bone marrow biopsies towards less invasive techniques, circulating small noncoding RNAs (sncRNAs) have become of particular interest as potential novel noninvasive biomarkers of the disease. We aimed to characterize the expression profiles of circulating sncRNAs of MDS patients and to search for specific RNAs applicable as potential biomarkers. We performed small RNA-seq in paired samples of total plasma and plasma-derived extracellular vesicles (EVs) obtained from 42 patients and 17 healthy controls and analyzed the data with respect to the stage of the disease, patient survival, response to azacitidine, mutational status, and RNA editing. Significantly higher amounts of RNA material and a striking imbalance in RNA content between plasma and EVs (more than 400 significantly deregulated sncRNAs) were found in MDS patients compared to healthy controls. Moreover, the RNA content of EV cargo was more homogeneous than that of total plasma, and different RNAs were deregulated in these two types of material. Differential expression analyses identified that many hematopoiesis-related miRNAs (e.g., miR-34a, miR-125a, and miR-150) were significantly increased in MDS and that miRNAs clustered on 14q32 were specifically increased in early MDS. Only low numbers of circulating sncRNAs were significantly associated with somatic mutations in the SF3B1 or DNMT3A genes. Survival analysis defined a signature of four sncRNAs (miR-1237-3p, U33, hsa_piR_019420, and miR-548av-5p measured in EVs) as the most significantly associated with overall survival (HR = 5.866, p < 0.001). In total plasma, we identified five circulating miRNAs (miR-423-5p, miR-126-3p, miR-151a-3p, miR-125a-5p, and miR-199a-3p) whose combined expression levels could predict the response to azacitidine treatment. In conclusion, our data demonstrate that circulating sncRNAs show specific patterns in MDS and that their expression changes during disease progression, providing a rationale for the potential clinical usefulness of circulating sncRNAs in MDS prognosis. However, monitoring sncRNA levels in total plasma or in the EV fraction does not reflect one another, instead, they seem to represent distinctive snapshots of the disease and the data should be interpreted circumspectly with respect to the type of material analyzed.

Resolvin D1 Modulates the Intracellular VEGF-Related miRNAs of Retinal Photoreceptors Challenged With High Glucose

Stimulation of retinal photoreceptors with elevated glucose concentration (30 mM) for 96 h, served as diabetic retinopathy in vitro model to study Resolvin D1 (50 nM) effects on neovascularization. VEGF and anti-angiogenic miR-20a-3p, miR-20a-5p, miR-106a-5p, and miR-20b expression was assessed either in photoreceptors exposed to HG or in exosomes released by those cells. High glucose increased VEGF levels and concurrently decreased anti-angiogenic miRNAs content in photoreceptors and exosomes. RvD1 reverted the effects of glucose damage in photoreceptors and exosomal pro-angiogenic potential, tested with the HUVEC angiogenesis assay. By activating FPR2 receptor, RvD1 modulated both the expression of anti-angiogenic miRNA, which decrease VEGF, and the pro-angiogenic potential of exosomes released by primary retinal cells. HUVEC transfection with miR-20a-3p, miR-20a-5p, miR-106a-5p, and miR-20b antagomirs, followed by exposure to exosomes from photoreceptors, confirmed the VEGF-related miRNAs mechanism and the anti-angiogenic effects of RvD1.

Targeting cancer stem cell pathways for cancer therapy

Since cancer stem cells (CSCs) were first identified in leukemia in 1994, they have been considered promising therapeutic targets for cancer therapy. These cells have self-renewal capacity and differentiation potential and contribute to multiple tumor malignancies, such as recurrence, metastasis, heterogeneity, multidrug resistance, and radiation resistance. The biological activities of CSCs are regulated by several pluripotent transcription factors, such as OCT4, Sox2, Nanog, KLF4, and MYC. In addition, many intracellular signaling pathways, such as Wnt, NF-κB (nuclear factor-κB), Notch, Hedgehog, JAK-STAT (Janus kinase/signal transducers and activators of transcription), PI3K/AKT/mTOR (phosphoinositide 3-kinase/AKT/mammalian target of rapamycin), TGF (transforming growth factor)/SMAD, and PPAR (peroxisome proliferator-activated receptor), as well as extracellular factors, such as vascular niches, hypoxia, tumor-associated macrophages, cancer-associated fibroblasts, cancer-associated mesenchymal stem cells, extracellular matrix, and exosomes, have been shown to be very important regulators of CSCs. Molecules, vaccines, antibodies, and CAR-T (chimeric antigen receptor T cell) cells have been developed to specifically target CSCs, and some of these factors are already undergoing clinical trials. This review summarizes the characterization and identification of CSCs, depicts major factors and pathways that regulate CSC development, and discusses potential targeted therapy for CSCs.

Targeting Purinergic Signaling and Cell Therapy in Cardiovascular and Neurodegenerative Diseases

Extracellular purines exert several functions in physiological and pathophysiological mechanisms. ATP acts through P2 receptors as a neurotransmitter and neuromodulator and modulates heart contractility, while adenosine participates in neurotransmission, blood pressure, and many other mechanisms. Because of their capability to differentiate into mature cell types, they provide a unique therapeutic strategy for regenerating damaged tissue, such as in cardiovascular and neurodegenerative diseases. Purinergic signaling is pivotal for controlling stem cell differentiation and phenotype determination. Proliferation, differentiation, and apoptosis of stem cells of various origins are regulated by purinergic receptors. In this chapter, we selected neurodegenerative and cardiovascular diseases with clinical trials using cell therapy and purinergic receptor targeting. We discuss these approaches as therapeutic alternatives to neurodegenerative and cardiovascular diseases. For instance, promising results were demonstrated in the utilization of mesenchymal stem cells and bone marrow mononuclear cells in vascular regeneration. Regarding neurodegenerative diseases, in general, P2X7 and A_2A receptors mostly worsen the degenerative state. Stem cell-based therapy, mainly through mesenchymal and hematopoietic stem cells, showed promising results in improving symptoms caused by neurodegeneration. We propose that purinergic receptor activity regulation combined with stem cells could enhance proliferative and differentiation rates as well as cell engraftment.

Exosomes derived from HeLa cells break down vascular integrity by triggering endoplasmic reticulum stress in endothelial cells

Exosomes play a critical role in intercellular communication since they contain signalling molecules and genetic materials. During tumorigenesis, tumour-derived exosomes have been demonstrated to promote tumour angiogenesis and metastasis. However, how the exosomes facilitate tumour metastasis is not clear. Here we explored the effect of HeLa cell-derived exosomes (Exo^HeLa) on endothelial tight junctions (TJ) and the related mechanisms. After human umbilical vein endothelial cells (HUVEC) were treated with Exo^HeLa, TJ proteins zonula occludens-1 (ZO-1) and Claudin-5 in HUVEC were significantly reduced as compared with that treated with exosomes from human cervical epithelial cells, while mRNA levels of ZO-1 and Claudin-5 remained unchanged. Consequently, permeability of endothelial monolayer was increased after the treatment with Exo^HeLa. Injection of Exo^HeLa into mice also increased vascular permeability and tumour metastasis in vivo. Neither knocking down of Dicer nor use of inhibitors of microRNAs targeting at mRNAs of ZO-1 and Claudin-5 could block the inhibitory effect of Exo^HeLa on ZO-1 and Claudin-5. The expression of genes involved in endoplasmic reticulum (ER) stress was significantly increased in HUVECs after treated with Exo^HeLa. Inhibition of ER stress by knocking down protein kinase RNA-like endoplasmic reticulum kinase prevented the down-regulation of ZO-1 and Claudin-5 by Exo^HeLa. Our study found that HeLa cell-derived exosomes promote metastasis by triggering ER stress in endothelial cells and break down endothelial integrity. Such effect of exosomes is microRNA-independent.

Exosomal Thrombospondin-1 Disrupts the Integrity of Endothelial Intercellular Junctions to Facilitate Breast Cancer Cell Metastasis

Transendothelial migration of malignant cells plays an essential role in tumor progression and metastasis. The present study revealed that treating human umbilical vein endothelial cells (HUVECs) with exosomes derived from metastatic breast cancer cells increased the number of cancer cells migrating through the endothelial cell layer and impaired the tube formation of HUVECs. Furthermore, the expression of intercellular junction proteins, including vascular endothelial cadherin (VE-cadherin) and zona occluden-1 (ZO-1), was reduced significantly in HUVECs treated with carcinoma-derived exosomes. Proteomic analyses revealed that thrombospondin-1 (TSP1) was highly expressed in breast cancer cell MDA-MB-231-derived exosomes. Treating HUVECs with TSP1-enriched exosomes similarly promoted the transendothelial migration of malignant cells and decreased the expression of intercellular junction proteins. TSP1-down regulation abolished the effects of exosomes on HUVECs. The migration of breast cancer cells was markedly increased in a zebrafish in vivo model injected with TSP1-overexpressing breast cancer cells. Taken together, these results suggest that carcinoma-derived exosomal TSP1 facilitated the transendothelial migration of breast cancer cells via disrupting the intercellular integrity of endothelial cells.

Acellular therapeutic approach for heart failure: in vitro production of extracellular vesicles from human cardiovascular progenitors

Aims

We have shown that extracellular vesicles (EVs) secreted by embryonic stem cell-derived cardiovascular progenitor cells (Pg) recapitulate the therapeutic effects of their parent cells in a mouse model of chronic heart failure (CHF). Our objectives are to investigate whether EV released by more readily available cell sources are therapeutic, whether their effectiveness is influenced by the differentiation state of the secreting cell, and through which mechanisms they act.

Methods and results

The total EV secreted by human induced pluripotent stem cell-derived cardiovascular progenitors (iPSC-Pg) and human induced pluripotent stem cell-derived cardiomyocytes (iPSC-CM) were isolated by ultracentrifugation and characterized by Nanoparticle Tracking Analysis, western blot, and cryo-electron microscopy. In vitro bioactivity assays were used to evaluate their cellular effects. Cell and EV microRNA (miRNA) content were assessed by miRNA array. Myocardial infarction was induced in 199 nude mice. Three weeks later, mice with left ventricular ejection fraction (LVEF) ≤ 45% received transcutaneous echo-guided injections of iPSC-CM (1.4 × 106, n = 19), iPSC-Pg (1.4 × 106, n = 17), total EV secreted by 1.4 × 106 iPSC-Pg (n = 19), or phosphate-buffered saline (control, n = 17) into the peri-infarct myocardium. Seven weeks later, hearts were evaluated by echocardiography, histology, and gene expression profiling, blinded to treatment group. In vitro, EV were internalized by target cells, increased cell survival, cell proliferation, and endothelial cell migration in a dose-dependent manner and stimulated tube formation. Extracellular vesicles were rich in miRNAs and most of the 16 highly abundant, evolutionarily conserved miRNAs are associated with tissue-repair pathways. In vivo, EV outperformed cell injections, significantly improving cardiac function through decreased left ventricular volumes (left ventricular end systolic volume: -11%, P < 0.001; left ventricular end diastolic volume: -4%, P = 0.002), and increased LVEF (+14%, P < 0.0001) relative to baseline values. Gene profiling revealed that EV-treated hearts were enriched for tissue reparative pathways.

Conclusion

Extracellular vesicles secreted by iPSC-Pg are effective in the treatment of CHF, possibly, in part, through their specific miRNA signature and the associated stimulation of distinct cardioprotective pathways. The processing and regulatory advantages of EV could make them effective substitutes for cell transplantation.

Identification of miRNAs from stem cell derived microparticles in umbilical cord blood

Umbilical cord blood CD34+ (UCB-CD34+) stem cells are clinically used in hematopoietic cell transplantation. However, there are limitations in the use of umbilical cord blood transplants because of the small number of cells and delayed engraftment. To gain a better understanding of functional components of UCB, we have detected and characterized CD34+ microparticles (CD34+MPs) from cord blood units. We collected cord blood units and assessed the numbers of CD34+MPs before and after red blood cell and plasma depletion by SEPAX processing using flow cytometry analysis. In parallel we identified MPs by electron microscopy. CD34+MPs and cells were isolated by MACs sorting. MicroRNAs (miR-106, miR-221, miR-517, miR-519, and miR-221) exhibited a characteristic microRNA profile that was further validated in isolated CD34+MPs. We found that in cord blood, there are CD34+MPs that carry microRNAs.

Platelet Oxidative Stress and its Relationship with Cardiovascular Diseases in Type 2 Diabetes Mellitus Patients

Enhanced platelet activation and thrombosis are linked to various cardiovascular diseases (CVD). Among other mechanisms, oxidative stress seems to play a pivotal role in platelet hyperactivity. Indeed, upon stimulation by physiological agonists, human platelets generate and release several types of reactive oxygen species (ROS) such as O2 -, H2O2 or OH-, further amplifying the platelet activation response via various signalling pathways, including, formation of isoprostanes, Ca2+ mobilization and NO inactivation. Furthermore, excessive platelet ROS generation, incorporation of free radicals from environment and/or depletion of antioxidants induce pro-oxidant, pro-inflammatory and platelet hyperaggregability effects, leading to the incidence of cardiovascular events. Here, we review the current knowledge regarding the effect of oxidative stress on platelet signaling pathways and its implication in CVD such as type 2 diabetes mellitus. We also summarize the role of natural antioxidants included in vegetables, fruits and medicinal herbs in reducing platelet function via an oxidative stress-mediated mechanism.

Considerations and Implications in the Purification of Extracellular Vesicles - A Cautionary Tale

Extracellular vesicles (EVs) are nano-sized particles constitutively released from cells into all biological fluids. Interestingly, these vesicles contain genetic cargoes including proteins, RNA and bioactive lipids that can be functionally delivered and affect recipient cells. As a result, there is growing interest in studying EVs in pathological conditions, including central nervous system (CNS)-related diseases, as EVs may be used for diagnostic purposes or as therapeutic agents. However, one major bottleneck is the need for better EV purification strategies when considering complex biological sources such as serum/protein-rich media or plasma. In this study, we have performed a systematic comparison study between the current gold-standard method: ultracentrifugation, to an alternative: size-exclusion chromatography (LC), using induced pluripotent stem cell (iPSC) derived complex media as a model system. We demonstrate that LC allows for derivation of purer EVs from iPSCs, which was previously impossible with the original UC method. Importantly, our study further highlights the various drawbacks when using the conventional UC approach that lead to misinterpretation of EV data. Lastly, we describe novel data on our iPSC-EVs; how they could relate to stem cell biology and discuss their potential use as EV therapeutics for CNS diseases.

The role of microvesicles containing microRNAs in vascular endothelial dysfunction

Many studies have shown that endothelial dysfunction is associated with a variety of cardiovascular diseases. The endothelium is one of the primary targets of circulating microvesicles. Besides, microRNAs emerge as important regulators of endothelial cell function. As a delivery system of microRNAs, microvesicles play an active and important role in regulating vascular endothelial function. In recent years, some studies have shown that microvesicles containing microRNAs regulate the pathophysiological changes in vascular endothelium, such as cell apoptosis, proliferation, migration and inflammation. These studies have provided some clues for the possible roles of microvesicles and microRNAs in vascular endothelial dysfunction‐associated diseases, and opened the door towards discovering potential novel therapeutic targets. In this review, we provide an overview of the main characteristics of microvesicles and microRNAs, summarizing their potential role and mechanism in endothelial dysfunction, and discussing the clinical application and existing problems of microvesicles for better translational applications.