Melatonin alleviates vascular calcification and ageing through exosomal miR-204/miR-211 cluster in a paracrine manner

Vascular wall microenvironment: Endothelial cells original exosomes mediated melatonin-suppressed vascular calcification and vascular ageing in a m6A methylation dependent manner

Vascular calcification and vascular ageing are "silent" diseases but are highly prevalent in patients with end stage renal failure and type 2 diabetes, as well as in the ageing population. Melatonin (MT) has been shown to induce cardiovascular protection effects. However, the role of MT on vascular calcification and ageing has not been well-identified. In this study, the aortic transcriptional landscape revealed clues for MT related cell-to-cell communication between endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) in vascular calcification and vascular ageing. Furthermore, we elucidated that it was exosomes that participate in the information transportation from ECs to VSMCs. The exosomes secreted from melatonin-treated ECs (MT-ECs-Exos) inhibited calcification and senescence of VSMCs. Mechanistically, miR-302d-5p was highly enriched in MT-ECs-Exos, while depletion of miR-302d-5p blocked the ability of MT-ECs-Exos to suppress VSMC calcification and senescence. Notably, Wnt3 was a bona fide target of miR-302d-5p and modulated VSMC calcification and senescence. Furthermore, we found that maturation of endothelial derived exosomal miR-302d-5p was promoted by WTAP in an N6-methyladenosine (m6A)-dependent manner. Interestingly, MT alleviated vascular calcification and ageing in 5/6-nephrectomy (5/6 NTP) mice, a chronic kidney disease (CKD) induced vascular calcification and vascular ageing mouse model. MT-ECs-Exos was absorbed by VSMCs in vivo and effectively prevented vascular calcification and ageing in 5/6 NTP mice. ECs-derived miR-302d-5p mediated MT induced anti-calcification and anti-ageing effects in 5/6 NTP mice. Our study suggests that MT-ECs-Exos alleviate vascular calcification and ageing through the miR-302d-5p/Wnt3 signaling pathway, dependent on m6A methylation.

Trans-resveratrol mitigates miR-204-3p mediated progression of allergic rhinitis by regulating the EGLN3/HIF-1α/IL33/ST2 signalling pathway

BACKGROUND

Allergic rhinitis (AR) is a multifactorial disease triggered by interactions between genes and the environment. Clinical evidence has shown that trans-resveratrol, a widely used drug, significantly ameliorates AR pathology. However, the precise mechanisms underlying this effect remain unclear.

PURPOSE

This study aimed to elucidate the pharmacological mechanisms of action of trans-resveratrol in patients with AR who exhibit hypoxic symptoms. This will be achieved through microRNA sequencing and signaling pathway screening combined with basic experiments to determine the effects of Trans-resveratrol intervention in this patient population.

METHODS

Network pharmacology was used to determine the therapeutic value of trans-resveratrol in AR. The micro-RNA miR-204-3p was pinpointed by sequencing. Quantitative reverse transcription polymerase chain reaction was used to quantify the expression levels. Haematoxylin and eosin, alcian blue-periodic acid-Schiff, and Masson's trichrome staining were used to assess the effects of hypoxia on nasal mucosa immunohistochemistry and immunofluorescence-localised target proteins. Egl nine homolog 3 (EGLN3) was screened using bioinformatics software. Protein expression was detected by western blotting. Cell growth and death were gauged via Cell Counting Kit-8 and terminal deoxynucleotidyl transferase dUTP nick end labelling staining, respectively. Cell migration was observed using a transwell assay. Enzyme-linked immunosorbent assay was used to measure interleukin (IL)33 levels in the cell supernatants. Flow cytometry was used to verify cell cycle and antigen levels. Electron microscopy was used to visualise the status of the nasal mucosa prior to in vivo expression analysis.

RESULTS

Patients with hypoxic AR demonstrated more pronounced nasal mucosal remodelling than that in patients with common AR. Sequencing results indicated that these patients had a reduced expression of miR-204-3p. Through a combination utilizing of bioinformatics analysis and experimental validation, EGLN3 has been identified as a direct target of HIF-1α. The low expression level of miR-204-3p represses EGLN3, resulting in the accumulation of HIF-1α and the activation of the IL33/ST2 signaling pathway. These stimulate the proliferation, survival, and migration of HNEpCs, ultimately contributing to mucosa remodeling and AR progression. Trans-resveratrol notably downregulated the levels of HIF-1α and IL33/ST2, while simultaneously increasing the expression of EGLN3.

CONCLUSIONS

Downregulation of miR-204-3p initiated a vicious cycle of hypoxic AR via EGLN3/HIF-1α/IL33/ST2. Trans-resveratrol reversed the pathological process of nasal mucosa remodeling of hypoxic AR by exhibiting anti-inflammatory and anti-angiogenic functions via the above signaling pathway. Our study uncovers the underlying mechanism by which hypoxia drives the progression of AR. It presents innovative strategies for addressing inflammatory and hypoxia-related diseases, bridging traditional and modern medicine, and highlighting the potential of natural compounds in clinical practice.

GHRH-stimulated pituitary small extracellular vesicles inhibit hepatocyte proliferation and IGF-1 expression by its cargo miR-375-3p

Small extracellular vesicles (sEV) have emerged as a novel mode of intercellular material transport and information transmission. It has been suggested hormones may regulate the production and function of sEV. However, the specific impact of growth hormone-releasing hormone (GHRH) on pituitary sEV production and the role of sEV in the regulation of the GHRH-GH-IGF axis has not been previously reported. The results of the present study demonstrated that GHRH increased the production of pituitary sEV by promoting the expression of Rab27a. More importantly, GHRH induced alterations in protein and miRNA levels within GH3-sEV components. Notably, GH3-sEV with GHRH treatment exhibited the enhanced ability to impede BRL 3A cell proliferation and the expression of IGF-1. Conclusively, for the first time, we corroborate the influence of GHRH on pituitary sEV, thereby presenting novel evidence for how sEV participates in the balance of the GHRH-GH-IGF axis. Importantly, this study provides new insight into a novel balance mechanism mediated by sEV within the endocrine system.

Endothelial cells derived extracellular vesicles promote diabetic arterial calcification via circ_0008362/miR-1251-5p/Runx2 axial

INTRODUCTION

Arterial calcification, an independent predictor of cardiovascular events, increases morbidity and mortality in patients with diabetes mellitus (DM), but its mechanisms remain unclear. Extracellular vesicles (EVs) play an important role in intercellular communication. The study investigates the role and potential mechanisms of EVs derived from endothelial cells (ECs) in regulating vascular smooth muscle cell (VSMC) calcification under high glucose (HG) condition, with a goal of developing effective prevention and treatment strategies for diabetic arterial calcification.

RESULTS

The results showed that EVs derived from HG induced ECs (ECHG-EVs) exhibited a bilayer structure morphology with a mean diameter of 74.08 ± 31.78 nm, expressing EVs markers including CD9, CD63 and TSG101, but not express calnexin. ECHG-EVs was internalized by VSMCs and induced VSMC calcification by increasing Runx2 expression and mineralized nodule formation. The circ_0008362 was enriched in ECHG-EVs, and it can be transmitted to VSMCs to promote VSMC calcification both in vitro and in vivo. Mechanistically, miR-1251-5p might be one of the targets of circ_0008362 and they were co-localization in the cytoplasm of VSMCs. Runx2 was identified as the downstream target of miR-1251-5p, and circ_0008362 acted as a sponge, enhancing Runx2 expression and then promoted VSMC calcification. Besides, circ_0008362 could directly interact with Runx2 to aggravate VSMC calcification. Notably, DiR-labelled ECHG-EVs was detected in the vessels of mice. Meanwhile, the level of circ_0008362 and Runx2 were increased significantly, while the expression of miR-1251-5p was decreased significantly in calcified artery tissues of mice. However, inhibiting the release of EVs by GW4869 attenuated arterial calcification in diabetic mice. Finally, the level of circulation of plasma EVs circ_0008362 was significantly higher in patients with DM compared with normal controls. Elevated levels of plasma EVs circ_0008362 were associated with more severe coronary and aorta artery calcification in patients with DM.

CONCLUSIONS

Our findings suggested that circ_0008362 was enriched in EVs derived from ECs and promoted VSMC calcification under HG conditions, both by sponging miR-1251-5p to upregulate Runx2 expression and through direct interaction with Runx2. Furthermore, elevated levels of plasma EVs circ_0008362 were associated with more severe coronary and aorta artery calcification in patients with DM. These results may serve as a potential prevention and therapeutic target for diabetic arterial calcification.

Cold Exposure Alleviates T2DM Through Plasma-Derived Extracellular Vesicles

Purpose

Anecdotal reports have praised the benefits of cold exposure, exemplified by activities like winter swimming and cold water immersion. Cold exposure has garnered acclaim for its potential to confer benefits and potentially alleviate diabetes. We posited that systemic cold temperature (CT, 4-8°C) likely influences the organism's blood components through ambient temperature, prompting our investigation into the effects of chronic cold exposure on type 2 diabetic (T2DM) mice and our initial exploration of how cold exposure mitigates the incidence of T2DM.

Methods

The effects of CT (4-8°C) or room temperature (RT, 22-25°C) on T2DM mice were investigated. Mice blood and organ specimens were collected for fully automated biochemical testing, ELISA, HE staining, immunohistochemistry, and immunofluorescence. Glucose uptake was assessed using flow cytometry with 2-NBDG. Changes in potential signaling pathways such as protein kinase B (AKT), phosphorylated AKT (p-AKT), insulin receptor substrates 1 (IRS1), and phosphorylated IRS1 (p-IRS1) were evaluated by Western blot.

Results

CT or CT mice plasma-derived extracellular vesicles (CT-EVs) remarkably reduced blood glucose levels and improved insulin sensitivity in T2DM mice. This treatment enhanced glucose metabolism, systemic insulin sensitivity, and insulin secretion function while promoting glycogen accumulation in the liver and muscle. Additionally, CT-EVs treatment protected against the streptozocin (STZ)-induced destruction of islets in T2DM mice by inhibiting β-cell apoptosis. CT-EVs also shielded islets from destruction and increased the expression of p-IRS1 and p-AKT in adipocytes and hepatocytes. In vitro experiments further confirmed its pro-insulin sensitivity effect.

Conclusion

Our data indicate that cold exposure may have a potentially beneficial effect on the development of T2DM, mainly through the anti-diabetic effect of plasma-derived EVs released during cold stimulation. This phenomenon could significantly contribute to understanding the lower prevalence of diabetes in colder regions.

The Advantages and Shortcomings of Stem Cell Therapy for Enhanced Bone Healing

This review explores the regenerative potential of key progenitor cell types and therapeutic strategies to improve healing of complex fractures and bone defects. We define, summarize, and discuss the differentiation potential of totipotent, pluripotent, and multipotent stem cells, emphasizing the advantages and shortcomings of cell therapy for bone repair and regeneration. The fundamental role of mesenchymal stem cells is highlighted due to their multipotency to differentiate into the key lineage cells including osteoblasts, osteocytes, and chondrocytes, which are crucial for bone formation and remodeling. Hematopoietic stem cells (HSCs) also play a significant role; immune cells such as macrophages and T-cells modulate inflammation and tissue repair. Osteoclasts are multinucleated cells that are important to bone remodeling. Vascular progenitor (VP) cells are critical to oxygen and nutrient supply. The dynamic interplay among these lineages and their microenvironment is essential for effective bone restoration. Therapies involving cells that are more than "minimally manipulated" are controversial and include embryonic stem cells (ESCs) and induced pluripotent stem cells (iPSCs). ESCs, derived from early-stage embryos, possess pluripotent capabilities and have shown promise in preclinical studies for bone healing. iPSCs, reprogrammed from somatic cells, offer personalized medicine applications and can differentiate into various tissue-specific cell lines. Minimally manipulative cell therapy approaches such as the use of bone marrow aspirate concentrate (BMAC), exosomes, and various biomaterials for local delivery are explored for their effectiveness in bone regeneration. BMAC, which contains mostly immune cells but few mesenchymal and VPs, probably improves bone healing by facilitating paracrine-mediated intercellular communication. Exosome isolation harnesses the biological signals and cellular by-products that are a primary source for cell crosstalk and activation. Safe, efficacious, and cost-effective strategies to enhance bone healing using novel cellular therapies are part of a changing paradigm to modulate the inflammatory, repair, and regenerative pathways to achieve earlier more robust tissue healing and improved physical function. Impact Statement Stem cell therapy holds immense potential for bone healing due to its ability to regenerate damaged tissue. Nonmanipulated bone marrow aspirate contains mesenchymal stem cells that promote bone repair and reduce healing time. Induced pluripotent stem cells offer the advantage of creating patient-specific cells that can differentiate into osteoblasts, aiding in bone regeneration. Other delivery methods, such as scaffold-based techniques, enhance stem cell integration and function. Collectively, these approaches can improve treatment outcomes, reduce recovery periods, and advance our understanding of bone healing mechanisms, making them pivotal in orthopedic research and regenerative medicine.

MicroRNAs in diabetic macroangiopathy

Diabetic macroangiopathy is a leading cause of diabetes-related mortality worldwide. Both genetic and environmental factors, through a multitude of underlying molecular mechanisms, contribute to the pathogenesis of diabetic macroangiopathy. MicroRNAs (miRNAs), a class of non-coding RNAs known for their functional diversity and expression specificity, are increasingly recognized for their roles in the initiation and progression of diabetes and diabetic macroangiopathy. In this review, we will describe the biogenesis of miRNAs, and summarize their functions in diabetic macroangiopathy, including atherosclerosis, peripheral artery disease, coronary artery disease, and cerebrovascular disease, which are anticipated to provide new insights into future perspectives of miRNAs in basic, translational and clinical research, ultimately advancing the diagnosis, prevention, and treatment of diabetic macroangiopathy.

Melatonin alleviates hyperoxia-induced lung injury through elevating MSC exosomal miR-18a-5p expression to repress PUM2 signaling

Mesenchymal stem cells (MSC)-derived exosomes (Exo) are a possible option for hyperoxia-induced lung injury (HLI). We wanted to see if melatonin (MT)-pretreated MSC-derived exosomes (MT-Exo) were more effective against HLI, and we also tried to figure out the underlying mechanism. HLI models were established by hyperoxia exposure. HE staining was adopted to analyze lung pathological changes. MTT and flow cytometry were used to determine cell viability and apoptosis, respectively. The mitochondrial membrane potential (MMP) was analyzed using the JC-1 probe. LDH, ROS, SOD, and GSH-Px levels were examined by the corresponding kits. The interactions between miR-18a-5p, PUM2, and DUB3 were analyzed by molecular interaction experiments. MT-Exo could effectively inhibit hyperoxia-induced oxidative stress, inflammatory injury, and apoptosis in lung epithelial cells, while these effects of MT-Exo were weakened by miR-18a-5p knockdown in MSCs. miR-18a-5p reduced PUM2 expression in MLE-12 cells by directly targeting PUM2. In addition, PUM2 inactivated the Nrf2/HO-1 signaling pathway by promoting DUB3 mRNA decay post-transcriptionally. As expected, PUM2 overexpression or DUB3 knockdown abolished the protective effect of MT-Exo on hyperoxia-induced lung epithelial cell injury. MT-Exo carrying miR-18a-5p reduced hyperoxia-mediated lung injury in mice through activating Nrf2/HO-1 pathway. MT reduced PUM2 expression and subsequently activated the DUB3/Nrf2/HO-1 signal axis by increasing miR-18a-5p expression in MSC-derived exosomes to alleviate HLI.

Sodium Tanshinone IIA Sulfonate alleviates vascular senescence in diabetic mice by modulating the A20-NFκB-NLRP3 inflammasome-catalase pathway

Diabetes accelerates vascular senescence, which is the basis for atherosclerosis and stiffness. The activation of NOD-like receptor family pyrin domain containing 3 (NLRP3) inflammasome and oxidative stress are closely associated with the deteriorative senescence in endothelial cells (ECs) and vascular smooth muscle cells (VSMCs). For decades, Sodium Tanshinone IIA Sulfonate (STS) has been utilized as a cardiovascular medicine with acknowledged anti-inflammatory and anti-oxidative properties. Nevertheless, the impact of STS on vascular senescence remains unexplored in diabetes. Diabetic mice, primary ECs and VSMCs were transfected with the NLRP3 overexpression/knockout plasmid, the tumor necrosis factor alpha-induced protein 3 (TNFAIP3/A20) overexpression/knockout plasmid, and treated with STS to detect senescence-associated markers. In diabetic mice, STS treatment maintained catalase (CAT) level and vascular relaxation, reduced hydrogen peroxide probe (ROSgreen) fluorescence, p21 immunofluorescence, Senescence β-Galactosidase Staining (SA-β-gal) staining area, and collagen deposition in aortas. Mechanistically, STS inhibited NLRP3 phosphorylation (serine 194), NLRP3 dimer formation, NLRP3 expression, and NLRP3-PYCARD (ASC) colocalization. It also suppressed the phosphorylation of IkappaB alpha (IκBα) and NFκB, preserved A20 and CAT levels, reduced ROSgreen density, and decreased the expression of p21 and SA-β-gal staining in ECs and VSMCs under HG culture. Our findings indicate that STS mitigates vascular senescence by modulating the A20-NFκB-NLRP3 inflammasome-CAT pathway in hyperglycemia conditions, offering novel insights into NLRP3 inflammasome activation and ECs and VSMCs senescence under HG culture. This study highlights the potential mechanism of STS in alleviating senescence in diabetic blood vessels, and provides essential evidence for its future clinical application.

Exosomes based strategies for cardiovascular diseases: Opportunities and challenges

Exosomes, as nanoscale extracellular vesicles (EVs), are secreted by all types of cells to facilitate intercellular communication in living organisms. After being taken up by neighboring or distant cells, exosomes can alter the expression levels of target genes in recipient cells and thereby affect their pathophysiological outcomes depending on payloads encapsulated therein. The functions and mechanisms of exosomes in cardiovascular diseases have attracted much attention in recent years and are thought to have cardioprotective and regenerative potential. This review summarizes the biogenesis and molecular contents of exosomes and details the roles played by exosomes released from various cells in the progression and recovery of cardiovascular disease. The review also discusses the current status of traditional exosomes in cardiovascular tissue engineering and regenerative medicine, pointing out several limitations in their application. It emphasizes that some of the existing emerging industrial or bioengineering technologies are promising to compensate for these shortcomings, and the combined application of exosomes and biomaterials provides an opportunity for mutual enhancement of their performance. The integration of exosome-based cell-free diagnostic and therapeutic options will contribute to the further development of cardiovascular regenerative medicine.

Exosomal HMGB3 released by glioma cells confers the activation of NLRP3 inflammasome and pyroptosis in tumor-associated macrophages

BACKGROUND

Previous evidences has highlighted the pivotal role of NOD-like receptor family pyrin domain-containing 3 (NLRP3)-mediated inflammasomes and pyroptosis activation in driving tumor malignancy and shaping the tumor microenvironment. Herein, we aimed to elucidate the impact of high-mobility group box 3 (HMGB3) released in glioma-derived exosomes on macrophage infiltration in gliomas, NLRP3 inflammasome activation and polarization.

METHODS

Transcripts and protein levels of HMGB3, and cytokines associated with macrophage phenotypes and pyroptosis were assessed in glioma tissues and cell lines (U251, LN229, T98G, A172) using qRT-PCR and/or Western blot analysis. Exosomes secreted from LN229 and NHA cells were isolated via differential ultracentrifugation and characterized by transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and analysis of exosome-related markers. PKH67 staining was employed to examine exosomes uptake by THP-1 differentiated macrophages. Flow cytometry was utilized to assess macrophage pyroptotic rates and polarization-related markers.

RESULTS

HMGB3 expression was elevated in glioma tissues, serum samples and tumor cell lines. Kaplan-Meier curves revealed a positive correlation between higher HMGB3 expression and poor overall survival and recurrence-free survival. Moreover, glioma tissues with increased HMGB3 expression exhibited significant upregulation of M2 macrophages markers (CD68, CD206, Arg1) and NLRP3 inflammasome components (NLRP3, IL-1β, ASC), suggesting that HMGB3 was closely associated with macrophage infiltration and NLRP3 inflammasome activation. Notably, HMGB3 was found to be enriched in glioma cell- secreted exosomes and could be internalized by macrophages. Knockdown of HMGB3 in glioma cell exosomes could restrain M2 macrophage polarization, NLRP3 inflammasome activation and pyroptosis.

CONCLUSION

These findings suggested that glioma cells secreted exosomal HMGB3 could facilitate macrophage M2 polarization, pyroptosis and inflammatory infiltration, indicating HMGB3 might be a poor prognosis factor for glioma.

Intracranial calcifications associated with factors related and unrelated to atherosclerosis in older people: A community dwelling cohort study

The cause of intracranial calcification is not fully understood. The aim of the current study was to identify factors associated with intracranial calcification and to determine whether these factors differ in calcification of different sites. A total of 404 community-dwelling people aged 65 or older were included in the study. All subjects underwent brain computed tomography (CT), blood tests, and a Mini-Mental State Examination (MMSE). Intracranial calcifications were scored using CT. Stepwise regression analysis was performed to examine factors associated with intracranial calcification, with each calcification score used as a dependent variable. Independent variables included age, gender, hemoglobin A1c (HbA1c), dyslipidemia, estimated glomerular filtration rate (eGFR), blood pressure, body mass index (BMI), smoking, serum iron, ferritin, and intact parathyroid hormone (PTH). Stepwise regression analysis detected male gender as a predictor of pineal gland calcification and intact PTH as a predictor of basal ganglia calcification. Age and lifestyle diseases were identified as predictors of calcification of the falx cerebri, internal carotid arteries, and vertebral arteries. These results indicate that the mechanisms of calcifications of the pineal gland and basal ganglia might differ from that of artery calcification, and that causes of intracranial calcification might be classified using factors that are and are not related to atherosclerosis.

FTO Stabilizes MIS12 to Inhibit Vascular Smooth Muscle Cell Senescence in Atherosclerotic Plaque

Purpose

Atherosclerosis is the main cause of atherosclerotic cardiovascular disease (CVD). Here, we aimed to uncover the role and mechanisms of fat mass and obesity-associated genes (FTO) in the regulation of vascular smooth muscle cell (VSMC) senescence in atherosclerotic plaques.

Methods

ApoE-/- mice fed a high-fat diet (HFD) were used to establish an atherosclerotic animal model. Immunohistochemistry, and the staining of hematoxylin-eosin, Oil Red O, Sirius red, and Masson were performed to confirm the role of FTO in atherosclerosis in vivo. Subsequently, FTO expression in primary VSMCs is either upregulated or downregulated. Oxidized low-density lipoprotein (ox-LDL) was used to treat VSMCs, followed by EdU staining, flow cytometry, senescence-associated β-galactosidase (SA-β-gal) staining, immunofluorescence, telomere detection, RT-qPCR, and Western blotting to determine the molecular mechanisms by which FTO inhibits VSMC senescence.

Results

Decreased FTO expression was observed in progressive atherosclerotic plaques of ApoE-/- mice fed with HFD. FTO upregulation inhibits atherosclerotic lesions in mice. FTO inhibits VSMC aging in atherosclerotic plaques by helping VSMC withstand ox-LDL-induced cell cycle arrest and senescence. This process is achieved by stabilizing the MIS12 protein in VSMC through a proteasome-mediated pathway.

Conclusion

FTO inhibits VSMC senescence and subsequently slows the progression of atherosclerotic plaques by stabilizing the MIS12 protein.

Heterotopic mineralization (ossification or calcification) in aged musculoskeletal soft tissues: A new candidate marker for aging

Aging can lead to various disorders in organisms and with the escalating impact of population aging, the incidence of age-related diseases is steadily increasing. As a major risk factor for chronic illnesses in humans, the prevention and postponement of aging have become focal points of research among numerous scientists. Aging biomarkers, which mirror molecular alterations at diverse levels in organs, tissues, and cells, can be used to monitor and evaluate biological changes associated with aging. Currently, aging biomarkers are primarily categorized into physiological traits, imaging characteristics, histological features, cellular-level alterations, and molecular-level changes that encompass the secretion of aging-related factors. However, in the context of the musculoskeletal soft tissue system, aging-related biological indicators primarily involve microscopic parameters at the cellular and molecular levels, resulting in inconvenience and uncertainty in the assessment of musculoskeletal soft tissue aging. To identify convenient and effective indicators, we conducted a comprehensive literature review to investigate the correlation between ectopic mineralization and age-related changes in the musculoskeletal soft tissue system. Here, we introduce the concept of ectopic mineralization as a macroscopic, reliable, and convenient biomarker for musculoskeletal soft tissue aging and present novel targets and strategies for the future management of age-related musculoskeletal soft tissue disorders.

New Perspectives on the Role and Therapeutic Potential of Melatonin in Cardiovascular Diseases

Cardiovascular diseases (CVDs) are the leading cause of death and disability worldwide. It is essential to develop novel interventions to prevent/delay CVDs by targeting their fundamental cellular and molecular processes. Melatonin is a small indole molecule acting both as a hormone of the pineal gland and as a local regulator molecule in various tissues. It has multiple features that may contribute to its cardiovascular protection. Moreover, melatonin enters all cells and subcellular compartments and crosses morphophysiological barriers. Additionally, this indoleamine also serves as a safe exogenous therapeutic agent. Increasing evidence has demonstrated the beneficial effects of melatonin in preventing and improving cardiovascular risk factors. Exogenous administration of melatonin, as a result of its antioxidant and anti-inflammatory properties, has been reported to decrease blood pressure, protect against atherosclerosis, attenuate molecular and cellular damage resulting from cardiac ischemia/reperfusion, and improve the prognosis of myocardial infarction and heart failure. This review aims to summarize the beneficial effects of melatonin against these conditions, the possible protective mechanisms of melatonin, and its potential clinical applicability in CVDs.

Mitochondrial Melatonin: Beneficial Effects in Protecting against Heart Failure

Cardiovascular disease is the cause of physical infirmity and thousands of deaths annually. Typically, during heart failure, cardiomyocyte mitochondria falter in terms of energy production and metabolic processing. Additionally, inflammation and the accumulation of non-contractile fibrous tissue contribute to cardiac malfunction. Melatonin, an endogenously produced molecule, experimentally reduces the initiation and progression of atherosclerotic lesions, which are often the basis of coronary artery disease. The current review critically analyzes published data related to the experimental use of melatonin to forestall coronary artery pathologies. Collectively, these studies document melatonin's anti-atherosclerotic actions in reducing LDL oxidation and triglyceride levels, lowering endothelial malfunction, limiting adhesion molecule formation, preventing macrophage polarization to the M1 pro-inflammatory phenotype, changing cellular metabolism, scavenging destructive reactive oxygen species, preventing the proliferation and invasion of arterial smooth muscle cells into the lesioned area, restricting the ingrowth of blood vessels from the vasa vasorum, and solidifying the plaque cap to reduce the chance of its rupture. Diabetic hyperglycemia, which aggravates atherosclerotic plaque formation, is also inhibited by melatonin supplementation in experimental animals. The potential value of non-toxic melatonin as a possible inhibitor of cardiac pathology in humans should be seriously considered by performing clinical trials using this multifunctional molecule.

What role do extracellular vesicles play in developing physical frailty and sarcopenia? : A systematic review

BACKGROUND

Frailty and sarcopenia are typical geriatric conditions with a complex pathophysiology. Extracellular vesicles (EVs) are key regulators of age-related diseases, but the mechanisms underlying physical frailty, sarcopenia, and EVs are not well understood.

METHODS

A systematic literature review was conducted to examine the evidence supporting an association between EVs and physical frailty and/or sarcopenia by searching the electronic databases, including the Cochrane Library, PubMed, and Embase, from January 2000 to January 2021.

RESULTS

A total of 216 cross-sectional studies were retrieved, and after the removal of 43 duplicate records, the title and abstract of 167 articles were screened, identifying 6 relevant articles for full-text review. Of the studies five met the inclusion criteria, and heterogeneity among studies was high. There is controversy regarding whether frailty and/or sarcopenia are related to circulating EV levels; however, the cargo of EVs has been associated with frailty and sarcopenia in various ways, such as microRNAs, mitochondrial-derived vesicles (MDVs), and protein cargoes.

CONCLUSION

Recent studies, although limited, depicted that EVs could be one of the underlying mechanisms of frailty and/or sarcopenia. There is a possibility that physical frailty and sarcopenia may have specific EV concentrations and cargo profiles; however, further research is required to fully understand the mechanisms and identify potential biomarkers and early preventative strategies for physical frailty and sarcopenia.

Vascular calcification: from the perspective of crosstalk

Vascular calcification (VC) is highly correlated with cardiovascular disease morbidity and mortality, but anti-VC treatment remains an area to be tackled due to the ill-defined molecular mechanisms. Regardless of the type of VC, it does not depend on a single cell but involves multi-cells/organs to form a complex cellular communication network through the vascular microenvironment to participate in the occurrence and development of VC. Therefore, focusing only on the direct effect of pathological factors on vascular smooth muscle cells (VSMCs) tends to overlook the combined effect of other cells and VSMCs, including VSMCs-VSMCs, ECs-VMSCs, Macrophages-VSMCs, etc. Extracellular vesicles (EVs) are a collective term for tiny vesicles with a membrane structure that are actively secreted by cells, and almost all cells secrete EVs. EVs docked on the surface of receptor cells can directly mediate signal transduction or transfer their contents into the cell to elicit a functional response from the receptor cells. They have been proven to participate in the VC process and have also shown attractive therapeutic prospects. Based on the advantages of EVs and the ability to be detected in body fluids, they may become a novel therapeutic agent, drug delivery vehicle, diagnostic and prognostic biomarker, and potential therapeutic target in the future. This review focuses on the new insight into VC molecular mechanisms from the perspective of crosstalk, summarizes how multi-cells/organs interactions communicate via EVs to regulate VC and the emerging potential of EVs as therapeutic methods in VC. We also summarize preclinical experiments on crosstalk-based and the current state of clinical studies on VC-related measures.

Melatonin ameliorates atherosclerosis by suppressing S100a9-mediated vascular inflammation

Atherosclerosis (AS)-associated cardiovascular diseases are predominant causes of morbidity and mortality worldwide. Melatonin, a circadian hormone with anti-inflammatory activity, may be a novel therapeutic intervention for AS. However, the exact mechanism is unclear. This research intended to investigate the mechanism of melatonin in treating AS. Melatonin (20 mg/kg/d) was intraperitoneally administered in a high-fat diet (HFD)-induced AS model using apolipoprotein E-deficient (ApoE-/-) mice for 12 weeks. Immunohistochemical and immunofluorescence analyses, data-independent acquisition (DIA)-based protein profiling, ingenuity pathway analysis (IPA), and western blotting were employed to investigate the therapeutic effects of melatonin in treating HFD-induced AS. An adeno-associated virus (AAV) vector was further used to confirm the antiatherosclerotic mechanism of melatonin. Melatonin treatment markedly attenuated atherosclerotic lesions, induced stable phenotypic sclerotic plaques, inhibited macrophage infiltration, and suppressed the production of proinflammatory cytokines in ApoE-/- mice with HFD-induced AS. Notably, DIA-based quantitative proteomics together with IPA identified S100a9 as a pivotal mediator in the protective effects of melatonin. Moreover, melatonin significantly suppressed HFD-induced S100a9 expression at both the mRNA and protein levels. The overexpression of S100a9 significantly activated the NF-κB signaling pathway and markedly abolished the antagonistic effect of melatonin on HFD-induced vascular inflammation during atherogenesis. Melatonin exerts a significant antiatherogenic effect by inhibiting S100a9/NF-κB signaling pathway-mediated vascular inflammation. Our findings reveal a novel antiatherosclerotic mechanism of melatonin and underlie its potential clinical use in modulating AS with good availability and affordability.

Exosomal miR-129 and miR-342 derived from intermittent hypoxia-stimulated vascular smooth muscle cells inhibit the eIF2α/ATF4 axis from preventing calcified aortic valvular disease

This study aims to elucidate the role of miR-129/miR-342 loaded in exosomes derived from vascular smooth muscle cells (VSMCs) stimulated by intermittent hypoxia in calcified aortic valvular disease (CAVD). Bioinformatics analysis was conducted to identify differentially expressed miRs in VSMCs-derived exosomes and CAVD samples, and their potential target genes were predicted. VSMCs were exposed to intermittent hypoxia to induce stimulation, followed by isolation of exosomes. Valvular interstitial cells (VICs) were cultured in vitro to investigate the impact of miR-129/miR-342 on VICs' osteogenic differentiation and aortic valve calcification with eIF2α. A CAVD mouse model was established using ApoE knockout mice for in vivo validation. In CAVD samples, miR-129 and miR-342 were downregulated, while eIF2α and ATF4 were upregulated. miR-129 and miR-342 exhibited inhibitory effects on eIF2α through targeted regulation. Exosomes released from intermittently hypoxia-stimulated VSMCs contained miR-129 and miR-342. Overexpression of miR-129 and miR-342, or silencing ATF4, suppressed VICs' osteogenic differentiation and aortic valve calcification, which could be rescued by overexpressed eIF2α. Collectively, intermittent hypoxia stimulation of VSMCs leads to the secretion of exosomes that activate the miR-129/miR-342 dual pathway, thereby inhibiting the eIF2α/ATF4 axis and attenuating VICs' osteogenic differentiation and CAVD progression.

Exosomes as cutting-edge therapeutics in various biomedical applications: An update on engineering, delivery, and preclinical studies

Exosomes are cell-derived nanovesicles, circulating in different body fluids, and acting as an intercellular mechanism. They can be purified from culture media of different cell types and carry an enriched content of various protein and nucleic acid molecules originating from their parental cells. It was indicated that the exosomal cargo can mediate immune responses via many signaling pathways. Over recent years, the therapeutic effects of various exosome types were broadly investigated in many preclinical studies. Herein, we present an update on recent preclinical studies on exosomes as therapeutic and/or delivery agents for various applications. The exosome origin, structural modifications, natural or loaded active ingredients, size, and research outcomes were summarized for various diseases. Overall, the present article provides an overview of the latest exosome research interests and developments to clear the way for the clinical study design and application.

Vascular wall microenvironment: exosomes secreted by adventitial fibroblasts induced vascular calcification

Vascular calcification often occurs in patients with chronic renal failure (CRF), which significantly increases the incidence of cardiovascular events in CRF patients. Our previous studies identified the crosstalk between the endothelial cells (ECs) and vascular smooth muscle cells (VSMCs), and the paracrine effect of VSMCs, which regulate the calcification of VSMCs. Herein, we aim to investigate the effects of exosomes secreted by high phosphorus (HPi) -induced adventitial fibroblasts (AFs) on the calcification of VSMCs and the underlying mechanism, which will further elucidate the important role of AFs in high phosphorus vascular wall microenvironment. The conditioned medium of HPi-induced AFs promotes the calcification of VSMCs, which is partially abrogated by GW4869, a blocker of exosomes biogenesis or release. Exosomes secreted by high phosphorus-induced AFs (AFsHPi-Exos) show similar effects on VSMCs. miR-21-5p is enriched in AFsHPi-Exos, and miR-21-5p enhances osteoblast-like differentiation of VSMCs by downregulating cysteine-rich motor neuron 1 (Crim1) expression. AFsHPi-Exos and exosomes secreted by AFs with overexpression of miR-21-5p (AFsmiR21M-Exos) significantly accelerate vascular calcification in CRF mice. In general, AFsHPi-Exos promote the calcification of VSMCs and vascular calcification by delivering miR-21-5p to VSMCs and subsequently inhibiting the expression of Crim1. Combined with our previous studies, the present experiment supports the theory of vascular wall microenvironment.

Cold exposure protects against medial arterial calcification development via autophagy

Medial arterial calcification (MAC), a systemic vascular disease different from atherosclerosis, is associated with an increased incidence of cardiovascular events. Several studies have demonstrated that ambient temperature is one of the most important factors affecting cardiovascular events. However, there has been limited research on the effect of different ambient temperatures on MAC. In the present study, we showed that cold temperature exposure (CT) in mice slowed down the formation of vitamin D (VD)-induced vascular calcification compared with room temperature exposure (RT). To investigate the mechanism involved, we isolated plasma-derived exosomes from mice subjected to CT or RT for 30 days (CT-Exo or RT-Exo, respectively). Compared with RT-Exo, CT-Exo remarkably alleviated the calcification/senescence formation of vascular smooth muscle cells (VSMCs) and promoted autophagy by activating the phosphorylation of AMP-activated protein kinase (p-AMPK) and inhibiting phosphorylation of mammalian target of rapamycin (p-mTOR). At the same time, CT-Exo promoted autophagy in β-glycerophosphate (β-GP)-induced VSMCs. The number of autophagosomes and the expression of autophagy-related proteins ATG5 and LC3B increased, while the expression of p62 decreased. Based on a microRNA chip microarray assay and real-time polymerase chain reaction, miR-320a-3p was highly enriched in CT-Exo as well as thoracic aortic vessels in CT mice. miR-320a-3p downregulation in CT-Exo using AntagomiR-320a-3p inhibited autophagy and blunted its anti-calcification protective effect on VSMCs. Moreover, we identified that programmed cell death 4 (PDCD4) is a target of miR-320a-3p, and silencing PDCD4 increased autophagy and decreased calcification in VSMCs. Treatment with CT-Exo alleviated the formation of MAC in VD-treated mice, while these effects were partially reversed by GW4869. Furthermore, the anti-arterial calcification protective effects of CT-Exo were largely abolished by AntagomiR-320a-3p in VD-induced mice. In summary, we have highlighted that prolonged cold may be a good way to reduce the incidence of MAC. Specifically, miR-320a-3p from CT-Exo could protect against the initiation and progression of MAC via the AMPK/mTOR autophagy pathway.

Vascular Ageing: Mechanisms, Risk Factors, and Treatment Strategies

Ageing constitutes the biggest risk factor for poor health and adversely affects the integrity and function of all the cells, tissues, and organs in the human body. Vascular ageing, characterised by vascular stiffness, endothelial dysfunction, increased oxidative stress, chronic low-grade inflammation, and early-stage atherosclerosis, may trigger or exacerbate the development of age-related vascular diseases, which each year contribute to more than 3.8 million deaths in Europe alone and necessitate a better understanding of the mechanisms involved. To this end, a large number of recent preclinical and clinical studies have focused on the exponential accumulation of senescent cells in the vascular system and paid particular attention to the specific roles of senescence-associated secretory phenotype, proteostasis dysfunction, age-mediated modulation of certain microRNA (miRNAs), and the contribution of other major vascular risk factors, notably diabetes, hypertension, or smoking, to vascular ageing in the elderly. The data generated paved the way for the development of various senotherapeutic interventions, ranging from the application of synthetic or natural senolytics and senomorphics to attempt to modify lifestyle, control diet, and restrict calorie intake. However, specific guidelines, considering the severity and characteristics of vascular ageing, need to be established before widespread use of these agents. This review briefly discusses the molecular and cellular mechanisms of vascular ageing and summarises the efficacy of widely studied senotherapeutics in the context of vascular ageing.

Extracellular vesicles in atherosclerosis and vascular calcification: the versatile non-coding RNAs from endothelial cells and vascular smooth muscle cells

Atherosclerosis (AS) is characterized by the accumulation of lipids, fibrous elements, and calcification in the innermost layers of arteries. Vascular calcification (VC), the deposition of calcium and phosphate within the arterial wall, is an important characteristic of AS natural history. However, medial arterial calcification (MAC) differs from intimal calcification and cannot simply be explained as the consequence of AS. Endothelial cells (ECs) and vascular smooth muscle cells (VSMCs) are directly involved in AS and VC processes. Understanding the communication between ECs and VSMCs is critical in revealing mechanisms underlying AS and VC. Extracellular vesicles (EVs) are found as intercellular messengers in kinds of physiological processes and pathological progression. Non-coding RNAs (ncRNAs) encapsulated in EVs are involved in AS and VC, including microRNAs (miRNAs), long non-coding RNAs (lncRNAs), and circular RNAs (circRNAs). The effects of ncRNAs have not been comprehensively understood, especially encapsulated in EVs. Some ncRNAs have demonstrated significant roles in AS and VC, but it remains unclear the functions of the majority ncRNAs detected in EVs. In this review, we summarize ncRNAs encapsulated in EC-EVs and VSMC-EVs, and the signaling pathways that are involved in AS and VC.

MicroRNA regulation of phenotypic transformations in vascular smooth muscle: relevance to vascular remodeling

Alterations in the vascular smooth muscle cells (VSMC) phenotype play a critical role in the pathogenesis of several cardiovascular diseases, including hypertension, atherosclerosis, and restenosis after angioplasty. MicroRNAs (miRNAs) are a class of endogenous noncoding RNAs (approximately 19-25 nucleotides in length) that function as regulators in various physiological and pathophysiological events. Recent studies have suggested that aberrant miRNAs' expression might underlie VSMC phenotypic transformation, appearing to regulate the phenotypic transformations of VSMCs by targeting specific genes that either participate in the maintenance of the contractile phenotype or contribute to the transformation to alternate phenotypes, and affecting atherosclerosis, hypertension, and coronary artery disease by altering VSMC proliferation, migration, differentiation, inflammation, calcification, oxidative stress, and apoptosis, suggesting an important regulatory role in vascular remodeling for maintaining vascular homeostasis. This review outlines recent progress in the discovery of miRNAs and elucidation of their mechanisms of action and functions in VSMC phenotypic regulation. Importantly, as the literature supports roles for miRNAs in modulating vascular remodeling and for maintaining vascular homeostasis, this area of research will likely provide new insights into clinical diagnosis and prognosis and ultimately facilitate the identification of novel therapeutic targets.

MicroRNA-19b-3p dysfunction of mesenchymal stem cell-derived exosomes from patients with abdominal aortic aneurysm impairs therapeutic efficacy

Senescence of vascular smooth muscle cells (VSMCs) contributes to the formation of abdominal aortic aneurysm (AAA). Although mesenchymal stem cell exosomes (MSC-EXO) have been confirmed to restrict the development of AAA, their biological activity depends largely on the physiological state of the MSCs. This study aimed to compare the effects of adipose-derived MSC-EXO from healthy donors (HMEXO) and AAA patients (AMEXO) on senescence of VSMCs in AAA and explore the underlying mechanisms. An ApoE-/- mouse model of AAA was used to investigate the therapeutic effects of HMEXO, AMEXO or miR-19b-3p-AMEXO on AAA development. This in vitro model of AAA was established by treating VSMCs with Ang II (Angiotensin II). The senescence of VSMCs was determined by senescence-associated β-galactosidase (SA-β-gal) staining. The morphology of mitochondria in VSMCs was examined by MitoTracker staining. HMEXO exhibited superior capacity compared with AMEXO to inhibit VSMC senescence and attenuate AAA formation in Ang II-treated ApoE-/- mice. In vitro, both AMEXO and HMEXO inhibited Ang II-induced VSMC senescence via downregulation of mitochondrial fission. Notably, compared with HMEXO, the ability of AMEXO to inhibit VSMC senescence was significantly decreased. miRNA sequencing and the expression of miR-19b-3p was significantly decreased in AMEXO compared with HMEXO. Luciferase assay suggested that MST4 (Mammalian sterile-20-like kinase 4) is a potential target of miR-19b-3p. Mechanistically, miR-19b-3p in HMEXO ameliorated VSMC senescence by inhibiting mitochondrial fission via regulation of the MST4/ERK/Drp1 signaling pathway. Overexpression of miR-19b-3p in AMEXO improved their beneficial effect on AAA formation. Our study reveals that MSC-exosomal miR-19b-3p exerts protective effects against Ang II-induced AAA and VSMC senescence via regulation of the MST4/ERK/Drp1 pathway. The pathological state of AAA patients alters the miRNA components of AMEXO and impairs their therapeutic benefits.

Plasma exosome miRNA-26b-3p derived from idiopathic short stature impairs longitudinal bone growth via the AKAP2/ERK1/2 axis

BACKGROUND

Currently, the etiology of idiopathic short stature (ISS) is still unclear. The poor understanding of the molecular mechanisms of ISS has largely restricted this strategy towards safe and effective clinical therapies.

METHODS

The plasma exosomes of ISS children were co-cultured with normal human chondrocytes. The differential expression of exosome miRNA between ISS and normal children was identified via high-throughput microRNA sequencing and bioinformatics analysis. Immunohistochemistry, In situ hybridization, RT-qPCR, western blotting, luciferase expression, and gene overexpression and knockdown were performed to reveal the key signaling pathways that exosome miRNA of aberrant expression in ISS children impairs longitudinal bone growth.

RESULTS

Chondrocytes proliferation and endochondral ossification were suppressed after coculture of ISS plasma exosomes with human normal chondrocytes. High-throughput microRNA sequencing and RT-qPCR confirmed that plasma exosome miR-26b-3p was upregulated in ISS children. Meanwhile, exosome miRNA-26b-3p showed a high specificity and sensitivity in discriminating ISS from normal children. The rescue experiment showed that downregulation of miR-26b-3p obviously improved the repression of chondrocyte proliferation and endochondral ossification caused by ISS exosomes. Subsequently, miR-26b-3p overexpression inhibited chondrocyte proliferation and endochondral ossification once again. In situ hybridization confirmed the colocalization of miR-26b-3p with AKAP2 in chondrocytes. In vitro and in vivo assay revealed exosome miRNA-26b-3p impairs longitudinal bone growth via the AKAP2 /ERK1/2 axis.

CONCLUSIONS

This study is the first to confirm that miR-26b-3p overexpression in ISS plasma exosomes leads to disorders in proliferation and endochondral ossification of growth plate cartilage via inhibition of AKAP2/ERK1/2 axis, thereby inducing ISS. This study provides a new research direction for the etiology and pathology of ISS and a new idea for the biological treatment of ISS.

Emerging role of exosomes in vascular diseases

Exosomes are biological small spherical lipid bilayer vesicles secreted by most cells in the body. Their contents include nucleic acids, proteins, and lipids. Exosomes can transfer material molecules between cells and consequently have a variety of biological functions, participating in disease development while exhibiting potential value as biomarkers and therapeutics. Growing evidence suggests that exosomes are vital mediators of vascular remodeling. Endothelial cells (ECs), vascular smooth muscle cells (VSMCs), inflammatory cells, and adventitial fibroblasts (AFs) can communicate through exosomes; such communication is associated with inflammatory responses, cell migration and proliferation, and cell metabolism, leading to changes in vascular function and structure. Essential hypertension (EH), atherosclerosis (AS), and pulmonary arterial hypertension (PAH) are the most common vascular diseases and are associated with significant vascular remodeling. This paper reviews the latest research progress on the involvement of exosomes in vascular remodeling through intercellular information exchange and provides new ideas for understanding related diseases.

BMF-AS1/BMF Promotes Diabetic Vascular Calcification and Aging both In Vitro and In Vivo

Vascular calcification and aging often increase morbidity and mortality in patients with diabetes mellitus (DM); however, the underlying mechanisms are still unknown. In the present study, we found that Bcl-2 modifying factor (BMF) and BMF antisense RNA 1 (BMF-AS1) were significantly increased in high glucose-induced calcified and senescent vascular smooth muscle cells (VSMCs) as well as artery tissues from diabetic mice. Inhibition of BMF-AS1 and BMF reduced the calcification and senescence of VSMCs, whereas overexpression of BMF-AS1 and BMF generates the opposite results. Mechanistic analysis showed that BMF-AS1 interacted with BMF directly and up-regulated BMF at both mRNA and protein levels, but BMF did not affect the expression of BMF-AS1. Moreover, knocking down BMF-AS1 and BMF suppressed the calcification and senescence of VSMCs, and BMF knockout (BMF^-/-) diabetic mice presented less vascular calcification and aging compared with wild type diabetic mice. In addition, higher coronary artery calcification scores (CACs) and increased plasma BMF concentration were found in patients with DM, and there was a positive correlation between CACs and plasma BMF concentration. Thus, BMF-AS1/BMF plays a key role in promoting high glucose-induced vascular calcification and aging both in vitro and in vivo. BMF-AS1 and BMF represent potential therapeutic targets in diabetic vascular calcification and aging.

Melatonin: a potential therapeutic approach for the management of primary Sjögren's syndrome

Primary Sjögren's syndrome (pSS) is an autoimmune disease that primarily affects the exocrine glands and is mainly characterized by sicca symptoms of the eyes and mouth. Approximately 30-50% of pSS patients develop systemic multi-organ disorders including malignant lymphoma. The etiology of pSS is not well understood; growing evidence suggests that uncontrolled immune/inflammatory responses, excessive oxidative stress, defected apoptosis, dysregulated autophagy, exosomes, and exogenous virus infections may participate in the pathogenesis of pSS. There is no ideal therapeutic method for pSS; the management of pSS is mainly palliative, which aims to alleviate sicca symptoms. Melatonin, as the main secretory product of the pineal gland, has been evidenced to show various physiological functions, including effects of immunoregulation, capability of antioxidation, moderation of autophagy, suppressive activities of apoptosis, regulative capacity of exosomes, properties of anti-infection, and improvement of sleep. The beneficial effects of melatonin have been already validated in some autoimmune diseases such as multiple sclerosis (MS), type 1 diabetes mellitus (T1DM), systemic lupus erythematosus (SLE), and inflammatory bowel disease (IBD). However, our previous research firstly revealed that melatonin might inhibit pathogenic responses of peripheral Th17 and double-negative (DN) T cells in pSS. More importantly, melatonin administration alleviated the development of pSS in animal models with reduced infiltrating lymphocytes, improved functional activity of salivary gland, and decreased production of inflammatory factors as well as autoantibodies. Owing to the important biological properties reported in melatonin are characteristics closely related to the treatment of pSS; the potential role and underlying mechanisms of melatonin in the administration of pSS are certainly worth further investigations. Consequently, the aim of this review is to give a deep insight to the therapeutic potency of melatonin for pSS.

Vaspin alleviates the lncRNA LEF1-AS1-induced osteogenic differentiation of vascular smooth muscle cells via the Hippo/YAP signaling pathway

Vascular calcification (VC) is closely related to higher cardiovascular mortality and morbidity, and vascular smooth muscle cell (VSMC) switching to osteogenic-like cells is crucial for VC. LncRNA LEF1-AS1 promotes atherosclerosis and dental pulp stem cells calcification, while its role in VC remains unknown. Visceral adipose tissue-derived serine protease inhibitor (vaspin) is an adipokine regulating bone metabolism. However, the relationship between vaspin and VC is still unclear. We aimed to explore the role of LEF1-AS1 on VSMC osteogenic transition, whether vaspin inhibited LEF1-AS1-mediated osteogenic differentiation of VSMCs, and the responsible mechanism. In this study, quantitative real-time polymerase chain reaction (qRT-PCR) and western blotting analysis indicated that LEF1-AS1 overexpression significantly upregulated osteogenic marker Runt-related transcription factor-2 (RUNX2) level and downregulated VSMC contractile marker α-smooth muscle actin (α-SMA) level. Alizarin red staining, alkaline phosphatase (ALP) staining, ALP activity assay, and calcium content assay also suggested that LEF1-AS1 overexpression promoted calcium deposition in VSMCs. However, vaspin treatment abolished this phenomenon. Mechanistically, LEF1-AS1 markedly decreased phosphorylated YAP level, while vaspin reversed LEF1-AS1-induced phosphorylated YAP decline. Our results revealed that LEF1-AS1 accelerated the osteogenic differentiation of VSMCs by regulating the Hippo/YAP pathway, while vaspin eliminated the LEF1-AS1-meditated VSMCs osteogenic phenotype switch.

Exosomes Derived from BMMSCs Mitigate the Hepatic Fibrosis via Anti-Pyroptosis Pathway in a Cirrhosis Model

Researchers increasingly report the therapeutic effect of exosomes derived from rat bone marrow mesenchymal stem cells (Exos-rBMMSC) on liver disease, while the optimal dose of Exos-rBMMSC in liver cirrhotic treatment has not been reported. In this study, we aimed to explore the efficacy and dose of Exos-rBMMSC in a hepatic cirrhosis rat model. The therapeutic effects of a low dose, medium dose and high dose of Exos-rBMMSC were assessed by liver function tests and histopathology. After four-weeks of Exos-rBMMSC therapy, pyroptosis-related expression levels in the medium dose and the high dose Exos-rBMMSC groups were significantly decreased compared to those in the liver cirrhosis group (p < 0.05). The hepatic function assay and histopathology results showed significant improvement in the medium dose and the high dose Exos-rBMMSCs groups. The localization of PKH67-labeled Exos-rBMMSC was verified microscopically, and these particles were coexpressed with the PCNA, NLRP3, GSDMD and Caspase-1. Our results demonstrated that Exos-rBMMSC accelerated hepatocyte proliferation and relieved liver fibrosis by restraining hepatocyte pyroptosis. More importantly, we confirmed that the high dose of Exos-rBMMSC may be the optimal dose for liver cirrhosis, which is conducive to the application of Exos-rBMMSC as a promising cell-free strategy.

The role of extracellular vesicles in vascular calcification in chronic kidney disease

Widespread vascular calcification (VC) in patients with chronic kidney disease (CKD) is the pathological basis for the development of cardiovascular disease, and VC has been identified as an independent risk factor for increased cardiovascular mortality in cases of CKD. While VC was earlier thought to be a passive deposition process following calcium and phosphorus supersaturation, recent studies have suggested that it is an active, modifiable, biological process similar to bone development. The involvement of extracellular vesicles (EVs) in the process of VC has been reported as an important transporter of material transport and intercellular communication. This paper reviews the mechanism of the role of EVs, especially exosomes, in VC and the regulation of VC by stem cell-derived EVs, and discusses the possible and promising application of related therapeutic targets in the clinical setting.

Exosomes: mediators regulating the phenotypic transition of vascular smooth muscle cells in atherosclerosis

Cardiovascular disease is one of the leading causes of human mortality worldwide, mainly due to atherosclerosis (AS), and the phenotypic transition of vascular smooth muscle cells (VSMCs) is a key event in the development of AS. Exosomes contain a variety of specific nucleic acids and proteins that mediate intercellular communication. The role of exosomes in AS has attracted attention. This review uses the VSMC phenotypic transition in AS as the entry point, introduces the effect of exosomes on AS from different perspectives, and discusses the status quo, deficiencies, and potential future directions in this field to provide new ideas for clinical research and treatment of AS. Video Abstract.

Vascular Calcification: In Vitro Models under the Magnifying Glass

Vascular calcification is a systemic disease contributing to cardiovascular morbidity and mortality. The pathophysiology of vascular calcification involves calcium salt deposition by vascular smooth muscle cells that exhibit an osteoblast-like phenotype. Multiple conditions drive the phenotypic switch and calcium deposition in the vascular wall; however, the exact molecular mechanisms and the connection between vascular smooth muscle cells and other cell types are not fully elucidated. In this hazy landscape, effective treatment options are lacking. Due to the pathophysiological complexity, several research models are available to evaluate different aspects of the calcification process. This review gives an overview of the in vitro cell models used so far to study the molecular processes underlying vascular calcification. In addition, relevant natural and synthetic compounds that exerted anticalcifying properties in in vitro systems are discussed.

Melatonin pretreatment on exosomes: Heterogeneity, therapeutic effects, and usage

The therapeutic outcomes of exosome-based therapies have greatly exceeded initial expectations in many clinically intractable diseases due to the safety, low toxicity, and immunogenicity of exosomes, but the production of the exosomes is a bottleneck for wide use. To increase the yield of the exosomes, various solutions have been tried, such as hypoxia, extracellular acidic pH, etc. With a limited number of cells or exosomes, an alternative approach has been developed to improve the efficacy of exosomes through cell pretreatment recently. Melatonin is synthesized from tryptophan and secreted in the pineal gland, presenting a protective effect in pathological conditions. As a new pretreatment method, melatonin can effectively enhance the antioxidant, anti-inflammatory, and anti-apoptotic function of exosomes in chronic kidney disease, diabetic wound healing, and ischemia-reperfusion treatments. However, the current use of melatonin pretreatment varies widely. Here, we discuss the effects of melatonin pretreatment on the heterogeneity of exosomes based on the role of melatonin and further speculate on the possible mechanisms. Finally, the therapeutic use of exosomes and the usage of melatonin pretreatment are described.

Estrogen-dependent depressor response of melatonin via baroreflex afferent function and intensification of PKC-mediated Nav1.9 activation

Recent studies suggest that melatonin (Mel) plays an important role in the regulation of blood pressure (BP) via the aortic baroreflex pathway. In this study, we investigated the interaction between the baroreflex afferent pathway and Mel-mediated BP regulation in rats under physiological and hypertensive conditions. Mel (0.1, 0.3, and 1.0 mg/mL) was microinjected into the nodose ganglia (NG) of rats. We showed that Mel-induced reduction of mean arterial pressure in female rats was significantly greater than that in male and in ovariectomized rats under physiological condition. Consistently, the expression of Mel receptors (MTNRs) in the NG of female rats was significantly higher than that of males. In L-NAME-induced hypertensive and spontaneously hypertensive rat models, MTNRs were upregulated in males but downregulated in female models. Interestingly, Mel-induced BP reduction was found in male hypertensive models. In whole-cell recording from identified baroreceptor neurons (BRNs) in female rats, we found that Mel (0.1 μM) significantly increased the excitability of a female-specific subpopulation of Ah-type BRNs by increasing the Nav1.9 current density via a PKC-mediated pathway. Similar results were observed in baroreceptive neurons of the nucleus tractus solitarius, showing the facilitation of spontaneous and evoked excitatory post-synaptic currents in Ah-type neurons. Collectively, this study reveals the estrogen-dependent effect of Mel/MTNRs under physiological and hypertensive conditions is mainly mediated by Ah-type BRNs, which may provide new theoretical basis and strategies for the gender-specific anti-hypertensive treatment in clinical practice.

Curcumin attenuates vascular calcification via the exosomal miR-92b-3p/KLF4 axis

Vascular calcification (VC) is the most widespread pathological change in diseases of the vascular system. However, we do not have a good understanding of the molecular mechanisms and effective therapeutic approaches for VC. Curcumin (CUR) is a natural polyphenolic compound that has hypolipidemic, anti-inflammatory, and antioxidant effects on the cardiovascular system. Exosomes are known to have extensive miRNAs for intercellular regulation. This study investigated whether CUR attenuates VC by affecting the secretion of exosomal miRNAs. Calcification models were established in vivo and in vitro using vitamin D3 and β-glycerophosphate, respectively. Appropriate therapeutic concentrations of CUR were detected on vascular smooth muscle cells (VSMCs) using a cell counting kit 8. Exosomes were extracted by super speed centrifugation from the supernatant of cultured VSMCs and identified by transmission electron microscopy and particle size analysis. Functional and phenotypic experiments were performed in vitro to verify the effects of CUR and exosomes secreted by VSMCs treated with CUR on calcified VSMCs. Compared with the calcified control group, both CUR and exosomes secreted by VSMCs after CUR intervention attenuated calcification in VSMCs. Real-Time quantitative PCR (RT-qPCR) experiments showed that miR-92b-3p, which is important for alleviating VC, was expressed highly in both VSMCs and exosomes after CUR intervention. The mimic miR-92b-3p significantly decreased the expression of transcription factor KLF4 and osteogenic factor RUNX2 in VSMCs, while the inhibitor miR-92b-3p had the opposite effect. Based on bioinformatics databases and dual luciferase experiments, the prospective target of miR-92b-3p was determined to be KLF4. Both mRNA and protein of RUNX2 were decreased and increased in VSMCs by inhibiting and overexpressing of KLF4, respectively. In addition, in the rat calcification models, CUR attenuated vitamin D3-induced VC by increasing miR-92b-3p expression and decreasing KLF4 expression in the aorta. In conclusion, our study suggests that CUR attenuates vascular calcification via the exosomal miR-92b-3p/KLF4 axis.

Exosomal miR-17-5p from adipose-derived mesenchymal stem cells inhibits abdominal aortic aneurysm by suppressing TXNIP-NLRP3 inflammasome

Background

Preclinical studies have suggested that adipose-derived mesenchymal stem cells (ADSCs) transplantation can suppress abdominal aortic inflammation and aneurysm expansion through paracrine factors. Yet, the mechanism of action is not fully understood. In the present study, we further examined the function and mechanism of ADSC-derived exosomes (ADSC-exos) and their microRNA-17-5p (miR-17-5p) on the abdominal aortic aneurysm (AAA) progression.

Methods

ADSC-exos were isolated and identified. DiR and PKH67 staining were used to trace ADSC-exo in vivo and in vitro. Raw264.7 cells were applied to perform in vitro experiments, while a murine AAA model induced using angiotensin II (Ang II) was used for in vivo testing. The expression level of miR-17-5p in macrophages and Ang II-treated macrophages after ADSC-exos treatment was determined using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The target relation between miR-17-5p and thioredoxin-interacting protein (TXNIP) was identified by a dual-luciferase reporter gene assay. Artificial activation and block of experiments of miR-17-5p and TXNIP were conducted to clarify their functions in inflammation during AAA progression. The severity of AAA between groups was assessed by maximal aorta diameter, AAA incidence, survival rate, and histological stainings. Besides, inflammasome-related proteins and macrophage pyroptosis were further evaluated using western blot, RT-qPCR, and enzyme-linked immunosorbent assay (ELISA).

Results

The ADSC-exos were isolated and identified. In vivo testing showed that ADSC-exos were mainly distributed in the liver. Meanwhile, in vitro experiments suggested that ADSC-derived exosomes were taken up by macrophages, while inside, ADSC-exos miR-17-5p decreased a TXNIP induced by Ang II by directly binding to its 3′-untranslated region (3’UTR). Furthermore, overexpression of miR-17-5p enhanced the therapeutic function of ADSC-exos on inflammation during AAA expansion in vivo, while its inhibition reversed this process. Finally, overexpressed TXNIP triggered macrophage pyroptosis and was alleviated by ADSC-derived exosomes in vitro.

Conclusion

ADSC-exos miR-17-5p regulated AAA progression and inflammation via the TXNIP-NLRP3 signaling pathway, thus providing a novel insight in AAA treatment.

The crosstalk between endothelial cells and vascular smooth muscle cells aggravates high phosphorus-induced arterial calcification

Arterial calcification is highly prevalent, particularly in patients with end-stage renal disease (ESRD). The osteogenic differentiation of vascular smooth muscle cells (VSMCs) is the critical process for the development of arterial calcification. However, the detailed mechanism of VSMCs calcification remains to be elucidated. Here, we investigated the role of exosomes (Exos) derived from endothelial cells (ECs) in arterial calcification and its potential mechanisms in ESRD. Accelerated VSMCs calcification was observed when VSMCs were exposed to ECs culture media stimulated by uremic serum or high concentration of inorganic phosphate (3.5 mM Pi). and the pro-calcification effect of the ECs culture media was attenuated by exosome depletion. Exosomes derived from high concentrations of inorganic phosphate-induced ECs (ECs^HPi-Exos) could be uptaken by VSMCs and promoted VSMCs calcification. Microarray analysis showed that miR-670-3p was dramatically increased in ECs^HPi-Exos compared with exosomes derived from normal concentrations of inorganic phosphate (0.9 mM Pi) induced ECs (ECs^NPi-Exos). Mechanistically, insulin-like growth factor 1 (IGF-1) was identified as the downstream target of miR-670-3p in regulating VSMCs calcification. Notably, ECs-specific knock-in of miR-670-3p of the 5/6 nephrectomy with a high-phosphate diet (miR-670-3p^EC-KI + NTP) mice that upregulated the level of miR-670-3p in artery tissues and significantly increased artery calcification. Finally, we validated that the level of circulation of plasma exosomal miR-670-3p was much higher in patients with ESRD compared with healthy controls. Elevated levels of plasma exosomal miR-670-3p were associated with a decline in IGF-1 and more severe artery calcification in patients with ESRD. Collectively, these findings suggested that ECs-derived exosomal miR-670-3p could promote arterial calcification by targeting IGF-1, which may serve as a potential therapeutic target for arterial calcification in ESRD patients.

Protective role of small extracellular vesicles derived from HUVECs treated with AGEs in diabetic vascular calcification

The pathogenesis of vascular calcification in diabetic patients remains elusive. As an effective information transmitter, small extracellular vesicles (sEVs) carry abundant microRNAs (miRNAs) that regulate the physiological and pathological states of recipient cells. In the present study, significant up-regulation of miR-126-5p was observed in sEVs isolated from human umbilical vein endothelial cells (HUVECs) stimulated with advanced glycation end-products (A-EC/sEVs). Intriguingly, these sEVs suppressed the osteogenic differentiation of vascular smooth muscle cells (VSMCs) by targeting BMPR1B, which encodes the receptor for BMP, thereby blocking the smad1/5/9 signalling pathway. In addition, knocking down miR-126-5p in HUVECs significantly diminished the anti-calcification effect of A-EC/sEVs in a mouse model of type 2 diabetes. Overall, miR-126-5p is highly enriched in sEVs derived from AGEs stimulated HUVECs and can target BMPR1B to negatively regulate the trans-differentiation of VSMCs both in vitro and in vivo.

Inhibiting uptake of extracellular vesicles derived from senescent bone marrow mesenchymal stem cells by muscle satellite cells attenuates sarcopenia

Objective

Osteoporosis is associated with senescence of bone marrow mesenchymal stem cells (BMSCs). Extracellular vesicles derived from senescent BMSCs (BMSC-EVs) could be uptaken by muscle satellite cells (SCs). We hypothesized that inhibiting the uptake of harmful BMSC-EVs by SCs could prevent patients with osteoporosis complicated with sarcopenia.

Methods

Bioinformatics analysis was used to analyze senescent SCs. Myogenic potential of SCs was measured using myogenesis assay and immunofluorescence while muscle atrophy was measured using histological evaluation. And the interaction of cluster of differentiation (CD) 81 and the membrane proteins of SCs was verified using biotin pulldown assay.. CD81-specific siRNA (si-CD81) was used to knockdown CD81 and anti-CD81 antibody (anti-CD81 Ab) was used to block CD81.

Results

Differentially expressed genes in senescent SCs were enriched in muscle cell differentiation. The myogenic potential of senescent SCs was significantly decreased. Senescent BMSC-EVs impaired myogenesis of SCs. CD81 on the surface of BMSC-EVs could bind to membrane proteins of SCs. Both knockdown of CD81 and blocking CD81 prevented the uptake of senescent BMSC-EVs by SCs, thus relieving harmful effects of senescent BMSC-EVs on muscle atrophy.

Conclusion

Blocking CD81 on the surface of senescent BMSC-EVs attenuates sarcopenia in aged mice, which could be useful for prevention of sarcopenia in patients with osteoporosis in clinical practice.

Translational potential of this article

Inhibiting uptake of extracellular vesicles derived from senescent bone marrow mesenchymal stem cells by muscle satellite cells can prevent muscle atrophy in aged mice and has potential for application in treating sarcopenia.

Melatonin as an Anti-Aging Therapy for Age-Related Cardiovascular and Neurodegenerative Diseases

The concept of “aging” is defined as the set of gradual and progressive changes in an organism that leads to an increased risk of weakness, disease, and death. This process may occur at the cellular and organ level, as well as in the entire organism of any living being. During aging, there is a decrease in biological functions and in the ability to adapt to metabolic stress. General effects of aging include mitochondrial, cellular, and organic dysfunction, immune impairment or inflammaging, oxidative stress, cognitive and cardiovascular alterations, among others. Therefore, one of the main harmful consequences of aging is the development and progression of multiple diseases related to these processes, especially at the cardiovascular and central nervous system levels. Both cardiovascular and neurodegenerative pathologies are highly disabling and, in many cases, lethal. In this context, melatonin, an endogenous compound naturally synthesized not only by the pineal gland but also by many cell types, may have a key role in the modulation of multiple mechanisms associated with aging. Additionally, this indoleamine is also a therapeutic agent, which may be administered exogenously with a high degree of safety. For this reason, melatonin could become an attractive and low-cost alternative for slowing the processes of aging and its associated diseases, including cardiovascular and neurodegenerative disorders.

Stem Cell-derived Exosomal MicroRNA as Therapy for Vascular Age-related Diseases

Vascular age-related diseases describe a group of age-related chronic diseases that result in a considerable healthcare burden to society. Vascular aging includes structural changes and dysfunctions of endothelial cells (ECs) and smooth muscle cells (SMCs) in blood vessels. Compared with conventional treatment for vascular age-related diseases, stem cell (SC) therapy elicits better anti-aging effects viathe inhibition/delay ECs and SMCs from entering senescence. Exosomal noncoding RNA (ncRNAs) in vascular aging and stem cell-derived exosomal microRNAs (SCEV-miRNAs), especially in mesenchymal stem cells, have an important role in the development of age-related diseases. This review summarizes SCEV-miRNAs of diverse origins that may play a vital role in treating subclinical and clinical stages of vascular age-related disorders. We further explored possible age-related pathways and molecular targets of SCEV-miRNA, which are associated with dysfunctions of ECs and SMCs in the senescent stage. Moreover, the perspectives and difficulties of SCEV-miRNA clinical translation are discussed. This review aims to provide greater understanding of the biology of vascular aging and to identify critical therapeutic targets for SCEV-miRNAs. Though still in its infancy, the potential value of SCEV-miRNAs for vascular age-related diseases is clear.

Cellular Crosstalk in the Vascular Wall Microenvironment: The Role of Exosomes in Vascular Calcification

Vascular calcification is prevalent in aging, diabetes, chronic kidney disease, cardiovascular disease, and certain genetic disorders. However, the pathogenesis of vascular calcification is not well-understood. It has been progressively recognized that vascular calcification depends on the bidirectional interactions between vascular cells and their microenvironment. Exosomes are an essential bridge to mediate crosstalk between cells and organisms, and thus they have attracted increased research attention in recent years. Accumulating evidence has indicated that exosomes play an important role in cardiovascular disease, especially in vascular calcification. In this review, we introduce vascular biology and focus on the crosstalk between the different vessel layers and how their interplay controls the process of vascular calcification.

Extracellular vesicles enclosed-miR-421 suppresses air pollution (PM2.5 )-induced cardiac dysfunction via ACE2 signalling

Air pollution, via ambient PM_2.5, is a big threat to public health since it associates with increased hospitalisation, incidence rate and  mortality of cardiopulmonary injury. However, the potential mediators of pulmonary injury in PM_2.5‐induced cardiovascular disorder are not fully understood. To investigate a potential cross talk between lung and heart upon PM_2.5 exposure, intratracheal instillation in vivo, organ culture ex vivo and human bronchial epithelial cells (Beas‐2B) culture in vitro experiments were performed respectively. The exposed supernatants of Beas‐2B were collected to treat primary neonatal rat cardiomyocytes (NRCMs). Upon intratracheal instillation, subacute PM_2.5 exposure caused cardiac dysfunction, which was time‐dependent secondary to lung injury in mice, thereby demonstrating a cross‐talk between lungs and heart potentially mediated via small extracellular vesicles (sEV). We isolated sEV from PM_2.5‐exposed mice serum and Beas‐2B supernatants to analyse the change of sEV subpopulations in response to PM_2.5. Single particle interferometric reflectance imaging sensing analysis (SP‐IRIS) demonstrated that PM_2.5 increased CD63/CD81/CD9 positive particles. Our results indicated that respiratory system‐derived sEV containing miR‐421 contributed to cardiac dysfunction post‐PM_2.5 exposure. Inhibition of miR‐421 by AAV9‐miR421‐sponge could significantly reverse PM_2.5‐induced cardiac dysfunction in mice. We identified that cardiac angiotensin converting enzyme 2 (ACE2) was a downstream target of sEV‐miR421, and induced myocardial cell apoptosis and cardiac dysfunction. In addition, we observed that GW4869 (an inhibitor of sEV release) or diminazene aceturate (DIZE, an activator of ACE2) treatment could attenuate PM_2.5‐induced cardiac dysfunction in vivo. Taken together, our results suggest that PM_2.5 exposure promotes sEV‐linked miR421 release after lung injury and hereby contributes to PM_2.5‐induced cardiac dysfunction via suppressing ACE2.

Evaluating the Role of lncRNAs in the Incidence of Cardiovascular Diseases in Androgenetic Alopecia Patients

Hair loss occurs in patients with Androgenetic Alopecia (AGA). The pattern of hair loss is different between men and women. The main cause of hair loss is increased cell apoptosis and decreased regeneration, proliferation and differentiation processes in hair follicles. Long Non-Coding RNAs (lncRNAs) are one of the most important molecules that regulate the processes of apoptosis, regeneration, proliferation and differentiation in hair follicles. Since studies have shown that lncRNAs can be effective in the development of cardiotoxicity and induction of cardiovascular disease (CVD); so effective lncRNAs in the regulation of regeneration, proliferation, differentiation and apoptosis of hair follicles can be involved in the development of CVD in AGA patients with. Therefore, this study investigated the lncRNAs involved in increasing apoptosis and reducing the processes of regeneration, proliferation and differentiation of hair follicles. The aim of the current study was to evaluate the role of lncRNAs as a risk factor in the incidence of CVD in AGA patients; it will help to design treatment strategies by targeting signaling pathways without any cardiotoxicity complications.

Insights Into the Role of Mitochondria in Vascular Calcification

Vascular calcification (VC) is a growing burden in aging societies worldwide, and with a significant increase in all-cause mortality and atherosclerotic plaque rupture, it is frequently found in patients with aging, diabetes, atherosclerosis, or chronic kidney disease. However, the mechanism of VC is still not yet fully understood, and there are still no effective therapies for VC. Regarding energy metabolism factories, mitochondria play a crucial role in maintaining vascular physiology. Discoveries in past decades signifying the role of mitochondrial homeostasis in normal physiology and pathological conditions led to tremendous advances in the field of VC. Therapies targeting basic mitochondrial processes, such as energy metabolism, damage in mitochondrial DNA, or free-radical generation, hold great promise. The remarkably unexplored field of the mitochondrial process has the potential to shed light on several VC-related diseases. This review focuses on current knowledge of mitochondrial dysfunction, dynamics anomalies, oxidative stress, and how it may relate to VC onset and progression and discusses the main challenges and prerequisites for their therapeutic applications.